RadChem 2026

May 10, 2026, 3:00 PM → May 15, 2026, 10:00 PM Europe/Prague

Casino Conference Centre

Mojmír Němec (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry), Vaclava Havlova (UJV Rez, a.s.), Jan Kučera (Nuclear Physics Institute of the Czech Academy of Sciences), Radiochemical Conference

The 20^th Radiochemical Conference - RadChem 2026 - aims at maintaining the 65 years long tradition of this conference series. We strive to continue organising a fruitful and well attended platform for contacts between experts working in both basic and applied research in all aspects of nuclear- and radiochemistry.

The conference is organised on behalf of the Division of Nuclear and Radiochemistry of the European Chemical Society (EuChemS) as a part of the series of general European radiochemical conferences organized every other year. The conference is organised in co-operation with the International Atomic Energy Agency and support by IUPAC is under negotiation.

More details can be found at the conference web at http://www.radchem.cz. 

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Detailed conference programme

Programme_260505.pdf

RadChem_2026_Booklet_of_Abstracts_-_Errata_2026-05-08.pdf

Radiochemistry in Spain (donated by Catalina Gasco) Historia Radioquímica_CGasco_uv_26.pdf Libro_completo_Radioquimica_inglés_CGL en-GB.pdf

Sun, May 10

3:00 PM → 6:00 PM Registration

6:00 PM → 6:30 PM Socials: RadChem 2026 Opening

6:30 PM → 7:30 PM Plenary: Hevesy Medal Award Ceremony

Conveners: Zsolt Révay (Technische Universität München - FRM II), Mojmír Němec (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry)

6:45 PM A life of a physicist in the radiochemical laboratory

As it happens that way, that I am a this year Hevesy Medal awarded I would like to tell some words on my experience. I am a physicist, who was graduated in neutrino physics in 1984, but the life paths throwed me into environmental radioactivity and radiochemistry. I deserve my scientific career to Chernobyl accident. I started work for the Institute of Nuclear Physics from gamma spectrometry in 1986 but very soon, in beginning of 1991 I became a fellow of IAEA Laboratories Seibersdorf where I received a four months training in radiochemistry from Dr. Jerome La Rosa. It was about Pu and Am. I met there Dr. Nora Vajda, and they both remained my radiochemical gurus for rest of my life. From the discussion with them I took the idea of sequential radiochemical procedure which result in a multi-elemental analyses and thus a much complete characterization of sample. I am keeping faithful to this idea. After returning I introduced Pu and Am analyses to my home lab. In that time my first interest was in forest environment: mushrooms, plants and litter. In 1998 with help of Dr. Nora Vajda I started use of crown ether for Sr-90 analyses. So, from that time my procedure included gamma spectrometry, Pu, Am and Sr-90. Next more than ten years I was dealing mostly with biota samples searching for bio-accumulations. The animal bones were main kind of samples. They were coming from herbivorous mammals, birds of prey, foxes, small insectivorous and rodents from Poland. Also in 1998 I started a collaboration with prof. Maria Agata Olech on radionuclides in Antarctic and Arctic environment, so samples of animal tissues of different species (found died in polar regions) like for example various species of penguins were also analyzed. In a collaboration with biologists I did also studies on invertebrates coming from Poland and Chernobyl Zone. Finally, the human bones received from join replacement surgery were also analyzed. The applied analytical techniques besides gamma and alpha spectrometry included also LSC, mainly used for Sr-90 but with time the sequential procedure was (not always) was enlarged by analyses for Tc-99, Ni-63 and Pu-241 . From 2007 also mass spectrometry was included to get Pu-240/Pu-239 and sometimes for Np-237. From the very beginning I was involved in study of the radioactivity in the air. With my two PhD students and few more under graduated students I did a long term studies of Pu and Am in aerosols and air precipitation. The majority of 12 completed PhD works, which I supervised (and 3 ongoing now) were based on radiochemistry. During my talk I will present some of the most interesting cases from my experience as well as I will tell on my current works.

Speaker: Jerzy-Wojciech Mietelski (The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN))

7:30 PM → 9:30 PM Socials: Welcome Reception

Mon, May 11

8:00 AM → 12:00 PM Registration

8:20 AM → 8:30 AM Socials: DNRC Medal Award

Conveners: Marko Štrok (Jožef Stefan Institute), Mojmír Němec (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry)

8:30 AM → 10:00 AM Plenary: PLN 1

Conveners: Mojmír Němec (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry), Marko Štrok (Jožef Stefan Institute)

8:30 AM Positioning Sg, Bh. Hs and Cn into the Periodic Table – a historic review

The development of fast on-line chemistry techniques – coupled to on-line detection systems - allowed to push the limit of chemical knowledge into the range of the Perioidc Table where isotopes of elements have half-lives in the second range only. With the On-Line Gas chemistry Apparatus OLGA (using isothermal gas chromatography) the chemical identification of Seaborgium, Sg [1] and Bohrium, Bh [2] became possible in form of their oxochlorides and with the In-situ Volatilisation and On-line detection system IVO (using themochromatography) the elements Hassium, Hs [3] (in form of its tetroxyde molecule) as well as Copernicium, Cn [4] (in its elemental state) where studied. These first ever chemical studies of elements at the upper end of the Periodic Table paved the way for a new generation of chemical investigations of heaviest elements. Only recently separation times significantly below one second were achieved [5] which enables future studies of even heavier elements.
[1] M. Schädel et al, Nature, 388, 55 (1997)
[2] R. Eichler et al., Nature, 407, 63 (2000)
[3] Ch. E. Düllmann et al., Nature 418, 859 (2002)
[4] R. Eichler et al., Nature 447, 72 (2007)
[5] G. Tiebel et al. J. Phys. Chem. C, in print (2026)

Speaker: Prof. Heinz Gäggeler (Paul Scherrer Institut)

9:00 AM Applications of cutting-edge mass spectrometry in multidisciplinary environmental studies

Efficient and accurate analysis of radionuclides is critically important across a wide range of fields, including environmental and food radioactivity monitoring, decommissioning of nuclear facilities and waste management, nuclear forensics, geochronology, earth science and environmental tracer studies. While most γ-emitting radionuclides can be measured directly after simple sample preparation, the determination of difficult-to-measure (DTM) radionuclides, such as α- and β- emitters, or γ-emitters at very low-concentrations, has long been a challenge in radiochemical analysis.
In recent decades, advances in mass spectrometry, particularly Inductively Coupled Plasmas Mass Spectrometry (ICP-MS) and Accelerator Mass Spectrometry (AMS), have contributed greatly to rapid, efficient, and simultaneous multi-isotope measurement of DTM radionuclides for a wide variety of sample types. These novel mass spectrometric techniques also allow for the determination of radionuclides at trace and ultra‑trace levels that are inaccessible to traditional radiometric methods, thereby opening new opportunities in environmental tracer applications.
This paper introduces recent research progress from Radioecology and Tracer Studies (RTS) group at DTU Sustain, Denmark. Through selected case studies, we highlight the powerful role of modern mass spectrometry in advancing multidisciplinary environmental research.

Speaker: Prof. Jixin Qiao (Technical University of Denmark)

9:30 AM Radiochemical Separation for the Recovery of 244Pu from Legacy Mark 18A Targets

The recovery of long lived transneptunium isotopes from legacy reactor irradiated materials represents a critical intersection of radiochemistry, national resource stewardship, and nuclear talent development. The Mark 18A targets, produced and irradiated at the Savannah River Site during the 1960s through the 1980s, contained kilogram quantities of ${}^{242}\mathrm{Pu}$ that were exposed to sustained high neutron flux conditions to generate isotopes including ${}^{244}\mathrm{Pu}$, ${}^{246}\mathrm{Cm}$ to ${}^{248}\mathrm{Cm}$, and Am isotopes. Of the eighty six irradiated targets, twenty one were historically processed, providing the principal global supply of high purity ${}^{244}\mathrm{Pu}$ after electromagnetic enrichment at Oak Ridge National Laboratory. The remaining sixty five targets represent the largest existing inventory of unseparated ${}^{244}\mathrm{Pu}$ and heavy curium isotopes and are currently maintained by the US Department of Energy (US-DOE).
The Mark 18A Target Material Recovery Program, established by the US DOE, was initiated to recover these strategically important isotopes to support nuclear forensic science, heavy element production, and national research priorities. The recovery effort requires the integration of advanced radiochemical separations designed to isolate plutonium fractions enriched in ${}^{244}\mathrm{Pu}$ while simultaneously managing complex mixtures of actinides, fission products, and target matrix materials. The work involves dissolution chemistry, oxidation state control, selective precipitation, solvent extraction, ion exchange, and purification methodologies developed to achieve isotopic and chemical purity requirements. Processing activities leverage infrastructure and expertise at the Savannah River National Laboratory for target dissolution and initial separations, followed by material stabilization and long term storage capabilities at Oak Ridge National Laboratory.
Beyond isotope recovery, the program provides a unique platform for the advancement of applied radiochemistry. The processing of high activity legacy materials requires refinement of actinide speciation knowledge, development of separation flowsheets, and demonstration of process scale radiochemical operations. These activities provide an important framework for training the next generation of radiochemists through university participation. Students engage in research addressing actinide separation science, analytical characterization, and process modeling, while gaining experience in handling complex nuclear materials and understanding the integration of radiochemistry with national mission objectives.
The recovery of ${}^{244}\mathrm{Pu}$ from Mark 18A targets demonstrates the continued relevance of radiochemical science in addressing contemporary nuclear challenges. The project illustrates how legacy nuclear materials can be transformed into critical national resources while simultaneously supporting education, workforce development, and technological innovation in actinide chemistry.

Speaker: Kenneth Czerwinski (University of Nevada, Las Vegas)

10:00 AM → 10:30 AM Coffee Break

10:30 AM → 12:00 PM Plenary: PLN 2

Conveners: Václava Havlová (International Atomic Energy Agency), Heinz Gaeggeler (Paul Scherrer Institut)

10:30 AM The role of actinide separation chemistry in sustainable nuclear fuel cycles

Nuclear energy is a secure, low carbon source of energy. After irradiation in the reactor, most countries store the used (or spent) nuclear fuels ready for geological disposal (the 'open' or 'once through' fuel cycle). However, the overall sustainability of nuclear energy can be enhanced by moving towards 'closed' fuel cycles based on the recycling of various components of used fuels. A key step in enabling fuel cycles is nuclear fuel reprocessing where the actinides (and potentially other elements) are chemically separated and purified ready for recycling. Using the concepts of sustainability as the background, this paper provides an overview of the benefits and challenges of used fuel reprocessing. It then describes some developments from European and UK R&D programmes over the last two decades, focused on advanced separation processes for uranium, plutonium and minor actinides.

Speaker: Robin Taylor (The University of Manchester)

11:00 AM A Single-Center Heidelberg Experience: Molecular Biomarkers Beyond PSA for Risk Stratification in Combined Targeted Radioligand Therapy

Targeted radioligand therapy (TRT) directed against prostate-specific membrane antigen (PSMA) represents a promising strategy for metastatic castration-resistant prostate cancer (mCRPC). However, reliable treatment prediction and therapeutic resistance limits durable clinical benefit.
We describe a prospective single-center experience from Heidelberg encompassing ~100 mCRPC patients treated with tandem β⁻-emitting [177Lu]Lu-PSMA-617 (3.7–7.4 GBq per cycle) and α-emitting [225Ac]Ac-PSMA-617 (4–8 MBq per cycle) within a multimodal theranostic framework. This project integrates cocktail radionuclide treatment, PSMA-based molecular imaging employing either [18F]PSMA-1007, [68Ga]Ga-PSMA-11, or [99mTc]Tc-GCK-01, circulating tumor DNA (ctDNA) profiling, and circulating tumor cell (CTC) phenotyping to characterize molecular determinants of response and resistance.
The cocktail strategy was applied to exploit complementary radiobiological properties: β⁻-particles provide cross-fire effects suitable for heterogeneous and bulky lesions, whereas α-particles deliver high and short-range cytotoxicity targeting micrometastatic or radioresistant tumor compartments, thereby aiming to overcome emerging resistance under β⁻-monotherapy.
Across 172 longitudinal plasma samples, ctDNA analysis showed that tumor fraction (TFx) closely paralleled prostate-specific antigen (PSA) kinetics during early treatment. Baseline TFx distinguished metastatic stages (p=0.027) and, as a time-dependent variable, was associated with a five-fold increased risk of progression (HR 4.9, 95% CI 1.2–20.1, p=0.026). Stratification by copy-number alteration (CNA) burden defined biologically distinct subgroups, with high CNA burden strongly correlating with elevated TFx (p=8.09×10⁻8), aggressive disease, and shorter median overall survival (8.3 vs. 13.8 months). Recurrent events included amplifications at 1q32.1, 8q21.3, 10q22.3, and 12q24.22, and deletions in PTEN, RB1, BRCA2, and ATM, affecting TP53 signaling and homologous recombination repair. Longitudinal profiling showed clonal expansion of 8q21.3 and 10q21.2 at progression, and in representative cases, rising TFx and CNA burden preceded radiographic progression, supporting ctDNA as an early resistance marker.
In a CTC subcohort, ~400 CTCs were isolated across serial samples (median 8 cells/sample) and profiled for epithelial cell adhesion molecule (EpCAM) and PSMA. Non-responders had significantly higher EpCAM and lower PSMA levels at baseline and after the first cycle (p<0.001). During subsequent cycles, both markers declined in non-responders, whereas responders maintained EpCAM but progressively lost PSMA, consistent with therapy-induced antigen modulation. Transcriptome analysis of CTCs revealed upregulation of genes involved in DNA-damage repair, anti-apoptotic signaling, proliferation, and membrane trafficking, likely driving dynamic EpCAM–PSMA changes and contributing to resistance under tandem β⁻-/α-based TRT.
This multidimensional Heidelberg cohort demonstrates the feasibility and clinical relevance of integrating tandem radionuclide cocktail therapy, molecular imaging, and serial liquid biopsy within a unified theranostic framework. The approach provides mechanistic insight into resistance evolution, enables molecular risk stratification, and, with prospective validation, may support individualized treatment optimization in advanced mCRPC.

Speaker: Martina Benešová-Schäfer

11:30 AM Corrosion of nuclear waste glasses in long term tests

Alkali borosilicate glasses were internationally selected as basic immobilizing matrices for high level nuclear waste aiming to retain toxic components for timeframes exceeding millennia. Corrosion of glasses is a complex process evolving with time which is mainly dependent on glass composition and environmental conditions. Laboratory tests of nuclear waste forms are mandatory as a part of qualification procedures in nuclear waste management with a number of standard test protocols developed which are used to assess the durability of vitrified radioactive waste based on understanding of glass dissolution mechanisms [1]. However, laboratory experiments are oversimplified and cannot account of all factors of the disposal environment which are complex and changing with time such as the variable saturation conditions, intrinsic effects of radiation, and biochemical activities which occur in addition to geochemical and climatic changes. Field tests aim to verify the representativeness of laboratory results to those observed under disposal conditions, especially assessing the rate of radionuclide releases which serve as a source term in performance analysis of disposal sites and hence to validate modelling approaches. Data on long-term behaviour and corrosion of archaeological and natural analogue glasses are most useful especially those from available ancient natural glasses containing radioactive uranium and thorium and their decay products [2]. Field tests typically include sampling of waters and hosting materials in contact with wasteforms as well as analysis of dynamic of species including radionuclides release and assessment of retention capacity of materials. It is notable that in many cases the combined effect of real environment and radiation was found substantially changing the behaviour of nuclear waste forms compared standard testing arrangements. Testing for extended timescales lasting years and decades are highly desirable to further define the alternating release rates of radionuclides from nuclear waste gasses and transition of glass corrosion to residual rate of a reaction under conditions close to repository sites. Silicate glasses corrode in water via two main processes—(i) diffusion-controlled ion exchange and (ii) hydrolysis. During the long-term tests the mechanisms of glass corrosion may change. In dilute near-neutral solutions, the ion exchange controls the initial release of cations and can dominate over hydrolysis at relatively low temperatures and not high pH for many hundreds and thousands of years. We analyse the alterations of glass corrosion mechanism during the long-term tests revealing dominant contributions at each phase of nuclear waste glass corrosion process as well as the effect of intrinsic radiations caused by the natural decay of waste radionuclides. We reveal that depending on environmental conditions either diffusion-controlled ion exchange or hydrolysis of glass network control the release of radionuclides into the contacting groundwater.
1. Thorpe, C.L. et al. Forty years of durability assessment of nuclear waste glass by standard methods. npj Materials Degradation, 2021, 5: 61.
2. Poluektov, V.V. et al. Uranium Retention in Silica-Rich Natural Glasses: Nuclear Waste Disposal Aspect. Ceramics 2023, 6, 1152-1163.

Speaker: Dr Michael Ojovan (Wuhan University of Technology)

12:00 PM → 1:30 PM Lunch

1:30 PM → 3:00 PM Actinoids and Transactinoids: TAN 1

Conveners: Andreas Türler, Václav Tyrpekl (Faculty of Science, Charles University)

1:30 PM On the volatility and stability of the Sg(CO)6 complex

Chemical properties of the superheavy elements (SHE) are unique due to the strong relativistic effects, which influence their properties, e.g., the stability of the metal-ligand bonding in carbonyl complexes. The formation of the carbonyl complex of Sg (Z = 106) and its interaction with a silicon oxide surface was reported more than 10 years ago [1]. This complex is still so far the only SHE compound featuring a metal-carbon bond as is typical for organometallic compounds. Further developments to study this compound class have been performed by several research groups to prepare new experiments, aiming at the synthesis of a carbonyl complex with Bh (Z = 107) and at measurements of the stability of Sg(CO)6, which would give a completely new access to the chemistry of the atom-at-a-time heaviest elements [2]. Recently, a new study, of 259Sg(CO)6, has been performed at the TASCA separator at GSI Darmstadt, Germany, exploiting the cold-fusion nuclear reaction 52Cr(208Pb,1n)259Sg. An advanced detection setup consisting of two types of detector arrays for the detection of non-volatile and volatile products was applied in this study, which provides new information on the stability of Sg(CO)6 complex.
1. Even, J. et al. Science 345, 1491–1493 (2014).
2. Eichler, R. et al. EPJ Web of Conferences 131, 07005 (2016)

Speaker: Alexander Yakushev (GSI Helmholtzzentrum für Schwerionenforschung GmbH)

2:00 PM Towards livermorium chemistry: Atom-at-a-time gas chromatography studies with polonium

The chemistry of the radioelement polonium has gained growing interest due to its formation in accelerator-driven systems, but it is scarcely studied owing to its pronounced radiotoxicity. As the lighter homologue of the superheavy element livermorium, whose chemical behaviour is unknown experimentally, investigations of polonium are also needed to prepare future experimental studies of livermorium. Thus, we have investigated the volatility of atom-at-a-time quantities of polonium by applying gas-solid thermochromatography. $^{204}$Po was produced by irradiating $^{206}$Pb targets with a $^{3}$He beam. Experiments were performed in helium gas on quartz surfaces with different degrees of hydroxylation. On quartz glass with low OH-concentrations, a volatile species with an adsorption enthalpy of 85$_{-2}^{+3}$ kJ/mol was found and assigned to elemental polonium. On a more highly hydroxylated quartz glass, an additional deposition zone of a less volatile species was observed and attributed to a polonium species formed by chemical reaction with the surface. In oxygen atmosphere on less hydroxylated quartz glass, elemental polonium and two additional, less volatile, probably oxidized species were observed. The experiments indicate that chemical reactions of the analysed species with the solid phase are just as important to consider as gas phase reactions. The influence of the structure and reactivity of the surface therefore has to be carefully analysed in future gas chromatography experiments.

Speaker: Katharina Hermainski (Johannes Gutenberg University Mainz / GSI Helmholtzzentrum Darmstadt)

2:20 PM Study of the Possibility of Applying Electrochemical Processes to Change the Oxidation State of Radiothallium Trace Amounts

The paper deals with the possibility of using chronoamperometry and cyclic voltammetry to adjust the oxidation state of trace amounts of radiothallium in a flow-through electrochemical cell. It is expected that the obtained results will be applicable for future studies, since thallium is a group 13 homologue of the superheavy element nihonium (Z = 113), according to the periodic table.

The electrochemical apparatus is based on a Gamry Reference 600 potentiostat connected to a three-electrode set-up (glassy carbon working electrode, counter graphite electrode and reference Ag|AgCl|3M KCl electrode). This set-up should allow changing the oxidation state of trace amounts of an analyte in a flow-through regime. It can be used not only for the analysis of physicochemical properties, but also as a preliminary step to subsequent selective extraction of a particular electrochemically transformed specie and gamma spectroscopic analysis.

During the experiments, a redox pair Tl+I / Tl+III at E ≈ 1.25 V. Experiments were carried out with both medical 201Tl (T1/2 = 3.04 d) and a mixture of cyclotron-produced thallium radioisotopes produced by bombardment of a gold target with 3He ion beam with energy of 48 MeV. Differentiation between thallium oxidation states is performed by liquid-liquid extraction using Aliquat 336 extraction reagent or, alternatively, ion exchanger columns at the outlet of the electrochemical apparatus.

This work presents the results of electrochemical experiments in a 0.2M HCl environment where thallium ions are oxidatively converted from monovalent to trivalent with sufficient efficiency for further use.

Speaker: Jakub Sochor (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry)

2:40 PM Comparative Study of Mo and W Tracer Scale Extraction from Nitric or Perchloric Acid to Diisooctylphosphinic Acid

Liquid-phase chemistry of heavier group 6 elements is yet to be completely understood, especially when it comes to their tracer-scale chemistry and seaborgium homology. At such concentrations, Mo and W form only monomeric species, whereas the exact form of those species has not yet been fully agreed upon. Nonetheless, some theoretical and experimental work dealing with the liquid-phase chemistry of group 6 elements has been carried out; a few articles deal with their ability to hydrolyse, but most focus on halide speciation and behaviour.
In this work, we are neither trying to resolve the exact aqueous-phase speciation of group 6 elements, nor their ability to hydrolyse. In the selected approach, we study extraction properties of said elements with typical molybdenum extraction agent, diisooctyphosphinic acid (or Cyanex 272), and we follow the trends across the group with the prospect of designing an experiment that would possibly unravel a new piece of information about seaborgium chemistry.
Thus far, two acidity regions with two completely different mechanisms of extraction have been identified – a region independent of the selected acids, where it is suspected that a chelate is formed, and a region dependent on the selected acids, specifically on the concentration of their anion, where the formation of ionic associates is assumed. From the seaborgium standpoint, however, both regions are significant and complement each other given the information they provide. It seems that the willingness to chelate strongly decreases with increasing Z in the group, while the willingness to form ionic associates evinces quite the opposite trend. While some supporting experiments, characterisations, and data interpretations are still to be carried out, the system in question seems very promising for a future seaborgium extraction experiment.

Speaker: Dr Pavel Bartl (Czech Technical University in Prague)

1:30 PM → 3:00 PM Nuclear Fuel Cycle: NFC 1

Conveners: Marco Cologna (EC-JRC), Václava Havlová (International Atomic Energy Agency)

1:30 PM Recyclability of advanced nuclear fuels: Dissolution experiments on irradiated (U,Pu,Am)O2 and (U,Am)O2 fuels

Several pioneering irradiation experiments on minor actinide bearing blanket materials have been performed at High Flux Reactor of NRG PALLAS. One aim of these projects has been to assess solutions for reducing the volume and hazard of high level long-lived radioactive waste, including closure of the nuclear fuel cycle. First-of-a-kind post-irradiation examination (PIE) data have been obtained for americium containing sphere-pac fuels [1] and minor actinide bearing blanket materials [2].
Within the European FREDMANS project the recyclability of these fuels is being studied to complete the nuclear fuels cycle for these fuels. The recyclability part addresses the fact that oxide fuels for Gen IV systems and IMF may contain high concentrations (up to 50 %) of plutonium and minor actinides. High concentrations of plutonium in oxide fuels could strongly limit the solubility in nitric acid. However, the effect of the MA-content (specifically Am) on the dissolution capability is still unknown. Yet this effect forms a crucial aspect in the design of a reprocessing flow-sheet for oxide fuels for Gen IV systems, as well as for IMF. The research studies both fresh fuel [3] and irradiated fuels.
Two types of irradiated fuels are examined, first one mixed uranium/plutonium oxide fuel with (small) amounts of americium representing the minor actinide fraction; available in two forms: Pellets and Sphere-Pac. The research question of interest is therefore to not only determine the overall dissolution kinetics of this type of fuel but also to compare, if possible, the two physical fuel forms in terms of dissolution kinetics. The second fuel consists of (U,Am)O2 with a relatively high americium content of ca. 13%.
The experiments are performed in the chemical hot cell of the Hot cells laboratories, this hot cell is equipped with a leak tight inbox allowing to work with alpha emitting nuclides and concentrated acids. The experiments follow the PUREX process dissolution steps; i.e. dissolution in hot nitric acid. A slice of the fuel is cut during the PIE, including the cladding. The fuel amounts typically 300-500 mg. The dissolution experiments takes 360 minutes, during the experiment aliquots are taken for subsequent analyses (gamma spectrometry, TIMS) to provide information on the dissolution kinetics.
References:
1. A. Gallais-During, F. Delage, S. Béjaoui, S. Lemehov, J. Somers, D. Freis, W. Maschek, S. van Til, E. D'Agata , C. Sabathier: Outcomes of the PELGRIMM project on Am-bearing fuel in pelletized and spherepac forms, https://doi.org/10.1016/j.jnucmat.2018.10.016
2. S. van Til, P.R. Hania, A.V. Fedorov, E. D’Agata , D. Freis, S. Bejaoui, F. Delage, A. Gallais-During: Irradiation performance and first examinations of Americium bearing blanket fuel from the MARINE irradiation experiment, https://doi.org/10.1016/j.jnucmat.2023.154699
3. E. de Visser – Týnová, J. Bruin, F. Oud: Fabrication and dissolution of americium plutonium oxide fuels, https://doi.org/10.1051/epjconf/202531701001

This research was performed as a part of the European project “Fuel Recycle and Experimentally Demonstrated Manufacturing of Advanced Nuclear Solutions for Safety (FREDMANS, Grant agreement ID: 101060800)”. The Dutch ministry of economic affairs and climate is acknowledged for the co-financing of this research.emphasized text

Speaker: Eva De Visser - Týnová (NRG PALLAS & FNSPE, CTU Prague)

2:00 PM Spent Nuclear Fuel Reprocessing in Accelerator Driven Advanced Nuclear Energy System

Nuclear energy has emerged as a pivotal and effective technology to address the global energy crisis and mitigate climate change. However, the large-scale deployment of nuclear energy has resulted in the generation of substantial quantities of spent nuclear fuel (SNF), which comprises dozens of chemical elements. Specifically, SNF contains approximately 95% unutilized uranium, 1% plutonium, 0.1% minor actinides (MAs), and 3% fission products (FPs), along with other trace components. Hence, spent fuel reprocessing is essential for the sustainable utilization of nuclear energy and the realization of a closed nuclear fuel cycle. To achieve this goal, a reliable spent fuel recycling strategy is urgently required. Such a strategy should not only maximize the energy utilization efficiency of nuclear fuel by efficiently recovering actinide (An) species but also minimize the volume of radioactive waste requiring geological disposal, while also meeting nonproliferation standards.
To meet the strategic requirements for the sustainable development of nuclear energy, the concept of an accelerator-driven advanced nuclear energy system (ADANES) has been proposed in China. ADANES consists of a burner system and a fuel recycle system. By taking the powerful exogenous neutrons of ADANES, transmutation, proliferation and power generation will be implemented in the burner system simultaneously. The spent nuclear fuel reprocessing and regeneration for accelerator driven advanced nuclear energy system (ADANES) have been investigated in our laboratory for several years. Here, high-temperature oxidation volatilization technology was adopted as the core technology. Specifically, volatile and semi-volatile fission products (e.g., ³H, ¹⁴C, Kr, I, Xe, Mo, Tc, Ru, Te) can be efficiently removed through high-temperature oxidation and reduction processes. Moreover, this reprocessing procedure is not necessary to separate the long-lived minor actinides Np, Am and Cm finely. The rest spent nuclear fuel including some fission products would be refabricated as new nuclear fuels by referring to the preparation technologies of UO2 fuel. At present, the research work focuses on the simulated spent nuclear fuel to verify the feasibility of the proposed reprocessing technology. Furthermore, ADANES possesses inherent safety characteristics due to the operation control of accelerator.

Speaker: Fangli Fan

2:20 PM Spent fuel surrogate with embedded caesium iodide

Understanding the behaviour of fission products (FPs) is critical for advancing nuclear reactor safety and optimising radioactive waste management. This contribution presents preparation and characterisation of simulated nuclear fuel pellets based on uranium dioxide doped with volatile FPs - caesium and iodine - using spark plasma sintering (SPS). Compared to conventional sintering, SPS enables densification at lower temperatures and with shorter dwell times, facilitating the retention of temperature-sensitive species. The produced simfuel pellets are analysed via scanning electron microscopy (SEM), powder Xray diffraction (PXRD), and energy-dispersive X-ray spectroscopy (EDS), confirming successful incorporation of Cs and I. The pellets exhibit sufficient integrity, density, and some microstructural variability for subsequent release testing. The results aim to support predictive models of FP release under severe accident conditions, or fuel behaviour under the repository conditions.

Speaker: Václav Tyrpekl

2:40 PM Self-Radiolysis of Tritiated Water

Heavy water and lithium containing molten salt moderated commercial fission energy generating reactors produce tritium in significant quantities. Tritium, the radioactive isotope of hydrogen, needs to be removed from the moderator to reduce worker exposure, environmental release and maintain energy conversion efficiency.
Future commercial fusion power plants will operate using Deuterium & Tritium as a fuel while breeding tritium from lithium to refuel the system. The scale of tritium handling has never been performed or demonstrated.
Tritiated water can be generated in situ to a reactor like the CANDU heavy water moderated reactor case, but also through atmospheric recovery from any system that handles tritium. A common method of high flowrate sequestration of tritium is via oxidation and capture on desiccants, or in liquid water scrubbers.
The presentation will outline the possible production pathways of tritiated water in different systems. The kinetic process of tritiated water self-radiolysis and its impact on tritiated water handling systems and long-term storage. A summary of CNL’s work on the storage and handling will be presented concluding with recommendations and guiding philosophies on tritiated water handling and storage.

Speaker: Todd Whitehorne (Canadian Nuclear Laboratories)

3:00 PM → 3:30 PM Coffee break

3:30 PM → 5:00 PM Environmental Radioactivity: RER 1

Conveners: Jakub Kaizer (Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava), Michal Fejgl (National Radiation Protection Institute)

3:30 PM Determination of ⁹⁰Sr and Pu isotopes in soil samples from various regions in Austria over the last twenty years

As part of the laboratory-based environmental monitoring, the Austrian Agency for Health and Food Safety regularly determine the content of radioactivity in various media. In accordance with this official environmental monitoring program, the following media are analysed: air, precipitation, surface water, sewage sludge, wastewater from sewage treatment plants, soil, vegetation, animal feed and fertilisers. High resolution gamma spectrometry is used for most determinations, while radionuclides requiring radiochemical separation – specifically Sr-90 and plutonium isotopes – are analysed in selected samples. Although measurements of Sr-90 and Pu isotopes in soil do not provide a direct assessment of population exposure, they are essential for establishing reliable baseline levels. These baseline data are critical for the detection and evaluation of additional contamination in the event of a radiological release in the future. Many of Austria's neighbouring countries operate nuclear power plants. In Austria detailed emergency plans, a catalogue of measures, and a sampling plan have been developed and continuously updated since the Chernobyl accident (absorbing also experiences from Fukushima in 2011). The emergency plans at the federal and state levels also include the determination of Sr-isotopes and Pu-isotopes.
Strontium and Plutonium are separated using the Sr®Resin by Triskem International. Plutonium is measured by alpha spectrometry and Sr-90 is measured by Liquid Scintillation Counting.
In this presentation we will present activity concentration data from various environmental settings, including forest ecosystems, undisturbed grassland sites and alpine regions. Furthermore, the results of soil profile measurements will be presented. Understanding local and regional variability is essential for accurate data interpretation and for establishing robust baseline values.
These measurements were funded by the Federal Ministry of Agriculture and Forestry, Climate and Environmental Protection, Regions and Water Management.

Speaker: Claudia Landstetter (AGES)

3:48 PM Development and Technical Enhancement of Real-Time Monitoring Networks for Nuclear Emergency Response in the Czech Republic

System of emergency monitoring of artificial radioactivity in the environment in the Czech Republic is based on the scheme created for routine monitoring. That means, that picked samples are analysed by the lab procedures, only frequency of sampling and sensitivity of the procedures is adjusted according to Decree 360/2016. Radiation events from previous years brought evidence, that monitoring techniques with enhanced time resolution employed as supplementary monitoring tools can bring indispensable information (Masson et al., 2019).
A natural consequence of the increased likelihood of radiation risk observed in recent years is the development of various types of monitoring units for determining artificial radioactivity in the environment, as well as the subsequent installation of sensor networks.
A pilot network of aerosol samplers capable of real-time determination of artificial gamma activity in atmospheric aerosol was supplemented by networks of the following three types of real-time measuring devices in the subsequent years: submersible surface water gamma probe (Fejgl and Hýža, 2019); rain water collector determining artificial gamma activity; ambient dose equivalent (H*10) monitoring station (ZV) with the ability to identify source radionuclides and their spatial distribution.
The last two devices are prone to contamination from atmospheric fallout, what makes them difficult to work well in the event of radiation accident. Series of experiments with the aim of reinforcement their capabilities under severe conditions were performed.
Rainwater collector is based on 5L through-flow Marinelli beaker equipped with 2inch NaI(Tl) detector. Both energy and efficiency calibration were conducted for different radionuclides (Cs-134,Cs-137, I-131, Co-60) in multiple volumes within full volume range of the Marinelli beaker. The contribution of surface contamination was determined in experiments exploiting Tc-99m.
The Groud-Air monitoring station consists of two NaI(Tl) probes, which distinguish between photons originating from the air and the ground, and two Geiger-Mueller detectors utilized for the detection of atmospheric contamination. Both energy and efficiency calibration were conducted for different radionuclides (Cs-137, I-131, Co-60). An alternative approach for surface contamination determination using response of ground facing NaI(Tl) probe was developed. Several radioactivity dispersion experiments, including the determination of deposition distribution, were performed using Tc-99m and ultrasonic aerosol generators. Experiments were carried out in a controlled environment.
The conference contribution focuses on the determination of the most important gamma-emitting radionuclides under nuclear accident scenarios, with emphasis on detection sensitivity and time resolution.
This work was supported by institutional funding from the Ministry of the Interior of the Czech Republic.

Speaker: Michal Fejgl (National Radiation Protection Institute)

4:06 PM Seasonal Trends in Radionuclide Concentrations in Austrian Aerosols

Based on the Euratom Treaty Austria has established a comprehensive and thorough environmental monitoring programme. As part of this programme, the levels of radioactivity are regularly determined in various types of environmental media. Air and air filters are among the most frequently examined environmental media. Within the routine monitoring of air filters the Austrian Agency for Health and Food Safety focuses on the determination via gamma spectrometry. Besides the activity concentrations of gamma emitters, various artificial alpha and beta emitting radionuclides like the Plutonium isotopes or Sr-90 are of interest as well. Consequently, the goal of this project was to determine the activity concentrations of the alpha-emitting Plutonium isotopes Pu-239 and Pu-240, Am-241 and Sr-90 in Viennese aerosol filters. Due to the very low concentrations of these radionuclides in air (on the order of a few nBq/m³), the analysis of aerosol filters is particularly challenging. In order to achieve values above the limit of detection, filters from a high-volume air sampler with a throughput of about 700 m³/h and a sampling interval of one week were analysed. During the sampling process naturally occurring nuclides like Pb-210 become highly enriched and interfere with the radiochemical separation. Thus, the analysis becomes even more complex. In order to overcome these challenges, a sequential radionuclide separation procedure using extraction chromatographic resins was applied. While Sr-90 was measured using LSC, the Pu-isotopes were determined by alpha spectrometry. In addition to these radiometric methods, ICP-MS/MS was also used for the determination of Pu-239. The radiochemical separation procedure as well as the results of this project will be presented.
This project was funded by the Federal Ministry of Agriculture, Forestry, Regions and Water Management of Austria.

Speaker: Rainer Kadan (AGES)

4:24 PM Electrolytic enrichment for low-level tritium measurements for environmental monitoring

Low level tritium measurement has become a critical challenge for environmental monitoring. As environmental tritium concentrations have continuously decreased since the peak following the nuclear tests of the 1950s and 1960s, environmental monitoring laboratories must adapt their analytical methods to meet this new challenge. Using direct measurement, the performance of standard liquid scintillation counters is no longer sufficient to achieve the minimum detection limit (0.3 Bq/L) required for some samples. In 2025, the French Nuclear Safety and Radiation Protection Authority (ASNR) analyzed approximately 2000 samples of water for 3H measurement, of which 30 % had result below the detection limit. To increase the proportion of significant results while maintaining the ability to process large numbers of samples, an alternative approach had to be found. Electrolytic enrichment has proven to be an effective solution in many hydrology laboratories and already in some environmental monitoring laboratories. Its relevance has further increased given the recent upgrades made possible by proton exchange membrane (PEM) technology.

Because tritiated water has a slightly higher binding energy than H2O water molecules, electrolysis can be used to selectively enrich tritium. After a few hours of electrolysis with PEM cells, the sample volume decreases while the concentration of tritiated water increases. The detection of low activities of tritium is then possible with standard liquid scintillation counters. To find the initial activity, an enrichment factor (EF) must be applied. To determine it, the most commonly used approach consists of measuring tritium standards before and after electrolytic enrichment in order to calculate a cell-specific value that can be applied to unknown samples. However, it is also possible to use the enrichment of the deuterium. In this work, a new method for deuterium measurement using ICP-MS rather than laser spectrometry will be presented. Electrolytic enrichment is a robust and reliable technique, enabling the laboratory to achieve detection limits below 0.3 Bq/L with two days of enrichment.

This presentation will outline the comprehensive 3H monitoring strategy currently employed at ASNR. It will then introduce the electrolytic enrichment method currently developed at ASNR, highlighting the installation and use of the PEM cell, as well as the challenges encountered in achieving the targeted performances. Finally, a description of the EF determination will be presented, comparing the spiked method and the deuterium method.

Speaker: Paul Masselot (ASNR)

4:42 PM Recent applications of accelerator mass spectrometry in environmental studies and radiopurity measurements at CENTA

In 2022, the tandem accelerator laboratory of the Centre for Nuclear and Accelerator Technologies (CENTA) of the Comenius University in Bratislava was upgraded with a new accelerator mass spectrometry (AMS) beam line. A combination of a fast-bouncing system, high-resolution magnet, together with offset Faraday cups, two electrostatic analyzers and a multi-layer ionization chamber enable to sensitively and precisely detect isotopic ratios for several long-lived radionuclides, e.g., 10Be, 14C, 26Al, 129I, 232Th, and 238U. Some of the mentioned species can be utilized as tracers for studying different environmental processes or are important targets for radiopurity material analyses which are essential for background evaluation of underground experiments searching for rare nuclear decays and dark matter. We shall present our recent AMS measurements of 14C in hydrocarbons in the atmosphere for better understanding of its gaseous constituents, in atmospheric carbonaceous aerosols for the determination of fossil-fuel and biomass fractions, in spot sampled atmospheric carbon dioxide for the assessment of the local source impact and of 129I in precipitation for the evaluation of the influence of regional (continental) nuclear facilities. On top of that, we shall talk about developments in ultra-low 232Th and 238U concentration measurements by AMS which has potential to become the most sensitive technique for radiopurity material screening.

Speaker: Dr Jakub Kaizer (Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava)

3:30 PM → 5:00 PM Separation & Speciation: SEP 1

Conveners: Andreas Geist (Karlsruhe Institute of Technology (KIT)), Jiří Janda (-)

3:30 PM Extraction chromatographic separation of all actinides using single or stacked columns

Methods for the determination of all actinides including thorium, uranium, neptunium, plutonium, americium and curium are of major importance for nuclear chemical technology, radiation protection and environmental control. Combined separation procedures, whatever measurement technique is joined to them, make the analysis time shorter, allow the complex analysis from single sample aliquot and assure an inherent selectivity for each actinide over other possible interfering ones.
Extraction chromatography (EC) for the separation of actinides has got a wide-spread application after actinide-specific resins became commercially available (e.g., EiChrom, Triskem). Our laboratories have been involved in in-house method development for decades. In the presentation, we will show our approaches for the development of procedures for all actinides using single resin columns or a combination of two (stacked) resin columns.
An a priori selection of the appropriate resin for the analytical purpose is based on the equilibrium distribution coefficients (Dw) of the actinides. For retaining the actinides on a resin from complex matrices high Dw values are desirable. For stripping the actinides, low Dw values are advantageous, and differences in the Dw values among actinides have to be maximized. These contradictory goals can often be achieved by strict control of actinide oxidation states, formation of specific complexes, and influencing the kinetics of the process, e.g., by changing the separation temperature, mostly under on-column conditions.
We developed two separation schemes for all actinides using a single chromatographic column. The 1st resin that had acceptable high Dw values for the tri-, tetra- and hexavalent actinides was TRU resin containing carbamoylmethylphosphine oxide (CMPO). The weak link of the procedure was the limited retention of Am-Cm. Therefore, only a “rapid” procedure was developed for small samples (soil up to 1 g). DGA resin containing diglycolamide proved to be a much stronger extractant for trivalent actinides while retaining tetravalent, and to lesser extent, hexavalent ones as well. The method developed can be used for the simultaneous separation of all actinides from bigger samples (up to 100 mL liquid waste, 5 g soil), but the interfering Ca has to be removed before the chromatography. This procedure is sensitive to changes in conditions [1].
To obtain more robust separation, two-column procedures were developed for the analysis of all actinides from about 1 liter of water (tap, sea). In the TEVA-TK221 method, the TEVA resin (containing quaternary amine) of high Dw values for tetravalent actinides, sequentially separated Th, Pu(IV) and Np(IV). For the separation of hexavalent U and trivalent Am-Cm, the TK221 resin containing CMPO and DGA extractants is used [2]. Finally, it will be discussed how the latter separation scheme had to be modified when TEVA resin was replaced by TK201 resin containing a similar organic amine extractant.

[1] Vajda N, Zagyvai M, Groska J, Bokori E, Molnár Zs, Braun M (2020) Determination of uranium, plutonium and americium in soil and sediment by a sequential separation procedure using a single DGA column, J. Radioanal. Nuclear Chem., 326(1); p. 695-710.
[2] Papp, I, Vajda, N, Happel, S (2022) An Improved Rapid Method for the Determination of Actinides in Water, J. Radioanal. Nuclear Chem. https://doi.org/10.1007/s10967-022-08389-9.

Speaker: Nora Vajda (RadAnal Ltd.)

4:00 PM Speciation of Polonium in Aqueous Solutions: First insights of X-ray Absorption Spectroscopy

Polonium (Po) is receiving increasing attention due to its pronounced toxicity, natural presence in uranium-rich environments and its artificial production in nuclear industry activities (e.g. in lead-bismuth cooled fast neutron reactors). This has led to a real need to understand the chemical behavior of Po in various environments, especially since that the aqueous chemistry of Po remains poorly understood. The knowledge about the Po species formed in solution has primarily originated from indirect partition experiments with tracer amounts of Po using e.g., solvent extraction or ion-exchange. These studies often lead to conflicting interpretations of the results due to the lack of a direct structural characterization of Po species present. Notably, the direct characterization of aqueous Po species is very challenging due to its scarcity, and only a limited number of attempts have been reported regarding the structural characterization of the polonium complexes in solution. Consequently, even the nature of Po chlorido complexes remains controversial, this is despite being one of the best studied aqueous species of Po. Chloride is expected to be an important inorganic ligand for Po with regard to e.g., its mobility in highly saline environments and its behavior during industrial processes involving naturally occurring radioactive material. X-ray absorption fine structure spectroscopy (XAFS) is a powerful technique which enables to get speciation information about species formed in solution, nevertheless, it has never been used to study the speciation of Po. Therefore, the aim of the presented study was to carry out the direct experimental characterization of Po chlorido complexes in aqueous media by XAFS.

In this work, microgram amounts of Po (mainly ²⁰⁹Po) were obtained by the irradiation of a bismuth target with a 16 MeV deuterium beam and its further processing with successive solvent extraction and extraction chromatography. The multiple separation steps resulted in the decrease of the Bi content in the Po source low enough to prevent the strong interference of the Bi L₃ edge during XAFS measurement, giving access to the Po L₃ edge. This enabled to record successfully for the first time the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) at the Po L₃ edge. A combination of EXAFS obtained for Po in a highly acidic chloride solution and complementary DFT calculations revealed new structural information about the polonium chloride complexes formed. The developed approach paves the way towards the study of the speciation of Po with XAFS which will help to expand our fundamental knowledge and understanding of the aqueous chemistry of polonium.

Speaker: Paul Dutheil (Université de Strasbourg, CNRS, IPHC UMR 7178, 23 Rue du Loess, 67200, Strasbourg, France)

4:20 PM Optimization of ⁹³Mo radiochemical method for radioactive waste characterization: Improved Analytical Performance and Understanding on Separation Mechanisms

Molybdenum-93 is a long-lived (t½= 4839(63) y) activation product of increasing relevance for radioactive waste management, yet its determination in complex matrices remains analytically challenging due to its photon and electron emissions (QEC ≈ 406 keV dominant K‑shell X‑rays around 16.5–16.6 keV with associated Auger/conversion electrons) and interferences from chemically similar radionuclides, notably ⁵⁵Fe (QEC ≈ 231 keV, K‑shell X‑rays at ∼5–6 keV with Auger electrons) and ⁶³Ni (Qβ ≈ 67 keV, pure low‑energy β emitter), which have significant overlaps in liquid scintillation counting (LSC) spectra.

In this work, we present an optimised analytical procedure for Mo‑93 determination based on consecutive anion‑exchange chromatographic separation and LSC measurement. Parameters such as separation time, chemical recovery, removal of interferences, efficiency calibration for LSC were investigated and optimized.

Specifically, a detailed elution profile study was performed, enabling a reduction of the total eluent volume while maintaining high chemical recovery of Mo. An aging test was conducted to evaluate the stability of the separation procedure and to quantify potential Mo losses during sample storage and evaporation. In parallel, high‑resolution LC‑ESI‑Orbitrap‑MS was employed to characterise Mo(VI) speciation after column separation and subsequent evaporation of the purified Mo eluates, and to better understand Mo behaviour and mechanism during the separation.

Application of the final optimised procedure to real radioactive waste samples of different types (filter, resin, and metallic waste) yielded Mo recoveries of approximately 50±16% and decontamination factors for key interferents (notably Co, Ni, and Fe) that are compatible with reliable determination of low Mo‑93 activities.

Speaker: Matic Dokl (Technical University of Denmark)

4:40 PM Chromatographic separation of ¹⁰⁷Pd for characterization of radioactive waste

Pd‑107 is the second longest‑lived fission product after iodine‑129, with a half‑life of 6.5 × 10⁶ years. Owing to its persistence and radiological relevance, reliable quantification of Pd‑107 is essential for assessing inventories in spent nuclear fuel and high‑level radioactive waste. Since Pd‑107 is a pure β‑emitter with a maximum β‑energy of 34.1 keV and lacks γ‑emission, its analytical determination relies on β‑particle detection or mass spectrometry. The long half‑life favours mass‑spectrometric techniques, which allow lower detection limits and require smaller sample quantities. However, accurate analysis is hindered by isobaric interference from stable Ag‑107, making an effective chemical separation step indispensable.

In this study, we report current progress in development of a method for efficient determination of Pd-107 in radioactive waste, which is based on column extraction chromatographic separation based on TK200 Resin or Ni Resin for separating of Pd from Ag and achieving the required separation factor for mass spectrometric determination of Pd-107. Experiments involved testing and optimization of separation performance of both extraction chromatographic resin, as well as optimization of ICP-QQQ-MS measurements. Special emphasis was devoted to try to utilize capability of ICP-QQQ-MS reaction cell for removal of Ag-107 isobaric interference by introduction of different inert or reaction gases.

The obtained results reveal that Ni Resin provides the most efficient and reproducible separation performance. The results of measurements with ICP-QQQ-MS reveal that there are limited possibilities of utilizing different reaction gases to improve separation of Ag from Pd during measurement as in most studied cases both elements behave similarly. Therefore, the most important is to separate Pd from Ag efficiently before introduction to ICP-QQQ-MS instrument, although utilization of reactive gases might improve overall method performance.

Acknowledgements:
This work was co-funded by the European Union under Grant Agreement n°101166718 and the Slovenian Research and Innovation Agency programme P1 0143 and P2 0075.

Speaker: Marko Štrok (Jožef Stefan Institute)

5:15 PM → 6:30 PM Actinoids and Transactinoids: Poster session

5:15 PM Investigation of Thorium Oxide Reaction Products with Halides by XRD

Thorium has attracted renewed interest as a potential nuclear fuel due to the limited availability of uranium resources and the increasing global demand for sustainable nuclear energy. In the thorium fuel cycle, fertile $^{232}$Th can be converted into fissile $^{233}$U through neutron capture and subsequent $\beta^-$ decays. Thorium dioxide (ThO$_2$) is typically used in mixed oxide fuels (Th-MOX) together with fissile materials such as UO$_2$ or PuO$_2$. However, the high chemical stability of ThO$_2$ leads to extremely slow dissolution percent, posing significant challenges for the reprocessing of thorium-based fuels.
In addition to its energy applications, $^{232}$Th can serve as a source of the alpha-emitting radionuclide $^{225}$Ac, which is highly promising for targeted alpha therapy due to its emission of four α-particles per decay. Direct production of $^{225}$Ac from $^{232}$Th via high-energy proton irradiation, however, requires intense irradiation and may generate unwanted radioactive byproducts, such as $^{227}$Ac, which complicate its medical application. We proposed an alternative route using the naturally occurring $^{228}$Ra impurity in $^{232}$Th, where a single neutron capture followed by successive $\beta^-$ decays produce $^{229}$Ac and $^{229}$Th efficiently. This method is advantageous because it simplifies the reaction, enables rapid generation due to short-lived intermediates, and uses abundant source material. Efficient dissolution of ThO$_2$ remains essential for separating $^{228}$Ra and realizing $^{225}$Ac production.
Due to the high chemical stability of ThO$_2$, which is difficult to dissolve in acid or alkali solutions, we applied a thermochemical conversion method, heating ThO$_2$ with different halides (CBr$_4$, AlBr$_3$, CCl$_3$CCl$_3$) at elevated temperatures. The reaction products were subsequently dissolved in concentrated nitric or hydrochloric acid, and the thorium concentration in solution was measured by ICP-MS to calculate the dissolution percent. To avoid handling radioactive ThO$_2$ directly, we first performed simulations using CeO$_2$, a common surrogate for tetravalent actinide oxides, to optimize reaction conditions. The results indicated that heating at 300 °C for 12 hours was sufficient to convert most CeO$_2$ into soluble cerium halides. Based on these conditions, ThO$_2$ and the halides were reacted in sealed containers at 300 °C for 12 hours, achieving dissolution percent above 70%, with the ThO$_2$-CBr$_4$ system reaching up to 90%.
However, the reaction mechanism between ThO$_2$ and the halides remains unclear. The reaction products were therefore analyzed by XRD. The products were highly hygroscopic, sample preparation and measurement are ideally performed in a glovebox; if a glovebox is not available, faster scans over a limited angular range are recommended. The XRD patterns did not match standard ThBr$_4$ or ThCl$_4$, nor were they found in available databases, possibly due to hygroscopic changes during measurement or the formation of thorium oxyhalides. Notably, the XRD results of ThO$_2$-CBr$_4$ were essentially identical to those of ThO$_2$-AlBr$_3$, suggesting the formation of the same thorium halide species. These findings provide valuable insights into the reaction mechanism of ThO$_2$ with halides and support the development of effective ThO$_2$ dissolution strategies.

Speaker: Feng Yin (Institute for Radiation Sciences, The University of Osaka)

5:18 PM Extraction behaviour of non-complexed ultra-trace amounts of homologues of dubnium

Transactinides, also known as superheavy elements, represent an intriguing and yet almost unexplored part of the periodic table. The study of their properties is an extremely difficult task due to the very low yields in their synthesis and their extremely short half-lives, which make any experimental investigations much more complicated. Studies of these elements therefore rely on comparisons with theoretical predictions and on experiments with their lighter homologues, which can provide insights into the behaviour of superheavy elements themselves or highlight differences caused by relativistic effects. These effects can lead to unusual properties of heavy nuclei and, consequently, to deviations from the periodic law.
This work has aimed to investigate the extraction properties of cyclotron-produced tantalum (Ta), as a lighter homologue of dubnium (Db), in ultra-trace amounts produced via the reaction $^{\mathrm{nat}}$Lu($^3$He,$x$n)$^{173,174,175}$Ta. The selected extraction system utilised HNO$_3$ (0.001-13 M) as the aqueous phase and Cyanex 272 (0.5 M) as the organic phase. The organic phase also consisted of kerosene as a solvent and 1-octanol (5% v/v), an additive for better phase separation. The behaviour of the extraction system was observed under different conditions of concentrations of the aqueous phase and contact times between the two phases. The examined parameter was the distribution coefficient, which expresses the ratio of the total analytical concentration or the count rate of the isotope in question in the organic phase to the same quantity in the aqueous phase. Extraction data in suspected equilibrium revealed that higher amount of Ta, presumably in its neutral hydrolysed form, e.g., Ta(OH)$_5$, or even TaO$_2$OH, was extracted from 0.03 M HNO$_3$ when compared to its imminent surroundings. Higher extractability was also observed in higher acidities, which can be associated with a possibility of formation of extractable ionic associates with the extraction agent.
These experiments have also been performed with HCl to study chloride formation and extraction in the same system. Nevertheless, cyclotron products transported via KCl aerosols on filter paper were not dissolved in a wide range of HCl concentration effectively. Experimental data for both acids, however, suggest that dissolution of Ta or its chemistry in general might be hindered by the formation of Ta radiocolloids even in such small concentrations. Within the near future, the objective is to ensure the reproducibility of the process, thus eliminating the potential impact of impurities and sorption processes of Ta at ultra-trace levels, possibly finding a strong non-fluoride chelating agent.

Speaker: Kateřina Havelková (FNSPE CTU)

5:21 PM Studies on parameters affecting uranium leaching from granite

The effect of various chemical parameters such as ligand type: citric acid, EDTA, NO3- and HCO3-, their concentration and pH on the uranium leaching from granite samples has been investigated by means of batch-type experiments. The total uranium concentration in the solution after 60 days was analyzed by ICP-OES. Very high leaching rate of uranium was observed in citric acid and EDTA, followed by carbonate and nitrate close to that achieved in water. The ligand concentration (0.01 M and 0.001 M) appears to greatly enhance the leaching efficiency at the studied ligand concentrations especially for organic ligands. The effect of pH was studied using 0.01 M ligand solutions with different pH (EDTA (pH= 4.5), EDTA salt (pH=6.5), citric acid (pH=2.5) and citric acid salt (pH=6)). The highest leaching rate in both the EDTA system and the citrate system is observed in the acidic solution.

Speaker: Nektaria Varnava (Department of Chemistry, University of Cyprus)

5:24 PM Thioalkane-Based Self-Assembled Monolayers for Surface Functionalization in Superheavy Element Detection

Research on self-assembled monolayers (SAMs) has led to the emergence of a new material research area that enables the preparation of surfaces with chemically tunable properties. The aim of this work is to study and develop a selective SAM-based system exhibiting suitable sorption properties toward selected radionuclides, with potential applications for the detection of superheavy elements (SHEs) through the functionalization of semiconductor detector surfaces. The motivation for this approach is the possibility of trapping atoms in close proximity to the detection surface, which would allow for their detection directly in the liquid phase, where high resolution alpha spectrometry is otherwise significantly limited by the short range of emitted particles.

First, the extraction properties of selected functionalized thioalkanes in a liquid–liquid system were studied to verify their affinity for selected metal ions. Specifically, the compounds 1-(11-mercaptoundecyl)imidazole, sodium 11-mercaptoundecane-1-sulfonate, (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide, and 11-mercaptoundecylphosphonic acid were tested. It was found that 11-mercaptoundecylphosphonic acid exhibits high extraction efficiency toward Eu3+, which was chosen as a representative of the lanthanides, while the other functionalized thioalkanes studied exhibited lower, yet non-zero, extraction efficiencies. These experiments served as a screening step for identifying functional groups capable of effectively coordinating metal ions in solutions.

Subsequently, SAMs were successfully prepared from all selected functionalized thioalkanes on gold-plated substrates. The formation of the layers was confirmed using surface characterization methods, although formation of a pure monolayer might not have been always successful. The sorption properties of the prepared SAMs toward selected radionuclides were then studied.

It was found that the sorption of radionuclides was successful for the isotopes 165Tm and 49Cr, however, it did not exhibit sufficient selectivity, as sorption also occurred on reference

chips without the presence of a monolayer. In contrast, the radionuclide 184Ir did not exhibit measurable sorption under the given conditions. The results show that although the extraction properties of ligands in solution are an important prerequisite for their use in SAM systems, the immobilization of molecules on the surface itself leads to significant steric and structural constraints that can fundamentally affect the resulting sorption efficiency and selectivity.

This work thus highlights the necessity of combining studies of extraction in solution and sorption on the surface when designing functional materials for radiochemical applications and represents a step toward the development of new detection systems for SHEs in the liquid phase.

Acknowledgment

This work was supported by CTU Student Grant SGS24/148/OHK4/3T/14.

Speaker: Lucie Bartl (Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, 115 19 Prague, Czech Republic)

5:27 PM Identification of the Neglected 1:3 Plutonium(VI)-Oxalate Complex

In this study, we scrutinized the complexation of Pu(VI) with oxalate in aqueous solution using absorption spectral titration to resolve existing controversies regarding its speciation. By employing a two-stage titration method with high concentrations of oxalate, we successfully identified the previously neglected 1:3 complex species, PuO2L34-, characterized by an absorption peak at 846.8 nm. We calibrated the stability constants for the three successive complexes—PuO2L(aq), PuO2L22-, and PuO2L34-—to be logβ1 = 5.23 ± 0.04, logβ2 = 9.21 ± 0.08, and logβ3 = 10.61 ± 0.12, respectively.
We found that the omission of the 1:3 species in previous literature likely stemmed from inappropriate spectrometer slit settings that failed to capture the sharp 830 nm Pu(VI) peak, combined with insufficient oxalate levels to drive the formation of the third complex. Our analysis reveals that while the first two oxalate ligands bond strongly through five-membered ring chelating modes, the third coordination step is much weaker, with a stepwise constant of logk3 = 1.40. This significant drop in stability leads us to conclude that the third oxalate likely bonds via a single carboxylic group in a head-on mode. These results clarify the thermodynamic behavior of plutonium in the presence of organic ligands, offering vital data for nuclear fuel reprocessing and radioactive nuclide migration research.

Speaker: Liang Xian

5:30 PM Startup of Superheavy Element Chemistry at KURNS, Kyoto Univ.

Studies of the chemical and physical properties of the elements at the uppermost end of the Periodic Table are challenging both experimentally and theoretically. One of the most important and exciting subjects is to clarify the basic chemical properties of these elements, as well as to elucidate how relativistic effects play a role in their properties.

Very recently, a new research group dedicated to nuclear and radiochemistry for the application of radionuclides has been launched at KURNS, Kyoto University, Japan. KURNS (Institute for Integrated Radiation and Nuclear Science, Kyoto University) has been contributing to education and research at both Kyoto University and in the fields of nuclear power and radiation throughout Japan as a Joint Usage/Research Center certified by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.

Heavy elements with atomic numbers larger than 100 can be produced only via heavy-ion beam-induced nuclear fusion reactions using an accelerator. The number of produced atoms is extremely small and their half-lives are very short; any experiments must be conducted on an atom-at-a-time basis, which imposes stringent limits on experimental procedures.

We have initiated research and development for the chemistry of heavy actinides and transactinides in liquid and gas phases, and for the use of their ion beams as an application of radioactive isotopes. In this presentation, the current status of the development of a novel ion source for an ISOL (Isotope Separator On-Line) at JAEA (Japan Atomic Energy Agency), liquid/gas phase chemistry studies using lighter homologues, and future perspectives will be introduced.

Speaker: Prof. Tetsuya K. Sato (Kyoto Univ.)

5:15 PM → 6:30 PM Nuclear Fuel Cycle: Poster session

5:15 PM Decommissioning Sludge Waste Solidification in Geopolymer: An Optimization of Waste Loading and Physico-Mechanical Properties

Radioactive sludge wastes generated during reactor decontamination and dismantling are complex matrices containing metal oxides, silica, carbonates, carbonaceous phases, and radionuclides such as Cs, Sr, and Co. To solidify such diverse and complex waste streams, geopolymers (GP) have emerged as a low-carbon-emitting, less porous, and robust alternative to conventional cementitious materials. They are increasingly studied as engineered barriers for cationic, anionic, redox-sensitive, and organic wastes.

In this work, a series of samples with 0, 10, 20, 30, 40, 50, and 60 wt% incorporated simulated decommissioning sludge waste to metakaolin-based geopolymer were synthesized to optimize waste loading. We investigated the physico-mechanical performance of developed waste forms against waste loading at room temperature (21 days) and at 60 °C (5 days). Initially, the apparent density, porosity, and compressive strength were used as primary performance indicators for all samples. Phase composition, microstructure, and chemical characteristics were analyzed using XRD, SEM-EDS, XRF, FTIR, and BET techniques.

The two curing regimes produced almost similar phases (BaCO3, BaSO4, and MnO2) across all decommissioning waste loadings. However, samples cured at room temperature exhibited lower compressive strength (30.91 ± 2.26 to 5.92 ± 0.98 MPa) compared to 60 °C cured samples (39.95 ± 4.66 to 8.05 ±1.28 MPa), likely due to slower reaction kinetics. In both cases, the apparent density increased almost linearly with increasing waste loading, attributed to the incorporation of heavier constituents, pore filling, and enhanced matrix compactness. Based on the physico-mechanical performance, a waste loading of 50 wt% relative to the total waste-form mass appears to be optimal for subsequent radionuclide incorporation and further characterization.

These preliminary results highlight the potential of geopolymers as durable, low-carbon waste forms for immobilizing complex radioactive sludge wastes. Ongoing studies focus on reducing the water-to-binder ratio, incorporating simulated corrosion products, and evaluating long-term leaching behavior.

Acknowledgements
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Climate, Energy & Environment (MCEE) of the Republic of Korea (No. RS-2023-00236697) and by the National Research Foundation of Korea (NRF) grant funded by the Korea Government Ministry of Science and ICT (RS-2025-02311305).

Speaker: SAJID IQBAL (Korea Advanced Institute of Science and Technology (KAIST))

KAIST_ SAJID RadChem 2026-Poster.pdf

5:18 PM pH-Dependent Synergistic Enhancement of U(VI) Transport by Phosphate and Bentonite Colloids

Bentonite colloids and phosphate exert both competing and complementary influences on U(VI) mobility in high-level radioactive waste repositories. Phosphate immobilizes uranium through precipitation, yet it also competes with pH-sensitive bentonite colloids for U(VI) adsorption. In this study, the interactions and cotransport of uranium with bentonite colloids and phosphate were examined using quartz-sand and granite-mineral columns. Results show that U(VI) transport is strongly pH-dependent. Specifically, phosphate (P) enhances U(VI) mobility through the formation of intrinsic uranyl-phosphate colloids above pH 3.0. In contrast, under more acidic conditions (pH 2.5), neither phosphate nor U(VI) can form such colloids, and thus phosphate has no influence on U(VI) transport. Although granite adsorption tends to immobilize U(VI), elevated bentonite colloids (BC) concentrations substantially increase uranium mobility, with recovery rates varying by mineral type: biotite (16.45%) < illite (44.21%) < K-feldspar (73.75%) < quartz (90.54%). Within the P–BC–U(VI) ternary system, bentonite colloids synergistically facilitates U(VI) transport by functioning as both carrier and stabilizer. An independent two-site model (ITSM) successfully reproduced the cotransport behavior by quantifying adsorption–desorption dynamics and colloid retention. These findings underscore the critical role of pH in governing radionuclide mobility mediated by environmental colloids, offering key insights for the safety assessment and transport modeling of geological repositories.

Speaker: Yanhui Wang

5:21 PM Stabilization of chloride molten salts waste by vitrification

NRG PALLAS conducts a comprehensive research program on molten salt reactor related materials, including both molten salts (both fluorides and chlorides) and structural materials. This experimental research includes irradiations in the HFR Petten, and therefore generates compositionally complex radioactive waste streams. Common for most of these streams is the fact that a suitable waste route towards safe (interim) storage is lacking. The objective of NRG PALLAS’s research on molten salt waste handling is to establish a processing route to convert the mixed molten salts to waste forms that are expected to be acceptable by the (interim) nuclear waste storage facilities. In the past, stabilization methods of fluoride molten salts have been studied [1].
The European project MIMOSA (MultI-recycling strategies of LWR SNF focusing on MOlten SAlt technology) develops and analyses multi-recycling strategies for the European Union based on the use of MSRs and demonstrates several key aspects of their technical feasibility and performance by both calculations and experimental investigations [2]. Within this project, experiments are done to establish handling methods for stabilization of the chloride MSR waste by vitrification. The conversion of a representative chloride salt composition (NaCl-MgCl2-ThCl4-PuCl3) in a laboratory setting to both a borosilicate and an iron phosphate glass was performed. In addition an oxalic acid route was used to create oxalate salts prior the vitrification step. As ThCl4 and PuCl3 were not available for this study, various representative sim-fuel compositions were tested using NdCl3 and CeCl3 as surrogates. The vitrification tests were successful and produced stabilized molten salts in glass waste forms, which is promising for the future.
References

1. Ralph Hania, Eva de Visser – Týnová, Sem Leftin, Jasper Roozee, Twan Holvast, Irene Loppersum, Arend Booij, Matthew Kong, Elisa Capelli, Ruud Hendrikx: Dehalogenation-Vitrification of Halide Spent Fuel Salt Samples from HFR Irradiation Tests, submitted to Nuclear Design and Engineering, 2025.
2. Isabelle Morlaes et al: Exploring the safety and performance of molten salt reactors for their deployment in the European Union: the MIMOSA and ENDURANCE projects, https://doi.org/10.1051/epjn/2025026

This research was performed as a part of the European project “MultI-recycling strategies of LWR SNF focusing on MOlten SAlt technology (MIMOSA, Grant agreement ID: 101061142 )”. The Dutch ministry of economic affairs and climate is acknowledged for the co-financing of this research.

Speaker: Eva De Visser - Týnová (NRG PALLAS)

5:24 PM Immobilization of ⁹⁹Tc by iron carbonate minerals

Technetium‑99 ($ ^{99}Tc $) is a radioactive fission product of the nuclear fuel cycle, with a long half-life (211,000 years). In oxidizing environments, $ ^{99}Tc $ is primarily present as the pertechnetate ion ($ Tc(VII)O_4 $), which is a highly soluble species. Due to its high mobility and long-term persistence, $ ^{99}Tc $ poses a significant environmental challenge and is treated conservatively in safety assessments for nuclear waste repositories. Under reducing conditions, however, $ ^{99}Tc $ is immobilized as Tc(IV), forming low-solubility phases such as $ TcO_2·nH_2O$ with stronger retention on mineral surfaces.

Fe(II)-bearing minerals play a particularly important role in immobilizing Tc because they are reductive species and provide reactive surfaces and lattice sites for Tc(IV) retention. Fe(II)-minerals are naturally present in the host rock or formed over time from the corrosion of nuclear waste steel canisters. However, transport calculations employed in safety assessments generally neglect solubility-reducing processes associated with Fe(II) phases. A more detailed understanding of Tc(VII) behavior in contact with corrosion products, especially iron(II) carbonates, is therefore essential to reduce overly conservative assumptions in long-term safety assessments.

This study investigates $ ^{99}Tc $ reductive immobilization through interaction with iron carbonate minerals, namely natural ankerite $(Ca(Fe,Mg,Mn)(CO_3)_2)$, and synthetic siderite $(FeCO_3)$. Prior to the experiments, the minerals were characterized using Mössbauer spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD) to assess their morphology and confirm phase purity. Batch sorption experiments were conducted to evaluate the effects of $ ^{99}Tc $ concentration, carbonate content, pH, and ionic strength under anoxic conditions in a glovebox. For a molecular understanding, $ ^{99}Tc $ retention will be studied using Raman spectroscopy and X-ray absorption spectroscopy. First results show that siderite has a higher affinity (99.8%) and faster kinetics (72 h) for Tc immobilization than ankerite (13.1% after 30 days).

Speaker: Zarina Salkenova (Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstraße 400, 01328 Dresden, Germany)

5:27 PM Evaluation of tungsten activation by neutrons generated during D+D nuclear fusion reactions

The KSTAR device is a superconducting nuclear fusion research facility that conducts deuterium + deuterium fusion experiments. The reaction occurs in a 50:50 ratio, as shown below:

• D + D → He-3 (0.82 MeV) + n (2.45 MeV)
• D + D → T-3 (1.01 MeV) + p (3.02 MeV)

The 2.45 MeV neutrons generated during this process irradiate surrounding devices, which then decay according to their physical half-life. The radiation generated during this decay serves as a source of radiation exposure for radiation workers during maintenance.
The KSTAR device is equipped with a PFC (Plasma Facing Component) to protect the vacuum vessel from plasma. Plans are underway to coat the PFC's surface with tungsten for operation. We will conduct an evaluation to identify regulatory issues and the extent of increased radiation exposure to workers, and present the results to develop an operational plan. The KSTAR device's design requirement of 1.2 x 1020 neutrons per year will be used as the basis for the evaluation. The general reaction equation for the stable isotope tungsten (W) capturing a neutron to produce a heavier isotope (W*) is as follows, and gamma rays (r) are generated:

ZAW + n ->Z A+1W + r

Isotopes such as 181W, 185W, and 187W, produced through this neutron capture reaction, are radioactive nuclides with relatively long half-lives, and are expected to contribute to increased radiation exposure for workers.

Speaker: Hee Soo Kim (Korea Institute of Fusion Eenegy)

RadChem 2026 _HSKim.pdf

5:30 PM Investigating mineral sequence effects on radionuclide retardation in reactive transport models.

Modelling reactive transport (RT) in fractured crystalline rocks plays a crucial role in controlling the migration and retention of radionuclides in geological repositories. Conventional RT models typically describe the retardation of radionuclides using bulk parameters such as the distribution coefficient (Kd), which is assumed to depend primarily on average mineral composition. While this approach is computationally efficient, it neglects the fact that groundwater interact sequentially with different mineral surfaces along the flow paths within fractures. As a consequence, the order in which the different minerals are encountered along the flow path may influence the evolution of solution chemistry and the retardation of radionuclides. As this contribution shows, mineral sequence effects, defined as changes in the reactive transport behaviour, can arise solely from the order of mineral-solution interaction, even when the same minerals are present in the same amount along the flow path. The central hypothesis is that sequence effects persist under realistic subsurface conditions due to nonlinear reaction behaviour, finite reaction kinetics and limited transport times. Indeed, natural systems are characterised by slow flow velocities, heterogeneous mineralogy and kinetically limited reactions, which prevent complete equilibrium and should allow sequence-dependent effects to persist. To investigate these effects, a compartment-based reactive transport framework was developed where each mineral surface is represented as an individual compartment. A solution with fixed initial composition passes sequentially through these compartments, and geochemical interactions within each compartment is simulated using ideal equilibrium reactions modelled with PHREEQC. This stepwise modelling approach allows the cumulative impact of mineral sequence on sorption and retardation to be analysed under controlled conditions. It is shown that nonlinear reaction mechanisms such as surface site saturation, pH-dependent sorption, and competitive binding processes can lead to sequence-dependent retention not properly described by Kd values of average mineralogy. An important finding is that the transport of different radionuclides and other relevant interacting elements, can lead to different sequence-dependent retention.

Speaker: Liya Tomy

5:33 PM Development of an AI-Driven Intelligent Hybrid System for Real-Time Optimization and Advanced Decontamination of Metallic Radioactive Waste

In the rapidly expanding global nuclear decommissioning market, the efficacious decontamination of metallic waste is pivotal for enhancing waste management economics and ensuring operational safety. Recent pilot-scale demonstrations at the Kori Unit 1 site have validated a synergistic process—integrating ultrasonic cavitation with inorganic salt solutions—which successfully reduced surface contamination of highly active specimens to background (BKG) levels, satisfying stringent clearance criteria. However, inherent mechanical limitations in equipment design often lead to non-uniform decontamination and process inefficiencies when dealing with complex geometries and diverse surface characteristics. Furthermore, conventional manual operations, characterized by lengthy process cycles of approximately nine hours, significantly limit throughput and necessitate technical advancements to mitigate radiological risks to personnel in high-risk environments.

To address these challenges, this study presents the development of an AI-based intelligent real-time hybrid decontamination system featuring multidimensional pre-recognition and autonomous process optimization.
First, the system employs advanced sensor fusion and vision algorithms to precisely characterize the material properties, complex geometry, surface roughness, and initial radioactivity distribution of the waste prior to processing.
Second, an AI-driven predictive model, trained on empirical performance data, dynamically optimizes critical operational parameters—such as chemical concentration, ultrasonic power intensity, frequency, and duration—to establish ideal decontamination conditions in real-time.
Third, a real-time feedback loop monitors the decontamination progression to eliminate redundant cycles, automatically terminating the process upon reaching target levels to maximize throughput.

The proposed intelligent framework actively compensates for mechanical variables through AI-driven adaptability, maximizing decontamination efficiency per unit time. Moreover, the implementation of an automated system minimizes manual intervention, providing inherent safety for workers. This AI-integrated hybrid solution establishes a new technological standard for next-generation decontamination, ensuring both economic viability and safety in the global nuclear decommissioning industry.

Speaker: Dr HUIGYEONG KIM

5:36 PM Development of a virtual reality-controlled robotic arm for the retrieval of hard-to-reach objects.

The decommissioning of Nuclear Power Plant A1 represents an atypical case due to the facility’s history of accidents and its experimental character. These factors significantly complicate the decommissioning process compared with that of conventionally shut-down nuclear power plants. An illustrative example of this complexity is the handling of the contents of a vessel located beneath the reactor hall. The vessel was accessible only through a floor opening in the reactor hall with a diameter of approximately 15 cm. Inside, fallen objects exhibiting dose equivalent rates ranging from tens to hundreds of mSv/h were present.
Safe decommissioning required retrieval of these objects. To achieve this, a mechanically articulated arm with multiple degrees of freedom was developed and operated via a virtual-reality interface. Compared to conventional camera-based control, the VR system enabled enhanced spatial awareness and more precise manipulation in the confined, high-radiation environment. Using this approach, the objects were successfully retrieved, characterized, and securely stored while significantly reducing the individual effective doses received by workers during decommissioning of the vessel.

Speakers: Mr Boris Andris, Pavel Nykl

5:39 PM Fixation of Non-Standard Intermediate-Level Liquid Radioactive Waste from NPP A1

The Nuclear Power Plant A1 is approaching the final stage of decommissioning with respect to legacy waste materials. The radioactive waste currently under treatment ranges from very low-level radioactive waste (VLLW) to intermediate-level radioactive waste (ILW). One category of ILW scheduled for near-term treatment is liquid waste stored in a manipulation and storage tank.
This liquid waste represents a complex heterogeneous mixture comprising an inorganic phase (potassium chromate and potassium dichromate – Chrompik), an organic phase (Dowtherm), sludge, and mechanical components such as metal shavings. The formation of this mixture is attributed mainly to improper handling of spent fuel casks containing Chrompik and Dowtherm, while its treatment is further complicated by presence of corrosion products and radiolysis-induced precipitation of chromium (III) oxide.
To enable safe conditioning and disposal, a fixation formulation was developed specifically for this waste stream. The ILW is incorporated into a cement-based composite matrix with water and an organic polymer additive (Nochar N910), ensuring effective immobilization of both organic and inorganic components. Compliance with acceptance limits and storage conditions for disposal in a repository in the Slovak Republic is ensured through long-term monitoring of key waste-form properties, including leachability, mechanical strength, and rheological properties.

Speakers: Mr Boris Andris, Pavel Nykl

5:42 PM Radionuclide sorption efficiency depending on the basal-to-edge surface ratio of muscovite

Ensuring the long-term safety of nuclear waste repositories requires understanding the potential migration of radionuclides into the biosphere. Adsorption onto mineral surfaces, particularly phyllosilicates such as mica, plays a critical role in inhibiting this migration. However, mineral surfaces undergo surface reactions, such as dissolution, that modify surface nanotopography by changing the ratio of basal (001) to edge (hk0) faces and potentially impact radionuclide sorption efficiency.
Previously, a numerical approach on radionuclide sorption on muscovite showed that there is a large difference between the adsorption probability on the basal (001) muscovite surface and the edge (hk0) face with sites found in the {hk0} contribution being preferential adsorption positions.[1]
In this study, we investigate the quantitative effect of dissolved crystal surfaces on sorption efficiency, which is neglected in batch experiments[2]-[4] that use crystal powder as the substrate for sorption reactions.
We experimentally modified muscovite surfaces to simulate various {hk0} to {001} ratios. Then, we analyze the resulting surface topographies using vertical scanning interferometry, atomic force microscopy, and scanning electron microscopy.
Subsequently, sorption experiments were conducted with varying pH values. Autoradiography was used to quantify radionuclide adsorption across different {hk0} to {001} ratios.
The fundamental insight into varying crystal surface reactivity has applications in both natural and technical systems, enhancing our understanding of radionuclide retention in complex systems and providing critical information for the selection of safe nuclear waste disposal sites.

[1] Schabernack, J.; Oliveira, A. F.; Heine, T.; Fischer, C. Variability of Radionuclide Sorption Efficiency on Muscovite Cleavage Planes. Advanced Theory and Simulations 2023, 6 (12), 2300406.
[2] Wu, H.; Chen, J.; Su, Z.; Ma, B.; Ji, Y.; Lin, S.; Xu, D.; Kang, M. Insight into the adsorption of europium(III) on muscovite and phlogopite: Effects of pH, electrolytes, humic substances and mica structures. Chemosphere 2021, 282, 131087.
[3] Pan, D. Q.; Fan, F. Y.; Wang, Y. C.; Li, P.; Hu, P. Z.; Fan, Q. H.; Wu, W. S. Retention of Eu(III) in muscovite environment: Batch and spectroscopic studies. Chemical Engineering Journal 2017, 330, 559–565.
[4] Britz, S. M. Europium sorption experiments with muscovite, orthoclase, and quartz: Modeling of surface complexation and reactive transport. 2018.

Speaker: Sieglinde Holzknecht (HZDR)

5:45 PM Low-temperature decontamination medium for primary circuit of NPPs

During operation of nuclear power plants, corrosion products are activated in the active zone, transported by the coolant, and contaminate the inner walls of primary circuit components by adsorption/incorporation into corrosion layers formed on the material. To ensure safe operation and reduce radiation hazard for working personnel, it is essential that decontamination is carried out on regular basis. The principle of decontamination is to remove corrosion layers and release incorporated radionuclides. Corrosion layers formed on stainless steel surfaces (used in primary circuit components of Czech NPPs) consist of insoluble spinel-type compounds of Fe, Cr and Ni. In chemical decontamination methods, most efficient removal is achieved by oxidation of the compounds into higher states to produce more soluble species. Efficiency of decontamination media is usually further increased by application at elevated temperatures (70-90 °C). However, this increases the overall energy consumption of the process and, in some cases, complicates transportation of the medium. In this context, there is a strong demand for decontamination media that could achieve sufficient decontamination factors even under lower temperatures.

This work is aimed at the development of low-temperature medium for decontamination of primary circuit of Czech NPPs, which is based on previously patented medium developed for decommissioning purposes [1]. Composition of the patented medium was modified for the purposes of operational decontamination, and its efficiency was tested and confirmed on model substrates (Cr2O3, Fe3O4, Fe2NiO4). Currently, dissolution of inactive samples of corrosion layers on stainless steel materials is being assessed. In parallel, real samples from the primary circuit are being characterized and will be subjected to decontamination. Results from dissolution/decontamination of inactive and active samples will be presented.

Speaker: Jan Houzar (Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, 115 19 Prague, Czech Republic)

5:48 PM Preparation of Simulated MOX Ceramic Nuclear Fuel Microspheres by Microwave-assisted Internal Gelation Process

The rapid development of nuclear power will inevitably produce large amounts of spent nuclear fuels (SNF). In order to improve the utilization rate of uranium resources and achieve the sustainable development of nuclear energy, the closed nuclear fuel cycle must be developed accordingly. Sub-critical Accelerator Driven System (ADS) is a potential way to transmute the minor actinides (MAs) and long-lived fission products (LLFPs) into short-lived or stable nuclides by fast neutrons, and consequently reduce the difficulty of geological disposal. Based on the ADS project, Chinese academy of Sciences proposed an advanced Accelerator Driven closed Nuclear Fuel cycle (ADRUF) concept, which is a process of removing some of the fission products and neutron poisons by an advanced dry head-end processing technology while retaining U, Pu and MAs, and then refabricating the SNF into regenerated nuclear fuels. Therefore, it is of great significance to realize how to reproduce regenerated nuclear fuels from SNF in the ADRUF cycle. Because of high radioactivity and biotoxicity, an improved rapid internal gelation process combining non-cooling instant mixing with microwave-assisted heating is proposed to prepare regenerated ceramic nuclear fuel microspheres from SNF.
In order to simulate the SNF in ADRUF cycle, the preparation of multi-element metal mixed oxides (MOX) ceramic simulated nuclear fuel microspheres is also carried out in this thesis. Under the condition of 3 ℃/min, 1500 ℃ in 4% H2/Ar for 5 h, U+Ce and U+Ce+Nd oxides ceramic microspheres with a density of 95% TD are successfully prepared. The final microspheres are solid solution of faced centered cubic MO2 (M = U, Ce and Nd), and the lattice parameter decreases with increasing content of doped elements. In addition, the oxidation behavior of the ceramic MOX microspheres is also investigated, and it is found that the doped element has certain stabilizing effect on the faced centered cubic MO2 under oxidation ambient. When the content of doped element is less than 10%, the faced centered cubic MO2 can be oxidized to rhombic phase M3O8 and the microspheres are pulverized due to obvious volume expansion above 500 ℃. However, when the content of doped element is more than 20%, the cubic phase MO2 can only be oxidized to the similar cubic phase M4O9 even up to 1000 ℃, and the morphology of the microspheres keeps unchanged during the oxidation process.

Key words: Spent Nuclear fuel, Ceramic nuclear fuel microspheres, Microwave-assisted Internal Gelation Process.

Speaker: Wei Tian (Chinese Academy of Sciences, Institute of modern Physics)

5:51 PM Analysis Development at Japan Nuclear Fuel Chemical Analysis Co., Ltd (J-CAL)

Based in Rokkasho Village, Aomori Prefecture, Japan, our company is a member of the Japan Nuclear Fuel Limited (JNFL) Group and specializes in various analytical and measurement services related to nuclear fuel cycle facilities. Rokkasho Village serves as a central hub for Japan’s nuclear fuel cycle operations. To contribute to the safe and stable operation of the reprocessing facilities through our analytical expertise, we conduct analyses using a variety of analytical methods and instruments.
We are collaborating with Tohoku University to improve analytical methods that reflect the latest scientific findings. Regarding U extraction methods from high-level radioactive liquid waste, there is a lack of literature data on solid-phase extraction of such waste, and it is necessary to understand the separation behavior of impurities in the waste. Therefore, we conducted a study using simulated samples to understand the separation behavior of impurities and report the results.

Speaker: Mr Eimitsu Fujita (Japan Nuclear Fuel Chemical Analysis Co., Ltd.)

5:54 PM Adsorption and Separation of Heat-generating Elements and Platinum Group Metals from High-Level Liquid Waste using Extractant-impregnated Amberlite XAD7-HP Adsorbent

High-level liquid radioactive waste (HLLW) generated during spent fuel reprocessing contains significant amounts of heat-generating nuclides such as Cs(I), Sr(II) and platinum group metals (PGMs), posing challenges for long-term waste management. Although extraction chromatography has been widely studied for nuclide separation, conventional approaches require multiple adsorbents with high element-specificity, resulting in complex separation processes.
In this study, we evaluated a novel adsorbent impregnated with Calix[4]arene-R14, DtBuCH18C6, Crea, and TOA on Amberlite XAD7-HP for the selective adsorption of Cs(I), Sr(II), and PGMs in a simplified separation process. Batch adsorption experiments using simulated HLLW components revealed distinct selectivity toward target elements, while chemical stability in nitric acid was confirmed by TOC analysis. Furthermore, column separation experiments under temperature-controlled conditions demonstrated the feasibility of sequential separation of Cs(I), Sr(II), and PGMs, providing well-defined separation profiles.
This study presents a new approach for simplifying HLLW treatment by integrating multi-element separation into a single adsorbent system, offering a promising pathway toward more efficient and practical radioactive waste management.

Speaker: Masahiko Kubota (Tohoku University, Japan Nuclear Fuel Chemical Analysis co., Ltd)

5:57 PM From Liquid to Solid: Stabilization of Uranium Waste by PSI-Based Coagulation

Liquid wastes containing uranium compounds, such as uranyl acetate and nitrate, are generated in laboratory-scale nuclear research facilities and pose a significant management challenge, particularly in countries where centralized disposal systems for small-volume radioactive waste are not available. This study investigates the applicability of polysilicato-iron (PSI) coagulants for the treatment of low-concentration uranium-containing aqueous wastes by coagulation–sedimentation with a focus on achieving efficient removal under near-neutral pH conditions.
Cold experiments employing cerium nitrate and acetate as non-radioactive surrogates of some actinide species were conducted to evaluate coagulation behavior, followed by hot tests using uranium-containing solutions, including uranyl acetate and nitrate. Two PSI coagulants with different Fe concentrations and Fe/Si ratios (PSI-010 and PSI-025) were assessed. The results demonstrate that, unlike simple pH-induced precipitation, PSI addition enables efficient uranium removal at near-neutral pH conditions (pH 7–8), which are suitable for practical handling and discharge.
Under optimized conditions of pH and coagulant dosage, the radioactivity concentration in the supernatant was consistently reduced to well below the Japanese regulatory limit (0.02 Bq.cm-3), demonstrating regulatory compliance under practical conditions. Furthermore, the treatment process successfully converted liquid waste into a stable solid form suitable for handling and storage, achieving substantial volume and mass reductions to approximately 1 % of the original waste. Application to real mixed waste confirmed the robustness and practicality of the method.
In addition to its effectiveness, the incorporation of uranium into the solid matrix limits its re-extraction, offering potential advantages from a nuclear security perspective. These findings highlight PSI-based coagulation–sedimentation as a simple, robust, and scalable approach for the on-site stabilization and management of uranium-containing liquid waste in research and small-scale nuclear facilities.

Acknowledgment
This work was supported by MEXT Innovative Nuclear Research and Development Program Grant Number JPMXD0224020490 and by the CTU Student Grant SGS24/148/OHK4/3T/14. Part of this work was performed under the GIMRT Program of the Institute for Materials Research, Tohoku University (Projects No., 202312-IRKAC-0042 and 202505-IRKAC-0051). The authors acknowledge valuable discussion with Drs. Sakasegawa and Nishiwaki, Japan Atomic Energy Agency.

Speaker: Lucie Bartl (Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, 115 19 Prague, Czech Republic)

6:00 PM Geopolymer matrices and their behaviour under surface repository conditions

The safe management of radioactive waste relies on engineered barrier systems (EBS), where cementitious materials are commonly used to limit radionuclide migration. However, their performance may be limited in the case of mobile anionic species. Geopolymers, as alkali-activated aluminosilicate materials, represent a promising alternative due to their chemical stability, low permeability, and resistance to aggressive environments.

This work investigates the behaviour of selected anions in geopolymer matrices under conditions relevant to surface repository systems. Geopolymer samples incorporating a mixture of cation and anion exchange resins were prepared to simulate realistic waste forms. Leaching experiments were performed, and the concentrations of anions were analysed using isotachophoresis.

The results demonstrate that geopolymer matrices exhibit selective, composition-dependent retention of anions. Resin incorporation significantly influences anion mobility, enhancing sulfate retention while reducing nitrate adsorption. Increased resin loading does not lead to proportional improvements in long-term immobilization, indicating non-linear system behaviour. The observed leaching profiles suggest that transport processes are governed by a combination of surface interactions and diffusion, with long-term behaviour approaching equilibrium conditions.

These finding highlight the importance of anion-specific interactions in assessing the suitability of geopolymer matrices for radioactive waste immobilization and underline the need for system specific optimization to ensure reliable long-term performance.

Speaker: Barbora Vašková (Czech Technical University in Prague)

5:15 PM → 6:30 PM Separation & Speciation: Poster session

5:15 PM Recovery Correction and Quantitative Reliability Assessment of ⁹⁹Tc Radiochemical Analysis Using Rhenium as a Surrogate Tracer and TEVA Resin Separation

Technetium-99 (Tc-99) is a long-lived beta-emitting radionuclide of major concern in radioactive waste characterization, environmental monitoring, and nuclear facility decommissioning. Because Tc-99 is highly mobile in the environment and difficult to quantify at low activity levels, reliable radiochemical separation and accurate recovery correction are essential for precise determination. However, the direct use of an isotopic tracer such as Tc-99m is often impractical due to its short half-life and handling constraints, which limits routine application in laboratory and field analyses. Therefore, the development of an alternative and practical recovery monitoring strategy is required.

In this study, rhenium (Re), a group 7 transition metal with chemical properties analogous to technetium, was employed as a non-isotopic surrogate tracer to indirectly estimate chemical recovery. Selective isolation of Tc was achieved using Eichrom TEVA resin, which exhibits a high distribution coefficient and strong selectivity for pertechnetate under acidic conditions, enabling efficient separation and purification from interfering matrix elements. The overall performance of the radiochemical procedure was systematically validated through spike experiments and application to real waste samples.

Spike samples were processed through identical pretreatment, digestion, and separation steps. The experimental recovery of Re ranged from 94.2% to 97.5%, with a mean of 95.8% and a relative standard deviation of 1.5%, demonstrating stable chemical behavior and excellent reproducibility of the pretreatment process. After applying the recovery correction, the quantified Tc-99 analytical results showed good agreement with the reference values, yielding 104.9-109.2% of the expected activities (mean 106.9%, RSD 1.5%). These results confirm high analytical accuracy and precision and indicate that Re effectively mimics the chemical behavior of pertechnetate during separation.

To further evaluate practical applicability, the developed method was applied to real decommissioning waste matrices, including concrete, SUS-304 stainless steel, and Inconel samples. Although Tc separation and quantification were successfully achieved, the measured activities were systematically underestimated by approximately 20–40% compared with the reference values. This negative bias is presumed to result from incomplete dissolution of heterogeneous solid matrices, matrix interferences, or residual Tc retention during chemical processing. These findings highlight the need for further optimization of digestion and pretreatment conditions when analyzing complex decommissioning materials.

Overall, the combination of Re-based surrogate recovery correction and TEVA resin separation provides a practical, robust, and reproducible analytical strategy for Tc-99 determination without reliance on short-lived isotopic tracers. The proposed method offers reliable quantification for both controlled laboratory standards and real-world radioactive waste samples and is expected to be widely applicable to routine monitoring and decommissioning waste assessment.

ACKNOWLEDGMENTS
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Climate, Energy & Environment(MCEE) of the Republic of Korea (No. RS-2023-00239183).

Speaker: BOGIL KIM

5:18 PM A study on removal of Cs from simulated seawater by ammonium phosphomolybdate (AMP) and natural zeolite alginates

In this study, ammonium phosphomolybdate (AMP) and natural zeolite microcapsules with an excellent sorption property for Cs were encapsulated in the biopolymer matrices (sodium alginate, NaALG) to look into the removal of Cs in the simulated seawater induced by an emergency accident of nuclear power facilities. The results revealed that a relatively higher distribution coefficient (Kd) of Cs for
AMP–alginates than natural zeolite. The adsorption capacity of different alginates in AMP was (0.102±0.001 m mol/g) higher than natural zeolite (0.078±0.001 m mol/g). According to column test, both AMP and natural zeolite alginates showed an excellent removal efficiency ( ≥ 90%) under a relatively higher flow rate ( > 45mL/min) in simulated seawater. According different surface, elemental and mineral experiments, there is no obvious difference in both AMP and natural zeolite alginates after adsorption of Cs by N2-BET surface area , X-ray Fluorescence (XRF), and X-ray Diffraction (XRD) analysis.

Speakers: Dr CHUAN-PIN LEE (Center for Energy and Environmental Research , National Tsing Hua University 300044(NTHU) Taiwan), Mr Yu-Hung Wang (Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300044, Taiwan (R.O.C)), Ms Liang-Yu Tao (Radiation Monitoring Center, Nuclear Safety Commission, Kaohsiung City 833172, Taiwan (R.O.C))

5:21 PM Ti-based core-shell shaping for Ac-225/Bi-213 separation

Cancer remains one of the leading causes of death worldwide, requiring innovative methods for its treatment such as targeted alpha therapy with Bi-213-based radiopharmaceuticals. Alpha radiation is especially promising as it enables maximum destruction of malignant cells while minimizing cytotoxicity on the surrounding healthy tissue. However, current challenges in separating the radioactive Bi-213 from the mother Ac-225 isotope prevent more widespread use in a clinical environment despite the promising results. Therefore, the development of an innovative new sorbent material with a long operational lifetime (~10 days), shaped to enable the required fast (de)-sorption kinetics (≥80% Bi-213 yield in 2 mL eluate), is needed. Moreover, the harsh separation conditions—exposure to highly acidic media (< pH 3) and high radiation doses (~10 MGy absorbance over 2 weeks)—limit the number of materials qualified for this application. Although inorganic support materials show potential, they need to be shaped to an appropriate macroscopic architecture which allows sufficiently fast (de)-sorption kinetics. The aim of this work is to develop a micron-sized core-shell type stationary phase consisting of a Ti-support with tuned surface porosity that promote the desired fast (de)-sorption kinetics, while adjusting chemical composition and structural features to provide optimal separation performance (selectivity and yield) in combination with radiation and acid stability.

Speaker: Thomas Staes (SCK CEN)

5:24 PM Development of radiation-stable and selective sorbent materials for direct 213Bi generators

Developing effective cancer treatment strategies remains a global challenge. Targeted alpha therapy (TAT) with Bi-213 as alpha emitter has emerged as a promising approach, offering cytotoxic effects on cancer cells while minimizing damage to healthy tissue. However, Bi-213 production is limited due to the lack of sorbent materials that are both selective and resistant to acidic environments and radiation, hindering efficient separation of Bi-213 from its parent Ac-225. Given the urgent need for novel Ac-225/Bi-213 separation systems, known as Bi-213 generators, the potential of phosphate-modified titania as a sorbent material for their development is investigated. The synthesized materials were characterized by various techniques, such as zeta potential analysis, DRIFT spectroscopy, argon sorption and P NMR, while batch sorption tests were conducted with lanthanum (non-radioactive surrogate for Ac-225) and bismuth to evaluate the sorption behaviour. Furthermore, the acidic and radiolytic stability of the phosphate-modified titania was evaluated by exposure to nitric acid and by irradiation with a Co-60 gamma source, respectively. The results showed that titania exhibited a high and selective bismuth uptake at low pH, regardless of the modification degree. Lanthanum removal, on the other hand, only reached similar levels to bismuth at pH ≥ 3 and with a sufficient degree of surface phosphate groups. Desorption experiments demonstrated efficient bismuth elution from the sorbent, although selectivity was limited due to substantial co-elution of lanthanum. With respect to stability, titania showed high resistance to acidic degradation, but the leaching of phosphate surface groups did diminish sorption efficiency. Finally, exposure to gamma irradiation up to 5 MGy doses revealed an excellent radiolytic stability. In conclusion, this study demonstrates that, although modified titania needs further optimization before it could be applied in direct Bi-213 generators, unmodified titania could be envisaged as a highly promising sorbent for inverse Bi-213 generators.

Speaker: Jasper Mampaey (SCK CEN)

5:27 PM Efficient removal of perrhenate (ReO4−) as a non-radioactive surrogate for pertechnetate (TcO4−) from high-chloride and nitrate media by bis-guanidinium salts

Technetium-99 (⁹⁹Tc), a troublesome radioisotope prevalent in nuclear liquid waste, poses significant environmental and human health hazards due to its long half-life, high fission yield, and high environmental mobility. The latter is particularly relevant because, in addition to a fission product in nuclear power plants, the isotope ^99mTc is used in radiodiagnostics and is continuously released into the environment in trace amounts. Highly water-soluble pertechnetate (TcO₄^–) in particular is the dominant species in oxygenated groundwater and thus poses an increased risk. In this work, perrhenate (ReO₄⁻) is used as a non-radioactive surrogate for TcO₄⁻ to evaluate sequestration performance under high chloride/nitrate matrix conditions. Hence, ⁹⁹Tc removal is the subject of extensive research, and various methods have been investigated, including graphene-based materials, layered double hydroxides (LDHs),benzene-aminoguanidinium Ligands, and functionalized metal–organic frameworks (MOFs).In this context perrhenate is particularly interesting as it can serve as a non-radioactive surrogate for pertechnetate.
Here we report on the synthesis of oligo(ethylene glycol) guanidinium salts and their capability for the selective removal of oxoanions form an aqueous environment by precipitation. The exceptionally low water solubility over a wide pH range was exploited to achieve perrhenate removal rates of up to 98%, even in the presence of a high excess of chloride and nitrate ions. Under basic conditions, the synthesized bis-guanidinium salts can be regenerated and used for renewed precipitation of oxoanions. X-ray structural analyses were performed on suitable single crystals and used to derive structure-activity relationship.

Speaker: Mr Lapislazuli Chekrain Valappil

5:30 PM Automation of AMP Pre-treatment for 60 L Seawater Cs-137 Analysis: Comparative Evaluation of Recovery Yield and Reduction of Hands-on Time

Ammonium molybdophosphate (AMP) pre-treatment is widely used for radiocesium (Cs-137) analysis in large-volume seawater samples; however, conventional manual procedures involve substantial operational challenges, including handling of bulk samples (e.g., 60 L), strong-acid dosing for pH adjustment, and potential variability in recovery during settling, supernatant decantation, and sorbent collection. These factors raise concerns regarding operator safety, reproducibility, and throughput in routine monitoring programs.
In this study, an automated AMP pre-treatment tank system was developed, integrating closed-loop acid dosing with pH control, metered AMP addition, programmable mixing and settling sequences, automated supernatant removal, sorbent/precipitate recovery, and clean-in-place (CIP) washing. The performance of the automated system was benchmarked against the conventional manual workflow in terms of (i) cesium recovery yield (radiochemical/chemical yield), (ii) total elapsed processing time, and (iii) operator hands-on time. Manual and automated procedures were each conducted in five independent runs under comparable seawater matrix conditions.
The manual procedure yielded Cs-137 recoveries ranging from 93.29% to 98.15% (mean 96.09%), whereas the automated system achieved recoveries between 88.33% and 96.96% (mean 93.85%). Although the average recovery of the automated process was slightly lower than that of the manual method, it remained within an acceptable and stable range for large-volume seawater radiocesium analysis. In contrast, significant operational benefits were observed: the total elapsed processing time was reduced from 268.5 min (manual) to 215.8 min (automated), and operator hands-on time was markedly decreased from 97.6 min to 22.8 min.
Several automation-related issues were identified, including pH sensor response delay and signal noise, partial clogging in the sorbent recovery line, and mixing motor load alarms. Mitigation strategies such as sensor redundancy, backflush sequences for recovery lines, and torque- or current-based mixing control are proposed.
Overall, the automated AMP pre-treatment workflow demonstrates its potential to maintain comparable recovery performance while substantially improving operator safety, process standardization, and analytical throughput, making it a promising approach for routine and long-term monitoring of radiocesium in large-volume seawater samples.

ACKNOWLEDGMENTS
This work was supported by the Ministry of Oceans and Fisheries (MOF) of the Republic of Korea and the Korea Institute of Marine Science & Technology Promotion (KIMST) (No. RS-2023-00240908).

Speaker: BOGIL KIM

5:33 PM Effect of sulfation and complexation on the sorption of La, Eu and Lu on tetravalent metal oxides

Selective separation of rare-earth elements (REEs) is a central challenge in sustainable REE supply and recycling and can be useful in the radiochemical applications of these elements, for example in radiopharmaceutical chemistry and waste treatment. A hydrothermal route to synthesize tetravalent metal oxides (ZrO2, TiO2, SnO2) and their sulfated analogues was tested and their performance in separating La, Eu, and Lu in aqueous solutions was evaluated. Sulfation was achieved for zirconia and titania but not for tin oxide, as confirmed by FTIR and TGA, with high sulfate loading on ZrO2 (~24 wt%) and low loading on TiO2 (~1.5 wt%), while SnO2 remained essentially unchanged. Sulfation altered not only crystallinity, surface area and pore structure but also brought changes to sorption behavior.
Batch sorption experiments revealed that sulfated zirconia exhibits earlier onset and higher uptake than pristine ZrO2, with modest loss of selectivity. For titania, sulfation shifted preference from Eu to Lu, despite the low sulfate loading, indicating strong surface-chemical control over selectivity. Tin oxide showed identical behavior with or without sulfate treatment, consistent with unsuccessful sulfation.
The sorption of the lanthanides was manipulated using aqueous complexants. EDTA suppressed Lu uptake across all oxides while increasing La and Eu sorption on Zr-based materials at low pH, reversing the initial selectivity and markedly enhancing separations. The highest separation factor, SF(La/Lu)=95 (and SF(Eu/Lu)=32), was obtained with SnO2 in EDTA at pH ~4.7, where Lu sorption was suppressed heavily. In contrast, addition of EDTA suppressed the sorption of all lanthanides on titanium-based materials. Citrate generally increased uptake at low pH without the severe suppression seen with EDTA. On sulfated zirconia citrate inverted selectivity to favor light REEs (La>Eu>Lu), yielding moderate SFs (e.g., La/Lu≈12).
Overall, hydrothermal sulfation was shown to alter the crystal phase, pore size and surface area along with ion-exchange behavior of tetravalent metal oxides. Coupled with complexing agents, it enables pH-programmable and ligand-directed control of lanthanide selectivity, highlighting inorganic sulfated oxides, especially ZrO2 and TiO2 and EDTA assisted SnO2 as promising platforms for solid-phase separations of REEs.

Speaker: Topi Suominen (University of Helsinki)

5:36 PM Rapid chemical separation of niobium for ⁹⁴Nb activity measurement in radioactive wastes

According to the regulatory guidelines of the Nuclear Safety and Security Commission of South Korea, the activity concentrations of fourteen key radionuclides, including Nb-94, must be determined for the acceptance of radioactive waste, and analytical laboratories are required to demonstrate the capability to evaluate activity levels down to 1% of the disposal limit.

Although Nb-94 can be directly measured by gamma spectrometry without chemical separation, elevated background caused by Compton scattering from coexisting Co-60 often leads to increased minimum detectable activity (MDA), making it difficult to satisfy regulatory requirements. In addition, accurate determination of Nb-94 is essential for deriving scaling factors for heterogeneous radioactive waste such as DAW(dry active waste), sludge, spent resins, and concentrated powders.

In this study, a separation method was developed for the determination of Nb-94 radionuclide without employing anion exchange chromatography for Nb separation. A selective Fe(OH)3 precipitation step using Fe carrier at pH 4.5–5.0 was applied. Inductively coupled plasma optical emission spectrometry (ICP-OES) confirmed that more than 99.5% of Fe and Nb were retained in the precipitate, while over 85% of Co remained in the supernatant. If the gamma results do not satisfy the MDA of Nb-94, the solution is evaporated to be dried and dissolved in 0.5 M nitric acid. The insoluble residue containing Nb was dissolved using NH₄Cl/HF and directly analyzed by gamma spectrometry.

The proposed pretreatment procedure enables efficient removal of Co interference and reliable recovery of Nb-94 without dedicated chromatographic separation. As a result, the MDA of Nb-94 was successfully reduced below 1% of the disposal limit, thereby improving analytical sensitivity of Nb-94 and operational efficiency for routine radioactive waste characterization

Speakers: Dr Gyuhyeon Kim (Korasol, Co., Ltd.), Dr Kwang-Soon Choi (Korasol, Co., Ltd.)

5:39 PM Conceptual design of a tritium removal system to improve tritium removal efficiency and increase processing capacity at room temperature

Tritium is a radioactive beta emission isotope of hydrogen with a mass of 3.0 and is mainly present as tritiated water(HTO) in wastewater discharged from nuclear facilities. However, since HTO and H2O have very similar physical and chemical properties, it is very difficult to separate a trace amount of HTO mixed in a large amount of water (H2O). There is a commercialized isotope exchange and hydrogen distillation technology that can remove tritium, but this technology is a process to remove HTO from pure water quality of D2O, so it is impossible to apply to large amounts of contaminated water such as contaminated water in Fukushima. The case of Fukushima in Japan may be considered a special case, but securing the technology to remove tritium generated by the operation of nuclear facilities is absolutely necessary worldwide, and since tritium can be used as fuel for nuclear fusion, securing the technology to separate and concentrate tritium is also necessary.
However, due to technical limitations in removing tritium from contaminated water at room temperature, it is currently difficult to achieve high tritium removal efficiencies with a single technology. Our research team has already developed four technologies capable of removing tritium from contaminated water at room temperature, but their low removal efficiencies have limited their application to large volumes of contaminated water.
In this study, to overcome these technical limitations, a method to improve efficiency and increase treatment capacity by fabricating the four technologies into standardized modules and arranging multiple modules in series or parallel was designed. A single standardized module was tested under various water quality and operating conditions to ensure reproducible data. This design allows for improved efficiency through serial arrangement of the module, and increased process capacity through parallel arrangement. To achieve this, single-module experiments will focus on ensuring reproducibility rather than improving tritium removal efficiency. Standardized modules based on diverse data enable mathematical modeling to simulate and predict removal efficiency when applying multiple modules, making them useful for designing large-scale tritium removal facilities. This research is currently developing standardized modules for four technologies (HTO selective adsorption material, zeolite membrane, electrochemical module, and PEM) their tritium removal performance has been confirmed through preliminary research. The experiment involves manufacturing a simulated contaminated water containing 40,000 Bq/L of tritium. The water is then passed through MF(Micro-Filtration), UF(Ultra-Filtration), and RO(Reverse Osmosis) systems to remove all contaminants except tritium, achieving a water quality of 1 μS/cm. The water is then passed through each module to remove tritium. Future research will explore the number and arrangement of modules for each technology (1×2, 2×1, 2×2, 4×4, etc.) and observe changes in removal efficiency by passing the same concentration of tritium-contaminated water through the process. Additional research will also be conducted to improve efficiency through a combined process that considers the characteristics and operating conditions of the four modules.

Speaker: Seung-il Kim (Neosiskorea Co. Ltd.)

5:42 PM CHALMEX Solvent Extraction for Spent Fuel Recycling: Performance, Scale-Up and Safety Considerations

Closing the nuclear fuel cycle through advanced reprocessing of spent nuclear fuel is a key strategy to improve resource utilization, reduce the long-term radiotoxicity of high-level waste, and minimize the volume destined for deep geological disposal. A wide range of partitioning and separation approaches has therefore been investigated to recover fissile and fertile materials, particularly uranium, plutonium, and minor actinides. The mission is focused on recycling these nuclides as energy resources for Generation IV reactor systems, since in fast-neutron spectra, heavy nuclides exhibit more favorable fission and transmutation behavior.
Within this framework, the CHALMEX process is a solvent-extraction-based partitioning concept developed at Chalmers University of Technology. The process is designed to achieve the quantitative recovery of actinides from spent nuclear fuel using dedicated solvent extraction equipment, including mixer-settlers and centrifugal contactors. In this process, two extractants, tri-n-butyl phosphate (TBP) and 6,6’-bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzol-[1,2,4]-triazin-3-yl)-[2,2’]-bipyridine (CyMe4-BTBP), are combined and dissolved in phenyl trifluoromethyl sulfone (FS-13), enabling the direct separation and quantitative recovery of actinides.
From an industrial implementation perspective, centrifugal contactors are attractive and under investigation due to their compact design, rapid phase separation, and high mass-transfer rates. Consequently, kinetic performance and phase stability under operational conditions become crucial parameters for reliable extraction efficiency and process robustness. In parallel, nuclear criticality safety considerations remain central for the handling of fissile materials. In this case, mixer-settlers are of particular interest because the settler compartment operates without mechanical agitation and relies on gravity-driven phase disengagement, which can promote phase holdup gradients, stratification, and localized accumulation of fissile nuclides (e.g., 239-Pu). Such phenomena may create unfavorable reactivity configurations and therefore require careful evaluation in accordance with OECD/NEA and IAEA nuclear criticality safety guidance.
So far, the work is addressing two complementary aspects of the CHALMEX recycling system: kinetic and phase-behavior requirements for the process scale-up, and criticality safety considerations, relevant when mixer-settlers are selected. Together, these elements allow technology choice and operating conditions for robust actinides recovery.

Speaker: Letizia Di Matteo (Chalmers University of Technology)

5:45 PM Comparison of the effectiveness of various extraction agents for separating europium into ionic liquids

The research is focused on comparing the effectiveness of various extraction agents for separation/extraction of europium from different aqueous phases into ionic liquids.This comparison was carried out in order to describe the influence of several key parameters on the extraction efficiency (pH, extractant concentration, possible synergism between extractants) which could help to clarify the mechanism of europium extraction.

Several extractants or their combination were used and subsequently compared: TBP, TOPO, TPPO, CMPO, TODGA, and 8-HQ. Extractants were added to a conventional solvent represented by chloroform, and a perspective solvent - ionic liquid - in order to compare their extraction efficiencies in different organic media.

Ionic liquids are investigated since they are generally less volatile, toxic, and have better radiation and thermal stability compared to conventional solvents. In extraction, imidazolium based ionic liquids are one of the most studied as solvents; in this work, 1-butyl-3 methylimidazolium bis(trifluoromethylsulfonyl)imide [C4mim][NTf2] was chosen. The butyl group present in the structure is hydrophobic, which is advantageous for extraction from aqueous media, and the relatively low viscosity of [C4mim][NTf2] enables its potential use on larger, industrial, scale.

Experimental work revealed a synergistic effect between TBP and TOPO/TODGA, i.e., their extraction efficiencies improved with the addition of TBP. An obvious positive influence on extraction efficiency with the usage of the ionic liquid was confirmed for TPPO, 8-HQ, and CMPO. From all the studied organophosphorus compounds (TBP, TOPO, TPPO, CMPO) the most perspective candidate in combination with [C4mim][NTf2] appears to be CMPO, which, compared to the others, is able to efficiently extract trivalent europium to the ionic liquid across the entire studied pH range (1-10) from all the aqueous phases used.

Speaker: Daria Matějková (Czech technical University in Prague, Department of Nuclear Chemistry, Brehova 7, 115 19 Prague 1, Czech Republic)

5:48 PM ELECTROCHEMICAL BEHAVIOUR OF SELECTED METALS IN IONIC LIQUIDS FOR ELECTRODEPOSITION APPLICATIONS

Ionic liquids represent a class of compounds with unique physicochemical properties, such as negligible vapour pressure, high thermal and radiation stability, and wide electrochemical window. In combination with suitable extractants, they may serve as potential alternatives to commonly used volatile organic solvents in liquid-liquid extraction processes. Two-stage process consisting of the separation of selected metal contaminants from aqueous phase into the ionic liquids via liquid-liquid extraction, followed by the recycling of the used ionic liquids by electrodeposition was developed at the Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague in cooperation with UJV Rez. This work focuses on the electrochemical behaviour of metal species in ionic liquid-based systems and explores the potential of electrochemical techniques for their removal and recovery. Particular attention is given to electrodeposition processes as a possible approach for the separation of metal contaminants and the regeneration of ionic liquids following their use in extraction systems. Cyclic voltammetry and related electrochemical methods are considered as tools for investigating processes occurring at the electrode-electrolyte interface. Electrochemical experiments are performed under various electrochemical conditions in order to examine factors that may influence electrodeposition processes. The study aims to contribute to a better understanding of electrochemical phenomena in ionic liquid media and to assess their potential application in metal recovery and the regeneration of ionic liquid systems.

Speaker: Michal Ficel (KJCH FJFI ČVUT)

5:51 PM Static Testing Varying Ratio of Iodine or Iodomethane with Silver Zeolite – Capacity and Morphology

Radioiodine released during aqueous reprocessing must have high efficiency of capture due to environmental and safety reasons. There are various methods for capturing radioiodine such as caustic scrubbing, mercury nitrate solutions and solid sorbents. Each of these three techniques have different affinities for inorganic and organoiodines, but all radioiodine’s must be captured. Generally, organoiodines have a lower affinity with any of the techniques used compared to inorganic iodine.
Solid sorbents, such as silver zeolite, are known to have higher affinity for capturing organoiodines compared to the mercury nitrate solutions and caustic scrubbing. However, the affinity of organoiodines with solid sorbents is still lower than the affinity with inorganic iodine. Understanding the static capacity and morphological differences between inorganic iodine and organoiodines on solid sorbents can inform how to increase the organoiodine capacity. Studying how organidoines affinity differs from inorganic iodine can improve organoidoine affinity while reduce environmental impact.
In this experiment the mass ratio of analyte, either iodine or iodomethane, to silver zeolite was varied to obtain capacity curves and Scanning Electron Microscopy Energy Dispersive X-ray Spectroscopy (SEM-EDS) analyses at each ratio. The mass of analyte varied from 10% to 500% of the mass of sorbent. For each ratio, these data were obtained by placing three uncapped scintillation vials into a larger jar with a lid with ports. The scintillation vials contained a known mass of the sorbent and analyte with one vial left empty. The assembled jar containing the uncapped scintillation vials were placed in an oven at 150°C for two hours. After heating, the jar was removed and cooled, and each scintillation vial was weighed to find the mass difference. The mass difference of the sorbent vial was used to calculate the capacity at the given ratio for each analyte. The mass difference of the empty vial was used to determine any sorption of the analyte with the scintillation vial itself. Next, a few sorbent pieces were collected for SEM-EDS analysis. This process was repeated for all ratios of a given analyte and for iodine and iodomethane. The data collected show the differences in capacity and morphology between silver zeolite with inorganic iodine and organoiodine. The data collected are the first step in understanding the different interactions between these substances that can inform vital environmental questions.
Future work includes studying the stability of the sorbed analytes on the silver zeolite and performing dynamic testing.

Speaker: Rachael Roenfeldt

5:54 PM Separation of Zr in complex Ca rich matrices in nuclear decommissioning

TEVA resin was found to be inefficient for Zr separation in Ca rich matrices. Two alternative resins TBP and UTEVA resin were evaluated as replacements. For both resins it's possible to load sample
in 8-10 M HCl and retain Zr, meanwhile Ca is not retained.

TBP resin does not only retain Zr in given conditions, but it also retains Nb and Fe, which are also eluted Zr with 4 M HCl. Hence anion-exchange pretreatment of sample is required. Combination of anion-exchange pretreatment + TBP separation provided 70+ % yields for sludge, ashes and concrete, although its capacity decreased with increasing sample load.

UTEVA does not retain Fe in given conditions. Nb is retained, but it is not eluted with 4 M HCl. As a result, the anion exchange pretreatment was not strictly required, though it was applied in some cases to further stabilise the separation. The combined anion exchange + UTEVA approach produced yields above 80 % across all tested matrices. When assessing resin capacity leachate with high dissolved concrete content was used. TBP achieved only a 21 % Zr yield for 10 ml of leachate, whereas UTEVA reached an 89 % yield for 15 ml of leachate, demonstrating superior performance.

These results show that UTEVA resin is the optimal choice for Zr separation in complex, Ca rich matrix commonly encountered in nuclear decommissioning samples.

Speaker: Karel Burian (UJV Řež, a.s.)

5:57 PM Selective dissolution and Separation of Lanthanides from Simulated Spent Fuel Using Betaine-Lactic Acid Deep Eutectic Solvent

Deep eutectic solvents (DESs), a novel class of environmentally benign solvents, have emerged as a key focus in the field of metal ion separation. DESs are eutectic mixtures formed by combining hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) in specific molar ratios, resulting in melting points significantly lower than those of the individual components and often rendering them liquid at room temperature. DESs have exhibited excellent dissolution capacity for certain metal oxides. Lanthanide elements account for approximately 35–40% of the total mass of fission products in spent nuclear fuel (SNF). As strong neutron absorbers (neutron poisons), they impair reactor operational efficiency; meanwhile, they possess considerable economic value due to their recoverability and recyclability. Nevertheless, separating and recovering rare earth elements from spent nuclear fuel presents significant challenges due to the similar chemical properties between lanthanides and actinides.
This study employed a deep eutectic solvent (DES) composed of betaine (BET) and lactic acid (LA) to investigate its separation behavior toward lanthanides in simulated spent nuclear fuel. Key parameters influencing dissolution—including water content in the DES, temperature, solid-to-liquid ratio, and reaction time—were systematically examined. Based on these findings, optimal conditions for the BET-LA system were established, enabling the selective dissolution and separation of Ln2O3 from the simulated fuel. Under the optimized conditions, the removal efficiency of Ln2O3 (La, Nd, Eu, and Gd) reached 90 %, while the dissolution of UO2 was merely 1.5 %. This remarkable selectivity enables the effective recovery of UO₂ powder with an overall yield of approximately 98%. Meanwhile, the separation mechanism was elucidated with the help of UV–Vis, FT-IR and mass spectrometry. These results demonstrate the potential feasibility of separating Ln2O3 from spent nuclear fuel via selective dissolution. It should be noted that this study was conducted using simulated spent nuclear fuel, which inherently imposes certain limitations on the generalizability of its findings. Nevertheless, the BET-LA DES offers advantages including low production cost, biodegradability, and low toxicity, suggesting its potential applicability for the separation of Ln in nuclear fuel reprocessing. Beyond nuclear applications, this DES also holds significant potential for the sustainable recovery of rare earth elements from other secondary resources.

Speaker: Fangli Fan

6:00 PM Removal of Iron and Aluminium from Reactor Storage Pool Water Using Polymer Membranes

The Research Centre Řež operates the LVR-15 light-water research reactor with an operational thermal output of 10 MW. The reactor is used for experimental purposes and for the production of radioisotopes for medical and industrial applications. The system includes a storage pool B used for long-term storage of materials used in irradiation (e.g., probes or irradiation channels). In most cases, this material is made of aluminum or steel.
Water in storage pool B of the LVR 15 research reactor shows persistently elevated concentrations of iron and aluminium, caused by gradual corrosion of metallic materials stored in the basin. The aim of this work was to experimentally evaluate the potential for reducing these concentrations using pressure driven membrane filtration with polymer membranes (MCE, NYL) of various pore sizes ranging from 3.0 to 0.22 µm. Filtration was tested at three pH values (acidic, neutral, alkaline) and under conditions of artificially increased iron concentration to verify the formation of colloidal particles and their potential for more efficient separation.
The results demonstrated that filtration efficiency strongly depends on pH and on the chemical forms in which Fe and Al occur in solution. At the natural pH (~5.8), both iron and aluminium were effectively removed at pore sizes of 0.8–1.2 µm due to the presence of insoluble hydroxide species. In contrast, under acidic conditions (~2.7), both elements were present predominantly in soluble ionic forms and were therefore not retained by any of the tested membranes. In alkaline conditions (~11.3), iron removal was highly efficient, with concentrations falling nearly to zero when using 0.22 µm nylon membranes. Aluminium, however, remained primarily in stable soluble complexes under the same conditions, and even the smallest pores did not achieve significant retention. After the addition of 5 mg/L of iron, aluminium removal improved, likely due to co coagulation, while iron removal remained limited.
The study shows that membrane filtration can be an effective method for reducing iron concentrations in water from storage pool B, particularly under alkaline conditions. The efficiency for aluminium is significantly restricted by its speciation and the formation of stable soluble complexes. A combination of membrane filtration with controlled pH adjustment or coagulation processes appears to be a promising direction for further optimisation.

Speaker: Kryštof Konečný (CTU in Prague, CVR Rez, Czech Republic)

6:03 PM Separation and Recovery of the Platinum Group Metals Pd, Ru and Rh by adsorption on hexacyanoferrates structures for spent nuclear fuel reprocessing

Palladium (Pd), ruthenium (Ru), and rhodium (Rh) are platinum group metals (PGM) present in spent nuclear fuel. These elements play important and irreplaceable roles in many industrial applications in modern society, including catalysis, electronics, and pharmaceuticals. However, their extremely low abundance in the Earth’s crust, combined with their high demand and cost, has intensified the search for new sources of these elements [1]. In addition, the European Critical Raw Materials initiative identifies PGMs as essential materials with a high supply risk and strategic importance for the economy and key technologies [2]. Spent nuclear fuel may therefore represent a rich, non-conventional source of these critical elements, in which they are formed as fission products. It has been estimated that 2.4 tonnes of Pd, 3.7 tonnes of Ru, and 0.7 tonnes of Rh could be recovered from the nuclear fuel spent annually in France. Thus, significant amounts of PGMs can potentially be recovered from spent nuclear fuel in comparison with the current global production, particularly in the case of Ru [3].
In this work, hexacyanoferrate structures, namely Cu2[Fe(CN)6] and Co2[Fe(CN)6], were prepared and applied for the recovery of Pd, Ru, and Rh. The synthesized materials were characterized by X-ray diffraction and thermogravimetric analysis. Mass distribution coefficients (Kd) were determined over a wide range of nitric acid concentrations (0.01, 1, 3.2, 5, and 7 mol L-1) using the batch equilibrium method at room temperature. The effects of key adsorption parameters, including adsorbent dosage and contact time, were investigated. Adsorption isotherms and kinetic models were also evaluated. Excellent Pd adsorption performance was observed for both materials, particularly for Cu2[Fe(CN)6], which achieved nearly 100% Pd removal from 3.2 mol L-1HNO3 even at the lowest tested adsorbent mass, while the adsorption of Ru and Rh remained low. Furthermore, Pd uptake was rapid and followed a pseudo-second-order kinetic model. Both hexacyanoferrate structures showed good stability in 3.2 mol L-1HNO3, with no detectable release of Cu or Co during the tested period of 14 days.

References:
[1] H. Weng, Y. Wang, F. Li, Y. Muroya, S. Yamsahati, and S. Cheng, “Recovery of platinum group metal resources from high-level radioactive liquid wastes by non-contact photoreduction,” Journal of Hazardous Materials, vol. 485, 2023, Art. no. 131852.
[2] Study on the Review of the List of Critical Raw Materials: Final Report, European Commission, 2017.
[3] S. Bourg and Ch. Poinssot, “Could spent nuclear fuel be considered as a non-conventional mine of critical raw materials?” Progress in Nuclear Energy, vol. 94, 2017, pp. 222–228.
Acknowledgement: We gratefully acknowledge the EU and Czech MEYS funded project CROP (CZ.02.01.01/00/22_011/0008569) and the HORIZON-EURATOM-2021-funded FREDMANS project (GA No. 101060800) for supporting this research.

Speaker: Dr Iga Zuba (Czech Technical Univeristy, Institute of Nuclear Chemistry and Technology)

6:06 PM Remarkable Separation of Trace Amount Plutonium Using a Hy-drophilic Multiamide Ligand: Synthesis, Extraction, Spectroscopic, Crystal Structure and Density Functional Theory Studies

The removal of trace plutonium (Pu) from uranium products and organic wastes during spent nuclear fuel reprocessing remains a critical challenge, resulting in excessive plutonium content in uranium products and waste organic liquid. Currently, most organic ligands with selective separation functions are lipophilic, while research on water-soluble highly selective ligands is relatively scarce, and there are also few reports on the single crystal of these ligands coordination with plutonium. Herein, a hydrophilic multiamide ligand, N,N,N',N'',N''-hexaethyl-nitrilotriacetamide (NTAamideC2), was synthesized and evaluated for its Pu(IV) back-extraction efficiency under harsh conditions. Systematic experiments revealed that NTAamideC2 achieved >99% Pu(IV) back-extraction rate within 15 minutes across a wide nitric acid concentration range (0–5 M), even with elevated dibutyl phos-phate (DBP ≤20,000 ppm). Remarkably, the separation factor (SFPu/U) reached 767 at 1.5 M HNO3, demonstrating excep-tional selectivity over uranium(VI). Spectrophotometric titration and DFT calculations confirmed the formation of 1:1 and 1:2 Pu(IV)-NTAamideC2 complexes, with log β values of 7.42 ± 0.01 and 13.23 ± 0.02, respectively. Single-crystal X-ray diffrac-tion analysis of {Pu2(H2O)2(NTAamideC2)42(NO3)(ClO4)7} revealed a nine-coordinated PuO7N2 geometry, where two NTAamideC2 molecules bind via six O and two N atoms. Compared to conventional agents (AHA/HSC), NTAamideC2 ex-hibited superior acid tolerance and selectivity, aligning with the CHON principle for sustainable nuclear waste management. This work provides a robust strategy for Pu(IV) removal in uranium purification cycles and advances fundamental insights into Pu co-ordination chemistry, offering significant potential for industrial nuclear fuel reprocessing.

Speaker: Tiansheng He (China Institute of Atomic Energy)

6:09 PM TK300 - A new calixarene-based resin for the separation of Cs

TrisKem International, ZAC de l’Eperon – 3 rue des Champs Geons, 35170-Bruz, FRANCE

Isotopes of Cs ($^{134}$Cs, $^{135}$Cs, $^{137}$Cs) are important markers of artificial contamination. A fast and selective separation of Cs and interfering elements is important for precise analysis using low-level ICP-MS.

A new resin (TK300) based on a calixarene and a fluorinated alcohol was developed for the separation of Cs from environmental and decommissioning samples. The resin is highly hydrophobic, accordingly 20% ethanol is used for its preconditioning.

The TK300 Resin shows the highest Dw values for Cs in 2M HNO$_3$. Loading of Cs is performed from 2 M HNO$_3$. Rinsing is performed with 2M HNO$_3$. Cs is then eluted with water. These conditions can be used for trace and elevated amounts of Cs. In case of elevated amount, 0.1-0.2 mg of Cs carrier can be used per 2 mL cartridge (the theoretical capacity is 1.45 mg Cs/g resin). In this case, 10 mL of water is enough for the elution of Cs.

Loading in more diluted acidic medium (0.1 M - 2 M HNO$_3$) is also possible for both trace and elevated amounts of Cs, but the concentrations higher than 0.5 M HNO$_3$ are preferable because of low retention of Tc in 0.1 M HNO$_3$.

Under these conditions (0.5-2M HNO$_3$), Cs was separated from most of the interfering elements, in particular Ba, which is important for ICP-MS analysis of $^{137}$Cs.

Speaker: Illarion Dovhyi (Triskem International)

6:12 PM New developments in Triskem: Preparation of extraction chromatographic separation materials based on new non-resin supports

Triskem develops extraction chromatographic resins specific for radionuclides and/or group of radionuclides that are used in different fields such as environmental monitoring, decommissioning, nuclear medicine, and more. Depending on the application, the resin format is not always the most efficient option. This is why in the last years Triskem has initiated the development of new formats such as selective discs/filtering membranes and impregnated Thin Layer Chromatography supports. TK100 Discs are used in DGT devices for the accurate quantification of trace-level (μg L–1) Sr and Pb concentrations and isotope ratios [δSRM 987(87Sr/86Sr) and δSRM 981(207Pb/206Pb)] in labile, bioavailable element fractions in soils (1,2). TK201 Discs have been used for the preconcentration of Tc-99 from hospital waster waters before purification and quantification by ICP-MS (3). In the same format, TK-GA Discs have been developed to trap actinides from water samples during filtration and thus allowing subsequent alpha spectrometry analysis (4).
TLC supports functionalized via impregnation with selective extractants is another field of development to provide mostly nuclear medicine with fast quality control regarding labelling yields and radionuclidic impurity determination. DGA Sheets have been developed by Kozempel et al. at CTUP for the determination of radionuclidic impurities e.g. in Ra-223, Ac-225 or Pb-212 solution for use in labelling. They further have been used to quantify Ra-Macropa labelling yields. CU Sheets have been developed to facilitate the analysis of Cu radiolabelled peptides.
Further, the development of other selective Discs/filtering membranes and ITLC supports currently being developed are presented here.
Key words: impregnated discs, iTLC, TK100 discs, TK-GA discs, DGA Sheets, CU Sheets.

References
(1) S. Wagner, J. Santner, J. Irrgeher et al. Selective Diffusive Gradients in Thin Films (DGT) for the Simultaneous Assessment of Labile Sr and Pb Concentrations and Isotope Ratios in Soils. Anal Chem, 2022, 94, 16, 6338-6346
https://doi.org/10.1021/acs.analchem.2c00546
(2) S. Wagner, J. Santner, M; Puschenreiter, et al. Prediction of Radiogenic Sr and Pb Isotope Signatures in Plants using Diffusive Gradients in Thin Films. Analytical and Bioanalytical Chemistry, 2026, 418, 1541–1555
https://doi.org/10.1007/s00216-026-06315-6
(3) M. Horstmann , C. Derrick Quarles Jr , S. Happel et al. : Quantification of technetium-99 in wastewater by means of automated on-line extraction chromatography – anion-exchange chromatography – inductively coupled plasma-mass spectrometry. J. Anal. At. Spectrom., 2024, 39, 2774-2782, https://doi.org/10.1039/D4JA00270A
(4) C. Bailly et al. Selective impregnated Membrane Filters for Direct Alpha Spectrometric Analysis of Actinides; Applied Radiation and Isotopes, in preparation

Speaker: Dr Aude Bombard (Triskem)

6:15 PM Sulfur-containing extraction systems for Rh, Ru and Pd in nitrate media relevant to spent nuclear fuel reprocessing

Platinum group metals (PGMs) are listed among critical raw materials essential for economic development, everyday life, and industrial applications as defined by the European Commission [1]. Spent nuclear fuel represents a promising secondary resource, as PGMs are present in higher concentrations than in primary ores [2]. Their recovery could also contribute to reducing the overall cost of spent nuclear fuel reprocessing.

This study therefore investigates the possibility of separating PGMs from nitric acid media by liquid-liquid extraction, applicable in spent nuclear fuel reprocessing. The aqueous phase contained nitric acid (3 mol/L) and nitrates of rhodium, ruthenium, and palladium at concentrations representative of those expected in spent nuclear fuel raffinate. Initial experiments were focused on the extraction of PGMs into pure solvents (kerosene, benzene, chloroform, n-octanol, bromobenzene, and selected ionic liquids) to provide a baseline for subsequent experiments. The effect of solvent pre-saturation with the aqueous phase on PGMs extraction was also evaluated. The essential part of the study was focused on PGMs extraction using primarily extractant N′-benzoyl-N,N-diethyl-thiourea, with particular emphasis on the effect of various parameters e.g. extractant concentration, nitric acid concentration, nitrite presence, and mutual-phase contact time. In these experiments, ruthenium showed partial extraction, while rhodium was not extracted. Palladium was quantitatively extracted even at low extractant concentrations. Additionally, palladium extraction increased with decreasing nitric acid concentration. No positive effect of nitrite presence on PGMs extraction was observed.

Speaker: Ondřej Holas

7:30 PM → 9:00 PM Socials: Beer Party

Tue, May 12

8:30 AM → 10:00 AM Separation & Speciation: SEP2

Conveners: Kenneth Czerwinski (University of Nevada, Las Vegas), Nora Vajda (RadAnal Ltd.)

8:30 AM The Role of Group Actinide Separation Process (GrASP) for a Sustainable Fuel Cycle

As energy demands increase due to technological advancements like data centers and AI-technology, discussion surrounding the reprocessing of used nuclear fuel has been escalating. The US is at risk of undermining its status as a world leader in nuclear by having no clear plan to deal with the nearly 100,000 MTHM of used nuclear fuel currently in interim storage. An expansion of the well-known Actinide Lanthanide SEParation (ALSEP) in the form of a two-cycle, single-solvent flowsheet termed Group Actinide Separation Process (GrASP) is a modern answer to UNF reprocessing in the US.

The solvent in GrASP is comprised of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and N,N,N′,N′-tetra(2- ethylhexyl)diglycolamide (T2EHDGA). To start the first cycle, the UNF feed solution is treated with the common carboxylic acid trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA), suppressing zirconium and palladium extraction. Acetohydroxamic acid (AHA) and hydrogen peroxide are used to reduce neptunium to Np(IV), ensuring its extraction with uranium and plutonium. Molybdenum and technetium are scrubbed after the initial extraction, leaving only U, Pu, and Np in the loaded solvent. A group actinide strip solution strips >99% of Pu and Np, with a tunable fraction of U. The remaining U is then stripped with phosphoric acid or a carbonate solution.
The second cycle of GrASP closely resembles ALSEP. The initial raffinate is contacted with the stripped solvent and has been demonstrated to perform as well as fresh solvent based on Eu/Am separation factors. Inductively coupled plasma mass spectroscopy and optical emission spectroscopy (ICP-MS and OES) were used to determine the behavior of the stable fission products during extraction and scrub steps. Liquid scintillation counting (LSC) was used to obtain D-ratios for the major actinides.

GrASP provides several advantages over traditional reprocessing schemes. The efficient management of Np, Tc, and the trivalent actinides has historically remained elusive, but GrASP effectively handles theses problematic elements. Additionally, the lack of an isolated Pu stream contributes to proliferation resistance. Finally, the single-solvent nature increases safety by reducing the complexity of the process and may reduce build costs by reducing necessary tank storage for reprocessing plants.

Speaker: Quinn Summerfield

9:00 AM Pyrochemical Group Separation of Lanthanides from Spent Nuclear Fuel Powder

Accelerator-Driven Advanced Nuclear Energy System (ADANES) is currently under development and construction at the Institute of Modern Physics, Chinese Academy of Sciences. The ADANES design aims to burn spent nuclear fuel (SNF) and utilize the uranium content for electricity generation. To achieve high-efficiency uranium utilization, fast neutron poisons must be removed from the SNF. Lanthanides, as one of the main groups of fast neutron poisons, significantly reduce uranium utilization efficiency. Therefore, lanthanides must be separated from the SNF prior to its introduction into the ADANES burner.
A pyrochemical process has been developed and tested for the group separation of lanthanides from SNF. In this method, a chlorinating agent is introduced into a mixture containing UO₂, Sm₂O₃, Nd₂O₃, Eu₂O₃, Gd₂O₃, among others. The lanthanides are first selectively converted into chlorides at 360°C and subsequently evaporated from UO₂ at 1100°C under an argon atmosphere. A removal efficiency exceeding 50% has been demonstrated. This pyrochemical process shows promising potential for the rapid and effective group separation of lanthanides from spent nuclear fuel.

Speaker: Mu Lin (Institute of Modern Physics, Chinese Academy of Sciences)

9:20 AM N,N-Dibutyl Octanamide (DBOA)–Based Solvent Systems for Actinide Co-Extraction: A TBP Alternative for the CHALMEX Process

Division of Nuclear Chemistry and Industrial Materials Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden

Closing the nuclear fuel cycle requires separation processes that recover actinides efficiently while minimizing the radiotoxicity and heat load of the waste requiring long-term storage. In this context, advanced reprocessing strategies increasingly target the recycling of minor actinides (MAs: Am, Cm, Np).(1) CHALMEX is an advanced aqueous solvent-extraction concept derived from the second cycle of the GANEX (Grouped ActiNide Extraction) process, with the goal of recovering all actinides in a grouped manner. (2) Accordingly, CHALMEX focuses on one-stage co-extraction of U, Pu and minor actinides from spent nuclear fuel raffinates.
This study compares the traditional extractant tri-n-butyl phosphate (TBP) with the CHON-compliant monoamide, N,N-dibutyl octanamide (DBOA) formulated in the fluorinated diluent FS-13. In both cases, CyMe₄-BTBP was to enable grouped extraction across the different actinide oxidation states relevant to spent nuclear fuel. Batch solvent-extraction experiments were performed using equal volumes of organic and aqueous phases (1.5 mL each). The aqueous feed was an inactive simulated PUREX raffinate prepared in 3 M HNO₃, containing representative fission and corrosion products (lanthanides and transition metals) and spiked with trace concentrations of U(VI), Np(V), Pu(IV), Am(III), and Cm(III). To suppress co-extraction of selected fission products, Bimet and D-mannitol were added as masking agents.
The performance was first investigated in batch tests, together with fission- and corrosion-product behavior and solvent stability under process-relevant aging. Radiolytic stability was assessed by γ-irradiation of the organic phases up to 300 kGy, followed by re-evaluation of extraction performance, which allowed any changes to be correlated with solvent aging and degradation. Under identical conditions, the DBOA-based solvent extracted U(VI) and Pu(IV) efficiently, in line with the expected formation of neutral nitrate adducts such as UO₂(NO₃)₂·2DBOA and Pu(NO₃)₄·2DBOA. Notably, Pu(IV) exhibited a higher distribution into the organic phase compared with the TBP-based system. Based on these batch screening results, actinide recovery was then evaluated in a representative flowsheet sequence comprising extraction, scrubbing with 3.5 M NaNO₃ + 0.5 M HNO₃, and stripping with 0.5 M glycolic acid at pH 4. Overall, the DBOA solvent achieved effective grouped actinide co-extraction and subsequent back-extraction under the selected conditions while retaining acceptable selectivity against fission products.

Reference:
1. OECD Nuclear Energy Agency (NEA). Strategies and Considerations for the Back End of the Fuel Cycle. OECD Publishing (2021).
2. Authen, Thea Lyseid, et al. Solvent Extraction and Ion Exchange 40.3 (2022): 189–202.

Speaker: Esraa Darwish (Chalmers University of Technology)

9:40 AM Novel Highly Selective Bistriazolyl-Phenanthroline and Phenanthroline-Dicarboxamide Ligands for i-SANEX Separations

We report two new hydrophilic phenanthroline-based ligands developed for the separation of actinides from lanthanides in the i-SANEX process: one of bistriazolyl-phenanthroline (BTrzPhen) type incorporating sulfonated hydrophilic groups, and another of phenanthroline-dicarboxamide type named AE-DAPhen. Both ligands exhibit high solubility in aqueous nitric acid solutions. Among them, DSC-BTrzPhen, achieved an excellent separation factor (SF_Eu/Am) exceeding 440. This represents the highest recorded value for any BTrzPhen ligand. Another ligand, AE-DAPhen, demonstrated a maximum separation factor (SF_Eu/Am) of 325. Furthermore, solvent extraction tests conducted with Cm(III) indicated SF_Eu/Cm being 50 for AE-DAPhen, yielding a relative separation factor (SF_Cm/Am) of 7.4, although recent results obtained by a different approach are placing that value at around 4.5-5, which is still an excellent result. Coordination studies, fluorescence spectroscopy, and theoretical and computational investigations have further revealed the characteristics of these two ligands and helped elucidate their possible mechanisms.

Speaker: Pavle Mocilac (Lanzhou University)

8:30 AM → 10:00 AM Nuclear Analytical Methods: NAM 1

Conveners: Elisabete De Nadai Fernandes (Nuclear Energy Center for Agriculture, University of São Paulo), Xiaolin Hou (Lanzhou University)

8:30 AM The role of neutron activation analysis in the detection of errors in reference materials

One of the most appreciated advantages of neutron activation analysis (NAA), being a primary method of measurement, is its potential for accuracy and the possibility to provide a complete uncertainty budget of the results. For this reason, NAA has an indispensable role in certification of element mass fractions in reference materials (RMs), especially at very low levels. Not less important role NAA also plays in the detection of erroneously certified values, which occasionally occur even in RMs of well recognized producers. Well known examples of mass fraction values corrected on the basis of NAA results involve the As mass fraction in NIST SRM-1571 Orchard Leaves in the 1970’s, the Cu and Mn mass fractions in IAEA A-11 Milk Powder in the 1980’s and the Mn and V mass fractions in NIST SRM 1648 Urban Particulate in the 1990’s. We have also observed a gradual, time-dependent increase in the Na mass fraction in NIST SRM 1515 Apple Leaves and NIST SRM 1547 Peach Leaves, which has almost doubled to date compared to the original value certified in 1991.
Now we report the detection of discrepancies between the Cr and V certified mass fractions, the K indicative mass fraction in CRM AN-OK01 Sewage Sludge (Analytika, s.r.o., Czech Republic) and our NAA results. The proof of accuracy of our results can be inferred from the agreement of our values for several RMs with matrices and element levels similar to CRM AN-OK01.
Known or possible reasons for the discrepancies detected are discussed, as well as the importance of the use of NAA in the certification process of element mass fractions in RMs. Nowadays, we unfortunately encounter a decreasing availability of NAA laboratories capable of serving for this task.

Speaker: Prof. Jan Kučera (Nuclear Physics Institute of the Czech Academy of Sciences)

9:00 AM Updating the spectroscopy database for high-resolution Prompt Gamma Activation Analysis

One of the main difficulties in quantitative analysis using the PGAA technique is the large number of peaks detected in the prompt-gamma spectra. It needs a comprehensive database containing the energy and cross section information for all the elements enabling the identification of the different elements. The IAEA made available the libraries developed in Budapest in the early 2000s and it have been used for several other purposes than just chemical analysis. During the analytical work both in Budapest and in Garching, the library was improved and updated, thus the evaluation of the complicated spectra became much more reliable enabling a complete element analysis from the difficult-to-measure light elements to the trace elements. The improved database will be published in the near future to be used in PGAA labs and in any other applications where precise (n,gamma) data are required. The talk presents advantages of the high-resolution PGAA and the developments in the database project.

Speaker: Zsolt Révay (Technische Universität München - FRM II)

9:20 AM Latest Developments in Application of Machine Learning Algorithms in Analysis of PGAA Spectra

Analysis of spectra in PGAA is a well-developed method with, in principle, straightforward data treatment. However, the large number of emitted gamma rays, interference of the gamma rays from different elements and the specific relative ratio of elements in the sample can make the process of analysis time consuming. Even with experts analyzing the data, the analysis in some cases can get complex and it becomes difficult to achieve the necessary quality in identifying and quantifying the elements present in the target material in a reasonable time.

Prospects of automation of PGAA analysis with Machine Learning algorithms is currently being investigated in the framework of the EvalSpek-ML project funded by the BMBF, Germany. This project encompasses the usage of ML methods for spectral analysis in various fields of physics, such as astrophysics and neutron scattering. The overview of the project will be presented, but the primary focus will be on the PGAA.

Preliminary work on applying ML algorithms to the PGAA data revealed several weak points. One of the problems was the number of available spectra. While artificial augmentation of the spectra is possible to a degree, the number of the spectra available at the PGAA facilities is usually relatively small compared to the numbers usually required by the algorithms to ensure the successful training. The second issue was that, as a user facility, spectra measured at the PGAA station of FRM II are primarily measured for specific research application, so the availability of spectra for different elements is unevenly distributed, which can cause problems in the training of the algorithms.

The first way to overcome this issue is to focus on the spectra with a small number of elements present and with relatively high number of spectra available in order to more precisely test the capabilities of various networks. In this work, the spectra containing primarily Fe and Cl were chosen, and the results of the research on these spectra will be presented. The second way to improve the training of ML algorithms is to use the simulations. PGAA spectra are quite complex to simulate, so some sort of tradeoff is always necessary when choosing the complexity level of the simulations. The simulations and their application within various ML algorithms will be presented as well. While additional work is required, preliminary results show that the analysis of the PGAA spectra can be supported with the use of ML algorithms.

Speaker: David Knežević (Technische Universität München - FRM II)

9:40 AM INAA of sands from the Northwest China deserts, supposed source materials for Australasian tektites

Neutron activation analysis in its instrumental mode (INAA) is a powerful tool for geochemical analysis, allowing the determination of most major and numerous trace elements. Thanks to its minimal demands for sample preparation and treatment, INAA becomes handy namely in the analysis of extensive sample series, which has been the case of INAA of 80 samples of Lingtai loess and 230 sand samples from drill cores in the Badain Jaran Desert (BJD) and Tengger Desert (TD), Northwest China. These materials have been studied as potential source materials for Australasian tektites (AAT).
AAT were created by a meteoritic impact 0.8 Ma ago, and despite forming the largest strewn field of all terrestrial tektite groups, their parent impact crater remains unknown. We have questioned its consensual location in Southeast Asia, primarily due to the geochemical incompatibility of strong chemical weathering with AAT. As an alternative, we have suggested a crater buried under giant sand dunes in BJD, supported besides the geochemical indicators also by, e.g., gravity and geomagnetic anomalies, and hydrothermal activity observed in BJD.
Our previous geochemical characterization of loess and desert sands by INAA indicated good compatibility of loess and TD samples with AAT. For the BJD suggested as an impact site, the compatibility was lower, probably due to higher carbonate and lower clay fractions in the sand. Partial melting was suggested, leading to enrichment of fine fractions in AAT and their depletion in the unmelted impact fallout. The apparent excess of Ca in the sand over the average AAT composition was explained by incomplete melting of carbonate concretions and immiscibility of carbonate (Ca- and Mg-enriched) and silicate melts, which would also explain the existence of high-Ca,Mg groups of AAT, namely in microtektites.
To test the assumed effect of grain size, selected representative BJD and TD samples from the WEDP02 and WEDP01 drill cores, respectively, were separated into fine and coarse fractions using a 125-µm sieve. The presence of both single sand grains and carbonate-cemented aggregates was observed by optical microscopy. The separated fractions were analysed both by short- and long-time (1-min and 2-h irradiations, respectively) INAA employing the LVR-15 research nuclear reactor (Research Centre Řež).
Results show that the elemental composition difference between fine and coarse fractions is quite low in TD but significant in BJD. Namely, enrichment of lanthanoids, Ti, Mn, and Mg in the fine fraction of sands dated around and before the impact was observed. This finding indirectly supports the suggested enrichment of the fine fraction in AAT and the coarse fraction in the unmelted impact fallout. The obvious excess of Ca in both fine and coarse fractions over the average AAT composition would require additional mechanism such as the suggested incomplete melting of carbonate concretions and immiscibility and separation of silicate and carbonate melts.

Speaker: Olena Bakhmachuk (1. Czech Academy of Sciences, Nuclear Physics Institute. 2. Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering)

10:00 AM → 10:30 AM Coffee Break

10:30 AM → 12:00 PM Nuclear Fuel Cycle: NFC 2

Conveners: Eva De Visser - Týnová (NRG), Václav Tyrpekl (Faculty of Science, Charles University)

10:30 AM Spark Plasma Sintering of Ceramic Fuels: New Materials and Microstructures

Spark plasma sintering (SPS) combines rapid heating, pulsed electric current, and uniaxial pressure to achieve dense ceramic bodies at markedly lower temperatures than conventional sintering, expanding the design space for microstructure, phase composition and dopant distribution.
During the last decade, at the Joint Research Centre in Karlsruhe, we exploited the versatility of SPS to synthetise a series of novel fuel materials, to address safety challenges of the nuclear fuel cycle for current and future reactors. This talk will summarise the most recent achievements, focusing on representative case studies. Examples include: (i) volatile‑element‑doped UO₂ analogues (e.g., CsI), (ii) bulk nanostructured UO₂ and ThO₂ with grain sizes < 100 nm, allowing investigation of the high‑burnup structure, (iii) high‑density UC and UN pellets, (iv) asymmetric microstructures induced by current flow with gradients in grain size and morphology. These examples show that SPS, combined with advanced powder synthesis routes, can generate previously inaccessible fuel chemistries and architectures, directly supporting improved safety analyses.

Speaker: Marco Cologna (Joint Research Centre (JRC))

11:00 AM Insights and correlation of microstructure and redox chemistry of surrogate MIMAS MOX ceramic materials

With the rising demand for more efficient energy sources the need for mixed oxide fuel (MOX) for nuclear energy production also increased, since it is a recycling product of spent UO2 fuel. MOX is a blend of UO2 and a variable amount of PuO2. Subsequently, the amount of MOX spent nuclear fuel (SNF) rises due to increased usage, in particular such with a higher burn-up history. Especially the latter entails major challenges for todays effort of final nuclear fuel disposal and repository design, as high burn-up MOX SNF embodies higher complexity, radiation/heat emission and less predictability on its long-term behaviour than other fuel types. While the blending processes and the respective microstructure evolutions of MOX are well examined, research on its chemical properties and their correlation with microstructure is rather scarce. In this work, a laboratory-scaled synthesis method has been developed to synthesize simplified model system materials based on Ce-based surrogate material to examine MOX fresh and spent ceramics. The used blending procedure is based on the industrially established micronized master blend (MIMAS) method, which is known to yield heterogeneous ceramic materials. Heterogeneous MOX types are focussed in this work since these present greater challanges when occuring as SNF than initially homogeneous MOX fuel types. Emphasis has been placed on the microstructural impact of the choice of UO2 precursor and how the microstructure subsequently affects the chemistry of Ce and U. The samples were analysed microstructurally via SEM, EDS, EPMA, in addition to PXRD analysis. Remarkebly, high-energy-resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) measurements performed on the U M4-edge and Ce L3-edge indicate considerable differences in the redox states of the MOX materials, in particular their simultaneous posession of both oxidised and reduced U and Ce respectively, likely caused by the different microstructure of the samples. These results subsequently suggest that in actual Pu based MIMAS MOX considerable diversity in redox states are found, but moreover highlight the siginificance of different synthesis routes in influencing the bulk chemistry of synthesized materials. This can impact the solubility and overall integrity of the ceramic material as phases containing U5+/Pu3+ are known to be more prone to dissolution than those with U4+/Pu4+. The results of this investigation will be discussed in relation to the geological disposal of MOX fuel, as well as the challenges involved in generating reliable Ce-based surrogate materials for MOX in addition to intricate chemistry of MOX ceramic materials.

Speaker: Egor Iwaschko (Forschungszentrum Jülich GmbH)

2026-05-12_Iwaschko_RadChem2026_Presentation.pptx

11:20 AM Improvements on the manufacturing and characterization of Cr-doped UO2 as evolutionary ATF materials

Accident-Tolerant Fuels (ATFs) are a set of technologies that aim to provide enhanced failure tolerance and safety margins under abnormal operating conditions or transients in nuclear reactors. ATFs are a wide concept, comprising improvements in both the nuclear fuel pellet (made of UO2 in most of current operating reactors) and the cladding. Focusing on the pellet, evolutionary ATFs consist in adding (i.e., doping) elements to the UO2 matrix in order to improve its properties. Among them, doping UO2 with chromium has turned out to be significantly effective for increasing grain size, which reduces fission gas release and pellet-cladding interaction, thus improving in-pile performance. In order to achieve these improved properties, the fuel fabrication process must ensure a correct incorporation of Cr within the UO2 matrix. Therefore, the aim of this work is to use novel fabrication approaches (based on co-precipitation methods) and characterization techniques to follow the state of the dopant and its stability within the UO2 matrix, both in the liquid and solid phases, over a range of Cr concentrations. From the obtained results, design and quality criteria (such as optimum Cr amount, grain size, solubility limit, etc.) are derived.

Speaker: Abel Milena Pérez (CIEMAT)

11:40 AM Experimental studies for the obtention and characterisation of a reliable analogue for Pellet-Cladding Interaction

The origin of pellet-cladding interaction (PCI), frequently occurring in spent nuclear fuel rods, lies in the simultaneous dimensional changes of the fuel pellet, which suffers irradiation- and heat-induced swelling, and the cladding, which experiences a creep-down due to the coolant overpressure. These opposed behaviours lead to the closure of the fuel-cladding gap and the eventual formation of a bonding layer, which may alter the rod stability. The lack of studies on realistic model materials for the PCI has given rise to this study. The objective is to obtain reliable analogues (morphologically and structurally realistic) for the PCI by UO2-ZrO2 interdiffusion via spark plasma sintering and, thereafter, thoroughly characterising the different formed layers. The pursued interdiffusion has been achieved for the investigated conditions, since the analysis of the UO2-ZrO2 interface by SEM/EDS and Raman spectroscopy has revealed the local creation of a mixed phase. The availability of such analogues, which make it possible to avoid handling irradiated nuclear fuel, plays a key role in the analysis of PCI alteration under different storage conditions, relevant for policy-making decisions in the nuclear sector.

Speaker: Dr Jone M. Elorrieta (CIEMAT)

10:30 AM → 12:00 PM Radionuclides Production & Application: PAR 1

Conveners: Andreas Türler, Antonia Denkova (TU Delft)

10:30 AM Ac-225 production at PanTera: from Th-229 generator produced Ac-225 towards large-scale photonuclear production

Aim:

A promising nuclide in radioligand therapy (RLT) is Actinium-225 (Ac-225), a rare alpha-emitting radionuclide that has garnered attention for its potent cytotoxicity and precision in targeting malignant cells. A growing body of preclinical and clinical evidence support its effectiveness and further increases the demand for Ac-225. However, despite its therapeutic promise, the clinical development and widespread application of Ac-225 are currently limited by production constraints, high cost, and the need for robust radiochemical handling infrastructure.

Presented here are advancements of Ac-225 production through both the thorium-229 production route and through the photon irradiation or radium-226. As both methods produce Ac-225 through Ra-225, the separation chemistry and quality control techniques are largely commutable.
The aim of developing these two production techniques simultaneously is to leverage on the currently available Th-229, while derisking and advancing the photonuclear route for a large-scale production.

A challenge in upscaling either of these methods is the worker dose, from both the final purification and dispensing step. The development of an automated purification and dispensing method is presented to ensure safe and reproducible results. The separation of Th-229, Ra-225 and Ac-225 is demonstrated on a GBq batch scale, validating column stability, the effects of radiolysis, and the elution profile of the nuclides coming off the columns.

Materials & Methods:

Chemical purity is evaluated through a high-resolution ICP-MS. Th-228, Th-229 and several tetravalent and divalent metal ions are monitored after the Th-229 separation step and on the final eluent. HPGe is used for radionuclidic identity, and for the quantification of Ac-225, Ra-225 and Ra-224.
Results: The separation of Th-229 from its daughter nuclides was performed with an AG-MP1 column at the mg scale, while the separation of Ra-225 from Ac-225 was performed using a DGA column. Bed volumes of both columns were tested and optimized for a RAC of ≥4.5 mCi/ml while achieving high radionuclidic purity of Ac-225 ≥99.8% in activity. Purity from other metallic ions is demonstrated to be 50 ng/MBq of Ac-225 or less.

Conclusion:

The results presented here not only support the GMP production of Ac-225 from the Th-229 route, but also demonstrate and derisk experimental uncertainties in larger up-scale production methods. Particularly, results on column stability against higher amounts of alpha and gamma irradiation than what is available in open literature, demonstrate a robust separation process in support of the photonuclear production method.

Speaker: Dominic Maertens (PanTera NV)

11:00 AM Production and gas-phase transport investigation of Kr and Xe radioisotopes for lead-cooled fast reactor development

Noble gases are members of group 18 in the periodic table and known for their chemical inertness. Radioisotopes of noble gases have found multiple applications, including atmospheric tracing, and medical imaging. In the development of Generation IV nuclear reactor technologies, particularly lead-cooled fast reactors (LFRs), radioisotopes of Kr and Xe are proposed as indicators for the detection and localization of nuclear fuel cladding failures. However, experimental investigations of the transport behavior of noble gases in liquid lead remain scarce. The present study therefore aims to both produce radioisotopes of Kr and Xe and investigate their potential interaction with liquid lead through the development of dedicated experimental setups.
Short-lived Kr and Xe radioisotopes (with half-lives shorter than 12 h) are provided by the existing gas-jet facility at the Swiss Spallation Neutron Source SINQ at PSI. These Kr and Xe radioisotopes are produced via the thermal-neutron-induced fission of $^{235}$U and subsequently transported to the radiochemistry laboratory using gas-jet techniques. In addition, a simple method was established for the production and gas-phase separation of $^{127}$Xe (half-life ≈ 35 d), produced via the $^{127}$I(p,n)$^{127}$Xe nuclear reaction following proton irradiation of potassium iodide targets. Radioactive Kr and Xe produced either at SINQ gas-jet or via proton irradiation were introduced into liquid lead using a dedicated experimental setup ensuring controlled atmospheric conditions. Experimental data on the transport behavior of Kr and Xe through liquid lead were collected, demonstrating the overall feasibility of using radioisotopes of noble gases as tracers for monitoring nuclear fuel cladding integrity in lead-cooled fast reactor systems.

Speaker: Haohan ZHANG (Paul Scherrer Institut (PSI))

11:20 AM Modernization in processing and dissemination of experimental cross section data in EXFOR

Radioisotope production cross sections and other nuclear reaction data measured in the world have been compiled by the Nuclear Reaction Data Centres (NRDC) for the EXFOR library under coordination by the IAEA Nuclear Data Section (IAEA NDS). IAEA's recommendation of charge-particle induced cross sections for medical isotope production fully relies on the experimental knowledge stored in the EXFOR library.

The data stored in the EXFOR library are disseminated through the EXFOR web retrieval systems maintained by the IAEA (https://nds.iaea.org/exfor/) and other centres. These systems are interactive, namely the users can receive datasets satisfying the conditions specified by them (e.g., target, projectile, product nuclide, beam energy range). The systems also allow users to plot them with newly prepared data uploaded by the users and with data stored in other databases (e.g., cross sections in evaluated nuclear data libraries).

The EXFOR format can accommodate not only the experimental data but also their descriptions (e.g., sample, detector) for proper interpretation and use of the data. The format is designed to make daily compilation and exchange between data centres easy, and use of the format is strongly supported by the EXFOR compilation community. However, it contains various abbreviations (codes) defined in the EXFOR system (e.g., "(43-TC-99-M,6.0082HR,DG,140.5,0.885)" for emission probability of the 140.5 keV gamma emission probability (88.5%) for 99mTc with T1/2=6.0082 h), and it is not always trivial to understand the full contents of the EXFOR file by reading by eyes. Reading of EXFOR files by modern computer codes also becomes more challenging since the EXFOR format was intended to be interpreted by Fortran codes and younger generations usually opt other modern computer languages such as Python. Accessibility by computer codes would be also important for AI application to nuclear data analysis.

To improve readability of the information stored in the EXFOR library with keeping the original format for data compilation and exchange, an attempt was made to convert EXFOR files to JSON (JavaScript Object Notation), which is human readable but also routinely used for data exchange and reading by computer codes. The converted JSON files (J4, https://nds.iaea.org/nrdc/exfor-master/j4/) are publicly available, and an open source Python program for conversion from EXFOR to J4 (X4TOJ4) is also freely available as a part of the ForEXy package (https://pypi.org/project/forexy/) [2].

As a first application of the J4 files, we applied them for evaluation of 237Np fast neutron fission cross section with least-squares analysis considering covariances in experimental cross sections. Similar evaluation technique has been applied to development of recommended medical isotope production cross sections at the IAEA, and it would be meaningful to extend the scope of J4 application to isotope production and other application fields.

This paper will report development of tools converting EXFOR for better readability by eyes (X4VIEW) and by computer programs (X4TOC6) with some examples taken from isotope production cross sections.

References
[1] N.Otuka et al.,"Towards a more complete and accurate experimental nuclear reaction data library (EXFOR): International collaboration between Nuclear Reaction Data Centres (NRDC)", Nucl. Data Sheets 120(2014)272.
[2] N.Otuka et al.,“EXFOR utility codes (ForEXy) and their application to neutron fission cross section evaluation”, Appl.Radiat.Isot.225(2025)111903.

Speaker: Dr Naohiko Otuka (International Atomic Energy Agency)

11:40 AM Developing a ¹⁶⁶Dy/¹⁶⁶Ho-generator using acidic alumina separation

Aim
Holmium-166 ($^{166}$Ho) is a promising radionuclide for targeted radionuclide therapy. The combination of its high energy beta radiation for treatment and low energy gamma radiation for imaging makes it suitable for theragnostic purposes. Unfortunately, this radionuclide is not widely used yet because it remains difficult to obtain $^{166}$Ho in high enough specific activity to allow application in targeted radionuclide therapy.

In this work, we aim to develop a $^{166}$Dy/$^{166}$Ho generator to produce $^{166}$Ho of high specific activity. Unfortunately, the separation of lanthanides is notoriously difficult, especially for adjacent lanthanides such as Dy and Ho. To overcome this limitation, we aim to use hot atom effects that take place upon the decay from $^{166}$Dy to $^{166}$Ho. In this decay, Auger electrons are emitted, leading to highly charged $^{166}$Ho atoms. These atoms will subsequently compensate for the electron loss by scavenging electrons from their surroundings. This ‘post decay-effect’ causes the destruction of any ligands to which $^{166}$Ho may have been chelated. Therefore, by chelating [$^{166}$Dy]Dy to suitable chelators and waiting for it to decay to $^{166}$Ho, the newly formed $^{166}$Ho can be separated from the [$^{166}$Dy]Dy-complex. For this separation, a column material is needed that retains complexed [$^{166}$Dy]Dy, but not free $^{166}$Ho which can then be eluted, ultimately resulting in high specific activity $^{166}$Ho.

Materials & methods
3 mg Dy$_2$O$_3$ was irradiated in the Hoger Onderwijs Facility of the TU Delft, resulting in 18.7 MBq $^{166}$Dy. The irradiated [$^{166}$Dy]Dy$_2$O$_3$ was dissolved in 1 M HCl upon gentle heating. The resulting [$^{166}$Dy]DyCl$_3$ solution was complexed with 1.1 eq. 1,4,7,10-tetraaxacyclododecane-1,4,7,10-tetramethylenephosphonic acid (DOTMP) at pH 7 and transferred onto an acidic alumina anion-exchange column. After ingrowth and release of $^{166}$Ho (typically after 40-72 hrs), the column was eluted with 5x 1 mL eluent (MilliQ, pH 4.5 HCl, or 50 mM pH 4.5 acetic acid buffer) to collect the produced $^{166}$Ho. The amount of $^{166}$Ho and $^{166}$Dy in the eluted fractions were determined using a Canberra HPGe low-energy gamma detector.

Results
The complexation of [$^{166}$Dy]Dy with DOTMP resulted in a 98.9% +-0.1% yield. Acidic alumina was expected to work as a column material, because it is a positively charged material that retains the negatively charged [$^{166}$Dy]Dy-DOTMP complex. Indeed, a retention of 92% of [$^{166}$Dy]Dy on the column was achieved, confirming the suitability of the material. After ingrowth of the $^{166}$Ho-daughter, the positively charged $^{166}$Ho is not retained on the column and can be eluted. Among the different eluents tested, MilliQ water worked best with a $^{166}$Ho-elution of 24%. Most activity (17%) was concentrated in the first fraction of 1 mL. In total only 0.6% of the dysprosium was eluted along with $^{166}$Ho.

Conclusion
These experiments show the suitability of acidic alumina for the separation of $^{166}$Ho from [$^{166}$Dy]Dy. Furthermore, the chosen concept allows for a generator setup, in which 166Ho can be eluted on site and on demand. To improve the setup even further, future work will focus on reducing the co-elution of dysprosium and increasing the elution efficiency of $^{166}$Ho.

Speaker: Marouscha Puister

12:00 PM → 1:30 PM Lunch

12:15 PM → 1:15 PM DNRC EuChemS Annual Meeting

Convener: Jon Petter Omtvedt (University of Oslo, Department of Chemistry)

1:30 PM → 3:00 PM Actinoids and Transactinoids: TAN 2

Conveners: Christoph Düllmann, Alexander Yakushev (GSI Helmholtzzentrum für Schwerionenforschung GmbH)

1:30 PM Actinide Dioxide Nanoparticles via Hydrothermal Oxalate Decomposition: The First Decade

In 2016, our group published the pioneering results on the hydrothermal decomposition of actinide oxalates, demonstrating the successful formation of high-quality AnO$_{2}$ nanopowders (An = Th, U, and Pu). The resulting, disruptive powder engineering method consistently yields exceptionally reactive, nanocrystalline powders. These are presented as soft (sub)micrometric agglomerates exhibiting a significantly reduced particle size. The process has been validated as simple, quantitative, reproducible, rapid, and cost-effective. This foundational work immediately spurred multiple significant scientific and applied developments. Building upon this success, NpO$_{2}$ and binary (U-Th and U-Pu) or tertiary solid solutions in the Th-U-Np-Pu system were subsequently synthesized. The hydrothermal route provides a viable pathway for incorporating trivalent americium at concentrations relevant for transmutation fuels, offering a critical step toward the efficient closure of the nuclear fuel cycle. These powders have proven instrumental in the solid-state synthesis of (U,Pu)O$_{2}$ solid solutions, yielding homogeneous materials with superior density and grain structure. Submicrometric spherical agglomerates of AnO$_{2}$ with targeted size can be produced, enabling their potential use for safeguards analysis. They have also served as highly reactive precursors in the formation of porous U- or Th-carbides, subsequently utilized as irradiation targets. Ultimately, this method has definitively proven its exceptional worth and possesses substantial, yet unexplored, potential across nuclear materials science and technology.

Speaker: Dr Karin Popa (European Commission, Joint Research Centre, Karlsruhe, Germany)

2:00 PM New insights into the selective extraction of Am from a PUREX raffinate solution

Beside the separation of Plutonium and Uranium through the Plutonium-Uranium-Reduction-Extraction Process (PUREX-Process) it is considered within the European TRANSPARANT to recycle further Americium through a solvent extraction-based process and to integrate it in a Partitioning -Transmutation cycle. The main goal is to reduce the waste burden (less heat and radiotoxicity) on a future repository for high level waste. Separating americium (Am) from curium and the lanthanides (Ln) is a key challenge in the treatment of a PUREX raffinate solution during advanced nuclear fuel reprocessing (i.e partitioning). The objective is to use a CHON-based ligand, i.e. a ligand composed of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). This is to prevent further waste from entering the cycle. The focus of this work is on separating Am-241(III) from Cm-244(III) and the lanthanides, as Am-241(III) is of interest for its potential use as fuel in a transmutation device. To achieve this, N2, N9-bis(2-hydroxyethyl)-1,10-phenanthroline-2,9-dicarboxamide (2OH-DAPhen) as hydrophilic CHON-based ligand has been tested. The two-phase system includes 2OH-DAPhen in the aqueous phase and 2,2'-oxybis(N,N-dioctylacetamide) (TODGA) as an hydrophobic extractant in the organic phase. This System can achieve separation factors (Am/Cm) > 4, which would surpass the currently leading Americium selective (AmSel) process. The limits of this system were tested by examining the boundary conditions regarding acid dependence, temperature dependence, kinetics and long-term stability. Subsequently, an asymmetric diglycolamide (DGA) was also used to make a direct comparison with TODGA.

Speaker: Ms Katharina Peters (Forschungszentrum Jülich Institute of Nuclear Waste Management)

1:30 PM → 3:00 PM Nuclear Analytical Methods: NAM 2

Conveners: Jixin Qiao (Technical University of Denmark), Mojmír Němec (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry)

1:30 PM Isolation and quantification of anthropogenic, cosmogenic and interstellar radionuclides in deep-sea ferromanganese crusts

Slow-growing hydrogenetic ferromanganese crusts, occurring in all major oceans, represent exceptional geochemical archives for long-lived radionuclides on multimillion-year timescales. With growth rates of only a few millimetres per million years, these crusts form by precipitation of Fe-Mn oxyhydroxides from seawater and efficiently scavenge trace elements and radionuclides from the water column. Their layered structure enables time-resolved reconstructions of terrestrial and extraterrestrial radionuclide fluxes over the past 10–20 million years.

In this contribution, I will present recent advances in the radiochemical extraction and ultra-trace analysis of selected radionuclides in ferromanganese crusts, including ¹⁰Be, ²⁶Al, ⁵³Mn, ⁶⁰Fe, and the actinides plutonium and curium [1,2]. Emphasis will be placed on the development of tailored multi-element separation schemes capable of isolating these radionuclides from milligram- to kilogram-scale crust samples with high chemical yields, despite the presence of rare-earth elements at concentrations ranging from 100 ppm to the permil level.

The unique detection capabilities of accelerator mass spectrometry (AMS), including molecule destruction, isobar suppression and atom counting at isotopic ratios down to 10⁻¹⁶–10⁻¹⁷, allow the identification of minute anthropogenic, cosmogenic and interstellar signatures preserved in these archives. I will highlight the recent discovery of a pronounced cosmogenic ¹⁰Be anomaly in several Pacific ferromanganese crusts [3], as well as ongoing efforts to detect interstellar radionuclides in the crust VA13/2-237KD [4]. These results demonstrate how combining advanced radiochemistry and state-of-the-art AMS provide powerful tools to address key questions in astrophysics, environmental processes, and geochronology.

References
[1] D. Koll et al. NIMB. 2022, 530, 53-58.
[2] S. Fichter et al. Front. Environ. Chem. 2024, 5:1379862.
[3] D. Koll et al. Nat. Commun. 2025, 16, 866.
[4] D. Koll et al. Nat. Astron. 2026, accepted.

Speaker: Dominik Koll (Australian National University & Helmholtz-Zentrum Dresden-Rossendorf)

1:48 PM Optimization of ⁴¹Ca determination using 300 kV accelerator mass spectrometry at MILEA

During the decommissioning of nuclear facilities, dismantled materials must be characterised and managed with regard to long-lived radionuclides that may influence radioactive waste behaviour and its environmental impact. In addition to radionuclides accessible by conventional radiometric techniques, particular attention must be paid to difficult-to-measure radionuclides. One such nuclide is 41Ca, produced predominantly by neutron activation of stable 40Ca, which decays by electron capture to stable 41K with the emission of low-energy X-rays and Auger electrons and has a half-life of approximately 100,000 years. Although the emitted radiation is of low energy, 41Ca is of concern due to the high mobility of calcium in environmental compartments. In recent years, mass spectrometric techniques, especially accelerator mass spectrometry (AMS), have become the method of choice for 41Ca determination, enabling 41Ca/40Ca isotopic ratio measurements down to the order of 10-15, while radiometric methods remain applicable mainly to samples with high specific activity. While existing AMS facilities are capable of analysing natural samples, this work focuses on the development of a methodology for 41Ca determination using low-energy AMS systems. An important part of this effort is the optimisation of the AMS MILEA system, which, in combination with an optimized and comprehensive chemical separation of 41K as the dominant isobaric interference, aims to mitigate the inherently higher detection limits of low-energy AMS and improve the overall sensitivity of 41Ca measurements.

Acknowledgement:
This work was co-funded by the European Union under Grant Agreement n°101166718.

Speaker: Filip Babčický

2:06 PM Simultaneous Analytical Method for ²³⁷Np, Pu isotopes, ²⁴¹Am and ²⁴⁴Cm in small‑size seawater using 300 kV AMS system

Since nuclear activities commenced in 1945, significant quantities of anthropogenic radionuclides have been released into the environment. Approximately 70% of Earth’s surface is covered by oceans which are the main reservoir for such radioactive fallouts. Long-lived radionuclides, such as 239Pu, 240Pu, 237Np, 241Am and 244Cm have been used as tracers to investigate the marine dynamics and to monitor their distributions. The analysis of such isotopes is, however, challenging due to their low concentrations, and matrices which interfere with analytical results. This study aims to improve such restrictions using a single-column ion chromatography and Accelerator Mass Spectrometry with a 300 kV Multi-Isotope Low Energy AMS system (AMS-MILEA).
Based on the highly sensitive mass spectrometry, a simultaneous analytical method for Pu isotopes, 237Np, 241Am, 244Cm in small-volume seawater samples was established. Two steps of hydrated titanium oxide (HTiO) co-precipitation were first performed to remove most matrix components, with pH adjusted to 9.5 using 8 mol/L NaOH and concentrated NH3·H2O, respectively. TK200 and DGA resin columns were selected for the simultaneous separation and purification of Pu, Np, Am, and Cm. The results demonstrated high and robust chemical yields exceeding 88%, with the Np/Pu yield ratio ranging from 0.98 to 1.02 and 0.98-1.01 of Am/Cm. Furthermore, stable differentiation coefficients were achieved for AMS measurements, which were 1.27 for 237Np/242Pu and 0.41 for 244Cm/243Am. The method was validated using 20 L seawater samples spiked with 239Pu and 237Np standard solutions, or the certified reference material IAEA 484. The deviations of the spiked samples for 239Pu, 237Np, and 241Am ranged from -25.89% to 5.09%, and the measured values were in good agreement with the reference values. Under the optimized AMS measurement conditions, the detection limits for a 20 L water sample were estimated to be 0.097 fg for 237Np, 0.080 fg for 239Pu, 0.078 fg for 240Pu, 0.073 fg for 241Pu, 0.107 fg for 241Am, and 0.004 fg for 244Cm. This method can be applied to the background level monitoring and tracer studies of Pu, Np, Am, and Cm in environmental seawater.

Speaker: Yang Wu (China Institute for Radiation Protection)

2:24 PM Development of a simultaneous measurement method for actinides by laser ablation coupled to inductively coupled plasma triple quadrupole mass spectrometry (LA-ICP MS/MS)

In the field of nuclear safety and radiological environmental monitoring, the actinides (An), particularly thorium, uranium, neptunium, plutonium and americium need to be monitored. As the presence of actinides in the environment is generally low, analysis to detect these radionuclides requires time-consuming and costly chemical separation procedures prior to measurement by mass spectrometry or alpha spectrometry. These steps are essential to preconcentrate the radionuclides of interest, and to reduce spectral interferences during measurement by both mass spectrometric and radiometric technique (alpha spectrometry). In case of an accidental release of actinides in the environment, an optimized turnaround time is required to detect and identify actinides. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) equipped with a Collision Reaction Cell (CRC) minimizes the sample preparation steps required for the chemical extraction of target elements. The addition of a reaction gas in the CRC helps to resolve spectral interferences. However, even with the use of the CRC technology, some interferences could persist, primarily due to the recombination of matrix elements with oxygen, hydrogen, argon, and others. In the last decade, the introduction of tandem quadrupole mass spectrometry (ICP-MS/MS) was a major breakthrough. The improved sensitivity, combined with the addition of a mass filter upstream of the CRC, enables more effective suppression of polyatomic and isobaric interferences, resulting in improved detection limits while avoiding the need for chemical separation. In this work, we present the capabilities of the ICP-MS/MS to resolve spectral interferences during multi-isotopic actinide analysis.
A method was first developed with liquid introduction to simultaneously quantify actinides in environmental samples using alkaline fusion (Lithium meta/tetraborate flux) followed by dissolution in nitric acid and dilution before introduction in the ICP-MS/MS. Figure of merits were determined for this method for thorium, uranium, plutonium and americium and will be discussed during the presentation.
To improve the turnaround time of the method and to reduce the amount of waste generated, a new approach was developed. This involves the coupling of laser ablation with ICP-MS/MS (LA-ICP-MS/MS) to directly ablate fusion beads and introduce the sample into the mass spectrometer, thereby eliminating the need for dissolution and conventional liquid sample introduction. For this, alkaline fusion was optimized to reduce the sample to flux ratio and limit the dilution of the sample while keeping a homogeneous bead suitable for a quantitative analysis. Laser parameters were optimized for bead ablation to produce a suitable aerosol for ICP-MS/MS analysis. In this work, two different laser systems were compared, a 257 nm femtosecond laser and a 193 nm nanosecond laser. Laser optimizations and method performances will be discussed during the presentation.
This newly developed method was evaluated on certified reference materials (CRMs) and proficiency test environmental samples for speed and accuracy. The current method based on alkaline fusion bead preparation coupled with LA-ICP-MS/MS enables a rapid turnaround time (<3 hours for 6 samples) while achieving quantification limits that meet the European regulation on maximum permitted levels of radioactive contamination (Council Regulation (Euratom) 2016/52 of 15 January 2016)

Speaker: Mr Jeremy Marechal (Autorité de Sureté Nucléaire et de Radioprotection (ASNR), PSE-ENV/SAME/LERCA, F-78110, Le Vésinet, France.)

2:42 PM Determining ²³⁶U, ²³⁹Pu and ²⁴⁰Pu concentrations, along with ²³⁶U/²³⁸U, ²³⁶U/²³⁹Pu and ²⁴⁰Pu/²³⁹Pu ratios by quadrupole mass spectrometry – methodological considerations

Current practice primarily limits routine control of the radiological situation to radioisotopes identifiable by gamma spectrometry. Given the potential for selective release of radioactive contamination, particularly alpha emitters, the existing monitoring strategy may be insufficient to detect nuclear events. Therefore, a key recommendation for nationwide and international nuclear safety monitoring networks is to incorporate regular measurements of pure beta and alpha emitters across all environmental media. In light of these concerns, we developed and implemented a rapid method to determine $^{236}\mathrm{U}$, $^{239}\mathrm{Pu}$ and $^{240}\mathrm{Pu}$ concentrations, along with $^{236}\mathrm{U}$/$^{238}\mathrm{U}$, $^{236}\mathrm{U}$/$^{239}\mathrm{Pu}$ and $^{240}\mathrm{Pu}$/$^{239}\mathrm{Pu}$ ratios, using the Agilent 8900#100 ICP MS/MS (Agilent Technologies) in conjunction with the Apex IR desolvating nebuliser (Elemental Scientific). Prior to measurement, a sequential radiochemical procedure was employed, encompassing incineration at 600 °C, microwave mineralisation and separations on TEVA and UTEVA resins (Triskem International). Chemical yield was checked by a $^{242}\mathrm{Pu}$ spike (SRM 4334j, NIST) for the Pu fraction and by double determination of $^{235}\mathrm{U}$ content in the analysed sample for the U fraction. Method calibration and validation, spectrometry tuning, and necessary corrections were performed by measurements of multiple standards and reference materials, as outlined below. Standardised solutions of $^{239}\mathrm{Pu}$ (SRM 4330c, NIST) and natural U (4321d, NIST) were applied for method optimisation. External mass bias correction, monitored by measuring certified ratios of $^{239}\mathrm{Pu}$/$^{242}\mathrm{Pu}$ (IRMM 290-A1, EC-JRC), $^{235}\mathrm{U}$/$^{238}\mathrm{U}$ (IRMM 074/6, EC-JRC) and $^{233}\mathrm{U}$/$^{236}\mathrm{U}$ (IRMM 3636b, EC-JRC), was calculated using the exponential law. The bias corresponding to the combined pulse counting and analogue detection modes was corrected based on measurement of the $^{233}\mathrm{U}$/$^{235}\mathrm{U}$ ratio (IRMM 074/6, EC-JRC). Reference materials of IAEA-385, IAEA-447 (IAEA), and IRMM 3020a (EC-JRC) were used for quality assurance. The measurements were conducted in energy-discrimination or mass-shift modes, using He or $O_2$ gases in the collision-reaction cell, respectively. This setup provided a spectrometric sensitivity of over 4000 cps/ppt and reduced polyatomic interferences, primarily $^{235}\mathrm{U}$$^{1}\mathrm{H}^+$ and $^{238}\mathrm{U}$$^{1}\mathrm{H}^+$, by $10^8$ times. The LOD was calculated to be equivalent to a few femtograms (< 10 fg) of the radionuclides examined. Chemical recoveries ranged from 70 to 80% for the Pu and U fractions. Our approach was successfully tested on cryoconite and air filter samples, yielding not only activity concentrations of $^{236}\mathrm{U}$, $^{239}\mathrm{Pu}$ and $^{240}\mathrm{Pu}$, but also atomic ratios of $^{236}\mathrm{U}$/$^{238}\mathrm{U}$, $^{236}\mathrm{U}$/$^{239}\mathrm{Pu}$ and $^{240}\mathrm{Pu}$/$^{239}\mathrm{Pu}$.

Speaker: Dr Anna Cwanek (Institute of Nuclear Physics, Polish Academy of Sciences)

3:00 PM → 3:30 PM Coffee Break

3:30 PM → 5:00 PM Environmental Radioactivity: RER 2

Conveners: Ana Noguera (Centro Universitario Regional del Este, Universidad de la República), Nick Evans (Nottingham Trent University)

3:30 PM Colloid-Facilitated Transport of Uranium Elevates Environmental Risk: A Key Challenge for Immobilization-Based Remediation

The occurrence forms and migration behaviors of uranium in the environment are crucial for the environmental safety assessment around nuclear facilities. Based on the geochemical process of uranium in the environment, remediation strategies including phosphoric agents, reductive agents, as well as reductive bacteria treatment, have been proposed to immobilize uranium in the contaminated sites. The solutes migration models have been constructed to describe and predict the uranium migration ability and then evaluate the effectiveness of immobilization remediation. However, the migration distance of on-site monitoring is often greater than the predicted migration distance, studies have revealed that the colloids mediated transport contribute an important role in radionuclide migration. Uranium, on the one hand, is prone to form the intrinsic colloids under groundwater conditions due to its nucleation and crystallization process; on the other hand, it easily associates with the widely existed environmental colloids to form the pseudo colloids. The existence of colloidal stated uranium significantly affects the transport patterns and the environmental risk, which should be given critical consideration when assessing the remediation effectiveness on a uranium contaminated site. This presentation aims at the environmental risk and the immobilization effectiveness adjacent to uranium contaminated sites, the uranium transport abilities under the phosphoric or reductive media are discussed at the absence and presence of environmental colloids, the transport occurrence and mechanism of uranium are clarified with the aid of advanced spectroscopic evidences as well as theoretical calculation, the role of colloidal state uranium, including both intrinsic and pseudo uranium colloids, are identified and described. Relevant achievements provide theoretical basis and support for the reliable assessment on nuclear environmental safety around uranium contaminated sites.

Speaker: Duoqiang Pan

4:00 PM Cobalt and europium adsorption on nanoplastic particles

The intensive production and use of plastics in industry, medicine, and daily life have led to environmental pollution by various plastics. Fragmentation and degradation of plastic particles entering the environment result in the formation of microplastics (< 5 µm) and nanoplastics (< 1000 nm), which are not only smaller but also exhibit higher bioavailability, migration rates, and the ability to adsorb various pollutants, including metals and radionuclides. Nanoplastic particles carrying pollutants are more harmful because they can transport these substances in the environment and into living organisms. This research aimed to study the adsorption of Co²⁺ and Eu³⁺ on real-life nanoplastics (NPs) prepared from single-use plastic bottles and packaging materials by mechanical fragmentation and nanoprecipitation. Polystyrene (PS) and polyethylene terephthalate (PET) samples were characterised by SEM, TEM, and ATR-FTIR. Adsorption was studied in batch experiments using EuCl₃ and CoCl₂ solutions traced with ¹⁵²Eu and ⁶⁰Co, respectively. The activity concentrations of ⁶⁰Co and ¹⁵²Eu were measured by gamma spectrometry with HPGe detectors. The maximum adsorption efficiency for cobalt and europium on NPs ranged from 80% to 100%, depending on concentration, particle size, and experimental conditions. High efficiency for ⁶⁰Co and ¹⁵²Eu adsorption on the NPs was also observed in natural seawater. The experimental data were mostly in better agreement with the Langmuir isotherm model and the pseudo-second-order non-linear kinetic model. The data and modelling indicated a complex mechanism controlling the adsorption of ⁶⁰Co and ¹⁵²Eu on NPs. Adsorption on NPs was analysed using XPS, ATR-FTIR, and Raman spectroscopy. The results indicate a high adsorption potential of the NPs for ⁶⁰Co and ¹⁵²Eu and complex behaviour in the environment.
Acknowledgment: Research council of Lithuania - Student summer internship - Nr. P-SV3-25-500

Speaker: Dr Galina Lujaniene (Center for Physical Sciences and Technology, Vilnius, Lithuania)

4:20 PM Tracing Nuclear Fallout: Questioning the dominance of weapon ¹³⁷Cs in wild boar

Wild boars in Europe exhibit an unexpectedly slow temporal decrease of the meat contamination with radiocesium originating from both nuclear weapon test fallout (NWT) and the Chornobyl accident (CA) – a phenomenon known as the wild-boar paradox. Previous estimates based on the Cs-135/Cs-137 isotopic ratios of Bavarian wild boar meat suggested that: 1. Due to different time spans available for downward migration, the older NWT radiocesium could have reached deeper soil layers than the younger CA radiocesium. Hence, NWT radiocesium was claimed to dominate the growth zone of deer truffles, one of the wild boars’ favorite food items, following that 2. CA fallout was reported to contribute a minimum of 1 % and NWT a maximum of 99 % (mean 31 %) of the total radiocesium in wild boar meat. To answer theses hypotheses, soil cores from multiple Bavarian regions were collected for depth-dependent specific activity determination using γ-spectrometry. The depth-dependent Cs-135/Cs-137 isotope ratios were measured in a representative core from the Bavarian Forest for source allocation. For this purpose, we optimized the chemical procedure for ultra-trace level environmental samples. The soil samples were leached four times (1. concentrated nitric acid; 2. - 4. concentrated aqua regia). After evaporation and redissolution, the cesium was extracted using ammonium molybdophosphate. Thereafter, interfering elements like Mo, Sb, Sn and Ba were removed by an anion and a cation exchange resin. The Cs-135/Cs-137 ratios were measured using a triple quadrupole mass spectrometer with nitrous oxide as reaction gas. We find Cs-137 specific activity in soil monotonously decreasing with depth, while the Cs-135/Cs-137 ratio and therefore, the contribution of NWT, increases slightly, as supported by a mathematical compartment model. Since the NWT radiocesium does not dominate the truffle growth zone and the increase is only small, it cannot sufficiently explain the disproportionate high NWT contribution in wild boar meat. However, we determined a new benchmark value for NWT derived Cs-135/Cs-137 ratio of 3.3 ± 0.3 at reference date 2011.03.11 in contrast to previously used value of 1.99 ± 0.19. Applying the new benchmark value to the wild boar data, the source allocation changes clearly; the minimum CA contribution changes from 1 % to 48 %, the maximum NWT contribution from 99 % to 52 % (mean 31 % to 16 %). Overall, this work answers open key questions of the wild-boar paradox.

Speaker: Tobias Blenke

4:40 PM Global fallout pattern of ¹³⁷Cs recorded in Greenland ice core: Transport, scavenging, and methodological constraints

Cesium-137 (137Cs), a key anthropogenic radionuclide from global nuclear weapons fallout, is a powerful tracer for studying long-range atmospheric transport and deposition processes. Polar ice cores, particularly from Greenland, are suitable natural archives for reconstructing these historical fallout patterns. However, the reliability of existing 137Cs records is potentially compromised by substantial analytical challenges, including ultra-low concentrations and poorly constrained losses during sample handling.
In this study we investigated the 137Cs record in an ice core collected at Camp Century, Greenland by: (1) performing gamma-ray spectrometry 225 m underground in a quasi-background-free environment; (2) quantifying and mechanistically explaining 137Cs losses during sample preparation; and (3) reconstructing a robust 137Cs deposition profile. Controlled experiments comparing raw meltwater with processed samples reveal a systematic underestimation of 137Cs activity by approximately one-half to one-third in the processed fraction. Direct measurements of storage bags show activities comparable to those in the meltwater, demonstrating that significant adsorption onto low-density polyethylene (LDPE) containers—not filtration or chemical separation steps—is the dominant loss mechanism. This container-induced bias compensates for the observed deficit, suggesting that historical datasets, particularly those using pre-1975 protocols, likely underestimate true 137Cs inventories. Consequently, we recommend that future studies prioritize frozen storage. When melting is unavoidable, immediate acidification, minimized storage time, and avoidance of LDPE are critical. Where LDPE use is necessary, a full mass-balance analysis, including container leachates, is essential.
Applying these corrections, we evaluated the spatial variability of 137Cs inventories across Greenland for the main fallout period (1945–1982). Beyond the traditional perception of a decreasing trend from the mid-latitudes toward the Arctic, a more pronounced latitudinal decline is observed along the coast of Greenland. Moreover, a fast increase is evident from low-elevation surface stations to the higher-elevation inland sites studied. This enhanced deposition efficiency is attributed to orographic effects and more efficient in-cloud scavenging at this higher-elevation inland site (1887 m). Our findings underscore that rigorous methodological control is not merely a precaution but a necessity for accurately reconstructing global nuclear fallout signals and refining our understanding of pollutant transport and scavenging in Greenland. The data calls for new investigations to better understand transport and deposition patterns in Greenland and to ensure good radioprotection around legacy sites linked to global warming effects.

Speaker: Dr XUE ZHAO (Department of Environmental and Resource Engineering, Technical University of Denmark)

3:30 PM → 4:24 PM Separation & Speciation: SEP 3

Conveners: Jan John (České vysoké učení technické v Praze), Pavle Mocilac (Lanzhou University)

3:30 PM Water-Soluble Phenanthroline Masking Agent for Selective Separation of Am(III) and Ln(III) by Competitive Extraction

The increasing demand of carbon-neutral and low-cost energy has caused nuclear energy as an essential element in the overall composition of the current global power supply. Accompanied by the high-speed development of nuclear energy, the environmental problems associated with used nuclear fuel have aroused great attention. The spent fuel produced by modern light water reactors, over 98.5% of the components are mainly composed of U, Pu and lanthanides (Lns). However, it still contains less than 1wt % of minor actinides (MA) including Am, Np and Cm, which are responsible for long-standing radiotoxicity. In order to improve the long-term management safety of nuclear waste, the partitioning-transmutation strategy (P&T) was emerged and recognized as a viable global option. The proposed P&T initially partitioned the transuranic elements and long-lived fission products by the PUREX process using solvent extraction, and which was subsequently subjected to neutron bombardment for transmutation them into short-lived nuclides. For the realization of P&T strategy, the initial separation of Lns(III) from Ans(III) is an inevitable prerequisite. This is due to the fact that some lanthanide isotopes with large neutron cross sections can hinder the efficient transmutation of minor actinides.
In this work, the four novel hydrophilic soft-hard hybrid N,O-donor ligands with 2,6-pyridine dicarboxamide (DAPy) and 2,9-diamide-1,10-phenanthroline (DAPhen) skeletons were firstly designed and synthesized for selective binding of Ans(III) in aqueous phase. The known TODGA was used as lipophilic extractant for coordination of Lns(III) in organic medium. A biphasic competitive extraction for separation of Ans(III)/Lns(III) was developed using the present hydrophilic masking agents and the lipophilic TODGA extractant. The stability constants of complexes of Lns (III) with preferred DAPhen in nitric acid medium were determined through UV-Vis spectroscopic titration. To gain insight into the complexation mechanism of the present DAPhen ligands to Ans(III), DFT calculations, 1H NMR titration, luminescence titration, ESI-HRMS, and FT-IR analyses were further employed to investigate the coordination mode and bonding properties of DAPhen ligands with various Lns(III).

Speaker: Dr Ze-Yi Yan (兰州大学)

3:48 PM EBTzPhen: a new CHON-compliant ligand for the selective separation of Am(III) from Cm(III) and light lanthanides in the AmSel process

The AmSel (Americium Selective) process has been developed for the selective separation of Am(III) from PUREX (Plutonium Uranium Reduction Extraction) raffinate. It is based on the combined use of two ligands: the lipophilic TODGA, which exhibits a slight selectivity towards Cm with respect to Am, and the hydrophilic SO₃-Ph-BTBP, which instead shows the inverse selectivity. The two ligands work in a push-pull system, allowing a satisfactory separation of Am(III) from Cm(III) and all the Ln(III). At the conditions of 0.7-0.8 M HNO₃, 0.2 M TODGA, and 0.02 M SO₃-Ph-BTBP, the SF(Cm/Am) of the system is 2.5. Ethoxyethanol-bis-triazolyl-phenanthroline (EBTzPhen) is investigated as a more sustainable alternative to SO₃-Ph-BTBP, since it is only made by C, H, O and N and hence completely incinerable.
The aim of the study is to assess the extraction performance of the EBTzPhen and its selectivity towards Am, in presence of Cm and all the lanthanides. Specifically, batch experiments have been performed by contacting an equal volume of 0.2 M TODGA in 5% v/v octanol/ISANE IP-175 with nitric acid solutions containing the EBTzPhen and all the lanthanides (all but Pm, plus Y, each 10^-5 M) and spiked with Eu-152, Am-241, Cm-244. The behaviour of the system has been investigated as a function of different parameters: initial ligand concentration, initial nitric acid concentration, temperature and mixing time. Distribution ratios and separation factors are evaluated for all the ions by gamma and alpha spectrometry and ICP-MS measurements. Additionally, back-extraction tests are performed, to test the stripping capability of the ligand from a loaded organic phase.
In all tests heavy Ln are extracted almost completely into the organic phase, due to their high affinity with TODGA. On the other hand, light Ln tend to remain in the aqueous phase, with La being the most retained: EBTzPhen has to ensure not only a good selectivity towards Am with respect to Cm, but also to La. Experimental points at different HNO₃ concentration have shown an important dependency of the distribution ratios on this parameter, more than in TODGA only systems, indicating that nitrate ions also participate in complexes with the hydrophilic ligand. The optimal HNO₃ concentration was identified to be 0.3 M at room temperature (22°C): Cm and La are extracted in the organic phase, while Am is retained in the aqueous phase, with a SF(Cm/Am) of 2-2.5 and similar values for the SF(La/Am). Moreover, the variation of ligand concentration highlights a different stoichiometry for lanthanides and actinides complexes. Finally, the distribution ratios decrease more with temperature in the investigated system with respect to a TODGA only system, suggesting that, in addition to TODGA being an exothermic complexant, the EBTzPhen has an endothermic behaviour.
The results of the extraction experiments and complexation studies will be presented and discussed.
This work is funded by the European Union through the EURATOM research and training programme, project TRANSPARANT (Technological Research Action Necessary for Safe PARtitioning and Nuclear Transmutation), Grant Agreement: 101166386.

Speaker: Giulia De Amicis (Politecnico di Milano, Dipartimento di Energia, P.zza L. da Vinci 32, 20133 Milano)

4:06 PM Anodic Electrodeposition for the Separation of Radionuclides of Transition Metals

The precise identification and quantification of radionuclides is essential, for example, for monitoring emissions from nuclear installations, environmental radioactivity measurements and the decommissioning of nuclear facilities. As one of the main activation products in nuclear power plants (NPP), Co-60 complicates gamma-spectrometric analysis through the introduction of a pronounced Compton background, potentially obscuring other radionuclides present in low concentrations. Consequently, radionuclides may require separation prior to their identification and quantification, by using well-established radioanalytical methods such as ion-exchange or extraction chromatography. Less explored electrochemical separation methods using cheap carbon-based electrode materials could provide an alternative or complementary approach with distinct chemical selectivity. In previous studies, cathodic deposition was used to separate radionuclides of Ag, Sn, Sb, and Te from Co-60 containing samples. Even more efficient, however, would be the direct separation of Co-60, thereby reducing the Compton background in a single step. A possible approach to achieve this might be found in the tendency of a few metals to form poorly soluble oxide species at high oxidation states. Hence, this work explores anodic electrodeposition in a three-electrode flow-through electrolysis setup as a method for fast and selective separation of Co and other transition metals from aqueous solutions. Preliminary experiments with stable Co(II) in an acetate sulfate electrolyte resulted in separation efficiencies of > 80%. Further results and the applicability for background suppression in gamma-spectrometric measurements as well as the potential treatment of wastewater from NPPs will be discussed within this contribution.

Speaker: Sebastian Siegrist (Paul Scherrer Institut)

4:24 PM → 5:00 PM Education: EDU 1

Conveners: Jan John (České vysoké učení technické v Praze), Pavle Mocilac (Lanzhou University)

4:24 PM Future Perspectives of Nuclear and Radiochemistry Education in the New Era of the Silk Road according to Chinese Nuclear Energy Development

By the end of December 2025, China has 59 operational nuclear power units (excluding Taiwan), with a total installed capacity of ~62.48 GW, surpassing the original 2020 target of 58 GW. The training of qualified workers through the peaceful development along the New Silk Road is one of the most significant tasks for Lanzhou University, which located in the capital of Gansu province and then located at the Silk Road. In the last century, universities in China hesitated and, in some cases, stopped some nuclear education programs, we have now restarted programs in the areas of radiochemistry, nuclear technology, nuclear physics, nuclear medicine etc. Similar developments have occurred at a number of institutions outside of universities. It is clear that a faster development of nuclear sciences and radiochemistry will enlarges the labor market for skilled workers, there will be a greater demand for skilled workers and talents, and this will face some challenges and difficulties for education, although we will be able to provide for this demand. The areas of skills that are affected by this are planning, construction and running of nuclear power plants and the nuclear fuel cycle. If China is to provide for this demand, this would demand a growing workforce in nuclear technology and radiochemistry. The peaceful use of nuclear energy along the Silk Road will enhance the training of skilled workers in the areas of nuclear and radiochemistry. Chinese people love and hope to set up a peaceful world, we should ensure peaceful use of nuclear energy. We hope everyone in the world enjoy the peaceful development of nuclear.

Speaker: Prof. Wangsuo Wu

4:42 PM Development of Education in the Nuclear Sector in Slovakia: Current Challenges and Strategic Direction

The sustainable development of the nuclear sector in Slovakia is conditioned by the systematic and long-term development of education and human resource training. The "national action plan" reflects the growing demand for qualified professionals, particularly in connection with the preparation of new nuclear facilities and the implementation of advanced technologies, including SMR. An integral part of this process is also the strengthening of radiation literacy as a key element in understanding the principles of using ionizing radiation and its safe application. The capacities and structure of the education system are evaluated in the context of anticipated workforce needs. It is expected that ~ 4,000 workers will be required directly during construction, with a total of 6,000–10,000 involved overall, while long-term operation will require an additional 600–800 professionals. These figures significantly influence the demands placed on the education system and its current capacities. Vocational secondary education plays a key role, providing training for technical professions (e.g., electrician, mechanical technician). A significant challenge is increasing the attractiveness of technical fields and improving students’ scientific and radiation literacy. These needs are also reflected in the labor market, which increasingly differentiates requirements according to the level of completed education—from secondary school-trained technicians to highly qualified university specialists—while placing greater emphasis on practical skills and interdisciplinary competencies. At the higher education level, it is necessary to strengthen existing study programs in nuclear physics, nuclear chemistry, radioecology, and nuclear engineering, as well as to develop professionally oriented study programs focused on practical training. Such an approach is crucial for the systematic preparation of specialists and future leaders in the nuclear sector. An important milestone in current education is also continuing education, including lifelong learning, which responds to the needs of practice and enables reskilling and upskilling of workers in the this sector. Particular emphasis is placed on the development of flexible forms of education, especially programs leading to micro-credentials and short–study programs, which allow rapid adaptation to changing technological requirements and support the alignment of education with current industry needs.
The educational ecosystem also extends beyond the energy sector. Marginally, yet significantly, fields such as nuclear medicine and radiopharmacy are also represented, requiring specialized education for healthcare and natural science professionals. These areas broaden the application of nuclear technologies and support the interdisciplinary of education, while also contributing to the development of healthcare and applied research.
The strategy for the development of education in the nuclear sector in Slovakia is therefore based on close cooperation, integration of all levels of education, strengthening collaboration between academia and practice, the introduction of innovative teaching methods, and the popularization of nuclear science. Its implementation also includes financial instruments and investments to support new study programs, modernize infrastructure, and foster talent.
The goal is not only to meet domestic demand for professionals but also to strengthen Slovakia’s position as a regional center of excellence in nuclear education, research, and the training of qualified human resources. AK: APVV-24-0366

Speaker: Mrs Eva Viglašová (Univerzita Komenského v Bratislave, Prírodovecká fakulta, Katedra jadrovej chémie)

5:15 PM → 6:45 PM Education: Poster session

5:15 PM RadLab: The mobile student lab

Experiments are an important aspect for understanding theoretical concepts in physics education. Unfortunately, not every school has the capacity or financial resources to provide the materials needed for such experiments even though they might be part of the curriculum. This is especially a problem with radioactive materials due to time and cost consuming safety regulations.
RadLab was created to address this dilemma in the field of radioactive physics at secondary schools. It is a cargo bike which can be filled with the materials schools are missing. The inventory currently consists of eight experiments, worksheets, sample solutions and learning videos covering important aspects of the curriculum. For example: Visualize radiation with a cloud chamber, the range and shielding of ionizing radiation or study samples containing natural radioactivity.
We have some experiments available for borrowing. Alternatively, we offer to visit schools with the materials and guide students through the experiments. In addition, we have various virtual options.
Various schools in the region of Hannover have requested visits from the RadLab. Our given lessons were well received by students and teachers. Many consider using the offer in other classes or upcoming years.

Speaker: Lisa Friesen (Leibniz University Hannover)

5:18 PM Introduction of the Radiation Education Forum in Japan

Establishment
The Radiation Education Forum (hereafter, REF) was founded in 1994 by volunteer researchers and teachers interested in radiation education and the peaceful use of nuclear energy. The purpose is to improve “radiation literacy” not only of pupils and students but also of the public in Japan. At the time of the establishment, the issue of radiation education in Japan was that no instruction on radiation was included in compulsory education. The aim of REF is to disseminate reliable knowledge on energy, the environment, radiation, and nuclear power. It was officially certified as an NPO (Non-Profit Organization) in 2000.
Petition Regarding Radiation Education to the Minister of Education
The word "radiation" was removed from the Japanese Course of Study that came into effect in 1981. Calling for improvements to the Course of Study, we submitted petitions to the Ministry of Education in 1995, to the Ministry of Education and the Director General of Science and Technology Agency in 1996, and to the Ministry of Education, Culture, Sports, Science and Technology in 2005. As a result, the revised Course of Study was reintroduced radiation into junior high school science classes in 2011, revived after 30 years. Coincidentally, 2011 was the year of the Fukushima accident.
Seminars on Energy, Environment, and Radiation for School Teachers
From 2001 to 2009, seminars on issues about energy, environment, and radiation were conducted for elementary, junior high and high school teachers. The seminars aimed to help teachers properly integrate these topics into school education.
Study Sessions on Energy, Environment, and Radiation
REF has held its study sessions three times a year since 1994. Before the COVID-19 pandemic, all study sessions were held in face-to-face study. However, since 2020, THE REF has held one in face-to-face study session and two online sessions a year. Information on the topics and the lectures can be found on the REF website: https://www.ref.or.jp/.
Publications and Educational Materials
The "Newsletter" has been issued three times a year since 1994. The peer-reviewed journal "Radiation Education" has been issued annually since 1997. Back issues are available on our website.
REF also provides educational materials online for all school levels, covering basic knowledge of radiation, experiment guides, and lessons learned from the Fukushima accident.
In 2018, a DVD teaching material on radiation titled "R no Shotai (The Nature of R)" was produced and distributed to 10,204 junior high schools nationwide. The DVD has been available on YouTube since 2021.
International Conferences on Radiation Education
REF held the 1st International Symposium on Radiation Education (ISRE) in Japan in 1998.Then , ISRE conferences were held in Hungary in 2002, Japan in 2004, and Taiwan in 2008. In 2016, the conference was held in Fukushima Prefecture, Japan, considering the nuclear accident, providing an opportunity for school teachers and members of the public to reaffirm the importance of radiation education. The conference was hosted by Taiwan and held online in 2021.
Conclusions
In 2024, REF celebrated its 30th anniversary. In the history, REF contributed to the reintroduction of "radiation" in the Course of Study for compulsory education. Further, REF will continue to focus on supporting education about radiation in primary, junior high and high schools, to dispel excessive anxiety about radiation among the public and provide them with enough knowledge to "be fearful in the right way."

Speaker: Dr YOSHIMUNE OGATA (Aichi Medical University)

5:15 PM → 6:45 PM Radionuclides Production & Application: Poster session

5:15 PM Development of an Accelerator‑Based ⁶⁸Ge Production Method Using Ga‑Ni Electroplated Targets at a 30 MeV Cyclotron Facility

Our 30 MeV cyclotron facility routinely produces 123I-NaI from enriched 124Xe gas and 201Tl-TlCl from enriched 203Tl for clinical nuclear medicine applications. 123I-NaI is used for thyroid scintigraphy and 201Tl-TlCl for myocardial perfusion imaging. Routine radiopharmaceutical production processes demonstrate that our infrastructure for target preparation, irradiation, radiochemistry, and quality control is suitable for safe production.
Building on this experience, development studies for accelerator-based Ge-68 production via the ⁶⁹Ga(p,2n)⁶⁸Ge reaction have been initiated. For this purpose, Ga-Ni alloy targets with a 65/35 weight ratio were successfully prepared by electroplating onto gold backings, with thicknesses ranging from 80 to 100 µm, suitable for long-duration high-current proton irradiations.
We use solvent extraction method for Ge-68 production. The overall production workflow includes Ga-Ni target manufacturing, proton irradiation, chemical separation, and quality control. Target production and irradiation processes have been successfully completed, while optimization of the chemical separation module is ongoing. Based on experimental data and literature benchmarks, a production cycle of approximately 1 month is foreseen, yielding about 500-600 mCi of Ge-68 in a final volume of ~40 mL.
These studies demonstrate reliable cyclotron-based Ge-68 production using electroplated Ga-Ni targets at a 30 MeV facility and represents a promising route for a sustainable and decentralized supply of Ge-68, the parent radionuclide for Ga-68 generator.
This approach requires the use of organic solvents such as toluene and CCl₄- based systems, raising concerns regarding process safety and routine GMP applicability. Also some companies may find the specific activity concentration of the produced Ge-68 to be too low for loading 68Ge/68Ga generators.
To overcome these limitations, an alternative ion exchange-based separation method is currently under development. In this approach, branched DGA resin is being investigated as the primary separation medium to establish a cleaner, safer, and more sustainable production process.
Keywords: Ge-68, Ga-69(p,2n)Ge-68, 30 MeV cyclotron, Ga-Ni target, electroplating, ion exchange, B-DGA resin, I-123, Tl-201

Speaker: taylan ÖZBEY (Turkish Energy, Nuclear and Mineral Research Agency)

5:18 PM Development of a ⁵⁷Co Production Method Based on Electroplated ⁵⁸Ni Targets and DGA Resin Separation

Cobalt-57 is an essential calibration radionuclide for medical imaging systems and quality control phantoms. This work reports Co-57 production, with emphasis on enriched nickel target preparation and radiochemical separation.
The process design was guided by Monte Carlo simulations using the PHITS code, which showed that by using enriched Ni-58 significantly reduces irradiation time by approximately 65% compared to natural nickel targets. This optimization enables the production of Co-57 with a targeted radionuclidic purity of >99.5%, offering a clear advantage in terms of production efficiency and cost-effectiveness.
Enriched Ni-58 targets were prepared by electrodepositing onto silver-coated copper backings. The electrolyte composition, pH, and current density were systematically adjusted to obtain homogeneous nickel layers (35–60 µm) with good surface adhesion. In an effort to minimize handling time, a closed-loop dissolution system was implemented using a concentrated acidic medium, which successfully reduced the target dissolution time to 17 minutes.
Radiochemical separation with branched DGA resin resulted in ~88% cobalt elution, with nickel impurities below 0.1%, indicating effective nickel removal. The developed process allows routine production of Co-57 with reliable radiochemical purity and low metallic impurities.
Key words: Cobalt-57; enriched Ni-58 targets; electrodeposition; DGA resin; radiochemical separation; radionuclidic purity

Speaker: Gazi Güneş (TURKISH ENERGY, NUCLEAR AND MINERAL RESEARCH AGENCY (TENMAK))

5:21 PM Assessment of blood mineral profile in ewes using ⁶⁵ZnO‑labelled nano‑ and microparticles

Using 65ZnO radiolabeled by neutron activation analysis (NAA), this study aimed to investigate the blood mineral profile in ewes supplemented with micro and nanoscale zinc oxide. Eight Santa Ines ewe, with 10 months old and weighing 23.6 ± 2.0 kg, were used and randomly assigned to two equal treatment groups. One group received capsules containing 50 mg of 65ZnO nanoparticles (40 nm), and the other received capsules containing 50 mg of 65ZnO microparticles. After the adaptation period, the animals were transferred to metabolism cages and administered a single oral dose (average of 54.85 kBq of 65Zn), in the form of micro- or nanoscale ZnO capsules. Blood samples were collected 48 h after capsule ingestion to determine Br, Co, Fe, K, Na, Rb, Se and Zn and Zn concentrations in whole blood and plasma by NAA. A higher Se concentration was observed in the whole blood of sheep receiving 65ZnO micro microparticles compared to those receiving 65ZnO 40 nm (p=0.0942). No differences were observed for the other minerals in either whole blood or plasma. The higher Se concentration observed in whole blood of sheep receiving 65ZnO microparticles may be related to differences in zinc bioavailability between particle sizes, potentially affecting redox balance and selenium-dependent antioxidant pathways. Nano-sized ZnO, due to its higher surface area and reactivity, may alter mineral homeostasis differently from microparticles, influencing selenium distribution in blood cells. However, as the difference was only a statistical trend (p = 0.0942), further studies with a larger sample size are necessary to confirm this interaction

Speaker: Elisabete De Nadai Fernandes (Nuclear Energy Center for Agriculture, University of São Paulo)

5:24 PM HPLC Investigation of 211At in Aqueous Solutions under Various Experimental Conditions Relevant to Radiopharmaceutical Applications

Astatine-211 ($^{211}\mathrm{At}$) is a valuable α-emitter for targeted alpha therapy (TAT) due to its unique decay properties. It releases only a single α-particle per decay, which facilitates accurate dosimetry and produces low-energy X-rays suitable for in-vivo imaging and tracking [1]. $^{211}\mathrm{At}$ can be produced by irradiation of bismuth, a relatively abundant and low-cost material, making the raw supply relatively accessible. However, its short half-life of 7.2 hours limits long-distance transport, necessitating production at multiple facilities. Differences in target characteristics, irradiation conditions, and separation procedures among production sites may result in variations in the chemical forms of $^{211}\mathrm{At}$, potentially affecting the reproducibility of radiopharmaceutical synthesis. To address these issues, we investigated how production and separation conditions influenced the chemical species of $^{211}\mathrm{At}$ in aqueous solutions.
$^{211}\mathrm{At}$ was produced at the Research Center for Nuclear Physics (RCNP) of the University of Osaka, and Takasaki Institute for Advanced Quantum Science (QST) via the $^{209}\mathrm{Bi}$(α,2n) $^{211}\mathrm{At}$ reaction. After irradiation, $^{211}\mathrm{At}$ was isolated from the bismuth target by a dry distillation method. The irradiated target was heated to 850 °C to volatilize $^{211}\mathrm{At}$. The released $^{211}\mathrm{At}$ was transported by a carrier gas stream consisting of $\mathrm{N_2}$ or an $\mathrm{N_2/O_2}$ mixture, under either humidified or dry conditions. The transported $^{211}\mathrm{At}$ was trapped by cooling with liquid nitrogen or ice water and subsequently recovered with distilled water to obtain an aqueous solution.
Aliquots (10 μL) of the $^{211}\mathrm{At}$ aqueous solution were analyzed by HPLC with a NaI(Tl) detector. The HPLC system was equipped with a YMC J’sphere ODS-M80 reversed-phase column (4.6 mm i.d. × 250 mm) as the stationary phase. The mobile phase consisted of a 1:1 (v/v) mixture of 50 mM tetrabutylammonium phosphate and acetonitrile flown at 1 mL/min. Chromatograms were recorded for 20 min. After each analysis, 10 μL of 50 mM $\mathrm{Na_2S_2O_5}$ solution was injected to elute the residual $^{211}\mathrm{At}$ remaining on the column.
Despite differences in separation conditions, a predominant peak consistently appeared at a retention time of 5.2–5.5 min in all samples, indicating a stable chemical species of $^{211}\mathrm{At}$. However, some samples displayed one to three additional minor peaks after 6-min retention time under the same separation conditions. These additional peaks might be associated with differences in the target or irradiation parameters, suggesting that such factors influence the formation of different chemical species. The retention times of the observed peaks remained constant over time, while their intensities gradually decreased.

Speaker: Feng Yin (Institute for Radiation Sciences, The University of Osaka)

5:27 PM Secondary neutron effect in low-energy charged-particle activation cross section measurement

Charged-particle activation is a techinique to measure charged-particle induced nuclear reaction cross sections leaving radionuclides by measuring the activities of the radioactive products. When production of the radionuclides is induced not only by primary charged-particle beam particles but also by secondary particles, the contribution of the secondary particles must be taken into account. Such corrections have been sometimes done for irradiation by high energy beam particles.

Recently, we measured radionuclide production cross sections up to 50 MeV by the activation method, and found that the determined 195mPt production cross secitons below the Coulomb barrier are systematically higher than the cross sections predicted by model prediction [1,2]. We simulated the secondary neutron production process by transport calculation.

In this paper, we inroduce the discrepancy between the measured and calculated 195mPt production cross sections, and discuss whether the discrepancy can be explained by the secondary neutron production process.

References
[1] N. Otuka et al., Eur. Phys. J. A 60 (2024) 195.
[2] N. Otuka et al., Eur. Phys. J. A 61 (2025) 184.

Speaker: Naohiko Otuka (International Atomic Energy Agency)

5:30 PM ²³⁷Np production from a ²³⁸U target bombarded with protons

Radiochemical analysis of $^{237}\mathrm{Np}$ ($T_{1/2}$=2.14 Ma) is important in a number of fields, including nuclear forensics, environmental analysis, and measurements throughout the nuclear fuel cycle. However, the analysis is challenging due to the limited availability of suitable Np tracers. $^{235}\mathrm{Np}$ ($T_{1/2}$=396.1 d) was identified as a promising tracer for yield determination because of its relatively long half-life compared with other neptunium isotopes. $^{235}\mathrm{Np}$ decays by electron capture, emitting low-energy X-rays and Auger electrons that can be detected by X-ray spectrometry or liquid scintillation counting (LSC). A separate measurement of $^{237}\mathrm{Np}$ by inductively coupled plasma mass spectrometry (ICP-MS) is required. In this work, we examined options for producing $^{235}\mathrm{Np}$ via the $^{235}\mathrm{U}$(p,n)$^{235}\mathrm{Np}$ reaction in a cyclotron AIC-144. The target was a 90% enriched uranyl nitrate. Proton energies were set close to 20 MeV. After irradiation, $^{235}\mathrm{Np}$ was separated from fission products and other transuranium nuclides by ion exchange or extraction chromatography using various resins (AmberChrom 1x8, TEVA, UTEVA, TRU). An important characteristic of the $^{235}\mathrm{Np}$ tracer is its isotopic purity; the most critical impurity would be any $^{237}\mathrm{Np}$ formed as a side product by bombardment of the $^{238}\mathrm{U}$ target with protons in the reaction $^{238}\mathrm{U}$(p,2n)$^{237}\mathrm{Np}$. Besides developing an efficient separation method, optimising irradiation conditions to ensure the necessary radiopurity was the main aim of the present study.

Speaker: Dr Anna Cwanek (Institute of Nuclear Physics, Polish Academy of Sciences)

5:33 PM Chromatographic analysis of astatine-211 methanol solutions

Astatine-211 ($^{211}$At) is a promising radionuclide for targeted alpha therapy. However, its short half-life (7.2 h) necessitates a decentralized production network. In Japan, multiple cyclotron facilities enable such distribution. Nevertheless, differences in target characteristics, irradiation parameters, and purification procedures may alter the chemical species of $^{211}$At, potentially affecting radiolabeling efficiency. To ensure reproducible radiopharmaceutical synthesis, standardization of chemical quality is essential. In this study, we investigated how production and purification conditions influence the chemical forms of $^{211}$At in methanol solutions using chromatographic analysis using the HPLC and LC/MS systems.
$^{211}$At was produced at the Research Center Nuclear Physics, the University of Osaka, and at the Takasaki Institute for Advanced Quantum Science, National Institute for Quantum Science and Technology. The produced isotope was isolated from the Bi targets by a dry distillation technique using N$_{2}$ or N$_{2}$/O$_{2}$ carrier gases and was collected in 150$-$200 $\mu$L of methanol. A 10 $\mu$L aliquot of the $^{211}$At methanol solution was injected into an HPLC system equipped with a YMC J’sphere ODS-M80 reversed-phase column (4.6 mm i.d. $\times$ 250 mm) and a NaI(Tl) detector. A mobile phase was a 1:1 (v/v) mixture of 50 mM tetrabutylammonium phosphate (pH 3.7) and MeCN flown at 1 mL/min flow rate. After the analysis, 10 $\mu$L of 50 mM Na$_{2}$S$_{2}$O$_{5}$ solution was injected to rinse the column. An LC/MS system was also employed to deduce the chemical species presented in the solutions.
Regardless of the production site or separation conditions, the chromatograms generally exhibited a predominant single component, typically accounting for 70$-$80% of the total radioactivity. The fraction of $^{211}$At adsorbed on the column, evaluated from the amount eluted with 50 mM Na$_{2}$S$_{2}$O$_{5}$ solution, was <10%. The adsorbed astatine was thus considered to be eluted in a reduced form. In contrast, the chemical species of $^{211}$At in methanol solutions is under analysis.

Speaker: Masashi Murakami (Institute for Radiation Sciences, The University of Osaka)

5:36 PM Adsorption and Separation Behavior of Yttrium from Strontium in Acid Solution Using DODGAA-Impregnated Adsorbent

Our previous research showed that Sr(II) can be separated from simulated high level-liquid waste (HLLW) using extraction chromatography with distilled water as elution solution. In order to utilize the large amounts of 90Sr separated from HLLW, it is expected that 90Y, a daughter nuclide of 90Sr, will be separated from 90Sr-90Y group and used as a radioactive material in the medical field. For this purpose, a macroporous silica-based DODGAA/SiO2-P adsorbent was synthesized by impregnating an SiO2-P support with a DODGAA (N,N-Di-n-octyl-3-oxapentanedioic Acid Monoamide) extractant. The adsorption and separation behavior of Sr(II) and Y(III) on adsorbent in nitric and hydrochloric acid solutions were investigated using batch and column methods.
Adsorption behavior of Sr(II) and Y(III) ions onto adsorbent was examined using batch method. 0.2 g weighed quantity of dry adsorbent was mixed into a 13.5 cm3 glass flask with 4 cm3 liquid phase solution under 5 hour contact time in a thermostatic bath. This solution contained 5mM of Sr(II) and Y(III) ions in different concentrations of nitric and hydrochloric acid solutions. After the resultant mixture was separated through vacuum filtration, concentrations of metal ions in the liquid phase were determined by inductively coupled plasma–atomic emission spectrometer. Separation experiments of Sr(II) and Y(III) in nitric and hydrochloric acid solutions were conducted using a chromatographic partitioning apparatus.
The adsorption behavior of Sr(II) and Y(III) ions onto a DODGAA/SiO2-P adsorbent was investigated by batch methods under various contact times, nitric and hydrochloric acid concentrations, and phase ratios at 298 K. Furthermore, the separation behavior by extraction chromatography was studied by column method. Under experimental conditions, this adsorbent was found to exhibit high adsorption affinity for Y(III) and weak adsorption capacity for Sr(II). Considering the complex desorption behavior of Y(III) from adsorbents our previous studies, the separation of Y(III) and Sr(II) from HNO3 solutions using DODGAA/SiO2-P adsorbent may be possible in further extraction chromatography experiment.

Speaker: Kai Taneichi (Japan Nuclear Fuel Chemical Analysis Co., Ltd.)

5:39 PM Gamma-Recoil Survival of Neutron-Activated Gold Complexes

Neutron Activation involves the emission of prompt gamma rays, which impart recoil energy to the activated nucleus and can induce structural perturbations in molecular systems. This gamma-recoil process is generally expected to cause bond cleavage or ligand dissociation, thereby compromising molecular integrity. However, the extent to which molecular structures can survive such processes has not been quantitatively established. In this study, we investigated the survival of coordination complexes following gamma emission, focusing on gold complexes as model systems.
Gold complexes sealed in quartz tubes were irradiated by neutrons with an average flux of 3×10¹³ n/cm²·s for 1 h at the Kyoto University Research Reactor. The irradiated samples were recovered with 1 mL of acetone, evaporated to dryness, and dissolved in 0.5 mL of acetonitrile. High-performance liquid chromatography (HPLC) was used to assess the stability of the activated complexes. The system was equipped with a UV detector for identifying non-activated complexes and a gamma-ray detector for detecting activated 198Au-labeled compounds. The fraction of intact complexes was determined from the radioactivity distribution relative to the retention time.
The activated 198Au complexes were recovered using acetone. HPLC analysis showed that, for Auranofin, the main peak detected by the gamma-ray detector accounted for 74 ± 3% of the injected radioactivity. Comparison with the UV chromatogram confirmed that this peak corresponds to intact, radioactivated Auranofin. The remining ~26% of radioactivity was distributed among several minor peaks and non-eluting components, indicating the formation of decomposition products. These results demonstrate that, despite the expected bond cleavage induced by gamma-recoil, a substantial fraction of the complexes retains molecular integrity. In the conference, additional results for other gold compounds will be presented, and possible mechanisms enabling survival will be discussed.

Speaker: Atsushi Toyoshima (Institute for Radiation Sciences, the University of Osaka)

5:42 PM Preparation of a ²²⁸Ra target for ²²⁵Ac production via the ²²⁸Ra(n,γ)²²⁹Ra reaction under thermal neutron irradiation

The alpha-emitting radionuclide 225Ac has attracted considerable interest for targeted alpha therapy, a promising cancer treatment modality. Following the demonstration of its efficacy in the treatment of metastatic cancer, demand for it has surged and is expected to continue to rise. The current method for producing 225Ac relies on separating decay products from a 229Th generator; however, the limited availability of 229Th means this method is insufficient to meet the increasing demand. Therefore, the establishment of a large-scale production method for 225Ac is urgently required.
From the viewpoints of raw material availability and minimization of unwanted byproducts, such as 227Ac, a production route based on the 228Ra (n, γ) 229Ra reaction with thermal neutrons, followed by subsequent β− decays, has been proposed. The 228Ra used in this method is a daughter nuclide of 232Th, which is the constituent of natural ThO2 and is more abundant than uranium resources. Since the 228Ra (n, γ) 229Ra reaction is a single neutron capture process that does not involve spallation, the formation of impurity nuclides can be suppressed. Furthermore, the produced nuclides are limited to those in the thorium series originating from 232Th and the neptunium series originating from 229Th, formed via β− decay of 229Ra.
To develop a production process for 225Ac based on this route, it is necessary to convert chemically stable ThO2 into a soluble form and to separate trace amounts of 228Ra from bulk 232Th. Therefore, in this study, a series of processes—including the conversion of ThO2, dissolution of thorium halide in acid, separation of 228Ra from 232Th, and the fabrication of 228Ra targets supported on MgO for irradiation—were carried out, and their applicability was evaluated. The results showed that the use of CBr4 enables the thermochemical conversion of ThO2 into ThBr4, which is soluble in concentrated nitric acid, and that the use of polyvinylpolypyrrolidone as the adsorbent achieves the separation of 228Ra from bulk 232Th. Through this series of processes, the feasibility of a method for fabricating 228Ra targets supported on MgO from ThO2 was demonstrated.

Speaker: Naoki Osawa (Nagaoka University of Technology)

5:15 PM → 6:45 PM Nuclear Analytical Methods: Poster session

5:15 PM Limits of generic efficiency calibration in HPGe gamma-ray spectrometry: A multi-geometry assessment

Reliable efficiency calibration is essential for quantitative high-resolution gamma-ray spectrometry using HPGe detectors. In addition to experimental calibration with reference sources, modern spectrometric software provides generic and characterized Monte Carlo-based calibration models that enable rapid efficiency determination for a wide range of geometries. This study systematically evaluates the performance of generic and characterized efficiency calibrations implemented in Genie 2000 and Geometry Composer (LabSOCS) for three germanium detectors (two coaxial HPGe detectors and one BEGe detector) across nine commonly used sample geometries, ranging from 1 L Marinelli beakers to 30 mL vials.

Experimental efficiency calibrations using a standardized mixed-nuclide solution (Co-57, Co-60, Y-88, Ba-133, Cs-137, and Am-241) were compared with Monte Carlo-based calibrations generated using generic detector templates of different effective crystal diameters and, in the case of the BEGe detector, a single characterized detector model. Calibration performance was assessed based on activity deviations, with a success criterion defined as deviations within +/- 10%.

For coaxial HPGe detectors, generic calibrations provided good agreement with experimental data for medium- and high-energy gamma emitters when sample geometries were sufficiently centered and volumes exceeded approximately 500 mL. The optimal effective crystal diameter depended strongly on geometry: larger extended geometries favored 60 mm templates, while compact or shallow geometries were better represented by 55 mm models. Across all detectors and geometries, Am-241 (59.5 keV) consistently exhibited large deviations, reflecting dominant low-energy attenuation and dead-layer effects that are not adequately captured by generic models. Ba-133 showed pronounced deviations primarily due to cascade summation effects.

For the BEGe detector, characterized calibrations did not consistently outperform generic templates; in several geometries, generic models yielded comparable or superior agreement, suggesting that detector condition, summation effects, and operator-dependent fitting parameters can significantly influence calibration accuracy.

The results demonstrate that generic efficiency calibrations can serve as a reliable alternative to experimental calibration under well-defined geometrical and energy constraints, but their applicability is limited for low-energy emitters and extreme close-coupled geometries. Careful validation against experimental data remains essential, particularly when summation and near-surface attenuation effects are significant.

Speaker: Mrs Tereza Tomanova (University of Defence)

5:18 PM Asymmetric alpha spectra peak fit in ALF software

The asymmetric shape of alpha peak was described as analytical function in many different ways. A need of such description appears when one gets partially overlapping alpha peaks as a result of problems with alpha spectrometer resolution due to either small difference in alpha line energies or the too massive source. In our laboratory we are using more than 30 years now a software ALF which is a
modification of the P.I.M.P. gamma ray spectrum analysis program (Mietelski, Report IFJ 1410, 1989) and, like its predecessor, is written in Fortran with the use of MetaWindows graphics. It was created in 1993-8 and never was subject of publication especially devoted to it. The main difference of the ALF and P.I.M.P programs is the another analytical description of spectral lines used for peak fits. Instead of using the Gaussian function these lines are approximated by means of the following function:
N(x)=α⋅exp⁡((-(x-M)^2)/(β{|x-M|-(x-M)}+γ)) eq. 1

where: N(x) – number of counts in the x-th channel, alpha - amplitude for the maximum of the function (i.e. in the M-th channel), M - position of the maximum, beta and gamma - parameters of the spectral line shape for a given source. Notice that the function given by the above equation for x>M passes into Gaussian functions, while at a sufficiently large distance from M whereas for x<M the function when remote from M passes into an ordinary exponential function. In the fitting carried out for a single spectral line, the values of the shape parameters beta and gamma for a given source are determined by least squares matching in the successive 10 iterations of the linear approximation of the expansion into a series of functions given by the equation 1:

N(x,α,M,γ,β)=N(x,α_o,M_o,γ_(o,) β_ )+∂N/∂α dα+∂N/∂M dM+∂N/∂β dβ+∂N/∂γ dγ eq. 2
where zero indices represent the initial values of the parameters, or later, the values obtained in the previous iteration. Formally, parameters are treated as variables. Then (having as free parameters only the amplitudes (i and Mi - the positions of the maxima of successive peaks in the multiset) in the next 10 iterations the function given by equation 3, which is a linear approximation of the expansion into a series of the sum of the functions Ni(x,(i,Mi), (i.e. neglecting the terms with second and higher orders partial derivatives after the parameters (i and Mi ) :

G(x,α ⃑,M ⃑)=∑(i=1)^k▒〖N_i (x,α_i,M_i)〗=∑(i=1)^k▒〖N_i (x,A_io,M_Oi)+∑(i=1)^k▒〖(∂N_i)/(∂A_i ) dA_i 〗+∑(i=1)^k▒〖(∂N_i)/(∂M_i ) dM_i 〗〗 eq. 3
where zero indices denote the above , the parameters are formally written as components of a k-dimensional vector variable (the number of dimensions is the number of separated spectral lines). Iterations are automatically aborted if they do not converge, i.e. when the absolute values of the increments are greater than certain preset quantities. The result of the match is presented graphically on the screen as the sum of the matched functions, and the functions themselves. After acceptance by the operator, the surface area of the spectral line is calculated by integrating the numerically obtained functions N(x). The least squares algorithm is, as in the case of the PIMP program, a Cracow algorithm.

Speaker: Prof. Jerzy-Wojciech Mietelski (The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN))

5:21 PM Ultrasensitive analytical method for total Pu and Np in aerosol samples by accelerator mass spectrometry

Plutonium (Pu) and neptunium (Np) in the environment are important anthropogenic radionuclides used as tracers in environmental radioecology studies. Their isotope ratios, such as 240Pu/239Pu and 237Np/239Pu serve as distinctive indicators for identifying their sources. Existing research has validated this approach, identifying Fukushima-derived Pu in aerosols at a 120 km distance following the incident. They analyzed the isotope ratio of 240Pu/239Pu, 241Pu/239Pu and 236U/238U using accelerator mass spectrometry (AMS) and the values were employed for identification [1]. Meanwhile, conventional analytical methods struggle to detect ultra-trace, e.g. 10-15g level of Pu and Np in atmospheric aerosols in regions far from nuclear facilities, limiting the ability of monitoring their abundances and sources.
A sensitive analytical method was developed for the determination of total plutonium (Pu) and 237Np in environmental aerosol samples using a 300 kV Multi-Isotope Low Energy AMS system (MILEA). To ensure sufficient isotopic exchange between potential refractory actinide species in the samples and the yield tracers, the aerosol samples were fused with lithium metaborate. Subsequently, the sample matrices were effectively removed via hydroxide co-precipitation, followed by the simultaneous separation and purification of Pu and Np using TK200 resin columns. The average chemical recovery of the ²⁴²Pu tracer in this method exceeded 80%, with the ratio of Pu to Np recovery yields ranging from 0.98 to 1.03. The detection limits for 237Np and Pu isotopes reached 10⁻¹⁷ g per sample. This developed method has been applied to environmental monitoring and tracer studies of the atmospheric environment in China, and can also provide reliable and high-accuracy analysis for nuclear forensics.

[1] Shinonaga, T., et.al, (2014). Environ. Sci.&Technol., 48, 3808-3814.

Speaker: Yang Wu (China Institute for Radiation Protection)

5:24 PM Optimization of analytical procedures for ⁵⁵Fe and ⁶³Ni radionuclides in seawater

Following the discharge of ALPS-treated water from Japan into the ocean, there is an increasing need to establish a scientific and continuous verification system for monitoring domestic marine environments. In addition to conventional gamma-emitting radionuclide surveillance, the importance of monitoring representative beta-emitting radionuclides such as Fe-55 and Ni-63 has increased. For the accurate determination of the activity concentrations of these radionuclides, it is necessary to establish analytical procedures suitable for seawater samples. Analytical methods for Fe-55 and Ni-63 have mainly been developed and optimized for operational and decommissioning waste from nuclear facilities as well as groundwater samples.

However, few studies have focused on the determination of Fe-55 and Ni-63 in seawater. Seawater consists of approximately 96.5% water and 3.5% dissolved substances, and most dissolved components are major ions such as Cl, Na, Mg, S, Ca, and K. These high salt concentrations not only reduce separation efficiency during chemical separation based on extraction chromatography, but also increase background signals and cause matrix interferences in ICP-OES analysis used for recovery determination. Therefore, the removal of excessive salts is essential for the accurate determination of Fe-55 and Ni-63 activity concentrations in seawater samples.

In this study, an analytical procedure for Fe-55 and Ni-63 in seawater was optimized using precipitation and extraction chromatography techniques. Approximately 1 L of surface seawater, collected from the southeastern coastal area of Jeju Island in March 2023, was used for method validation. A total of 10 samples were spiked with target radionuclides (Fe-55 and Ni-63) and interfering radionuclides (Co-60 and Sr-90), and then subjected to separation and purification procedures. Chemical recoveries and radioanalytical recoveries of the purified solutions were measured using ICP-OES (SpectroArcos, AMETEK) and a liquid scintillation counter (ULLA, Hidex). Finally, the suitability and accuracy of the method were evaluated based on the recoveries of the spiked radionuclides and the decontamination factors of major ions and interfering radionuclides.

As a result, most of the excessive salinity in seawater was effectively removed, and both radionuclides achieved recovery rates exceeding the target criterion of 80%. In addition, radionuclides potentially present in treated water, including Co-60, Sr-90, and the naturally occurring radionuclide K-40, were removed to levels below background in the purified aliquots. These results indicate that the optimized procedure developed in this study is expected to enhance national capability for marine radioactivity assessment and contribute to improving the national marine environmental monitoring system in response to future nuclear-related marine discharge issues

Speaker: Ms Da-Young Kam (Korea Atomic Energy Research Institute)

5:27 PM Interference‑free separation of ⁹³Zr with TK400, ZR and TBP resins and its quantification by LSC

Zirconium‑93 is a long‑lived fission product whose complex chemistry, low‑energy beta emissions (90 keV and 60 keV), and lack of certified reference material make its quantification particularly challenging for long‑term safety assessments of radioactive waste disposals.
This work presents an interference‑free radiochemical separation scheme enabling the isolation of a pure Zr fraction free from its isobaric (⁹³Mo, ⁹³Nb) and radiometric (⁵⁵Fe) interferences, using a combination of TK400, ZR and TBP extraction chromatographic resins (Triskem). The optimization steps of the procedure were previously presented at the EUROANALYSIS 2025 conference in Barcelona during the oral contribution “Optimizing radiochemical separation for accurate measurement of ⁹³Zr in radioactive waste using TK400, ZR and TBP resins”.
In this paper, two complete separation setups (TK400/ZR and TK400/TBP) are compared in terms of purification efficiency, recovery and turnaround time. The main advantage of this approach is the retention of the interfering radionuclides on TK400 through the formation of strong anionic chloro‑complexes with the octanol extractant under concentrated HCl, while Zr passes through the resin for subsequent purification on ZR or TBP cartridges. Zr is then eluted from the respective cartridges using oxalic acid and HCl.
The purified Zr fraction will be measured by LSC (WALLAC QUANTULUS and HIDEX 300SL). For counting efficiency determination, and due to the unavailability of a ⁹³Zr certified reference material, literature mainly reports the use of ⁶³Ni as a surrogate. In addition to this approach, this work also investigates the absolute Triple-to-Double Coincidence Ratio (TDCR) method using the TDCRPy open python package, recently released for standard‑free efficiency calculations. Chemical recovery is measured by Sector Field ICP‑MS and monitored in low resolution using the ⁹¹Zr isotope from a Zr standard.
A comparison of the efficiencies obtained by the different approaches will be presented. The developed method is intended to be applied to an active sample available from the BR3 reactor.

Speaker: Flora Mbouyom (SCK CEN & VUB)

5:30 PM Actinides and ¹²⁹I analyses with the 300 kV multi‑isotope low‑energy AMS

The 300 kV Multi-Isotope Low-Energy AMS (MILEA) system was developed by ETH Zurich and Ionplus AG, Switzerland for the ultra-sensitive measurement of long-lived nuclides, such as 14C, 129I, actinides, 10Be, 26Al and 41Ca. The negatively charged ions (such as C-, I-, AnO-) were extracted from the target sample in a Cs-sputtering ion source, and injected into a low-energy analysis system, including a 90° low-energy ESA (r=534 mm) and a 90° magnet (r=450 mm). Then the ion beam was introduced into a vacuum insulated high voltage platform with the maximum acceleration voltages of 300 kV, where He gas as stripping gas was fed. Meanwhile, the incident negative ions were transformed into positive ions and the molecules were break up. After focusing of different charge states and molecular break-up products using the following electrostatic quadrupole triplet lens, the ion beam passed through the high energy side, which consists of twoagnets (90◦ and 110◦ bending angles) with a 120◦ ESA in between. While the ion currents of stable nuclides or high abundance nuclides (e.g. 12C, 127I, 235U, 238U, etc.) were measured by one of seven movable Faraday cup behind the high energy magnet 1. The rare nuclides (14C, 239Pu, 240Pu, 241Pu, 242Pu, 243Am, 241Am, 244Cm, 233U, 236U, etc.) were counted with a low noise two-anode gas ionization detector (GID).
For the determination of long-lived actinides (237Np, 239Pu, 240Pu, 241Pu, 244Pu, 241Am, 244Cm, 233U, 236U, 235/238U), An3+ ions were selected, and transmission from injector to HE cup is more than 36% at the terminal voltage of about 260 kV in accelerator. The AMS target preparation method was optimized by adding 0.4 mg Fe and 0.1 mg Ti to co-precipitate the Am and Cm, Pu and Np. The overall detection efficiencies were 8.8 × 10^-4 for Pu, 6.3 × 10^-4 for Np, 3.1× 10^-4 for Am and 7.2 × 10^-4 for Cm after 2 h of sputtering time. The correction factors of Pu/Np and Am/Cm were 1.39-1.41 and 0.39-0.43, respectively. The abundance sensitivity of 239/238 reached an optimal value of (2.1 ± 0.6) ×10^-13. For the measurement of 236U/238U ratios at (6.98 ± 0.32) ×10^-11, the single sample scatters were between 0.9% and 1.4%. For 129I measurement, the 127I transmission from injector to HE cup was more than 50.9% using I2+, and the 129I transmission from HE cup to detector was more than 95.6%. The 129I/127I ratio of WWI was (2.0-3.7) × 10^-14. For the measurement of standard solution with 129I/127I ratio at 3.98 × 10^-14, 9.95 × 10^-14, 100.37 × 10^-14, the precisions were 0.41%, 0.71%-0.75%, 0.20%-0.22%, respectively.
For dose assessment in the event of internal exposures at nuclear facilities and nuclear power plants, the analytical methods for actinides (Pu isotopes, 237Np, 241Am, 244Cm) in urine bioassay have been developed using sequential separation and AMS determination, and the detection limits obtained in this work were 10^-17-10^-18 g/d in 1.0-1.6 L of urine samples. For the environmental tracer and monitoring studies, series of analytical methods for actinides and 129I in seawater, soil, sediment, aerosol have also been developed in China Institute for Radiation Protection.

Speaker: Maoyi Luo (China Institute for Radiation Protection)

5:33 PM Neutron activation analysis as a preliminary estimate of the activation (of individual components) of concrete

Within the framework of extending the lifetime of nuclear facilities, an experiment of accelerated radiation ageing of one of the key components of the nuclear power plant, biological shielding concrete, was performed. Before the experiment itself, an analysis of the activation of its components after interactions with neutrons had to be carried out and the degree of activation of concrete, as a whole, had to be assessed. Simulations of silica aggregate activation, for example, showed strong activation of radionuclides with short, medium-long, and long half-lives (Si-31 / 2.5 hour, Ca-45 / 5 months or Fe-55 / 2.75 year, respectively).
Selected activation results of the simulation were compared with real measurements of radionuclide activity of several samples after irradiation in the LVR-15 research reactor. On their basis, it was then decided how to further handle the irradiated samples, how long it would take for them to be transported and when it would be possible to test them in the hot cells of the Research Centre Rez, with regard to the limits of the radiation load of the research infrastructure.
The activation analysis thus contributed to the implementation of an experiment of accelerated radiation ageing of a key component of a nuclear power plant in order to extend its lifetime to 60 years or more. The economic and environmental aspects of this effort are undoubtedly exceptional and contribute to the sustainability of nuclear energy and reasonable costs for its operation and decommissioning.

Speaker: Daniela Veselá (Research Centre Řež)

5:36 PM Comparative Performance Evaluation of LSC and a Semiconductor Beta Detector for Environmental Radioactivity Analysis

A liquid scintillation counter (LSC) is an instrument that measures radioactive materials by counting photons generated through the interaction between a radioactive sample and a liquid scintillation cocktail. It is commonly used for the measurement of beta-emitting radionuclides such as ⁹⁰Sr. The photons produced by the interaction between the radioactive material and the cocktail solution are detected by a photomultiplier tube (PMT) and converted into electrical signals.

The Quantulus 1220 is equipped with a 100 mm thick lead shield weighing approximately 700 kg and employs an anti-coincidence technique using guard signals to reduce background radiation, resulting in a very low background count rate. For this reason, most environmental radioactivity analysis laboratories use the Quantulus 1220 for ⁹⁰Sr analysis. The ULLA (Hidex) system offers performance comparable to that of the Quantulus 1220; however, due to its high cost and low distribution rate, it has not yet been widely adopted in the field of environmental radioactivity analysis.

More than 60 units of the Quantulus 1220 are currently in operation in Korea. Although it is a critical instrument for environmental radioactivity analysis, particularly for strontium analysis, the model has been discontinued, making maintenance increasingly difficult. In the future, instruments with comparable performance, such as the ULLA, are expected to replace the discontinued Quantulus 1220. However, due to cost and other practical considerations, it will be necessary to continue using the existing Quantulus 1220 systems for a considerable period.

To address this issue, KAERI has developed upgrade technologies for the existing Quantulus 1220 units and a semiconductor detector–based beta radionuclide detection system. In this study, the performance of the upgraded Quantulus 1220 and the beta radionuclide detector was evaluated and compared with that of the ULLA system. The results confirmed that their performance is comparable to that of the ULLA.

This work was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety(KoFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea. (No. RS-2023-00231329)

Speaker: Dr Mee Jang (Korea Atomic Energy Research Institute)

5:39 PM Detection of the radionuclide by porous scintillator

Timely and accurate monitoring of β-emitting radionuclides in water is essential for environmental safety, nuclear emergency response, and radiopharmaceutical management, yet direct detection in solution remains challenging. Here, we report two molecularly engineered metal-organic frameworks that integrate selective ion recognition with intrinsic scintillation. The tailored binding environments selectively preconcentrate β-emitting ions and confine them within chromophore-rich pores, enhancing local conversion of β-decay energy into optical signals. This enables direct aqueous detection with a sensitivity of approximately 300 Bq L⁻¹, with radionuclide enrichment and optical readout completed within 15 minutes. This integrated strategy provides a practical route for rapid, on-site sensing of ionic radionuclides in water and highlights the potential of molecularly engineered porous photonic materials for next-generation radiometric detection technologies.

Speaker: Yaxing Wang

5:42 PM Efficient recovery of ²²⁶Ra from ocean waters using strong acid cation exchange resin

$^{226}$Ra, a long-live radionuclide of the uranium decay series, plays an important role in marine radiochemistry and oceanographic tracing. In ocean waters, typical concentrations of $^{226}$Ra radioactivity are extremely low, generally on the order of 10$^{-4}$ – 10$^{-3}$ Bq·l$^{-1}$. Such low concentrations require efficient preconcentration methods and matrix separation prior to measurement. However, the complex chemical composition of the seawater matrix, especially the high concentration of competing ions, makes it difficult to selectively isolate Ra$^{2+}$ from the matrix. For this purpose, co-precipitation processes from a large sample volume are commonly used, but this method requires a lot of laboratory work, with variable levels of efficiency.
This study presents the use of a potentially simpler and more reproducible method, ion exchange using a strongly acidic cation exchanger. This requires high selectivity and sorption efficiency for the desired radionuclide. Therefore, a series of $^{226}$Ra sorptions were performed under complex environmental conditions, in this case seawater. The competitiveness against high concentrations of other ions was analysed.
Commercially available Wofatit KPS, based on a sulfonated copolymer of styrene and divinylbenzene, was used for radium separation in. To ensure natural conditions, the ‘ATI Absolute Ocean’ product, which is concentrated water from the Atlantic Ocean, was used. Column ion-exchange experiments were performed under controlled flow conditions. The analyte was a prepared solution spiked with a known amount of $^{226}$Ra, corresponding to 200 litres of water with a salinity of 30 PSU.
After sorption, the resin was dried and sealed to establish equilibrium between $^{226}$Ra and its short-lived gamma-emitting progeny. The activity was determined by gamma spectrometry with high-purity germanium (HPGe) detector.
The results obtained demonstrate high and reproducible recovery, ranging from 85 to 90%, despite elevated salinity and strong cationic competition. The average recovery rate was 88%, indicating high selectivity of the sorption material with respect to $^{226}$Ra, even when the bed was generally oversaturated (mainly Na+ ions).
Furthermore, the $^{226}$Ra content was determined in the matrix used to prepare the spiked samples. The concentration was 2.42·10$^{-4}$ ± 0,08·10$^{-4}$ Bq·l$^{-1}$, which was within the typical range for seawater.
The presented approach confirms that the ion exchange combined with gamma spectrometry provides a reliable analytical tool for the determination of $^{226}$Ra in marine systems, supporting environmental monitoring and marine radioactivity studies.

This work was financially supported by the Polish Ministry of Education and Science, grant number 501.00-210000-10000

Speaker: Filip Jędrzejek (AGH University of Krakow, Faculty of Energy and Fuels, Department of Nuclear Energy and Radiochemistry)

5:45 PM An Innovative LSC Methodology for Low-Level Tritium Monitoring to Support Sustainable Groundwater Management

Monitoring natural radioisotopes at trace concentrations, such as Tritium (³H), in groundwater sources plays a crucial role in assessing water quality and sustainable resource management, aligning with the principles of green chemistry. This study presents a procedure for determining ³H activity in groundwater samples using the Liquid Scintillation Counting (LSC) method on an ALOKA LSC 7200 system. One of the main challenges of the LSC method is the quenching effect, which reduces counting efficiency and affects the accuracy of the results. To overcome this issue, we constructed quench correction curves for ³H using two methods: the External Standard Channel Ratio (ESCR) and the Self-Constant Channel Ratio (SCCR). The study compared the accuracy of the two methods across different ³H concentration ranges, thereby identifying the threshold at which the SCCR method becomes less reliable. The results indicate that for low-activity samples, such as natural groundwater, the ESCR method provides more stable and accurate results. Since the ³H concentration in natural groundwater is often below the instrument's detection limit, the water samples were enriched 200-fold by electrolysis prior to measurement. The analytical procedure using the ESCR method successfully determined the ³H activity in the samples, with results falling within the natural background radiation range and well below the safety threshold recommended by the World Health Organization (WHO). This research confirms that the LSC method, combined with appropriate sample enrichment and quench correction techniques, is an effective and highly accurate tool for monitoring ³H in the environment, contributing practically to the field of environmental chemistry and the goal of sustainable development.
Keywords: Tritium, ³H, Groundwater, Liquid Scintillation Counting (LSC), Environmental Technology, Sustainable Water Management, Quench Correction, Environmental Monitoring.

Speaker: Sy Minh Tuan HOANG (Thu Dau Mot University)

5:48 PM Discriminating honeys from Brazilian Pantanal using neutron activation analysis

The production of wildflower honey has become increasingly scarce worldwide. Brazil possesses a great diversity of melliferous native plant species, enabling the production of large quantities of high-quality honey from Africanized bees (Apis mellifera L.), with 67,000 tons of honey produced in 2024, ranking eleventh internationally. In the Pantanal, which encompasses parts of Brazil, Bolivia, and Paraguay in the central portion of South America, the main economic activity is extensive livestock farming on native pastures, with family-based agriculture restricted to small areas. These unique aspects have contributed to making this biome the most conserved in Brazil and have also favored the registration of the first Geographical Indication (GI) for honey in the country, called Pantanal honey. Neutron activation analysis (NAA) was used to assess whether the elemental profiles of honeys of the Brazilian Pantanal allow for their geographic authentication. Honey samples were collected directly from trusted local producers in the Brazilian Pantanal. Honey bottles, typycally containing 500 g, were subjected to ultrasonic agitation for mixing, then analytical portions of 200 mg were dropped into high-purity polyethylene vials for irradiation with neutron flux in the nuclear research reactor of IPEN/CNEN. The induced radioactivity was measured by high-resolution gamma-ray spectrometry. Spectral deconvolution and mass fraction calculations were performed using the Quantu software package, based on the $\mathit{k}_{0}$-method. Data obtained was evaluated by exploratory analyses, such as cluster analysis and principal component analysis, to identify latent patterns in the elemental profile of the samples. The clustering assessment was performed with the metrics homogeneity, completeness and V-measure, which is the harmonic mean of the first two. The groups were evaluated using non-parametric statistics for each chemical element, employing the Kruskal-Wallis test to verify statistically significant differences (p-value < 0.05) and the Mann-Whitney U test as a post-hoc analysis for pairwise comparisons. The elements As, Br, Co, Cs, Fe, K, Na, Rb, Sc and Zn were taken as possible specific indicators. Consistent clustering patterns were associated with the regions of origin indicating that the elemental profile can discriminate honey samples from Pantanal biome. The results confirmed the potential of NAA, combined with multivariate statistics, as a robust tool for geographic traceability thereby contributing to the protection, valorization and consolidation of the Pantanal honey.

Speaker: Vanderlei Doniseti Acassio dos Reis (Embrapa Pantanal; CENA/USP)

5:51 PM Analytical challenges in discrimination of natural background and artificial radionuclide signatures in mobile urban gamma spectrometry for CBRN response

Rapid discrimination between natural background and artificial radionuclide signatures is a major analytical challenge in mobile gamma spectrometry used for CBRN response. In urban environments, radionuclide identification is complicated by strong spatial and temporal variability of the gamma background caused by building materials, radon progeny, NORM- containing materials and changing meteorological conditions [1,2]. Under such conditions, dose-rate elevation alone is insufficient for source attribution, and reliable interpretation requires full-spectrum analysis supported by adaptive background modelling [1,2].
This contribution addresses the principal analytical limitations of rapid field measurements in densely built environments. Particular attention is given to short acquisition times, low count statistics, source shielding, detector motion and environmentally induced peak instability, all of which reduce confidence in isotope assignment, especially for weak or partially masked sources [1,2,4]. Current approaches include spectral anomaly detection, full-spectrum comparison and machine-learning-assisted radionuclide identification [2,3]. Their practical value lies in improving discrimination between benign background variability and spectra deviating from expected background patterns [2,3].
A further issue relevant to CBRN response is operation under mixed hazard conditions. Because NaI(Tl)-based systems are sensitive to temperature-dependent spectral changes, field deployment under operational constraints increases the need for robust spectral correction and stability control [4]. The main analytical priority for mobile laboratories is therefore not only detector sensitivity, but development of explainable and field-validated workflows capable of distinguishing natural background, technologically enhanced naturally occurring radioactive material and artificial radionuclide signatures under realistic urban conditions [1-4].
References
[1] Marques L, Vale A, Vaz P. State-of-the-Art Mobile Radiation Detection Systems for
Different Scenarios. Sensors (Basel). 2021;21(4):1051. doi:10.3390/s21041051.
[2] Mukhopadhyay S, Maurer R, Wolff R, Guss P, Mitchell S. Radiation anomaly detection
algorithms for field-acquired gamma energy spectra. Proc SPIE. 2015;9593:95930S.
doi:10.1117/12.2185736.
[3] Bobin C, Bichler O, Lourenço V, Thiam C, Thévenin M. Real-time radionuclide
identification in γ-emitter mixtures based on spiking neural network. Appl Radiat Isot.
2016;109:405-409. doi:10.1016/j.apradiso.2015.12.029.
[4] Ianakiev KD, Alexandrov BS, Littlewood PB, Browne MC. Temperature behavior of
NaI(Tl) scintillation detectors. Nucl Instrum Methods Phys Res A. 2009;607(2):432-438.
doi:10.1016/j.nima.2009.02.019.

Speaker: Dr Barbara Wiaderek (Wojskowa Akademia Techniczna)

5:54 PM A Database of Terrorist Incidents Involving Hazardous Materials as a Tool for Radiological and CBRN Risk Assessment

Terrorist events involving hazardous materials are low-frequency incidents with high potential for health, environmental, and organizational impacts. Data analyses, including those based on the Global Terrorism Database, confirm the utility of structured databases in characterizing CBRN incidents [1–3]. Regarding radiological threats, the literature emphasizes the significance of radiological dispersal device (RDD) scenarios for public protection planning [4,5].
As part of the project, a structured database of terrorist events was developed as an analytical tool to support radiological and CBRN risk assessment. The database structure includes material categories, methods of use, target types, exposure mechanisms, and consequences. This approach enables the identification of patterns that support the prioritization of analytical preparedness [1–3]. It is particularly important to isolate incidents generating requirements for contamination monitoring, sampling, and material identification. The database supports radiological readiness, including mobile laboratories and early detection systems [4–6]. Its scientific value lies in transitioning from case descriptions to comparative analysis, allowing for the identification of gaps in preparedness and better-targeted radioanalytical planning for terrorist incidents [1–6].

References
[1] Santos C, Yilmaz B, Khan A, Murano T, Rubin M, Grande A, et al. Characterizing
Chemical Terrorism Incidents Collected by the Global Terrorism Database, 1970-2015.
Prehosp Disaster Med. 2019;34(4):385-392. doi:10.1017/S1049023X19004541.
[2] Aydin B. Global Characteristics of Chemical, Biological, and Radiological Poison Use in
Terrorist Attacks. Prehosp Disaster Med. 2020;35(3):320-324.
doi:10.1017/S1049023X20000394.
[3] DeLuca MA, Chai PR, Goralnick E, Erickson TB. Five Decades of Global Chemical
Terror Attacks: Data Analysis to Inform Training and Preparedness. Disaster Med Public
Health Prep. 2021;15(6):750-761. doi:10.1017/dmp.2020.332.
[4] Jeong HJ, Lim YK, Choi JR, Kim JM, Ha WH. Radiological risk assessment caused by
RDD terrorism in the metropolitan area. Appl Radiat Isot. 2013;81:237-241.
doi:10.1016/j.apradiso.2013.04.029.
[5] Saint Yves TLA, Mengersen K, Yakovlev Y, Bedwell S. Terrorist radiological dispersive
device (RDD) scenario: planning for first responders. Hum Ecol Risk Assess. 2013;19(3):562-
589. doi:10.1080/10807039.2012.707926.
[6] Calder A, Groicki S, Rowland J. Chemical, biological, radiological and nuclear
considerations in a major incident. Br J Hosp Med (Lond). 2015;76(4):C58-C63.
doi:10.12968/hmed.2015.76.4.C58.

Speaker: Klaudia Rzadkowska

5:57 PM Development of a compact analytical device based on silicon drift detector for determination of electron-capture decay radionuclides

Silicon drift detectors (SDD) are widely used in energy-dispersive X-ray analysis owing to their high resolution and high detection efficiency in detecting low-energy photons. In addition, because the detector is cooled using a Peltier element, it enables a compact device configuration. Utilizing these features, we developed a compact analytical device for electron capture decay radionuclides such as Ca-41 and Mo-93 via their characteristic X-ray emission. The analytical system was first demonstrated with Ca-41 and evaluated its applicability to the analysis of radioactive waste from the Fukushima Daiichi Nuclear Power Station (1FNPS).
Ca-41is a long half-life radionuclide, particularly emits a low X-ray emission rate, thus requiring high detection efficiency in the analytical apparatus. Therefore, an SDD with a photosensitive area of 50 mm² was used as the detector, and a movable sample stage was adopted to minimize the distance between the sample and the detector. The dimensions of the present system are W1500 mm × D3600 mm × H3200 mm, significantly reducing in size compared to conventional germanium semiconductor detectors.
The developed system was validated by measuring a Ca-41 surface source (31 Bq) emitting 3.3 keV X-rays over 1 million seconds, yielding a detection efficiency of 0.31%. Considering the established pre-treatment conditions for Ca-41, including a sample mass of 1 g and a typical chemical recovery rate of 70%, the results indicate that quantitative analysis of Ca-41 in solid radioactive samples at its trench disposal levels is feasible.
The impact of Cs-137 and Sr-90(Y-90), the major coexisting nuclides in 1FNPS waste, was characterized since Compton scattering and Bremsstrahlung radiation caused by these nuclides may raise the overall background spectrum and increase the detection limit.
This report presents the results of comprehensive evaluation and the applicability of the developed analytical device to 1FNPS radioactive waste analysis, including its dimensions, detection limit, and the effects of coexisting nuclides.

Speaker: Ayako Nitta (Japan Atomic Energy Agency)

6:00 PM Investigation of internal standards for precise determination of Ni by Liquid Electrode Plasma Atomic Emission Spectrometry (LEP-AES)

Nickel-63 is an important radionuclide when formulating policies for the processing and treatment of radioactive waste, and quantitative analysis of this nuclide is required. Because 63Ni has a relatively short half‑life, its analysis is typically performed by measuring radiation; however, since it is a pure β-emitting nuclide, chemical separation to remove co‑existing radionuclides is significant before measurement. To correct losses that occur during the separation step, a determination of the chemical recovery yield by elemental Ni analysis is needed. Conventionally, Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) is used to quantify the chemical recovery of the separation step.
In recent years, Liquid Electrode Plasma Atomic Emission Spectrometry (LEP-AES) has emerged as a promising alternative due to ICP‑AES because the instrument itself is compact, does not require exhaust equipment, operational simplicity, and low maintenance and replacement costs [1]. However, the plasma in LEP‑AES is generated from a pulsed current; consequently, the plasma is intermittent and its temperature is unstable, which leads to fluctuations in emission intensity. As a result, the relative standard deviation (RSD), is often around 7% or higher, adversely affecting the analysis accuracy for 63Ni. A common way to improve the accuracy of optical emission spectroscopy is to use an appropriate internal‑standard. In this study, we evaluated Zinc (Zn) Tellurium (Te) and Gold (Au) as internal standards for the measurement of Ni by LEP-AES. We also optimized various measurement parameters, including spectral region, applied voltage, and sample conditions, to improve the precision of Ni determinations. As a result, that Au is effective at compensating for the instability of plasma generation. In particular, the Au emission line at 242 nm exhibited good intensity stability and a strong correlation with the Ni signal, It a suitable internal standard. Under the optimized measurement conditions, we obtained calibration curves with correlation coefficients (R²) greater than ≧0.999, and the RSD for Ni at the ppm level was reduced to ≦ 2 %. Consequently, the internal standard method developed for LEP‑AES provides a rapid, simple, and highly reliable approach for Ni analysis. This technique is therefore valuable for the quantitative evaluation of 63Ni in radioactive waste analyses.

[1]Yamamoto M, Do VK, Taguchi S, Kuno T, Takamura Y. Determination of alkali and alkaline earth elements in radioactive waste generated from reprocessing plant by liquid electrode plasma optical emission spectrometry. Journal of Radioanalytical and Nuclear Chemistry. 2021;327(1):433-44.

Speaker: YUUKI MANOME (Japan Atomic Energy Agency)

6:03 PM Urban mining of rare earth elements from construction and demolition waste evaluated by neutron activation analysis

The transition toward sustainable production and consumption systems has accelerated the adoption of circular economy principles in resource-intensive sectors, particularly in the construction industry. This sector is responsible for up to 40% of global raw material consumption and approximately 35% of total solid waste generation, making construction and demolition waste (CDW) a major environmental challenge due to its high volume and heterogeneous composition. In this context, local productive arrangements (LPA) emerge as strategic frameworks for integrating regional stakeholders and promoting synergies among economic activities, waste management, and the use of locally available mineral resources. This study proposes an integrated approach combining circular economy principles with LPA, emphasizing the role of local geology associated with the occurrence of rare earth element (REE) minerals. Critical and strategic minerals are essential for the energy transition, technological innovation, and economic development as they are widely used in batteries, renewable energy systems, and electronics. Given that construction materials are commonly derived from regional geological formations, it is hypothesized that recycled construction and demolition waste (CDW-R) may contain trace amounts of REE. Thus, CDW-R is investigated as a potential secondary source within the framework of urban mining. Samples collected in Catalão (Goiás, Brazil) were subjected to comprehensive chemical characterization. Neutron activation analysis (NAA) was employed for multi-element determination, with irradiation conducted at the IEA-R1 nuclear research reactor (IPEN/CNEN, São Paulo), followed by high-resolution gamma spectrometry at CENA/USP. A total of 29 elements were determined - As, Br, Cd, Ce, Co, Cr, Cs, Cu, Eu, Fe, Hf, La, Lu, Mn, Na, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Ta, Tb, V, Yb, Zn, Th, and U. To assess the recovery potential, leaching experiments were conducted using citric acid as a green extraction agent. This weak, readily available organic acid was selected due to its low toxicity and strong chelating capacity for metal ions. The findings highlight the potential of CDW-R as an alternative resource, contributing to reduced dependence on primary mining and minimizing environmental impacts associated with waste disposal. Moreover, integrating geological knowledge with sustainable waste management within LPA can foster circular value chains at the local scale, promoting innovation and resource efficiency.

Speaker: Dr Antonio N. Zamuner Filho (Federal University of Catalão/Nuclear Energy Center for Agriculture, University of São Paulo)

6:06 PM Rapid determination of ⁹⁰Sr in seawater by automated radiochemical separation followed by TQ‑ICP‑MS

Radiostrontium (⁹⁰Sr) is a key radionuclide for rapid assessment of marine contamination following nuclear incidents. However, its determination in seawater is analytically challenging due to high salinity and severe isobaric interference from ⁹⁰Zr.
In this study, an analytical workflow for rapid determination of ⁹⁰Sr in large-volume seawater was developed by combining automated radiochemical separation and TQ-ICP-MS analysis. The radiochemical pretreatment was optimized for 2 L seawater samples using an automated two-stage separation system consisting of cation exchange preconcentration followed by extraction chromatography purification.
In parallel, analytical conditions for the determination of ⁹⁰Sr by TQ-ICP-MS were investigated to improve selectivity and minimize interference effects. Based on these optimized conditions, seawater samples spiked with ⁹⁰Sr at different concentration levels were prepared and subjected to the full analytical procedure.
The performance of the method was evaluated in terms of detection capability, reproducibility, and robustness under conditions relevant to emergency monitoring. The proposed approach provides a practical and scalable framework for the rapid determination of ⁹⁰Sr in seawater.
This method is expected to be applicable for supporting rapid decision-making in future marine radiological emergency situations.

Acknowledgements
This research was supported by Korea Institute of Marine Science & Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries (RS-2023-00256174).

Key word: Radiostrontium (⁹⁰Sr), seawater, Automated Radiochemical Separation, TQ-ICP-MS

Speaker: MyoungJung Kim (Korea Atomic Energy Research Institute)

6:09 PM Real-time Monitoring of Dynamic Distribution Coefficients in Solvent Extraction

Nuclear fuel reprocessing is an important step in the nuclear fuel cycle. Reprocessing used nuclear fuel (UNF) can separate reuseable fissile material from fission products. Other desirable elements can also be extracted from UNF, such as those used in radiopharmaceuticals. A common method for UNF reprocessing is solvent extraction (SX), where an aqueous solution containing dissolved UNF is mixed with an organic solvent to extract specific elements. As the UNF moves through the SX process, the concentration of the analyte between aqueous and organic phase changes. This concentration ratio is described by the distribution coefficient, which is a necessary parameter in modeling SX and developing future reprocessing flowsheets. The distribution coefficient is dynamic and influenced by various factors, such as acid concentration, extractant concentration, organic-aqueous ratio, etc. Understanding the distribution ratios for a SX process is very important, as it describes the extraction efficiency of the solvent as conditions vary. To develop a robust SX model, distribution ratios must be gathered for a range of conditions. This work will demonstrate a system to measure the dynamic distribution ratio by monitoring the analyte concentration in the organic and aqueous phases in an SX process, in real-time. This method will rapidly measure distribution coefficients under a variety of conditions without performing traditional, time-consuming batch shakeouts. Additionally, interstage distribution coefficients will be measured, as they influence steady state in multistage extractions but are difficult to determine using traditional methods. This will be performed using in-situ ultraviolet-visible spectroscopy in a three-stage mixer-settler system. Neodymium will be used as a surrogate for desirable elements in the PUREX/TRUEX process. The distribution coefficient will be measured as parameters are changed in the SX system, such as organic-aqueous ratio, flow rates, and acid concentration. Data from this method will be used to generate dynamic distribution ratios to feed SX models. Future work will include using this method to measure distribution ratios for novel extractants under a variety of conditions, in rapid real-time fashion.

Speaker: Adelaide Fanner (Idaho National Laboratory)

6:12 PM Simulation of different prompt gamma activation set-ups at MLZ Garching

The restart of FRM II is planned for early 2027 in thermal mode. In this work we wanted to investigate how this will affect the characteristics of the PGAA instrument which previously relied on the cold neutron source. Through McStas simulations the thermal equivalent fluxes at various positions were calculated for different guide set-ups covering the old and new elliptical guide extensions as well as the collimator using the thermal and cold neutron source. This enables the characterisation of the instrument and identification of the optimum sample position. Additionally, determining the flux distribution maps the irradiation of different sample sizes and the beam inhomogeneity can be analysed. Furthermore, the expansion of the PGAA instrument introducing the possibility of a cyclic activation analysis for short-lived isotopes was explored. The results show that using the thermal neutron source leads to a reduction of the flux by a factor of 10 to 20 for the elliptical focusing guide extensions and roughly 10 for the collimator. The optimum sample position and other characteristics were determined based on which the instrument can be employed.

Speaker: Edis Hrustanbegovic (FRM2)

6:15 PM Determination of nitrogen in powdered synthetic nanodiamonds and CVD diamonds by instrumental photon activation analysis

Keywords: nitrogen, synthetic nanodiamond, CVD diamond, instrumental photon activation analysis

Irradiation of diamonds with accelerated charged particles enhances the formation of nitrogen–vacancy (N–V) centers within the crystal lattice, which exhibit fluorescence after annealing and laser excitation. The combination of fluorescence detection with magnetic resonance imaging represents a promising non-invasive approach for biomedical imaging. Nitrogen content in synthetic powdered nanodiamonds and chemical vapour deposition (CVD) diamonds was determined using instrumental photon activation analysis (IPAA). Determination of nitrogen bound in synthetic diamonds is complicated by the presence of atmospheric nitrogen, which is also activated during irradiation. Quantification was based on detection of 511 keV annihilation γ-rays of 13N, produced via the photonuclear reaction 14N (γ, n) 13N. This radionuclide, a pure positron emitter, was produced by high-energy photon radiation (bremsstrahlung) from the MT25 microtron. Potential interference from other positron-emitting radionuclides (e.g., 15O and 11C) was minimized by optimizing irradiation parameters and decay-counting conditions. To suppress contributions from atmospheric nitrogen, various sample preparation and irradiation procedures were tested. The use of a vacuum irradiation chamber reduced the measured nitrogen content in powdered nanodiamonds from 3.03 wt.% to 0.60 wt.%. In the case of CVD diamonds from Element Six (UK) Ltd. initial measurements yielded nitrogen concentrations higher than the declared value (0.02 wt.%). Prolonged pre-irradiation heating (24 h at 250 °C under vacuum) resulted in measured values corresponding to the detection limit (0.02 wt.%), consistent with the specification. The results demonstrate that both pre-treatment conditions and sample morphology significantly influence the determined nitrogen content, with vacuum heating prior to irradiation reducing measured concentrations by approximately one order of magnitude.

Speaker: Dr Ivana Krausová (Nuclear Physics Institute of the CAS)

6:18 PM Determination of lanthanoids in NIST SRM 1547 and SRM 1573a by INAA and RNAA

Over the past several decades, the rare earth elements (REE, lanthanoids with Sc and Y included) have become the most critical and strategic elements on the planet. The increased REE demand has been driven mainly by the shift from carbon-based energy sources towards renewable clean energy. The REE mining and processing can cause severe environmental pollution, monitoring of which requires reliable and sensitive analytical methods and suitable reference materials for quality control. Despite the current prevalent use of ICP-based techniques, neutron activation analysis is still a powerful tool for REE assay.
The study presents group determination of lanthanoids in NIST (National Institute of Standards and Technology, Gaithersburg, MD, USA) biological reference materials SRM 1547 Peach Leaves and SRM 1573a Tomato Leaves using neutron activation analysis, both instrumental and radiochemical (INAA and RNAA, respectively). The RNAA procedure, developed and applied earlier at the Nuclear Physics Institute in analysis of REE polluted crops, has been based on alkaline-oxidative fusion of the irradiated samples followed by precipitation of lanthanide oxalates, with the chemical yield of separation determined by short-time neutron reactivation of the added Pr, Er and Lu inactive carriers. The results have clearly demonstrated the superiority of RNAA over INAA in lower uncertainty and detection limits, particularly for elements Pr, Nd, Tb, Ho, Yb, and Lu in SRM 1573a, and generally good agreement with the values compiled in the GeoReM database of geological and environmental reference materials (certified values are not available for the reference materials).
The work has been a part of the training programme of Y. Al Senjlawi on the RNAA techniques within the IAEA Technical Cooperation Fellowship (IAEA ref. No. FS-JOR2018-2403194) undergone at the Nuclear Physics Institute in June 2025.

Speaker: Dr Jiří Mizera (Czech Academy of Sciences, Nuclear Physics Institute)

6:21 PM Determination of hydrocarbon oil index in radioactive waste and transfer of radioactivity during sample preparation

Radioactive waste (RW) characterization is a key process for determining the physical, chemical, and radiological properties of waste for its safe separation, processing, and disposal. It includes measurements of activity, isotopic composition, and stability. However, the characterization of RW for additional pollutants is increasingly required by regulatory authorities. Organic compounds such as C10–C40 hydrocarbons (also known as hydrocarbon oil index, HOI), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) are among the most frequently monitored pollutants in the waste. This study focuses on the determination of C10–C40 hydrocarbons in various types of radioactive materials. RW contains a wide spectrum of materials including mix of matrices, that can be solid or liquid. In this study, the solid RW from mixed solid waste from a nuclear power plant (containing paper, textiles from rags, different types of plastic materials, gloves, foils, tapes etc.), contaminated rubble and liquid RW from the volume reduce solution from cleaning of nuclear power plant (NPP concentrate) were analyzed for C10-C40 contamination. During sample preparation, the transfer of radioactivity into the organic solvent (hexane) was monitored using gama-spectrometry. Monitoring radioactivity during the sample preparation allowed us to trace possible contamination and avoid unnecessary generation of secondary RW. The concentration of C10-C40 hydrocarbons was determined by GC-FID. The amount of C10-C40 was 840 mg/kg for NPP concentrate, 42300 mg/kg for mixed solid RW and contaminated rubble contained 660 mg/kg of C10-C40. Even though the samples were highly contaminated mostly by Cs (137), Am (241), Mn (54), Fe (59) and others, the measurements suggest that the radioactivity was not transferred into the hexane nor to acetone.

Speaker: Zdeňka Zachová (ÚJV Řež, a.s.)

6:24 PM Electron Accelerator Microtron MT25 as a suitable Source for Photon Activation Analysis

Technical Parameters of the Microtron MT25 Accelerator

The Microtron MT25 is a circular electron accelerator generating monoenergetic electron beams with adjustable energies between 6–25 MeV and a typical mean beam current of up to 15 μA. The pulsed beam structure is defined by a pulse length of 3.5 μs and a repetition frequency of 423 Hz. Beam dispersion is on the order of 10 keV, ensuring high monoenergeticity (<1%). The beam can be extracted to three independent experimental stations through magneto optical transport lines with adjustable beam-spot with diameter between 1–30 mm.
Bremsstrahlung is generated by directing the electron beam onto tungsten converters optimized for efficient high energy photon production. The resulting bremsstrahlung exhibits a continuous energy spectrum with an upper limit equal to the electron energy. The angular distribution of emitted photons is governed by the semi empirical relation:

$\Theta = \frac{58.6}{E} + a(E,Z)e^{-b(Z)/t}$,

where $E$ is the electron energy (MeV), $t$ is target thickness in radiation lengths, $Z$ is the atomic number, and parameters $a(E,Z)$ and $b(Z)$ describe material dependent corrections. For tungsten $(Z = 74)$, $E = 23\ \text{MeV}$, and $t = 2\ \text{mm}$ the emission cone is approximately $\Theta = 13^\circ$.
The accelerator also serves as a source of photoneutrons generated through $(\gamma,n)$ reactions in Pb or U, with yields of 2.5×10¹¹ n/s (Pb) and 5×10¹¹ n/s (U).

Photon Activation Analysis (PAA)

Photon Activation Analysis (PAA) utilizes high energy bremsstrahlung from MT25 to induce photonuclear reactions above characteristic energy thresholds. Increasing electron beam energy narrows the bremsstrahlung emission cone and enhances the flux of high energy photons capable of triggering $(\gamma,n)$, $(\gamma,p)$, and $(\gamma,\alpha) reactions. This makes the MT25 an effective irradiation source, particularly for samples of tens to hundreds of grams due to the strong penetration of high energy photons.
PAA enables determination of these elements: C, N, O, P, Na, Mg, Si, Cl, K, Ca, Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, Sn, Sb, I, Cs, Ba, Ce, Nd, Sm, Au, Tl, Pb, Th and U. Compared with Neutron Activation Analysis (NAA), PAA avoids neutron self shielding effects and is advantageous for matrices rich in neutron absorbing nuclides (B, Cd, lanthanides, Au). It also enables analysis of coarse grained geological samples (1–2 mm) and trace element determination in environmental materials.
However, PAA is less suitable for very small samples (<1 mg) and some biological matrices due to limited sensitivity for certain elements. Despite these drawbacks, PAA serves as a complementary technique to NAA or as an alternative when reactor access is limited. The MT25 microtron thus provides an efficient, high intensity source ideally suited for modern applications of photon activation analysis.

Speakers: David Chvátil (Nuclear Physics Institute CAS), Václav Olšanský (Nuclear Physics Institute CAS)

6:27 PM Validation of a method for the radiochemical separation of Mo-93 in radioactive waste using extraction chromatography and measurement of a solid sample by X-ray spectrometry

For nuclear decommissioning, the determination of 93Mo in nuclear waste is required for the disposal of waste and its management. Before measuring and determining of 93Mo, its radiochemical separation is required. This work presents the validation of a radiochemical separation method for determining the activity of 93Mo in liquid and solid nuclear waste, which is used in a radiochemical analysis testing laboratory. A sample obtained from solid radioactive waste was used to validate this method. Molybdenium-93 was separated by extraction chromatography on TEVA Resin. The presence of interfering radionuclides was sufficiently eliminated using an HF/HCl solution with added ascorbic acid. The chemical yield was determined gravimetrically using a lead molybdate precipitate. A Canberra 2008B gamma spectrometer with an SI 12155 detector was used to detect low-energy gamma rays. A mixed standard containing the gamma-emitting radionuclides 57Co, 109Cd, 133Ba, 85Sr, and 241Am, with calibration points at energies of 6.41 keV, 13.46 keV, 22.22 keV, 30.99 keV, and 59.68 keV, was used to determine the detection efficiency. For 93Mo, the energy range of 16.32 keV to 16.97 keV, with a maximum energy of 16.55 keV, was selected as the acceptable range. The accuracy and reliability of the method for determining of 93Mo activity in radioactive waste were verified by validating its performance characteristics.

Speaker: Olga Rosskopfová (Dept. of Nuclear Chemistry, FNS CU)

6:30 PM New development in Triskem: TK227 Resin

TrisKem International, ZAC de l’Eperon – 3 rue des Champs Geons, 35170-Bruz, FRANCE

The TK227 Resin, composed of TO-DGA, ionic liquid, and long-chain alcohol, has been developed to facilitate the determination of Sr-90 levels via Y-90 in seawater samples ranging from 1 to 50 liters. It may be used in the rapid determination of Sr-90 in surface waters. Compared to existing methods, the goal is to concentrate and purify Y-90 in equilibrium with Sr-90 from seawater samples acidified with HNO₃, and then collect Y-90 for measurement in less than 4 hours. The presence of the ionic liquid enhances the retention of yttrium even at low HNO$_3$ concentrations (particularly at 0.01–0.1 M HNO$_3$) compared to the standard DGA,N Resin previously used for Y-90 retention in this type of matrix. Accordingly, the TK227 Resin also allows for Y-90 concentration and purification, from surface waters acidified to 0.1M HNO$_3$, allowing rapid and easy to automate Sr-90 determination in such samples.

The characterization results, as well as application data and alternative geometry of the TK227 Resin are presented here.

Key words: TK227 Resin, Sr-90, Sr-90 separation, seawater sample

Speaker: Illarion Dovhyi (Triskem International)

6:33 PM Radiostrontium Analysis using Barium Silicate-Based Sr Sorbent II: Comparison of Various Measurement Methods

[Introduction]
Conventional analytical methods of radiostrontium are complex, time-consuming, and require hazardous reagents. Rapid and safe methods is desired. In our other presentation titled Radiostrontium Analysis using Barium Silicate-Based Sr Sorbent I, the sorption characteristics were described. Here, three measurement methods for the radiostrontium on the Sr sorbent, Pureceram MAq (hereafter P-MAq), were tried and compared.
[Methods of Measurements]
The sorbent was collected on a filter paper by suction filtration or collected in a vial by centrifugation. Three measurement methods were tried to measure according to the instrument;
(1) Low Background Gas-Flow Counter Method (LBC),
(2) Plastic Scintillation Bottle Method (PSB), and
(3) Liquid Scintillator Method (LS).
In the LBC, the sorbent on a filter paper (5C, diameter 22 mm$\phi$) was measured with a low background gas-flow counter. The permissible amount of P-MAq was 75 mg, so it can be applied to 50 mL of sample water.
In the PSB, the sorbent on a membrane filter (diameter 44 mm$\phi$) was sandwiched between a couple of disk plastic scintillator, and put in a plastic bottle. The bottle was measured with a low background liquid scintillation counter (LB-LSC). The permissible amount of P-MAq was 150 mg, applied to 100 mL of sample.
In the LS, the sorbent separated by centrifuge was put in a counting vial. Then an emulsion scintillator or a gel suspension one was added and measured with a conventional liquid scintillation counter (LSC) or a LB-LSC. Conventional LSC can measure 20 mL vial (standard), while LB-LSC can measure 140 mL vial (large). For the standard vial, the permissible amount of P-MAq was 1,500 mg, applied to 1 L of sample, whereas, for the large vial, the permissible amount of P-MAq was 7,500 mg, applied to 5 L of sample.
The minimum detectable concentration (MDC) in Bq L^-1 was calculated by Currie’s equation.
[Results and Discussions]
The chemical yield of Sr for 4 hours stirring averaged 90% for simulated seawater. The counting efficiencies of ⁹⁰Sr were 10%, 40%, 90%, and the background count rates were 0.12, 8 and 13 cpm for LBC, PSB, and LS, respectively. So, the MDC was 0.4 Bq L^-1 for LBC and PSB, and for LS, the MDCs were 0.05 and 0.01 Bq L^-1 for the standard vial and large one, respectively.
Although, the LBC has the maximum MDC, the sample volume is the minimum. So, it is easy to perform and the running cost is lowest. The LS have the minimum MDC. However, organic liquid waste is generated. Conversely, no organic liquid waste is generated by the PSB, and the plastic scintillator is reusable. One can choose the suitable method according to the circumstances of each facility, such as, the aimed MDC, the measuring instruments, available equipment you have, etc.
We are going to plan to apply this method to the analysis of radiostrontium in seawater and terrestrial water, as well as to apply to the biological analysis of human urine.
[Conclusions]
A new analysis method of radiostrontium in environmental water using a Sr sorbent was suggested. Three measurement methods were tried and compared in this report, so it is possible to select the suitable method for each facility.

Speaker: Dr YOSHIMUNE OGATA (Aichi Medical University)

8:00 PM → 9:45 PM Socials: Concert

Wed, May 13

8:30 AM → 10:00 AM Nuclear Fuel Cycle: NFC 3

Conveners: Nick Evans (Nottingham Trent University), Thorsten Stumpf (Helmholtz-Zentrum Dresden-Rossendorf e. V.)

8:30 AM How to efficiently decommission activated concrete? Radiochemical and structural investigations to support a numerical model of German NPPs

A growing number of nuclear power plants (NPPs) worldwide have been in operation for more than 40 years, and the need for efficient decommissioning strategies is ever-rising. As many nuclear countries lack a robust solution for long-term storage of radioactive waste, time and costs are crucial parameters when considering decommissioning strategies. Considerable amounts of structural waste are generated when dismantling a NPP, most of it inactive. Sorting this waste meticulously is essential to reduce the costs and occupancy rate within repositories. For this, a thorough radiological analysis of the structures is necessary. The recent developments in numerical simulations are tremendously helping the radionuclide inventory and activity mapping, and speeding up the decommissioning process. Trace elements present in concrete and steel are neutron-activated during reactor operation, and create a mix of radionuclides (RN) that remain in the structures after shutdown. To give reliable predictions on activation in the structures, the models must be refined and validated with the help of carefully selected experimental methods. Challenges rise from the difficulty of measuring some RN, namely beta-emitters, which require multi-step radiochemical separation procedures, and from the complexity of the concrete matrix.
In this study, a model of the German NPP Greifswald Unit 2 was developed with a Monte-Carlo N-Particle code. Targeted samples were taken in two positions where the highest activation is expected in the concrete biological shield surrounding the reactor pressure vessel (RPV). After building an activation depth profile of the gamma emitters relevant to the decommissioning timeframe in the concrete, namely 60Co, 152Eu and 154Eu, it was observed that 152Eu limits the release of the concrete up to 35 cm deep inside the concrete. The measured and calculated activity concentrations closer to the RPV were above the German unrestricted clearance threshold. The model was refined with precise composition measurements and the calculated and measured profiles matched commendably. The model can be considered reliable for gamma-emitters, which constitute the primary radiation concern for the workers and for the long-term storage of the waste.
An additional focus is set on difficult-to-measure radionuclides (DTM-RN), and different separation methods were developed and optimized. The main DTM-RN present in structural waste and relevant to decommissioning are 3H, 14C, 36Cl, 55Fe, 63Ni. The analysis of each RN presents its own challenges and this study aims for precise results to refine the computational model efficiently.
Beyond the determination of radionuclide inventories, their potential mobility during dismantling and storage represents an additional risk for the radiological safety and waste classification. In particular, changes in the concrete matrix over time may influence both radionuclide release and structural integrity. Therefore, a long-term leaching experiment was performed and the changes in porosity and microstructure within the concrete were monitored with computed microtomography.

Speaker: Maud Zilbermann (Helmholtz-Zentrum Dresden-Rossendorf / Institute of Resource Ecology)

9:00 AM Radiochemical Aspects in Siting of Geological Disposal Facility

Chemical conditions within geological environment contribute as one of the core aspects to the long term safety for a geological disposal facility (GDF). The siting context requires that the host rock provides geochemical stability—particularly with respect to groundwater composition, mineralogical controls and gas related processes—to ensure that radionuclide mobility remains extremely limited over geological timescales. These safety relevant aspects are formalised in a hierarchy of requirements, criteria and measurable indicators.
Requirements reflect at the first level the fact the disposal facility can be only built on the site, providing long-term safety over 100 000 years. Following that, the site has to reflect the need for a chemically favourable environment, capable of sustaining low radionuclide solubility, stable redox conditions and minimal groundwater flux. The geological setting must also moderate gas generated by corrosion, microbial activity and radiolysis, and accommodate thermal effects from natural radioelements such as U, Th and K in the host rock.
These requirements inform siting criteria applied during site selection process. Key radiochemistry relevant criteria include geochemical and mineralogical characteristics that promote sorption and retardation; transport pathway properties that ensure slow radionuclide migration; microbiological conditions, prone to low canister corrosion rates, preventing isolation of radionuclides in waste form; and gas transport behaviour that prevents over pressurisation and protects engineered barriers.
The criteria are represented by the indicators, providing transparent and measurable quantities, enabling evaluate and compare candidate GDF sites. The example can represent e.g. groundwater age, rock mineralogical composition (notably clay and secondary phases), redox potential, pH, concentrations of reactive species, microbial activity patterns, gas permeability, and thermal conductivity influenced by radiogenic heat production. As site characterisation advances, criteria might evolve to reflect increasing information about the site and data detail. Associated safety assessment, evaluating dose to the member of representative inhabitant group, provides additional element toward final decision on the GDF site.
IAEA realizes the importance of site selection and develops a publication within IAEA Nuclear Energy Series, dedicated to geological disposal facility siting process, contribution of site selection criteria, safety and environmental assessment aspects and stakeholder involvement element.

Speaker: Dr Václava Havlová (International Atomic Energy Agency)

9:20 AM THE BEHAVIOUR OF epsilon-PARTICLES IN THE SPENT NUCLEAR FUEL IN CEMENTITIOUS WATERS: RUTHENIUM RELEASE UNDER OXIDIZING AND REDUCING CONDITIONS

In a deep geological repository for spent nuclear fuel (SNF) it is assumed that after thousands of years groundwaters will reach the fuel inducing the release of a number of radionuclides coming from different parts of the fuel (gap, external grain boundaries, pre-oxidized fuel, internal grain boundaries, matrix, epsilon-particles) depending on the chemical conditions in the near-field.
Ruthenium in the SNF is present only in metallic form combined with Mo, Tc, Rh and Pd forming the so-called epsilon-particles. This metallic particles are expected to have a low solubility and a low dissolution rate and to have an important role during the dissolution of the SNF because they are believed to catalyse the H2 mediated reduction of some radionuclides.
The release of the radionuclides of the epsilon-particles in high-burnup SNF dissolution experiments have shown some interesting trends, in particular:
- The release to the solution of Mo, Tc, Ru and Rh was more than one order of magnitude higher at hyperalkaline pH than at neutral-to-alkaline pH [1]
- The release of Ru and Rh from high-burnup SNF was found to strongly depend on the presence of Calcium in the solution.
This work will show experimental studies in order to establish the reasons for the high release of Ru from SNF and in order to determine a possible precipitation of any secondary solid phase in the presence of Calcium. The experiments will consist of:
1) Ru release from a low-burnup SNF (33 MWd/t),
2) Ru release from a high-burnup SF (63 MWd/t) under reducing conditions (H2(g) atmosphere).
3) Dissolution studies of Ru(s) and RuO2(s) in the alkaline to hyperalkaline pH range. X-ray Photoelectron Spectroscopy will be used to determine Rh and Ru oxidation state in the solids after the experiments.
4) Experiments to determine the influence of calcium on the Ru chemical speciation in solution. Experiments with different Ru/Ca initial ratios will be carried out in order to evaluate the formation of Ru-Ca secondary solid phases such as CaRuO3 or CaRuO4. The solid phases formed at hyperalkaline pH and in the presence of Calcium will be characterized by RAMAN spectroscopy and X-ray Diffraction.

[1] L. Iglesias, J. Kokinda, D. Serrano-Purroy, A. Martínez-Torrents, I. Casas, J. de Pablo, F. Clarens and J. Giménez (2023). Dissolution of high burn-up spent nuclear fuel at high-pH. Radiochim. Acta 111: 817-828
[2] S. García-Gómez, J. Giménez, I. Casas, J. Llorca, J. de Pablo, A. Martínez-Torrents, F. Clarens, J. Kokinda, L. Iglesias and D. Serrano-Purroy (2024) Molybdenum release from high burnup spent nuclear fuel at alkaline and hyperalkaline pH. Nucl. Eng. Technol. 56: 34-41

Speaker: Javier Giménez (Universitat Politècnica de Catalunya (Barcelons, Spain))

9:40 AM Use of a Novel Electrochemical Gradient Technique to Simulate Radioactive ‎Contamination on Stainless Steel

Metallic surfaces, including structural components and pipework, in nuclear plants are exposed ‎‎to a wide range of temperature and chemical conditions. In these circumstances, contamination ‎of metallic surfaces with radioactive isotopes is a major ‎concern, as these isotopes can adhere ‎to the surfaces, leading to carryover of radioactivity in the process solutions and to increased ‎radiation ‎dose to workers. Moreover, at the end of the plant’s life, contamination may restrict ‎waste management options. Understanding the mechanisms behind radioactive contamination ‎is thus crucial for ‎developing effective decontamination strategies‎.‎
The preparation and analysis of radioactive samples are challenging due to radiation hazards ‎‎and the limitations of surface characterization methods but model experiments offer ‎valuable ‎opportunities to study contamination distribution on stainless steel surfaces under ‎‎representative conditions‎. Therefore, new techniques are required to accelerate the simulated ‎contamination process with electrochemically-driven methods being promising candidates for ‎controlling radioisotope deposition.‎
‎ A novel technique based on gradient electrochemistry can be used to model contamination and ‎‎‎enhance the uptake of radionuclide simulants. The modified Hull cell ‎apparatus enables the ‎study ‎of radionuclide uptake on stainless steel surfaces with a range of current densities, ‎allowing the relationship with contaminant to be established on the ‎laboratory timescale. ‎Environmental factors such as a corrosive chemical environment, ‎which may also influence ‎deposition of contaminants such as strontium on stainless ‎steel surfaces, can also be studied‎.‎
In order to explore the incorporation of contamination under realistic conditions, it is necessary ‎‎to adopt a range of methodologies to identify and localize radioactive contaminants across ‎‎stainless steel 304L surfaces. Techniques such as Liquid Scintillation Counting (LSC), ‎autoradiography, and Scanning Electron Microscopy (SEM) were examined to assess in detail ‎contamination levels, contaminant ‎behaviour, and surface morphology.‎

Speaker: Mr Khalifa Alsulami (Dalton Nuclear Institute, The University of Manchester)

8:30 AM → 10:00 AM Separation & Speciation: SEP 4

Conveners: Duoqiang Pan, Paul Dutheil

8:30 AM Controlled Synthesis of Phosphonic Acid-Based Polymers and Their Adsorption Performance for Uranium(VI) in Strongly Acidic Environments

The sustainable management of nuclear power necessitates advanced technologies for the efficient recovery of uranium(Ⅵ) from highly acidic radioactive waste streams (e.g., 4 M HNO3), a challenge exacerbated by the extreme acidity, which degrades the stability and efficacy of conventional adsorbents. This study presents a comprehensive and progressive materials development campaign aimed at overcoming this challenge. Initially, an ordered mesoporous carbon (CMK-3) supported composite CMK-3/P(DMVP) was synthesized via in-situ polymerization. By leveraging CMK-3’s robust scaffold for mechanical stability and mass transfer, this composite established a baseline for U(Ⅵ) capture in strong acid. To decouple the roles of porosity and ligand chemistry, a non-porous yet highly functionalized organic polymer, P(VPA-TEGDMA), was subsequently prepared via solvothermal copolymerization. This material exhibited an unexpectedly high adsorption capacity, underscoring the paramount importance of phosphonic acid ligand density even in the absence of traditional pore pathways. Building on this insight, a strategic enhancement was achieved through compositional engineering by incorporating a second phosphonic acid ligand, dimethyl vinylphosphonate (DMVP), to create the P(VPA-TEGDMA-DMVP) copolymer series. This mixed-ligand strategy induced synergistic effects, optimizing the polymer’s affinity and selectivity for U(Ⅵ). To address the intrinsic kinetic limitations of dense polymer networks, the final stage of the study employed Pluronic F127 as a soft template. This resulted in the successful synthesis of porous polymers, denoted as P(VPA-TEGDMA-DMVP)-F127-x, which feature tailored mesoporous structures. The introduced porosity significantly accelerated uranium ion diffusion, enhancing adsorption kinetics while preserving the high capacity endowed by the optimized chemical composition. Collectively, this research delineates a logical trajectory from composite materials to compositionally and structurally optimized polymers, culminating in a novel class of acid-stable, high-capacity, and kinetically robust adsorbents tailored for uranium recovery from highly acidic nuclear waste streams.
Keywords: Phosphonic acid-functionalized; Uranium; Adsorption; Strongly acidic waste; Soft template.

Speaker: Zhineng Wu (Lanzhou University)

8:52 AM Study on preparation of boron nitride-based adsorbents and their adsorption performance for uranium and iodine

Efficient adsorption of uranium (U) and iodine (I) is crucial for sustainable development of nuclear industry and human health. In order to develop high-performance adsorbents for efficient U and I adsorption from complex environment, boron nitride with great chemical and radiological stability was selected as adsorbent matrix and a series of adsorbents were developed. In this work, active hydroxyl and amino groups were introduced on the surface of hierarchically porous boron nitride (HPBN) as functionalization sites by radiation method, then boron nitride was furtherly functionalized by pyridine derivative functional groups. Prepared HPBN adsorbents exhibited ultrafast adsorption kinetic and excellent selectivity for U from radioactive sewage. For efficient capture iodine from vapor and solution, defect-engineered porous boron nitride areogels (BNA) were fabricated. The introdiction of N and B vacancies significantly increased the number of adsorption sites for I and enhanced the affinity of aerogels for I, resulting in excellent adsorption performance for I vapor as well as I in solution. In order to selectively extract U from seawater, the MOF with tunable pore structures was prepared by introducing diarylethene with photoisomerization property, then photoresponsive boron nitride aerogel (PBNA) was obtained by loading MOF in porous boron nitride aerogel. Photoresponsive boron nitride aerogels greatly increased the adsorption capacity of U by improving the dispersion of MOF, the selective adsorption of U was achieved by tuning the pore size to match that of U. This work provides new experimental idea for the modification of boron nitride adsorbents, and provides efficient adsorption materials for the rapid and selective adsorption of U and I.

Speaker: Peng Zhang (Lanzhou University)

9:14 AM Study on the Mechanism of Highly Selective Separation of Th(IV)/U(Ⅵ) Using COFs Designed for Precise Coordination Pockets

The alpha-radioactive alkaline effluent generated from the alkali washing course in the Purex Process represents a major challenge in downstream waste management. This necessitates the design of metal-organic frameworks (MOFs) or covalent organic frameworks (COFs) with tailored pore structures and functionalities for the highly selective capture of actinide ions under alkaline conditions. Given that radionuclides in such waste primarily exist as anionic complexes, this study employs the Williams reaction to post-synthesize COFs functionalized with quaternary ammonium (QA) groups of varying alkyl chain lengths. By controlling the grafting sites and density of these cationic groups, we effectively regulate the pore size distribution within the COFs. Twelve hierarchically porous QA-functionalized COFs were synthesized. We investigated the effects of QA group concentration and interlayer packing density on adsorption performance, revealing how pore volume effects and functional group content jointly influence the adsorption capacities for uranium and thorium (as a non-radioactive surrogate for plutonium) under alkaline conditions. The optimized material, COF-2QA-50, exhibits a high specific surface area, large pore volume, and outstanding adsorption performance, with static adsorption capacities of 568.7 mg/g for U(VI) and 508.8 mg/g for Th(IV). These highly crystalline COFs also show fast adsorption kinetics, reaching equilibrium within 30 minutes, and excellent reusability, retaining their original adsorption capacity over five consecutive adsorption-desorption cycles. Combined XPS and DFT analyses elucidated the adsorption mechanism, confirming the critical role of the balanced cavity structure and strategic positioning of QA groups in the effective capture of actinide radionuclides.

Speaker: zengyuan li

9:36 AM Integrated Spectro-Electrochemical Study of Technetium Redox Reactions and Ligand‑Dependent Speciation in Aqueous Media

Technetium 99 is a long-lived fission product whose environmental mobility is controlled by redox transformations between the highly soluble Tc(VII)O4− anion and low valent Tc(IV) species that exhibit strong sorption or precipitation behavior. Understanding the formation, stability, and interconversion of these species in complex aqueous environments is essential for reliable safety assessments of nuclear waste repositories, particularly under carbonate-rich or alkaline conditions representative of cementitious systems.
This work applies controlled potential electrochemistry, coupled with in situ UV vis, 99Tc nuclear magnetic resonance (NMR), and infrared spectroscopy (IR), to investigate Tc(VII) reduction pathways and ligand-dependent stabilization of low valent technetium species. Building on earlier carbonate studies, where carbonate was found to stabilize even lower Tc oxidation states.1 We systematically explore Tc(VII) reduction across a wide range of parameters. This includes carbonate concentrations, pH values, and Tc loadings. Distinct Tc(IV) and Tc(III) carbonate complexes are generated at defined potentials and identified by characteristic UV vis absorption bands. Newly observed 99Tc NMR resonances provide direct structural and electronic insight into these species, enabling refined mechanistic assignments for carbonate-mediated redox processes.
In addition, Tc(VII) reduction in strongly alkaline gluconate media is investigated by electrochemical methods to probe ligand-stabilized low valent Tc species relevant to organic-rich cement porewaters, since previous experiments have demonstrated the presence of low-valent gluconate complexes.2,3 Complementary background measurements in gluconate-only solutions allow unambiguous attribution of Tc-specific spectral features. These experiments establish a robust spectroelectrochemical baseline for identifying transient intermediates and quantifying their formation as a function of applied potential and ligand environment. These results will improve predictions of Tc mobility under repository-relevant conditions and support the development of more reliable long-term safety assessments for nuclear waste management.

Acknowledgements:
The authors acknowledge the German Federal Ministry of Research, Technology and Space and the German Federal Ministry for the Environment, Climate Action, Nature Conservation and Nuclear Safety for funding the NukSiFutur young investigator group TecRad (02NUK072) and the RULET project (02E12224B).

References:
1 Paquette, J. and Lawrence, W. E. Canadian Journal of Chemistry 63.9 (1985): 2369-2373.
2 Dardenne, K., et al. Inorganic Chemistry 60.16 (2021): 12285-12298.
3 Polly, R., et al. Inorganic Chemistry 64.11 (2025): 5412-5423.

Speaker: Mario Löw (Helmholtz-Zentrum Dresden-Rossendorf)

10:00 AM → 10:30 AM Coffee Break

10:30 AM → 12:00 PM Education: EDU 2

Conveners: Elena Macerata (Politecnico di Milano), Marko Štrok (Jožef Stefan Institute)

10:30 AM IAEA Approaches to Knowledge Transfer in Radioactive Waste Management

Effective knowledge transfer is essential for sustaining national nuclear programmes and ensuring the safe, secure and efficient deployment of nuclear technologies. The International Atomic Energy Agency (IAEA) supports its Member States in building and maintaining technical competencies through a comprehensive suite of digital platforms, training mechanisms and collaborative frameworks. These include face-to-face training courses and workshops, as well as online learning, fellowship programmes and schools on various nuclear-related topics.
A core component is the IAEA ´support of knowledge transfer and competence building represent portfolio of e learning modules Online Courses | International Atomic Energy Agency, which offer structured, accessible training on different topics, spanning from nuclear energy production, nuclear safety, nuclear analyses, nuclear fuel cycle, predisposal waste management, disposal solutions, decommissioning strategies and environmental remediation. These online courses complement national training programmes and help establish a consistent baseline of knowledge across diverse member state technical communities.
The development of technical documents, as e.g. IAEA Nuclear Energy Series (NE Series Publications advanced search | IAEA) documents supports Member States by offering methodologies, technology aligned approaches and internationally recognized lessons learnt and best practices for waste characterization, packaging, storage, treatment, disposal and remediation. These documents capture global experience and serve as key references for national frameworks, project planning and regulatory compliance.
Member States also benefit from Technical Cooperation (TC) projects Nuclear technology for development used safely, peacefully, securely | IAEA, which enable hands on capacity building, expert missions, training schools and procurement support tailored to national needs. IAEA supports also Member states with peer review services, as e.g. ARTEMIS or INIR missions.
Collaboration and peer learning are further enhanced through the Agency’s technical networks. The DISPONET network fosters the exchange of practical experience on low level radioactive waste disposal; the Underground Research Facility (URF) Network connects underground labs, dedicated to deep geological disposal; LABONET supports characterization and analytical laboratories; and ENVIRONET strengthens expertise on environmental remediation. These networks provide platforms for sharing lessons learned, developing harmonized approaches and advancing innovative solutions.
The Marie Sklodowska-Curie Fellowship Programme (MSCFP) aims to help increase the number of women in the nuclear field. Its goal is to inspire and encourage young women to pursue a career in the nuclear field, by providing highly motivated female students with scholarships for master’s programmes.
Looking ahead, the IAEA will continue to support global knowledge exchange through the conferences such as the International Conference on Radioactive Waste Management and Environmental Remediation, planned for November 2027, which plans to bring together technical experts, policy makers and operators to discuss emerging challenges and future directions.

Speaker: Dr Václava Havlová (International Atomic Energy Agency)

11:00 AM Utilizing Gap Analysis for Developing Undergraduate Radiochemistry Talent

The sustainability of nuclear science and technology depends on the development of a technically skilled workforce capable of supporting missions in energy, security, medicine, and environmental stewardship. Gap analyses conducted as part of US Department of Energy program across the nuclear enterprise have identified critical shortages in radiochemistry expertise, particularly at the technician and early career scientist levels. Addressing these talent and capability gaps requires educational programs that integrate fundamental radiochemical science with applied laboratory training. An undergraduate radiochemistry training initiative is being developed at the University of Nevada Las Vegas to directly respond to these radiochemistry talent needs.
Information derived from workforce development studies and sustained mission oriented research programs has been used to design a multidisciplinary undergraduate curriculum that integrates faculty and resources from the College of Sciences and the College of Engineering. The program emphasizes hands on laboratory experience in radioanalytical methods, actinide chemistry, nuclear measurements, radiation detection, and separation science. Students will participate in research projects that expose them to real world radiochemical challenges, including isotope production, environmental radioactivity, nuclear forensics, and advanced nuclear fuel cycle chemistry. This experiential learning approach strengthens theoretical understanding while providing practical technical competencies required for employment in nuclear laboratories and industry.
The educational model incorporates direct engagement with US national laboratory partners and research programs supported by the U.S. Department of Energy and the National Nuclear Security Administration. Student participation in collaborative research activities provides training in radiochemical techniques, analytical instrumentation, quality assurance protocols, and nuclear material handling. These experiences are designed to prepare graduates for multiple career pathways, including immediate entry into the workforce as radiochemical technicians at national laboratories or industrial facilities, as well as progression into graduate level education in nuclear chemistry, radiochemistry, and nuclear engineering.
The program also addresses broader educational objectives by increasing student awareness of nuclear science applications and strengthening recruitment into radiochemistry degree pathways. The integration of undergraduate research with national mission priorities demonstrates how academic institutions can serve as critical contributors to workforce development. The development of this undergraduate radiochemistry program illustrates how gap driven educational strategies can produce technically proficient personnel while simultaneously advancing research capabilities and sustaining national nuclear science infrastructure.

Speaker: Kenneth Czerwinski (University of Nevada, Las Vegas)

11:20 AM Modernizing Lab Preparation: Implementing Digital Interactive Scripts in a Physics Lab Course

In higher physics education, lab courses are an important part of the academic studies by providing hands-on practical experience and fostering essential technical and analytical skills. In this era of digital transformation, modernizing lab courses through digital integration is essential to meet evolving student expectations, support motivation and improve student’s preparation.

To address these needs, an online learning environment was designed to replace the script with digital material, allowing students to study at their own pace. The interactive structure allows students to choose the order of topics themselves creating individual learning paths. Different units cover the experimental procedures, an exercise to analyse example data and the necessary theory structured as interactive non-linear presentations. Here, after each slide with theoretical content, learners answer related questions to check their understanding. Wrong answers redirected them back to the theory slides. Afterwards they can independently select the next topic area. To avoid redundancy with previous lectures, the presentation incorporated a branching logic, that utilizes pre-testing. Students who correctly answer the questions can skip theory slides. Incorrect answers lead directly to the relevant theory. This individualized pacing respects the learner's pre-knowledge while ensuring all acquire the foundational understanding to begin the lab work. Furthermore, by bypassing theoretical slides students optimize their preparation time, ensuring that the workload represents the individual learning needs.

Qualitive evaluation of student feedback indicate a highly positive reception, with students enjoying the modernized lab preparation. From the tutor’s perspective during the experiments, student engagement with the course material increased, significantly reducing the need for verbal instructions. While these enhancements did not immediately translate into higher preparation quality, the results highlight a successful shift toward student autonomy and establish a solid foundation for future pedagogical refinements.

Speaker: Charlotte Fischer (Leibniz University Hannover)

11:40 AM Bringing nuclear science to master students from non-nuclear fields. A case study of ENEN2plus 14C workshop

Nuclear and radioanalytical methods have many applications in various disciplines and multidisciplinary research. As a practitioners of these methods, we meet with students and researchers from scientific disciplines where the word "nuclear" is not common. In this paper we would like to share our experiences, what worked and what did not work, from a specialized workshop where ultra-sensitive technique Accelerator mass spectrometry (AMS) was presented to university students in master programs from non-nuclear fields. The workshop was organized by Nuclear Physics Institute of the Czech Academy of Sciences under the umbrella of the ENEN2plus project. This initiative in currently the largest education and training integrated effort in the nuclear field. Funded by the European Union, ENEN2plus has been supporting development of human resources for power and non-power nuclear applications, attracting young talents, and development of the career of workers in academia, industries, technical safety organizations and regulators [1].

The ENEN2plus 14C workshop targeted on measurement of radioactive $^{14}$C at low-level for applications in environmental monitoring, radiocarbon dating, carbon cycle studies, differentiation between fossil carbon and recent carbon (biofuels). The applicants submitted short proposal based on presented guidelines. After evaluation of the proposals, the selected candidates provided their samples to the Czech Radiocarbon Laboratory (CRL).

The 5-day workshop included theoretical lectures, massive hands-on training in sample preparation in the laboratory, samples measurement by AMS, data evaluation, calculation $^{14}$C activities and drafting conclusions. Thanks to that, participants got complete information how the sample and measurement is handled prior the final result is provided to customers. The program was enriched by excursions.

Acknowledgement: The work was supported by the European Union through the ENEN2plus project.

[1] G. L. Pavel, C. Pesznyak, F. J. Elorza Tenreiro, J. Starflinger, L. Cizelj, W. Ambrosini (2024) The ENEN’s role in shaping the European nuclear education. Nuclear Engineering and Design 420:112999.
https://doi.org/10.1016/j.nucengdes.2024.112999.

Speaker: Dr Jan Kameník (Nuclear Physics Institute of the Czech Academy of Sciences)

10:30 AM → 12:00 PM Nuclear Analytical Methods: NAM 3

Conveners: Jiří Janda (-), Zsolt Révay (Technische Universität München - FRM II)

10:30 AM Radioanalytical method for the separation of 225Ac for bioassay monitoring

At Los Alamos National Laboratory (LANL), the in vitro bioassay program has been in place for several decades and currently monitors several thousand workers with occupational risk of radionuclide intake. The program includes the analysis of plutonium uranium, americium, and tritium in urine samples provided by workers. The suite of analyses will be extended with 225Ac analysis in the near future. Workers involved in the future production of pharmaceutical 225Ac will be monitored using this new capability.
The 225Ac is produced by high energy proton irradiation of high purity 232Th at Los Alamos Neutron Science Center (LANSCE) at LANL. The initial product contains a wide range of isotopes besides 225Ac, e.g., various isotopes of radium, thorium and rare earth elements. A relatively rapid radiochemical separation procedure to be used in emergency situations was developed based on ion exchange and extraction chromatography for the 225Ac analysis. The 4-column procedure removes interfering elements, such as thorium, radium, rare earth elements, iron, calcium and other urine constituents using iron(II) hydroxide co-precipitation, anion exchange, cation exchange and extraction chromatography. The 225Ac assay analysis is performed by isotope dilution alpha spectrometry using 227Ac as tracer. For the 225As assay calculations, the significant decay of the measurand during the measurement is accounted for. The procedure has been validated using urine samples spiked with 229Th certified reference material that was in secular equilibrium with its progeny, 225Ac.

Speaker: Zsuzsanna Macsik

10:48 AM Isotopic techniques to trace the authenticity of beef from a terroir in the Brazilian Cerrado biome

Brazil holds a prominent position in the global beef cattle industry, being currently the largest producer and exporter, and possessing the largest commercial cattle herd. This leading role is the result of investments in genetic improvement, advances in animal nutrition, and modernization of production systems. However, the sector growth has not been accompanied by equivalent advances in traceability systems throughout the production chain, since a significant portion of slaughtering still occurs outside formal inspection systems. The growing demand from the international market for traceable, safe, sustainable foods with guaranteed origin reinforces the need to develop methodologies capable of ensuring the authenticity of beef. In this context, approaches based on intrinsic food characteristics, such as elemental composition, have emerged as promising tools for authenticity and traceability. This study aimed to develop models capable of differentiating beef originating from a terroir that produces meat sustainably and with high quality standards in the Brazilian Cerrado biome. The elemental composition of the samples was determined by neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICP-MS). Classification models were built using Multilayer Perceptron (MLP), Random Forest (RF), Support Vector Machine (SVM), Classification and Regression Trees (CART), and Naïve Bayes (NB). The results demonstrated that the integration of multi-element data and chemometric tools allows the construction of robust models for authenticating the origin of beef, contributing to fraud prevention and strengthening reliability in the Brazilian beef production chain.

Speaker: Mr Thales Nagayoshi Alves Kornfeld (Nuclear Energy Center for Agriculture, University of São Paulo)

11:06 AM Energy and position determination of alpha and beta particles with a Timepix detector chip

Targeted alpha radionuclide therapy is very promising in the treatment of metastasised tumours. There are several promising radioisotopes in this therapy; 212Pb, 211At and 225Ac. For the latter there is a decay chain having several daughter radionuclides that also emit alpha radiation making it a very potent treatment. One of the key questions in QC is the bonding percentage of the radioisotope to the targeting vector.
The determination of this percentage in often established using TLC of HPLC in combination with a typical gamma measurement, usually of a daughter nuclide which requires equilibrium.

Over the years we have developed and further perfected a method to directly look at the alphas and even beta emission using a Timepix detector chip. The Timepix detector, developed by CERN, is a 256 x 256 pixilated detector chip with 55 µm size pixels with an energy determination per pixel. When a charged particle like an alpha hits the chip it will deposit its energy and distribute this over several pixels, typically 4 to 20. From this event the total energy can be calculated as well as the sub-pixel position of the alpha. With this we are able to measure a localised alpha spectrum and beta energy distribution giving more direct information about the sample, even when not in equilibrium, compared to gamma spectroscopy only.

We will present typical examples and show the potential of this method but also the limitation.

Speaker: Jeroen Plomp (Delft University of Technology)

11:24 AM Comparison of Neutron activation analysis (NAA) with a digestion/ICP-MS protocol for the analysis of lichens in two mining-affected areas in Northern Ontario (Canada).

Lichens are widely used as biomonitors of atmospheric deposition because they may accumulate nutrients and potentially toxic elements (PTEs) directly from wet and dry deposition. Reliable and routine analytical methods requiring minimal preparation are desirable for routine multi-element analysis for assessing environmental baselines, stress or recovery, especially considering potential future industrial developments like new mines or small modular reactor installation (SMRs) in remote regions of Canada.
This study evaluates neutron activation analysis (NAA) as a primary analytical method on lichens, and was compared with a reverse-aqua-regia/HF digestion followed by ICP-MS analysis in two independent laboratories. Three fruticose lichens were analyzed: Stereocaulon spp., collected in the vicinity of an industrial area of Sudbury (Ontario, Canada), an area with over 125 years of base metal mining and ore-processing activity; Cladonia (section Cladina) spp. collected from a nearby unimpacted site, and the certified reference material (CRM) lichen Pseudevernia furfuracea (BCR 482). The NAA protocol targeted stable major elements and selected trace elements PTEs.
NAA routinely quantified 22 elements in all three samples. The NAA results were generally consistent with the certified and indicative values of the CRM, with the exception of Co. The digestion/ICP-MS protocol and NAA showed strong agreement for the CRM (R2 = 0.986, slope = 1.008 for all detected elements except for Co). For the field samples, the results for Stereocaulon spp. exhibited a strong agreement between methods for all detected elements
(R² = 0.980; slope = 0.9504), whereas the results from the low-metal Cladonia spp. exhibited a strong relationship (R² > 0.942) between all detected elements for both methods, but a lower slope (= 0.726), suggestive of a low recovery by the digestion/ICP-MS protocol, relative to NAA. For the latter sample, the concentrations of many trace elements and PTEs were not statistically significant between analysis techniques, indicating that that either method provides a reliable estimator of minor and trace element contamination.
Finally, the NAA analysis scheme was evaluated as a stand-alone technique for the determination of selected major, minor and PTEs in the area of Elliot Lake (Ontario, Canada, approximately 120 km west of Sudbury). The uranium mining and milling operations that impacted the Elliot Lake area for nearly 40 years until the 1990s, are now closed and in state of care and maintenance. Results from three sampling campaigns (2020 August, 2021 August and October) are presented. Overall, NAA is presented as a robust primary method for multi-element lichen analysis, requiring minimal sample preparation while providing users with high accuracy data.

Speaker: Dr Francois Caron (Royal Military College of Canada, Kingston)

11:42 AM Overcoming Isobaric Interferences in ³⁶Cl Analysis: An Optimized ICP-MS/MS Strategy, Improved ³⁶Cl Determination in Nuclear and Environmental Samples by ICP-MS/MS

Chlorine-36 (³⁶Cl) is a long-lived pure β-emitter (T₁/₂ = 3.01 × 10⁵ y) produced mainly by neutron activation of ³⁵Cl impurities in nuclear fuels and reactor building materials[1]. ³⁶Cl is found in the environment at ultra-trace levels (³⁶Cl/Cl = 10⁻¹⁵–10⁻¹³ at·at⁻¹)[2]. Due to chlorine high volatility and mobility, the reported animals and plants samples activities in 36Cl are 0.026 – 1.201mBq.kg-1 in animal and plant samples near fuel reprocessing plants [3] and 0.0021 – 0.54 Bq.L-1 in waters around waste storage sites. Traditional quantification relies on Liquid Scintillation (LSC) or Accelerator Mass Spectrometry (AMS) with limits of detection (LOD) in the range of 10-12g.g-1 and 10-15g.g-1 (36Cl/35Cl) respectively.
Even if the AMS is the only method fully compatible with environmental levels, this device is limited due to cost and accessibility.

This study explores a new methodology, applied to both aqueous and solid matrices, based on a pyrolysis step with the Pyrolyser® Gen IV (Raddec) to efficiently extract chlorine from complex matrices, followed by a purification step using CL resin® (Triskem International) and a measurement step using an ICP-MS/MS (8900 Agilent ®).The extraction and the purification processes were optimized to allow treatment of large sample volumes (up to 2 L), thereby improving analyte reconcentration and detection limits, while replacing sulphur-bearing reagents, that would otherwise introduce isobaric interference from ³⁶S⁺, with water, and potassium cyanate as alternatives.

Major analytical challenges for ³⁶Cl determination by ICP-MS/MS include its very low ionisation efficiency (<1% due to the first ionisation potential of 12.967 eV) and isobaric interferences from ³⁶S⁺ and ³⁶Ar⁺. To overcome these limitations, an innovative use of collision/reaction cell gases was implemented. The addition of C₂H₂ promoted the selective formation of C₂HS⁺ with sulphur, while ³⁶Cl⁺ remained unaffected[4]. Simultaneously, N₂ facilitated charge transfer reactions with ³⁶Ar⁺, further reducing background signals. Complementary plasma tuning with He–Ar mixtures provided a significant sensitivity enhancement, resulting in a 36Cl limit of detection of 3.29 × 10⁻¹¹ g·g⁻1 (4.00 x 10-2 Bq.g-1) in aqueous solutions containing 0.01% HCl and H₂SO₄.
Overall, the developed protocol outperforms LSC and approaches AMS performance, offering a practical, cost-effective, and more widely accessible alternative for ³⁶Cl quantification. The method is particularly well suited for reactor construction materials and environmental samples at activity levels expected near nuclear facilities.

Speaker: Amayes Gaston-Bellegarde (Autorité de surêté nucléaire et radioprotection (ASNR))

12:00 PM → 1:00 PM Lunch

1:00 PM → 6:00 PM Socials: Conference Trip

7:00 PM → 10:00 PM Socials: Conference Dinner

Thu, May 14

8:30 AM → 10:00 AM Nuclear Fuel Cycle: NFC 4

Conveners: Christian Schreinemachers (Forschungszentrum Jülich GmbH, Institute of Fusion Energy and Nuclear Waste Management, IFN-2: Nuclear Waste Management), Michael Ojovan (The University of Sheffield)

8:30 AM Competitive sorption effects of Al on the retardation of Eu by quartz and K-feldspar: Experimental and mechanistic modelling insights

The adsorption of radionuclides (RNs) onto mineral surfaces is a key retardation mechanism and plays a critical role in the long-term safety assessment of radioactive waste repositories. While numerous studies have investigated the sorption behavior of trivalent actinides (e.g. Am, Cu) and lanthanides (e.g. Eu, Y) on various minerals, most experiments rely on geochemically simplified systems, typically in binary configurations involving single minerals and single sorbing species. Natural systems, however, are considerably more complex, with competitive sorption, bulk and surface precipitation, incorporation, and co precipitation processes all influencing RN retardation.

In this study, we examine the competitive sorption of Eu (a chemical analogue for trivalent actinides) and Al onto quartz using a combination of batch and column experiments supported by mechanistic surface complexation modeling (SCM). Aluminum, an abundant component in natural groundwater and porewater, may compete with RNs for sorption sites. In addition, due to its low solubility at near neutral pH, Al may undergo surface precipitation, altering mineral surface charge and modifying sorption behavior.

Batch experiments were performed under varying geochemical conditions, including pH, ionic strength, and initial Al and Eu concentrations. The results show that Al sorption onto quartz arises at lower pH compared to Eu, with sorption edges at approximately pH 4.5 for Al and pH 5.5 for Eu (50% sorbed). In the presence of Al, Eu sorption onto quartz is significantly reduced. Batch sorption data is used for SCM calibration via inverse modeling. These models are then validated using experimental data from column experiments to assess the applicability, advantages, and limitations of derived parameters. In addition, column experiments with K‑feldspar are planned and will be evaluated using SCM to further examine competing sorption effects. Ongoing work focuses on further model development. First modelling outcomes, together with initial assessments of the applicability, strengths and limitations of the emerging parameter set will be presented.

These investigations contribute to improving previous modelling approaches in which competitive Al sorption may have influenced radionuclide behavior. More broadly, the results highlight the importance of understanding geochemical surface reactions to enhance the reliability of long term safety assessments for radioactive waste repositories.

Speaker: Dr Susan Britz (GRS gGmbH)

9:00 AM Pyrite solubility and its capacity to immobilize ⁹⁹Tc in metabolite‑rich environments

Technetium-99 ($^{99}$Tc) is a long-lived fission product (t½ = 2.13 × 10⁵ a) with high yield (~6%) that poses environmental concerns due to its complex redox chemistry.[1] Under oxic conditions, it exists as the highly mobile pertechnetate anion ($\mathrm{TcO_4^-}$), whereas under reducing conditions, $\mathrm{Tc^{IV}}$ is less mobile and readily sorbs onto mineral surfaces or precipitates as $\mathrm{TcO_2 \cdot nH_2O}$ or $\mathrm{TcS_2}$.[1], [2]
The deep geological repository is considered the best practice for the long−term isolation of radioactive material from the environment. It follows the multi-barrier concept where bentonite clay is used as backfill material. Pyrite ($\mathrm{Fe^{II}S_2}$) is one of the accessory minerals found in the bentonite clay,[3] where also indigenous bacteria grow, producing metabolites. In the worst-case scenario of the safety assessment for such repository, Tc might be released in the surrounding environment. It is known that $\mathrm{Tc^{VII}}$ can be retained by pyrite in absence of any metabolites due to reductive immobilization. Tc retention mechanisms involve inner-sphere complexation of $\mathrm{Tc^{IV}\text{-}Tc^{IV}}$ dimers onto hematite at pH 6, and $\mathrm{Tc^{IV}}$ incorporation into magnetite via $\mathrm{Fe^{III}}$ substitution ≥ pH 10.[4] However, this Tc immobilization by pyrite can be influenced in presence of metabolites.
In this study, the effect of metabolites (acetate, succinate and DFOB) on pyrite solubility was studied using inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC). The $^{99}$Tc immobilization was investigated using liquid scintillation counting (LSC), nuclear magnetic resonance (NMR), and Tc K-edge X-ray absorption spectroscopy (XAS). Results showed the increase in pyrite solubility in presence of metabolites, especially with DFOB. The kinetics of Tc immobilization by pyrite were slightly slower in the presence of acetate and succinate. In contrast, DFOB significantly decreased the quantitative removal of $^{99}$Tc by pyrite, to a maximum of 25%. The XAS investigation showed the presence of $\mathrm{Tc^{IV}}$ in all the Tc-containing solid samples and different immobilization mechanism as a function of metabolite and pH. NMR experiments showed the presence of an aqueous Tc-DFOB complex.
Work in progress focuses on studying $^{99}$Tc migration in the environment by column experiments, and the determination of the Tc complexation constants with metabolites by solvent extraction method[5] and isothermal titration calorimetry (ITC).

Acknowledgements
The authors acknowledge the German Federal Ministry of Research, Technology and Space (BMFTR) for the financial support of the NukSiFutur young investigator group TecRad (02NUK072). The authors express their gratitude to Prof. Gareth Law and Dr. Rohan Jain for the support of this work.

Speaker: Mr Vijay Kumar Saini (Helmholtz-Zentrum Dresden-Rossendorf e.V.)

9:20 AM Leaching of irradiated MOX fuel under repository-relevant conditions: Impacts on microstructure

In several countries, direct disposal of spent nuclear fuel (SNF) in a deep geological repository (DGR) is the preferred waste management option. Understanding SNF corrosion if the waste canister is breached and the fuel comes into contact with groundwater is required to evaluate the long-term safety of a DGR over an assessment timeframe of up to one million years. While various studies have addressed this issue in the past, some open questions remain with respect to the processes contributing to the radiolytic corrosion of SNF in a reducing repository environment. Furthermore, little research has been conducted on the corrosion behaviour of irradiated mixed oxide (MOX) fuels, and only limited knowledge exists on the impact of corrosion on the microstructure of SNFs.

In order to investigate the impact of environmental conditions on SNF corrosion, three irradiated Zircaloy-4 clad MOX fuel rod segments with burn-ups ranging from 29 GWd/tHM to 52 GWd/tHM were leached in bicarbonate water at circumneutral pH and in synthetic cementitious water at a pH of 13.7(2), under a reducing atmosphere (4 vol% H₂ in Ar at 40 bar pressure) for approximately 3.5 years. Following the leaching phase, the fuel rod segments were examined by scanning electron microscopy (SEM) and fragments of these leached segments were analysed by energy-dispersive X-ray spectroscopy (EDS). The post-leaching analyses revealed that the exposure to the diverse environmental conditions affected the SNF microstructure differently. A deposit containing several leachate constituents (e.g., potassium, sodium, and calcium), as well as zirconium and titanium, was identified on surfaces exposed to the synthetic cementitious water [1]. The presence of titanium in the surface deposits indicates that the titanium-coated stainless steel autoclave liners corroded during the leaching experiment. In contrast, the surface of fuel segments exposed to bicarbonate water showed significantly less amounts of surface deposits; in these deposits, no titanium could be detected by EDS.

This contribution presents initial findings of the post-leaching characterisation of the fuel segments and discusses their implications for the corrosion behaviour of SNF under repository-relevant conditions.

1. C. Schreinemachers, G. Leinders, J. Van Eyken et al. "Characterisation of high burnup spent mixed oxide fuel after leaching at hyperalkaline pH in a reducing environment". MRS Advances 9, 351-356 (2024). https://doi.org/10.1557/s43580-024-00791-7

Speaker: Dr Christian Schreinemachers (Forschungszentrum Jülich GmbH, Institute of Fusion Energy and Nuclear Waste Management, IFN-2: Nuclear Waste Management)

9:40 AM Competitive Sorption of Trivalent Metals on Hematite: Relevance for Actinide Retention in Repository Environments

Understanding the mechanisms governing radionuclide transport is essential for assessing the long-term safety of deep geological repositories for radioactive waste. In many countries, including Germany, crystalline rock formations are considered potential host rocks due to their low permeability and structural stability. Radionuclide retention in such systems relies strongly on geochemical interactions at the mineral–water interface, particularly sorption processes. Aluminosilicate minerals, such as feldspars and mica, play a key role in these interactions; however, variations in mineralogy and surface reactivity introduce additional complexity. A potentially critical but insufficiently understood factor is the role of dissolved Al³⁺, which can re-adsorb onto mineral surfaces, modify sorption sites, and compete with radionuclides.
To isolate and investigate the influence of Al³⁺ on mineral surfaces, this study employs hematite (α-Fe₂O₃) as an aluminum-free model system. Batch sorption experiments (100 µM Al³⁺, 0.1 M NaCl, S/L = 3 g L⁻¹) revealed pH-dependent Al³⁺ retention, with sorption occurring prior to gibbsite precipitation (Al(OH)₃). At lower pH, zeta potential measurements indicated electrostatic interactions and suggested the formation of inner-sphere surface complexes. Above pH 10, Al³⁺ retention decreased due to the formation of the negatively charged [Al(OH)₄]⁻ complex.
Because direct spectroscopic investigation of Al³⁺ surface complexes is challenging, Ga³⁺ was used as a chemically similar spectroscopic proxy. Ga³⁺ is also of growing technological relevance, particularly in the semiconductor and renewable energy sectors. Sorption experiments with Ga³⁺ (100 µM, 0.1 M NaCl, S/L = 3 g L⁻¹) showed comparable pH-dependent behavior, with a low sorption edge at pH 2.5, and decreased retention at higher pH due to [Ga(OH)₄]⁻ formation. Precipitation experiments confirmed the formation of insoluble Ga(OH)₃ within the pH range of 4 to 8, i.e. starting at higher pH than the sorption processes. X-ray absorption spectroscopy provided molecular-scale insights into Ga³⁺ binding environments at the hematite surface, indicating the formation of only one Ga surface complex over the whole pH range.
Surface complexation modeling was performed for both Al³⁺ and Ga³⁺ sorption on hematite. The models reproduced the experimental sorption data well and yielded consistent intrinsic stability constants for inner-sphere surface complexes, with log K values of −1.20 ± 0.06 for Ga³⁺ and 0.22 ± 0.11 for Al³⁺.
Additionally, the influence of Al³⁺ concentration on Eu³⁺ sorption onto hematite was investigated as an analogue for trivalent actinides and lanthanides relevant to repository safety. Eu³⁺ sorption onto hematite exhibited a sorption edge at pH 5.5, consistent with previous studies. Competitive sorption experiments demonstrated that Al³⁺ did not significantly influence Eu³⁺ retention, except for a minor enhancement of Eu³⁺ retention at low pH, indicating limited competition under environmentally relevant conditions.
Overall, this study advances the molecular-level understanding of metal(loid) sorption processes at oxide surfaces. By combining batch experiments, electrokinetic measurements, spectroscopic analysis, and surface complexation modeling, the results support the development of more robust surface complexation models and improve confidence in predictive radionuclide transport simulations. These findings have broader implications for repository safety assessments, environmental geochemistry, and contaminant retention processes.

Speaker: Stephan Hilpmann (Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology)

8:30 AM → 10:00 AM Nuclear Analytical Methods: NAM 4

Conveners: Jan Kučera (Nuclear Physics Institute of the Czech Academy of Sciences), Zsuzsanna Macsik

8:30 AM Radioanalytical Chemistry for In-situ and On-line Determination of Radionuclides

In the nuclear fuel cycle, especially reprocessing of spent nuclear fuel, besides the uranium and plutonium, the main fission products and minor actinides such as 129I, 99Tc, 237Np, 241Am and their chemical species are needed to be monitored to precise control the separation process of key components. In the operation of nuclear facilities, such as nuclear power plants, the discharges of radionuclides in the liquid and atmospheric effluents require to be monitored for environmental safety. The conventional manual analytical methods are difficult to match precise and immediate control of the pathway of key radionuclides in these processes due to a long analytical time and delayed information feedback. Rapid, automated, in-line, even in-situ analytical methods are highly appreciated for these purposes.
This work presents the efforts in China to achieving an online and in-situ analysis of radionuclides in reprocessing process and influents from nuclear facilities nuclear power plants and medical radioisotope production laboratories. These efforts include synthesis and production of various separation materials for specific separation of different radionuclides from various media including atmosphere, acidic and alkaline effluent, as well as scintillation resin for direct separation of target radionuclides for direct measurement by scintillation counter; establishment of various separation methods specific separation of target radionuclides from complicated matrices and sequential separation of a series radionuclides from the same sample; design and establish separation system based on flow injection concept to fulfil automated separation of radionuclides; integrate detection and control systems with automated separation and scintillation separation material to achieving automated, on-line, even in-situ determination of radionuclides.
A few examples will be presented to demonstrate these achievements, such as in-situ monitoring 55Fe and 63Ni in liquid effluent, on-line and sequential determination of Pu, Np and Am in solution from spent nuclear fuel reprocessing.

Speaker: Xiaolin Hou (Lanzhou University)

9:00 AM A simplified and robust method for the non-radiometric determination of Tc-99 in spent ion exchange resins

Radiological characterisation is a crucial step in the management of radioactive waste emerging from both operation and dismantling of nuclear facilities. In this context, the quantification of difficult-to-measure radionuclides in complex sample matrices proves especially laborious. Spent ion exchange resins (SIERs) represent one of the most challenging ones, due to the vast radionuclide content, both in terms of type and quantity, with which they can be contaminated. As a consequence, radiometric methods for the characterization of SIERs need to cope with an extremely wide spectrum of interferents, resulting in development and validation difficulties. By contrast, the use of non-radiometric analytical techniques appears promising to provide more robust, versatile and faster quantifications in such complex matrices, thanks to a more limited set of interferents to be considered. The present work, carried out in the framework of the EURAD-2 partnership, Work Package – WP ICARUS, aimed at developing an analytical protocol for the non-radiometric determination of Tc-99 in SIERs. Coherently with the goals of the WP, the developed method prioritized simplicity, cost-effectiveness and sample throughput, but without sacrificing detection limits (DL). To improve applicability, the method is based on commonly available instrumentation, specifically single-quadrupole ICP-MS.

To develop the method, surrogate SIERs batches were prepared employing a mixed bed of nuclear-grade ion exchange resins, loaded with typical elements associated to steel erosion/corrosion and soluble poisons (Fe, Cr, Mn, Ni, B), isobaric and polyatomic interferents (Co, Mo, V, Zn, and Ru) and a known amount of Tc-99 tracer. Radiochemical yield of Tc-99 after each manipulation was determined via liquid scintillation counting, while the decontamination from matrix elements and spectrometric interferents was monitored by ICP-MS.

The method foresees a microwave-assisted acid digestion, a Fe(OH)$_{3}$ co-precipitation and ion exchange chromatography; the analyte solution is finally analysed by ICP-MS. After chemical purification, most matrix constituents were abated by a factor ≈10$^{3}$, with a chemical yield for Tc-99 of ≈100%. Decontamination factors for Ru and Co were >10$^{4}$; much lower removal of Mo was instead achieved. A systematic screening of the ICP-MS measurement bias induced by these three interferents indicated that the major effect is produced by the Ru-99 isobar, with Mo and Co polyatomics producing much less intense signals at mass 99. Interference from V and Zn was verified to be negligible, also when present at high concentrations. A specifically developed cross-calibration protocol allowed to reliably subtract the contribution of residual interferents from mass 99, resulting in a typical measurement bias for Tc-99 <5%.

Additional optional purification and concentration steps were also explored to further improve the DL of the method, which was lowered to <10 Bq/g. Next activities will involve testing the method on real waste samples as part of an intercomparison exercise organized within the WP ICARUS.
EURAD-2 is co-funded by the European Union under Grant Agreement n° 101166718.

Speaker: Dr Gabriele Magugliani (Politecnico di Milano)

9:20 AM Novel HCl‑free analytical method using cation‑exchange resin for highly selective determination of ¹¹³ᵐCd

We developed a simple and HCl-free radiochemical separation method for ¹¹³ᵐCd in high salt liquid samples using highly acidic cation-exchange chromatography with sodium thiosulfate as the eluent, coupled with pretreatment on an Empore™ chelate disk. The method’s applicability to ALPS-treated water (the water that contains radioactive materials Fukushima Daiichi Nuclear Power Station, and has been purified and treated until it satisfies safety standards for all radioactive materials other than tritium) was evaluated. Tests with synthetic samples showed high recovery of ¹¹³ᵐCd (90 ± 2.6%, n = 6) and effective separation from major interfering radionuclides, including ⁶⁰Co, ¹³⁷Cs, ⁹⁰Sr, ⁵⁹,⁶³Ni, ⁶⁵Zn, ⁹⁰Y, ¹²⁹I, ¹⁰⁶Ru, and ¹²⁵Sb, achieving typical decontamination factors of 10⁴–10⁶. The method detection limit, determined by liquid scintillation counting, is 0.2 Bq/L. Although quantification could not be validated due to the lack of available ¹¹³ᵐCd standards, the method is demonstrated to be sufficiently sensitive to monitor ¹¹³ᵐCd in ALPS-treated water whether its activity exceeds its regulatory clearance limit (40 Bq/L). The approach is also applicable to environmental water samples, providing a straightforward tool for monitoring and assessing environmental ¹¹³ᵐCd contamination.

Speaker: Van-Khoai Do (Japan Atomic Energy Agency)

9:40 AM Work Package 5 – ICARUS within the EURAD-2 programme: Innovative ChARacterization techniques for large volUmeS

The work package ICARUS (Innovative ChARacterization techniques for large volUmeS) is carried out in the framework of the EURAD-2 partnership. It aims at developing, optimizing and harmonizing innovative techniques for the characterization of radiological, physical and chemical properties in large volumes of low/intermediate-level mixed waste.
The work is being carried out over a period of 5 years by 29 organizations from 17 countries with complementary and innovation-based approaches under relevant industrial scenarios. A comprehensive state-of-the-art was performed to identify the most promising characterization techniques. The work programme is organized in 5 tasks: task 1 for the management of the WP, with focus on coordination, monitoring, dissemination, and quality assurance; task 2 for the knowledge management, including knowledge capture, education, training, and mobility actions; task 3 on Non-Destructive Techniques (NDT) aimed at determining radiological (gamma and neutron), physical (e.g. density, water content, heterogeneity) and chemical (e.g. alkali silica reactions in concrete) properties of large packages; task 4 on Destructive Techniques (DT) for optimized radiochemical analysis of long-lived Difficult To Measure (DTM) radionuclides; task 5 on Scaling Factors (SF) for improving accuracy, uncertainty, and reliability of the SF approach to estimate DTM radionuclides in raw mixed waste. Some use cases are being investigated to meet the needs of end users and waste management organizations.
In particular, task 4 aims at developing rapid and effective radiochemical methods coupled with radiometric or non-radiometric techniques to measure DTM radionuclides in complex sample matrices, such as alloys, metals, concrete, graphite, and ion exchange resins. The selected radionuclides may lack of reliable analytical methods (Se-79, Zr-93, Pd-107), or the available methods are excessively time consuming (C-14, Cl-36, Tc-99) or difficult to be standardized (Ca-41, Mo-93, Cs-135). An anticipation of some methods in a more mature stage of development will be presented. During the project, the developed methods will be validated through intercomparison exercises organized with ICARUS partners, end users and stakeholders.

EURAD-2 is co-funded by the European Union under Grant Agreement n°101166718.

Speaker: Eros Mossini (Politecnico di Milano)

10:00 AM → 10:30 AM Coffee Break

10:30 AM → 12:00 PM Environmental Radioactivity: RER 3

Conveners: Claudia Landstetter (AGES GmbH), Sebastian Fichter (Helmholtz-Zentrum Dresden-Rossendorf)

10:30 AM Tc soil to plant uptake from pot experiments to imaging at the nanoscale

The present work investigates Tc uptake from several standardized soils (RefeSol) into wheat, potatoes, carrots and peas. Experiments were performed in batches, columns and lysimeter experiments. Transfer factors and plant availability were obtained by sequential extraction. In order to understanding the plant uptake on a cellular level, the radionuclide distribution was imaged by mass spectrometry within the cellular structures of plants at varying concentrations. In a first step, plants of Daucus carota and Pisum sativum labelled with iodine and rhenium were examined, at concentrations in the range of 10 mM. Cross sections of several plant parts were imaged by secondary ion mass spectrometry (SIMS) after cryogenation in order to preserve cell structure. In a second step, the distribution of T-99c in the two plant species was determined. For radiological reasons, a concentration three orders of magnitude lower was used, rendering measurements with SIMS impossible. Therefore, resonant laser secondary neutral mass spectrometry (rL-SNMS) was used to image Tc-99 with suppression of molecular isobaric interferences. The measurement of only about 1E10 atoms of Tc-99 is demonstrated and the distribution of Tc-99 within a single epidermal cell is imaged.

Speaker: Clemens Walther (Universität Hannover, IRS)

10:48 AM Influence of soil amendment with fly ash from Coal-Fired Power Plant on the transfer of naturally occurring radionuclides to wheat

Fly ash is a by-product from Coal-Fired Power Plants (CFPPs), which is a NORM (Naturally Occurring Radioactive Material) industry, and presents enhanced activity concentration of 226Ra, 232Th and 210Po, among other naturally occurring radionuclides. Formerly considered as waste, it is considered a by-product which can be used in different ways, such as additive to cement production or soil amendment in agriculture. The latter may imply a radiological hazard due to the introduction of these radionuclides into the food chain pathway. In order to assess its importance, laboratory experiments under controlled conditions were carried out by amending soil used for wheat cultivation with a known amount of fly ash. Then, wheat plantlets were cultivated under laboratory conditions until the two-leaf stage using original soil as control and amended soil. Soil-to-plant transfer factors showed a general decrease in radionuclide transfer when using amended soil.

Speaker: Francisco Javier Guillén Gerada (LARUEX, University of Extremadura)

11:06 AM Distribution of Natural Radionuclides and Dose Assessment in Phosphate-Fertilized Soils

Phosphate fertilizers are widely used in Uruguay due to the natural phosphorus deficiency of most agricultural soils. These fertilizers contain naturally occurring radionuclides which may represent a potential source of radiological exposure for the population. This study aims to evaluate the impact of phosphate fertilization on the distribution of natural radionuclides in horticultural systems and to estimate the associated radiation doses under different exposure scenarios.
Pot experiments were conducted using soil from two regions with contrasting characteristics: Canelones, an intensively cultivated agricultural area, and Rocha, a coastal zone without previous farming activity. Three phosphate fertilizers (phosphate rock, NPK, and triple superphosphate), an organic fertilizer, and an unfertilized control were applied. Spinach (Spinacia oleracea) was cultivated for three months under controlled irrigation conditions. After harvesting, soil, leachate water, and plant biomass samples were collected for analysis.
Activity concentrations of radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K, ²¹⁰Po, ²³⁸U, and ²³⁴U) were determined by high-resolution gamma spectrometry and alpha spectrometry using standardized procedures and certified reference materials. Soil-to-plant transfer factors and concentration ratios between solid and aqueous phases were calculated to assess radionuclide mobility.
Experimental results indicated that, under the tested conditions, differences in radionuclide concentrations between fertilized and control soils were not statistically significant. Consequently, an indirect approach was adopted for dose assessment, estimating soil activity concentrations from fertilizer radionuclide contents and application rates, assuming homogeneous mixing within the topsoil layer.
Radiological risk assessment was performed using the RESRAD-ONSITE and RESRAD-OFFSITE codes for representative rural and urban exposure scenarios. For phosphate rock fertilization, the maximum total effective dose from all radionuclides and all exposure pathways in rural scenarios was estimated at 2.32 × 10⁻³ mSv·year⁻¹, occurring at 1000 years, with external gamma exposure as the dominant pathway and ²²⁶Ra providing the largest contribution to external dose. For triple superphosphate fertilization, the maximum total effective dose was estimated at 2.057 × 10⁻³ mSv·year⁻¹, also occurring at 1000 years, with ²²⁶Ra again being the main contributor to external exposure. In contrast, for NPK fertilization, the maximum total dose was 7.8 × 10⁻⁵ mSv·year⁻¹, occurring at time zero, with ⁴⁰K representing the largest contribution to the total dose.
In all cases, the estimated doses remained well below recommended radiological protection limits, indicating a low radiological impact associated with routine phosphate fertilizer use in Uruguay. This study represents the first comprehensive radiological assessment of phosphate fertilization in the country and establishes a baseline for future investigations, contributing to regional knowledge on natural radionuclide behavior in agricultural systems.

Speaker: Ana Noguera (Centro Universitario Regional del Este, Universidad de la República)

11:24 AM Doramad - The Story of Radioactive Toothpaste

Doramad Radioactive Toothpaste (Doramad Radioaktive Zahncreme) was a brand of toothpaste produced in Germany by Auergesellschaft of Berlin from the 1920s until the end of World War II. This talk will cover the history and marketing of the toothpaste and describe its chemistry and radiochemistry using samples issued to Wehrmacht units fighting on the Eastern Front in 1944/5.

Speaker: Dr Nick Evans (Nottingham Trent University)

11:42 AM Adaptations of Phaseolus vulgaris crop root exudate release to U(VI) in hydroponic environment

Adaptations of Phaseolus vulgaris crop root exudate release to U(VI) in hydroponic environment

Julia Marie Mätzkow*, Robin Steudtner, Frank Bok, Thorsten Stumpf, Susanne Sachs

Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
* j.maetzkow@hzdr.de

A crucial aspect of radioecology is assessing the risk of environmental contamination by radionuclides in order to protect life from ionizing radiation. Radionuclides released into the groundwater can be transported in soil and absorbed by crops. The ability of radionuclide to enter the food chain rises health concerns for humans. While non-essential for plants, depending on chemical speciation, radionuclides are taken up by them and induce morphological adaptations at multiple developmental stages, as well as changes in metabolic pathways and root exudate release patterns. Root exudates contribute to alterations in bacterial community composition within the rhizosphere and enhance nutrient absorption capacity. Given the capacity of root exudates to influence radionuclide speciation and mobility, they must also be considered when modelling radionuclide bioavailability in the environment. The purpose of this study is dual: first, to identify root exudates released into the rhizosphere in the presence of radionuclides, and second, to investigate radionuclide speciation.
This study analyzes the interaction between uranium (U) and the Phaseolus vulgaris crop in a hydroponic medium (phosphate-reduced, half-concentrated Hoagland) as a function of U concentration, pH, and exposure time. U bioassociation was determined by inductively coupled plasma-mass spectrometry. Modifications in U speciation in hydroponic culture were measured using time-resolved laser-induced fluorescence spectroscopy. Changes in root exudate release profiles were identified by high-performance liquid chromatography and non-target screening analysis in collaboration with the company AFIN-TS GmbH.
Both U bioassociation and phenotypic adaptations of the plant depend on exposure time, U concentration, and pH. Spectroscopic analysis revealed variations in the U speciation in hydroponic solution and were supported by thermodynamic calculations. The initial U speciation is characterized by various species, including sulfate, hydroxo, and carbonate complexes. Three main U(VI) species were detected (UO2(CO3)34-, (UO2)x(OH)y2x-y, uranyl(VI) malate) during plant U exposure. The uranyl(VI) malate complex, whose proportion rises with exposure time, is formed with malate as a well-documented root exudate. However, malate is not the sole root exudate released. Our investigation revealed elevated concentrations of organic acids and amino acids in U presence being able to modify bioavailability of U in the environment.
This study contributes to a better understanding of the interaction of U with plants, which is crucial for improving radioecological models assessing the behavior of radionuclides in the environment.

This research is part of the TRAVARIS project, funded by the German Federal Ministry of Research, Technology and Space under the contract number 15S9437C.

Speaker: Ms Julia Maetzkow (HZDR)

10:30 AM → 12:00 PM Radiopharmaceuticals: RPH1

Conveners: Martina Benešová-Schäfer, Constantin Mamat (HZDR)

10:30 AM Immunomodulatory Nanoradiopharmaceuticals—Preclinical and clinical investigations

Background: There is extensive clinical evidence that cancer patients receiving radiation therapy, during and after treatments, undergo severe suppression in cancer-killing immune responses. Although radiation therapy(TR) has proven to be highly effective in killing tumor cells, its collateral effects in causing extensive damage to healthy/normal cells, especially RT’s adverse and irreversible damages to cells within the immune system, has sparked extensive debate. There is also significant clinical evidence suggesting that patients during radiation therapy manifest measurable changes in cell signaling pathways resulting in alterations in the local immune microenvironment. Patients, post radiation therapy, display immunosuppressive phenotypes—presumably causing radio and chemo resistance of various different type of tumors. Circumventing these problems is not easy because molecular and cellular biology of neoplastic cells alone has failed to explain the non-uniform uptake of these radiation doses in tumors/normal cells. In order to employ radiation therapy as an effective tumor treatment protocol, it is imperative to develop radiation therapeutic systems that not only protect patients’ immune system but most desirably promote enhancement of immune system during and after radiation therapy regimens. Therefore, the discovery of new radiopharmaceuticals that effectively deliver radiation dose to tumors selectively while enhancing immune system of the body for synergetic immunotherapy of tumors.
Results and discussion: In our continued efforts to apply Green Nanotechnology for the development of therapeutic immunomodulatory radioactive gold nanoparticles, recently we have discovered that the high antioxidant capacity of various phytochemicals including Resveratrol(RES) or Epigallocatechin gallate (EGCG), can be used to convert radioactive Gold-198 precursor into the corresponding biocompatible and immunomodulatory radioactive gold nanoparticles. Receptor binding assays have confirmed that RES-198AuNP target Laminin receptors over expressed on Prostate and various Laminin receptor positive tumors. Immunomodulatory assays on RES-AuNPs have unequivocally confirmed that these nanoparticles enhance anti-tumor IL12 cytokines and suppress pro-tumor IL10 and IL6 cytokines. Cell signaling studies have confirmed that RES-AuNPs suppress NF-kB—primary signaling pathway directly involved in tumor growth and propagation. This lecture will provide: (a) scope and prospects of beta emitting immunomodulatory Au-198-based nanoradiopharmaceutical(s) in radiation therapy; (b) details on the intervention of nuclear activation analysis and various radioanalytical approaches for the production of tumor specific radioactive RES-gold-198 nanoradiopharmaceutical; and (c) full in vivo pre-clinical investigations on therapeutic properties of RES-198-AuNPs agent in treating prostate tumors and (d) the overall immunomodulatory implications of a library of Gold-198-based nanoradiopharmaceutiacls and (e) pilot clinical investigations in human patients showing the efficacy of immunomodulation of functionalized gold nanoparticles in treating human cancers.

Speaker: Kattesh Katti (University of Missouri)

10:56 AM Ultra-small gold nano-particles as carriers of Auger electron emitters for improved radionuclide targeted therapy

Auger electrons are known for their high linear energy transfer which can induce clustered DNA damage, leading to highly efficient cell death. Therefore, Auger electrons are ideal for attacking small metastatic tumors. In many cases, Auger electrons are typically emitted alongside other radiation such as gamma rays or positrons, which enable diagnostic imaging applications. Despite these advantages and years of research, only a limited number of radiopharmaceuticals using Auger emitters have been developed so far and only a few have reached clinical testing. This is largely due to the very short range of Auger electrons, which requires precise delivery of the emitters to critical cellular targets such as the nucleus.
In this study, we used ultra small gold nano-particles as carriers for the Auger emitter iodine-125 (125I) to create a new radiopharmaceutical.[1] After successful synthesis of nano-particles having less than 2 nm of diameter, the nano-carriers were radiolabeled with 125I. Radiolabeling yield was above 90 % and the stability remained above 95 % when tested in PBS for 72 hours. Cell studies in 2 D and 3D cell models showed low uptake as expected from literature but from the internalised particles around 30 % accumulated in the cell nucleus. This nucleus uptake proved to be sufficient to induce cell death even at low activities, i.e. 370 kBq, revealing the great potential of this approach. We have also shown that this approach can be extended to other Auger emitters such as 111In and other metallic nano-particles as longs as their size remains below 3 nm. Finally, we expect that the addition of tumour targeting vectors will improve the tumor-killing efficiency and we plan to investigate that in the future.
1. R. Wang, H. Liu, B, Antal, H, Th. Wolterbeek, A. G. Denkova, ACS Appl. Bio Mater. 2024, 7, 2, 1240–1249

Speaker: Antonia Denkova (TU Delft)

11:12 AM Development of Cage-Like Macropa Chelators for the Stable Complexation of Barium-131 and Radium-223

A detailed understanding of the coordination chemistry of heavy group 2 metal ions, particularly barium as a surrogate for radium, is essential for advancing radiopharmaceutical applications of radium. This is of particular importance as radium-223 is currently the only clinically approved therapeutic alpha-emitter (by EMA and FDA). However, its clinical applications remains limited. To date, radium-223 is exclusively administered as Xofigo® for the treatment of bone metastases. Macropa represents a promising chelator capable of coordinating Ba2+ and Ra2+. Nevertheless, the stability of the formed complexes is insufficient, leading to partial dissociation, release of Ra2+ and an accumulation in the bones.
To address these limitations, cage-like chelating systems based on the macropa aza-crown-ether skeleton containing a diester bridge were synthesized Three nicotinate-based diesters with varying chain lengths were prepared and reacted with diaza-18-crown-6 (Kryptofix® K22) under high-dilution conditions to ensure 1:1 macrocyclization, affording the desired cryptands in yields of 28–59%. The complex formation of these cryptands with Ba2+ was tested by 1H NMR showing a fast and quantitative complexation at room temperature. The pKa values were determined by NMR titration, and stability constants (logK) were obtained by isothermal titration calorimetry The solid-state structures of the complexes were elucidated by single-crystal X-ray diffraction analysis.
Based on these promising results, a radiolabeling protocol was established using the gamma emitter barium-131, which is suitable for SPECT imaging. All ligands were evaluated in a serial dilution (10-3 – 10-5 M) using 100 kBq of in-house produced 131Ba (TR-Flex cyclotron). As a result, a quantitative radiochemical conversion at a ligand concentration of 10-3 M was achieved for all new chelators as confirmed by radio-TLC analyses. A certain degree of transchelation is found in challenge experiments with EDTA in excess.

F. Reissig, et al. Nucl. Med. Biol. 2021, 98, 59
F. Reissig, et al. Pharmaceuticals 2020, 13, 272

Speaker: Constantin Mamat (HZDR)

11:28 AM Can the astatine atom in radiopharmaceuticals be involved in both halogen and hydrogen bond interactions?

Astatine (At, Z = 85) is a radioelement belonging to the halogen group. One of its isotopes, 211At is considered a highly promising candidate for targeted alpha therapy due to its favorable physical properties, including a half-life of 7.2 h and a 100% alpha-emission yield. A key prerequisite for its medical application is the development of stable labeling strategies that ensure the reliable attachment of 211At to carrier molecules. Achieving this goal requires a detailed understanding of astatine reactivity in chemical and biological environments.
As a halogen, astatine exhibits characteristic interactions such as halogen bonding, a directional noncovalent interaction that plays an important role in molecular recognition processes. Recent studies have provided evidence for the existence of halogen bonding involving astatine and prove that astatine is the strongest halogen bond donor atom. In 2024, the hypothesis emerged that At-mediated halogen-bond interactions with protein functional groups may be responsible for the in vivo dissociation of the At–C bond [4], while current 211At-labeling procedures are mainly based on the formation of this type of bonding. Due to astatine’s ability to act simultaneously as a Lewis base, the possible coexistence between halogen bonding and hydrogen bonding interactions may have additional consequences on the stability of radiopharmaceutical candidates.
In this work, we investigate the binding behavior of astatine monoiodide with methimazole, a widely used drug for the treatment of hyperthyroidism, as a model ligand able to act as both a Lewis base and a hydrogen bond donor. Experimentally, two complexes were identified using a liquid–liquid competition method: one formed in aqueous solution and another formed in CCl4 solvent. The corresponding formation constants were determined. DFT calculations confirm that the complex formed in aqueous solution is primarily stabilized by halogen bonding, whereas the complex formed in CCl4 is strengthened by one additional hydrogen bond. This work highlights the synergy between different noncovalent interactions in astatine-containing molecules, which could have important implications for the design of more stable astatine-based radiopharmaceuticals.

Speaker: Lu Liu

11:44 AM Synthesis and characterization of macropa-based complexes for the stable coordination of radiometals

Radiometals play an essential role in the context of both radiopharmacy and radioecology, two scientific fields that seem unrelated but that are, nevertheless, connected through the fundamentals of radiochemistry. In either case, the selective and stable coordination of radiometal ions represent key objectives in the development of ligands. While radiopharmacy covers the use of radiolabeled compounds for targeted therapy and imaging for diagnostics, radioecology focuses on processes such as in vivo metal sequestration for decorporation, or immobilization for environmental remediation or nuclear waste disposal. As there is no ligand that can form stable complexes with every radiometal, an optimization of the ligands’ complexation behavior is a vital objective in these areas.
In this work, the relationship between ligand structure and complex stability was investigated using a series of macropa-based ligands. Five derivatives containing different electron–withdrawing groups (EWGs) and electron–donating groups (EDGs) on the aromatic rings – hydroxy, dimethylamino, chloro, fluoro, and nitro – were synthesized with the purpose of modulating the HSAB properties of the ligand and evaluating inductive and/or mesomeric effects on metal coordination. La(III) with La as a β+ emitter used in PET imaging and as counterpart for the α emitter Ac-225, Pb(II) with Pb-203 as γ emitter for SPECT and Pb-212 as β- emitter for cancer treatment, Ba(II) with Ba-131 as γ emitter for SPECT and the α emitter Ra-223 were selected for this study. Ligand protonation (pKa) constants, essential to later calculate the stability constants, were obtained by 1H NMR spectroscopic pH-titration, with values ranging from 2.0 to 3.5 for the carboxylate functionalities, 6.5 to 8.0 for the amino functionalities and 11.3 for the hydroxy groups. Further structural characterization of the ligands and complexes was performed via NMR. Thermodynamic parameters for complexation with La(III), Pb(II) and Ba(II) were determined by isothermal titration calorimetry, allowing the calculation of reaction enthalpies, stability constants (log β) and pH-dependent affinities. Complementary thermodynamic data for Eu(III) complexes were obtained using time-resolved laser-induced fluorescence spectroscopy. Radiolabeling studies were conducted at ligand concentration ranging from 10^(-5) to 10^(-7) M for La-133, Pb-203, and Ac-225 and 10^(-3) to 10^(-7) M for Ba-131 and Ra-223. Complex formation and radiochemical stability were evaluated using normal-phase and reverse-phase thin-layer chromatography, revealing the following trend: Pb-203 > La-133 > Ba-131 ≈ Ra-223. Remarkably, ligands bearing EWGs (Cl, F, NO2) exhibited enhanced Ba-131 complexation in comparison to those containing EDGs (NMe2, OH), whereas with La-133 an opposite effect was observed, where ligands containing EDGs exhibit increased La-133 complexation. These results show the different complexation behavior with the different metals and highlight the potential of tailoring these ligands in the development of radiopharmaceuticals and complexing ligands for environmental immobilization of radiometals or their sequestration for decorporation.

Speaker: Rodrigo Castro Biondo (Helmholtz-Zentrum Dresden-Rossendorf)

12:00 PM → 1:30 PM Lunch

1:30 PM → 3:00 PM Radiation Chemistry: RCH 1

Conveners: Eros Mossini (Politecnico di Milano), Jan Bárta (Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering)

1:30 PM Extreme Light Infrastructure – Research Opportunities in Radiation Science

The Extreme Light Infrastructure ERIC (ELI ERIC) is a recently established international research infrastructure providing access to advanced sources of ultrashort pulse laser light and secondary radiation. The infrastructure currently operates three user facilities located in Czechia (ELI Beamlines), Hungary (ELI ALPS), and Romania (ELI NP), offering state of the art experimental stations in an open user access regime organized through joint international calls. A subset of the available instruments is directly dedicated to, or particularly well suited for, research in radiation sciences, including radiation chemistry, radiation physics, and radiobiology.
This contribution focuses on the ELI Beamlines Facility (Dolní Břežany, Czechia) and highlights radiation sources and recent developments relevant to future research in radiation chemistry. At ELI Beamlines, radiation sources of particular relevance include femtosecond extreme UV pulses (10–120 eV) available at the HHG MAC station, sub picosecond X ray pulses delivered by the Plasma X ray Source operating at repetition rates up to 1 kHz, and femtosecond X ray pulses from the GAMMATRON high energy betatron source. Complementary charged particle sources include femtosecond electron pulses from the ALFA laser driven electron accelerator and nanosecond ion pulses with energies up to 20 MeV/Z (protons and carbon ions) produced by the ELIMAIA ion accelerator.
The combination of ultrashort pulse durations, high peak dose rates, and diverse radiation modalities enables new experimental approaches for studying radiation induced chemical processes. The presented overview aims to inform the radiation chemistry community about the available capabilities and emerging opportunities for user driven experiments at ELI Beamlines and about the details of the user beamtime application process.

Speaker: Dr Martin Precek (ELI ERIC)

2:00 PM Determination of Hydroxyl Radicals in Aqueous Systems Exposed to Low-Energy X-Rays

Hydroxyl radicals ($\mathrm{^\cdot}$OH) are among the key reactive species formed in the course of water radiolysis and they play an important role in subsequent radiation-induced chemical processes in aqueous environment. Quantitative data on $\mathrm{^\cdot}$OH formation under low-energy X-ray irradiation, however, remain limited. In this work, hydroxyl radical formation in aqueous systems irradiated with X-rays in the energy range of 25–300 kV was investigated using chemical dosimetry.

Terephthalic acid (TA) and coumarin-3-carboxylic acid (C3CA) were used as chemical sensors to quantify $\mathrm{^\cdot}$OH production through the formation of fluorescent products. Radiation chemical yields were derived from fluorescence measurements of 2-hydroxyterephthalic acid and 7-hydroxycoumarin-3-carboxylic acid. Chromatographic analysis was used to confirm product identity and to support the interpretation of the fluorescence data.

The measurements provide experimental information on hydroxyl radical formation in water exposed to low-energy X-rays and contribute additional data to study of water radiolysis in this energy region. The results represent the capabilities and limitations of fluorescence-based chemical dosimetry for investigating $\mathrm{^\cdot}$OH formation under low energy photon irradiation.

This work has been funded by a grant from the Programme Johannes Amos Comenius under the Ministry of Education, Youth and Sports of the Czech Republic SENDISO, project No. CZ.02.01.01/00/22_008/0004596 and by the Ministry of the Interior of the Czech Republic (OPSEC programme), project No. VK02020047

Speaker: Kristýna Havlinová

2:20 PM Scintillating (Ce,La)F3:Tb3+ nanoparticles for XPDT: evaluation of dark and radiation-induced cytotoxicity.

Rare-earth-based fluoride nanocomposite materials represent a promising platform for applications in radiation-based cancer therapies, particularly in the context of X-ray induced photodynamic therapy (XPDT) [1,2]. Due to their scintillation properties, these materials are capable of converting the ionizing radiation into UV/visible photons, enabling in situ activation of photosensitizers within tumor tissue. A key requirement for biomedical application of the nanoparticles is their low dark toxicity, together with the ability to provide enhanced radiation-induced biological effects upon excitation by ionizing radiation.
Our work focuses on the in vitro evaluation of the cytotoxicity of Tb-doped $\text{LaF}_3$ and $\text{(Ce,La)F}_3$ nanoparticles using the PANC-1 pancreatic adenocarcinoma cell line. The $\text{LaF}_3\text{:Tb}^{3+}$ (5%) and $\text{Ce}_{0.15}\text{La}_{0.80}\text{F}_3\text{:Tb}^{3+}$ (5%) systems were selected based on the previous comparative studies of Ce- and Tb- co-doped lanthanum fluorides, which identified these compositions as promising candidates with prospective physicochemical and optical properties relevant to XPDT [3, 4]. Dark toxicity experiments were assessed over a range of nanoparticle concentrations (up to 1,5 mg/mL) to define a safe concentration window for subsequent experiments. To evaluate nanoparticle-related effects under irradiation, experiments were performed at different radiation doses using irradiation in the SCIOX beam X-ray cabinet.
This study represents an initial step towards the development of $\text{(Ce,La)F}_3$-based scintillating nanocomposites for XPDT treatment. The obtained results will serve as a basis for future experiments combining nanoparticles with photosensitizers and ionizing radiation to achieve the desirable therapeutic outcome resulting from the dual effect of ionizing radiation in the course of radiotherapy: (1) the direct damage and (2) the damage caused by photosensitizer-mediated production of reactive oxygen species.

[1] A. Dorokhina, et al. “Solvothermal synthesis of $\text{LaF}_3\text{:Ce}$ nanoparticles for use in medicine: luminescence, morphology and surface properties,” Ceramics 6, 1 (2023).
[2] K. Popovich, et al. “Preliminary study on singlet oxygen production using $\text{CeF}_3\text{:Tb}^{3+}\text{@SiO}_2$-PpIX,” Radiat. Meas. 90 (2016).
[3] X. Lytvynenko, et al. “Optimization of the Fabrication of Luminescent Nanocrystalline $\text{Ce}_x\text{La}_{1-x}\text{F}_3\text{:Tb}^{3+}$ for XPDT Applications,” IEEE Trans. Nucl. Sci. 72 (7) (2025).
[4] X. Lytvynenko, et al. “Composition-dependent properties of $\text{Ce}_x\text{La}_{0.95-x}\text{Tb}_{0.05}\text{F}_3$ nanopowders tailored for X-ray photodynamic therapy and cathodoluminescence imaging,” Radiat. Meas. 189 (2025).

This work has been funded by a grant from the Programme Johannes Amos Comenius under the Ministry of Education, Youth and Sports of the Czech Republic SENDISO, project No. CZ.02.01.01/00/22_008/0004596; by the Ministry of the Interior of the Czech Republic (OPSEC programme), project No. VK02020047; European Union’s Horizon Europe’s Marie Skłodowska-Curie Actions - Co-funding of Regional, National and International Programmes (MERIT - Grant Agreement No. 101081195). This work was performed within the frame of Crystal Clear Collaboration.

Speaker: Xenie Lytvynenko (Czech Technical University in Prague)

2:40 PM Deepest studies of the effects and implications of TODGA radiolytic degradation compounds on actinides partitioning processes

Closing the fuel cycle to promote a safe and sustainable nuclear energy requires capabilities to reprocess and multi-recycle U but also major (Pu) and minor actinides (MA: Am, Cm, Np) into new fuels for advanced reactors. Nowadays, the hydrometallurgical processes are the most mature technology able to address actinides recycling within this context, although they are not exempt of important challenges. For example, one of the keys for the development of new and advanced processes requires designing highly selective extraction systems but also to deal with their degradation and regeneration due to the effect of the strongly radiative field and nitric acid concentration where nuclear fuel must be dissolved [1]. In that sense, the objective is not perfect resistance to the aggressive medium, but sufficient for a safe and efficient industrial implementation of the processes. Within this framework, diglycolamides (DGA) are considered as one of the most promising extractants for lanthanides and actinides, and currently engaged in many advanced separation strategies. During the past decades, it has been acquired a lot of knowledge and experience about the stability of DGA based-solvent, and particularly about TODGA (N,N,N´,N´-tetraoctyldiglycolamide), being very revealing the studies exploring the individual properties of degradation compounds and their correlation with the behavior of the system after irradiation [2-5].
In an effort to increase the ability to predict the evolution and performance of these new extracting systems against radiation, the trend in our stability studies is moving toward deepest evaluation of the composition in the long term and a more integrated exploration of robustness, designing more realistic experiments that mimic the solvent degradation. This work summarizes our latest studies conducted for a better understanding of the effects and implications of TODGA radiolytic degradation compounds on actinides partitioning processes.

[1] P. Baron, S. Cornet, E. Collins, G. DeAngelis, G. Del Cul, Y. Fedorov, J. Glatz, V. Ignatiev, T. Inoue, and A. Khaperskaya, "A review of separation processes proposed for advanced fuel cycles based on technology readiness level assessments," Progress in Nuclear Energy, vol. 117, p. 103091, 2019.
[2] H. Galán, A. Núñez, A. G. Espartero, R. Sedano, A. Durana, and J. de Mendoza, "Radiolytic stability of TODGA: characterization of degraded samples under different experimental conditions," Procedia Chemistry, vol. 7, pp. 195-201, 2012.
[3] I. Sánchez-García, H. Galán, J. M. Perlado, and J. Cobos, "Stability studies of GANEX system under different irradiation conditions," EPJ Nuclear Sciences & Technologies, vol. 5, p. 19, 2019.
[4] Y. Sugo, Y. Sasaki, and S. Tachimori, "Studies on hydrolysis and radiolysis of N, N, N′, N′-tetraoctyl-3-oxapentane-1, 5-diamide," Radiochimica Acta, vol. 90, pp. 161-165, 2002.
[5] C. A. Zarzana, G. S. Groenewold, B. J. Mincher, S. P. Mezyk, A. Wilden, H. Schmidt, G. Modolo, J. F. Wishart, and A. R. Cook, "A comparison of the γ-radiolysis of TODGA and T (EH) DGA using UHPLC-ESI-MS analysis," Solvent Extraction and Ion Exchange, vol. 33, pp. 431-447, 2015.

Speaker: Dr Hitos Galán (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT))

1:30 PM → 3:00 PM Separation & Speciation: SEP 5

Conveners: Alex Tarancon Sanz (Universitat de Barcelona), Mojmír Němec (Czech Technical University in Prague, FNSPE, Department of Nuclear Chemistry)

1:30 PM Inorganic Resin Materials for the Separation of Ra-223 and Ac-225

Introduction
Due to the very promising properties of α-emitting radionuclides for cancer therapy, there is a high interest in α-emitters such as actinium-225. However, the poor availability of Ac-225 limits research, necessitating the development of new production routes. When using radium or thorium as target material, these new routes result in a highly active mixture of radionuclides from which the Ac-225 has to be separated. Currently, organic ion-exchange resins are applied for this separation, but they suffer from radiolytic degradation. As inorganic materials are generally much more radiation resistant, this research investigated the separation of radium and actinium using inorganic resins.

Methods
Four inorganic resin materials were examined, of which zirconium phosphate (ZrP) and titanium phosphate (TiP) were synthesized via the direct precipitation method, and zirconium oxide (ZrO₂) and cerium oxide (CeO₂) were purchased. Ra-223 and Ac-225 were used as target and product radionuclide tracers, with the chemically similar barium and lanthanum added to mimic more realistic concentrations. The sorption and reaction kinetics were determined in batch by contacting the resin material with stocks of different pH at different interaction times. Subsequent column experiments were performed using ZrP as resin material. The columns were run at a flow rate of 0.4 ml/min, loaded at neutral pH, after which the residual Ra-223 was washed off using a pH 3 HNO₃ solution and the Ac-225 was eluted with 1 M HNO₃.

Results
During the batch sorption experiments, it was found that neither Ac-225 nor Ra-223 were adsorbed at pH 1 for all four sorbents. The Ac-225 adsorption increased with pH, i.e. more than 97% of Ac-225 was adsorbed by ZrP, TiP and CeO₂ at a neutral pH, while for ZrO₂ only about half (55.7 ± 0.5%) of the Ac-225 was adsorbed. At this pH, the Ra-223 co-adsorption by CeO₂ and ZrO₂ was low, about 6 ± 1%, but relatively high (51 ± 5%) for the ZrP and TiP resin materials. Nevertheless, the kinetics experiments demonstrated that the Ac-225 adsorption by ZrP was much faster than that of Ra-223, making it still a viable option as resin material. Therefore, considering its exchange characteristics, synthesis and particle size, ZrP was selected as the most promising resin material.
Column experiments using ZrP as resin material demonstrated high loading efficiencies of Ac-225 (99.99 ± 0.02% ). Co-adsorption of Ra-223 was relatively high (40.9 ± 0.7%), but could mostly be washed off (33 ± 2%) using a pH 3 solution, with only very limited Ac-225 breakthrough (0.2± 0.4%). Near complete elution (99.2 ± 0.7%) of the Ac-225 was achieved using 1 M HNO₃, accompanied by 7% of the Ra-223, demonstrating the separation capabilities of ZrP.

Concluding, different resin materials were tested of which ZrP seemed the most promising and column experiments demonstrated its potential for the separation of Ra-223 and Ac-225. Therefore, ZrP is a promising candidate to utilize in the production of Ac-225, overcoming radiolytic degradation issues of current organic alternatives.

Speaker: Esther Spruit (Tu Delft)

1:48 PM Ti-based core-shell shaping for Ac-225/Bi-213 separation

Cancer remains one of the leading causes of death worldwide, requiring innovative methods for its treatment such as targeted alpha therapy with Bi-213-based radiopharmaceuticals. Alpha radiation is especially promising as it enables maximum destruction of malignant cells while minimizing cytotoxicity on the surrounding healthy tissue. However, current challenges in separating the radioactive Bi-213 from the mother Ac-225 isotope prevent more widespread use in a clinical environment despite the promising results. Therefore, the development of an innovative new sorbent material with a long operational lifetime (~10 days), shaped to enable the required fast (de)-sorption kinetics (≥80% Bi-213 yield in 2 mL eluate), is needed. Moreover, the harsh separation conditions—exposure to highly acidic media (< pH 3) and high radiation doses (~10 MGy absorbance over 2 weeks)—limit the number of materials qualified for this application. Although inorganic support materials show potential, they need to be shaped to an appropriate macroscopic architecture which allows sufficiently fast (de)-sorption kinetics. The aim of this work is to develop a micron-sized core-shell type stationary phase consisting of a Ti-support with tuned surface porosity that promote the desired fast (de)-sorption kinetics, while adjusting chemical composition and structural features to provide optimal separation performance (selectivity and yield) in combination with radiation and acid stability.

Speaker: Thomas Staes (SCK CEN)

2:06 PM The development of a separation method for ¹¹¹Ag from neutron‑irradiated Pd targets using dimethylglyoxime

Ag-111 is a radionuclide with prospective applications in the field of theranostics, i.e. the simultaneous imaging and treatment using a single radiopharmaceutical. It is a beta-decaying nuclide, with the emitted beta particles having suitable energies ($E_{β,mean}=$360 keV) for traversing only short distances within the tissues and interacting almost exclusively with cancer cells. Beta decay is accompanied by the emission of two relatively low energy gamma rays (245 and 342 keV) that can be utilized in the application of the Single Photon Emission Computed Tomography (SPECT) technique for diagnosis. Nevertheless, several drawbacks related to the production of the radionuclide have hindered research and development of Ag-111-labelled drugs. Neutron irradiation of palladium targets is the most common method to produce Ag-111, via the activation of naturally occurring Pd-110 nuclei and the subsequent decay of activation product Pd-111 to Ag-111. However, purity and total activity of the final product can be negatively affected due to the complexity of Ag/Pd separation and the limited natural abundance of the Pd-110 isotope.

The scope of the present work was to develop and optimize a method for the quick and efficient separation of Ag-111 from the Pd target matrix for future applications in medical research. Pd targets weighing up to 20 mg were irradiated under neutron flux (maximum 3.9E+12 $cm^{-2}$$s^{-1}$) for up to 12 h at the TRIGA MARK II research reactor of Jožef Stefan Institute, Ljubljana, Slovenia. Total Ag-111 activities and radionuclidic impurities were determined at the end of irradiation by gamma spectrometry. In our previous studies, efficient Ag/Pd separation was achieved with Ni Resin, but only batch mode was effective for larger target masses. In order to further simplify this process, dimethylglyoxime (DMG), the active component of the resin which binds Pd(II) ions, was used instead of a chromatography resin, to quickly and selectively precipitate Pd from the dissolved target. Ag-111 was then separated and isolated, and separation efficiencies and method performance was compared with the method involving Ni Resin. Finally, a recovery procedure using ascorbic acid was applied to almost quantitatively retrieve the original Pd target, for additional irradiation cycles.

Speaker: Filippos Karantoumanis (Jožef Stefan Institute)

2:24 PM Scrubbing of radium from a loaded organic phase in milliflow reactors: detection challenges and performance optimization for medical radioisotope purification by solvent extraction

Objective and method

Actinium-225 (²²⁵Ac) is a promising radionuclide for targeted radionuclide therapy (TRNT), but current production methods cannot meet market demand. Innovative selective transmutation pathways have been researched to increase the market supply, particularly those exploiting the ²²⁶Ra photonuclear reaction. A novel solvent extraction (SX) methodology based on intensified milliflow reactors has been developed to provide a continuous and reliable means of separating actinium from the radium target. Particularly, the scrubbing step in the process was studied in a single-stage milliflow reactor using $5\ M$ HNO₃ solution as the scrubbing agent solution to remove the co-extracted radium. The loaded organic phase was prepared by testing two loading strategies for the short-lived ²²⁴Ra radionuclide, namely Loading-by-Extraction (LBE) with a high phase ratio extraction and Loading-by-Dissolution (LBD) achieved by contacting the solvent with dried radium nitrate. The aim is to maximize the loading of radium in the organic solution, in order to precisely measure the activity left in the scrubbed solvent. The scrubbing tests were carried in parallel for the two radium-loaded organic phases using a single-stage milliflow reactor setup, comprising of two syringe pumps, tubing with internal diameter of $1\ mm$ as the reactor and a 3D-printed in-line phase separator using Millipore$^{\circledR}$ membranes. The samples were collected at steady state after three residence times and analyzed by HPGe gammaspectrometry (i.e. High-Purity Germanium gamma spectrometry) to detect the activity (Bq) of radium in the solvent after one scrubbing stage, evaluated by means of the scrubbing efficiency ($\% E_{scrubbing}$ eq 1), where $\left[ A \right] _{loaded\ solvent}$ is the activity in the solvent after scrubbing and $\left[ A \right] _{extract}$ is the activity in the solvent before the scrubbing step.
Equation 1: $ \%E_{scrubbing}=\left( 1-\frac{\left[ A \right] _{loaded\ solvent}}{\left[ A \right]_{extract}} \right) 100 $
Results

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The solvent was loaded with radium in both cases, the LBE strategy yielded a feed with $490 \pm 26$ Bq/mL, on the other hand LBS yield amounted to only $320 \pm 20$ Bq/mL. The speciation of the radium present in the loaded solvent could be affected by the loading technique, but there was no significant difference in scrubbing efficiency. Nonetheless, the LBE method was preferred since the mass transfer of radium occurred as liquid-liquid inter-phase complexation, opposite to a less representative and efficient direct organic dissolution. The best performance was achieved by setting the flowrate of each phase at $0.5\ mL/min$ and using a $3000\ mm$ reactor, resulting in a residence time of $170\ s$, for the LBE solvent yielding $ 96.6 \% \pm 7.4 \% $ scrubbing efficiency. A second experiment was performed with the longest residence time reactor repeated in a cross-flow three-stage scrubbing protocol, using LBE solvent and fresh scrubbing agent solution. The scrubbing efficiencies were $95.9 \% \pm 7.5 \%$, $79.2 \% \pm 27.5 \%$, and $4.3 \% \pm 8 \%$, for the first, second and third stages, respectively. The overall scrubbing efficiency of $99.20 \% \pm 7.6 \%$. Such evidence indicates that the three-stage scrubbing achieved close to quantitative radium removal from the solvent. Future work should focus on obtaining higher activities of ²²⁴Ra to reduce the uncertainty of the measurement.

Speaker: Mr Samuele Servici (SCK CEN & KU Leuven)

2:42 PM Extraction of radon from spring water into vegetable oils: Production of highly active preparations for medicinal purposes

The carcinogenicity of residential radon (222Rn) has long been scientifically discredited.
Positive correlation between radon and lung cancer is based on LNT (Linear-no-threshold-theory) only. No correlation here, when assumption-free statistics applied. On the other hand, radon is successfully used in balneology due to its strong hormetic effects.
In radon balneotherapy, in some cases, the natural source activity for a stronger treatment may be inadequate low. Therefore, a several field experiments was made to produce a highly active preparations, by extracting radon from water into sunflower, rapeseed, and olive oil. For comparison, extraction into dodecane, which is the most lipophilic, was also tested.
The natural radon springs Břetislav (activity around 12.5 kBq/L 222Rn) and Pod Skalou (activity 5–8 kBq/L 222Rn), discovered in 2017 and 2017 in western Bohemia, were used as sources. The waters of both sources are cold and low in mineral content.
Extraction was carried out in a “2 L” glass separating funnel. About 2 liters of fresh water were always used, the starting amount was 120 ml of oil. A series of extractions was performed in the following steps. Previous experiments had shown that 3 to 4 consecutive extractions were sufficient to saturate the oil.
When using an air bubble and shaking, extraction ratios of around 10 were achieved. Significantly better results were achieved by mixing with a milk frother in a full funnel, where air access was limited.
Olive, sunflower, and rapeseed oils had similar extraction ratios, ranging from 16.2 to 17.3 and dodecane to 20, although upto 45 reported in the broad literature. The best prepared sunflower oil preparation had an activity of 213 kBq/L 222Rn. Discussions are currently underway with doctors about the possibilities of using this activated oil in spa treatments.

Speaker: Viktor Goliáš (Charles University in Prague, Faculty of Science, Department of Geochemistry, Mineralogy and Mineral ressources)

3:00 PM → 3:30 PM Coffee Break

3:30 PM → 5:00 PM Radionuclides Production & Application: PAR 2

Conveners: Dominic Maertens (PanTera NV), Jiří Mizera (Nuclear Physics Institute, Academy of Sciences of the Czech Republic)

3:30 PM Molybdenum Disulfide Nanotubes for the Next‑Generation ⁹⁹Mo/⁹⁹ᵐTc Generator

Technetium-99m (^99mTc) remains the most widely used gamma emitting radionuclide for diagnostic nuclear medicine. At present, its production relies predominantly on the fission of uranium-235 (²³⁵U) to generate the parent isotope molybdenum-99 (⁹⁹Mo), a process that produces substantial quantities of long-lived nuclear waste and raises concerns regarding long-term sustainability, making the development of cleaner and more sustainable production pathways of ^99mTc of critical importance. Direct production routes based on the neutron irradiation of enriched ⁹⁸Mo or ¹⁰⁰Mo offer an attractive alternative; however, these approaches yield ⁹⁹Mo with low specific activity because ⁹⁹Mo cannot be separated from the chemically identical bulk molybdenum target material. Moreover, the conventional alumina-based adsorbents are unable to accommodate the large molybdenum mass associated with these routes. Overcoming these limitations requires the development of a fundamentally new generator concept capable of operating at significantly higher molybdenum loadings.
Molybdenum-based nanomaterials provide a promising solution, as they can be engineered to function simultaneously as irradiation targets and generator materials. Such material enables the retention of ⁹⁹Mo within the solid matrix while allowing selective extraction of ^99mTc. In this work, we investigated molybdenum-based nanomaterials, specifically molybdenum disulfide (MoS₂), which exhibit controlled self-assembly into hierarchical nanotubes (NT). The as-synthesized NT were subsequently heat-treated to remove residual octyl amine, resulting in calcinated nanotubes (C-NT). Both NT and C-NT exhibited low ⁹⁹Mo breakthrough in Milli-Q (0.06% and 0.01% respectively) and in methylethylketone (MEK) (0.1% and 0.0005%, respectively). The comparatively higher ⁹⁹Mo breakthrough for NT in Milli-Q and MEK is attributed to the partial and complete solubility of octyl amine in these solvents, respectively. The extraction efficiency of ^99mTc in Milli-Q was approximately 15% for NT. In MEK, the ^99mTc extraction efficiency for NT increased significantly to ~30%, accompanied by a substantial (~25%) increase in ⁹⁹Mo breakthrough, again linked to the presence of octyl amine. In contrast, C-NT exhibited consistently low extraction of ^99mTc extraction efficiency (<2%) in Milli-Q and MEK. These results highlight the critical role of residual organic ligands in governing both ^99mTc extraction efficiency and ⁹⁹Mo breakthrough. These findings demonstrate the potential of molybdenum-based nanomaterials as next-generation ⁹⁹Mo/^99mTc generator systems, paving the way towards more sustainable and waste-minimized ^99mTc production.

Speaker: Gauri (Delft University of Technology)

3:48 PM Photonuclear Reactions: The Future of Large Scale Theranostic Radionuclide Production for Medical Applications

Photonuclear reactions have been known since nearly 100 years, but only recently, discussions about using this type of reaction for the production of radionuclides for medical applications (i.e. diagnosis and therapy) have surfaced. In a photonuclear reaction a high-energy gamma-ray is interacting with a target nucleus, whereby a particle (or several particles) such as protons or neutrons are ejected. Such (gamma,n) or (gamma,p)-reactions give access to several, medically interesting radionuclides.
With the commercial availability of high-energy and high-power electron accelerators, intense Bremsstrahlung can be generated, which is able to induce photonuclear reactions. Although the reaction cross sections are lower compared to particle-induced reactions, the penetrating nature of heigh-energy gamma-rays allows the use of much thicker targets, largely overcompensating the lower reaction cross section.
There remain a number of challenges to be solved before a large scale production of radionuclides can be envisaged. First, the intense electron beam of typically about 40 MeV energy and about 125 kW of beam power has to be converted to Bremsstrahlung. This is done by means of a converter target that must be able to withstand the enormous beam power. Second, the chemical separation of radionuclides in no-carrier added form from several tens of grams of target material remains a chemical challenge.
In the presentation, the testing of a prototype of a so-called Tesla converter that was designed to absorb 125 kW of beam power [1,2] is discussed as well as calculations of the yield of photonuclear reactions with high-power accelerators. Furthermore, first examples of experiments conducted at the 22 MeV microtron for the production of Sc-47, Cu-67 and Pm-149 in Bern are presented.
[1] A. Türler, M. Vagheian, H. Lüthi, High Power Converter Target Assembly, Related Facility and Method to Produce Bremsstrahlung for Photonuclear Reactions, EP4191613A1
[2] M. Lüthi, A. Türler, High Power Point-Source Converter Target Assembly, Related Facility and Method to Produce Bremsstrahlung for Photonuclear Reactions Using an Electron Linear Accelerator or an Electron Accelerator with Similar Time Structure of the Beam, EP4425509A1

Speaker: Prof. Andreas Türler (University of Bern)

4:06 PM Production and radiochemical separation of no‑carrier‑added ¹⁴⁹Pm for medical application

Pm-149 is a promising β⁻-emitting radiolanthanide with moderate beta decay energy (Eₘₐₓ = 1.07 MeV) and a half-life of 53.1 hours. Besides these therapeutic characteristics, ¹⁴⁹Pm also emits a low-abundance imageable gamma ray at 286 keV with an intensity of around 3%. However, its broader clinical translation is currently limited by challenges in reliable production and efficient radiochemical purification from rare-earth target materials.

This work evaluates feasible production routes for no-carrier-added ¹⁴⁹Pm based on irradiations of natural Nd metal via the reaction ¹⁵⁰Nd(γ,n)¹⁴⁹Nd → ¹⁴⁹Pm with a microtron, of enriched ¹⁵⁰Nd₂O₃ through the reaction ¹⁵⁰Nd(p,2n)¹⁴⁹Pm with a cyclotron, and of enriched ¹⁴⁸Nd₂O₃ via the reaction ¹⁴⁸Nd(n,γ)¹⁴⁹Nd → ¹⁴⁹Pm with a nuclear reactor, considering practical constraints such as beam energy, target stability, and impurity formation. Experimental irradiations were complemented by yield estimations and radionuclidic impurity assessments using HPGe γ-spectrometry.

A robust post-irradiation separation strategy was developed to achieve efficient lanthanide separation under mild conditions. Dissolution of irradiated targets in nitric acid was followed by cation-exchange chromatography employing α-hydroxyisobutyric acid (α-HIBA) as an eluent to separate ¹⁴⁹Pm from bulk neodymium. Process parameters, including pH, flow rate, and fraction collection, were systematically optimized. Further purification using extraction chromatography (LN₃ resin) was investigated to enhance chemical purity.

The separation performance was evaluated by γ-spectrometry, ICP-MS, and radio-HPLC, enabling assessment of radiochemical yield, decontamination factors, and trace-metal impurities. The obtained ¹⁴⁹Pm exhibited high radionuclidic and radiochemical purity. To demonstrate its applicability for radiopharmaceutical use, ¹⁴⁹Pm was successfully radiolabeled with PSMA I&T, achieving high labeling efficiency and radiochemical purity as confirmed by radio-HPLC analysis.

This study demonstrates the production and separation of nca ¹⁴⁹Pm up to therapeutically relevant activity levels and paves the way for its future routine preparation for targeted radionuclide therapy.

Speaker: Xiuyun Chai

4:24 PM Proton-Induced Reactions at Intermediate Energies: The Missing Experimental Basis and the Infrastructure Bottleneck

Intermediate-energy cyclotrons providing 25–60 MeV proton beams represent essential infrastructure for generating the experimental nuclear-reaction cross sections required for credible cyclotron-based applications. This energy interval uniquely encompasses the regime in which reaction yields, radionuclidic purity, and impurity formation are governed by rapidly varying excitation functions arising from the opening and competition of multiple emission channels and the increasing relevance of isomeric population. Measurements restricted to ≤30 MeV are frequently insufficient to characterise these processes under realistic production conditions, while higher-energy accelerator platforms are not generally available for systematic, high-resolution activation campaigns. Consequently, the experimental cross-section database above 30 MeV remains markedly incomplete and methodologically heterogeneous, with deficiencies in energy coverage, inter-laboratory consistency, and traceable uncertainty quantification; these limitations propagate into persistent, energy-dependent discrepancies between measured data and model-based evaluations, thereby constraining both production optimisation and the validation and improvement of reaction modelling in the intermediate-energy domain. The urgency is intensified by the progressive loss of intermediate-energy cyclotron capability, as numerous facilities have been decommissioned, shut down, or repurposed, reducing access to the very beam energies required for modern cross-section benchmarking. To address these gaps, systematic activation campaign spanning threshold to 60 MeV on an intermediate-energy cyclotron will be performed, applying harmonised protocols and fully traceable uncertainty budgets to deliver internally consistent excitation functions suitable for benchmark-driven model refinement. Sustained operation of intermediate-energy cyclotrons, together with coordinated, harmonised activation measurements across threshold to 60 MeV supported by rigorous uncertainty budgets, is therefore a prerequisite for re-establishing a coherent and reliable nuclear-data basis for cyclotron applications.

Speaker: Tomasz Mróz (Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences)

4:42 PM Production and radiochemical separation of ²⁵⁵Fm for nuclear science applications

The study of chemical and physical properties of actinides is of essential interest in the field of nuclear science. Our group at Mainz University specializes in the production and characterization of tailor-made actinide samples for both national and international collaborations. Einsteinium (element 99) and fermium (element 100) have been in our focus most recently. A sample of Es-254, received in 2019 from the high-flux reactor of ORNL, via Florida State University, USA, was irradiated at the high-flux reactor at ILL, France, producing Es-255 (T1/2 = 39 days). Es-255 decays via beta-decay into Fm-255 (T1/2 = 20 hours), which provides a basis to develop a generator-like system. The separated Fm-255 as well as the Es isotopes were used for laser spectroscopic studies carried out by our colleagues of the institute of physics at JGU and at GSI/FAIR Darmstadt.
In this presentation, we will focus on the chemical challenges of sample preparation, purification and analytics in the frame of this project.

Speaker: Andrea Tzeitel Loria Basto (Johannes Gutenberg Universität Mainz)

3:30 PM → 5:00 PM Nuclear Analytical Methods: NAM 5

Conveners: Eros Mossini (Politecnico di Milano), Nora Vajda (RadAnal Ltd.)

3:30 PM Selection criteria for ionic liquids for actinide electrodeposition in alpha-spectrometric source preparation

Electrodeposition is a key step in the preparation of thin, homogeneous sources for high-resolution alpha-spectrometric analysis of actinides. Conventional aqueous electrolytes often suffer from limited electrochemical windows, hydrolysis of actinide species, and insufficient control over deposit morphology. Ionic liquids (ILs) and deep eutectic solvents (DES) have emerged as promising alternative media due to their wide electrochemical stability, low vapor pressure, and enhanced complexation capabilities.
This work presents a conceptual and literature-based selection of selected ILs and DES as prospective electrodeposition media for actinides, with a specific focus on applications in radiochemical analysis. Selection criteria included electrochemical stability window, viscosity and ionic conductivity, hydrophilicity, metal-ion complexation behavior, chemical stability under radiochemical conditions, and practical aspects such as availability and cost. Based on these criteria, imidazolium-based ILs (e.g., EMIM-DCA and EMIM-BF4) and choline-chloride-based DES (choline chloride–urea and choline chloride–ethylene glycol) were identified as promising candidates.

Speaker: Tereza Tomanová (NBC Defence Instituce)

3:48 PM A Study of Simple Alpha Source Preparation using a Micro-coprecipitation Method

This study presents a rapid and simple alpha source preparation method for environmental and radioactive waste samples. Among the numerous methods for alpha source preparation such as electrolytic deposition, direction evaporation, vacuum sublimation and electrospraying, the most widely used for preparation of actinides for alpha spectrometry is electro-deposition. However, this procedure is time consuming, requires expensive elaborate equipment as well as precise pH control. Thus, the present study provides simple and reliable alpha source preparation for actinides, optimizing various parameters such as weight and variety of lanthanides carrier, time of alpha source preparation and various membrane filters for micro-precipitation. Also, radiochemical recoveries and energy resolutions of actinides with optimizing micro-precipitation method have been compared with those with electrodeposition method.

Speaker: MYUNG HO LEE (KRIST)

4:06 PM Optimized Characterization Strategy for Activation Products in NPP Metallic Waste

Over decades of nuclear power plant (NPP) operation, many metallic structural components undergo various degrees of neutron activation. As these large-scale components reach their operational limits, they are replaced and transferred to interim storage. In this stage, an accurate estimation of radionuclide inventories is essential for establishing effective strategies in handling, transportation, and final disposal of such radioactive waste.
This study presents an optimized strategy to quantify activation products within activated metal waste. The methodology is refined according to activation levels, material types, and specific target radionuclides to facilitate systematic characterization. A key focus of this work is the radiochemical analysis of activated metal samples retrieved from domestic NPPs. Through this analytical framework, we investigate the relationship between 60Co, a dominant and easily measurable gamma-emitter, and various difficult-to-measure (DTM) nuclides such as 55Fe, 59Ni, and 63Ni.
By integrating non-destructive measurement techniques with in-depth destructive radiochemical analysis, this study allows for a streamlined approach to inventory estimation that minimizes worker radiation exposure and analytical costs, providing a rigorous technical basis for standardized protocols in the management of legacy metal waste. Furthermore, the techniques developed in this study are highly transferable to future decommissioning projects, providing a scalable framework for managing the vast quantities of metallic waste.

Speaker: Dr Tae-Hong Park (Korea Atomic Energy Research Institute, University of Science and Technology)

4:24 PM Validation and verification of direct tritium determination method from waters (drinking, surface, ground waters, waste waters and operational from nuclear facilities)

Tritium (T) is a radioactive isotope of hydrogen that is formed naturally in the environment through interaction of cosmic rays in the upper layers of atmosphere by interaction of neutrons with nitrogen or oxygen gasses. Most of the resulted atmospheric tritium is oxidized to form of tritiated water (HTO) and introduced to water cycles. Other forms of tritium can be found in the environment such as tritium gasses (HT, and CH3T) or organically bound tritium (OBT). Anthropogenic tritium is a result of human activities such as nuclear weapons tests, reprocessing of spent nuclear fuel and nuclear reactors. Due to the ban of nuclear weapons testing tritium is gradually decreasing back to background level. Nowadays concentrations of tritium are just locally enhanced by spent nuclear fuel reprocessing centers and operation or decommissioning of nuclear reactors. Because of the decrease of tritium in the environment there is a huge demand for sensitive and accurate method of tritium determination. This study aims for validation and verification of direct tritium (in form of HTO) determination method by liquid scintillation counting by ISO EN 9698:2019. During the study, certified reference materials and internal standards were used, and all measuring instruments were verified or calibrated by national authorities. During the study all key validation and verification parameters, including precision, trueness, reproducibility, bias, and sensitivity, met or exceeded the acceptance criteria. The strong inter-operator agreement and low measurement uncertainties confirm that the method is reliable, accurate, and robust for determining low levels of tritium in the drinking waters, surface waters, ground waters, waste waters and operational waters from nuclear facilities. While there are many articles about the tritium our goal was not to introduce fundamentally new physical principle for tritium determination by LSC, but to provide a fully validated and verified analytical procedure compliant with international quality and metrological standards with traceability. The novelty of this work lies in the complete validation framework applied to tritium measurements by LCS and certification approach adopted for routine and regulatory applications. The study was conducted under stable environmental conditions during standard operation of nuclear power plant and the laboratory environment conditions were also monitored. Strong emphases were placed on environmental and laboratory conditions for the purpose of validating and verifying the method in Testing laboratory of radiochemical analysis accredited according to EN ISO/IEC 17 025.

Speaker: Dominik Juracka (Department of Nuclear Chemistry, Faculty of Natural Sciences Comenius University Bratislava)

4:42 PM From linear/impregnated to crosslinked/porous/covalent grafted plastic scintillation resins: a robust plastic scintillator platform for high capacity separation and on column detection of radionuclides

Plastic scintillation microspheres (PSm) combined to selective extractants (PSresins) enable single support separation and direct counting of α/β emitters, but their broader advance is hindered by two constraints: (i) limited extractant loading on low area linear polystyrene, which caps capacity, and (ii) chemical stability (solvent attack and leaching) in non-aqueous or reprocessing like media. We address both limitations through a three step strategy: (1) crosslinked microspheres (CPSm) to gain robustness while preserving scintillation; (2) porosity engineering (p CPSm and macroporous PSm) to boost accessible surface and extractant amount; and (3) covalent functionalization of crosslinked supports (f CPSresin) to suppress leaching and operate in aggressive media.
First, dispersion polymerized CPSm (30–100 µm) including styrene and divinylbenzene displayed detection efficiencies comparable to linear PSm for medium/high energy β and α emitters, together with markedly enhanced thermal/solvent resistance; only low energy β (³H) shows a moderate decrease at high DVB proportions due to chain rigidity and wetting effects. These materials withstand organic solvents without morphology loss, enabling post synthesis processing (e.g., pore generation, surface chemistry).
Second, we introduced porosity at two scales. p CPSm were obtained by adding porogens (toluene, n heptane) during CPSm polymerization; changing the monomer:porogen ratio modified bulk density and spectral shifts, evidencing pore formation, and the expected optical quenching increase. P CPSm with 2:1 toluene:monomer proportion retained acceptable scintillation while allowing higher extractant immobilization and improved column handling (lower stickiness, better packing). In parallel, macroporous PSm prepared by evaporation–extraction with linear polystyrene and non volatile porogens (e.g. heptane) increased surface area without degrading radiometric performance. When loaded with Aliquat 336 for pertechnetate, the macroporous supports admitted ×2–×3 extractant and delivered clear capacity gains with sustained efficiency and no early leaching (stable beyond 150 mL).
Third, to operate in hydro organic and TBP/dodecane media, where impregnated PSresins fail by leaching/dissolution, we created a covalently functionalized resin (f CPSresin). Crosslinked scintillators were chloromethylated via the Blanc reaction; this surface route minimized quenching versus the formation of a copolymer with chlorostyrene. Subsequent reaction with trioctylamine produced quaternary ammonium sites linked to the polymer. Despite a reduction in scintillation output (∼40 % ⁹⁹Tc efficiency), the resin showed high aqueous performance (96–97 % ⁹⁹Tc retention at 10⁻³ M HCl; Re capacity 23.4 mg g⁻¹) and, critically, acceptable extraction in hydro organic media (≈40 % in MeOH, up to 98 % in acetone) while keeping stable spectra. In 30 % TBP/dodecane, f CPSresin preserved structure and counting response (⁹⁹Tc retention ≈32 %; efficiency ≈41 %), demonstrating applicability in reprocessing type matrices where classical PSresins dissolve.
Across cartridge tests, porous/crosslinked platforms immobilize substantially more extractant than non porous analogues, translating into higher capacities at quantitative ⁹⁹Tc retention once pore filling thresholds are met; leaching after large rinsing volumes is negligible, and spectral shifts are minor. The covalent route complements this by extending the applicability range to aggressive media at the cost of a moderate quenching compatible with routine quantification.

Speaker: Alex Tarancon Sanz (Universitat de Barcelona)

5:15 PM → 6:30 PM Environmental Radioactivity: Poster session

5:15 PM Phosphorylation of Amino Acids with a PO2 Synthon and Their Interaction with f-Elements

To reveal the biological uptake of f-elements after an unintended release to the environment, a deeper understanding of their interaction with biomolecules is of great importance. Due to its hard Lewis basic character, the phosphoryl group is known to display a strong affinity towards certain metals. In the case of some biomimetic proteins, phosphoryl groups are present in the form of phosphoserine residues, and studies have shown that they display increased affinity for f-elements. For this reason, studying the interactions between phosphorylated amino acids and f-elements was envisioned to improve our fundamental understanding of the biological uptake of f-elements. Thus, phosphorylated amino acids were chosen as model compounds.

The phosphorylation of amino acids was achieved with the phosphorylation reagent (py)₂PO₂[OTf] (py = pyridine), a versatile PO₂⁺ synthon capable of reacting with various nucleophiles. The model compounds were obtained by reacting this phosphorylation reagent with various protected amino acids. The coordination properties of these model compounds towards f-elements were investigated using La(III), Sm(III), and Lu(III) as early, middle, and late lanthanide representatives. The binding behaviour of these model compounds will be presented.

Speaker: Jeremy Long

5:18 PM Synthesis of Phosphorylated Peptides Using (py)2PO2[OTf] and Their Interaction with f-Elements

Uranium and rare earth mining, the extensive use of mineral fertilizers, nuclear weapons programs, and reprocessing plants have released significant amounts of lanthanides and actinides worldwide. The environmental contamination with f-elements can pose severe health risks, especially if they enter the human food chain. Hence, a deeper understanding of the interaction of f-elements with biochemical motifs is crucial for risk assessment and hazard management.

Studies on metalloproteins like transferrin, calmodulin, and siderocalin have revealed strong interactions with f-elements. Particularly high affinities are found for phosphoproteins like casein or phosvitin, which contain high levels of phosphoserine residues. For a detailed understanding of the binding modes and preferred coordination sites in amino acid/peptide-f-element systems, systematic investigations remain essential.

With this aim, the novel phosphorylation agent (py)₂PO₂[OTf] (py = pyridine, OTf = triflate) was used to functionalize dipeptides to obtain a library of bio-inspired model compounds. Their interactions with f-elements were subsequently studied. Systems of the unmodified dipeptides as well as the model compounds were investigated in combination with various Ln(III) and uranyl(VI) ions in solution using heteronuclear NMR and fluorescence spectroscopy. The results, including complex stoichiometries and identified coordination sites, are presented.

Speaker: Tom Pfandt (TU Dresden)

5:21 PM Accelerator Mass Spectrometric Analysis of ¹²⁹I/¹²⁷I ratios in INL sagebrush modelling FCF pyroprocessing’s impact on environmental iodine levels in the Idaho desert

Understanding the environmental distribution of radioiodine isotopes produced during pyrochemical reprocessing is critical for evaluating the ecological footprint of next-generation nuclear fuel-cycle facilities. We analyze ¹²⁹I/¹²⁷I ratios in sagebrush (Artemisia tridentata) and in collected air masses across the Idaho National Laboratory (INL) desert complex using Accelerator Mass Spectrometry (AMS) to assess a detection framework for potential emissions from INL’s Fuel Conditioning Facility (FCF). Comparisons between vegetation- and atmosphere-derived isotopic ratios establish a basis for distinguishing localized source terms from background signals.

Environmental ¹²⁹I/¹²⁷I ratios associated with historic operations at INL’s Idaho Chemical Processing Plant (ICPP) are evaluated in conjunction with National Oceanic and Atmospheric Administration (NOAA) historical wind data. A spatial transport framework is developed to describe wind-driven redistribution of soil-bound iodine as a function of downwind and crosswind distance from the primary source term. Application of a general linear regression model yields exponential decay constants corresponding to a downwind e-folding distance of 14 km and a crosswind half-width e-folding distance of 13 km. Analysis of sampled air masses indicates that particulate, soil-bound iodine contributes minimally to atmospheric iodine isotope ratios, suggesting that observed signals primarily reflect gaseous or direct atmospheric source terms.

Speaker: Mr Jacob Brookhart (Idaho National Laboratory)

5:24 PM Retrospective determination of ¹³¹I thyroid equivalent doses via ¹²⁹I AMS analysis

I-131 is a radionuclide that, in the event of a nuclear accident, contributes the most to the radiation dose to members of the public. Since such exposure occurs within the first few days following a radioactive release, large-scale determination of the effective dose is virtually impossible.
Current monitoring of I-131 activity concentrations in the Czech Republic relies on HPGe gamma spectrometry measurements of samples from only ten high-volume air sampling stations. Most of the area remains therefore uncovered.
Aim of the presented work is to build a system capable of determining I-131 activity concentration as well as thyroid equivalent dose retrospectively via I-129 in soil samples analyses. The condition of the procedure viability is to be capable to distinguish between I-129 of pre-accident and accident origin and the knowledge of I-131 to I-129 deposition density ratio during the accident (Michel et al. 2005). While I-131 to I-129 deposition density ratio in particular geographical area can be accessed from mathematical simulation retrospectively, reliable determination of I-129 of pre-accident origin has to be conducted in advance due to huge differences in I-129 activities caused by Chornobyl accident. Specific areas of interest within the Czech Republic were selected for the monitoring of current I-129 activity concentrations in soil. These included regions poorly covered by the existing monitoring system, areas heavily affected by Chornobyl fallout, densely populated zones, and border regions in close proximity to nuclear power plants (NPPs).
For needs of determination of I-129 activity concentration in soil samples a radiochemical procedure was utilized and optimized for best optimal yields of iodine separation from solid environmental media, involving especially various types of soils and sediments. For these materials, 5–10% TMAH solutions typically provide near-quantitative yields for total iodine separation. This approach was combined with subsequent liquid-liquid extraction to chloroform in the acidic pH range, followed up with re-extraction and co-precipitation as silver iodide. The oxidation states during the procedure were adjusted accordingly with K2S2O8, Na2SO3 and NaNO2 agents. Samples were analysed with MILEA AMS beamline at ÚJF Řež for 129I content, total iodine concentration was determined in parallel by ICP-MS. The analysis of 129I was performed utilizing I-/I2+ analytical setup, with the primary ions being extracted from AgI(+Nb) target matrices in Ti cathodes, used for suppression of molecular isobars, and the high energy beamline efficiency corrected to the ETH Zurich isotope reference material C.2-39.
The retrospective calculation of the thyroid equivalent dose is based on the methodology established by Pietrzak-Flis et al. (2003).
This conference contribution presents a comprehensive methodology proposal for the retrospective estimation of I-131 thyroid equivalent doses, based on accelerator mass spectrometry (AMS) analyses of I-129.
This research is co-funded with state support from the Czech Technology Agency under the SARA project (SQ01010334), Environment for Life 2 Programme. The infrastructure of the AMS laboratory built under the RAMSES project was used in the research realization.

Speaker: Michal Fejgl (National Radiation Protection Institute)

5:27 PM Onboard Rapid Determination of Radiocesium in Seawater: Development and Operational Application in Open-Ocean Monitoring

Quantification of marine radionuclides remains analytically demanding due to their ultratrace concentrations and the need for large sample volumes and extensive pretreatment procedures. Conventional protocols typically involve multi-day chemical separation, prolonged counting times, and sample transport to land-based laboratories, resulting in total turnaround times of several weeks to months. Such constraints significantly limit the capability for rapid response in the event of accidental releases from nuclear facilities, particularly under dynamic oceanographic conditions characterized by rapid advection, dispersion, and dilution.

Here, we report the development and field implementation of an onboard rapid analytical system for the determination of radiocesium (134Cs and 137Cs) in seawater. The method integrates accelerated pre-concentration chemistry with optimized gamma spectrometric measurement, enabling full onboard processing from large-volume seawater to quantification within hours. The pre-treatment and cesium concentration procedure, which previously required several days, has been reduced to approximately four hours without compromising analytical performance.

Using this system, we successfully quantified background 137Cs levels of approximately 1 mBq/kg directly onboard research vessels. The method allows analysis of two samples within 12 hours, achieving a minimum detectable activity (MDA) of <0.2 mBq/kg. Comparative analyses with conventional land-based laboratory methods showed agreement within 10% for more than 92% of samples.

To further validate analytical robustness, a full-process intercomparison was conducted using a certified reference seawater, including large-volume standard seawater pretreatment, chemical analysis, and instrumental measurement. Both 134Cs and 137Cs results exhibited biases within 10% of certified reference values, confirming the accuracy and reliability of the developed methodology.

Since 2023, this onboard rapid-detection system has been operationally deployed in South Korea’s official open-ocean radioactivity monitoring program, led by KIOST. The system has been deployed during repeated North Pacific expeditions aboard R/V ISABU, demonstrating its capability for real-time assessment of basin-scale radiocesium distribution and emergency-response readiness.

Speakers: Ms Jaeeun Lee (Korea Institute of Ocean Science and Technology (KIOST)), Dr Intae Kim (Korea Institute of Ocean Science and Technology (KIOST))

5:30 PM Bacillus pasteurii Ureolytic Products Coupled with U(VI) Immobilization: The Evolutionary process and action mechanism of Carbonate and Metabolic Protein

This study investigates the biogeochemical cycling of carbon and phosphorus during ureolysis-driven uranium immobilization in mining-impacted waters, where Bacillus pasteurii utilizes urea as a carbon/nitrogen source to generate carbonate ligands and metabolic proteins. We demonstrate that bacterially derived carbonate complexes competitively inhibit U(VI) phosphate crystallization (H₂(UO₂)₂(PO₄)₂·8H₂O) by binding to UO₂²⁺ ions ((UO₂)CO₃·2H₂O), while prolonged metabolic activity releases inorganic phosphate and phosphorylated proteins, enabling the re-precipitation of uranyl phosphate minerals. Metabolic proteins act as critical drivers of mineral maturation, solidifying pre-nucleation clusters into hybrid organic-inorganic crystalline phases via scaffolding effects. Density functional theory (DFT) simulations quantitatively resolve a urea-dependent coordination shift: UO₂²⁺ transitions from an initial 5-coordinate configuration (bound to HPO₄²⁻, membrane -COOH, and PO₄³⁻ groups) to a 6-coordinate state after 8 h ureolysis, dominated by tridentate carbonate ligation yet retaining trace PO₄³⁻/-COOH coordination, confirming ligand substitution-driven expansion of the uranyl coordination sphere. These results elucidate how microbial C/P cycling and secretory proteins synergistically regulate uranium biomineralization dynamics, offering novel strategies for targeted uranium sequestration in carbonate-rich wastewaters.

Speaker: Xiaojing Lu

5:33 PM Basin-scale redistribution of Cs-137 and Pu-239,240 in the western Indian Ocean: A 6-decade perspective

The Indian Ocean has received limited attention in global assessments of anthropogenic radionuclides, despite its substantial role in inter-ocean exchange. Here we present distributions of Cs-137 and Pu-239,240, representative artificial radionuclides, in the western equatorial Indian Ocean between 2017 and 2023. Surface activities of Cs-137 and Pu-239,240 in the study region have decreased exponentially, corresponding to reductions of 19–48% for Cs-137 and 30–40% for Pu-239,240 over the past two decades. In the western Indian Ocean, the long-term decrease of Cs-137 is driven mainly by the surface current system, whereas Pu-239,240 is controlled predominantly by particle reactivity and vertical redistribution. The redistribution of Cs-137 indicates gradual lateral homogenization, with weak retention near the equator, suggesting that basin-scale mixing rather than meridional migration dominates its spatial distribution. The temporal evolution of Cs-137 and Pu-239,240 activities yields effective environmental half-lives of 24.8 ± 6.7 years and 10.1 ± 4.5 years, respectively, in the western Indian Ocean. These findings provide a comprehensive multi-decadal framework characterizing the western Indian Ocean not merely as a passive sink, but as a transit region where distinct oceanographic processes regulate the long-term redistribution of anthropogenic tracers.

Speaker: Jaeeun Lee (Korea Institute of Ocean Science and Technology (KIOST), University of Science and Technology (UST))

5:36 PM Hidden bioremediation potential: metal-tolerant rhizobacteria capable of barium and strontium removal from uranium-impacted ecosystems

Barium (Ba) and strontium (Sr) are non-essential, potentially toxic elements frequently associated with radioactive waste from abandoned uranium mines. Their chemical similarity to alkaline earth metals, particularly calcium (Ca), enables biological substitution that may disrupt cellular processes in living organisms. Despite their environmental relevance, microbial tolerance mechanisms toward Ba and Sr remain insufficiently characterized. This study investigates the diversity and metal tolerance of bacteria inhabiting a wetland ecosystem impacted by historical uranium mining.
Inductively coupled plasma mass spectrometry (ICP-MS) detected Ba and Sr, together with U and other trace elements, in rhizosphere of Scirpus sylvaticus collected from the rhizosphere of a wetland downstream of the former uranium mine at Zadní Chodov, Czech Republic. High-throughput 16S rRNA gene analysis revealed a microbial community dominated by Proteobacteria and enriched with metal(loid)-tolerant genera, including Pseudomonas, Flavobacterium, Novosphingobium, Pelosinus, and Thiothrix. These taxa are commonly associated with metal-contaminated environments and are known to employ diverse resistance strategies, such as metal efflux, enzymatic detoxification, biosorption to cell surfaces, extracellular polymeric substance production, oxidative stress mitigation, and metal(loid) reduction.
Cultivation-based methods yielded 70 bacterial isolates exhibiting substantial metal tolerance. Minimum inhibitory concentration assays demonstrated resistance to U (up to 8 mM) and multiple co-occurring metals, including Pb (up to 16 mM), Cu and Co (up to 4 mM), Zn (up to 8 mM), and Se (up to 32 mM). Selected strains, such as Curtobacterium flaccumfaciens, Paenibacillus amylolyticus, Allorhizobium sp., Commamonas jiangduensis, Chryseobacterium carnipullorum, and Herbaspirillum aquaticum displayed pronounced tolerance to Ba and Sr in growth experiments and showed measurable biosorption capacity, highlighting their adaptive potential in multi-metal environments. These findings advance current understanding of microbial adaptation to Ba- and Sr-enriched habitats and identify promising candidates for environmentally sustainable remediation strategies. Harnessing such microbial processes may improve the evaluation of contaminant mobility and bioavailability while supporting the development of green technologies for the restoration of metal(loid)-impacted ecosystems.
Acknowledgment. This work was supported by SURRI project GA No 101079345, provided by HORIZON Twinning in 2024 and the Student Grant Competition SGS-2024-3490.

Speaker: Vira Velianyk (Technical University of Liberec)

5:39 PM Spatially Resolved and Radiochemical Characterization of Strontium in Ivory by Combined LIBS and AMS Analysis

Hard mineralized tissues such as ivory represent valuable archives of environmental and biological information and are frequently the only available material in archaeological, environmental, and forensic investigations. In addition to age determination, which is essential for assessing the legality of ivory artefacts, information on geographic origin and dietary history is crucial for conservation research and anti-poaching efforts. These parameters can be reconstructed through a combination of elemental and isotopic analyses.
This study presents a complementary analytical approach combining spatially resolved Laser-Induced Breakdown Spectroscopy (LIBS) with Accelerator Mass Spectrometry (AMS) for the investigation of strontium distribution and isotopic composition in ivory samples.
LIBS was employed to determine spatially resolved Ca/Sr ratios across ivory cross-sections. In the LIBS technique, a short, high-energy laser pulse is focused onto the sample surface, leading to rapid local heating, micro-ablation, and vaporization of nanogram to microgram quantities of material. The ablated material forms a transient high-temperature plasma plume. During plasma cooling, excited atoms and ions emit characteristic optical emission lines that are spectrally resolved for qualitative and quantitative elemental analysis. This approach enables micrometer-scale mapping of elemental distributions with minimal sample preparation and quasi-nondestructive character. The obtained LIBS maps revealed a periodic structure in strontium distribution, reflecting biological growth increments. Variations in Ca/Sr ratios between samples indicate differences in environmental strontium availability and dietary intake. The Sr/Ca ratio was evaluated from the ratio of Gaussian-fitted integrated intensities of the Sr I 460.7 nm and Ca I 452.7 nm emission lines. For radiochemical characterization, isotopic ratios $^{88}\mathrm{Sr}/^{90}\mathrm{Sr}$ were determined by AMS. The presence of $^{90}\mathrm{Sr}$, a long-lived anthropogenic fission product, provides information related to nuclear fallout and environmental contamination history, while the stable isotope $^{88}\mathrm{Sr}$ serves as a reference for total strontium normalization. A correlation between the AMS-derived isotopic ratios and the LIBS-determined Ca/Sr values enabled estimation of total strontium concentrations and cross-validation of elemental quantification. Additionally, $^{14}\mathrm{C}$ analysis was performed to determine the age of the ivory samples, providing chronological context necessary for forensic and legal assessment.
The integration of spatially resolved elemental mapping (LIBS) with highly sensitive isotopic analysis (AMS) represents a powerful radiochemical–analytical strategy for the investigation of ivory. This combined methodology allows simultaneous evaluation of growth-related elemental patterns, environmental isotopic signatures, and chronological information. The approach expands the application of radiochemical techniques in cultural heritage studies and contributes to improved provenance determination and monitoring of illegal ivory trade.

Speaker: Alena Zavadilová (Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering)

5:42 PM From Surfaces to Transport: In Situ Insights into f-Element Retention under Close to Nature Conditions

A reliable understanding of radionuclide (RN) migration in potential host rock formations is essential for the long-term safety assessment of radioactive waste disposal. During recent decades, major progress has been achieved in this field. Nevertheless, relevant knowledge gaps remain, especially for complex and transient systems at close to nature boundary conditions. The transfer of parameters from simplified batch experiments to dynamic transport systems is still associated with considerable uncertainty.
Within the ongoing research project SPIEG3L, an integrated experimental and analytical approach is developed to investigate RN retention processes in situ. Column experiments are performed under saturated, artificial natural conditions. The focus lies on the trivalent f-element Eu, which serve as chemical analogues for actinides. An innovative combination of state-of-the-art spectroscopic methods is applied directly to the transport experiments. This approach allows the identification and differentiation of surface processes such as sorption, incorporation, surface precipitation, and changes in speciation.
The column experiments are to be coupled to logging systems. These systems enable continuous monitoring of pH, electrical conductivity, and tracer concentrations. Embedded markers that can be retraced ensure that each following analytical technique is applied to the identical sample locations. This multilevel analytical concept allows the identification of surface complexes and high-affinity sorption sites.
The experimental results will be used to develop surface complexation models. These models are subsequently implemented and verified in one-dimensional reactive transport simulations. The derived parameters support the linkage between laboratory-scale experiments and large-scale safety assessment calculations. Overall, SPIEG3L contributes to an improved process-based understanding of RN transport under artificial natural conditions.

Speaker: Andrea Kozlowski

5:45 PM Distribution of ¹³⁷Cs in the Tropical Pacific: Impact of Climate Variability on the North Equatorial Current (NEC)

In the marine environment, Cs-137 in the water column has been used as an effective tracer for tracking origin of water mass and circulation. To evaluate the spatiotemporal (biannual) variations of Cs-137, we investigated the vertical distributions of 137Cs and hydrography along the latitudinal (13.5° N) transect of the North Equatorial Current (NEC) region (of the Tropical Pacific) in 2024-2025, on board the Research Vessel ISABU of the Korea Institute of Ocean Science and Technology (KIOST), Cs-137 activity from 2024 to 2025 ranged from 0.43±0.08-2.95±0.49 mBq/kg in the upper water column (<500 m) [mean 1.51±0.25 mBq/kg (n=126)]. The vertical distribution of Cs-137 was higher in the high-salinity subsurface (200-300 m) than in the surface water. The observed subsurface Cs-137 maximum likely reflects isopycnal transport of recently introduced mid-latitude (30-40°N) North Pacific surface waters with elevated Cs-137 levels from the Subtropical Gyre into the North Pacific Tropical Water (NPTW). Such distribution through intrusion and mixing processes may have contributed to the development of the subsurface maximum (200-300 m depths), which is consistent with previously reported Pacific-wide Cs-137 distribution patterns. While the peak activity of Cs-137 was observed at depths of 100-200 m in 2024, it was at 200-300 m in April and November 2025. In 2024, the North Pacific experienced a transition from El Niño to La Niña. Therefore, it is thought that the overall deepening of NPTW together with the thermocline is due to the accumulation of Tropical Surface Water (TSW) driven by the strengthening of the northeast trade winds. These findings suggest that Cs-137 in the water column can be a useful tracer of the behavior, circulation, and redistribution of water mass fluctuations due to climate variability and other anthropogenic radioactive contaminants in the North Pacific.

Speaker: Eun-Ran Baek (Korea Institute of Ocean Science and Technology (KIOST), University of Science and Technology (UST))

5:48 PM Kinetics of cobalt and europium adsorption on nanoplastic particles in natural waters

Public concern about plastic pollution has led to rapid advances in detecting microplastics in environmental and biological samples. Currently, most research focuses on microplastics, while nanoplastics (NPs), which are more mobile in the environment and more harmful, have received less attention. Heavy metals and radionuclides adsorbed on colloidal-sized nanoparticles (< 1000 nm) can be transported over long distances in the environment and pose a threat to wildlife and humans.
This research aimed to study the adsorption kinetics of Co²⁺ and Eu³⁺ on real-life NPs, prepared from single-use plastic bottles and packaging materials by mechanical fragmentation and nanoprecipitation. Natural seawater and river water samples with a similar pH of 7.2 and varying salinity from 0 to 7 psu were used in the adsorption kinetics and desorption experiments. Adsorption was studied in batch experiments using solutions traced with 152Eu and 60Co, as well as polystyrene (PS) and polyethylene terephthalate (PET) samples. Particle sizes of PS and PET NPs ranged from 11 to 130 nm. The activity concentrations of 152Eu and 60Co were measured by gamma spectrometry with HPGe detectors. Nanoplastic samples were characterised using X-ray photoelectron spectroscopy (XPS), attenuated total reflectance infrared spectroscopy (ATR-FTIR), and Raman spectroscopy before and after adsorption. The kinetic adsorption data were more consistent with a pseudo-second-order non-linear kinetic model. Significant variations in desorption patterns were found depending on nanoparticle size and experimental conditions.

Speaker: Dr Galina Lujaniene (Center for Physical Sciences and Technology, Vilnius, Lithuania)

5:51 PM Determination of isotope-specific soil–plant transfer factors for ²²⁶Ra and ²²⁸Ra in German crops

Despite ²²⁶Ra and ²²⁸Ra deriving from different decay chains, the activity ratio in foods can reveal important aspects of radium transfer processes from soil to plants and further on along the food chain. Although ²²⁸Ra and ²²⁶Ra are frequently found in soils and waters at activity concentrations approximately 1:1, ²²⁸Ra has not yet been systematically measured on a comparable scale to ²²⁶Ra. There are no global compilations for typical ²²⁶Ra/²²⁸Ra activity ratios in soils available. Only several studies were focused on both Ra soil-to-plant transfer factors using the same plant species (Linsalata et al., 1989; Cooper et al., 1995; Sheppard et al., 2008 etc). In those papers there is evidence for a transfer factor of ²²⁸Ra being larger than that for ²²⁶Ra. The recent data analysis from these studies carried out as the initial phase of the present reseach showed that the difference is by a factor of about 1,7. However, most of publications have a lack of important supplementary data (pH value, temperature, soil moisture, chemical and granulometric composition of the soil, precipitations, etc.) that could potentially explain the observed differences in the transfer between ²²⁸Ra and ²²⁶Ra to plants.
One possible explanation for the differences in the transfer factors for ²²⁸Ra and ²²⁶Ra is that the parent isotopes ²³²Th and ²³⁰Th are present in different phases or with different sorption strengths. This can influence how much of the daughter radium is released and becomes biologically available. Currently, the transfer of both long-lived ²²⁶Ra and ²²⁸Ra isotopes are treated with the same transfer factor. Despite the relatively small contribution of radium isotopes to the total radiation dose, an underestimation of the dose caused by ²²⁸Ra is possible as it has one of the highest dose conversion factors for ingestion among the natural radionuclides.
This research initiated by the German Federal Office for Radiation Protection aims to examine whether the general assumption of isotope-nonspecific soil-plant transfer factors for ²²⁶Ra and ²²⁸Ra is justified. Testing this hypothesis, the research will either confirm the existing conservative assumption or incorporate the newly determined, nuclide-specific transfer factors for ²²⁶Ra and ²²⁸Ra into relevant areas. The study selected 5 locations in different regions of Germany with different concentrations of radium in the soil. Vegetables and fruits and the corresponding soil samples were collected mainly from farm fields. They include fruit and vegetable species typical for studied regions: potatoes, carrots, onion, spinach, cauliflower, apple, pear, strawberry, plum, and pasture grass. Corresponding to the plant locations, the soil in which the plants grow was sampled, so that the soil-plant transfer factors can be calculated. In addition, it is planned to conduct experiments with plants grown in containers in a phytochamber and outdoors.
The harvested crops are washed, dried at T = 105 C, ashed at T = 450 C for 24 h and measured with HP-Ge gamma spectrometer in the Petri dish geometry. The soil samples are dried at T = 105 C and measured also with HP-Ge gamma spectrometer in Marinelli beaker geometry. Further measurements of the subsequent crop and soil batches this year will provide an opportunity to identify more detailed trends in the accumulation of ²²⁸Ra and ²²⁶Ra isotopes by the studied crop species and thus to reveal the potential differences in their uptake by estimating the transfer factors, as well as access their contribution to the internal radiation dose.

Speaker: Dr Sergiy Dubchak (Leibniz University Hannover)

5:54 PM Uranium concentrations in groundwater on a uraniferous region: Case of Santa Quitéria, Ceará State, Brazil

The main uranium deposit in Brazil is located in the Itataia Mine, between the municipalities of Santa Quitéria and Itatira, State of Ceará, with estimated resources of around 142,000 tons.
Uranium in Itataia does not occur in isolation but is associated with phosphate. The project plans to separate the phosphate and uranium. Phosphate will be used for fertilizers and animal nutrition, while uranium will be used for nuclear fuel for power reactors installed in Brazil. When operational, it is expected to produce approximately 2,300 tons of uranium concentrate and more than 1 million tons of phosphate fertilizers annually.
The project faces resistance from local communities due to high water consumption in a semi-arid region and risks of radioactive contamination. Tests carried out in deep wells in the town of Trapiá, in Santa Quitéria, identified uranium concentrations seven times higher than the limit allowed for human consumption in Brazil (0.03 mg/L). The uranium concentrations in groundwater observed in the region are related to the local geology, which is rich in uranium and phosphates, and not to the operation of a mine, which has not yet begun operations.
About 40 groundwater samples were collected in the municipalities of Santa Quitéria and Itatira, from residences and public buildings. The uranium concentration ranged from <0.001 to 0.186 mg/L, with a median of 0.014 mg/L. The observed maximum value was consistent with previously reported data. Of the total samples collected, 24 were also analyzed for major cations and anions, as well as trace elements. The main issue found was the hardness, with 90% of the samples exceeding the limit established in Brazilian legislation of 300 mg/L.

Speaker: Prof. José Marcus Godoy (Pontifícia Universidade Católica do Rio de Janeiro)

5:57 PM Study of radiocesium removal from aqueous environment using high-charge swelling clays

Migration of radioactive substances into aquatic environments remains a major concern for nuclear accident preparation and environmental protection. In particular, the role of caesium isotopes can be emphasised, as they are characterized by high migration efficiency. One of the areas of research in this field is the search for effective sorbents to be used as barriers or for environmental decontamination.
Due to the negative surface charge and high specific surface area clay minerals are widely studied as potential Cs sorbents. Because of significant variations in properties, including layer charge and interlayer swelling behaviour, clay minerals have fundamentally different caesium absorption mechanisms and selectiveness, which justifies studies of different mineral compositions for cesium removal. This study provides new insights, into adsorbtion properties of Fe-beidellite from Bełachatów, Poland, and its potential for the removal of radiocesium from waters of different ionic compositions (including seawater).
The material used in the current study was a natural beidellite-bearing clay (bentonite) exploited selectively at the Belchatów mine (Poland) from the overburden of brown coal. The material was collected in 2018 from a stockpile at the Chabielice unit belonging to the Bełchatów Coal Mine. Quantitative XRD analysis of the sample, performed using the Rietveld method, revealed a composition of 62% wt smectite, 26% wt. quartz, 6% wt. kaolinite, 4% wt. dioctahedral mica,~1% wt., amorphous material and <1% anatase.
Adsorbtion experiments were performed using 134Cs as a radiotracer in deionised water, tap water, and synthetic seawater that simulates the salinity of the Baltic Sea. Two experimental configurations were applied. One in which a portion of clay was placed inside dialysis tubing and immersed in the radioactive solution, and another experiment of a direct contact batch system without membrane separation. The experiments also varied with respect to the level of caesium isotope contamination, with initial radioactive concentrations of approximately 30 kBq/l and 90 kBq/l, respectively. Changes in 134Cs radioactivity concentration were monitored in solution over time by liquid scintillation counting.
The results demonstrate the uptake kinetics, equilibrium conditions, and middle-term sorption stability. The effectiveness of sorption was influenced by the ionic composition of the water matrix, particularly for salt water. However, in the case of this most demanding matrix, the removal efficiency was approximately 80%, while under reference conditions (deionised water) the equilibrium point was 90%. On the basis of the moderate decrease in the efficiency of caesium isotope removal, it is possible to conclude that the material has good selectivity and great potential for use in environmental decontamination.
The work was created as a result of research project no. 2021/43/B/ST10/00632 financed by the National Science Centre.

Speaker: Prof. Katarzyna Szarłowicz (AGH University of Krakow Faculty of Energy and Fuels Department of Nuclear Energy and Radiochemistry al. A. Mickiewicza 30 30 – 059 Krakow)

6:00 PM A study on the analysis of ¹⁴C activity in biological samples in Taiwan

In this study, a dry decomposition method combined with carbon dioxide absorption was employed to analyze the activity of 14C in biological samples. Samples were lyophilized, pulverized, and combusted in a tube furnace to generate CO2. The evolved gas was sequentially absorbed by alkaline solution and precipitated as calcium carbonate (CaCO3) using calcium chloride. The precipitate was then acidified with hydrochloric acid to regenerate CO2, which was captured in a carbon-trapping cocktail. Final activity was determined by mixing the absorbent with a scintillation cocktail and measuring via a Liquid Scintillation Counter (LSC). Different types of fish were selected from local market in Taiwan for 14C analysis. The survey results showed that 14C activity of fish ranged from 182.7 to 268.8 Bq/kg-C, with a recovery rate of approximately 74.1%. The observation that 14C concentrations in marine organisms is consistent with established international literature.

Speaker: Liang-Yu Tao (Radiation Monitoring Center, Nuclear Safety Commission, Kaohsiung City 833172, Taiwan)

6:03 PM High-Resolution Environmental Radiation Baseline for Nuclear Emergency Preparedness in Hanoi (Vietnam)

A comprehensive radiological baseline is essential for strengthening national preparedness against potential transboundary nuclear incidents. This study establishes a high-resolution environmental radiation database for Hanoi, Vietnam. Radiation indicators—including ambient gamma dose rates in the air and the activity concentrations of primordial radionuclides ($^{238}\text{U}$, $^{232}\text{Th}$, and $^{40}\text{K}$) in soil and sediment—were systematically measured. The survey methodology, employing in-situ gamma dosimetry and laboratory-based high-purity germanium (HPGe) gamma spectrometry, adhered to both national and international standards.The mean gamma dose rate in the air for Hanoi was determined to be $0.068\text{ µSv/h}$. This value is consistent with both the national average for Vietnam and the global average reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The mean activity concentration for $^{238}\text{U}$ was $40.83\text{ Bq/kg}$ in Hanoi, while for $^{232}\text{Th}$, the concentration was $60.92\text{ Bq/kg}$. Notably, $^{40}\text{K}$ showed elevated levels at $583.61\text{ Bq/kg}$.The results indicate that regional radiation levels fall within the normal range of the natural background, with spatial distributions influenced by underlying geology and anthropogenic activities, particularly the elevated $^{40}\text{K}$ concentrations in agricultural areas. This dataset provides a critical and definitive baseline for distinguishing natural radiation variations from potential future radiological contamination, thereby enhancing Vietnam's nuclear emergency preparedness capabilities.
Keywords: Gamma dose rate, $^{238}\text{U}$, $^{232}\text{Th}$, $^{40}\text{K}$, Environmental radioactivity, Emergency preparedness, Hanoi.

Speaker: Tuan HOANG (Thu Dau Mot University)

6:06 PM Radiological Characterization and Indoor Health Risk Assessment of Fly Ash-Based Building Materials of Some Power Plants in Vietnam

This study assesses the radiological risks of using fly ash from major Vietnamese coal-fired power plants as a supplementary building material. Using HPGe gamma-ray spectrometry, the activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were quantified to calculate internationally recognized hazard indices and model indoor radon exposure scenarios. Results revealed significantly elevated ²²⁶Ra and ²³²Th levels. Notably, four of six samples exceeded the Activity Concentration Index regulatory limit of unity (TCXDVN 397:2007), and two samples exceeded the internal hazard index limit. The maximum calculated annual effective dose reached 1.545 mSv/year, surpassing the ICRP's 1 mSv/year public limit, with a corresponding Excess Lifetime Cancer Risk up to 5.20 × 10⁻³. These findings demonstrate substantial radiological heterogeneity among sources and underscore the critical need for mandatory screening and a risk-based classification framework in Vietnam.
Keywords: Fly Ash; NORM; Radiological Hazard; Radon; Building Materials; Vietnam; Gamma Spectrometry; TCXDVN 397:2007

Speaker: Tuan HOANG (Thu Dau Mot University)

6:09 PM Neutron activation analysis for assessing potential use of recycled construction and demolition wastes as agricultural remineralizers

Construction and demolition waste (CDW) is a complex combination of materials, including concrete, mortar, tiles, bricks, and ceramic flooring, representing approximately 50% of urban solid waste in medium and large cities. The final disposal of these materials constitutes a serious environmental problem, with a high incidence of illegal dumping, triggering studies on recycling and reuse processes. Recycled construction and demolition waste (CDW-R) can be reused as soil remineralizers, an alternative aligned with the principles of the circular economy, which allows for the reduction of the extraction of natural raw materials, in line with the Sustainable Development Goals (SDGs) of the United Nations' 2030 Agenda. Remineralizers are materials of mineral origin, generally volcanic or silicate rocks, applied to the soil to improve its physicochemical properties and biological activity, with a long-term effect to promote plant growth. Brazilian legislation (IN5/2016) specific to soil remineralizers limits maximum values for potentially toxic elements such as As, Cd, Hg, and Pb, as well as minimum levels of CaO, K2O, and MgO. Sampling campaigns of recycled construction and demolition waste were carried out in recycling companies in different regions of Brazil. The chemical characterization of these materials was carried out using neutron activation analysis (NAA) technique. Analytical portions of 200 mg were placed in high-purity polyethylene capsules, along with certified reference materials used for analytical quality control, and irradiated under a thermal neutron beam in the IEA-R1 nuclear research reactor (IPEN/CNEN), in São Paulo. At CENA/USP, induced radioactivity was measured by high-resolution gamma spectrometry using hyperpure germanium detectors with 50% relative efficiency at the 1332 keV photopeak of ⁶⁰Co. Spectral deconvolution and mass fraction calculations were performed using Quantu software, based on the k0 method. Twenty-two chemical elements - As, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Na, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, and Zn - were determined in all samples. The results indicate that the recycled construction and demolition waste have a chemical composition compatible with agricultural use as remineralizers and reinforce the potential of NAA as an analytical tool to assess the quality and safety of these materials.

Speaker: Mr Luiz Antonio Gonçalves de Azevedo (CENA - USP)

6:12 PM Radioactive Sleep Masks

Products claiming to use ‘Negative Ion Technology’ have become increasingly available in the UK via outlets such as eBay and Amazon. Many of these products are significant sources of ionising radiation and therefore, far from providing the advertised health benefits are in reality hazardous to health. This study investigated the radioactive composition of ‘negative ion’ sleep masks, marketed as “Energy Armor Serenity Masks”. The study has quantified the gamma radiation from the product and identified the key isotopes present. The sleep mask was deconstructed into four components and these were measured using Hidex Automated gamma-counting and gamma spectrometry. The components were immersed in water, dilute and concentrated nitric acid matrices to aid extraction of components. Naturally occurring radioisotopes including U-235, K-40 and daughter isotopes of the U-238 and Th-232 decay chains were quantified. Hidex gamma counting determined the rubber component to have the highest activity, and gamma spectrometry confirmed this part contained the highest masses of the investigated radioisotopes. Activity was also quantified in the remaining fabric, foam and elastic components, in comparatively lower amounts.

Speaker: Dr Nick Evans (Nottingham Trent University)

6:15 PM Anthropogenic and natural radionuclides in tissues of the Wilson’s Storm Petrel (Oceanites oceanicus) breeding on King George Island (Maritime Antarctica)

Despite Antarctica’s geographical isolation and protection under the Antarctic Treaty, the continent remains a recipient of global radioactive fallout originating from past atmospheric nuclear weapons tests and other events, such as the burn-up of the SNAP-9A satellite Long-lived radionuclides, including Cs-137, Sr-90, and transuranic elements such as plutonium isotopes and Am-241 persist in the Antarctic environment and can be used as tracers of environmental transport processes and food chain transfer. On the other hand, Antarctic ecosystems are also influenced by naturally occurring radionuclides originating from radioactive decay series as well as from primordial radionuclides present in the environment. These radionuclides may enter food web through atmospheric deposition, seawater, and dietary intake, and their accumulation in biological tissues can provide additional information on the natural biogeochemical processes and element cycling in polar ecosystems.
In this study, we examined material from seven pellets of the south polar skua (Stercorarius maccormicki) containing remains of predated Wilson’s storm petrels (Oceanites oceanicus), a highly migratory pelagic seabird, breeding in the Antarctic and migrating to distant wintering areas in the northern Hemisphere. The pellets were collected in the breeding areas of the skuas around Admirality Bay on King George Island, South Shetland Islands. Pellets were separated into two fractions: 1) residues of feathers, 2) bones. This allowed for comparative analysis of radionuclide accumulation across tissue types. Radiometric analyses included gamma spectrometry for gamma-emitting isotopes followed by radiochemical sequential separation ending with, alpha spectrometry for uranium, thorium, plutonium isotopes, Am-241 and liquid scintillation counting determination of Sr-90.
Assessing radionuclide loads in meso-predators such as storm-petrels provides essential data on the current radiological state of the region and the potential impact of persistent contaminants on Antarctic biota. The study contributes to our understanding of the transfer and distribution of both natural and anthropogenic radionuclides within the Antarctic food chain.

Speaker: Mr Mikołaj Wielgat (The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland)

6:18 PM Radioactivity and radon exhalation in bedrocks and soils used in traditional architecture in korea

Since people spend more than 80% of their daily lives indoors, exposure to natural radiation in indoor environments can have a serious impact on human health and lead to global public health issues. Indoor radiation exposure levels are influenced by building materials and construction methods, as well as the geological characteristics of the bedrock and soil on which the building is constructed. Most building materials of terrestrial origin contain trace amounts of naturally occurring radioactive materials (NORM), consisting primarily of daughter nuclides produced from the decay chains of 226Ra, 232Th, and 40K. These three naturally occurring radionuclides emit gamma rays and cause external radiation exposure to the human body. Internal radiation exposure, on the other hand, is caused by radon (222Rn) and its short-lived decay products (214Bi, 214Pb, and 218Po), which are released from building materials into indoor air. Radon is a daughter nuclide produced by the alpha decay of radium, which is contained in building materials.
This study investigated the radioactivity concentrations of 40K, 226Ra, and 232Th in bedrock samples collected from various geological regions in Korea. Radioactivity concentrations in soil, which has long been widely used in traditional Korean architecture, were also measured. Furthermore, radon exhalation coefficients were investigated for these rocks and soils. Natural radioactivity and radon exhalation coefficients were measured simultaneously using gamma-ray spectroscopy, a relatively simple radioactivity measurement method.
The activity concentration of NORM in rocks and soil, as well as the radon exhalation coefficient, were found to be significantly influenced by the type and origin of the rocks and soil. The average radioactivity concentrations in the rocks were approximately 40 Bq/kg for 226Ra, 80 Bq/kg for 232Th, and 900 Bq/kg for 40K. The average radioactivity concentration in soils were approximately 45 Bq/kg for 226Ra, 100 Bq/kg for 232Th, and 830 Bq/kg for 40K. The average radon exhalation coefficient in rocks and soils was approximately 8% and 25%, respectively.

Speaker: Sang-Han Lee (Korea Research Institute of Standards and Science (KRISS))

6:20 PM Optimizing phytoremediation efficiency of soils from German nuclear facilities

Phytoremediation is an attractive method for decontamination of soils because of its versatility, eco friendliness and sustainability. It has the potential to reduce the volume of low-level contaminated soil significantly at comparatively low costs, which is of great interest, e.g., regarding the shutdown of German nuclear power plants in 2023. It is long known, that plants can take-up radionuclides from the soil to a certain degree, however in order to use phytoremediation economically the efficiency has to be increased. Therefore, a better understanding of the migration and accumulation of radionuclides from the soil into the plants and within the plants, i.e. from the roots to the upper parts, is essential. Here we present the results of pot experiments using excavated contaminated soils from two sites of the first nuclear reactors built in the former German Democratic Republic. The reactors were in operation for more than 20 years and shut down in the early 1990s, meaning that the soils were contaminated over decades and radioactive and chemical equilibria have been settled.
The soils from both sites are characterized by a high fraction of sand (90 – 99%) and contain significant amounts of activation and fission products as well as transuranic radionuclides, such as Co-60, Eu-152, Eu-154, Eu-155, Sr-90, Cs-137, Am-241 and Pu. The activity concentration in the clay and silt fraction is 10 times higher than in the sand fraction because of the high sorption capacity of clays.
Pot experiments were carried out, growing lucerne (medicago sativa) and sunflowers (helianthus annuus) on the contaminated soils, in a climate chamber with optimized growth parameters (i.e., daylight, temperature and humidity). After three months the plants were harvested, dried, ashed and digested in order to determine the activity of γ-emitting radionuclides by HPGe-detectors. Combining these results with the activities determined in the soil samples gives transfer factors (TFs) for lucerne of 0.24, and 0.31 for Co-60 and Cs-137, respectively. For sunflower transfer factors of 0.35 for Co-60 and 0.15 for Cs-137 were determined.
Furthermore, sequential extraction has shown that only ~50 % of the Cs-137 in the soils is bioavailable for the plants. In order to increase the bioavailability and potentially the transfer of radionuclides into the plants, biodegradable phosphonates are added to the soils, expected to significantly enhance the mobility of some radionuclides.
The focus of future experiments will lie on determining TFs for the transuranic elements (Pu and Am) and on increasing the bioavailability of radionuclides by adding phosphonates and fungi to the soils, to increase the efficiency of phytoremediation.

Speaker: Ninja Braukmüller

6:22 PM Radiostrontium Analysis using Barium Silicate-Based Sr sorbent I: Sorption Characteristics for Application in Seawater

[Introduction]
Radiostrontium is a critical target for environmental monitoring in nuclear emergencies due to its significant long-term health risk by accumulation in bones. The main isotopes, ⁹⁰ Sr (half-life 28.9 years) and ⁸⁹Sr (half-life 50 days), are pure beta emitters whose conventional analysis are complex, time-consuming, and require hazardous reagents. In this study, we investigated sorption characteristics of a Sr sorbent, for rapid and safe analysis of radiostrontium in seawater. The Sr sorbent, Pureceram MAq (Nippon Chemical Industrial Co., Ltd.; hereafter P-MAq), is a water-insoluble white powder. It has a particle size range of 5–125 $\mu$m (average 25 $\mu$m) and a complex structure of mixed crystalline and amorphous phases.
[Experimental]
A fixed amount of simulated seawater was prepared by acidifying with 0.1 M HCl and adding sulfate ions, and then ⁸⁵Sr or ⁹⁰Sr-⁹⁰Y was spiked. A certain amount of P-MAq was added to this solution, and was stirred for 4 hours. The fractional activity in the P-MAq and supernatant were measured with a NaI scintillation counter or a liquid scintillation counter (LSC). Additionally, recoveries of major elements in seawater (Na, Mg, K, and Ca) were measured with an ICP-AES. The sorption rates for Cs, Pb, Ra, and Ba were investigated using ¹³⁴Cs, ²¹⁰Pb, ²²⁸Ra, and ¹³³Ba, those were measured with a HP Ge detector. The effects of Ca (0–20 mM) and sulfate (0–25 mM) concentration on Sr sorption also investigate in different concentrations.
[Results and Discussions]
A Sr recovery of over 90% was obtained by stirring 150 mg of P-MAq in 100 mL of simulated seawater for 4 hours. Major elements in seawater, Na, Mg, K, and Ca showed adsorption rate below 2%. The adsorption rates of Cs and Y were 0.001% and 7.4%, respectively. On the other hand, Pb, Ra, and Ba showed high adsorption rate of over 98% due to formation of insoluble sulfates. Therefore, radionuclides such as ¹⁴⁰Ba require attention during post-accident monitoring. Though natural radioactivity, such as Pb and Ra, will be negligible for small volumes (50-100mL).
The results revealed that high Ca concentrations reduced Sr recovery. At typical seawater levels (9-12mM Ca), Sr recovery was 91-89%, compared to 98% without Ca.
On the other hand, the Sr sorption rate was almost 0% without sulfate ions. So that, Sr is presumed to precipitate as sulfate before substituting barium in sorbent to form strontium silicate.
To apply for environmental samples, ⁹⁰Sr and ⁸⁹Sr are measured using LSC or a low-background gas flow counter (LBC). In LSC, centrifuged P-MAq was mixed with scintillators. For LBC, P-MAq was collected on a filter by suction filtration. In this case, the sorbent mass is less than 75 mg to minimize the self-absorption, which restricts the sample volume to 50 mL. This method achieves a detection limit of 0.6 Bq L^-1 for ⁹⁰Sr with a 60-minute measurement for a 50 mL seawater sample. This sensitivity is 50 times lower than the permissible limit of effluent standard for wastewater (30 Bq L^-1)
[Conclusion]
We have proposed a safe and rapid method for detecting radiostrontium in seawater using P-MAq within six hours without using hazardous reagents. This method provides sufficient sensitivity not only for emergency monitoring but also for routine environmental surveillance to confirm safety around nuclear facilities.

Speaker: Dr Haruka Minowa (The Jikei University School of Medicine)

6:24 PM Determination of $^{129}$I in Natural Samples from the Czech Republic Using AMS

The long-lived radionuclide $^{129}I$ might be used as a tracer for assessing environmental contamination, estimating water age, and elucidating water circulation processes on Earth. Since $^{129}I$ is present in environmental samples at ultra-trace levels, highly sensitive analytical techniques are required for the accurate determination of its isotopic ratio with the stable isotope $^{127}I$. However, the ratio is not actively monitored in the Czech Republic, and the environmental background values for the country are unknown. Therefore, we address the existing data gap by developing an effective methodology to support future monitoring efforts. The radionuclide is predominantly generated by the fission of $^{235}$U in nuclear power plants. Moreover, the amount of $^{129}I$ in the environment has increased due to global nuclear fallout from major nuclear events, among which the most significant for the Czech Republic were nuclear weapon tests and the Chernobyl accident. Iodine is very mobile in the environment and is difficult to measure consistently due to its highly variable speciation. Nevertheless, by combining accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICP-MS), we can effectively determine the ratio of $^{129}I$/$^{127}I$. Hence, here we present our progress towards analyzing the ratio of $^{129}I$/$^{127}I$ in natural samples by MILEA AMS and ICP-MS collected at selected sites in the Czech Republic.

Speaker: Vít Mareš

6:26 PM Sorption of Cs(I) on Czech bentonite BCV_2017 under synthetic groundwater conditions

The sorption behaviour of Cs(I) on Czech Ca–Mg bentonite BCV_2017 was investigated under conditions relevant to the engineered barrier systems in deep geological repositories. Batch sorption experiments were performed in synthetic groundwater SGW2 of Ca-HCO$_3$ type using natural bentonite and bentonite samples altered at 95 °C in 1 mol L$^{-1}$ NaCl, KCl, MgCl$_2$, or SGW2. The effects of contact time, solid-to-liquid ratio, initial radionuclide concentration, and bentonite alteration were evaluated.

Kinetic experiments showed that Cs(I) uptake reached apparent equilibrium rapidly, between sample preparation and the first sampling point after 0.9 days. Based on these results, a conservative contact time of 72 h was selected for equilibrium experiments.

Cs(I) sorption showed pronounced nonlinearity, indicating heterogeneous sorption sites and gradual site saturation. The experimental data were interpreted using distribution coefficients and fitted by linear, Freundlich, Langmuir, and two-site Langmuir models. The two-site Langmuir model provided the best fit according to the lowest WSOS/df values. The effect of solid-to-liquid ratio was statistically significant, although its practical impact was limited. Alteration of bentonite affected Cs(I) uptake mainly in the low-concentration range, whereas at higher concentrations, the isotherms of individual bentonite samples tended to overlap. Distribution coefficient values for Cs(I) were generally in the range of 10$^2$–10$^4$ L kg$^{-1}$, in agreement with previously published data.

The results confirm the strong retention of Cs(I) by BCV_2017 bentonite and show that thermal and chemical alteration can influence radionuclide uptake, particularly at low aqueous concentrations. These findings contribute to the assessment of Czech bentonite as a radionuclide-retaining material in engineered barrier systems.

Speaker: Erik Marenčák (CTU in Prague)

6:28 PM Determination of 236U in aqueous and other environmental samples from the area of the Czech Republic

The anthropogenic uranium isotope ²³⁶U represents a valuable analytical tool for both qualitative and quantitative assessment of the environmental impacts of nuclear activities. It enables the characterization of associated emissions and nuclear materials, and, owing to the chemically conservative nature of uranium, it can also serve as a tracer for various natural processes. However, its determination in environmental samples is challenging due to its extremely low concentrations, placing high demands on analytical sensitivity. For most applications, these requirements are met exclusively by accelerator mass spectrometry (AMS), which has been operated in Řež u Prahy since 2022 as a joint facility of the Institute of Nuclear Physics, the Archaeological Institute of the Czech Academy of Sciences, and the Faculty of Nuclear Sciences and Physical Engineering at CTU.

Until recently, ²³⁶U levels had not been systematically mapped across the Czech Republic. In response, initial sampling and analysis have been conducted in collaboration with the Department of Nuclear Chemistry (FNSPE, CTU) and the T. G. Masaryk Water Research Institute. Environmental samples were collected from selected locations, including subsurface water from boreholes, surface waters, and sediments, with a particular focus on the Vltava River basin and the area surrounding the Temelín Nuclear Power Plant. Additional materials such as uranium ore, iron, and demineralized water from various sources were also analyzed.

Ongoing research within this project includes the mapping of ²³⁶U and ¹²⁹I distributions at selected sites across the Czech Republic, taking into account both historical and current potential emission sources. A key objective is the development and validation of a comprehensive methodology to ensure reliable monitoring of these anthropogenic radionuclides.

This research is co-funded with state support from the Czech Technology Agency under the SARA project (SQ01010334), Environment for Life 2 Programme. The infrastructure of the AMS laboratory built under the RAMSES project was used in the research realization.

Speaker: Tomáš Prášek

5:15 PM → 6:30 PM Radiation Chemistry: Poster session

5:15 PM First studies of Bis-Ethoxy BtzPhen ligand for the CHON compliant AmSel Process

Advanced partitioning strategies are essential to enable sustainable closed nuclear fuel cycles and reduce the long-term radiotoxicity of spent nuclear fuel. Among these strategies, the AmSel process targets the separation of americium and curium. This represents a key step for advanced management strategies, as curium exhibits high neutron emission and decay heat, imposing stringent safety measures, while americium dominates long-term radiotoxicity in high-level waste. Despite their different behaviors, chemical similarity in the trivalent oxidation state makes their separation highly challenging [1].

Hydrometallurgical approaches exploit reverse selectivity: TODGA in the organic phase extracts lanthanides and curium, while americium is retained in the aqueous phase through a selective hydrophilic ligand. To address industrial and environmental constraints, CHON-compliant extractants are of particular interest. CHON ligands reduce secondary waste generation and allow solvent destruction by incineration. Moreover, advanced partitioning processes are carried out under high radiation fields, where radiolytic solvent degradation can strongly influence extraction efficiency and long-term process reliability. Previous AmSel studies mainly relied on sulfonated BTBP extractants, which, although providing good selectivity, showed limited compliance with CHON requirements and limited long-term stability [2].

In this work, bis-triazolyl phenanthroline-based ligands with bis-ethoxy (BTzphen) side chains are investigated. The role of the bis-ethoxy chains is examined to test their effect on extraction selectivity and radiolytic stability, while preserving the typical selectivity of nitrogen-donor phenanthroline systems.

To evaluate their suitability for application in the AmSel process, distribution ratios and separation factors were determined through batch solvent extraction experiments by varying ligand concentration, nitric acid molarity, and competing ions, using an organic phase based on TODGA diluted in a kerosene-octanol mixture. Preliminary extraction results show Am/Cm separation factors in the range of approximately 2.4-3.1 under optimized conditions.

The radiolytic stability of the ligand is evaluated through gamma irradiation experiments performed at absorbed doses from 10 to 100 kGy, representative of advanced reprocessing conditions. Degradation pathways are investigated using HPLC-MS analysis to identify radiolysis products and degradation mechanisms, while Raman spectroscopy is envisioned to monitor structural modifications of the ligands after irradiation.

The obtained results show that Am/Cm separation can be improved by the presence of this molecule, even when realistic lanthanide concentrations are introduced into the feed solution, indicating a potential for further optimization under process-relevant conditions.

This is work is funded by the European Union through the EURATOM research and training programme, project TRANSPARANT (Technological Research Action Necessary for Safe PARrtitioningand Nuclear Transmutation), Grant Agreement: 101166386.

Speaker: Margherita Grieco (Politecnico di Milano)

5:17 PM γ-IRRADIATION EFFECT ON DIFFERENT CLAYS' STABILITY

The purpose of this study is to assess structural changes in three clays following exposure to high gamma radiation. Clays' distinct physicochemical properties—particularly their sorption capacities—make them useful in a wide range of industries and basic research. It is essential to investigate the interactions between radiation and these materials to think about their potential applications in interdisciplinary and multidisciplinary research, such as chemical evolution, waste disposal, and the sorption of emerging contaminants.
For this study, samples of kaolinite, hectorite, and Na-montmorillonite clays were exposed to high gamma radiation dosages. We examined structural changes in clays using ATR-IR spectroscopy, X-ray diffraction (XRD), and electron paramagnetic resonance (EPR). Dihydroxylation, the development of paramagnetic defects, and vacancies in hectorite and kaolinite that marginally alter the crystal structure were the primary changes seen in the irradiation clays. Additionally, in hectorite and kaolinite, the irradiation caused Si-O splitting in the tetrahedral sheet.

Speaker: Alicia Negron-Mendoza (Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico)

5:20 PM Chemical effects of the irradiation temperature on the radiolysis of iron-pentacarbonyl ices

Fe(CO)5 is a promising precursor-candidate for ice lithography and a typical precursor for Focused Electron Beam Induced Deposition (FEBID) and Focused Ion Beam Induced Deposition (FIBID) processes. Therefore, its radiolysis has been studied in a plethora of model systems but its solid-phase radiation chemistry has not yet been described in depth.

In the case of isolated molecules, previous gas-phase experiments have shown that radiation-induced breakdown (which ultimately leads to the deposition of a metal layer) occur through the loss CO ligands. Unfortunately, the results obtained in the gas phase cannot be directly transferred to the bulk phase, as numerous other phenomena (e.g., energy transfer between ice and its environment, post-irradiation chemical processes, sputtering, etc.) are also have significance in the latter. In molecular ices irradiation temperature is an important factor which affects the crystal structure of the target, the desorption rates, and the accessibility of certain reaction channels.

In our research, we examined the behavior of Fe(CO)5 ice deposited on ZnSe substrates at temperatures of 20 K and 77 K under 1 MeV proton radiation. These experiments were carried out in the Ice Chamber for Astrophysics / Astrochemistry (ICA) facility, located at the HUN-REN Institute for Nuclear Research in Debrecen, Hungary. This experimental setup allows us to study the irradiation of variety of low-temperature targets with a multitude of different ionic projectiles over a wide energy range. The chemical changes of the targets were followed in situ during the irradiation via Fourier Transformed Infrared spectroscopy, meanwhile the desorbed gases were analyzed by a quadrupole mass spectrometer.

Our experiments showed that CO molecules accumulate in both systems as the result of irradiation. This accumulation was particularly interesting at 77 K, as this temperature is well above the usual desorption temperature of CO. The formation of CO2 was also observed in both systems indicating the secondary fragmentation of the products. At 20 K peaks associated with other oxides containing longer carbon chains also appeared. We observed differences in the relative abundance and formation dynamics of the different radiolysis products as a function of temperature. In both cases, we observed the appearance of absorption bands characteristic of bridging CO molecules as well, indicating the formation of multinuclear iron-carbonyl clusters.
By exploring the effects of temperature, our results could be potentially useful in assessing how Fe(CO)5 could be utilized as a precursor in ice lithography processes.

SUPPORTED BY THE EKÖP-25-3-1-DE-399 UNIVERSITY RESEARCH SCHOLARSHIP PROGRAM OF THE MINISTRY FOR CULTURE AND INNOVATION FROM THE SOURCE OF THE NATIONAL RESEARCH, DEVELOPMENT AND INNOVATION FUND.

Speaker: Gergő Lakatos (HUN-REN Institute for Nuclear Research and University of Debrecen, Doctoral School of Chemistry)

5:23 PM Radiation Stability of CsPbBr3 polymer nanocomposites

All-inorganic cesium lead halide perovskite nanocrystals, notably CsPbBr3, are emerging as highly promising candidates for ionizing radiation detection. Their high atomic number, defect tolerance, and ultrafast decay make them ideal for deployment as nanoscintillators, particularly when embedded in scalable polymer matrices. However, their long-term stability under high-energy ionizing radiation remains a critical concern for practical application.
This study investigates the degradation mechanisms and radiation stability of CsPbBr3 nanocrystals embedded in various matrices (polystyrene, epoxy resin, polydimethylsiloxane and silicon) when exposed to X-ray and electron irradiation. Using a combination of photoluminescence (PL), radioluminescence (RL), PLQY, and EPR spectroscopy, we tracked the evolution of optical properties and radiation-induced defect formation.
Our results indicate that high-fluence electron irradiation induces measurable structural damage, particularly in epoxide and silicon matrices. Surprisingly, while standard optical emission properties quenched post-irradiation, the radioluminescence intensity exhibited an increase. Rather than a simple degradation pathway, these results suggest complex interactions between the surface and the polymer matrix, potentially driven by altered energy transfer mechanism. Remarkably, polystyrene host matrices demonstrated superior radiation hardness compared to alternative polymers. These findings provide essential knowledge for optimizing perovskite-polymer nanocomposites, paving the way for their integration into next-generation time-of-flight positron emission tomography (TOF-PET), computed tomography (CT), and high-energy physics detectors.
This work has been supported by OP SEC project no. VK02020047. The work has been done in the frame of Crystal Clear Collaboration (CCC)

Speaker: Magdalena Rusová (FNSPE CTU)

5:26 PM Solvent-Driven Radiolytic Transformation of HCB in Propan-2-ol under Gamma Irradiation

Hexachlorobenzene (HCB) is a chlorinated aromatic compound classified among POPs due to its high chemical stability and resistance to natural degradation. Because of its persistence and potential environmental toxicity, the development of efficient methods for the destruction of HCB remains an important research objective. Ionizing radiation represents a promising approach for the degradation of stable organic pollutants because it produces highly reactive species capable of initiating complex chemical reactions in solution.
In this study, the radiolytic transformation of hexachlorobenzene dissolved in propan-2-ol was investigated under gamma irradiation. Experiments were performed using a cobalt-60 radiation source, with absorbed doses reaching up to 170 kGy. The irradiation time was varied between 0.5 and 27 hours in order to monitor the chemical transformation of the compound under increasing radiation exposure. All experiments were conducted under controlled laboratory conditions without degassing the solutions, allowing the radiolysis of both the solvent and dissolved oxygen to participate in the reaction system.
After irradiation, the reaction mixtures were analyzed using GC–MS. This analytical technique enabled the separation and identification of compounds formed during the radiolytic process. Several transformation products were detected in the irradiated samples. Among the most significant compounds identified were 2,5-hexanedione, 1,1-diethoxypentan-4-one, methylpentachlorobenzoate, and 1-propoxy-2-propanol.
The formation of these compounds indicates that the degradation of HCB in propan-2-ol occurs through a series of radical-driven reactions involving both solvent-derived intermediates and transformation of the chlorinated aromatic substrate.
The evolution of the detected byproducts was evaluated by monitoring their chromatographic peak areas obtained from GC–MS measurements.
The data demonstrate that the formation of several products increases progressively with irradiation time, reflecting the gradual decomposition of the parent HCB molecule and the development of secondary reaction pathways in the irradiated solution.
These observations confirm that gamma irradiation effectively initiates the transformation of HCB in propan-2-ol. However, the diversity of products detected suggests that the degradation process proceeds through relatively non-selective reaction pathways. The solvent therefore plays an important role in determining the distribution of radiolytic products formed during the process. Further research should focus on investigating alternative solvent systems or reaction conditions that may promote more selective degradation pathways while minimizing the formation of potentially undesirable intermediates. Such studies may contribute to the development of more efficient radiation-based approaches for the remediation of environments contaminated with persistent organic pollutants.

Keywords: POPs, HCB, Gamma radiolysis, Nuclear energy, Environmental remediation

Guo, W., Ren, H., Jin, Y., Chai, Z., & Liu, B. (2024). The bioremediation of the typical persistent organic pollutants (POPs) by microalgae-bacteria consortia: A systematic review. Chemosphere, 355, 141852. https://doi.org/10.1016/j.chemosphere.2024.141852
Karimov, S., Abdullayev, E., Gurbanov, M., Gasimzada, L., & Feyziyeva, S. (2024). Gamma Irradiation-Induced Degradation of hexachlorobenzene in methanol: Kinetics, mechanism and Dehalogenation Pathway. Radiation Physics and Chemistry, 112288. https://doi.org/10.1016/j.radphyschem.2024.112288

Speaker: Prof. Muslum Gurbanov (Institute of Physics)

5:29 PM Challenges in the development of a novel composite material suitable for colorimetric detection of gamma radiation

Analog crystal dosimeters have been commonly used for detection of γ radiation for the last 50 years. However, these dosimeters are prone to degradation, show false positive responses and their external evaluation is expensive and unsuitable for sensitive information. Therefore, there is a need to develop an appropriate replacement. A new composite material suitable for colorimetric detection could bring solution to analog dosimeters' problems. There are several possibilities of colorimetric detection of γ radiation by composite materials. One of the options is based on the detection mechanism of older liquid dosimeters, such as the ethanol-chlorobenzene dosimeter. This is a widely used liquid chemical dosimeter which uses radiolysis of chlorobenzene and ethanol after the exposure to γ radiation, resulting in the products of the radiolysis forming hydrochloric acid. It is important that the concentration of hydrochloric acid produced is linearly proportional to the absorbed dose of γ radiation.
The original intention of this work was to prepare a composite material consisting of a solid polychlorinated organic substance dissolved in an organic solvent and an acid-base indicator, all which will subsequently be incorporated into a polymer matrix. Upon γ irradiation, the polychlorinated substance in a suitable solvent should be radiolyzed to form hydrochloric acid. As a result, a color transition of the indicator will occur. Substance 1,4-bis(trichloromethyl)benzene was chosen as solid polychlorinated organic substance, p-nitrophenol was used as the acid-base indicator and several common organic solvents used for the preparation of polymer matrixes were tested, namely methanol, ethanol, isopropyl alcohol, toluene and tetrahydrofuran. The samples were irradiated by γ radiation from the radionuclide 137Cs in the range of absorbed doses from 0 to 1000 mSv. The radiolysis process and the colorimetric response of the samples were periodically studied by ultraviolet, visible and infrared spectroscopy methods. The effect of the solvent on the radiolysis process was determined by two-factor ANOVA.

Speaker: Mrs Klára Fricová (Vysoká škola chemicko-technologická v Praze)

5:33 PM Investigating the capacity and damage of ion exchange resins upon irradiation at RMC’s SLOWPOKE-2 nuclear reactor

Ion exchange resins (IERs) are used extensively in nuclear reactors to maintain low levels of ions in the coolant and moderator loops. In this specific context, IERs from the purification system of the moderator of CANDU-type reactors are investigated. Upon service in the moderator loop, the IERs will eventually become contaminated with radionuclides and will need to be kept in safe storage before their eventual disposal. A common practice in reactors is to slurry the IERs after their service life into large tanks in reactor buildings at individual stations, or (in Ontario only) to transfer the IERs into steel containers (“liners”) for extended storage at a licensed wastes site. In all cases, the inventory of contaminated waste IERs has accumulated for decades, and continues to grow along with electricity production from power reactors.

Among the contaminants present on these IERs originating from the operation of CANDU-type reactors, Carbon-14 (C-14) is a key radionuclide, due to its long half-life (≈5,730 years) and its bioavailability. It has been estimated that in Canada alone, over 7000 m^3 of resin wastes containing >10 PBq (1 PBq = 10E15 Bq) of C-14 will require disposal by year 2062. This amount of C-14 is considered to be available for release, therefore inventory control during interim storage is of the utmost importance. Carbon-14 retention on resins rely mostly on the fragile and pH-dependent carbonate continuum (Resin-CO3 /HCO3 ↔ HCO3- ↔ H2CO3 ↔ 14CO2), which can potentially release gaseous 14CO2. Since resins are not designed for the long-term retention of C-14, chemical changes are likely to occur on IERs over decades of extended storage, particularly, the cumulative effect of radiation imparted on the resin matrix and exchange sites by C-14 and other radiocontaminants.

In this work, the effects of radiation on IERs are being investigated, followed by analysis for damage. Samples of nuclear-grade anionic IERs (Amberlite IRN-78, Purolite NRW-400) have been irradiated in the RMC SLOWPOKE-2 nuclear reactor under a neutron flux of 10E10 n cm-2s-1 for four irradiation times, that is, 5.5, 11, 20 and 33 hours. The irradiated resins were then analyzed for damage using two methods: (1) ion exchange capacity loss, and (2) leachables from resins, using a Total Organic Carbon (TOC) release test, modified from our earlier work. Preliminary results indicate a capacity loss of ≈30-35% for the Purolite NRW-400 resin after a 33 hour radiation exposure, whilst the capacity loss for the IRN resin was ≈18-20% under the same conditions. The TOC leachables release from irradiated resin samples generally increased with irradiation time by a similar magnitude for both commercial resins. These results (capacity loss and TOC release of leachables) from the full range of irradiations for the two nuclear-grade IERs will be presented in this work.

Speaker: Dr Francois Caron (Royal Military College of Canada, Kingston)

5:36 PM The influence of Tb3+ content on La1-x TbxF3 and Ce0,15La0,85-x TbxF3 properties

Rare-earth doped cerium-lanthanum fluoride nanoparticles have shown great potential for cathodoluminescent (CL) imaging [1] and possible application in X-ray photodynamic therapy [2]. Besides chemical stability or suitable size it is also essential to find optimal luminescent properties of these materials via tuning of cerium [1] and terbium content. This work focuses on composition-based changes in luminescence, specifically by varying Tb3+ amount.
In this work, terbium-doped cerium-lanthanum fluoride nanoparticles were prepared via sol-gel method. We studied changes in morphological and luminescent properties of obtained materials with respect to Tb3+ content. The materials were analysed by X-ray diffraction (XRD), X-ray fluorescence (XRF), radioluminescence (RL), photoluminescence (PL) and cathodoluminescence (CL) spectroscopy. RL spectra were used to determine the optimal amount of Tb to ensure the best luminescent performance.
In this study we determined the optimal amount of Tb in these nanoparticles for future applications.
[1] X. Lytvynenko, M. Urbanová, O. Lalinský, V. Vojta, J. Bárta, L. Prouzová Procházková and V. Čuba. Composition-Dependent Properties of CexLa0.95-xTb0.05F3 Nanopowders Tailored for X-ray Photodynamic Therapy and Cathodoluminescence Imaging. Radiation Measurements, Vol. 189, 107536, 2025. (doi: 10.1016/j.radmeas.2025.107536)
[2] K. Popovich, L. Procházková, I. T. Pelikánová, M. Vlk, M. Palkovský, V. Jarý, M. Nikl, V. Múčka, E. Mihóková and V. Čuba. Preliminary Study on Singlet Oxygen Production Using CeF3:Tb3+@SiO2-PpIX. Radiation Measurements, Vol. 90, 325-328, 2016. (doi: 10.1016/j.radmeas.2016.01.033)

This work has been funded by a grant from the Programme Johannes Amos Comenius under the Ministry of Education, Youth and Sports of the Czech Republic, project LASCIMAT, No. CZ.02.01.01/00/23_020/0008525. This work was also supported by the Ministry of the Interior of the Czech Republic, project number VK02020047 (within the OP SEC call).

Speaker: Marie Urbanová (Czech Technical University in Prague)

5:39 PM Advanced Fenton Oxidation of Simulated Spent Mixed-Bed Ion-Exchange Resins

Spent ion-exchange resins (SIERs) constitute one of the most volumetrically significant fractions of low- and intermediate-level radioactive waste generated in the nuclear industry. According to IAEA estimates, annual generation from operating nuclear power plants amounts to 3000–5000 $m^3$. Beyond their large volumes, these wastes are challenging due to their high organic content, which complicates storage and disposal, e.g., because of biodegradability, flammability, and incompatibility with direct encapsulation strategies. In this context, Fenton oxidation represents a promising treatment route, capable of degrading the organic matrix and reducing the final volume.
In the present work, an innovative Fenton-like process was developed. Rather than relying on an externally added catalyst, as in state-of-the-art processes, this strategy leverages iron intrinsically retained in the SIERs due to corrosion-derived Fe uptake. Simulated SIERs, loaded with a realistic mix of stable elements (Fe, Cr, Co, Ni, Mn, Cs, Sr, and B), were used to ensure surrogate waste representativeness and robustness of the process. Kinetic studies showed that, at operating pH, iron was released from the resin matrix and dissolved into the working environment. Once mobilised, Fe sustained the Fe(II)/Fe(III) redox cycle underlying the Fenton reaction responsible for $H_2$$O_2$ decomposition and HO· generation, without external catalyst addition. Process optimisation focused on acid requirements, oxidant-to-catalyst ratio, water input, and temperature transients over defined time windows. Following optimisation, the system exhibited a controlled degradation and thermal plateau, consistent with controlled $H_2$$O_2$ dosing and avoiding runaway exotherms.
Overall performance remained comparable to the state-of-the-art, while avoiding the added mass of an external catalyst in the final residue. Under the optimised conditions, the treatment achieved 98% reduction in total carbon with an 83% weight reduction ratio. Moreover, optimisation progressively reduced reagent demand relative to the initial conditions, leading to a 30% reduction in oxidant consumption and a 67% reduction in water demand. After treatment, the liquor was evaporated to dryness, and the contaminant inventory recovered as residue. Quantitative X-ray diffraction phase analysis showed that the residue was predominantly amorphous, with $H_3$B$O_3$ (sassolite) as the main crystalline phase, together with minor metal oxide and sulfate phases.
These results demonstrate the feasibility of a stable and efficient Fenton treatment for surrogate SIERs, in which Fe already present in the waste matrix acts as an in situ catalytic species, supporting oxidative treatment as a viable strategy for organic radioactive waste streams. Preliminary ongoing evidence indicates that the acidic residue can be incorporated into phosphatic-based geopolymers without apparent loss of matrix integrity. Future work will focus on scale-up and real-waste validation, together with further qualification of the conditioning route.
Acknowledgement: EURAD-2 is co-funded by the European Union under Grant Agreement No. 101166718.

Speaker: Eros Mossini (Politecnico di Milano)

5:15 PM → 6:30 PM Radiopharmaceuticals: Poster session

5:15 PM Experience with the production of ⁶⁸Ga‑ and ⁶⁴Cu‑labelled radiopharmaceuticals in BIONT

The development of radiopharmaceuticals labeled with positron-emitting radionuclides has significantly expanded the capabilities of molecular imaging in nuclear medicine. Among these radionuclides, gallium-68 (⁶⁸Ga) and copper-64 (⁶⁴Cu) have attracted considerable attention due to their favorable decay properties and compatibility with a wide range of targeting molecules. This abstract summarizes practical experience with the routine preparation, radiolabeling, and quality control of ⁶⁸Ga- and ⁶⁴Cu-labeled radiopharmaceuticals in a radio pharmacy setting.
Gallium-68 is typically obtained from a ⁶⁸Ge / ⁶⁸Ga generator, enabling on-site production without the need for a cyclotron. But in the centrum equipped with cyclotron the ⁶8Zn(p,n)⁶8Ga reaction can be used. For ⁶⁸Ga activity comparable to generator liquid targets are applicable. For higher activity now the solid target are used. Its short half-life (67.7 min) makes it well suited for labeling peptides such as DOTA-conjugated compounds used in PET imaging. In our experience, automated or semi-automated synthesis modules provide reliable and reproducible labeling yields with high radiochemical purity. Critical steps in solid targets production are metal impurity control, optimized buffer systems, and temperature-controlled complexation. Quality control procedures generally involve radio-HPLC or radio-TLC analysis to verify radiochemical purity and ensure compliance with pharmacopeial requirements.
Copper-64 (t½ = 12.7 h), produced mainly in cyclotrons via the ⁶⁴Ni(p,n)⁶⁴Cu reaction, offers complementary advantages due to its longer half-life, enabling delayed imaging and distribution to centers without on-site production facilities. It is commonly used with chelators such as DOTA, NOTA, to label peptides, antibodies, and other biomolecules. Our production workflow includes careful control of reaction conditions, purification when necessary, and comprehensive quality assessment to ensure stability and suitability for clinical application.
Overall, both radionuclides provide versatile platforms for PET imaging agents. Practical experience indicates that standardized production protocols, reliable synthesis modules, and rigorous quality control procedures are essential for achieving consistent radiochemical yields and ensuring patient safety. Continued optimization of labeling chemistry and production workflows will further support the clinical implementation of ⁶⁸Ga- and ⁶⁴Cu-based radiopharmaceuticals.

Speaker: Prof. Pavol Rajec (BIONT a.s. Bratislava)

5:18 PM NuCapCure - Development of innovative proton and neutron therapies with high cancer specificity by 'hijacking' the intracellular chemistry of haem biosynthesis

Glioblastoma multiforme (GBM) is among the most aggressive human cancers, where the current combination of surgery, radiotherapy, and chemotherapy yields only limited extension of patient survival. The NuCapCure project introduces a radically new concept for treating deep-seated tumours by synergistically combining protons, neutrons, and the intracellular biochemistry. The core idea is the production of boron cluster-bearing-photosensitisers (PSs) within the cells. This will lead to selective enrichment of tumour tissue with boron, while sparing healthy tissues.
Cells loaded in this way can subsequently be targeted through two complementary modalities: (i) proton-based treatment, combining classical proton radiotherapy, proton induced photosensitizer activation (proton dynamic therapy), and boron proton capture therapy (BPCT); and (ii) neutron-based treatment, integrating neutron induced excitation of PpIX and boron neutron capture therapy (BNCT). Both approaches rely on short range alpha particles generated directly inside the tumour, enabling high spatial precision and the elimination of infiltrative cells surrounding the primary lesion.
Research Centre Řež (CVR) plays an important role in the project in neutron related experimental work. LVR-15 is one of the few European research reactors with longstanding experience in both experimental and clinical BNCT, making it an ideal platform for advancing the neutron component of NuCapCure. CVR is responsible for developing irradiation configurations, performing dosimetric simulations, preparing biological setups, and—critically—irradiating cell cultures and animal models with thermal neutrons, which is essential for assessing the efficacy of boron modified compounds. In addition, CVR works closely with partner institutions, Charles University of Prague, National Centre for Scientific Research Demokritos in Athens and the University of Oslo, to optimize irradiation geometry, neutron transport, and the validation of biological responses. This collaboration enables evaluation of both neutron-induced PS activation and the specific contribution of boron neutron capture effects.
NuCapCure thus represents a unique fusion of synthetic chemistry, radiobiology, proton physics, and neutron technologies. Our work aims to develop a multimodal therapy with the potential to achieve truly curative outcomes for GBM and other deep-seated tumours, while simultaneously revitalising European infrastructure for advanced neutron based therapeutic approaches.

Speaker: Daniela Veselá (Research Centre Řež)

5:21 PM Preparation of terbium-161 labeled radioimmunoconjugates based on monoclonal antibodies

Radioimmunoconjugates combine the targeting specificity of monoclonal antibodies with the therapeutic effects of radionuclides. Terbium 161 has emerged as a promising candidate owing to its favorable decay properties, including β⁻ emission and conversion/Auger electrons.
The monoclonal antibodies used in this study were rituximab and bevacizumab. Rituximab is a chimeric monoclonal antibody directed against the CD20 antigen expressed on the surface of B lymphocytes and is established in the treatment of B‑cell malignancies, including non‑Hodgkin lymphoma and chronic lymphocytic leukemia. Bevacizumab is a humanized monoclonal antibody targeting vascular endothelial growth factor A (VEGF‑A), a principal mediator of angiogenesis, and has been approved for the treatment of several solid tumors, including colorectal, lung, and renal cell carcinoma.
The purified monoclonal antibodies were conjugated with two chelators, NHS-DOTA
and p-SCN-Bn-DOTA, in 0.2M bicarbonate buffer (pH 9,2). The reaction mixture was gently mixed and incubated at 37°C for 4 h. The immunoconjugates were then isolated
by size-exclusion chromatography with the yield of 70 %.
Radiolabeling of the prepared immunoconjugates was conducted in 0.2M acetate buffer under systematically varied experimental conditions. The effect of pH on labelling efficiency was systematically evaluated at pH 5, 6, and 7. Additionally, different molar ratios
of immunoconjugate to radionuclide were examined to assess their impact on radiolabeling yield and efficiency. The kinetics of the radiolabeling process were also investigated
to elucidate the rate of radionuclide incorporation over time. These studies enabled
the optimization of reaction parameters for efficient and reproducible radiolabeling
of the immunoconjugates.
Finally, in vitro stability tests as well as cell internalization study in human ovaria cancer cells (SK-OV-3) were performer for the prepared [161Tb]DOTA-bevacizumab.
The radioimmunoconjugate was incubated in phosphate-buffered saline (PBS), fetal bovine serum (FBS), and human plasma at 37 °C, 21 °C, and 4 °C. The results showed excellent stability, with radiochemical purity remaining above 98% for all tested conditions. Although bevacizumab does not bind directly to the VEGFA receptor, it is internalized into cells via endocytic vesicles (Karpinska et al., 2023). This internalization mechanism was also observed for [161Tb]DOTA-bevacizumab, which was internalized into SK-OV-3 cells within 120 minutes, thereby delivering a radiocytotoxic payload. SPECT/CT imaging of [161Tb]DOTA-bevacizumab biodistribution in mice showed clear uptake in SK-OV-3 tumors 7 d p.i. as well as the antibody retention in heart and large veins mainly. These findings indicate a high degree of stability and suggest strong potential for future in vivo and clinical applications of the radioimmunoconjugate [161Tb]DOTA-bevacizumab.
This work was supported by AZV CR (NU23-08-00214) and CTU in Prague (SGS25/173/OHK4/3T/14).

Speaker: Barbora Brzková (Fakulta jaderná a fyzikálně inženýrská, ČVUT)

5:24 PM Optimization of the Preparation of [161Tb]Pertuzumab Radioimmunoconjugates

Certain cancers overexpress specific receptors that can be targeted by monoclonal antibodies, such as HER2, which is overexpressed in breast cancer and targeted by pertuzumab. Radioligand therapy builds on this concept by combining antibody specificity with radionuclide-mediated cytotoxicity for selective tumor irradiation.
Terbium‑161 has recently emerged as a promising alternative to lutecium‑177, offering enhanced therapeutic efficacy in small tumors due to its substantially higher emission of conversion and Auger electrons per decay.
This study investigates strategies for the conjugation of pertuzumab with bifunctional chelators, comparing lysine-directed nucleophilic substitution using NHS-DOTA with nucleophilic addition mediated by an isothiocyanate functional group (p‑SCN‑Bn‑DOTA). The conjugation reactions resulted in yields of 34 % for NHS-DOTA and 54 % for p-SCN-Bn-DOTA. The average number of DOTA moieties attached per antibody molecule, determined by MALDI-TOF-MS, was 9 and 12 for the respective conjugates. Furthermore, radiolabelling with Tb-161 was examined, and the stability of the resulting immunoconjugates was systematically evaluated.
Both conjugates were labelled with [¹⁶¹Tb]Cl₃ in 0.2 M acetate buffer (pH 6). The optimal reaction conditions, including molar ratio of conjugate to radionuclide and reaction time, were determined for each conjugate. The radiolabelling yielded 51 % and 99 % for the NHS-DOTA and p-SCN-Bn-DOTA conjugates, respectively, under optimized conditions.
In vitro stability studies were performed in phosphate-buffered saline (PBS) and fetal bovine serum (FBS) at room temperature and at 4 °C over one half-life of the radionuclide. The results demonstrate good stability of both DOTA–pertuzumab radioimmunoconjugates in PBS and FBS at 4 °C, with more than 95% of the activity remaining bound to the protein during the first half-life after radiolabelling. At room temperature, a higher degree of activity release was observed; however, more than 90% of the activity remained associated with the conjugate throughout the monitored period. SPECT/CT imaging of ¹⁶¹Tb-labelled pertuzumab biodistribution in tumor-bearing mice revealed very promising in vivo behaviour with the high accumulation in HER2-positive tumors (SK-OV-3) and no uptake in HER-2 negative tumors (MDA-MB231) 7 d p.i. combined with low accumulation in liver.
These results support the potential of radioimmunotherapy as a targeted therapeutic approach. Radiolabelled DOTA–pertuzumab with Tb‑161 demonstrates suitable stability in vitro, warranting further preclinical investigation. Additional studies are required to determine the clinical relevance of these radioimmunoconjugates.
This work was supported by AZV CR (NU23-08-00214) and CTU in Prague (SGS25/173/OHK4/3T/14).

Speaker: Tereza Janská (Katedra jaderné chemie, Fakulta jaderná a fyzikálně inženýrská, České vysoké učení technické v Praze)

6:30 PM → 7:00 PM Student Poster Competition: The Award Ceremony

8:00 PM → 9:15 PM Socials: Jam Band Session

9:30 PM → 10:30 PM Socials: Good Night Drink @ Singing Fountain

Fri, May 15

8:30 AM → 10:00 AM Nuclear Fuel Cycle: NFC 5

Conveners: Barbora Drtinová (CTU Prague), Susan Britz

8:30 AM Sustainable Waste Form Development: Solidification of Cobalt Captured Zeolite Waste into Geopolymer

Geopolymers have emerged as promising low-carbon cementitious materials for the solidification of complex radioactive waste streams, offering high mechanical integrity and chemical durability. Their low calcium content, distinct aluminosilicate chemistry, and low bound-water content render them inherently resistant to thermal, chemical, and irradiation-induced degradation. In parallel, zeolites are widely employed in the nuclear industry for selective radionuclide separation, decontamination of radioactive effluents, post-accident remediation, and as functional components in waste treatment and immobilization matrices.

In this study, the physico-mechanical properties of metakaolin-based geopolymers were first investigated by incorporating commercial zeolite 4A at loadings up to 30 wt%. Non-radioactive cobalt (Co) was subsequently sorbed onto zeolite, and dried Co-loaded zeolite (30 wt%) was encapsulated within the geopolymer matrix. Pristine, zeolite-doped, and Co-loaded geopolymer specimens were characterized using XRD, BET, and SEM-EDS techniques. Mechanical performance and durability were evaluated via ASTM compressive strength testing and freeze–thaw thermal cycling, while chemical stability and leaching behavior were assessed using the ANSI/ANS-16.1 protocol.

XRD analysis revealed the persistence of the crystalline zeolite 4A phase alongside the amorphous geopolymer gel. Zeolite incorporation led to enhanced compressive strength, attributed to micropore filling and the provision of additional nucleation sites for geopolymer gel formation. Notably, all specimens exhibited compressive strengths exceeding the waste acceptance criterion of the Korea Radioactive Waste Society (3.45 MPa), both before and after the thermal cycling test. Zeolite-doped samples consistently outperformed pristine geopolymers in terms of mechanical stability. Furthermore, leaching tests demonstrated excellent chemical durability, with a leaching index of 12.6, significantly surpassing the commonly accepted threshold value of 6.0.

These findings demonstrate the strong potential of zeolite-modified geopolymers as durable waste forms for the safe immobilization of complex nuclear wastes, supporting sustainable and low-carbon radioactive waste management strategies. Further optimization of the metakaolin-to-zeolite ratio, zeolite loading capacity, and alkali activator composition is required to enhance long-term durability, reduce costs, and deepen mechanistic understanding.

Acknowledgements
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Climate, Energy & Environment (MCEE) of the Republic of Korea (No. RS-2023-00236697) and by the National Research Foundation of Korea (NRF) grant funded by the Korea Government Ministry of Science and ICT (RS-2025-02311305).

Speaker: Dr SAJID IQBAL (Korea Advanced Institute of Science and Technology (KAIST))

KAIST_ SAJID RadChem 2026-Oral.pdf

8:48 AM Impact of a chabazite‑rich zeolitite on the retention of ¹³⁷Cs, ⁶⁰Co, and ⁹⁹Tc in metakaolin‑based acid‑activated geopolymers

Abstract:
A crucial step within radioactive waste (RW) management is the conditioning of RWs inside a stable and durable waste form, capable of guaranteeing the long-term confinement of radionuclides. Geopolymers are promising alternatives to traditional cementitious materials for the conditioning of low-to-intermediate level waste, especially for challenging RWs, e.g. those containing high amounts of borates, sulphates, or organic compounds, which exhibit limited compatibility with cement. Alkali-activated geopolymers exhibit excellent cation retention capabilities, particularly for highly mobile fission products such as 137Cs+ which act as charge-balancing cations within the negatively charged aluminosilicate network. Conversely, phosphate-based geopolymers (PGPs), typically manufactured using phosphoric acid activator, possess a positively charged surface, hence they prove effective for the immobilisation of anionic species, e.g. 36Cl-, 129I-, or 99TcO4-. On the other hand, the confinement performance of PGPs for cations is significantly worse than their alkali counterparts, especially on the long-term.
The objective of this research carried out within the EURAD-2 partnership is to develop a PGP capable of confining both anionic and cationic species of interest for the nuclear industry, namely Cs and Co as cations representative of fission and activation products, and the pertechnetate anion. To this aim, the integration of a chabazite-rich zeolitite in metakaolin-based PGPs was investigated. Chabazite is a crystalline aluminosilicate with high cation-exchange capacity, exhibiting high selectivity especially for Cs+. Two PGP formulations were investigated, i.e. a metakaolin-based reference and a variant with partial substitution of metakaolin with the chabazite-rich zeolitite. Both formulations were spiked with 137Cs, 60Co, and 99Tc tracers and underwent a leaching test according to the ANSI/ANS-16.1-2019 protocol, as required by the Italian regulator. Similar tests were replicated using stable Cs and Co to evaluate whether substantial concentration variations affect the immobilisation of the contaminants. Notably, the leaching behaviour of Tc, introduced within the PGP matrix as 99TcO4-, was investigated for the first time. The leachates were measured by gamma spectrometry (137Cs and 60Co) and mass spectrometry (stable Cs, Co, and 99Tc) and the leaching rates were calculated. The studied matrices showed promising retention capacity with respect to the literature. In particular, the samples containing the zeolitite exhibited better Cs confinement. To better explain the outcomes of the leaching tests and discern possible degradation of chabazite due to the interaction with phosphoric acid activator, powder X-ray diffraction (XRD) analysis was employed to evaluate the main crystalline species in the PGP samples.
The findings from this work could be of interest in the development of PGP matrices capable of ensuring the long-term retention of radionuclides regardless of the ionic form in which they occur, paving the way for more effective and safer RW management strategies.

Acknowledgement: EURAD-2 is co-funded by the European Union under Grant Agreement No. 101166718

Speaker: Mr Fabio Fattori (Politecnico di Milano)

9:06 AM MgNa3H(PO4)2 sorbent for purification of wastewater from activated corrosion products of reactor structural materials

This work addresses the selective removal of Co from large volumes of aqueous waste generated during nuclear power plant (NPP) operation. Efficient removal of Co-60, a long-lived γ-emitting radionuclide, can reduce occupational exposure and complement conventional treatment routes such as evaporation.
Phosphate-based inorganic sorbents are attractive for radionuclide capture due to their structural stability, high density of sorption sites, and fast uptake kinetics [1]. In addition, the formation of low-solubility metal phosphate phases can improve long-term immobilization under disposal-relevant conditions.
Here, we investigate the recently developed designer glaserite-type MgNa₃H(PO₄)₂ as a candidate material for Co immobilization. The material exhibits an open, layered crystal structure and a close match between the ionic radii of Mg²⁺ and Co²⁺, which facilitates cation substitution within the phosphate framework and contributes to both high sorption capacity and selectivity [2,3].
We confirm rapid Co sorption kinetics, high Co uptake capacity, and strong selectivity in the presence of elevated Na, K, Mg, and Ca concentrations representative of NPP wastewater. Rapid sorption of Zn, Cu, Ni, and Mn was also observed. These elements are of particular relevance in NPP systems, as neutron activation produces long-lived or high-energy radionuclides, including Zn-65, Ni-63, and Mn-54.
To enable operation under flow-through conditions, MgNa₃H(PO₄)₂ was immobilized in a polyacrylonitrile matrix, providing a practical route toward implementation in dynamic treatment systems.
[1] Y. Xie et al., J. Water Process Eng. 71, 107266 (2025)
[2] C. Yang et al., Chem. Eng. J. 486, 150362 (2024)
[3] L. Zeng et al., Resour. Conserv. Recycl. 212, 108005 (2025)

Speaker: Ms Elizaveta Artiushova (PSI & UniBE)

9:24 AM The behaviour of Tc(I) in the environment: A study of the interaction of [Tc(CO)3(H2O)3]+ on minerals

Technetium-99 (99Tc) is the most common isotope of technetium. It is a pure beta minus emitter with a long half live (213 000 years), and it is of great relevance in radioecology, due to its high mobility and long-term persistence in the environment. 99Tc is a major fission product from 235U and 239Pu, and, thus, present in high-level radioactive waste. Additionally, the widespread medical use of 99mTc radiopharmaceuticals leads to 99Tc, which can enter the environment via wastewater discharges.[1]

The immobilization of pertechnetate (TcO4−) by reduction to Tc(IV) has been widely studied in the environmental field.[2–4] However, Tc can also occur in other oxidation states. In particular Tc(I) in the {Tc(CO)3}-core, can form in high-level radioactive waste in the presence of stabilizing ligands[5] and is also investigated as core for radiopharmaceutical applications.[6] Despite this, the environmental fate of Tc(I) remains poorly understood from a radioecological perspective. To adequately assess the potential mobility and bioavailability, there is a need for data on its interaction with minerals and microorganisms. This includes thermodynamic data (solid to liquid distribution coefficients, TcI complexation constants) and molecular information on formed Tc species.

This work focuses on sorption studies of [Tc(CO)3(H2O)3]+ on different types of minerals and spectroscopic studies to assess the molecular process of the interaction. We perform comprehensive sorption studies under changing parameters (pH, ionic strength or concentrations) and the analysis of the Tc-containing solid by XAS, NMR and vibrational spectroscopies.

The authors acknowledge the German Federal Ministry of Research, Technology and Space (BMFTR) for the financial support of the NukSiFutur young investigator group TecRad (02NUK072).

Speaker: Caroline Börner (Helmholtz-Zentrum Dresden-Rossendorf)

9:42 AM Radionuclide Sorption on Natural, Synthetic and Composite Sorbents

The sorption of radionuclides from aqueous systems, investigated using radiotracer techniques, is essential for understanding radionuclide–surface interactions relevant to radioactive waste management and environmental radiochemistry. The Laboratory of Sorption Methods, Speciation and Radionuclide Migration at the Department of Nuclear Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, focuses on the investigation of radionuclide–solid phase interactions, primarily employing radiotracer techniques combined with advanced material synthesis and characterization. The laboratory systematically studies a broad portfolio of sorbent materials, including natural inorganic sorbents such as bentonites, zeolites, and related clay minerals, as well as their chemically modified forms. In addition, composite materials (e.g., carbon–clay and mineral-based composites), biogenic sorbents, geopolymers, and selected synthetic materials (e.g., MXene-based materials) are investigated with respect to their sorption capacity. The research is conducted using several radioecologically important long lived radionuclides, including Cs-137, Sr-90, Tc-99 (fission products of U-235), and Co-60, Ni-63, Ba-133 (an activation products). Batch sorption experiments are performed to evaluate the effects of pH, contact time, sorbent dosage, analyte concentration, and competing ions, and the data are interpreted using sorption isotherm models and kinetic parameters. The presented work highlights the laboratory’s multidisciplinary approach and recent results obtained for newly developed materials.

Speaker: Marek Hupian (Department of Nuclear Chemistry, Faculty of Natural Sciences, Comenius University Bratislava)

8:30 AM → 10:00 AM Nuclear Analytical Methods: NAM 6

Conveners: Jan Kameník (Nuclear Physics Institute of the Czech Academy of Sciences), Myung Ho Lee (KRIST)

8:30 AM Spectroscopic Tools for Online Monitoring Across Various Solvent Extraction Systems

Nuclear fuel reprocessing is essential for closing the nuclear fuel cycle, enabling the recovery of fissile materials from radiotoxic fission products. Solvent extraction (SX), which transfers target elements from an aqueous phase to an organic solvent, is the most widely implemented method for UNF reprocessing.
Extraction efficiency depends on factors such as acid concentration, phase ratios, and extractant stability. These parameters are typically characterized through offline experiments under fixed conditions; however, process conditions often vary, significantly affecting performance. Real-time, in situ characterization is therefore critical for understanding SX behavior under operando conditions. Industrial SX systems—including mixer-settlers, centrifugal contactors, and pulsed columns—pose unique challenges for real-time monitoring.
This work presents the development of spectroscopic tools for online, real-time monitoring across multiple SX configurations. Techniques include ultraviolet-visible (UV-Vis) spectroscopy and Raman spectroscopy for directly measuring analyte concentrations, and tracking extractant degradation, respectively. We demonstrate real-time analyte concentration monitoring across mixer-settlers and centrifugal contactors, enabling calculation of interstage distribution coefficients, as well as quantification of tributyl phosphate (TBP) and its degradation product, dibutyl phosphate (DBP). Additionally, we report real-time monitoring of a pulsed-column system using a multi-modal sensor platform.
Advancing these capabilities will enable more efficient nuclear fuel reprocessing and support next-generation fuel cycle technologies.

Speaker: Justin Cooper (Idaho National Laboratory)

8:48 AM Feasibility study for the usage of 3D printed tools in a radiochemical laboratory

The usability of custom-made 3D printed tools for radiochemical work in the laboratory and hot cells was investigated. 1110 test specimen produced from 6 different materials were post processed in batches according to the manufacturers specified recommendations. For each material, five specimens from randomly selected batches were exposed to a variety of chemicals under controlled laboratory conditions. Two exposure conditions were examined with two different contact times. In the first setup, the test specimens were exposed to the chemicals directly, whereas for the second setup, the test specimens were placed above a bath of chemicals allowing only vapours to reach the test specimens. Both configurations were applied for 1 hour and 24 hours to evaluate the chemical resistance of the material under incidental and prolonged exposure. After initial inspection, the test specimens were sent to an external laboratory for tensile tests, which were performed according to the DIN EN ISO 527-2.

The tensile module of the exposed specimens was used to evaluate the chemical resilience and assess whether the 3D printed material could be suitable for the appliance in a radiochemical laboratory. The comparison between non-exposed specimens to the datasheets provided by the manufacturer revealed that factors such as print geometry and post processing apparently influence the final strength of some materials more than others. This trend could also be observed with the results of the five test specimens exposed simultaneously. Showing, that the easy handling during production and repeatability of quality strongly depends on the used material.

Throughout the tests, the most aggressive chemical for the 3D printed plastics was identified and significant deterioration was identified through long exposure of vapours.

Highlight:
• One material was identified which withstands all chemical environments and is applicable under radiochemical laboratory conditions.
• This material however needs special attention during the production and post processing to ensure ideal performance.
• Another material was identified which withstands all chemical environments but has a limited lifetime for the most extreme conditions.

Speaker: Patrick Haaß

Presentatie_3D_Haass.pptx

9:06 AM Strengthening Global Radioanalytical Reliability: An Integrated Metrological Infrastructure for Decommissioning, Environmental Monitoring, and Waste Characterization

Reliable radionuclide measurements underpin regulatory decision-making across the nuclear lifecycle. However, increasing matrix complexity in decommissioning waste and heightened demands for environmental surveillance have exposed persistent gaps in interlaboratory comparability and quality assurance.

To address these challenges, we established an integrated metrological infrastructure combining proficiency testing (PT) schemes and certified reference materials (CRMs) developed in compliance with ISO/IEC 17043 and ISO 17034. Homogeneity and stability assessments were conducted according to ISO 33405, and laboratory performance evaluation followed robust statistical methodologies defined in ISO 13528, ensuring traceability to the International System of Units (SI).

Within the Nuclear Fuel Cycle (NFC) framework, PT materials for metal and wipe matrices were designed to validate analytical methods for both NORM and anthropogenic radionuclides. Furthermore, concrete-based CRMs were produced to support quality control in complex decommissioning waste, particularly for difficult-to-measure (DTM) radionuclides such as Sr-90, Ni-63, Fe-55, I-129, and plutonium isotopes.

In support of Environmental Radioecology (RER), seawater PT schemes were implemented to assess laboratory readiness for emergency monitoring of Cs-137 and Cs-134, complemented by shrimp-based PT materials for radiological food safety verification.

By integrating advanced Radioanalytical Methods (NAM) with internationally harmonized quality standards, this framework strengthens analytical defensibility, enhances global comparability, and provides a scalable model for sustainable quality assurance in radioactive waste management and environmental protection.

Speaker: Dr Sang-Han Lee (Korea Research Institute of Standards and Science)

9:24 AM Improving the sensitivity of atmospheric ¹⁴C measurement by liquid scintillation counting through method optimization

In France, radiological environmental monitoring is conducted by several actors, including the Authority of Nuclear Safety and Radiation Protection (ASNR). The objectives of this monitoring are to improve knowledge of radiological levels and their temporal evolution in the environment, to assess the radiological exposure of both the population and ecosystems, to detect radiological anomalies as promptly as possible, and to ensure compliance with regulatory requirements by the nuclear industry and to inform the public about radiological conditions in France. In this context, 3H and 14C, the most released radionuclides in the atmosphere by nuclear facilities, are of particular interest for atmospheric monitoring. Moreover, 14C is also frequently measured in the framework of environmental research studies. The ASNR’s analytical laboratories oversee the determination of 14C activities in the atmosphere, among other radionuclides.

Several analytical methods allow the determination of atmospheric 14C activities. Among them, Liquid Scintillation (LS) technology is an accessible technique for many laboratories. Several preparation techniques are possible (e.g., direct CO2 absorption, BaCO3 precipitation and benzene synthesis). These approaches differ in terms of detection efficiency and achievable detection limit. Sample preparation using the BaCO3 precipitation technique is challenging but the simplicity of its implementation makes it a preferred procedure.

Atmospheric 14C gas and organic forms (mainly CO2 and CH4) are trapped in NaOH solutions with a specific 14C sampler bubbler (SDEC France). In our laboratory, 14C is separated from NaOH solution by BaCO3 precipitation. This precipitate is mixed with an adapted liquid scintillator before 14C activities determination by LS counting. The most challenging step consists on having a one-phase mixture of the liquid scintillator and the BaCO3 precipitate. This mixture must be clear enough to minimize the quenching and thus to have a consistent determination of 14C by liquid scintillation.

Some improvements in the method, i.e. ultrasonic agitation and the immobilization of the precipitate by a gel in the scintillation cocktail, effectively reduce detection limits, resulting in more precise and accurate measurements. This method was validated through comparison with measurements obtained via AMS and very low activity spiked samples. The detection limit was determined to be 0.12 Bq/L or 90 Bq/kg C while the decision threshold was estimated at 60 mBq/L or 45 Bq/kg C. Environmental 14C levels unaffected by nuclear industry, typically around 226 Bq/kg C nowadays, are now achievable with this method.

Speaker: Hugo JAEGLER (Autorité de sûreté nucléaire et de radioprotection (ASNR), PSE-ENV/SAME)

9:42 AM Tools for the radiochemist, from method development to calibration to tracers to proficiency testing

Radioanalytical results by your laboratory are expected to compare within stated uncertainty with peer laboratories. Complex sample matrices, low detection levels and spectral interferences are a few of the challenges faced. This presentation will briefly cover some of the tools available to radiochemists to meet their data quality objectives and retain accreditation to ISO 17025, demonstrating laboratory competence.

Selecting calibration standards and spikes traceable to national metrology institutes (NMI’s) forms the foundation of comparable results. Traceability to the SI unit, the Becquerel, as defined in ANSI N42.22, includes exchanges with NIST(US), PTB(Germany) and NPL(UK) within Eckert & Ziegler’s measurement assurance program (MAP).

Reference materials are often used in method development but may not match your needs. Eckert & Ziegler addresses this using the concept of reference samples, made fit for purpose by matching matrix density and when possible elemental Z constituents in ready to use, aliquots, where the entire sample is used, eliminating the need for costly homogenization. As an example of customization, Isotopes, such as plutonium, can be made refractory or soluble based on project scope.

Eckert & Ziegler continues to provide an expanding list of over 90 isotopes. We recently brought back Pu-236 as an option when co-separating plutonium and neptunium for alpha spectrometry. Alternatively, Pu-242 is available in high and low impurity grades. The higher impurity grade, approximately 11% Pu-238 alpha activity impurity, is suited for mass spectrometry or as a laboratory control spike, and can be purchased in higher activities, while the low impurity option provides 99.9% Pu-242 by alpha activity.

For alpha spectrometry calibration sources, we provide options for tri-nuclide electrodeposited discs. In the last 10 years, we’ve introduced Gd-148, 71.1-year half-life, 100% alpha decay at 3182.7 keV, as the low energy line with higher count rate than natural uranium (U-238 energy with 79% intensity at 4198 keV and 21% intensity at 4151 keV). The low specific activity of natural uranium limits the activity deposited to <4 Bq (200 dpm) total uranium activity to avoid self-absorption and poor spectral quality on a 24.1 mm diameter disc.

Participation in a proficiency test (PT’s) program designed around your sample matrices, analytes, detection limits and methods prove competence, as called for in ISO 17025:2017. Bringing together over 90 isotopes, organic and inorganic matrices and the possibility to introduce refractory actinides invites PT customization. Eckert & Ziegler’s ISO 17043:2023 accredited program assigns values based gravimetric transfer of master solutions directly from NMI’s or calibrated using instrumentation validated through our MAP program. The result has allowed support of emergency response exercises using fresh mixed or other fission products in a variety of matrices, even goat milk in the joint US/Canadian CM ’25.

Speaker: Mr Lawrence Jassin (Eckert & Ziegler Isotope Products)

10:00 AM → 10:30 AM Coffee Break

10:30 AM → 12:00 PM Environmental Radioactivity: RER 4

Conveners: Galina Lujaniene, Rainer Kadan (AGES)

10:30 AM Radionuclides transport with groundwater in Chornobyl exclusion zone: geochemical modelling coupled to sensitivity analysis

Migration of radionuclides (RN) in the underground environment is strongly dependent on geochemical conditions that influence aqueous speciation and sorption processes. Current studies of RN transport with groundwater from the engineered near-surface disposal facility (ENSDF) for radioactive waste (RW) located in Chornobyl exclusion zone (ChEZ) use sorption models based on constant values of distribution coefficients (K_d) that do not take into account changes in geochemical parameters (e.g. pH, E_h, concentrations of dissolved ions). This assigns large uncertainties to measured K_d values and thus contributes to unnecessary conservatism of safety assessments. Earlier developed mechanistic smart-K_d values approach, implemented in this study, provides an advanced alternative to the conventional K_d approach by describing the variable geochemistry more realistically. Improved understanding of K_d-driven parameters will allow to derive less conservative RW inventory limits of ENSDF under regulatory established dose limits for post-closure safety assessment.
To implement this global research objective, in this study an overall model of RN migration from ENSDF with groundwater was constructed and parameterized with two categories of data: site-specific (geophysical characteristics of sediments; representative minerals of ChEZ sediments: quartz, orthoclase, kaolinite, montmorillonite, illite; chemical composition of groundwater; dose relevant RN: ¹³⁷Cs, ⁹⁰Sr, ²³⁹⁺²⁴⁰Pu, ²⁴¹Am and ²³⁷Np, and invariant (thermodynamic) data for aqueous speciation, mineral solubility and surface species for relevant element/mineral pairs.
To describe sorption by mechanistic, so-called smart-K_d values, thermodynamic datasets were developed and used for calculations:
1) surface complexation model (SCM) parameters:
- for quartz, orthoclase and kaolinite: diffuse double layer model;
- for montmorillonite and illite: non-electrostatic model;
2) ion exchange parameters: for montmorillonite and illite.
As SCM data for some element/mineral pairs were missing, chemical and mineralogical analogies were applied (e.g. U(VI) used as chemical analogue for Np(VI) and Pu(VI); montmorillonite used as min-eralogical analogue for kaolinite).
The sets of smart-K_d values (smart-K_d matrices) were obtained as a function of the following variable geochemical parameters: pH, E_h, SLR, [RN] (4095 combinations of parameters).
To quantify the contribution of each above-mentioned modelled geochemical parameter to K_d variability, a comprehensive variance-based global sensitivity analysis (SA) was performed. Based on the analysis of calculated values of sensitivity indices of the parameters, ranking of the significant parameters was carried out. The SA results demonstrate that smart-K_d values of Cs⁺ are predominantly driven by pH; K_d’s of Sr²⁺ are mainly influenced by [Sr²⁺]; K_d’s of Am³⁺ are the most sensitive to [Am³⁺] changes while pH and E_h have less impact; E_h is the most meaningful parameter defining sorption of Np and Pu whereas pH changes have less influence on their K_d values.
The calculated smart-K_d values will be further utilized in a transport simulation software tool to re-estimate maximum allowed specific activities of RN based on inverse modelling approach.

The authors gratefully acknowledge the funding provided by the Siebold Sasse Foundation (Leibniz University Hannover, Germany).

Speaker: Inna Iarmosh (Leibniz University Hannover / Helmholtz-Zentrum Dresden-Rossendorf)

10:48 AM Spatiotemporal distributions and mass budgets of artificial radionuclides (Cs-137 and Pu-239,240) in the seas surrounding Korea

In order to quantitatively evaluate and predict the behavior of the anthropogenic radionuclides, this study examined the spatiotemporal distributions and mass budgets of Cs-137 and Pu-239,240 in the seas surrounding Korean Peninsula (i.e., the East/Japan Sea, the Yellow Sea, and the southern sea of Korea) from 2018 to 2024. Surface activities of Cs-137 ranged from 0.56 to 2.43 mBq/kg, while those of Pu-239,240 ranged from 1.28 to 5.70 μBq/kg. Cs-137 showed a gradual decline over time, with surface distributions exhibiting slight spatial and temporal variations. The vertical distribution of Cs-137 showed surface or subsurface (< 100 m) peaks followed by a decrease with depth. In contrast, Pu-239,240 activities were depleted near the surface and increased with depth, displaying a distinct maximum at mid-depth (750 – 1000 m). Mass balance calculations suggest the negative inventory change rates (dI⁄dt) across all regions, indicating net losses of Cs-137 primarily due to radioactive decay and particle scavenging. The corresponding residence times of Cs-137 were 70.7 ± 1.0 years in the East/Japan Sea, 40.1 ± 0.7 years in the Yellow Sea, and 53.8 ± 1.2 years in the southern sea of Korea—all exceeding the radiological half-life of Cs-137 (30.17 years). These findings offer quantitative insights that can enhance future predictions of the variability in artificial radionuclide activities, such as Cs-137 and Pu-239,240, in Korean seas, where external inputs from surrounding regions play significant roles.

Speaker: Jaeeun Lee (Korea Institute of Ocean Science and Technology (KIOST), University of Science and Technology (UST))

11:06 AM Assessment of the actinide isotopic fingerprint and fractionation in soil samples from a nuclear research site

The new AMS facility HAMSTER (Helmholtz Accelerator Mass Spectrometer Tracing Environmental Radionuclides) at the Helmholtz-Zentrum Dresden-Rossendorf is dedicated to the analysis of actinides and other long-living radionuclides at ultra-trace levels. Due to the long history of the research campus at Dresden-Rossendorf as the major site for nuclear research in the former GDR, contamination of the construction site could not be excluded at least at the ultra-trace level relevant for various AMS applications. Thus, soil samples on HZDR‘s research campus have been collected and analysed for their $^{233/236}$U, $^{239/240/241/244}$Pu and $^{241}$Am content and isotopic ratios in order to assess possible contamination of the new accelerator building. Special attention is paid to isotopic signatures deviating from the expected global fallout signal, which may point to additional anthropogenic sources. In addition to this quantitative measurement approach some samples have been further processed to assess also the chemical fractionation of the actinides to study their transport and chemical association mechanisms.

Several soil samples next to the future HAMSTER facility were taken prior to the beginning of the construction. The samples were processed in the existing chemistry labs on HZDR’s campus and measured at two different AMS facilities (VEGA at ANSTO, and VERA at University of Vienna). The Pu concentrations and $^{24x/239}$Pu atomic ratios in the samples agree with values reported for global fallout due to atmospheric weapons tests in the 1950s and 60s. The $^{241}$Am/$^{241}$Pu ratios in the samples enable dating of the $^{241}$Pu influx which coincides with this time period.
Besides the transuranium elements, uranium isotopes (i.e. $^{233}$U and $^{236}$U) have been analysed in the soil samples. Interestingly, the measured $^{233/236}$U isotopic ratio is lower than expected for a pure global fallout signature. This may point to an additional source of reactor fuel whose origin has to be analysed with future investigations also using the HAMSTER facility on site.

The chemical fractionation of the actinides has been studied in one soil sample and an IAEA certified reference sediment sample (IAEA 385) using a sequential leaching technique to distinguish between exchangeable, carbonate-bound, Fe/Mn oxides-bound, organic-bound, and acid leachable fractions. Subsequently, a HF-parr bomb digestion step was added to access also refractory actinide oxides. Preliminary results of Pu fractions revealed that the majority of the plutonium is associated with carbonates in the sediment samples whereas organic material plays the major role in the soil sample. Interestingly, unexpectedly low $^{240/239}$Pu ratios were found in the refractory fraction in both the soil samples from HZDR as well as the sediment samples from the Irish sea. This may point to an influx of refractory plutonium oxide particles of weapons-grade Pu which has not been detected until now, as most sample treatment techniques for actinides do not use any HF treatment.

In summary, the actinide background on HZDR’s research campus mainly relates to global fallout signature with some hints for additional 236U background. A detailed analysis of the chemical fractionation of the actinides shows that most of the plutonium is bound to organic material. The analysis of the isotopic fingerprint reveals unexpectedly low $^{240/239}$Pu ratios in refractory fractions that is also present in a sediment sample from the Irish sea.

Speaker: Sebastian Fichter (Helmholtz-Zentrum Dresden-Rossendorf)

11:26 AM Danube monitoring of ¹³⁷Cs, ²³⁹Pu/²⁴⁰Pu, and ⁹⁰Sr in the years 2017–2024

The environmental monitoring program of the Danube was established in 1987 with a single sampling location at Vienna Nussdorf. In 1989 and 1992 the program was extended to three additional locations (Ottensheim, Wallsee, Greifenstein). The radioecological study was performed by the BOKU University – partly on behalf of the Austrian Federal Ministry of Agriculture, Regions and Tourism (BMLFUW). Thanks to this study, valuable long-term data of over 25 years are available. The sampling occurred continuously, in almost uninterrupted time series. One of the biggest goals of this long-term study was to assess long-term behaviour of the large-scale radioactive environmental contamination in the alpine ecosystem of the Danube.
However, in 2017 the Austrian Agency for Health and Food Safety (AGES GmbH) has been assigned by BMLFUW to continue the monitoring of the radioactivity in the Danube. Due to changed regulations at hydropower plants, on-site sampling was now longer possible. The sampling has been performed at the location of the run-of-river power plants by VERBUND AG, whereby a continuous, automated water sampling has been taken in monthly intervals.
Furthermore, the monitoring program changed by including plutonium isotopes and strontium-90 in the analysing program. These artificial radionuclides have been in the Chernobyl fallout as well as in the global fallout caused by nuclear weapon testing.
When the monitoring at AGES GmbH started, the radiochemical separation was performed sequentially with DOWEX™1x8 and Sr®Resin. However, a radiochemical method has been established for the simultaneous separation of plutonium isotopes and Strontium-90 using Sr®Resin by Triskem International. The measurement was performed by alpha-spectroscopy and liquid scintillation counting, respectively. To reach lower detection limits, monthly samples have been combined to two-month samples or yearly samples.
Here we present analytical results of over 400 samples and a detailed description of the separation of Plutonium isotopes and Strontium-90 using Sr®Resin.
These investigations were funded by the Federal Ministry of Agriculture, Forestry, Regions and Water Management of Austria.

Speaker: Krystle Elbers (AGES GmbH)

10:30 AM → 12:00 PM Separation & Speciation: SEP 6

Conveners: Sang-Han Lee (Korea Research Institute of Standards and Science), Viktor Goliáš (Charles University in Prague, Faculty of Science, Department of Geochemistry, Mineralogy and Mineral ressources)

10:30 AM Spectroscopic Insights into Cm(III) Coordination with Unsymmetrically Substituted Diglycolamides

Diglycolamides (DGAs) are an important class of extractants due to their modular chemical structure which enables systematic tuning of steric and electronic properties. They are used in americium selective extraction processes such as the AmSel process to facilitate the separation of trivalent ions from spent nuclear fuel. The TODGA/SO$_3$-Ph-BTBP system, for example, allows selective separation of Am(III) from Cm(III) and lanthanides with separation factors up to SF$_{\text{Cm/Am}}$ = 2.5. Substituting SO$_3$-Ph-BTBP with PrOH-BPTD reduces Am selectivity, whereas replacing TODGA with unsymmetrically substituted diglycolamides (UDGAs) enhances Cm/Am separation. These findings underline the pronounced sensitivity of extraction performance to subtle structural variations and emphasize the need for systematic studies of the underlying coordination chemistry.

We present a comprehensive spectroscopic study of Cm(III) complexation with a series of unsymmetrically substituted UDGA, called R-DdDGA (R = nPr, iPr, nBu and iBu; DdDGA = didodecyldiglycolamide) using time-resolved laser fluorescence spectroscopy. All investigated ligands form isostructural [Cm(UDGA)$_\text{n}$]$^{3+}$ complexes (n = 1-3). Data analysis demonstrates that both alkyl chain length and branching significantly affect complex stability. Propyl-substituted derivatives form more stable complexes than their butyl analogues, indicating that increased steric demand diminishes efficient ligand packing around the metal center. Shorter or suitably branched substituents mitigate repulsive interactions between coordinated ligands and thereby enhance stability. Additionally, the position of branching also plays a decisive role in complex stability. The α-branched iPr derivative forms complexes approx. 2.5 orders of magnitude more stable than those obtained with the β-branched iBu analogue. This observation aligns with extraction data showing reduced distribution ratios for β-branched ligands. In addition to steric effects, electronic contributions are likely involved. α-Branched substituents can transfer electron density more effectively to the amide group. This increases the donor strength of the coordinating oxygen atoms. Despite their strong binding affinity, UDGAs remain sufficiently flexible to enable ternary complex formation in the presence of coordinating anions. In nitrate media, for example, [Cm(UDGA)$_\text{n}$(NO$_3$)]$^{2+}$ (n = 1,2) species are observed. Overall, unsymmetric substitution not only modifies complex stability but also enables additional coordination modes that may be relevant for extraction processes.

Speaker: Thomas Sittel (Karlsruhe Institute of Technology (KIT))

10:48 AM Innovative and sustainable TODGA-based solvents: redesigning the organic phase for SNF recycling

Hydrometallurgical reprocessing of Spent Nuclear Fuel (SNF) relies on liquid–liquid extraction systems whose safety and sustainability are largely dictated by the organic diluent. While significant efforts have focused on ligand design, the diluent matrix remains a critical bottleneck due to toxicity concerns and incomplete compliance with the CHON principle. In recent years, research has aimed at moving beyond the separation effectiveness achieved with the conventional PUREX process, exploring advanced strategies capable of improving the overall sustainability. Innovative options are being developed that involve the co-extraction of Minor Actinides (MAs) together with Lanthanides (Lns), followed by their subsequent selective separation 1. Tetraoctyl Diglycolamide (TODGA), a benchmark ligand for the co-extraction of MAs and Lns from PUREX raffinate [2], is conventionally dissolved in a 95% hydrocarbon–5% 1-octanol mixture. Despite its widespread use, these formulations pose environmental and safety concerns, motivating the search for greener and more sustainable alternatives.
In this work, two strategies are proposed to redesign the organic phase based on TODGA without compromising the solvent performances. The first approach would bring circular economy principle into SNF advanced recycling, introducing waste cooking oil (WCO) as a renewable modifier instead of 1-octanol. The second strategy explores a paradigm shift through the complete substitution of the diluent with Deep Eutectic Solvents (DESs). Several DES formulations, obtained by tuning different components in various molar ratios, were screened to identify compositions effective in dissolving TODGA while ensuring long-term stability. The newly-proposed organic phases, i.e. 0.1-0.2 mol/L TODGA in kerosene + 5% WCO or in DES-based diluents, were comprehensively investigated by spiked liquid-liquid extraction tests and NMR investigations, to assess ligand solubility, acid compatibility, extraction efficiency under experimental conditions simulating the process environment (up to 3 mol/L nitric acid) and resistance to radiolytic and hydrolytic degradation (up to 200 kGy by gamma radiation, in contact with acid). Compared to the traditional solvent consisting of 0.1 mol/L TODGA in kerosene + 5% 1-octanol, both strategies led to new formulations with comparable extraction efficiencies, combined with remarkable stability under gamma irradiation and prolonged acid contact (Figure 1).
The integration of renewable feedstocks and the implementation of DES-based systems demonstrate that solvent engineering can significantly enhance the sustainability of SNF recycling without sacrificing performance, thus supporting the transition toward safer, greener, and more resilient nuclear fuel cycle technologies.

1 R. Taylor et al., Progress in Nuc. En. Volume 164, 2023, DOI: https://doi.org/10.1016/j.pnucene.2023.104837
[2] G. Modolo et al., Reprocessing and Recycling of Spent Nuclear Fuel, 2015, DOI: https://doi.org/10.1016/B978-1-78242-212-9.00010-1

Speaker: Massimiliano Federico Silvio Tentorio (Politecnico di Milano)

11:06 AM Assessment of TODGA degraded solvent in the AmSel process

The reprocessing of spent nuclear fuel is currently moving towards advanced cycles that contemplate the recycling of minor actinides, in particular americium (Am), as a strategy to minimise the radiotoxicity of the waste that must be stored [1]. Most of the recycling strategies developed to achieve an advanced closed cycle use the PUREX raffinate as a starting point. In this context, the separation of Am from the rest of the actinides, particularly from curium (Cm), has gained interest. Accordingly, the AmSel (Americium Selective) extraction process [2], which consists of three steps, has emerged. In particular, for the recovery of Am, the organic extractant TODGA and the aqueous ligand SO3-Ph-BTBP are used.

For the development of any extraction process, one of the main safety constraints is the resistance of the solvent to the highly radioactive environment and acidic conditions under which it must operate. Therefore, resistance studies of extraction systems are essential to assess the stability of the ligands and to identify their degradation compounds (DCs). From the perspective of long-term process operation in a future reprocessing plant, it is particularly important to understand the impact that these DCs may have on the extraction performance. Regarding TODGA stability, several authors have investigated its degradation and identified its corresponding DCs [3–4]. In fact, in one of our previous studies, the implications of these DCs on Am/Cm separation during the stripping step of the AmSel process were evaluated, leading to the conclusion that three of them could significantly affect the separation [5]. However, there is still a lack of information on their impact on the entire extraction process, considering all process steps and realistic operating conditions. This work aims to address this gap.

To this end, an organic solvent composed of TODGA was irradiated over several cycles up to moderate absorbed doses at the Náyade facility at CIEMAT using gamma 60Co sources. After each irradiation cycle, the composition of the TODGA solvent was analysed by HPLC–MS, quantifying the TODGA concentration and most of its DCs. To simulate the long-term operation of the process, after each irradiation cycle the remaining TODGA concentration was adjusted to its nominal value and the solvent was subsequently subjected to the next irradiation cycle. Finally, the impact of the degraded TODGA solvent, and consequently the presence of different DCs, was assessed in all steps of the AmSel process. This evaluation was carried out using highly active PUREX raffinate containing fission products and lanthanides, as well as actinide-spiked active solutions. Analyses were performed by gamma spectrometry, alpha spectrometry, and ICP-MS.

[1] Geist, Andreas, et al. Separation science and technology 56.11 (2021): 1866-1881.
[2] Wagner, Christoph, et al. Solvent Extraction and Ion Exchange 34.2 (2016): 103-113.
[3] Sugo, Yumi, Yuji Sasaki, and Shoichi Tachimori. Radiochimica Acta 90.3 (2002): 161-165.
[4] Sánchez-García, Iván, et al. EPJ Nuclear Sciences & Technologies 5 (2019): 19.
[5] Vacas-Arquero, Pablo, et al. Progress in Nuclear Energy 183 (2025): 105677.

Speaker: Iván Sánchez-García (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT))

11:24 AM Ab initio study of thermodynamic properties of ruthenium–nitrosyl system

For nuclear safety of spent fuel reprocessing plant, special attention must be paid to the volatile ruthenium species, particularly in case of the High-Level Liquid Waste (HLLW) storage tank accident scenario. The behavior of gaseous ruthenium therefore requires a detailed understanding of the successive stages of ruthenium volatilization and its chemical speciation, from liquid solutions up to residues. Up to now, it has been assumed that ruthenium tetroxide is the predominant volatile species; however, additional poorly characterized compounds, including ruthenium hydroxides (Ru-OH), oxo-hydroxides (Ru-(O)OH), and nitrates (Ru-NO3), have also been experimentally reported. A key unresolved question is whether RuO₄ is directly released from solution as the primary volatile species, or whether it is formed secondarily through the decomposition or oxidation of other dissolved precursors, such as nitrosyl–ruthenium complexes (Ru(NO)(NO3)3), which may instead constitute the initially and congruently released species. The present work aims to address this question by investigating, from a kinetic standpoint, whether such a gas-phase transformation is feasible under conditions relevant to accident scenarios in HLLW storage tanks.

Density Functional Theory (DFT) calculations were carried out using the TPSS hybrid functional in conjunction with augmented correlation-consistent basis sets (aug-cc-pVnZ, n = T, Q, and 5). Complete basis set (CBS) extrapolations were performed to obtain reliable energetic profiles. Starting from ruthenium nitrosyl complexes, the energetics of ligand dissociation were investigated in the gas-phase environments. The results indicate that the decomposition of nitrosyl complexes, as well as that of their primary by-products, does not lead to the formation of RuO₄ due to the presence of kinetically inaccessible or highly unstable intermediate species along the reaction pathway, even though the overall reaction is thermodynamically favorable.
These findings imply that, if RuO₄ is experimentally observed in the gaseous phase during HLLW processing, it must correspond to a species released congruently and directly from the liquid solution rather than being formed through secondary gas-phase transformations.

Speaker: LORIS GELIN

11:42 AM Volatilization of Ru to RuO4 and liquid-liquid extraction methods for its recovery from spent nuclear fuel

Isolating ruthenium from spent nuclear fuel is essential both for reducing the environmental and technological burdens of high-level liquid waste management, particularly during vitrification, and for recovering a highly valuable platinum-group metal. Ruthenium poses a considerable challenge during its separation from spent nuclear fuel. That can be attributed to its high yield, wide range of oxidation states, and tendency to form complex compounds. Our research focuses on developing a simple, promising, and well-characterized method for the recovery of ruthenium from nitric acid solutions simulating high-level liquid waste generated during the reprocessing of alternative spent nuclear fuel. The proposed procedure follows a two-step approach. First, the ruthenium, present as nitrosyl complexes, is oxidized with sodium periodate (NaIO4). Different compounds are formed – some are volatile, others are absorbed onto the walls of plastic ampules. After that, upon addition of the organic phase, the subsequent processes transport previously oxidised Ru forms into it. Through reactions with the diluent, Ru species can be transported to the interphase or even back to the aqueous phase.

The influence of trichloromethane or n-dodecane on distribution coefficients D-values is discussed. In addition to the proposed oxidation–reduction mechanism of ruthenium, the influence of key experimental parameters on the D and extraction efficiency (%E) was studied. Particularly, the concentration of the oxidizing agent, the oxidation time, the nitric acid concentration, and the phase contact time. The optimal NaIO4 concentration was determined to be 75 mmol·L-1. With increasing oxidation time, D values increased significantly, with higher values observed in the n-dodecane system (D up to ~800) than in trichloromethane (D ~60). The nitric acid concentration significantly affected the extraction; the highest distribution coefficients were generally observed at lower HNO3 concentrations. Kinetic experiments showed that equilibrium is reached within hours.

In contrast, in the n-dodecane system, D decreased with prolonged contact time, likely due to the reduction of RuO4 to RuO2 at the phase interface. Separation factors against Pd and Rh were also determined, yielding β(Ru/Rh) ~ 1300 and β(Ru/Pd) ~ 600 for n-dodecane, confirming the high selectivity of the method for ruthenium extraction from light platinum metals. Rather than proposing a direct alternative for industrial separation, this work provides a deeper understanding of the physicochemical behaviour of ruthenium in these complex systems. Elucidating these fundamental interactions is crucial for optimising existing separation technologies, which ultimately contributes to the future recovery of platinum-group metals and the reduction of the environmental burden associated with nuclear waste.

We gratefully acknowledge the HORIZON-EURATOM-2021-funded FREDMANS project (GA No. 101060800), SGS project (SGS24/148/OHK4/3T/14) funded by the Czech Technical University in Prague, and the EU and Czech MEYS funded project CROP (CZ.02.01.01/00/22_011/0008569) for supporting this research.

Speaker: Michael Seidel (FJFI ČVUT)

12:00 PM → 12:30 PM Socials: Closing Ceremony

12:30 PM → 2:00 PM Lunch