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Accelerator Mass Spectrometry – from archaeology to astrophysics and human DNA30m
The advancement of Accelerator Mass Spectrometry (AMS) some 30 years ago opened the possibility to detect long-lived radionuclides (both natural and man-made) through isotopic abundance measurements down to a level of ~10-16. It thus became possible to explore our world atom by atom in almost every section of the environment at large. Worldwide there are about 80 facilities in operation covering a large range of applications. The Vienna Environmental Research Accelerator (VERA) is an AMS facility for ‘all’ isotopes, based on a 3 MV tandem accelerator. The principle of AMS will be described with reference to this facility, and a few selected examples will be discussed.
A well-known application of AMS is radiocarbon (14C) dating in archaeology and other fields, where the counting of atoms as compared to the classical way of counting beta decays increased the 14C detection sensitivity by literally a factor of a million. This allowed us to date small samples of a very precious skull of the earliest humans in Europe, excavated some 100 years ago from the Mladec cave near Olomouc in the Czech Republic1, and preserved at the Museum of Natural History in Vienna.
At VERA we also started to explore areas of the nuclear landscape beyond any known isotope, such as the one around Z=114, N= 186, where an ‘island of stability’ for Super Heavy Elements (SHE) has long been predicted. If there are SHE isotopes with half-lives in the hundred-million-year range, it may be possible to find traces of them in natural materials left over from the formation of the solar system. We have conducted such an AMS search and will report on recent results2 and future experiments.
In the previous experiment we pursued experiments to find isotopes, which have been synthesized in stars before our solar system even existed.. The last example deals with events which happened during the last 50 years. Atmospheric nuclear weapons testing during the late 1950s and early 1960s led to a doubling of the 14C content in the atmosphere. After the Nuclear Test Ban Treaty in 1963, the rapid distribution of the excess 14C (‘14C bomb peak’) into the biosphere including humans allows one to study the formation of new cells in the human body after birth3. This can be accomplished by extracting DNA from millions of cell nuclei and measuring the 14C content in them. Brain cells, heart cells, and fat cells have been investigated so far, leading to new insights into cell birth dates and turnover times, respectively.
In addition to the biomedical application, the 14C bomb peak provides an important means to study the dynamics of the CO2 exchange between the atmosphere and the hydrosphere and biosphere, respectively. This is of utmost importance for a deeper understanding of our climate on earth.
1. Wild et al.: Nature 435, 332 (2005).
2. Dellinger at al.: NIM B (2009) on line.
3. Spalding et al.: Cell 122, 133 (2005).
(Vienna Environmental Research Accelerator (VERA), Faculty of Physics – Isotope Research, University of Vienna, Austria)
Electrochemical separation of actinides from molten LiCl-KCl on solid Al cathodes30m
To comply with the sustainability goals defined for innovative reactor systems, a waste minimization through recycling of all actinides is required and can be realised using a so-called Partitioning and Transmutation (P&T) concept inherent to the reactor systems. It is obvious that the corresponding fuel cycles will play a central role because an efficient and selective recovery of the key elements is mandatory.
One of the major goals is to develop and implement clean waste technologies using a global actinide management. For this purpose, advanced fuel cycle processes with full actinide fuel technologies and ultimate waste forms with a minimal content in actinides (< 0.1%) are required. This necessitates that Am and Cm can be selectively separated from lanthanide fission products, certainly the most difficult and challenging task in advanced reprocessing of spent nuclear fuel due to the very similar chemical behaviour of these elements.
The separation can be derived from aqueous or pyrochemical partitioning processes. Both have advantages and disadvantages and should be applied in a complementary way. In Europe, significant progress was made for both routes in international collaborations in the frame of the European research projects PARTNEW, PYROREP, EUROPART and ACSEPT.
Pyrochemical processes rely on refining techniques in high temperature (around 500°C) molten salt (e.g. LiCl/KCl eutectic). In nuclear technology, these processes are mostly based on electrorefining or on extraction from the molten salt phase into liquid metal. In the electrorefining process the fuel is anodically dissolved, releasing actinides and lanthanides mainly as MCl3 species into the molten salt electrolyte. The separation is based on electrodeposition of the actinides on a cathode leaving the fission products in the bulk.
The choice of cathode material onto which the actinides are deposited during electrolysis is essential. Molten Cd and Bi have been widely used because they are reactive electrodes, i.e they form stable alloys with the actinides. This alloying inhibits the re-dissolution of the electrodeposited trivalent actinides by a comproportionation reaction with not deposited An(III) in the salt melt and thus allows an efficient recovery of An metal. The redox potentials on solid cathodes show a difference in the reduction potential between actinides and lanthanides which is about 3 times higher than for liquid cathodes, improving obviously a separation of these two element groups. Solid Al cathodes unite both advantageous properties, i.e. the large difference in the electrodeposition potential and the reactivity to form alloys. Therefore we use Al electrodes for our electrochemical partitioning studies.
In view of a grouped actinide recycling, foreseen in the fuel cycles of new generation reactors, electrorefining experiments using a fuel with the overall composition U61Pu22Zr10Am2Ln5 were carried out. The metallic alloy was anodically dissolved in a LiCl-KCl eutectic and the actinides were co-deposited on Al cathodes as alloys, leaving more than 98% of the lanthanides in the salt phase. The results of a multiple-run electrorefining experiment without changing the salt bath, are very promising in view of a large-scale development of pyroreprocessing in advanced nuclear fuel cycles. They demonstrate that a grouped actinide recovery better than 99.9% are possible and therefore represent an important step towards achieving the sustainability goals of future reactor systems.
(European Commission, JRC, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe, Germany)
Comments on the correct interpretation of k<sub>0</sub>-factors and on the proper use of the SMELS materials30m
Recently plans were devised [IAEA CRP 2005-2009: “Reference Database for Neutron Activation Analysis”] for creating and publishing a library of k0-factors that are generated differently from the experimentally determined ones published and used in practice thus far [ADNDT, 85 (2003) 47]. For two reasons, we look at this anxiously. Firstly, when realizing that these “new” k0-factors will be based on values taken from (be it internationally evaluated and up-to-date) files dealing with data for decay (notably gamma ray emission probabilities) and activation (notably 2200ms-1 activation cross sections), it is clear that trackability and accuracy are likely to be jeopardized. Indeed, an evaluated cross section is (partially or fully) based on values that are experimentally measured via the “activation method”, thus requiring the introduction of gamma ray emission probabilities that are selected by the experimentalist. This implies that the link is broken when they are again combined with recently evaluated gamma-ray probabilities – whereby it is irrelevant whether the latter are in se more accurate than the ones introduced formerly. This means that the way of creating these “new” k0-factors is basically incorrect. Secondly, the release of the thus obtained k0 library, next to the one for actual use in the practice of k0-NAA (managed formerly by the INW/Gent – KFKI/Budapest, and in the future by the recently established k0 Nuclear Data Committee), would inevitably bring about confusion and ambiguity.
Also in recent years, we observed from published papers and from communications at conferences that the SMELS materials (Synthetic Multi-Element Standards) are not properly used for what they were developed for [NIMA, 564 (2006) 675]. Indeed, it is seen that the SMELS are systematically applied for the validation of k0-NAA carried out in a laboratory, whereas their real potential lays in the quality control of the implementation of the k0-standardization, notably with respect to the calibration of the irradiation facility and of the Ge-detector, including also the correction for dead-time in case of short-time NAA. Indeed, the three SMELS-types are doped with elements that give rise to (n,γ) activation with epithermal-to-thermal cross section ratios and emitted gamma-ray energies ranging from low to high (thus giving information on the correctness of respectively the neutron flux characterization and the detection efficiency determination), and (for SMELS-type I) with half-lives ranging from low to high (thus giving information on the correctness of dead-time correction). Regrettably, these built-in potentials of the SMELS are overlooked in nearly all cases described in the literature.
DrFrans De Corte
((em.) Ghent University and Research Foundation-Flanders)
Excitation functions of the <sup>231</sup>Pa(p,2n) and <sup>231</sup>Pa(d,3n) reactions - experiment as a feedback of model calculations30m
(Nuclear Physics Institute, Academy of Sciences of the Czech Republic)
Chemistry of the transactinides30m
Advanced methods that have been developed and applied to study the chemical properties of the transactinide elements in comparison with their lighter homologs are presented.These include thermochromatography, and isothermal chromatography in the gas phase as well as ion-exchange and reversed-phase liquid chromatography in the aqueous phase, liquid-liquid extraction, and electrodeposition. Latest applications of these methods to studies of the chemistry of the transactinides are shown.
From a systematic study of the anion-exchange behavior of Rf, it has been concluded that the properties of Rf in HCl and HNO3 solutions are similar to those of Zr and Hf [1-3]. However, in HF solutions, the fluoride complex formation of Rf is significantly different to that of its homologs [4-8]. In dilute HNO3/HF, the nitrate ion is the counter ion that removes the Rf hexafluoride di-anion more effectively from the binding sites of the anion-exchange resin than the Zr and Hf fluoride complexes. In strong HF solutions, it is the HF2- ion, that removes Rf much earlier from the anion-exchange resin than the much stronger fluoride complexes of Zr and Hf [6,7]. Chloride and fluoride complexation of Db has been studied in reversed-phase extraction chromatography with an aliphatic amine . Chelating of Db with alpha-hydroxyisobutyrate was shown to be much stronger than for tetravalent and trivalent metal ions . Sg has been eluted from a cation-exchange column as Sg oxyfluoride complex . In 0.1 M HNO3, hydrolysis of Sg is weaker than that of Mo and W . Successive deprotonation leads to a cationic species for Sg, while for Mo and W, neutral hydrolysed species are eluted from a cation-exchange column. In the gas phase, Sg was volatilized as SgO2Cl2  and as SgO2(OH)2 . Elements 107 and 108 were transported in the gas phase as BhO3Cl  and HsO4 . In , the highly volatile HsO4 was deposited on a thin layer of NaOH in the presence of water vapor, thus forming a salt in analogy to the formation of an osamate (VIII). This shows that HsO4, like OsO4, is an acid anhydride. Most recently, first chemical studies were performed with elements 112  and 114 . Element 112 in its atomic state was shown to be very volatile, but unlike radon, reveals a metallic interaction with a Au surface . Preliminary results on the volatility of element 114 in its atomic state indicate that it is a very volatile element with a weaker metallic interaction with a Au surface than 112 . This surprising result needs to be confirmed.
 H. Haba et al.,(2002).  R. Günter et al.,(1998).  H. Haba et al., (2007).  E. Strub et al., (2000).  A. Kronenberg et al., (2004).  H. Haba et al., (2004).  Y. Nagame et al., A. Toyoshima et al., (2004).  W. Paulus et al., (1999).  M. Schädel et al., (1992).  M. Schädel et al., (1997).  M. Schädel et al., (1998).  A. Türler et al., (1998).  S. Hübener et al., (2001).  R. Eichler et al., (2000).  Ch. E. Düllmann et al., (2002).  A. von Zweidorf et al., (2004).  R. Eichler et al., 2007).  R. Eichler et al., (2009).
Prof.Jens Volker Kratz
(University of Mainz)
Radionuclides in drinking water - an overview: The EU directive, analysis, the Austrian standard, geographical distribution, removal and waste problems30m
Drinking water is the most important food, therefore special care has to be taken for its purity. The European Union has issued a Directive on the Quality of Drinking Water, which also contains a chapter on radionuclides. The details will be discussed.
With rare exceptions only Naturally Ocurring Radioactive Material (NORM) is of importance for the dose from drinking water. NORM usually cannot be determined by putting a sample on the Ge-Detector. Radiochemistry is needed.
New methods have been introduced and the traditional measurement of Rn-222 and Ra-226 has been extended to other radionuclides like Ra-228, Po-210 and Pb-210.
The Austrian Standard on Compliance with the EU Indicative Dose will be presented and recommended to be used with country specific adaptions.
In this context the geographical distribution of radionuclide concentrations in drinking water are of importance and examples will be given.
Finally the question of purification of water arises. The results of a EU-project on removal of NORM (TENAWA) will be presented as well as the logical question of (radioactive) waste from the purification.
New nucleus <sup>277</sup>Hs: in between two islands of stability15m
The nuclear fusion reactions 244-Pu(48-Ca,3n)289-114 and 244-Pu(48-Ca, 4n)288-114 were studied at the new, highly efficient gas-filled recoil separator TASCA. The large number of thirteen observed decay chains assigned to 288-114 and 289-114 enabled reliable cross sections measurements. The highest cross section was 8.2 (+4.0 / -2.8) pb measured for the 4n evaporation channel. The new nucleus 277-Hs was observed. It decayed by spontaneous fission after a lifetime of 4.5 ms. Model calculations, which reproduce the properties of nuclides in the region around longer-lived deformed doubly-magic 270-Hs well suggest 277-Hs to be located near a minimum of shell stabilization between this island of deformed nuclei and the island of stability of spherical superheavy nuclei.
(Paul Scherrer Institute and Bern University, CH-5232 VILLIGEN PSI, SWITZERLAND)
Chemical identification of element 114 at TASCA15m
The newly built gas-filled separator TASCA, at the GSI Darmstadt has been successfully commissioned. TASCA was designed to study the physics and chemistry of the heaviest element and it has been demonstrated that TASCA is the most efficient device for the production of superheavy elements in complete fusion reactions with a 48Ca ion beam. Two experiments on the physics and chemistry of element 114, produced in the 244Pu(48Ca;3-4n)288,289114 reaction, were performed at TASCA in 2009 in the framework of the international TASCA collaboration. 17 decay chains from element 114 were detected. The decay properties of 288,289114 and the high cross sections reported by Oganessian et al.  have been confirmed. Here, we report on the results of the experiment on the chemistry of element 114 that was performed at TASCA in September 2009.
Evaporation residues (EVRs) of element 114 were produced in the irradiation of a 244Pu target (~ 580 ug/cm2) with 48Ca ions at an excitation energy of 42 MeV. The EVRs were separated in TASCA, which was operated in the Small Image Mode . They then passed through a 3.3 um Mylar window (30 x 40 mm2) into a Recoil Transfer Chamber (RTC) of 29 cm3 in volume made from Teflon. The atoms were thermalized in the RTC in a He/Ar gas mixture (7:3) and then flushed into the COMPACT detector , which was directly connected to the exit of the RTC. Two chromatography channels made from 32 pairs of PIN diodes covered with a thin gold layer were connected in series: the first one was kept at the room temperature, and the second one had a negative temperature gradient from +20 to -160C. This allowed efficient detection of chemical species with different volatilities: from non-volatile Pb to very volatile Rn. The distribution of Pb and Hg in COMPACT was measured in separate experiments with short-lived Pb and Hg isotopes that were preseparated in TASCA. For monitoring the detection system, a small amount of 219Rn was added to the carrier gas and was responsible for alpha particle background in spectra. No other peaks from alpha particles were found. Two decay chains from element 114 were detected: one from 288114 and one from 289114 produced in 4n and 3n evaporation channels, respectively. Both decays from element 114 isotopes were observed in the first detector channel, held at room temperature. From this observation, we can conclude that element 114 is less volatile than element 112 and more similar to Hg. This is in agreement with theoretical predictions  and contradicts previous chemical experiments with element 114 as performed by the PSI group at FLNR Dubna .
 Yu. Ts. Oganessian, J. Phys. G 2007, 34, R165-R242 (2007).
 A. Semchenkov et al. NIM B 266 (15), (2008).
 J. Dvorak et al. Phys. Rev. Lett. 97 242501 (2006).
 V. Pershina et al. J. of Chem. Phys. 131 083713 (2009).
 R. Eichler, submitted to Radiochim. Acta.
(Institute for Radiochemistry TU Munich)
Independent verification of element 11415m
Production of numerous superheavy elements (SHE) in 48Ca irradiations of actinide targets was reported by the Dubna Gas Filled Recoil Separator (DGFRS) group in past years . Independent verification of these observations has been of paramount importance, but confirmation experiments failed to produce SHE in 48Ca induced reactions. We report on the first successful independent verification of the production of element 114 in the reaction 48Ca(242Pu,3-4n)287,286114 at a center-of-target energy of 244 MeV. Two genetically correlated decay chains were observed during 8-day experiment at the Lawrence Berkeley National Laboratory's (LBNL) 88-Inch Cyclotron. Based on the observed decay properties these decay chains were attributed to decay of 287114 and 286114 produced in 3n and 4n channel, respectively. Implications of this observation on chemistry and physics of the heaviest elements will be discussed.
(Helmholtz Institute Mainz)
Element 114 chemistry and what is next?15m
Based on the order in periodic table, element 114 should be placed in the group 14, which includes such elements like C, Si, Ge, and Pb. It can be expected by the law of periodicity that E114 will reveal a more metallic behaviour than its lighter homologues. However, relativistic quantum chemical calculations predict different chemical behaviour, namely, higher inertness in comparison with lead [1-3]. In the present research an experimental determination of deposition temperature of element E114 on gold is presented.
During the present research in the irradiation of 242Pu with 48Ca (details see ) a decay chain was observed, which was assigned to the primary product of the nuclear fusion reaction – the isotope 287E114 (T1/2=0.5 s). A deposition temperature for this isotope of -88 °C was observed. This unusual first chemical observation of element E114 was confirmed switching to the projectile target combination 48Ca and 244Pu. The production of 288E114 and 289E114 are reported in the nuclear reactions 244Pu (48Ca, 4n) and 244Pu (48Ca, 3n), respectively . During this experiments two more decay chains, which were attributed to the isotope 288E114 were observed, fully confirming the first observation. A kinetic Monte-Carlo based model of gas adsorption chromatography  assesses the adsorption enthalpy (−ΔHads(Au)) from the observed deposition pattern of element 114 on the gold surface in the COLD at the applied experimental conditions as −ΔHads(Au)(E114) = 34±54(11) kJ/mol (95% c.i.). Recent relativistic density functional calculations predict the formation of a metallic bond between element 114 and gold . A semi-empirical macroscopic metal-metal adsorption model [7,8] predicts adsorption enthalpy of a metal-like element 114 on gold of −ΔHads(Au)(E114) = 183 kJ/mol. The adsorption enthalpy of a noble-gas like element 114 on gold surfaces was estimated to −ΔHads(Au)(E112)= 42±5 kJ/mol . The comparison between these theoretical values and our experimental result concludes the formation of a noble-gas like weak physisorption bond between atomic 114 and a gold surface in contrast to the expectations from the relativistic models and from empirical predictions. On a 95% confidence level element 114 is interacting weaker with gold compared to mercury. New possible experimental techniques pointed to investigation of chemical properties of super heavy elements will be discussed.
 Eichler, B. Kernenergie 19, 307-311 (1976) (in German).
 Seth M. et al. Angew. Chem. Int. Ed. 37, 2493-2496 (1998).
 Pershina, V. et al. J. Chem. Phys. in press, (2007).
 Eichler, R. et al. Angew.Chem. Int. Ed., 47, 3262-3266 (2007).
 Oganessian, Yu. Ts. et al. Phys. Rev.C 70, 064609 (2004).
 Zvara I. Radiochim. Acta 38, 95-101 (1985).
 Eichler, B. et al. Radiochim. Acta 33, 121-125 (1983).
 Eichler, B. Metal chemistry of transactinides. PSI Report 00-09,
Villigen (2000) , Volatilization properties of transactinides from metal
surfaces and melts (thermochemical calculation). In PSI Report 03-01,
Villigen (2002), ISSN 1019-0643.
 Eichler, R. et al. J. Phys.Chem. B 106, 5413-5420 (2002).
Vacuum thermochromatography - theory and Monte Carlo simulation15m
Vacuum Thermochromatography – Theory and Monte Carlo Simulation
Mixtures of ultra low amounts of species can be separated in a tube, evacuated well below a microbar, along which the temperature gradually decreases from the closed hot end, by placing the sample into this hot end (zero coordinate). Then the Knudsen flow results in that the components with dissimilar adsorbability on the tube surface make deposits, which peak in different temperature intervals away from zero. It happens despite the absence of any convective flow, which is the basis of all true “chromatographies”. A few experimental works published to date demonstrate separations of both very volatile and quite nonvolatile species.
This “vacuum thermochromatography” (VCT) is based on erratic independent displacements of the molecules up and down the tube. Indeed, a molecule experiences free flights between two sequential collisions with the tube wall, while each strike results in an adsorption event and so in an adsorption sojourn time. Thus the molecule does not keep memory about its incoming velocity vector; it is commonly supposed that the angular distribution of the rebounds follows the cosine law.
The paper presents the first rigorous consideration of the microscopic picture of VCT to substantiate MC simulations. Formulae for the flight length and its projection on the tube axis were derived. Algorithms of calculating random values and the probability density functions for the above quantities were obtained. Erroneous formulae and values met in literature were corrected.
In an isothermal tube, the picture obtained by MC simulations was indistinguishable from the solution of the corresponding diffusion problem. It is the half-Gaussian – because the migration is reflected at zero – and the mixture components differ only in the width of that distribution. However, in the case of VTC, the average adsorption sojourn time, which is proportional to the Boltzmann factor (depending exponentially on the desorption energy), rapidly increases with lower temperature. As a result, two molecules displaced from the given coordinate in opposite directions have different probability per unit time to make next steps. This is the background for evolution of the adsorption peak, which “moves” towards lower temperature with longer duration of the experiment.
Empirical regularities in the peak coordinate and temperature of the simulated peaks as a function of some experimental conditions were obtained. Some reasonable function for fitting the peak profiles was proposed. Attempts to use the diffusion ansatz for the interpretation of VCT data were undertaken though the strong temperature change of the effective diffusion coefficient with the coordinate brings problems in diffusional description.
VCT as a method of preparative separation offers prospects of solving some specific task in radiochemical analyses. One of the goals is finding the energy of desorption of various species . The here obtained equations with semi-empirical parameters allow thermodynamic interpretation of the experimental data. The earlier attempts on these lines are critically discussed.
As to the studies of su
(Flerov Laboratory of Nuclear Reactions, Joint Institute of Nuclear Research,)
Gas phase chemical studies of superheavy elements using the Dubna Gas-Filled Recoil Separator – stopping range determination15m
The use of the Dubna Gas-Filled Recoil Separator (DGFRS)  as a preseparation device for gas phase chemistry experiments with elements 112 and 114 led us to the task of reevaluating the stopping force (STF) of superheavy elements (SHE). In the experiment the DGFRS and the IVO-system  were separated by a thin Mylar window of variable thickness so that the evaporation residues (EVR) can pass it. The reaction product collection chamber (RPC-chamber), filled with gaseous argon and mounted behind the Mylar foil, had to be as small as possible to increase the transport efficiency to the thermochromatography detector COLD. Due to scarce availability, we measured STF data for Hg, Rn, and No in Mylar and gaseous argon at energies of around 30 to 50 MeV. These data were used for an extrapolation tothe STF of the SHE 114.
Stopping force measurements
A 265 MeV Ca-48 beam was delivered from the U-400 cyclotron at the Joint Institute of Nuclear Research (JINR) in Dubna, Russia. The beam was passed through a 1.6 μm Ti window, a 1.6 μm Ti target backing into the target materials. Three different target materials were irradiated: neodymium oxide (nat. Nd2O3, 0.30 mg/cm2), dysprosium oxide (nat. Dy2O3, 0.33 mg/cm2) and lead (208Pb, 0.42 mg/cm2, 1 μm Cu degrader in front). The mainly produced EVR’s in the fusion of Ca-48 with target nuclei are according to HIVAPSI  Hg-185, Rn-206 or No-254, respectively. The EVR’s were separated in the DGFRS according to their mass to charge ratio and guided on an exchangeable Mylar foil of 2, 3 or 5 μm thickness separating the RPC-chamber from the DGFRS. The RPC-chamber had a depth of 18 mm and was filled with thermalizing argon gas of a pressure between 0.0 and 0.4 bar. In the center of the focal plane of the separator at the back wall of the RPC-chamber a 20 x 20 mm silicon detector (PIN-diode) was mounted to detect the signals and the alpha decays of implanted products. Different data points were gained by varying the Mylar foil thickness and the argon gas pressure.
Extrapolation to element 114
For the extrapolation of the stopping range to 114 we used the assumption of proportionality of the STF of a heavy ion to the velocity dependent effective charge (qeff) and the equivalent STF of a proton (epSTF) . These epSTF’s which are uncorrected for any other STF terms, were plotted against 1/ln(Z) an empirically established dependence of the STF on Z of the heavy ion. The obtained values were compared with the stopping code SRIM 2008  and finally used to setup the gas chromatography experiment with elements 112 and 114. The results are accepted for publication .
 K. Subotic et al., Nucl. Instr. Methods A, 2002, 481, 65.
 Ch.E. Düllmann et al., Nucl. Instr. and Meth. A, 2002, 479, 631.
 R. Dressler, PSI Scientific Report 1998, Volume I, 1999, 131.
 J. F. Ziegler, J. P. Biersack, and U. Littmark, „The stopping and range of ions in solids“, Pergamon Press, Kronberg-Taunus, Federal Republic of Germany, 1985
 J.F. Ziegler, et al., SRIM-2008, www.srim.org, 2008.
 D. Wittwer et al., Nuclear Instruments and Methods B (2009).
(University of Bern / Paul Scherrer Institut)
Neutron and photon activation and ion beam techniques in geochemical characterization of moldavites and other impact glasses20m
The study presents results of geochemical characterization of a large collection of tektites and other impact glasses. Impact glasses are produced through large meteoritic impacts by melting of surface materials. Tektites are impact glasses ejected from the impact site to distant strewn fields. The collection included namely moldavites from the major parts of the Central European tektite strewn field, and irghizites - impact glasses from the Zhamanshin crater in Kazakhstan. Several samples of Australasian tektites and Libyan Desert glass were available as well. The characterization has been based on determination of about fifty elements using various modes of instrumental neutron activation analysis, supplemented by instrumental photon activation analysis, prompt gamma activation analysis, PIGE and PIXE. Geochemical data are presented and discussed in view of parent materials and processes involved in formation of various tektites and impact glasses.
(Nuclear Physics Institute, Academy of Sciences of the Czech Republic)
Determination of silicon in beer and beer processing materials by fast neutron activation analysis. Is beer a possible protective factor in preventing Alzheimer´s disease?20m
Silicon is an essential element for organisms. Although the biochemical mechanisms remain obscure, dietary Si is considered important for growth and development of bone and connective tissues. Recently, it has been suggested that Si and silicic acid may decrease the bioavailability of aluminium by blocking its uptake through the gastrointestinal tract and by impeding reabsorption in kidney . Aluminium, a neurotoxin, has lately been implicated as one of the possible casual factors contributing to Alzheimer´s disease, since the element is conducive to oxidative stress in the brain, and oxidative damage is the primary risk factor for Alzheimer´s disease and other neurodegenerative disorders. While many foods contain Si in polymeric form or as hydrated silica – opal (phytoliths), bioavailable Si in beer is present in a monomeric form as a soluble orthosilicic acid H4SiO4 [2,3]. It is the Si form, which may decrease the bioavailability of Al, and consequently may afford protection against Al toxicity in brain. For this reason, we studied the Si content in various Czech beers and beer base materials using fast instrumental neutron activation analysis. Lyophilized samples of several Czech beers and beer processing materials from one brewery (barley, sweet and hopped wort, extracted grain, yeast, hop extract and granulate, nonfiltered and filtered beer) were combusted in a nickel crucible at 600°C in air. Water used for hot mashing of barley was preconcentrated by evaporation. Irradiation behind a Cd shield was used for determination of Si via the short-lived radionuclide 29Al resulting from the 29Si(n,p)29Al reaction with fast neutrons in the ash from the above samples, and/or in the water aliquots. Gamma-ray spectra of the irradiated samples and standards were measured by a coaxial HPGe detector coupled to a Canberra Genie 2000 system. For quality control, reference material NIST SRM 2704 Bufallo River Sediment was assayed. The study has shown how Si comes into beer from the individual input materials. In addition to a Si contained in water, barley and hop are the main sources of Si in beer. It is mainly the hot mashing technique, which extracts orthosilic acid from barley’s and hop’s phytolitic silica. The Si concentration in the Czech beers analyzed were in the range of 14 to 44 mg/L, while water used for hot mashing of barley in the studied brewery contained 7 mg/L of Si. Dietary Si intake in the USA is about 20-50 mg per person per day , while the British diet has been reported to contain 9-23 mg of Si per person per day, with 60 % derived from cereals with poor bioavailability . Thus it is obvious that moderate beer consumption significantly increases intake of bioavailable Si. Therefore, if the rather controversial hypothesis about aluminium´s neurotoxicity holds, beer drinking should be considered a protective factor in preventing Alzheimer´s disease and other Al induced neurodegenerative disorders.
1. M.J. Gonzáles-Muňoz, A. Peňa, I. Meseguer. Food Chem. Toxicol., 46 (2008) 49-56.
2. S. Sripanyakorn, R. Jugdaohsingh, H. Elliot et al.: British J. Nutr., 91 (2004) 403-9.
3. M.J. Gonzáles-Muňoz, I. Meseguer, M.I. Sanchez-Reus et al.: Food Chem. Toxicol., 46 (2008) 1111-18.
4. J.P. Bella, J.D. Birchall, N.B. Roberts: Lancet 343 (1994) 235.
(Nuclear Physics Institute ASCR, Řež, Czech Republic)
Prompt γ activation analysis as performed in Budapest20m
Institute of Isotopes has been a major center in further development of Prompt Gamma Activation Analysis (PGAA). The paper describes the analytical procedure followed at Budapest. The analysis is based on the careful calibration of the detector system. The counting efficiency and non-linearity of the Compton-suppressed high-purity germanium detector is determined regularly, and enables the accurate determination of activities and peak positions. Partial gamma-ray production cross-sections have been determined for the most important prompt-gamma lines of every naturally occurring chemical element using stoichiometric compounds and homogeneous mixtures. A method for qualitative and quantitative analysis has also been developed at our laboratory for the determination of the chemical composition of samples from the peak areas obtained from the prompt-gamma spectra using the spectroscopic data library. The data library and the method have been used for the analysis of a large variety of samples at Budapest and at other PGAA laboratories.
(Institute of Isotopes)
Upgrade of the prompt-γ activation analysis (PGAA) and neutron induced prompt-γ spectroscopy (NIPS) facilities of the Budapest research reactor20m
The Prompt-Gamma Activation Analysis (PGAA) and the Neutron Induced Prompt-gamma Spectroscopy (NIPS) facilities are located at the end of the guided beamline No.1. of the Budapest Research Reactor. In the last few years they were significantly upgraded. The partial replacement and realignment of the neutron guide elements resulted in a factor of four gain of the neutron flux. To make possible the unattended and independent operation of the two stations, a neutron flux monitor and computer-controlled beam shutters have been put into operation. This latter can be programmed to open and close the neutron beam according to a predefined time sequence, thus it will be an ideal tool to perform in-beam activation experiments.
In order to make the PGAA facility even more productive, an automatic sample changer has been designed and manufactured. This can accommodate 16 samples, either solids, powders in sealed Teflon bags, or liquids in vials. A computer program has been developed to control such batch runs.
At the NIPS station, however, more attention is paid to the non-destructive analysis of bulky samples. Therefore a new, bigger and partially dismountable sample chamber is under construction. Moreover, the detection conditions are substantially improved by the installation of a new BGO Compton suppressor and massive lead shielding. Space is reserved for a moving table and for a neutron tomograph, to re-establish the combined Prompt-Gamma Activation Imaging (PGAI) and Neutron Tomography (NT) equipment.
The upgraded facilities offer new possibilities for the routine element analysis and also for the cutting-edge research challenges, and continue to serve international collaborations within the EU FP7 and many other projects.
(Institute of Isotopes, Hungarian Academy of Sciences)
Kinetics of reduction of hexavalent neptunium by nitrous acid in solutions of nitric acid15m
Extraction of hexavalent and tetravalent actinides with tributylphospate (TBP) from their solutions in nitric acid is the most industrially mature process for reprocessing of spent nuclear fuel and is the basis for the development of advanced reprocessing schemes like UREX and TRUEX. One of the less resolved issues is the management of neptunium in the extraction system, because of not clearly defined redox speciation. Neptunium is present in both pentavalent and hexavalent oxidation state that differ greatly in their extractability to the organic phase (hexavalent state being very well extracted by TBP, whereas pentavalent neptunium is almost not extracted). As a result, neptunium is distributed in both organic and aqueous streams of the separation process. Apparently, the most important factor determining the redox speciation of neptunium is the presence of nitrous acid that is formed during the dissolution of spent fuel and also by radiolysis. Nitrous acid HNO2 is relatively well extracted by TBP (log D ≈ 1) and is therefore distributed from the source raffinate solution in further stages of the separation system . If present in small quantities, it autocatalyzes the oxidation of Np(V) by nitric acid, whereas large concentration of HNO2 leads to reduction of Np(VI) back to the pentavalent state – the kinetics of this reaction have been covered in detail by many authors . The kinetics of reduction of Np(VI) by HNO2 have so far attracted only little interest and are the subject of this study.
UV-VIS-NIR absorption spectrophotometry (OceanOpticsTM) in a stirred cuvette was employed in order to study the reaction:
2Np(VI) + HNO2 + H2O ↔ 2Np(V) + NO3- + 3H+
The reaction progress was recorded by following the absorbance at characteristic peak of Np(V) at 981nm and simultaneous observation of the broad absorption peak of HNO2 between 350-400 nm. The reaction orders with respect to concentrations of Np(VI) and HNO2 were found to be close to one. Increasing the concentration of nitric acid at constant ionic strength (µ=4M H/LiNO3) had a decreasing effect on the reaction rate with an order of -0.8. The dependence of the rate constant on the ionic strength and temperature will be also reported.
(Oregon State University)
The complexation of Tc(IV) with organic ligands in radioactive waste15m
The preferred option in the UK for the management of higher-activity radioactive wastes is to store it in a deep Geological Disposal Facility (GDF). This may then be backfilled with a cementitious material. Once closed, the GDF will become saturated with groundwater and highly alkaline porewater will develop with an initial pH of ca. 13.4. This will decrease to 12.5 as groundwater flow removes the NaOH and KOH present. Mineral phases in the cement will then act as a buffer and maintain the pH at 12.5 for ca. 105 years. Corrosion of waste-containing steel canisters will lead to the gradual formation of reducing conditions. Thus, the behaviour of radionuclides in the waste must be understood in the context of this chemistry.
Organic complexing agents will be present as inherent components of the waste, especially isosaccharinic acid (ISA) and other polyhydroxylated carboxylic acids which will be formed by the degradation of cellulose. These are highly complexing and can cause significant increases in radionuclide solubility at high pH. The GDF will not be homogenous, there are likely to be areas of reducing and oxidising potential. This heterogeneity could mean that both Tc(VII) and Tc(IV) are present within the GDF. If TcO4- migrates into an area in which reducing conditions exist, the organics may complex with technetium during reduction to form water-soluble complexes. Also of relevance is the possibility of increased solubility when organics are in contact with reduced technetium (TcO2(am)). In other words, do organics affect the reduction of Tc(VII) to Tc(IV)? Therefore, studies have been undertaken in which TcO4- was reduced electrochemically, and by Sn(II) and Fe(II), in the presence and absence of ISA, gluconic acid, EDTA, NTA and picolinic acid, to determine whether they caused an increase in Tc solubility when TcO2(am) was contacted with them.
In the presence of ISA and gluconic acid a lowering of [Tc(aq)] took place on reduction, showing such ligands did not prevent some reduction occurring. If this reduction was to Tc(IV), then the final aqueous concentration should be the same as that produced by the addition of the same ligands to Tc(IV) solution at steady state, i.e. the Tc(IV) complexes would again be formed, but by 2 different routes. However, the final [Tc](aq) in the system where reduction took place in the presence of ISA and gluconate was higher than when starting from TcO2(am). This indicates that Tc(VII) may not have been reduced to Tc(IV) but an intermediate oxidation state complex such as Tc(V) may have formed. This concept is well known in 99mTc radiopharmaceuticals, where polyhydric complexes of Tc(V) can be formed by the reduction of pertechnetate in aqueous solution of excess O-donor ligand, although in pharmaceuticals this is not carried out at high pH.
Cobalt bis(dicarbollide) ions with covalently bonded TODGA-like substituents for actinide and lanthanide extractions15m
The partitioning and transmutation of long-lived nuclides such as minor actinides from high liquid waste (HLW) issued from nuclear fuel reprocessing is a method how to reduce the long-term environmental burder of HLW. In recent years, several HLW partitioning processes using different extractant agents have been developed. Among them, the tridentate ligands like N,N,N′,N′-tetraoctyl diglycolamide (TODGA) are one of the most promising extractants for the recovery of actinides and lanthanides in the nuclear fuel treatment.
In this work, the recently developed extractants based on cobalt bis(dicarbollide) ion(1-), [(1,2-C2B9H11)2-3-Co)]- (COSAN) functionalized with TODGA like substituents were evaluated for extraction of trivalent actinides and lanthanides from acidic waste solutions. The extractants under study differed in substitution of the amide nitrogen (e.g. by butyl-, octyl-, terc-octyl-, dodecyl-, benzyl- groups) and the mode of attachment of two cobalt bis(dicarbollide) anions (with or without spacer) to diglycolyl acid platform by amidic bonds. It was found, the compounds with longer diethyleneglycol connectors between COSAN cage and diglycolamide group extracted trivalent lanthanides and actinides very effectively even from highly acidic nitric acid solutions. Additionally, the extraction efficiency of such derivates was significantly higher than that of comparable organic TODGA molecules without COSANs. The most perspective compound from this series corresponds to the formula X-[(8-CH2-CH2O)2-1,2-C2B9H10)(1’,2’-C2B9H11)-3,3’-Co]2, where central amidic unit X corresponds to [(n-C8H17-NCOCH2)2O]. We will be demonstrate here, this extractant enables good extraction of trivalent lanthanides and actinides from majority of fission products presented in the simulated PUREX feed. Trivalent radionuclides can be effectively stripped using complexants. This extractant will be further studied for possible technological applications.
We thank for partial support from Grant Agency of the Czech Republic (Project No. 104/09/0668), Radioactive Waste Repository Authority (Project 2007/006/Šumb and 2009/002/Šu), and Research Plan AV0Z40320502 from AS CR.
(Nuclear Research Institute plc Řež)
Extraction of radionuclides with solutions of complexing agents in supercritical fluids and compressed gases15m
One of the main advantages of extraction with supercritical fluids (SCF) or liquid gases (LG) is a possibility of the reagent-free regeneration of "solvent", which sharply decreases the secondary waste volume. As a result, in last 20 years the researcher in many countries focus their attention on the supercritical fluid extraction (SFE) of the trace amounts of radioactive and heavy metals for treatment to remove and decontamination of various solid objects (including soils) and on SFE of actinide macroamounts for reprocessing of the spent nuclear fuel of the nuclear power plants (SNF NPP).
In this work we analyze the similarities and differences between the liquid-liquid extraction of radionuclides and extraction with SCF and LG and the prospects of extraction using supercritical and liquid gases in radiochemistry..
In last 20 years the data on SFE of a series of metals were published in more than 100 papers. The detailed data was presented on SFE of U, Th, rare-earth elements (REE), Co, Cu, Mn, Pu, Np, and Am. The SFE of U, Th, and REE РЗЭ with tri-n-butyl phosphate (TBP) and its mixture with diketones were also extensively studied. Rather detailed data were presented on SFE of transuranium elements and fission products using carbon dioxide solutions of TBP, diketones and their mixtures and even on recovery of these elements from non-irradiated nuclear fuel and from SNF NPP. SFE of Cs and Sr with solutions of organic acids and polyethers was also well studied.
The detailed data are published of the extraction of U, REE, Cu, Pb, Zn, Cd, Cr, and As using carbon dioxide solutions of various acids such as di-2-ethylhexyl phosphoric, bis(2,4,4-trimethylphenyl) phosphoric (cyanex-272), bis(2,4,4-trimethylphenyl)monothio phosphoric (cyanex-302), bis(2,4,4-trimethylphenyl)dithio phosphoric (cyanex-301), and di-2-ethylhexylthio phosphoric acids.
Our analysis showed only slight differences between the extraction of macro- and microamounts of metal cations with solutions of complexing agents in liquid and supercritical СО2 and liquid-liquid extraction. At the same time it should be noted that:
low viscosity and high diffusion rate allows performance of extraction in СО2 without mixing of the phases;
СО2 can affect pH of the liquid phase being in equilibrium with it;
main difference between the extraction of metal cations with solutions in liquid and supercritical СО2 and liquid-liquid extraction are observed for microamounts of metals.
Moreover, it should be mentioned that the technologies of SNF reprocessing and procedures of deactivation in supercritical and compressed СО2 and Freons are the most promising for radiochemistry The advantages of these processes are sharp decrease in the volume of secondary liquid radioactive wastes; absence of organic solvents and toxic compounds, and rather small operation temperature (25-80оС). It should be noted that the use of Freons instead of СО2 allows to decrease the working pressure to 1-4 MPa.
(Khlopin Radium Institute RPA)
Electrochemical separation of actinides from molten LiCl-KCl on solid Al cathodes15m
An electrorefining process in molten chloride salts using solid aluminium cathodes is being developed in the Institute for Transuranium Elements to recover all actinides from metallic spent nuclear fuel. In this process, actinides are group-selectively electrodeposited on the cathode in a form of solid actinide-aluminium alloys. Fission products are anodically co-oxidised from the fuel together with actinides to the electrolyte. Without purification of this carrier salt, the process would have to be stopped after concentration of the dissolved fission products would become too high to prevent selective deposition of actinides on the cathode. A multiple-steps procedure is considered for cleaning of the salt and a process refered as 'exhaustive electrolysis' is proposed for the first purification step. Similarly to the electrorefining process, this technique is based on the group-selective electrodeposition of actinides on solid aluminium cathodes forming actinide-aluminium alloys. On the anodic side, chlorine gas is produced by electrochemical decomposition of the carrier salt. The presented work was carried out in order to prove feasibility of the method. Two galvanostatic electrolyses were realised and the potentials of both electrodes were constantly followed. Uranium was successfully recovered from LiCl-KCl melts containing UCl3 and a mixture of UCl3-NdCl3 and its concentration decreased from 1.7 to 0.1 wt. % with no co-deposition of neodymium. Although the maximum applicable current densities were relatively low, the results are promising, showing high current efficiency and selectivity of the proposed method. A design and application of a special chlorine gas producing inert anode is also discussed.
(European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU))
The effect of competition from other metals on nickel complexation by α-isosaccharinic, gluconic and picolinic acids15m
The UK has an underground repository concept with a combination of engineered and natural barriers. Cementitious materials will produce high pH conditions for at least 1 Ma and surfaces for sorption which will greatly reduce the solubility of many radionuclides. Likely to be in the repository are many organic ligands, as inherent components of wastes or due to the degradation of organics, e.g. cellulose. It has been shown that cellulose degradation products, e.g. α-isosaccharinic acid (ISA), can substantially increase the solubility of radionuclides. Picolinates are in some waste-streams due to the use of picolinic acid in decontamination. Gluconic acid is structurally similar to ISA, a strong ligand useful for comparison purposes and may occur in a repository as a cement additive. From pH 11.5 to 13.5, Ni is fairly insoluble. The 3 ligands increase its solubility by forming aqueous complexes - a process that is fairly well understood. The purpose was to investigate the effects on Ni complexation, of competition from other metals. A repository will also contain Fe metal so experiments were performed in its presence and absence. Predictions of Ni solubility were made for each system to aid the interpretation of competitive effects.
Measured [Ni] in the absence of other metals showed good correlation with calculated values. There was evidence for slight sorption of Ni to Th and Eu phases formed. There was no significant effect due to other metals and/or solid phases being present. In general, the calculated [Ni] trend was followed with picolinate. Th and Hf had little effect on Ni solubility in the presence of picolinate, Co reduced [Ni], which might be expected as it complexes in a similar fashion, above pH 13 all metals caused a significant reduction in [Ni]. This may have been due to sorption to solid phases, or coprecipitation, with Ni being scavenged out as the lowest inventory metal.
All the Ni was complexed by gluconate. Eu had no significant effect at the highest Ni concentration. Hf, Co and Th reduced [Ni] across the pH range, probably due to complexation with gluconate. Eu had a marginally greater effect at a [Ni] = 10-3 M, suggesting a very slight amount of complexation. Hf again had little effect. The Th results were the most difficult to explain. At [Ni] = 0.01 and 0.0001 M, Th affected [Ni] as though forming strong gluconate complexes, but not at 0.001 M. At the lowest [Ni], all competing metals significantly reduced [Ni]. Th had complexed strongly with gluconate, causing Ni to precipitate. Hf had a similar effect to. Co significantly reduced [Ni] in line with its predicted effect. Eu had a significant effect on [Ni] reducing it from the predicted 10-4 M to ca. 2 x 10-6 M.
Fe was predicted to have no effect on [Ni] by complexation with ISA. The measured [Ni] was lower than the calculated in virtually all cases, including those with no competing metal. This may have been caused by sorption to Fe(s). No significant competition effects from other metals were observed.
A comparitive study of U(III) and U(IV) complexes in a room temperature ionic liquid system15m
Room temperature ionic liquids (RTILs) were known as early as the 19th century beginning with alkylammonium nitrates. The field grew in the 1970s by using combinations of air and water sensitive aluminum halides with an organic cation salt. While these ionic liquids were useful and had many desirable features, they were extremely sensitive to air and water, limiting their utility. RTILs today are salts that are liquids from as low as -96 °C to up to 100 °C. RTILs are of high interest in many fields of study because of their negligible vapor pressure, high electrochemical stability, high conductivity, and wide electrochemical windows. In addition, RTILs are useful systems for studying f-elements in the absence of hydrolysis.
Included in this work are studies of multiple uranium complexes in a room temperature ionic liquid system, [Me3NnBu][N(CF3SO2)2]. Uranium materials in the 3+ and in the 4+ oxidation states were prepared in inert atmosphere conditions. Infrared and ultraviolet-visible spectroscopy was utilized to give details regarding the speciation of each system. Electrochemical analysis was executed, including cyclic and square wave voltammetry as well as electrodeposition from both oxidation states. The resulting electrodes were then analyzed using scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction to evaluate the nature of the uranium deposit on the electrode surface. A comparison of the resulting oxidation and reduction processes observed during electrochemical analysis as well as the electrodeposits will be made.
(University of Nevada, Las Vegas)
A study of heterogeneous equilibria in the saturated aqueous solutions of uranoarsenates and uranophosphates of alkaline and alkaline-earth elements20m
Uranoarsenates and uranophosphates belong to a numerous difficult soluble compounds that can be formed by the ingress of various uranium-containing waste in the environment and can also be used as uranium-fixing matrices in technological processes. Research of the state of these compounds in aqueous solutions, of their hydrolytic stability and solubility, and of transformations of uranoarsenates and uranophosphates into other chemical compounds both in the solid phase and in a solution is important. In this work detailed research of the state of Mk(BvUO6)k.nH2O compounds (Bv–As,P; Mk–H+,Li+,Na+,K+,Rb+,Cs+,NH4+,Mg2+,Ca2+, Sr2+,Ba2+) in aqueous solutions at 25°C within a wide range of acidity is presented.
It has been found that behavior of all Mk(BvUO6)k.nH2O compounds in aqueous solutions obeys the general laws due to their structural and functional similarity. Acidity has the most essential effect on the chemical stability of uranium compounds under study. Composition and structure of the solid phase, ionic-molecular forms, and concentrations of U(VI), As(V), P(V) and Mk in equilibrium solutions depend on pH. In acidic medium (рН<2) difficult soluble acid with composition of HBvUO6∙4H2O is formed as a result of ionic exchange in the solid phase. In the case of the Mk(BvUO6)k∙nH2O interaction with aqueous solutions of the alkaline elements hydroxides (рН>10) As(V) and P(V) are leached into the solution and insoluble uranates are formed. In the intermediate interval (2<рН<10) secondary solid phases are formed in quantities defined by acidity of the equilibrium solutions. (UO2)3(AsO4)2∙12H2O, (UO2)3(PO4)2∙8H2O and UO3.2H2O as synthetic analogues of the natural minerals should be mentioned among these phases. The solubility of all compounds with formulae Mk(BvUO6)k.nH2O has minimal value in neutral solutions (10-6-10-5М) and sharply increases with addition of acid or base. The uranophosphates are characterized by higher chemical stability than uranoarsenates. The finer distinctions in behavior of Mk(AsUO6)k.nH2O and Mk(PUO6)k.nH2O are caused by the nature of the Mk elements, and they reveal themselves in conversions of the secondary phase formation reactions and in the acidity-base intervals of the primary solid phase existence.
A physicochemical model characterizing quantitatively the equilibrium state in the heterogeneous systems under study is proposed for predicting the processes occuring when inorganic uranium compounds dissolve. Using the model it is possible to calculate the state diagrams of the solid phases and the equilibrium solutions over the phases. In addition, it is possible to evaluate various heterogeneous equilibria constants.
(Nizhny Novgorod State University named after N.I. Lobachevsky)
Americium alloys with gold and copper20m
Over many years JSC “SSC RIAR” has been performing activities on the production and investigation of metals of transplutonium elements (TPE), their alloys and compounds.
This paper presents the results of production and X-ray examination of micro-samples of americium-241 compounds with gold and copper, i.e. identification of crystal structures of the compounds obtained and calculation of crystal lattice parameters, study of the effect of alpha-decay on the intermetallide crystal structures.
Samples of Am-Au and Am-Cu systems were prepared by high temperature condensation of metal americium vapor onto appropriate substrates. The X-ray examination results of the compounds produced are shown in the table below.
Table. Crystal lattice parameters of phases detected during investigation of Am-Au and Am-Cu systems
System Phase Syngony
(space group) Lattice parameters
a, Å b, Å c, Å V, Å3
Am-Au Au6Am Tetragonal (P42/ncm) 10.3894(7) - 9.7036(7) 1047.4(2)
AuAm Orthorhombic (Pnma) 7.402(2) 4.564(1) 5.826(1) 196.8(1)
AuAm Cubic (Fm3m) 4.784(2) - - -
Am-Cu Cu5Am Hexagonal (P6/mmm) 4.958(1) - 4.175(2) 88.88(5)
Note. V – is volume of a crystal lattice elementary cell. Definition errors of the last character are given in brackets after the lattice parameter values.
The investigated systems did not show mutual solubility of their components at room temperature.
In the Am-Au system three intermetallic compounds were found: Au6Am (of Au6Sm structural type), AuAm (of CuCe structural type) and intermetallide AuAm (of CsCl structural type).
In the Am-Cu system intermetallide Cu5Am (Cu7Am) (of Cu5Ca structural type) was detected. The effect of alpha-activity of nuclide 241Am on crystal structure of the obtained intermetallide (Fig.) was investigated.
Fig. Change in the elementary cell volume of intermetallide Cu5Am as a function of self-irradiation time.
(JSC "State Scientific Center - Research Institute of Atomic Reactors")
Application of coprecipitation for the study of chemistry of Rf20m
Chemical identification of radionuclides in the decay chains of the recently discovered transactinide elements may serve as a method for confirming the discovery . The longer half-lives of radionuclides of transactinides discovered in the An + 48Ca reactions expands the application of radiochemical techniques for their chemical characterization . The method of cocrystallization can give valuable information on properties of transactinide compounds, not available in the macroscopic, therefore the identification of coprecipitation mechanism of lighter homologues of transactinides is of scientific interest.
Here we report the coprecipitation behavior of Ti, Zr, Hf and Th as lighter homologues of Rf with lanthanum fluoride. The kinetics of coprecipitation and distribution of group 4 elements between the liquid and solid phase, both preformed and formed during the distribution process, was studied as a function of concentration of the micro- and macrocomponent, foreign multivalent ions, HF, pH in solution. The solid phase of prepared samples was characterized by electron microscopy (SEM and TEM). The results show that the coprecipitation mechanism of Zr and Hf with LaF3 is different from Ti and Th and can be assigned to heterovalent isomorphism. A possibility of using coprecipitation with lanthanum fluoride for comparative investigation of the behavior of Rf in HF solutions was demonstrated.
This work was supported by the RFBR (grant No. 09-03-12029-ofi_m).
1. S. N. Dmitriev et al., Mendeleev Communications. 15, 1, 1-4 (2005).
2. Yu. Oganessian, J. Phys. G.: Nucl. Part. Phys. 34, R165-R242 (2007).
(Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research)
Electrochemical and spectroscopical investigation of uranium in room-temperature ionic liquids20m
Room-temperature ionic liquids (RTILs) consist of organic cations and organic or inorganic anions. Beside their fluidity over a large temperature range, they have versatile physical and chemical properties, e.g. low vapour pressure, thermical and chemical stability . In our investigation, the wide electrochemical window of RTILs is of particular importance. RTILs are considered as “green solvents” and may open up new options in industrial actinide separation .
This work is about the redox behaviour of hexavalent uranium in 1-butyl-3-methylimidazolium based RTILs. Two different methods have been used: cyclic voltammetry to achieve information about the redox behaviour of uranium(VI) and electrochemical deposition to get samples for X-ray photoelectron spectroscopy (XPS). In both cases the same uranium RTIL solutions have been used. Uranium oxalate (UO2C2O4) has been dissolved in
1-butyl-3-methylimidazolium methylsufate (BmimMsu) and 1-butyl-3-methylimidazolium thiocyanate (BmimSCN) under argon atmosphere. Afterwards the solutions
(c(U) ~ 8•10-3 mol/L) have been dried under reduced pressure and heating to minimize the water content in these stock solutions. The amount of water has been determined via
Karl-Fischer titration (≤ 10 ppm).
For the cyclic voltammetric measurements glassy carbon has been used as working electrode, titanium as counter electrode and platinum as quasi-reference electrode (versus ferrocene/ferrocenium). All experiments have been carried out under argon atmosphere. BmimMsu and BmimSCN provide an electrochemical window of 4.5 – 5.0 V, therefore the reduction of U(VI) to U(IV) should be possible. Actually for both UO2C2O4 RTIL solutions cyclic voltammograms have been achieved, which showed a similar progression with a shift of the redox potentials. The cyclic voltammograms suggest a quasi-reversible reduction of uranium(VI) to uranium(IV). The potentials for the U(VI)/U(IV) reduction in BmimMsu and BmimSCN were -1.9 mV and -2.0 mV (vs. SHE), respectively.
To verify the reduction of U(VI) to U(IV), samples have been prepared under argon atmosphere for XPS measurements. The uranium was deposited on a titanium foil applying a potential of 2 V for 3 h. The measured binding energies for the U 4f and U 5f XPS-lines confirm the reduction of hexavalent uranium to the tetravalent oxidation state.
By combining two different methods, it was possible to demonstrate that U(VI) can be reduced to U(IV) and deposited as tetravalent uranium on titanium foils using RTILs as solvent.
 K. Binnemans, Lanthanides and actinides in ionic liquids, Chem. Rev. 2007, 107, 2592-2614
 A.E. Visser, R.D. Rogers, Room-temperature ionic liquids: new solvents for f-element separations and associated solution chemistry, J. Solid State Chem. 2003, 171, 109-113
(Institute of Nuclear Chemistry, Johannes-Gutenberg-Universität Mainz)
Electrochemical behaviour of curium in chloride melts20m
Curium isotopes contained in spent nuclear fuel have a high specific heat rate and long half-life, and they should be recovered from high-level wastes (HLW) and transmutated. Molten chlorides have more high radiation resistance than aqueous and organic media. This fact is of significant importance because curium has a high specific activity. There is not much information about the behaviour of curium in molten chlorides. Data available are referred to the conventional standard potential of curium in the alloy formed with zinc  and distribution coefficient between salts and liquid metal phase . Data on thermodynamics of formation for oxygen-containing curium compounds in chloride melts was obtained by authors  with using of potentiometric titration. This work is devoted to study of non-oxygen curium compound formation in chloride melts.
The following standard electrochemical methods were used: CV, SWV, DPV, chrono potentiometry and dynamic galvanometry.
Dependences of formal standard electrode potential of curium, Gibbs energy change and other parameters on temperature and effective radius of solvent cation were obtained. Also Pourbe diagrams were drawn.
Study was carried out in frame of ISTC Project # 3261. The authors express their appreciation to CEIMAT (Spain), ITU (Germany), CEA (France) and AlbaNova University Centre Royal Institute of Technology Nuclear and Reactor Physics (Sweden) for support and interest to this work.
1. V.P.Kolesnikov, V.N. Kazantsev, O.V.Skiba Electrochemical behavior of americium and curium in molten alkali metal chlorides. Radiochemistry, 1977, 19, No.4, pp. 545–548
2. T.Koyama., et al.:J.Alloys Compounds, 189,37 (1992).
3. A.G. Osipenko, A.A. Mayorshin, A.V. Bychkov Study of Reaction of Curium Oxy-Compound Formation in Molten Chlorides//Radiochimica Acta 97,227-230(2009)
(Research Institute of Atomic Reactors)
Formation of ruthenium alloys with curium and technetium20m
Presented are the results of production and x-ray examination of ruthenium compounds with curium and technetium.
A curium -244 alloy microsample was produced by the high-temperature condensation of curium vapor onto the ruthenium substrate and then analyzed by the x-ray diffractometric method. Two intermetallides were detected in the sample: Ru2Cm with a hexagonal lattice of the Zn2Mg type with parameters a = 5.279(1) Å, c = 8.812(3) Å; Ru3Cm with a cubic lattice of the Cu3Au type and a = 4.151(2) Å. Data were obtained on the x-ray amorphization of lattices of both intermetallides under intensive alpha-decay of curium-244.
The study on the formation of ruthenium alloys with technetium is carried out as part of investigations of technetium transmutation. This process can be implemented in the high-flux reactor SM-3 (Dimitrovgrad, Russia) at an acceptable rate. For the subsequent separation of ruthenium from irradiated samples data are required on the phase relationship in the technetium-ruthenium system under irradiation conditions. This paper describes the x-ray diffractometric examination of samples of starting metal technetium and also those irradiated in the reactor up to a 19, 45 and 70% ruthenium accumulation. The study demonstrates that as a result of the ruthenium accumulation homogeneous solid ruthenium-technetium solutions with a hexagonal close-packed (HCP) structure are formed. Crystal lattice parameters a and c regularly decrease with increasing ruthenium concentration. The existence of a sufficiently strong dependence between the crystal lattice parameters and amount of ruthenium accumulated under irradiation allows the definition of ruthenium content in the irradiated technetium by using the x-ray diffractometric method.
(JSC "State Scientific Center - Research Institute of Atomic Reactors")
Investigations on stability and structure of thorium colloids20m
This work presents results about the formation of thorium(IV) colloids and precipitates in the presence of silicic acid. Three methods were used for the preparation of the thorium compounds:
- Experiment A: Silicic acid concentrations and ionic strengths were adjusted in the presence of preformed stable ThO2 colloids at neutral pH (0.4 mM Th; 0 3 mM Si; I = 0.05 M NaClO4)
- Experiment B: Precipitation of ThO2 colloids in the presence of silicic acid by neutralization from the acidic side of the pH scale (1 mM Th; 0-4.2 mM Si; I = 0.1 M NaClO4)
- Experiment C: Precipitation of Th(IV) colloids in the presence of silicic acid by neutralisation of a Th(IV) carbonate solution from the alkaline side of the pH scale (1 mM Th; 0-3 mM Si; I = 0.1 M NaClO4)
For the characterization of the colloids, zeta potential measurements as well as NMR and extended X-ray absorption fine structure (EXAFS) spectroscopy were applied.
The zeta potentials of the thorium compounds in experiments A, B and C were determined by laser Doppler velocimetry at pH values of 2 – 10. These measurements allowed the estimation of the isoelectric points (IEPs) of the colloids and conclusions about the colloidal stability of the suspensions formed.
By the addition of silicic acid to preformed ThO2 colloids (experiment A), a significant shift of the IEPs from pH ~ 8.5 to lower values (pH ~ 6.5) was observed. Similar results were found in experiment B. Here, the IEP shifted from pH ~ 7.3 to pH ~ 6.0 in the presence of silicic acid. For both experiments the shift of the IEP was a function of the silicic acid concentration. Obviously, the significant amounts of silicate in/on the Th(IV) particles shift the IEP toward the IEP of pure silicic acid (pH < 3).
On the other hand, the results of the zeta potential measurements on the Th(IV) colloids from experiment C demonstrated that the IEP did not change in the presence of varying amounts of silicic acid but remained constantly at pH ~ 5.2. It was also significantly lower than the IEPs of the colloids from experiments A and B formed under acidic conditions. The IEP behaviour of the experiment C colloids is not yet fully understood.
The results of 29Si solid state NMR and EXAFS spectroscopy of the thorium samples from experiment C showed that silicate was built in into the solid structure of ThO2. A possible mechanism is the partial replacement of the Th-O-Th bonds by bridging silicic acid and the formation of Th-O-Si-O-Th links. It is discussed whether the integration of silicic acid in the solid structure results in the formation of a still unknown thorium compound or a thorite (ThSiO4) like material was formed.
 R. K. Iler, K. Ralph, The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica, John Wiley & Sons, 1979.
Kinetics of neptunium(V) conversion in strong nitric acid solutions containing potassium phosphotungstate, K<sub>10</sub>P<sub>2</sub>W<sub>17</sub>O<sub>61</sub>20m
Behavior of Np(V) in strong nitric acid solutions with different strength (1,0 ÷ 3,0) mol∙l-1 and KPW (1 ÷ 5)∙10-3 mol∙l-1, containing potassium phosphotungstate, K10P2W17O61 (KPW) is examined by spectrophotometric method .
It is established that Np (V) final conversion products under studied experimental conditions are Np (IV) and Np (VI), and the process is going in accordance with a first-order rate law in regard to neptunium(V) concentration.
(Russia, Rosatom, JSC"State Scientific Center-Research Institute of Atomic Reactors", Radiochemical Unit)
Novel U(VI) Schiff base complexes: synthesis, structural characterization, and extraction studies20m
The coordination chemistry of uranium in different oxidation states has recently generated much attention due to several reasons. The most important reason is the separation of U(VI) present in radioactive waste, but also the effects of U(VI) on our environment are of great interest. The extraction and separation of U(VI) and other actinides, especially the separation from lanthanides, is most difficult due to their similar chemical behavior. However, the introduction of soft heteroatoms, as imine nitrogen, in the ligand systems could be used as a tool for more selective and effective binding and extraction. We have synthesized and characterized some novel U(VI) complexes using multidentate Schiff base ligands. Structures of these complexes were characterized by X-ray crystallography and DFT calculations. It is the intention of this work to determine not only the structure of these complexes but also the extraction ability of the ligands towards U(VI) and Eu(III).
 a) A.E.V. Gorden et al. (2003) Chem. Rev. 103, 4207-4282; b) J.D. Van Horn, H.
Huang (2006) Coord. Chem. Rev. 250, 765-775; c) A.E.V. Gorden et al. (2008)
Dalton Trans. 2966-2973; d) A.E.V. Gorden et al. (2007) Inorg. Chem. 46, 8309-8315;
e) M. Ephritikhine (2006) Dalton Trans. 2501-2516.
 Nash K. L. (1993) Solvent Extr. Ion Exch. 11, 729-768.
Production and investigation of thin films of metal actinides (Pu, Am, Cm, Bk, Cf)20m
Under limited availability of transplutonium metals special techniques and methods of their production have been developed that combine the process of metal reduction from a chemical compound and preparation of a sample for examination. In this situation the evaporation and condensation of metal onto substrate becomes the only possible technology.
Thin film samples of metal curium (244Cm, 248Cm) and 249Bk were produced by thermal reduction of oxides with thorium at 1700°С. Metal layers of 0.6-180 µm and 2.5 µm thickness, respectively, were deposited onto the tantalum substrate. For production of metal californium 249Cf in the form of a layer with a thickness of (2.4 ± 0.3) µm the method of thermal reduction of oxide with lanthanum was used.
Samples of 238Pu in the form of a film with a layer thickness between 1 and 40 µm and those of 239Pu with a layer thickness between 15 and 40 µm for X-ray structure analysis were prepared by direct high temperature evaporation and condensation of metal onto substrate. For production of 241Am sources a gram sample of plutonium was used containing about 18.5% of americium at the time of production.
Thermal decomposition of Pt5Am intermetallic (262 mg mass) in vacuum was used to produce metal americium with about 80% yield.
Resistivity of metal californium (249Cf ) films with a thickness of (0.8 0.1) and (0.1 0.01) µm was measured using the potentiometric method. Initial resistivity values of samples 1 and 2 (5-6 hours after their production) made up (570 80) and (9100 1200) µOhm•cm, respectively. The resistivity of both film samples was found to decrease exponentially with increasing temperature. Negative temperature coefficient of resistivity achieved –(450 22)•10-6 К-1 in the temperature range 77 – 300 К.
The analysis of literature data on metal californium structure allowed an observation of a tendency to form the preferred DHCP structure with increasing sample mass. And, on the contrary, the smaller is the quantity of metal californium under examination, the higher is the probability of interpretation of X-ray diffraction analysis results based on FCC and HCP structures.
The performed study on the effect of high specific activity on the crystal structure of plutonium isotope (238Pu) thin layers showed an appearance of non-equilibrium (at room temperature) phases. However, many aspects of this observable phenomenon have not been investigated yet experimentally and comprehended theoretically.
(JSC "State Scientific Center - Research Institute of Atomic Reactors")
Radiographic examination of curium alloys with cobalt, iron, and carbon20m
Over many years JSC “SSC RIAR” has been performing activities on the production and in-vestigation of metals of transplutonium elements (TPE), their alloys and compounds.
This paper presents the results of production and radiographic examination of micro-samples of curium-244 compounds with ion, cobalt and carbon, namely an identification of crystal lattices of the compounds obtained and calculation of crystal lattice parameters, study on the effect of inten-sive alpha-decay on crystal structures of intermetallides and carbides.
Samples of the Cm-Co, Cm-Fe and Cm-C systems were prepared by high temperature con-densation of metal curium vapor onto corresponding substrates. In the Cm-C sample such a “sub-strate” represents a thin amorphous carbon layer applied preliminary onto a flat iridium plate. The radiographic examination results of the produced compounds are presented in the table below.
Crystal lattice parameters of phases detected during investigation of the Cm-Fe, Cm-Co and Cm-C systems.
System Phase Lattice Lattice parameters
a, Å c, Å V, Å3
Cm-Co Сo17Cm2 Hexagonal (P63/mcm) 8,378(7) 8,070(5) 491(1)
Co5Cm Hexagonal (P6/mmm) 4,88(1) 4,08(4) 84(1)
Co2Cm Cubic (Fd3m) 7,242(2) - -
Cm-Fe Fe17Cm2 Hexagonal (P63/mmc) 8,406(3) 8,122(2) 497,0(5)
Fe2Cm Cubic (Fd3m) 7,213(2) - -
Cm-C Cm2C3 Cubic ( )
8,3904(5) - -
Cm3C FCC 5,172(2) - -
Note. In the column “Lattice” a lattice spatial group is indicated in brackets. V – is volume of a crystal lattice elementary cell. Definition errors of the last character are given in brackets after the lattice parameter values.
In the Cm-Co system three intermetallic compounds were detected: Co17Cm2 (hexagonal lat-tice of spatial group P63/mcm), Co5Cm (hexagonal lattice of spatial group P6/mmm) and intermetal-lide Co2Cm (cubic lattice of spatial group Fd3m). Cadmium did not show any solubility in - and -Со at room and elevated temperature.
In the Cm-Fe system two intermetallic compounds were detected: Fe17Cm2 (hexagonal lat-tice of spatial group P63/mcm ) and Fe2Cm (cubic lattice of spatial group Fd3m). This system did not show mutual solubility of its components at room temperature. The effect of high alpha-activity of 244Cm nuclide on the crystal structure of intermetallide Fe2Cm was demonstrated.
In the Cm-C system carbides Cm2C3 and Cm3С with a cubic lattice were detected, which were isostructural with regard to carbides Am2C3 and Sm3С. Crystal lattice parameters of the cu-rium carbides were calculated and data on their x-ray amorphization induced by intensive 244Cm decay were obtained.
(JSC "State Scientific Center - Research Institute of Atomic Reactors")
Sorption of Ti, Zr, Hf and Nb, Ta as homologues of Rf and Db from mixed aqueous–organic HF solutions20m
In order to optimize conditions for isolation and study of chemical properties of Rf and Db , we investigated sorption of their lighter homologues Ti, Zr, Hf, Nb and Ta, from HF solutions in water-miscible organic solvents using the Dowex 50x8 cation exchange (CIX) and AG 1x8 anion exchange (AIX) resins. We studied dependence of sorption on concentration of HF and acetone. We found that using the AIX resins the distribution coefficients of Ti, Zr, Hf and Nb increased and those of Ta decreased with increasing content of acetone in HF solutions.
The results indicated that in concentrated (> 3 M) HF solutions containing acetone, group 4 elements formed MF73– (M = Ti, Zr, Hf) complexes whose stability decreased in reverse order of sorption Zr > Hf > Ti. Obtained results are in agreement with previously reported data [2, 3] where using CIX chromatography and HCl-HF mixed solutions group 4 elements were separated and eluted in order of Zr > Hf > Ti > Th.
Under the same conditions, group 5 elements predominately formed complexes NbOF52– and TaF72– with stability considerably different, which decreased in sequence Nb > Ta. We found optimal conditions for separation of the elements using CIX and AIX chromatography. The advantages of studying chemical properties of Rf and Db in aqueous HF solutions mixed with organic solvents are briefly discussed.
This work was supported by the RFBR (grant No. 09-03-12029-ofi_m).
1. S. N. Dmitriev et al., Mendeleev Communications. 15, 1, 1-4 (2005).
2. N.V. Aksenov et al. Radiochemistry 50, 4, 381, (2008).
3. N.V. Aksenov In: Abstracts of the XV International Conference in Fundamental Sciences “Lomonosov-2008”, Moscow State University, April 8-11, Chemistry, 543, (2008).
(Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research)
Structures of hydrated and hydrolyzed thorium(IV) determined by EXAFS and LAXS20m
The hydrated thorium(IV) ion is nine-coordinate in strongly acidic aqueous solution with a mean Th-O bond distance of 2.45(1) Å as determined by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS) . The presence of a second hydration sphere was indicated by LAXS with cca 18 water molecules at 4.66(2) Å. Structural studies in aqueous solution of the hydrolysis products of thorium(IV) identified three different types of hydrolysis species: a μ2O-hydroxo dimer, [Th2(OH)2(H2O)12]6+, a μ2O-hydroxo tetramer, [Th4(OH)8(H2O)16]8+, and a μ3O-oxo hexamer, [Th6O8(H2O)n]8+. Strongly acidic solutions are required to stabilize the hydrated thorium(IV) ion. With increasing concentration and pH thorium(IV) hydrolyzes, first, to a dimer with double hydroxo bridges, then to a tetramer with the thorium(IV) ions forming a diamond (represented by two dimers merged together) . Finally, at pH value close to precipitation of thorium(IV) oxide/hydroxide, a hexamer is formed with the thorium atoms forming a rhomboctahedron. Potentiometric studies suggested a hexamer composition [Th6(OH)x(H2O)n]24-x, x = 14 or 15. However, the rhomboctahedral structure prevents for sterical reasons such a large number of hydroxide groups to be bound. Instead 7-8 oxo groups are bound to thorium ions as from proton activity point of view 16 hydroxo groups are equivalent to 8 oxo groups, making it impossible to distinguish between e.g. Th6(OH)168+ and Th6O88+ complexes. A compilation of reported solid state structures of actinoid(IV) compounds with oxygen donor ligands show a strong correlation between the An-O bond distance and the coordination number . EXAFS studies of uranium(IV), neptunium(IV) and plutonium(IV) ions in aqueous solution have reported accurate An-O bond distance, but the coordination numbers were less accurate and often overestimated. The hydrated tetravalent actinoid ions in aqueous solution all seem to be nine-coordinated .
1. Torapava, N., Persson, I., Eriksson, L., Lundberg, D.: Inorg. Chem. 48, 11712 (2009)
2. Rand, M., Fuger, J., Grenthe, I., Neck, V., Rai, D.: Chemical Thermodynamics of Thorium, Eds. Mompean, F. J., Perrone, J., Illemassène, M., OECD Nuclear Agency Agency, Data Bank, F-92130 Issy-les-Moulineaux, France, North Holland Elsevier Science Publishers B. V., Amsterdam, The Netherlands 2008, and references therein.
(Swedish University of Agricultural Sciences)
Study of reaction of CmO<sup>+</sup> and CmOCl formation in chloride melt by spectroscopic method20m
Molten chlorides have more high radiation resistance than aqueous and organic media. This fact is of significant importance because curium has a high specific activity. And, correspondingly, it can be used for partitioning of curium from waste before its vitrification. Data on thermodynamics of formation for oxygen-containing curium compounds in chloride melts was obtained by authors  with using of potentiometric titration. This work is devoted to more precise definition of these date by using of spectroscopic method. It is obtained spectrum of Cm3+ and CmO+ complex in melt NaCl-2CsCl-CmCl3 at 550, 600 and 650оС over argon atmosphere and different partial pressure of HCl/H2О. It is demonstrated appearance of peak for CmO+ complex at range of 358nm as a result of three different reactions, leading to formation of oxide ions in melt. Dependences of Cm3+ и CmO+ concentration on partial pressure of HCl/H2О are obtained. From these experimental data dissociation constants of CmO+ and CmOCl are calculated.
1. A.G. Osipenko et al. Study of Reaction of Curium Oxy-Compound Formation in Molten Chlorides// Radiochimica Acta 97, 227-230 (2009).
(Research Institute of Atomic Reactors)
Synthesis, structure and properties of synthetic trogerite (UO<sub>2</sub>)3(AsO4)<sub>2</sub>∙12H<sub>2</sub>O20m
Synthetic trogerite (UO2)3(AsO4)2∙12H2O (henceforth only ST) can be obtained by direct mixing of uranyl nitrate and arsenic acid solutions in equivalent ratio 3:2. In this case the following competitive reactions become possible:
UO2(NO3)2 + H3AsO4 + 4Н2О<->HAsUO6∙4H2O(s) + 2HNO3 (uranoarsenic acid formation)
3UO2(NO3)2 + 2H3AsO4 + 12Н2О<->(UO2)3(AsO42∙12H2O(s)+6HNO3 (synthetic trogerite formation)
The acidity increase results in uranoarsenic acid formation while its decrease essentially enhances a contribution of triuranyl diarsenate hydrates formation. The reaction temperature is also an important factor. The partial dehydrated ST and the intermediate crystallohydrates mixture are formed in the case of the synthesis temperature increase. For the reasons described above synthetic trogerite has not so far been obtained in the form of an individual crystal compound, free of any impurity phases. Its X-ray data and crystallographic characteristics are unknown. In this work the ST synthesis technique is proposed. Its dehydration and thermolysis were investigated. Structure and properties of synthetic trogerite were studied by X-radiography, IR-spectroscopy, X-ray fluorescence analysis, and scanning calorimetry. Our research has shown that dehydration is the only temperature caused transformations in the range of 20-800°С. In the interval 50-200°С trogerite loses eight molecules of water and transforms into well known (UO2)3(AsO4)2∙4H2O. The both crystallohydrates with crystal lattices built of coordination polyhedrals belong to many-membered family of the uranium (VI) compounds having the layered structural type. Layers are formed by pentagonal bipyramids UO7, connected by the general edge to produce continuous chains and combined by tetrahedrons AsO43-. Opposite layers of tetrahydrate are strongly connected by the covalent bonds, forming chains (O3)As-O-U(O5)-O-As(O3). The length of such chains determined the interlayer distances that is equal 8.782. It is not enough long chain for similar bonding of opposite layers located on 11.079 in UO2(AsUO6)2∙12H2O. Therefore bonding of layers in trogerite is not rigid and occurs as the system of H-bonds, formed by H2O molecules making a coordination environment of interlayer atoms of uranium (VI). Three H2O molecules in UO2(AsUO6)2∙4H2O exhaust coordination possibilities interlayer atoms of U(VI) in its pentagonal bipyramid.Three H2 O molecules in UO2 (AsUO6 )2 ∙4H2 O exhaust coordination possibilities interlayer atoms of U(VI) in its pentagonal bipyramid. Fourth H2O molecule is located in zeolite similar cavities, isolated and p
(Nizhny Novgorod State University named after N.I. Lobachevsky)
Thermochromatographic investigation of <sup>113</sup>In, <sup>125</sup>Sb and <sup>125m</sup>Te in quartz columns20m
Investigation of chemical properties of super heavy elements (SHE) produced in 48Ca induced nuclear fusion reactions with actinide targets [1-4] represents a challenging task for chemists world wide. In the present research an experimental determination of dHads. of carrier-free 113mIn, 125Sb and 125mTeO2 species on quartz surface was performed.
Lighter homologues of SHE elements 113mIn(T1/2=99 min), 125Sb(T1/2=2.7582 y) and 125mTe(T1/2=57.40 d) were prepared by using neutron irradiation facilities at PSI. For that purposes 0.5 g of nat-Sn were irradiated at the SINQ-NAA at PSI for 2 h. The irradiated sample was used as source for thermochromatographic investigations with quartz as stationary surface. Different experimental conditions (carrier gases, gas mixtures and flow rates) were used to investigate of chemical behaviour of indium, antimony, and tellurium species. Specially designed gradient oven allowed to achieve a temperature gradient in the range between 1300 °C up to -140 °C.
The interaction of metallic antimony and indium with quartz surfaces was investigated using a highly purified hydrogen gas to exclude trace amounts of water and oxygen. The entire thermochromatography column was encapsulated in a steel tube. The gas had to pass a Ta getter (1000°C) before hitting the tracer source deposited on Al2O3 and heated up to 1300°C. Afterwards, the released isotopes were transported again over a hot Ta getter. This setup supposed to ensure the elemental state for the quite reactive antimony. Reproducibility of obtained data was achieved by several repetitions of the experiment at the same conditions. It was found that deposition temperature Sb in elemental state is 580 0C, what is the in good agreement with literature data, whereas deposition temperature for In is rather higher (Tdep.=710 °C) than it was reported . After data collecting, Monte-Carlo simulation approach  was applied to obtain the adsorption enthalpy of the species on quartz surfaces at zero surface coverage (dHads). Calculated enthalpy of adsorption for In was -235 kJ/mol and for Sb was -205 kJ/mol. Using H2/H2O gas mixture it was possible to determine deposition temperature of 113In(OH) (Tdep.= 320 °C) and 125Sb(OH)3 (Tdep.= 360 °C). Such a deposition temperature results in dHads(InOH)= -145 kJ/mol and dHads(Sb(OH)3)= 155 kJ/mol. The interaction of tellurium species with quartz surfaces investigated using O2/H2O gas mixture. 125mTeO2 was deposited at 590 °C resulting in an enthalpy of adsorption dHads(TeO2)= -205 kJ/mol. The data obtained The data obtained in the previous research will be useful for the design of experimental set-ups for gas chromatographic experiments with real superheavy elements, especially E113-E115.
Authors kindly appreciated the financial support by SNF.
 Yu. Ts. Oganessian et al., J. Phys. G 34, R165-R242 (2007)
 M.Schädel Angew.Chem. Int. Ed. 45, 368 (2006)
 R. Eichler et al., Nature 447, 72-75 (2007)
 R. Eichler et al., Angew. Chem. Int. Ed. 47(17), 3262-3266 (2008).
 R. Eichler et al. Radiochim. Acta, submitted (2009)
 B. Eichler JINR Comm. 1972
 Zvara I. Radiochim. Acta 38, 95-101 (1985)
Thermodynamic study on the U(VI) complexation with “aliphatic” and “aromatic” di-carboxylic acids by micro-calorimetry20m
The thermodynamics of complex formation of U(VI) with oxydiacetic acid (ODA), thiodiacetic acid (TDA), iminodiacetic acid (IDA), isopthalic acid (IPA), 2,5-frandicarboxylic acid (FDA) and dipicolinic acid (DPA) were studied by the micro-calorimetric titration technique. So far, extensive data on stability constant have been obtained and summarized in databases for a variety of combinations of actinide ions and complexants which could be found in the geosphere to predict the migration behavior of actinides in deep underground for the safety assessment of radioactive waste disposal. However, enthalpy and entropy data of actinide elements are scarce in comparison with stability constants. These data are indispensable not only for understanding of the reaction mechanism but also for the estimation of stability constants at elevated temperatures outside the range of 20-30 °C by the extrapolation from those at a room temperature with using thermodynamic models. Following our previous study reporting thermodynamic data (ΔG, ΔH and ΔS) of complexation of 8 di-carboxylates with U(VI) , this paper presents the thermodynamic quantities of U(VI) complexation with three “aliphatic” di-acetic acids and three “aromatic” di-acetic acids. Those ligands have a different center atom between two carboxylic groups, i.e., oxygen for ODA and FDA, sulfur for TDA and nitrogen for IDA and DPA, which may coordinate with a metal cation. The obtained thermodynamic quantities are compared with those of U(VI) complexation with glutaric acid (GA) for the discussion of the effect of structural difference, i.e., aliphatic- and aromatic structure and types of central atom in the ligands on the complex formation thermodynamics.
From the thermodynamic quantities, i.e., ΔG, ΔH and ΔS determined by the potentiometric and calorimetric titration techniques, it is indicated that these reactions are mainly driven by the entropy change while the enthalpy change is not promoting the progress of the reaction. The ΔG, ΔH and ΔS of 1:1 IDA complex show remarkable difference from those of GA complex, while those of ODA and TDA complex are almost equal to those of GA complex. ΔG of 1:1 IDA complex with U(VI) was 30 kJ/mol larger than that of GA complex, which is generally referred to the chelate effect of the ligand. Our calorimetric measurement has revealed that this “chelate effect” should be ascribed to the “entropy effect” since the entropy change (T*ΔS) of IDA complex was 50 kJ/mol larger than that of GA complex. The origin of this large entropy effect is discussed in the presentation with the help of structural information of the complex calculated using density functional theory (DFT).
 A. Kirishima, Y. Onishi, N. Sato and O. Tochiyama, Radiochim. Acta 96 (2008) 581–589.
(Institute of Multidisciplinary Research for Advanced Materials, Tohoku University)
Poster Session - Radionuclides in the Environment, RadioecologyGallery
Age dating of the hot spring waters in Korea using natural radionuclides20m
The use of radioactive isotopes as a groundwater-dating tool plays an important role in assessing the dynamics of groundwater systems, essential for the characterization of water resources and planning its exploitation. In hydrogeological studies the application of radioisotopes with a short half-life (below 100 year) is limited in dating old groundwater. However, they can be extremely helpful in solving another type of question such as the identification of mixing between old and young groundwater systems. Within the environmental radioisotopes, 3H cannot be detected in waters more than approximately 50–60 years old due to the short half-life (t1/2=12.32 year). Among the radioactive isotopes with a half-life greater than 1 ka, 14C (t1/2 = 5730 year) represents the most important tool in groundwater dating. This radioisotope is present in the atmosphere, soil, aquifer matrix, etc.
Using these two radioisotopes, the age of the hot spring waters in Korea were estimated. And also, some other natural radioisotopes, Ra and U, were analyzed to know the characteristics of the hot spring waters.
Most hot spring waters are founded in granite region in Korea and the Mesozoic granites at the southern part in the Korean Peninsula are divided into two groups, Jurassic Daebo-granite and Cretaceous Bulguksa granite. High temperature hot springs more than 40°C occur in the above granite areas. Therefore, fifteen hot spring waters were collected and the contents of 3H, 14C and other radionuclides were determined. Tritium concentration in hot spring waters were very low, therefore, they were concentrated using the Ni-Ni electrolytic enrichment method. And it was analyzed using low background liquid scintillation counter. Dissolved carbonate was precipitated with BaNO3 to BaCO3 form and it was reacted with phosphoric acid to produce CO2. Finally, CO2 was converted graphite. After then, it was analyzed using AMS.
Tritium in the most hot spring samples could not detected and it was ranged <0.5-1.31 TU. And 14C contents were ranged 2.62-94.13 pMC(%). From the 3H and 14C analysis, we found some hot springs are mixed with recent groundwater and hot spring water aged from 490 years to 33680 years.
DrYoon Yeol Yoon
(Korea Institute of Geoscience and Mineral Resources)
Background level of radioactive isotopes around a L/ILW disposal facility before it started operation at Bátaapáti, Hungary20m
The new Hungarian National Radioactive Waste Disposal Facility was established in the granite of the Mórágy Block Mountains to store low and intermediate level radioactive waste (L/ILW) originating from the Paks Nuclear Power Plant. The safe operation of the radioactive waste disposal facilities requires a long-term environmental monitoring to gain information about the radiation properties of the site together with the radiation exposure of the personnel and the environmental media. Before the start of the operation of the facility the environmental characteristics of the site and its vicinity, i.e. the so-called zero level was determined.
The determination of the zero level of the nuclear facilities is inevitable as the evaluation of the measurement data in the course of the operation should be related mainly to this zero level. In the course of the measurements the monitoring of the environmental elements i.e. air, soil, water (springs, streams, precipitation), fall-out, wash-out, plant and animal samples was performed from several points of view. From the samples collected radiocarbon, tritium, strontium-90, gamma emitters, gross alpha, gross beta and field gamma measurements were carried out.
The results are obtained before of the operation of the facility, they can approximately be considered as the Hungarian background data.
(Institute of Nuclear Research of the HAS, Debrecen, Hungary)
Characteristics of concentration correlations for the pairs of <sup>238</sup>U/HCO<sub>3</sub><sup>-</sup>, <sup>234</sup>U/HCO<sub>3</sub><sup>-</sup>, <sup>226</sup>Ra/<sup>238</sup>U, <sup>228</sup>Ra/<sup>226</sup>Ra, <sup>226</sup>Ra/HCO<sub>3</sub><sup>-</sup>, <sup>228</sup>Ra/HCO<sub>3</sub><sup>-</sup>, <sup>210</sup>Po/<sup>238</sup>U, <sup>210</sup>Po/<sup>226</sup>Ra, <sup>228</sup>Th/<sup>232</sup>Th, <sup>228</sup>Th/<sup>228</sup>Ra, <sup>228</sup>Th/HCO<sub>3</sub><sup>-</sup> and <sup>210</sup>Po/<sup>210</sup>Pb in drinking water20m
Some important naturally occuring a and b radionuclides in seventeen brands of drinking water samples collected in Italy were determined. The mean activity concentrations (mBq L-1) of the radionuclides in the water samples were almost in the order: 26±36 (234U) > 21±30 (238U) > 8.9±15 (226Ra) > 4.8±6.3 (228Ra) > 4.0±4.1 (210Pb) > 3.2±3.7 (210Po) > 2.7±1.2 (212Pb) > 1.4±1.8 (224Ra) > 1.1±1.3 (235U) > 0.26±0.39 (228Th) > 0.0023±0.0009 (230Th) > 0.0013±0.0006 (232Th). Based on the HCO3- concentrations and the radionuclide concentrations in the analysed waters, correlation analyses were made, and statistical positive correlations were found among the pairs of 228Ra/226Ra, 226Ra/HCO3-, 228Ra/HCO3-, 210Po/238U, 210Po/226Ra, 228Th/232Th, 228Th/228Ra, 228Th/HCO3- and 210Po/210Pb in drinking water.
(National Institute of environmental protection and reasearch)
Cs, Pu and Am sorption to natural clay and their various components: laboratory experiments and modeling20m
Natural clay and iron minerals of complex composition are reactive mineral phases which can affect retardation and transport of radionuclides in the environment. Therefore, it is important to understand and quantify sorption of radionuclides on them. Sorption of Cs, Pu(IV), Pu(V) and Am(III) at trace concentrations on three well characterized samples of Triassic clay as a function of pH and composition of solution and contact time was studied. Sorption experiments were also performed with three iron oxide minerals found in the clay mineral coatings and microorganisms (bacteria and fungi) isolated from the clay and groundwater samples with the aim of better understanding the effects of various natural clay components on the speciation and sorption behavior of radionuclides. The character of bonding of Cs, Pu and Am to the clay samples was analyzed by sequential extraction (SE). Solvent extraction techniques (using TTA, HDEHP, DBM and PMBP), ultrafiltration and alpha spectrometry as well as ICP-MS were employed to characterize the oxidation states of the plutonium species in liquid and solid phases.
The results have indicated that iron oxide coatings play an important role in binding of Pu(IV) on the clay, whereas ion exchange and CaCO3 were found to be responsible for the binding of Am(III). The coatings also affected Cs sorption from solutions of variable ionic strength. Sorption experiments with microorganisms indicated that bacteria and fungi can exert different effect on the sorption behavior of Pu. Kinetic data evaluated by kinetic models derived for six different control processes mostly indicated a sorption mechanism controlled by Pu or Am diffusion in the inert layer on the surface of clay. Corresponding kinetic coefficients were determined. Surface complexation modeling of the sorption dependence on pH using a two-site surface complexation model showed high affinity of all the minerals for Pu(OH)3+ at pH > 4. Iron oxide minerals also sorbed Pu(OH)40: goethite at pH>8, hematite at pH=7-9 and magnetite at pH > 5.5. Am3+ and Am(NO3)2+ were found to be the most selectively sorbed species on all the minerals from NaNO3 solutions in the pH range of 3.5-5, whereas AmOH2+ and Am(OH)2+ were sorbed to a different extent on different minerals at pH 5-9.
The stability constants obtained by modeling have indicated that the sorption affinity of the clay for Pu is higher than that of the iron oxides studied, while the sorption affinities for Am are mutually comparable. In addition, it has been found that Pu is much more selectively (i.e. strongly) bound than Am on all the minerals studied. This well corresponds with the higher exchangeability of Am found by SE and can explain its higher mobility in the environment.
The research was supported by the Ministry of Education and Science of the Republic of Lithuania and the Lithuanian State Science and Studies Foundation projects V-19/2009, NKS-B SPECIATION project (2008-2009), FP7 RECOSY, grant No 212287.
(Institute of Physics, Savanorių ave 231, Vilnius, LT-02300, Lithuania)
Determination of strontium-90 in foodstuff20m
The Nuclear and Technological Institute (ITN) has the legal responsibility to carry out the environmental radiological monitoring at a national level. This survey was planned to provide relevant information on radioactivity levels in different components of the ecosystem (atmosphere, aquatic and terrestrial environments). In what concerns the terrestrial environment the evaluation of the strontium-90 (90Sr) concentrations in food samples has been performed through analyses of milk, completed meals, meat and vegetables. Strontium-90 (90Sr) is a radioactive isotope of strontium, with a long half life (28.8 years) that could be taken by man through food chain transfer due to its biochemical similarity with calcium. A method based on the separation of 90Sr by extraction chromatography and beta determination by Liquid Scintillation Counting technique was used for strontium analysis in food samples. The trials were carried out using 7g of ash samples, and then dissolved in concentrated nitric acid. Following additional precipitation steps the sample is loaded onto a column with 3 grams of commercial Sr-resin. This resin is specific to Sr ions and enables a rapid and simple separation of strontium from calcium, potassium and many other elements. The column is rinsed with 8M HNO3 and 3M HNO3 and after this two washing steps, the strontium retained in the column, is stripped at the end with 0.05M HNO3. The strontium solution eluted is collected in a beaker and the chemical yield was determined by gravimetric method. The strontium precipitate is dissolved with 8 mL of 0.1M HCl and added to 12 mL of the Ultima Gold LLT scintillation cocktail. The 90Sr activity was determined after 90Y ingrowths in the channel region 250-800 keV using a counting time of 120 minutes. Validation trials to evaluate the accuracy and the precision of the method were performed using 90Sr spiked samples. The method has been applied to the 90Sr determination of completed meals, meat and vegetables. Results of validation trials and food analysis will be presented and discussed in this paper.
(Nuclear and Technological Institute/ Radiological Protection and Safety Unit)
Distribution of natural radionuclides and <sup>137</sup>Cs in the sediments of a Mediterranean fjord-like embayment, Amvrakikos Gulf, Greece20m
Five small sediment cores were collected from the seafloor of the Amvrakikos Gulf for the study of the spatial and downcore distribution of natural radionuclides and 137Cs in the sediments. Amvrakikos Gulf is a shallow (< 65m) marine embayment lying on the west coast of Greece having a surface of some 405 km2 and a coastline length of 256 km. It is separated from the open Ionian Sea by a beach barrier complex and is connected to the open sea through a narrow channel, 600 m wide and less than 8 m deep. Amvrakikos Gulf receives the freshwater inputs of the Arachthos (2202 x106 m 3 yr -1) and Louros (609x106 m3 yr -1) rivers at its northern shoreline. The Gulf is characterized by a general two-layer type of stratification in the water column and is considered as the only Mediterranean fjord. Sediment samples were analysed for specific activities of 238U, 232Th 226Ra, 232Th, 40K and 137Cs together with grain size and Corg.
238U and 226Ra concentrations range from 37.2 to 124.0 and 8.5 to 27.2 Bq kg-1 with an average value of 62.1 and 17.9 Bq kg-1 respectively. The concentrations of 232Th and 40K range from 11.2 to 46.5 Bq kg-1 and 238 to 892 Bq kg-1 with an average value of 36.6 and 710 Bq kg-1, respectively. The activities of 232Th and 40K reported in the present study are comparable to those of the world average as reported by UNSCEAR, 2000. On the contrary the reported 238U activities are significantly higher than those of the world average (UNSCEAR, 2000).
The value of the 226Ra/238U ratio ranges from 0.09 to 0.66 with an average value of 0.35 showing disequilibrium between the two radionuclides in all sediment samples. The disequilibrium can be ascribed to the weathering of phosphorites of Epirus (at the northern margin of Amvrakikos Gulf) as well as to the high phosphate fertilizers inputs due to the intensive application of fertilizers in the surrounding agriculture areas. It is well known that phosphorites and phosphate fertilizers are characterized by high 238U concentrations.
The spatial distribution of 238U, 226Ra, 232Th and 40K, in the surface sediments of the Amvrakikos Gulf shows a clear increasing eastward trend. Maximum activities were observed at the eastern deep basin, while minimum values were found at the western basin of the Gulf.
The man-made radionuclide 137Cs was found in measurable concentrations (5.2-20.2 Bq kg-1) in all surface sediments (0-5 cm). The higher specific activities of 137Cs were found in the deeper sediment layers (8-44 cm) than in the surface layer. The high content of the clay minerals and organic matter found in the sediments of the Amvrakikos Gulf play very important role in the high level of 137Cs. Moreover, the elevated specific activities of 137Cs in the deeper sediment layers (44cm) suggest a high sedimentation rate for the Amvrakikos Gulf.
(DIVISION OF INORGANIC, PHYSICAL AND NUCLEAR CHEMISTRY, DEPARTMENT OF CHEMISTRY, UNIVERSITY OF PATRAS, GREECE)
Distribution pattern of NORM in Red Sea shore sediments and their relation to non-nuclear industries20m
The Red Sea is a deep semi-enclosed and narrow basin that has an intensive non-industrial activities on and near its shore. Oil exploration, phosphate mining and trading, navigation activities and intensive touristic activities are considered as non-nuclear pollution sources. They could impose a serious radiological and ecological impacts on the Red Sea marine environment. Both oil and phosphate related activities could increase the concentration of Naturally Occurring Radioactive Materials – NORM such as 238U series, 232Th series and 40K. Forty representative shore sediment samples were collected from the Egyptian Red Sea shore, from Shuqeir to Marsa Alam City region. Activity concentration of 238U, 232Th, 40K were measured using ICP-MS analytical techniques. Previous study showed the possible impact of industrial activities on the activity concentration of NORM in shore sediment. This study will investigate such relationship and the distribution pattern of NORM in relation to the elemental composition of the shore sediment.
(King Saud University)
Environmental monitoring of nuclear materials for safeguards purposes before decommissioning of nuclear facilities20m
A comprehensive environmental monitoring and analysis is very important before the decommissioning of a nuclear facility to assure the database for reveal undeclared clandestine nuclear activities.
Experiences in the process and sampling concerning decommissioning are not yet available in Hungary because the facilities have not still accomplished the end of their lifecycle.
Decommissioning is the final phase in the lifecycle of a nuclear installation and is to be considered as part of a general strategy of environmental restoration after the final suspension of the industrial activities.
The first research reactor in Hungary will need to be decommissioned over the next 10 years therefore the environmental monitoring will be necessary before the commencement of the process. The international regulation and the European Union also specify the environmental monitoring and an environmental impact study before the decommissioning procedure.
The development of a comprehensive environmental monitoring system including sampling strategy and method development for the analysis of environmental samples, originating from the vicinity of the Hungarian nuclear facilities has been begun at the Institute of Isotopes.
The developed method was tested by analysis of real samples. Environmental samples and its nuclear material content were analyzed in the near of a Hungarian nuclear facility.
(Institute of Isotopes of the Hungarian Academy of Sciencies)
Further results in search of transuranium isotopes in effluents discharged to air from nuclear power plants20m
In this work we present data on transuranium isotopes in effluents (quarterly, since 2006 half-yearly determined activity concentrations of 238Pu, 239,240Pu, 241Am, 242Cm and 244Cm in discharged effluents, annual discharged activities of individual radionuclides) discharged to air from 7 stacks in 2004-2009. In the effluents discharged to air from one stack low-level activities of transuranium isotopes were present throughout the studied period. Transuranium isotopes had been discharged to air from this stack also in previous years since 1996 when defect in the cladding of a fuel element and consequent contamination of the primary circuit occurred. In the effluents discharged to air from another stack transuranium isotopes were present only in some monitoring periods of studied years. We could not prove transuranium isotopes in the effluents of the other stacks up to 2006. The transuranium isotopes in discharged effluents were registered in the second half-year of 2006. In further years (2007-8), especially low-level 241Am was found in these effluents.
(National Radiation Protection Institute)
Investigations on seepage waters of the test site Gessenwiese by TRLFS20m
Nils Baumann*, Thuro Arnold
Forschungszentrum Dresden-Rossendorf e. V., Institute of Radiochemistry, P.O. Box 510119, D-01314 Dresden, Germany
*Tel.: +49 (351) 260 2076, Fax: +49 (351) 260 3553, Email: email@example.com
The test field “Gessenwiese” was installed on a leaching heap at the former uranium mining area Ronneburg (western Thuringia) for investigations in acid mining drainage and in heavy metals retention, especially uranium (Grawunder A. et al. 2009). The uranium speciation in seepage water of the Gessenwiese was determined by TRLFS. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) posses some superior features, above all a very high sensitivity for fluorescent heavy metal ions. The predominance of TRLFS compared to other spectroscopic techniques, e.g. XRD and IR was showed in Baumann N. et al. (2008) in analyzing the speciation of U(VI) in a thin layer of an alteration product formed on depleted uranium.
TRLFS analyses were carried out to compare it in a later stage with the uranium speciation in plants, which grow on that grassland and may take up uranium contaminated water. The uranium content in the seepage water sam-ples was 75.1 and 291 ppb, respectively, and both samples delivered an evaluable fluorescence signal for TRLFS. The positions of the six peak maxima from these signals are in both water samples in concordance with data for uranium sulfate species published in the literature, e. g. in Geipel G. et al. (1996) at 477, 493, 513, 537, 562 and 591 nm. Moreover, the time-resolved fluorescence signals of both water samples possess a mono-exponential decay, indicating the presence of one main species. These two characteristics, i.e. positions of peak maxima and lifetimes revealed without doubt that the uranium speciation in the seepage water is dominated by uranium (VI) sulfate species.
TRLFS measurements with plant compartments (e.g. roots, leaves, shoots) which grow in association with the seepage water will be carried out in future investigations. Samples could be obtained from the plant compart-ments by centrifugation as cell sap, or as solid milled plant compartment sample and subsequently analysed by TRLFS. The reactivity and toxicity of uranium depend on the speciation of heavy metals (Carrière et al. 2005) and accordingly have to be considered as important possible risk factor as uranium may enter economic plants and eventually arrives in the food chain.
Grawunder A. et al. Chem Erde-Geochem. 69 5-19 (2009)
Baumann N. et al. Environ. Sci. Technol. 42 8266-8269 (2008)
Geipel G. et al. Radiochim. Acta 75 199-204 (1996)
Carrière M. et al. Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms 231, 268-273 (2005)
Long-term monitoring of radioactivity in environmental of the City of Moscow20m
Moscow is the historical center of the atom project of the former USSR.
Radioecological assesment of the territory of Moscow has been provided in compliance with the conception and program of comprehensive radioecological monitoring of the Moscow city, approved by the Moscow Goverment.
The methodology of the envitonmental monitoring is based on long-term determenation of concentration of the major dose forming radionuclides in natural environment and some components of metropolitan megapolis accumulated by mobil and stationary systems. Such an approach ensures to monitor variations in temporary-and-spatial distribution of radiation parameters of the environmental objects as well as to identify the areas where radiation values are abnormal ones and to assess the radiation situation both at separate sites and in the city in general.
Monitoring data are used in Radiation-Hygiene Passport of the Moscow city.
(Scientific and production enterprise "Radon")
Methods and results of the main negative factors of KOSHKAR-ATA tailing pond with impacts on environment20m
Ecological situation of Mangystau oblast (Kazakhstan) started aggravating in 1990s with exploration of uranium ore, oils, mineral raw and creation chemical industry in Mangyshlak without paying due attention to environmental issue. According to available data the worsening is connected to number of ecologically unfavorable problems.
The tailing pond KOSHKAR-ATA, representing the drain-free settling pool for industrial, toxic, chemical and radioactive wastes, as well as for ordinary domestic drains, is 5 km northward to Aktau (Mangystau oblast), which is situated on the shore of the Caspian sea. Industrial, toxic and radioactive waste, solid sediments of unpurified ordinary domestic drains form a part of the Aktau dwelling region have been drained into the tailing pond since 1965 and have been stored there up to now.
Thus, continuous and long-term contamination of the lands around the tailing pond KOSHKAR-ATA and their vegetation unambiguously forces to consider regional ecological situation as critical. That is why it is very important to take immediate measures in order to reduce sequences, eliminate the reasons and sources of contamination and restore natural characteristics of environmental.
Field investigations are performed in the scope that assures detailed radiometric surveying of the shore zone of the tailing pool KOSHKAR-ATA and its coast.
The field investigations included: there was performed mapping of current outline of the coast-line/water edge of the toxic waste storage; there was performed footpath gamma-surveying of the shore exposed surface (EDR was measured in 150 points) and there was mapped the gamma-field distribution; there was assessed the volume activity for radon over the shore exposed surface of the tailing pool.; there were performed the detailed gamma-surveying in the vicinity of surface burial of radioactive waste (RW); there were performed the monitoring measurements of aerosols at 10 stations; there has been performed species identification and taken samples of vegetation at the waste storage in places where soil fill had been previously performed; that was done to estimate radionuclide accumulation rate by vegetation and their further wind transfer.
Analysis showed that there is increased content of such radionuclides as thorium-234, radium-226, led-214, bismuth-214, led-210, uranium-235, thorium-227 in bottom sediment samples.
There were studied presence forms for isotopes of thorium, radium, 210Pb, 238U. Led-210 is considered as one of the most biologically hazardous natural radionuclides, even more radio-toxic as 90Sr. Considerable part of 210Pb (up to 53%) is associated with acid-soluble form what demonstrated its high migration abilities. Mobility series for 210Pb (in %) looks like: acid-soluble forms (40.2%) > exchange forms (11.7%) > water soluble forms (0.4%).
Analysis of obtained results shows that there is higher contents of led-210 in samples taken within the sectors; this is particularly so for the sector “Caspii.”
(Institute of Nuclear Physics)
report for book of abstract
Microbial activity impact on the change of Pu oxidation states20m
The potential of migration of Pu at contaminated sites and also from the waste repository depends on the Pu environmental behavior determined by its chemical speciations. Depending on the ambient conditions plutonium exists in several oxidation states due to the low differences in the oxidation – reduction potentials between the oxidation states 1. The geochemical and physical characteristics of the environment (mineralogy, pH, chelating agents, redox conditions, temperature, and humidity) and microbial activity play an important role in plutonium behavior in various systems. Under appropriate conditions the activity of microorganisms could affect the chemical nature of plutonium due to changing redox condition and biotransformation of its oxidation states. The oxidation states control the solubility, complexation and thus the geochemical action of Pu 2. The direct enzymatic or indirect nonenzymatic interaction of microbes with plutonium could considerably cause its solubility or immobilization because of the formation of stable complexes with metabolites and organic degradation products.
This study is aimed at investigations on the change of plutonium oxidation states due to activity of aerobic bacteria and fungi.
Both microorganisms and fungi were isolated and identified from samples collected from the low-level radioactive waste repository. Aerobic bacteria Bacillus mycoides, Rhodococcus lutes, unidentified Gram-bacteria, and fungi Paecillomyces lilacinus, Absidia sp., Gliocladium virens have been detected in dust. Oxidized and reduced Pu was tested by two radiochemical procedures 3,4. One procedure (co-precipitation with NdF3) only differentiates between reduced Pu [Pu (III) and Pu (IV)] as well as oxidized Pu [Pu (V) and Pu (VI)]. The second (extraction chromatography) procedure was designed to differentiate between Pu (III) and Pu (IV). The amount of reduced and oxidized Pu was determined by measuring α activity after radiochemical separation.
The results of the experiment have shown that all bacteria and fungi can very slightly alter oxidation states of plutonium due to their microbial activity. No more than 8-9 % and 15 % of Pu (IV) was reduced to Pu (III) by bacteria during one hour and 24 hours of the interaction respectively. Pu by fungi was reduced no more than 1%.
1. Francis A. J., Dodge C. J., Ohnuki T.: J. Nucl. Radiochem. Sci. 8, No 2, 121-126 (2007).
2. German K. E., Firsova E. V., et al.: Radiochemistry, 45, 250 (2003).
3. Ketterer M. E., Hafer K. M., Mietelski J. W.: J. Radioanal. Nucl. Chem. 73, 183 (2004).
4. Moreno L., Vaida N., Danesi P. R., La Rosa J. J., Zeiller E., Sinojmeri M.: J. Radioanal. Nucl. Chem. 226, 297 (1997).
(INSTITUTE OF PHYSICS)
Natural radioactivity in Tunisian and in some imported phosphate fertilizers used in Tunisia20m
The radioactivity concentrations of 226Ra, 232Th and 40K in different phosphate
fertilizers, triple superphosphate (TSP), diammonium phosphate (DAP),
monoammonium phosphate (MAP) and in phosphoric acids produced and used in the agricultural soils in Tunisia were measured. Other exported and used phosphate fertilizers in the country were also subject of radioactivity concentrations measurement and they consisted in some NPKs. Gamma spectrometry using a high purity germanium (HPGe) detector was used for the measurement. It was found that generally the Tunisian fertilizers contain the highest activity concentrations with the exceptions of 40K. TSP contains the highest concentration of 226Ra (186.2 14.5 Bq/kg) and of 232Th (33.7 3.5 Bq/kg). The highest amount of 40K was found in one type of NPK (9969.5 Bq/kg). The radium equivalent index was calculated for all the analysed fertilizers and was found to be the highest in the imported NPKs samples (the maximum value was about 775 Bq/kg) because of their high content in 40K. For the Tunisian fertilizers the maximum radium equivalent index was about 238 Bq/kg in TSP.
(UR-MTDN, National Center of Nuclear Sciences and Technolgies)
Naturally existing <sup>210</sup>Po in human and dog hair samples20m
More than 100 samples of human hair and 15 samples of dog fur were collected from Pomeranian area for polonium analysis. The 210Po concentration in analyzed hair samples ranged from 0.33±0.02 to 12.84±0.80 mBq.g-1 dw (mean value is 3.41 mBq.g-1).
The highest 210Po activity values were found in hair sample collected from men had rich fish diet and smoked about 20 cigarettes per day. The lowest 210Po concentration was found in hair sample collected from a lady who did not consume fish and did not smoke cigarettes. The lowest amounts were also found in children’s hair (0.43±0.03 and 0.84±0.08 mBq.g-1 dw) who did not eat much fish and lived at homes free of cigarettes. In the case of a child living at home where exposed at cigarettes this concentration was much higher – 4.02±0.37 mBq.g-1 dw.
Among dogs fur the highest 210Po concentration was found in 7 years old dachshund dog – 4.48±0.54 mBq.g-1 dw, but the lowest 210Po concentration was found in 3 years old staffordshire bull terrier bitch – 1.96±0.26 mBq.g-1 dw.
The authors would like to thank to the Ministry of Sciences and Informatics for the financial support under grant DS/8460-4-0176-10.
(University of Gdańsk)
Origin of <sup>129</sup>I in the environment of Slovenia20m
I-129 is considered as a global pollutant and its role as a global tracer to follow the dissemination of radionuclides from a source point such as nuclear fuel reprocessing plants increases. The natural I-129/I-127 isotopic ratio in the order of 10E-12 was significantly influenced by releases of anthropogenic I-129 to the environment. The ratio of I-129/I-127 in the marine environment has increased to 10E-11 – 10E-10, and in the terrestrial environment to 10E-9 – 10E-7, even 10E-6 in the vicinity of nuclear fuel reprocessing plants. Anthropogenic I-129 predominates in the biosphere, soil and in upper layers of the oceans, therefore it can be expected that the isotopic ratio I-129/I-127 is increasing in these compartments of the ecosystem.
At the Josef Stefan Institute we have developed a radiochemical neutron activation analysis method (RNAA) for the determination of I-129 in environmental samples and the detection limit of the method is 5∙10E-14 g I-129 / g solid sample. The developed method was used to trace I-129 in the environment of Slovenia. From marine environment seawater, alga, thorny oyster and sediment samples were analyzed and from terrestrial environment precipitation, soil and pine needles. The results found were in the range from 7.2 to 120.8 • 10E-7 Bq/kg for precipitation, up to 75 • 10E-4 Bq/kg for soil, from 0.1 to 2.12 • 10E-4 Bq/kg for seawater, from 7 to 62 • 10E-4 Bq/kg for thorny oyster and from 17 to 73 • 10E-4 Bq/kg for brown alga Fucus virsoides (Donati) J. Agardh., which is endemic to the Adriatic Sea. The content of I-129 in marine sediment and pine needles samples analyzed till now was below the detection limit of the method.
The data of this study represent a survey of I-129 in the environment of Slovenia. The most likely source of I-129 are nuclear fuel reprocessing plants in La Hague and Sellafield, which are known to be the major sources of I-129 in the environment of North Europe. I-129 is transferred to the atmosphere and washed out to the marine and terrestrial environment of Slovenia by precipitation, so it is of atmospheric-precipitation origin.
(Institute Jožef Stefan)
Plutonium 241 – importance and ways of determination20m
Plutonium 241 is the only beta emitting plutonium isotope formed by a nuclear reactor operation. In contrast to the other ones, its half life is relatively short (about 14 years). Emitting beta radiation, it decays to another important radionuclide, Am-241. Hence the activity of americium 241 is still increasing in the area of Chernobyl, Ukraine.
Nuclear fission leads to higher-order activities of the Pu-241 than of the other plutonium isotopes. On the other hand, the beta energy of this radionuclide is only 20 keV, which, in addition with no gamma radiation, falsely decreases its importance. For example, determination of isotopes activity ratio between Pu-241 and other isotopes can lead to the recognition of the isotope mixture source.
Plutonium speciation in the southern Baltic Sea sediments20m
Wet and dry atmospheric fallout from nuclear weapon tests is one of the most important sources of plutonium in Baltic Sea. The other sources: plutonium releases from spent fuel facilities in Sellafield (UK) and Cap de la Hague (France) are less important. Since April 26, 1986 there is a new source of plutonium – Chernobyl plutonium, which should be taken under note in estimation of its radiological effects on the environment. In marine environment plutonium exists on III, IV, V and VI oxidation state and in the Baltic Sea 99% of total plutonium is deposited in sediments.
In this study 6 different chemical forms of plutonium (the fraction dissolved in water, connected to carbonates, connected to oxides, complexed with organic matter, mineral acids soluble and the rest) in sediments from the delta of Vistula River, Gdańsk Bay, Gdańsk Deep and Bornholm Deep were determined.
The distribution of 239+240Pu in analyzed sediments samples was not uniform and depended on its chemical form, depth and geomorphology of the sediments. The highest 239+240Pu concentrations were found in muddy sediments of Gdańsk Bay at 8-9 cm layer while the lowest, 10 times lower than in Gdańsk Bay, near the delta of Vistula River. The lowest plutonium concentrations were found in the lowest layers (below 22 cm).
According to all analyzed fractions the biggest amount of 239+240Pu in all sediments was found in the fraction connected to carbonates: the delta of Vistula River – 34%, Gdańsk Bay – 42%, Bornholm Deep – 35%. In sediments of Gdańsk Deep plutonium was mostly connected to fraction soluble in mineral acids (40%). Significant 239+240Pu amount was also connected to organic matter (29%), but the lowest amount of plutonium was in fraction dissolved in water.
The authors would like to thank to the Ministry of Sciences and Informatics for the financial support under grant DS/8460-4-0176-10.
(University of Gdańsk)
Polonium <sup>210</sup>Po and uranium <sup>234</sup>U and <sup>238</sup>U in phosphogypsum and surface water at waste dump in Wiślinka from Phosphoric Fertilizers Industry of Gdańsk and their accumulation in plants20m
Phosphogypsum refers to the gypsum formed as a by-product of processing phosphate ore into fertilizer with sulfuric acid. They are radioactive due to the presence of naturally occurring uranium and radium in the phosphate ore and enriched in natural polonium 210Po, while the uranium radionuclides (234U and 238U) tend to be in waters around waste dump. The migration and distribution of uranium and polonium radionuclides in analyzed water samples are not uniform.
All analyzed phosphogypsum samples contained higher 210Po activity in comparison with uranium radionuclides.
The values of uranium and polonium concentration in water with immediate surroundings of waste heap are considerably higher than in the waters of the Martwa Wisła River. The activity ratio of 234U/238U is approximately about 1 in the phosphogypsum and between 0.92-9.99 in the water of retention reservoir and pumping station, while in the water from the Martwa Wisła River is slightly higher than 1. Polonium and uranium concentrations in water samples of the Martwa Wisła are relatively low in comparison with value in retention reservoir and pumping station near phosphogypsum waste heap. This suggests that radionuclides could be leached from dumping site to the surrounding environment.
The major source of polonium and uranium in plants is wet and dry atmospheric fall containing the soil and the air dust from the phosphogypsum waste dump and also accumulation through the root system. The highest uranium and polonium concentrations were found in older part of grasses (yellow oat-grass, meadow foxtail, moneywort), turned for atmospheric fall for a long time.
The authors would like to thank to the Ministry of Sciences and Informatics for the financial support under grant DS/8460-4-0176-10.
(University of Gdańsk)
Radiation monitoring method features of contamination areas ageing in landscape20m
The aim of this work is generalizing experimental researches data received in zone of Chernobyl trace in 2007 in Bryansk region in order to automorph, transit and accumulation landscapes. Variabiliy of 137Cs levels in shown at the 3 experimental sites.
(Institute of global climat and ecology)
Radioactivity concentration in soil samples taken from region of Banja Luka (Bosnia and Herzegovina)20m
Surface soil samples (0-15 cm) were collected from the region of Banja Luka (Bosnia and Herzegovina), in order to evaluate their radioactivity. Concentrations of radionuclides in samples were determined by γ-ray spectrometer using HPGe detector. The obtained results of uranium and thorium series as well as potassium K-40 and Cs-137 activity concentrations are discussed. The radioactivity levels are compared with the results form other countries.
Radiocesium activity concentration measurements in game meat as a tool for monitoring radioactive contamination in wildlife and ensuring radiological safety for consumers20m
An increased level of caesium radioisotopes was noted in many foodstuffs after the Chernobyl disaster. The radiocaesium activity concentrations may remain high in products such as game meat, wild mushrooms, and forest berries. Therefore, an official monitoring of radiocaesium in game meat was established by Polish Veterinary Inspection. Generally, consumption of game meat in Poland is low. However, in hunters’ families this sort of food can contribute a large portion of meat to a diet. Moreover, some quantities of Polish game meat are exported to many countries. Meat samples of wild boar, red deer, and roe deer were taken at game processing facilities by veterinary inspection officers and then transported to laboratories for analyses. Radiocaesium activity concentrations were determined by gamma-ray spectrometry using scintillation (NaI(Tl)) detectors. The Cs-134 activity concentrations were negligible (below MDA) in all the samples analysed. Generally, the Cs-137 activity concentrations varied between and among the animal species even in the same region ranged from MDA values to some hundreds Bq/kg. The effective dose, which general population in Poland received from consuming game meat, may be considered very low with the exception of hunters’ families. Assuming the mean annual game consumption of 20 kg in hunters’ families and the mean effective dose of 0.23 µSv per kg (two year studies), an individual in the most exposed group may receive the effective dose of 4.6 µSv. In conclusion, consumption of local game meat is safe in terms of contamination with radiocaesium and radiological protection.
(National Veterinary Research Institute, Department of Radiobiology, Pulawy, Poland)
Radioecological impacts of NORM fractionation in phosphate rock beneficiation processes20m
Phosphate rock beneficiation processes (crushing, screening, washing, magnetic separation and wet screening) aims to increase the phosphorus content of the run-of-mine (ROM) ore. It starts with the ROM ore and ends with the wet rock, and different rejects (by-products). These by-products have potential environmental hazards due to their content of Naturally Occurring Radioactive Materials – NORM especially uranium-238 series. They have also potential industrial and agricultural useful applications due to their physicochemical properties such as their relative high content of phosphorus, clay and iron. Representative samples of ROM ore, wet rock, and beneficiation processes by-products (wet screening, magnetic separation, slim, and clay and dolomite rocks) were collected. Natural radionuclides (238U, 235U, 232Th, 40K, 210Pb, 210Po) were measured using γ-ray spectrometer, α particle spectrometer and ICP-MS analytical techniques. Radiologically, internal hazards index, external hazard index, representative level index, γ absorbed dose rate and occupational dose equivalent due to inhalation were calculated. Potential hazards due to beneficiation processes and their by-products were discussed. Some of the by-products could have potential useful applications such as clay rock and slim for agricultural soil reclamation. The aspects of these useful applications were discussed.
(King Saud University)
Radioecological situation in areas of uranium legacy of Uzbekistan20m
Vasidov A.,Salikhbaev U.S., Kist A.A., Raduyk R.I.
Institute of Nuclear Physics, Tashkent, Uzbekistan
Central Asia Countries were the main supplier of the uranium in former USSR and one of them was the Republic of Uzbekistan. As a mining activity and conversion of uranium ores had resulted to formation large amounts of radioactive wastes, that had have make an exigency problem, as provide a radiation safety on the territories of uranium mines, tails and are close lying settlements.
In this work, the results of measurements of the radon concentrations on the territories former uranium mines and nearby populated sites are presented.
For radon measurements were used electronic units of RRA-01M (Russia) and PRM-145 (Sloveniya), acting on semiconductor detector and scintillation cells, respectively. Both units records alpha particles of daughter radionuclide Po-218. For reliable estimation of the annual efficient doses (AED) of inhabitants and its lifetime fatal risks (LFR) a long time registration alpha particles of radon by nuclear solid track detectors CR-39 (Italy) have been carried out. Dwellings and worker premises were selected on free basis and radon exposure with CR-39 was two and three months at summer and winter time.
In settlement Yangiabad, volume activity of indoor radon were - 60-100 Bk/m3, values of AED of radon for inhabitants 1.7-2.8 mSv/year and LFR estimation at (1.3 – 2.3) x10-4.
In village Chorkesar in windless and matutinal period radon activity on territory of the mine reached 70-100 Bk/m3 on distance 50-70 cm from ground. Indoor radon level are range from 60 to 450 Bk/m3 and 1.7-12.6 mSv/year for AED, (1.3– 10.5)x10-4 for LFR at summer and from 250 to 1200 Bk/m3 and 7.0-33.6 mSv/year for AED, (5.6-27)x10-4 LFR at winter time.
Speciation of <sup>129</sup>I and <sup>127</sup>I in seawater profiles from the Kattegat and Baltic Sea20m
Long physical half life, long residence time in the marine environment and continuous releases from nuclear fuel reprocessing plants make 129I a suitable tracer for the study of marine geochemical cycle of stable iodine and conversion mechanism of iodine species by speciation analysis of 129I and127I. Up to date there are few data on chemical speciation of 129I in seawater and no 129I chemical speciation analyses in seawater profile was reported. The converting mechanism of iodine chemical species is still unclear.
In the present work, depth profile samples of seawater collected from the Kattegat Belt Sea and Baltic Sea are analyzed for 129I, 127I as iodide, iodate by using anion exchange chromatography coupled with accelerator mass spectrometry (AMS), inductively coupled plasma mass spectrometry (ICP-MS) respectively.
A relatively high concentration of 129I (2-18 x 1010 atom/L) was found in the Kattegat comparing with that in the Baltic Sea (<2 x 1010 atom/L). The results show that in the Baltic Sea the concentrations of 129I, 127I increase with depth and salinity, while the same trend does not occurred in the Kattegat Basin. In Baltic Sea the predominant species of iodine is iodide while in the Kattegat the ratio 129I-/129IO3- is 1-2. Along the water profile, the atomic ratios of 129I-/127I- and 129IO3-/127IO3- decrease from the northern Kattegat to the central Baltic Sea.
Speciation analysis of 129I in seawater profile is indispensable for a better understanding of geochemical cycle of stable iodine and the converting mechanism of iodine species in the marine environment.
(Radiation Research Department, Risø National Laboratory for Sustainable Energy,Technical University of Denmark- DK-4000 Roskilde, Denmark)
Speciation of <sup>129</sup>I and <sup>127</sup>I in soil and sediment samples20m
Iodine is a biophilic tracer element with thirty-four isotopes including one long-lived isotope, 129I (15,7 My), and one stable isotope, 127I. Toxicity, mobility, bioavailability, bioactivity, and the uptake of iodine in environment are governed by its chemical speciation and the soil or sediment conditions. It is therefore important to identify and quantify different physicochemical contaminant species.
In this work, a sequential extraction procedure combined with accelerator mass spectrometry (AMS), and inductively coupled plasma mass spectrometry (ICP-MS), respectively, was applied for investigation of 129I and 127I in different physicochemical forms in soil and sediment samples. The fractionation allowed identification of water soluble, exchangeable, carbonate, oxides, iodine bound humic acid, iodine bound fulvic acid and iodine bound humin forms. This is the first study to identify humic acid, fulvic acid and humin bound 129I. A Danish soil sample, a soil reference material (IAEA-375), an anoxic sediment sample collected from Helvik Fjord (South Norway) and an oxic sediment sample collected from the Barents Sea (Russia) were investigated.
The results of the work show that in the investigated samples, 129I bound to organic matter accounted for more than 50% of the total iodine. Approximately 90% of the 129I is bound to organic matter and oxides, and 10% was found in the readily exchangeable fractions.
Speciation analysis of 129I in soil/sediments is indispensable for a better understanding of bioavailability, mobility, bioactivity, uptake and toxicity of iodine in the environment.
(Radiation Research Department, Risø National Laboratory for Sustainable Energy,Technical University of Denmark – DTU)
Specific activity of <sup>40</sup>K in drinking water in Slovenia20m
The European legislation (Council Directive 98/83/ec) requests the member sates to control the radioactive contamination of drinking water. As a part of these measurements γ-ray spectrometric measurements are performed. Samples of 50 L of water are evaporated and the residue after evaporation is measured. Typically, 20 g – 40 g of residue is obtained.
Since by γ-ray spectrometry activity concentrations of radioactive isotopes emitting γ-rays can be determined also the concentration of natural 40K in the samples is measured. The measurements of activity concentration of 40K are relatively easy since it radiates at an energy, where no interference with other γ-ray emitters occurs.
Drinking water in Slovenia is gained mainly from the ground water. Therefore the concentration of potassium in drinking water reflects the properties of the rock of the aquifer as well as the geochemical conditions there. The activity concentration of 40K in drinking water may bear information on the circumstances in the aquifer from where drinking water is extracted.
In the contribution the correlation between the activity concentration of 40K in drinking water and the potassium concentration in the soil will be presented. The correlation will be discussed in terms of the geological properties of the aquifers and the level of the water table.
(Student of Jožef Stefan International Postgraduate School, Ljubljana, Slovenia)
State and migratory ability of uranium and radium in the soils of Belarus20m
Alpha-emitting uranium and radium are present practically in all ecosystems and together with their decay products play an important role in formation of internal radiation dose of population from natural radionuclides. This dose depends essentially not only on the content of radionuclides in environmental components, but also on the radionuclides’ state and migratory ability in a soil medium.
The aim of this work is the determination of uranium and radium species in soils and natural soil waters and evaluation of radionuclide migratory ability in different soils.
The objects of investigation were samples of 0-10 cm layers of soils from different regions of Belarus.
The natural system “solid phase – pore water of soil” have been used for determination of uranium and radium migratory active forms in the soil samples. The potentially mobile forms and potentially biologically available forms were determined using accordingly the model systems "soil – 1 mol/L solution of ammonium acetate" and "soil – 1 mol/L solution of HCl".
Radionuclide species in soil waters were investigated by passing of the water samples through the filters of different pore size with subsequent separation of complex radionuclide forms of different electrostatic charge using the method of ion exchange chromatography. Radionuclide activity in the samples was determined by radiochemical analysis with radionuclide identification by α spectrometer SOLOIST U0450 with low-background detectors 576 A 600 RV.
The specific activities of the soil samples are 4.8–22 Bq/kg for 238U and 4.5–29 Bq/kg for 226Ra. It was found that both 228U (84–94%) and 226Ra (77–91%) are mostly in the fixed forms (insoluble in 1 mol/L HCl). The radionuclide rate in migratory active forms for 238U was 0.06–0.7 % and for 226Ra 0.01–1.0 % of the total radionuclide content in soil samples. The rates of potentially mobile radionuclide forms are 3.1–9.3 % for 228U and 1.8–4.5 % for 226Ra but the radionuclide rates of potentially biologically available forms are respectively 6–16 % and 9–23 % of the corresponding radionuclide content in the soil samples.
The main part of 228U and 226Ra of natural soil water samples (65–91 %) is in dissolved state or in composition of fine colloidal (less than 0.45 μm) particles. The radionuclides in this state are the most mobile in environment. In composition of this portion of natural water samples 226Ra is mainly in the cationic form, but 228U coexist in anionic, cationic and neutral complexes. In organic soil waters, the anionic uranium complexes prevail, but in mineral soil waters, the cationic and neutral complexes are the main portion of radionuclide.
The received information allows estimating the uranium and radium rates in forms participating actively in radionuclide distribution in the soil medium as well as evaluating the radionuclide reserves in forms that can enter the soil solutions and participate in processes of biogeochemical radionuclide migration in ecosystems. The results of investigation are the basis for differentiation of soils according to migration ability of uranium and radium and for modeling of radionuclide transferring in the environment.
(Belarus State University)
Study of <sup>7</sup>Be concentration in the north of the Spain20m
From the Sun and interstellar spaces of the universe the primary cosmic radiation comes to the Earth. These cosmic rays interact with the nuclei of atmospheric constituents, producing an interaction cascade and secondary reaction and also produce a number of radioactive nuclei known as cosmogenic, 7Be between others as a result of spallation reactions.
In Bilbao (north of Spain) there is a high flow rate atmospheric sampler which belongs to the Radiological Surveillance Network of the Autonomous region of the Basque Country. Among the radionuclides present in the air aerosols 7Be is found.
The network is in operation since October 2001 and so a long record of 7Be measurements is available.
To study the behaviour of 7Be in air, the recorded values have been considered as a succession of data what is usually known as a Time Series. It is made up of 4 components: trend, cyclical component, seasonal component and irregular component.
The cyclical component is not fully developed because the studied period (2001 – 2009) is shorter than the solar cycle (eleven years period), which is the ultimate cause of that component.
A trend and seasonal components have been determined and finally an irregular component has been observed. This is caused by occasional events, such as rain, which washes 7Be out depositing it onto the ground. However, it has been found that the atmospheric concentration of 7Be is negligibly affected by rain.
(University of the Basque Country)
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Temperature effects on emanation of radon from rock to water and on its partition between water and air20m
Emanation of radon (222Rn) from rock and partition of radon between water and air are important parameters, so its evaluation is of significance in the study of radiation protection, environmental geochemistry, climate change and so on. In this study, emanation of radon from rock particles (1-2 mm) to water and partition of radon between water and air by temperature of 0, 10 and 20 °C have been determined using an equilibration partitioning in a closed system (EPICS) method. Specific activity of radon in the rock particles used here were 4.990 ± 20 Bq/kg. The results show that emanation of radon from rock and partition of radon on air increase with increasing the system temperature, however partition of radon on water slightly decreases with increasing temperature. In conclusion, radon emanation from bed rock or soil and partition of radon between water and air is controlled by temperature change, which in turn is also governed by climate change.
DrKil Yong Lee
(Korea Institute of Geoscience and Mineral Resources)
Testing automatic groundwater sampling unit by the isotope analytical and dissolved ion tests20m
Automatic water sampling unit was developed in Herteleni Laboratory of Environmental Studies of MTA ATOMKI for monitoring the radioactive emission from nuclear facilities into the groundwater. The efficiency of existing and renewed geometry units and the reproducibility of survey data have been examined in the course of this work. A testing method was developed for this purpose, and ion binding efficiencies of ion exchange resins were analysed for different ion concentrations. These efficiencies have to be taken into consideration when we estimate the amount of the contamination got into the groundwater on the basis of the proportion of ions gained back from the resin. The model tests were executed under controlled laboratory circumstances. These circumstances were tried to be formed into facts true to nature.
It has been found during the chain of tests that the sampling unit is suitable for well reproducible sampling. It can be told that all tested geometrical lay-outs are utilizable and work with proper efficiency in small/low range of concentration as well. Taking the different efficiencies into consideration the activities can be corrected in the case of every element if it is necessary. A correcting factor should be introduced during the 14C anion exchanging sampling because samples taken by exchanging have systematically lower radio carbon content than the reality has. We are working on continuing the tests. The gamma activity measurement of existing gained back cation samples and giving the exact value of 14C correction can give more reliable picture and direction to developing existing and possibly new systems.
(Institute of Nuclear Research of the HAS, Debrecen, Hungary)
The accumulation of transuranic elements of the Chernobyl emission by meadow vegetation of the zone Chernobyl NPP20m
The Chernobyl accident was accompanied by release into the atmosphere of a large number of radionuclides with long half-life. As a result of exposure to biological objects most dangerous in the long term are included in the composition of the fuel particles transuranic elements (TUE-239, 240Pu, 241Am), are a - emitters. Radionuclides with different half-life and environmental features included in the terrestrial ecosystems in different ways and become widespread in the ecosystem.
To build realistic models of behavior of transuranic elements necessary to carry out a focused analysis of the features of the distribution of long-lived isotopes of radioactive elements in various types of ecosystems. As a result of this work was to study the behavior of long-lived radionuclides of the Chernobyl genesis in meadow phytocenosis.
To characterize the level and species specificity of the accumulation of 239,240 Pu and 241Am vegetation calculated rates of accumulation, are numerically equal to the ratio of specific activity of TUE in overground phytomass of plants and their concentration in soil (Bq / kg).
Fluctuation of values of specific activity phytomass of 239,240Pu was observed in range from 0,11 to 0,77 Bq / kg and 241Am - from 1,20 to 21,0 Bq / kg. Income TUE in plants depends on soil conditions, time of selection and climatic conditions. The experiments were conducted for several years, these have a very large scatter, but a number of peculiarities.
As a result, studies were identified vegetation types that are most active in the most actively absorb TUE. So, for 239,240Pu established a number - Oenothera biennis L.> Helichrysum arenarium (L.) Moench> Vicia cracca L.; for 241Am - Koeleria gracilis Pers.> Oenothera biennis L.> Elytrigia repens L. > Lysimachia vulgaris L. > Cytisus ruthenicus Fisch.
Biological characteristics and life cycle of plants will undoubtedly affect the value of radionuclide accumulation, but the spread of values of accumulation factor on one site within the same family has definite boundaries, characteristic of the family.
We found that the contribution of 241Am contamination of vegetation is predominant among TUE, which indicates its greater biological mobility than isotopes of plutonium.
This should be taken into account when deciding whether the use of forage resources in polluted in varying degrees, regions. The significant growth of 241Am activity requires consideration of this effect when calculating the dose for the public.
(NATIONAL ACADEMY OF SCIENCES OF BELARUS State scientific institution "Institute of Radiobiology")
The estimation of radon activity in multistoreyed buildings of industrial iron-ore region20m
N. Karnaukh, L. Ishchenko
Some regions of Ukraine are Radon dangerous. Geologic peculiarities of Krivbass region, available mining tunnels, historic habits in housing construction, decreased morbidity on malignant tumor of population specify the actuality of “Radon” problem studying in iron-ore region which should be consider at estimation of radiation exposure to population.
By our own researchings it is determined that as a rule Radon is accumulated in basement and on the ground floor of buildings. Though significantly high doses of Radon EEVA were registered in the upper stores of five-storied dwelling houses of 1968-1970 years of construction.
Thus level of Radon-222 EEVA in five-storied dwellings was registered as follows: on the ground floor it was 33 - 113 Bq•m-3 , on the first floor – 21-63 Bq•m-3 , on the second floor – 43-69 Bq•m-3 , on the third – 22-85 Bq•m-3 , on the fourth floor – 67-93 Bq•m-3 .
During measuring the daily variation of Radon content in the air of the dwellings it was determined that Radon volume activity depended directly on ventilation regime in the dwelling. Thus the Radon level was measured in two the apartments of the fourth floor with two different ventilation regimes – with regular opening of the window and without this procedure.
In the first case the family was of three adult persons, engaged in job. Radon level was measured in the kitchen with regular ventilation using window. This level was 67 Bq•m3. Effective dose of Radon exposure was 2,9 mSv•year-1 . Radon level was measured in the room with vacuum ventilation provided by the house design. This level was 93 Bq•m-3 .
In the second case the residents of the apartment were three adult persons, engaged in job. Radon level was measured in the room with vacuum ventilation provided by the house design. This level was 93 Bq•m-3 . Effective dose of Radon exposure was 4,0 mSv•year-1 .
In both cases exposure doses were significant in spite of additional ventilation.
Radon entering the upper stores is caused by lack of ventilation. The rate of air near ventilation holes was < 0,1 м•s1 . This peculiarity displays during heating the apartments, when windows are closed hermetically and the air inflow diminish. As a result the contingent of population exposured to radon increases.
(Ukrainian Research Institute of Industrial Medicine, Krivoy Rog, Ukraine)
Translocation of radioactivity from substrate to macromycetes in some mining areas20m
The present study follows the extent of translocation radioactivity from substrates of uranium and sulphur mining area to the macromycetes spontaneously occurred during 2008-2009. To this end, radioactivity measurements (gross α+β, 226Ra, and 137Cs) on both macromycetes and their substrates were made. The resultants obtained were confirmed by FT-IR spectroscopy, evidencing the presence of characteristic bands around of 910 cm-1, corresponding to the asymmetric stretching vibration of the uranyl unit and to the interaction between the UO22+ ions and the group belonging to various cellular components.
(“Al.I. Cuza University”, Department of Chemistry, 11 – Carol I Blvd., 700506 – Iasi, Romania)
Uranium and long-lived decay products in water of the Mulde river20m
The Mulde River, a tributary of the Elbe River in east-central Germany, is formed by the confluence of the Freiberger Mulde and the Zwickauer Mulde, both rising from the Erzgebirge. Running north, the two rivers merge near the small village of Sermuth to form the Vereinigte Mulde, which flows into the Elbe River near Dessau. The Erzgebirge or Ore Mountains are a mountain range, which is located at the border between Saxony / Germany and the Czech Republic. Due to its rich uranium deposits the area of the Zwickauer Mulde River became the world’s third largest uranium supplier during the time of the Warsaw Pact. Today, clean-up of the legacy of the former mining and milling industry represents one of the largest remediation projects in progress.
Being part of the project ‘Transport and availability of uranium and decay products in alluvial soils of the Mulde River’, this work deals with the investigation of radionuclides in the water of the Mulde River. The radionuclide contents of water and sediment indicate the overall condition of a river, with the water showing a faster response to variations. 20 samples were collected along the course of the rivers Zwickauer Mulde and Vereinigte Mulde between the city of Aue in the Erzgebirge and the Saxon border. For comparison, further samples were taken at the headwaters of the Zwickauer Mulde, along the Freiberger Mulde and the Leine River (Hannover), respectively. A total of 26 samples of water were taken and analysed for uranium, polonium-210, and radium-226 content using alpha-spectroscopy, liquid scintillation counting, and mass spectroscopy, respectively. The work focuses on present contaminations deriving from tributary streams or river sediments and the detection of changes as a result of remediation effects. Own results are compared with results from earlier investigations, carried out from 1991 to 1993.
(Leibniz University Hanover; Center for Radiation Protection and Radioecology)
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Use of selected chelating agents to mobilize radiocesium from the body20m
Examinations were carried out to compare the effects of Prussian Blue (PB), Ca-gluconate, and Na-citrate on removal of radioceasium from male Wistar rats. The animals were randomly divided into 5 groups of 10 animals each. Radioceasium was administered by intragastric intubation to all tested rats for 5 concecutive days with a daily dose of 20 kBq. Animals in group 1 (the controls) were administered only ceasium-137 chloride whereas animals in groups 2 to 5 were subjected to the same radioceasium schedule as rats in group 1 and then treated as follows: groups 2 and 3 were given PB by gastric intubation at a dose of 20 mg in 0.5 mL of distilled water 1 hr or 1 hr and 5 hr, respectively, after ceasium-137 contamination whereas rats in group 4 after each PB treatment were subsequently injected ip for 5 consecutive days with a daily dose of 20 mg of sodium citrate and calcium gluconate in 0.5 mL of distilled water. Rats in group 5 were treated similarly to rats in group 4 but without PB administration. Animals were killed 6 days after termination of the experimental protocol. The whole-body retention of ceasium-137 was measured in a well type scintillation counter. Mean values were compared by Student's t-test. Prussian Blue, Ca-gluconate and Na-citrate failed to produce any unfavourable effects on body weight gains and organ to body ratios of the liver, kidneys, heart, and testes in all rats tested. Control rats retained 71.2% of administered radioceasium in the whole-body. Fivefold and tenfold administration of PB or fivefold treatment with PB plus 5 injections of Na-citrate and Ca-gluconate decreased significantly the whole-body retention of radioceasium to 49.7%, 38.4%, and 43.2%, respectively. On the other hand, fivefold treatment with Na-citrate and Ca-gluconate (witout PB treatment) faild to decrease radioceasium retention in comparison to that in the controls. The present results showing a high efficiency of Prussian Blue in removal of radioceasium from animal bodies are in accordance with earlier reports of others. On the other hand, no effects of Ca-gluconate and Na-citrate injection on radiocaesium mobilization from the body were in contrast to the opinion that citrate and gluconate enhance the removal of radioceasium from animals.
(National Veterinary Research Institute, Department of Radiobiology, Pulawy, Poland)
High specific activity <sup>177g</sup>Lu for metabolic radiotherapy: deuteron cyclotron vs. nuclear reactor30m
This work is focused on production of Lu-177g for uses in metabolic radiotherapy of tumors, due to the appropriate average beta- energy and gamma rays suitable for detection by gamma-camera and SPET: t1/2 = 6.734 d, b- 100 %, Ebeta-max = 489.3 keV, <E> = 163 keV, main Eg = 113 and 208 keV. It is one of the most promising beta- emitters for small cancers. The production methods are either direct neutron capture Lu-176(n,g)Lu-177(m+g) on (60-70 %) enriched Lu-176 target (sigma-th = 2 + 2100 10E-28 m^2, plus a contribution of epithermal neutrons from resonance peaks), with a lower specific activity AS than the theoretical carrier-free one: AS(CF) = 4.05 GBq.microg^-1, or neutron capture on highly enriched Yb-176, followed by beta- decay Yb-176(n,g)Yb-177 -> Lu-177g (sigma-th = 3.1 10E-28 m^2). Due to the long half-life Lu-177m is relevant, for rad-waste and dose to the patient and medical personnel. The second method produces a high AS NCA Lu-177g, whilst the first one a lower AS CA mixture of both, diluted in stable Lu isotopic carrier. Thus, in the latter case the Lu-177g is contaminated by the long-lived radionuclidic impurity Lu-177m. Several commercial samples of reactor produced Lu-177 were submitted to accurate measurement of both decay patterns and radionuclidic purity vs. time by using HPGe and LSCS. The measurement of the isomeric ratio of Lu (direct neutron activation) and the absence of other Lu RNs (indirect neutron or deuteron activation) allows identifying the production method adopted. In case of direct Lu-176(n,g) route, it was evidenced that - at administration time - the typical amount of the long-lived Lu-177m was of the order of 0.01 %. The experimental t1/2 for Lu-177g (6.724 ± 0.006 d) is in very good agreement with the reference value taken from the literature of 6.734 d.
An alternative method is based on deuteron activation of Yb-176, by (d,p) reactions followed by decay of the short-lived Yb-177 and direct (d,n) reactions as well. Deuteron activations have been carried out at JRC-Ispra Cyclotron (K=38) of EC, with deuteron beams up to 19 MeV.
To conclude Lu-177g can be produced in no-carrier-added form, by either neutron activation on enriched Yb-176 or by deuteron irradiation on very highly enriched Lu-176, both followed by decay of Yb-177. In both cases a AS value could be very close to the CF one, after selective radiochemical separation of Lu from Yb target. It is remarkable that Yb-177 decays solely to the ground level of Lu, leading to a very high radionuclidic purity Lu-177g, not contaminated by the long-lived metastable radioisotopic impurity Lu-177m. A much higher value of radionuclidic purity is achievable (theoretically 100 %) in case of direct Yb-176(d,n)Lu-177 route, whose effective threshold is at 13 MeV.
Several activation of thin Yb targets by deuterons led to the conclusion that a maximum thin-target yield for Lu-177g of 246 MBq.C^-1.MeV^-1 is achievable (sigma-max = 250 10E-25 m^2) at 12.5 MeV, on 100 % Yb-176 target. Our data will be compared with the data taken from the literature for the two neutron routes.
Finally ET-AAS and NAA were used to determine chemical purity and AS of the products.
Prof.Mauro L. Bonardi
(Radiochemistry Laboratory, LASA, Università degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate, Milano, Italy)
Production of <sup>26</sup>Al, <sup>59</sup>Ni, <sup>44</sup>Ti, <sup>53</sup>Mn and <sup>60</sup>Fe from proton irradiated copper beam dump30m
The station for pions cancer therapy was operated at PSI from 1980 to 1992. For this period the copper beam dump of the facility received a total dose of approx. 0.16 Ah of 590 MeV protons. The sampling collected about 500 g of high active copper chips that can be used for separation of exotic radionuclides. The γ analyses showed main nuclides present to be 60Co, 54Mn, 22Na, 65Zn and long lived 44Ti with a daughter nuclide 44Sc. Further analyses by LSC and AMS demonstrated that significant amounts of 26Al, 53Mn, 59Ni, 63Ni, 55Fe and 60Fe are present in the copper beam dump. The analytical results estimate that about 100 MBq 44Ti, 500 MBq 53Mn, 7 kBq 26Al, 8 MBq 59Ni and 5 kBq 60Fe are available in the collected copper chips .
Due to the high activity of 60Co, approx. 5 GBq in total, the separation should be implemented using a hot cell. The purpose of this work is to develop a simple, selective, efficient and easy method for the separation of 26Al, 59Ni, 53Mn, 44Ti and 60Fe from gram amounts of the copper beam dump.
For the separation of the exotic radionuclides from the copper beam dump, a procedure combining selective precipitation, ion exchange and solvent extraction was developed. Copper as the main matrix element interferes with the separation of all elements of interest. For this reason, after the copper dissolution in 7 M HNO3 the solution is conditioned to 1 M HNO3 and Cu (II) is precipitated selectively by saturation with H2S, while the exotic radionuclides remain in the solution. Further the solution is transferred in 12 M HCl and passed on Dowex 1x8 anion exchange column. Al and Ni are not retained and are washed out of the column with 12 M HCl. The remaining ions are eluted consequently in the following way, Mn–10 M HCl, Ti–8 M HCl, Co–5 M HCl, Cu–2.5 M HCl and finally Fe with 0.5 M HCl. Finally Al is separated from Ni on Dowex 50x4 cation exchange column and Ni is purified with Eichrom Ni resin based on the traditional dimethylglyoxime precipitation chemistry. The proposed separation procedure is easy for remote controlled implementation in a hot cell. The ion exchange separation of Ni, Al, Mg, Ti and Fe is complete and high decontamination factors for copper and cobalt were achieved.
The full scale system is installed in a hot cell where high activity levels could be handled. During the test period 13.86 g in total of the proton irradiated copper beam dump were processed for separation of 26Al, 59Ni, 44Ti, 53Mn and 60Fe. The results showed the system is operational and the radionuclides separation is selective with high chemical yield. The procedure manages as well the generated liquid wastes containing high level of 60Co activity, reducing drastically their volume.
1. D. Schumann et al., Radiochim. Acta, 97 (3) 2009
(Paul Scherrer Institut)
Optimisation of the long lived <sup>121</sup>Te contaminant in production of <sup>123</sup>I trough the <sup>124</sup>Xe(p,x) route15m
At present the preferred route for 123I (T1/2 = 13.2 h) production is bombardment of highly enriched 124Xe with 35 MeV protons and taking advantage of the cascade decay 123Cs-123Xe-123I. After irradiation the gas targets are allowed to cool for 7 h ensuring optimal in-growth of 123I from its precursors. A separation of I from all other elements is performed resulting in a nca, pure solution.
An unavoidable contaminant is 121I (T1/2 = 2.12 h) produced by 124Xe(p,α) reaction with a cross section maximum around 20 MeV.
This rather short lived radioiodine will disappear quickly from the 123I solution, but its long lived decay product 121gTe (16.8 d) accumulates and impairs the late use (several half lives of 123I after calibration date) of the solution.This situation could be improved by lowering the 121I production through limitation of the target thickness and imposing a higher exit energy.
As the only values for the 124Xe(p,α) reaction were reported by Tarkanyi et al.  at higher energy, reliable data on the excitation function need to be measured for the first time.
Highly enriched 124Xe was bombarded with protons between 13 and 37 MeV with the double aim of determining cross sections for 121I production and resolving discrepancies existing in the previously published values for production of 123Cs and 123Xe .
Here only results for 121I are presented and compared with results from different theoretical codes.
In the experimental (and production) conditions formation of 121Cs and 121Xe are impossible or extremely low (practical threshold of 1 mb at 38 MeV ).
Direct formation of 121gTe (16.8d) or 121mTe (154d) through the (p,3pn) reaction are not of importance because of the needed chemical separation at EOB+ 7 h .
The cross sections for 121I production show a practical threshold at 9.5 MeV rising to a maximum of 13 mb at 21 MeV, not in agreement with theoretical results.
From a fit to our excitation curve, production yields for short irradiations on thick targets are calculated. The 121I activity present at the optimal cooling time is then calculated for different energy degradation in the target and for different irradiation times (up to 13 h, 1 half life of 123I, saturation of 121I ).
By comparing to the cumulative produced 123I in the same irradiation conditions, the evolution of the relative activity of both 121I (decreasing in time) and 121Te (increasing in time) is calculated. By defining maximal admissible contaminations levels for late use of the 123I solution, limits on target thickness are defined.
 F. Tarkanyi et al. , Applied Radiation and Isotopes, 42, 1991, p221
 IAEA TECDOC 1211, Vienna 2001.
Radiochemical measurement of cross sections for the production of the therapeutic radionuclide <sup>193m</sup>Pt15m
The radionuclide 193mPt (T1/2 = 4.33 d), a high spin isomer, decaying by highly converted isomeric transition, emits about 33 Auger electrons per decay. It is of great potential interest in internal radiotherapy because of its suitable decay properties and platinum-complexes (like cis-platin and others) used in chemotherapy, i.e., potent antitumor agents. In order to avoid side effects of chemotherapy, it is advisable to use this radionuclide in the same chemical complex with high specific activity. So far the specific activity of 193mPt produced has been rather low due to the use of the 192Pt(n,γ) process at a reactor. In a recent study, the 192Os(α,3n) reaction was measured up to 28 MeV . The aim of the present work was to establish reliable and reproducible chemical preparation of thin targets from highly enriched osmium and to extend the measurement of excitation function of the 192Os(α,3n) reaction up to 35 MeV, where the optimum energy range was expected, and to increase the yield and the specific activity of the 193mPt at a cyclotron.
We optimized the dissolution and conversion of osmium to osmium tetroxide vapor and trapping in KOH solution, the electrolytic preparation of thin target samples of highly enriched 192Os on Ni, and the complete radiochemical separation of radioplatinum.
The excitation function of the 192Os(α,3n)193mPt reaction was measured from 26 MeV to 39 MeV using the conventional stacked-foil activation technique. Several stacks containing 99.65 % enriched 192Os targets and thin Ti and Cu foils were irradiated by 40 MeV α-particle beam of about 100 nA for 2 h at the Brussels Cyclotron. The Ti-nat(α,X)51Cr reaction induced in the Ti foil was used to monitor the incident beam intensity. After complete separation of radioplatinum, the radioactivity of 193mPt was measured by X-ray spectrometry using the Pt X-ray line of 66.8 keV. The measured count rates were converted to decay rates by correcting for the X-ray intensities, self absorption in the source, and the efficiency of the detector using the well known formula; thereafter the nuclear reaction cross section was calculated. The cross section of the 192Os(α,3n)193mPt reaction reaches a value of about 1.5 b at the maximum at about 35 MeV. It was also calculated theoretically using the compound-precompound nuclear model codes TALYS and STAPRE. The calculated values are consistent with the measured data. The optimum production of the 193mPt radionuclide by this method was found in the energy range 30 - 38 MeV; the integral yield of 193mPt being about 40 times higher than that in the energy region below 28 MeV . The results provide basic information on the production of high-quality 193mPt for therapeutic application. Tests on impurity, the yield and specific activity are underway.
 K. Hilgers, H.H. Coenen and S.M. Qaim. Appl. Radiat. Isot. 66, 545-551 (2008).
DrMd. Shuza Uddin
(Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich, D-52425 Jülich, Germany)
Radionuclides in the Environment, Radioecology 1Mirror Hall
Natural radionuclide concentrations in Austrian mineral waters20m
As an EU country, Austria has to meet the European Community guideline concerning waters for consumption; here a Total Indicative Dose of 0.10 mSv per year for all nuclides with the exception of tritium, potassium-40, radon and radon progeny, is fixed. In our investigation we measured the radium isotopes Ra-226 and Ra-228, the uranium isotopes U-248 and U-234, as well as Pb-210 and Po-210; although the latter two are radon daughters and therefore exempted from the guideline, they can contribute considerably to the committed dose due to their higher dose conversion factors.
1-1.5 L samples of brands from all over Austria were collected from different stores. Radium isotopes were separated by filtering the acidified and degassed mineral water through a Ra extraction disk containing an ion exchange resin1. Radium was eluted from the filter with EDTA. The EDTA solution was mixed with a scintillation cocktail and then counted with a low-level counter (Quantulus 1220) using pulse-shape analysis. This procedure collects also the Pb-210, which can be seen in the β-spectrum close to the Ra-228 peak.
Po-210 was spontaneously deposited from the remaining solution onto Cu planchets together with a Po-208 tracer and measured α-spectrometrically with a PIPS detector2.
After adding U-232 as a spike uranium was separated by anionic exchange and also measured α-spectrometrically after microprecipitation with neodymium flouride3.
From our measured activity concentrations we will give an estimate of the radiological impact of mineral water on consumers. Generally, the calculated annual doses to the adult members of the public are far below the Total Indicative Dose of 0.1 mSv per year.
1 F. Schönhofer, G. Wallner. Very rapid determination of 226Ra, 228Ra and 210Pb by selective adsorption and LSC. Radioactivity and Radiochemistry 12 No.2 (2001) 33.
2 WHO, World Health organisation. Methods of radiochemical analysis. Genf 1966.
3 F.D. Hindman. Neodymium flouride mounting for α-spectrometric determination of uranium, plutonium and americium. Anal. Chem. 55 (1983) 2460.
This work was funded by the Bundesministerium für Gesundheit, Familie und Jugend, Sektion III, GZ: BMGFJ-32234/0002-III/B/5/2008.
(Institut für Anorganische Chemie, Universität Wien)
Polonium (<sup>210</sup>Po), uranium (<sup>234</sup>U, <sup>238</sup>U) and plutonium (<sup>238</sup>Pu, <sup>239+240</sup>Pu) in the biggest Polish rivers20m
Radionuclides existing in the environment, both natural and artificial, are accumulated in plants and animals and transferred through the trophic chain. They are also transported with river from their catchments’ areas. The activities of polonium 210Po, uranium (234U, 238U) and plutonium (238Pu, 239+240Pu) were measured in the biggest Polish rivers with tributaries – the Vistula and the Oder – and 3 small Pomeranian rivers. The Vistula unfiltered water samples were collected from November 2002 to November 2003, the Oder and the Pomeranian samples were collected from October 2003 to July 2004 and all were measured using the α spectrometer.
The highest quantity of 210Po was transported from the Vistula catchments area to the Baltic Sea in spring and the lowest in summer, while the Oder carries the highest amounts during spring time. Annually the southern Baltic Sea is enriched in 94.5 GBq of 210Po (73.7 GBq from the Vistula, 14.8 GBq from the Oder and 6.0 GBq from the Pomeranian rivers).
In the study, the highest activities of uranium 234U and 238U in the Vistula River samples was observed in spring, the lowest in summer. The activity of uranium in the Oder was different in all analyzed seasons, the lowest however in summer. In all analyzed river samples uranium isotopes 234U and 238U are not in the radioactive equilibrium state and the values of 234U/238U activity ratio lie between 1.03-1.84. Annually the southern Baltic Sea is enriched in about 750 GBq of 234U and 238U from all analyzed rivers.
According to the Vistula River the highest quantity of plutonium 238Pu and 239+240Pu were transported to Baltic See in spring and the lowest in summer. The highest activities of plutonium 238Pu and 239+240Pu in the Oder River samples was observed in winter, the lowest in summer. Annually the Vistula River, the Oder River and the Pomeranian rivers enrich the Baltic Sea in 22.2 MBq 238Pu and 137.6 239+240Pu.
The authors would like to thank to the Ministry of Sciences and Informatics for the financial support under grant DS/8460-4-0176-10.
(University of Gdańsk)
Radiological characterization of drinking and mineral waters in Slovenia20m
It is well known that water contains dissolved radionuclides from uranium and thorium decay chains. Their concentrations are variable and depend on the nature of the aquifer rock types and the prevailing lithology. Quantitative information about the activity concentrations of critical alpha emitting radionuclides in the food and drink is important in the study of cumulative radiation effects on human life. Measurements of their levels in drinking water are therefore important to estimate the potential exposure of the public.
Due to postulation that the dose coefficient is always related to a specific radionuclide the aim of our study was to determine the activity concentrations of 238U, 234U, 226Ra and 210Po in drinking and mineral waters from different geological or lithological background areas all over the country. For determination of investigated radionuclides alpha-particle spectrometry was applied. On the basis of radionuclide activity concentration the contribution of each particular radionuclide to internal radiation doses from drinking and mineral water for different groups of people (children, adults) was assessed.
(Jožef Stefan Institute)
Prompt γ-ray activation analysis for H, B, Bi, Pb and Cd30m
Neutron Activation Analysis (NAA) is a well established method for non-destructive determination of elemental composition and the analysis of trace elements. Prompt Gamma Neutron Activation Analysis (PGAA or PGNAA) is a complementary radioanalytical technique to NAA for non-invasive investigations of samples with neutrons.
One of the main advantages of this latter technique is the easy determination of some light elements like H, Li, Be, B, C, N and S, that can not be easily determined or cannot be determined at all by NAA. Moreover, for the determination of elements like P, Cd, Gd and Pb PGAA is more effective thanks to the high neutron cross section of some isotopes that are not activated after the irradiation.
The next advantage of PGAA is the rapidity: the irradiation takes max. few hours, the data analysis can be performed on the day of measurement and the sample is not activated for a long time. Furthermore, the sample needs no preparation for the PGAA measurement.
At the first sight, the disadvantage of the PGAA to NAA are the detection limits. Compared to NAA they are usually higher, aside few exceptions, mainly in the ppm region. But speaking about PGAA, it is more correct to mention “dynamic detection limits” because they are strongly dependent on the matrix of the samples and on the background of the neutron beam (measurements are done during the sample’s irradiation).
The neutron beam guide NL4b at the research reactor Froschungsneutronenquelle Heinz Maier-Leibnitz (FRM II) in Garching bei München is dedicated to the new Prompt Gamma Neutron Activation Analysis facility.
The fingerprint of this PGAA instrument is the cold neutron flux of a very high intensity due to the elliptically tapered design of the neutron beam guide. The neutrons are focused at the sample position with a maximum thermal equivalent flux of 6.3*10^10 n/cm² s (1.7*10^10 n/cm² s using the measured mean energy of neutron spectrum, 1.83 meV). The detection system is made by two HPGe detectors, both with a standard Compton suppression system.
In this contribution few exemplary measurements of “typical PGAA elements” will be presented:
• Hydrogen is a very interesting element concerning superconducting materials and some clathrates. Its presence inside these compound can modify the material charachteristics;
• PGAA is very effective for the determination of boron. The dynamic range for this element was determined, as well as the detection limit and used for measurements in silicium wafers and nano-particles;
• 1-dimensional distribution of bismuth in lead crystals was also determined with very good statistics.
• Cadmium is another “good element” for this technique. It was analysed in some biological samples for medical research.
(Technische Universität München)
Is extraction of Fe from iron based minerals an appropriate method for determining trace elements?20m
Various trace elements in different types of iron based geological reference materials [JSS 804-1 (hematite), JSS 820-2 (limonite), SU-1 and SU-1a (iron-nickel-copper-cobalt ores)] were investigated using k0-NAA in both forms: instrumental (k0-INAA) and radioanalytical (k0-RNAA).
To avoid the interference of iron as a matrix element, firstly mineral was dissolved in aqua regia then liquid-liquid extraction procedure by diisopropyl ether (DIPE) in hydrochloric acid media was applied. Trace elements were determined using k0-INAA after irradiation of water phase. Secondly, the mineral was irradiated and than radiochemical extraction of Fe were done using DIPE and trace elements were determined by k0-RNAA in water phase.
The k0-NAA method, applied to determine the content of the investigated elements, after removal of Fe enabled to follow the distribution of 39 elements through their corresponding intermediate/medium and long half-lived radionuclides. The elimination of the matrix element lowered the detection limit for some trace elements compared to their corresponding values determined by k0-INAA in powder form and with certified values for some elements. However, the results for some elements (e.g. As, Ba, Ca, Cs, Hf, K, Na, Zn and Zr) are higher comparing to k0-INAA in powder due to the adsorption/desorption on glassware. The k0-RNAA procedure shows better agreement than k0-INAA with data obtained by k0-INAA in powder mostly due to negligible blank contribution. The results of this work will be presented and discussed.
(Jozef Stefan Institute, Ljubljana, Slovenia)
The impact of polyethylene vials on reactor channel characterization in k<sub>0</sub>-NAA20m
Reactor channel characterization is commonly performed by irradiation of bare and cadmium-covered
"fluence rate-monitors", avoiding as much as possible the use of irradiation vials/capsules and spacers for positioning
the monitors inside the channel.
However, in routine k0-Neutron Activation Analysis is generally necessary to pack the samples in polyethylene vials
prior to irradiation.
This work aims at studying the impact of polyethylene vials on the f (thermal-to-epithermal flux ratio)
and alpha (epithermal flux distribution) parameters through the bare, cadmium-covered and Cadmium-ratio methods.
The accuracy of each method will be discussed.
Recent trends in radiometrics and mass spectrometry technologies – synergy in environmental analyses30m
The dominant development in the radiometrics techniques has been the utilisation of large HPGe detectors in underground laboratories with anti-cosmic or anti-Compton shielding for the analysis of short and medium-lived radionuclides in the environment. They have included applications of high efficiency HPGe detectors (up to 200% relative efficiency to a 75 mm diameter, 75 mm long NaI(Tl) detector), often operating at least a few tens of metres underground, where the nucleonic component of cosmic rays is reduced by several orders of magnitude. In the mass spectrometry sector, applications of Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Accelerator Mass Spectrometry (AMS) for the analysis of long-lived radionuclides in the environment are the most important recent achievements. These developments in both sectors did not only considerably decrease the detection limits for several radionuclides (up to several orders of magnitude), but they also enable to decrease sample volumes so that sampling e.g. of the water column or sediments can be much easier and more effective. A comparison of radiometrics and mass spectrometry results for the analysis of radionuclides in the environment shows a reasonable agreement – within quoted uncertainties, for wide range of activities and different sample matrices analysed. 137Cs, 3H, 14C, 129I and Pu isotopes water profiles recently obtained for the Indian Ocean will be discussed in detail.
Experimental study and modelling of <sup>137</sup>Cs sorption behaviour in the Baltic Sea and the Curonian Lagoon20m
Sorption–desorption behaviour of Cs, Pu and Am in the system was studied using data obtained from different sampling campaigns in the Baltic Sea and the Curonian Lagoon in 1999-2009 as well as from short- and long-term kinetic tracer experiments using natural sea or river water and bottom sediments collected in the Curonian Lagoon or the Baltic Sea. Sorption experiments were carried out with particles of various sizes from 0.2 to 50 µm. Samples of suspended particles and bottom sediments collected during these sampling campaigns were fractionated according to the size, and association of 137Cs with solid phase was studied using sequential extraction. In addition, the in situ distribution of 137Cs between water and suspended particles of various sizes was measured and expressed as Kd. Kd values for suspended particles of > 0.2 µm size ranged from 1000 to 5500 ml/g in the near shore zone of the Baltic Sea and from 1400 to 20000 ml/g in the Curonian Lagoon. The part of 137Cs bound to 0.2-1 µm particles changed from 10% in the near shore waters to about 80% in the open sea. For all studied radionuclides Cs, Pu and Am an increase in massic activities with decrease of bottom sediment particle sizes was determined. Data obtained from tracer kinetic sorption experiments with 134Cs and bottom sediment fractions of different grain size were used for finding a suitable kinetic sorption model, kinetic constants and the corresponding equilibrium Kd values. It has been found that the modelled data best conform to the mechanism of ion diffusion through the so-called inert layer on the surface of the sediment particles. Kinetic sortion experiments with Pu(V) and Pu(IV) at trace initial concentrations were performed with the natural seawater and bottom sediments with the aim of better understanding of plutonium behaviour in the Baltic Sea. Solvent extraction techniques (using TTA, HDEHP, DBM and PMBP) were employed to characterize the oxidation states of the formed plutonium species in the liquid and solid phases. Modelling is in progress.
(Institute of Physics, Savanorių ave 231, Vilnius, LT-02300, Lithuania)
Natural radionuclides in sediments and rocks from Adriatic Sea20m
During the International Scientific Cruise to Adriatic and Ionian Seas organised by the International Atomic Energy Agency (IAEA), sediment and rock samples were collected at different locations. Sediments were sampled with grab corer at six locations in the middle and south Adriatic Sea. Rocks were collected on three islands (Palagruža, Brusnik, Jabuka) in the Adriatic Sea. In the samples, natural radionuclides U-238, U-234, Th-232, Th-230 and Ra-226 were determined. Samples were first dried, crushed and homogenised. After that, radiochemical separation procedures were applied. After radiochemical separation, samples were measured by alpha spectrometry system equipped with PIPS (Passivated implanted planar silicon) detectors. Activity concentrations of natural radionuclides in samples were from 11.7 to 27.0 Bq/kg for U-238, from 7.9 to 28.1 Bq/kg for U-234, from 13.2 to 31.9 Bq/kg for Th-232, from 17.1 to 40.9 Bq/kg for Th-230 and from 8.3 to 52.3 Bq/kg for Ra-226. In the presentation, the obtained values are discussed in detail and compared with results of similar investigations carried out elsewhere.
(Jožef Stefan Institute)
Migration ability of plutonium and americium in the soils of Polessie State Radiation-Ecological Reserve20m
One of the most important factors determining the radioecological situation in the terrestrial ecosystems is the radionuclide species in a soil medium. Radionuclide forms determine the processes of their entrance into the soil solutions, redistribution in soils, migration to the surface, ground and underground waters and spreading outside of the contaminated area.
The present work is devoted to investigation of physicochemical forms and migration ability of plutonium and americium in soils of Polessie State Radiation-Ecological Reserve (PSRER), where located the main part of α-emitting radionuclides of Chernobyl origin.
The objects of investigation were mineral and organic soils sampled in 2008 with the step of 5 cm to the depth of 25–30 cm. The forms of plutonium and americium distinguishing by association with the different components of soil and by potential for migration in the soil medium were studied using the method of sequential selective extraction according the modified Tessier scheme. Activities of 238Pu, 239,240Pu and 241Am in the samples were determined by the method of radiochemical analysis with α-spectrometer radionuclide identification.
A vertical radionuclide distribution in soils and the total radionuclide reserves in the soil profiles were established. Intensities of vertical radionuclides’ migration in the soils were estimated. It was shown that the main part of plutonium and americium is in the 0–20 cm soil layer, more often in 0-10 cm layer. Location of the radionuclide weighted mean quantity in the soils is at the depth of 3–15 cm from the soil surface. The average rate of vertical radionuclide migration of this quantity varies from 0.15 to 0.7 cm y-1 and is practically the same for plutonium and americium.
The main part of plutonium and americium in soils is in immobile forms. Radionuclide portions in water soluble and reversibly bound forms do not exceed 9.4 % of radionuclide content in the soil. In mineral soil samples, the radionuclide portion in these fractions exceeds the corresponding portion in organic ones. In both mineral and organic soils, the portion of mobile americium is higher than plutonium. The portion of biological available forms of plutonium and americium is 2.7–29 % of total radionuclide content in the soils. The higher portion of biological available forms is characteristic for mineral soil (14–29 %) as compared with that in organic one (2.7–18 %). The reserves of mobile and biologically available radionuclide forms increase with the depth of soils. The increase of radionuclide portions in mobile and biologically available forms promotes the radionuclide entrance into the soil solution and enhancing the intensity of migration processes in the soil-plant system.
The main control factors of radionuclide migration in soils under consideration are water regime and presence of radionuclide in composition of fuel particles. These factors could be more affective than radionuclide solubility in the soil waters because of some part of radionuclide transfer with the particles.
The work was fulfilled in the frame of ЕSP.EAP.SFPP 983057 Project (“Science for Peace” NATO Programme).
(Belarus State University)
Micro-scale investigations of U(VI) immobilization by cementitious materials30m
Cement-based materials play an important role in multi-barrier concepts developed worldwide for the safe disposal of low- and intermediate-level radioactive waste. Cement is used to condition the waste materials and for the construction of the engineered barrier system (container, backfill and liner materials) in deep geological repositories. The cementitious near field is subject to chemical alteration processes due to the interaction of cement with groundwater infiltrating from the host rock. A molecular-level understanding of the interaction of radionuclides with cement improves long-term predictions of radionuclide retention in cement-based repositories with regards to influences of the heterogeneity of the cement matrix and the chemical evolution of the cementitious near field with time caused by cement degradation.
In this study the speciation of U(VI), which is the dominant oxidation state under oxidizing and slightly reducing conditions in cementitious environments, was investigated by a combination of wet chemistry and synchrotron-based (micro-)spectroscopic and micro-diffraction techniques. Wet chemistry experiments were carried out to quantify U(VI) uptake by cement. Sorption isotherm measurements enabled us to distinguish U(VI) retention by sorption from solubility-controlled effects. Complementary to wet chemistry experiments, we carried out synchrotron-based X-ray absorption spectroscopy (XAS) studies on U(VI) doped crushed cementitious materials (bulk-XAS) and micro-X-ray fluorescence (micro-XRF), micro-XAS and micro-diffraction studies (micro-XRD) on U(VI) doped compact hardened cement pastes (HCP) to obtain information on the U(VI) speciation on the molecular level. Micro-scale studies provided structural information on U(VI) binding mechanisms which are essential for the development of thermodynamic models of U(VI) uptake by cementitious materials. To the best of our knowledge, the combined use of bulk-XAS, micro-XAS and micro-XRD techniques for speciation studies on U(VI) doped HCP materials is novel.
The synchrotron-based studies showed that in the cement samples with low U(VI) concentration, i.e., in the linear range of U(VI) sorption, U(VI) was predominantly bound onto calcium silicate hydrates (C-S-H). The latter phases are among the most important cement phases governing immobilization processes. The coordination environment of U(VI) was found to resemble that of U(VI) in uranyl silicate minerals under these conditions. At high U(VI) loadings, however, where U(VI) immobilization is controlled by a solubility-limiting process, a second U(VI) species was observed in addition to uranyl-silicate-like U(VI) coordination. The coordination environment of this species was similar to that of U(VI) in Ca-uranate.
This study demonstrates that C-S-H are the uptake-controlling phase for U(VI) in HCP. This finding, in combination with the observed long-term existence of C-S-H phases in an evolving cementitious near field, implies that safe disposal of U(VI) in a cement-based repository should be possible over a very long period of time.
Sorption of Ni and Eu in a multi-element system20m
At present the immobilisation of High Level Waste (HLW) in vitreous matrices followed by their burial in deep geological repository systems, composed of natural and engineered barriers to isolate the long lived radionuclides from the biosphere is the most preferred procedure. Granitic rock formations are being considered as host rocks for such geological repositories1. The study of the sorption of radionuclides onto geological media is, therefore, an important part of the safety assessment of deep geological disposal of radioactive waste. Due to the many combinations of adsorbents, data collection in multicomponent systems (MCS) is complex; therefore mathematical models have been developed to predict multicomponent (MC) sorption based on the adsorption properties of each element2. The problem of predicting adsorption based on the information of single component isotherms is still a challenge in adsorption studies. Multi-element sorption systems were examined in the last century, however, none of these studies dealt with competitive adsorption and only a few dealt with the selectivity of the sorption processes3. Several isotherm models have been used to model experimental data obtained from mixed radionuclide systems. One of the commonest of these models shown below.
• Qmix/Q0 > 1, the sorption is promoted by the presence of other
• Qmix/Q0 = 1, there appears to be no observable effect and,
• Qmix/Q0 < 1, the sorption is suppressed by the presence of other
metal ions in solution.
Static batch sorption experiments with 0.2 g of granitic rocks and different granitic minerals with 40 cm3 of non active Eu and Ni solutions have been performed in systems of single and multiple elements. Solutions were doped with 63Ni and 152Eu, acting as analogues for di- and tri-valent elements. Equilibration periods were between 7 and 10 days, after which radiometric methods (Liquid scintillation counting and gamma spectroscopy were used to determine the sorption patterns.
The results obtained showed that generally Eu sorption to the 6 granitic materials studied is affected by Ni competition, except in the case of Adamellite granite. Ni sorption to granitic materials was only not affected by the presence of Eu in solution in the case of biotite mica.
1.Murali, J., Mathur, J.N.: Sorption characteristics of Am(III) and Cs(I) on bentonite and granite. Journal of Radioanalytical and Nuclear Chemistry. Vol 254,1, 129-136 (2002).
2.Keith, K.H., Porter, C.J.,Mckay, G.: Langmuir isotherm models applied to the multicomponent sorption of acid dyes from effuent onto activated carbon. Journal of Chem Eng data. 40, 575-584 (2000).
3.Prasad, M., Xu. H-Y., Saxena, S.: Multi-component sorption of Pb(II), Cu(II) and Zn(II) onto low-cost mineral adsorbent. Journal of Hazardous materials 154, 221-229 (2008).
Sorption of Tc(IV) to geologic materials associated with a geological disposal facility20m
Technetium-99 is one of the most important isotopes likely to be disposed of in the proposed UK Geological Disposal Facility (GDF) for higher-activity radioactive wastes. This is due to its long half life (2.13 x 105 y), fission yield (6%), and its ability to migrate through soils and other environmental components when in its oxidised, pertechnetate, TcO4- form. However, much of the technetium in the GDF is likely to be in the lower oxidation state of Tc(IV) as TcO2(am) or TcO(OH)2(aq). Therefore, an important aspect of the behaviour of technetium in the near- and far-fields of a GDF is its sorption to geologic and cementitious materials in its reduced (Tc(IV)) oxidation state.
Batch sorption experiments on technetium in both oxidised and reduced forms have been conducted in the presence of various materials which are associated with a deep geological disposal facility. These solids can be placed in the following categories:
Clays and clay minerals;
Concretes and cements.
Tc(IV) was produced by electrochemically reducing a solution of Tc-95m, (t1/2 = 60 days,) pertechnetate which was used as a spike added to a carrier solution of reduced Tc-99 pertechnetate solution. Tc(IV) solutions were used at concentrations from 10-9 to 10-11 mol dm-3.
The results for these studies show Rd values ranging from 0 – 39 000 ml g-1 depending on pH and solid material. The results for both oxidised and reduced technetium in the presence of solids associated with a geological disposal facility are presented here. It is noticeable that the Rd is very dependent on the pH. For example, for a 10-9 mol dm-3 technetium solution in contact with bentonite at pH 7, Rd = 21 ml g-1, however, at pH 10 for the same concentration of technetium Rd = 2974 ml g-1.
Surface complexation modelling of the data generated has been performed, as well as characterisation of the solids. In general using bidentate constants give best agreement between model and data, e.g. for bentonite:
Bent-OH + H+ ↔ Bent-OH2+ (Log K = 4.5*)
Bent-OH ↔ Bent-O- + H+ (Log K = -7.9*)
Bent-OH + Na+ ↔ Bent-ONa + H+ (Log K = -0.1)
Bent-OH + TcO2+ + H2O ↔ (Bent-O)2TcO(OH)- + 3H+ (Log K = -0.75)
* Grambow et al. Radiochim. Acta, 94, 627
Effect of Ca<sup>2+</sup> on the sorption of uranium(VI) and humic acid on natural clay20m
In various countries clay is discussed as possible host rock for a nuclear waste repository. The interaction of the clay with actinides, especially U(VI), is the focus of our work. Sorption experiments were performed to estimate the actinide migration in clay formations. Also the influence of humic acid (HA) is investigated. HA are ubiquitously found in natural environments and can interact with e.g. actinides of the nuclear waste. Natural clay contains HA and fulvic acid like organic matter, which can be released from the clay . HA also forms stable colloids. Due to this behavior HA can influence the mobility of actinides, e.g. U(VI), in a nuclear waste repository.
Opalinus clay (OPA) from Mont Terri, Switzerland was studied. Batch sorption experiments were performed in order to determine the sorption ability of U(VI) ([U] = 1x10-6 M) onto OPA in the absence and presence of HA ([HA] = 10 mg/L, 50 mg/L) and of HA in the absence and presence of U(VI) using synthetic OPA pore water (OPAWA, , pH 7.6, I = 0.39 M) and NaClO4 (pH 3-10, I = 0.1 M) as background electrolyte. During these studies a large influence of calcite on the sorption behavior of U(VI) and HA was determined. Calcite presents a fraction of 13% in OPA and its ions occur also in the OPAWA ([Ca2+] = 0.03 M, [CO32-] = 5x10-4 M). In OPAWA, U(VI) forms with the ions in solution the neutral aquatic complex Ca2UO2(CO3)3 . This complex dominates the speciation with a fraction of 99%. In sorption experiments it was shown, that this complex adsorbs weakly onto OPA. Normalized to the specific surface area of OPA (BET = 41.6 m2/g) the U(VI) sorption was determined with 0.05 ± 0.002 µg U/m2 clay. In further sorption studies it was shown that HA has no influence on the U(VI) sorption onto OPA. This was also proved by speciation calculations, which showed that also in the presence of HA the Ca2UO2(CO3)3(aq) complex is the dominating species in solution. In order to interpret the sorption data onto OPA, additional zeta potential measurements were performed, where between pH 0 and 7.5 a negative zeta potential for OPA was determined.
The HA sorption onto OPA in OPAWA was determined with 3.57±0.01 µg HA/m2 (10 mg/L) and 17.28±0.15 µg HA/m2 (50 mg/L). In the presence of U(VI), a slight increase of HA sorption (D = 0.3 µg HA/m2) was observed for [HA] = 50 mg/L. Species calculations showed that Ca2+ ions influence also the HA speciation, because Ca2+ is complexed by HA. Ca2+ is present in such a high concentration, that it saturates the binding sites of HA. Thus, only few binding sites, about 0.1% according to speciation calculations, are available for the complexation of U(VI). Consequently, U(VI) and HA have no effect on each other during the sorption studies. These experiments show the large influence of the calcite fraction of the OPA and thus the resulting composition of the OPAWA on the U(VI) and HA sorption. Thus, calcite should be taken into account for the safety case analysis of a nuclear waste repository.
 F. Claret et al., Sci. Total Environ. 317, 2003, 189.
 F.J. Pearson, PSI Internal Report TM-44-98-07, Switzerland, 1998.
 G. Bernhard et al., Radiochim. Acta 89, 20
(Forschungszentrum Dresden-Rossendorf, Institute of Radiochemistry)
Online <sup>14</sup>C analysis of ultra-small samples with accelerator mass spectrometry (AMS)30m
14C measurements of samples containing 5-50 µg carbon allow dating of archeological artifacts or environmental materials with only traces of organic carbon. Furthermore, fossil and non-fossil sources of carbonaceous aerosols can be apportioned using such measurements (Szidat, 2009). The widely-used preparation of solid targets for 14C measurements, however, often remains the weak point of 14C analysis of ultra-small samples. Even under optimized conditions, reaction yields are small, which results in large isotopic fractionations or even in total loss of unique samples (Szidat et al., 2004). These problems are solved with the implication of a gas ion source (Ruff et al., 2007) at the next generation of small AMS machines: the mini radiocarbon dating system MICADAS is a prototype AMS that achieves the terminal voltage of 195 kV for 14C measurements with a vacuum-insulated high voltage platform in contrast to previous systems based on conventional particle accelerators (Synal et al., 2007). The self-constructed ion source of MICADAS was modified in order to insert CO2 gases directly to the focal point of the sputtering caesium beam (Ruff et al., 2007). A first gas handling system was constructed to supply the gas ion source constantly with CO2 from the sealed ampoules.
In this work, the concept of gas ion sources with its gas handling system will be presented. Furthermore, such ion sources allow on-line coupled systems of separation or combustion of organic compounds with AMS, which also will be elucidated. One example is the coupling of an elemental analyzer (EA), which generates a multifunctional system because it provides automated on-line combustion and 14C measurement of any organic material. Therefore, it can broadly be employed in 14C analysis. Carbon dioxide produced in the elemental analyzer is isolated from other combustion gases with a small external zeolite trap (Ruff et al., 2008). The purified CO2 is transferred from the external trap to the syringe with a low helium flow. This coupling principle can now be adapted to other combustion systems. Different approaches will be discussed.
M. Ruff, L. Wacker, H. W. Gäggeler, M. Suter, H.-A. Synal, S. Szidat, Radiocarbon 49, 307 (2007).
M. Ruff, S. Fahrni, H. W. Gäggeler, I. Hajdas, M. Suter, H.-A. Synal, S. Szidat, L. Wacker, Radiocarbon submitted (2008).
H.-A. Synal, M. Stocker, M. Suter, Nucl. Instrum. Meth. Phys. Res. B 259, 7 (2007).
S. Szidat, T. M. Jenk, H. W. Gäggeler, H.-A. Synal, I. Hajdas, G. Bonani, M. Saurer, Nucl. Instr. Meth. Phys. Res. B 223-224, 829 (2004).
S. Szidat, Chimia 63, 157 (2009).
(University Of Bern)
Radon measurements: a way to disseminate scientific culture among young students in Italy20m
Usually, the lack of information cause to be afraid about what we don’t know, imputing to it a greater hazard. On the contrary we face up without fear activities that have a high level of riskiness, but for which we have direct experience. In other worlds the subjective perception of the risk very often doesn’t correspond to the objective and real risk of an activity. In particular the radioactivity theme is misled because it is almost unknown and the public links this concept to nuclear arms and to its usage in uncorrected way to produce energy in the nuclear power plants, evenif in the last 50 years NPP for civil uses has significantly fewer casualties than any other source of energy. However, because public opinion is driven by emotions rather than rational knowledge based views nuclear power’s association with nuclear weapons has contributed to its lack of acceptance in many places throughout the world and in particular in Italy the “nuclear issue” has been for a long time a taboo. A way to make the public more trusting to nuclear issue, that the people can have a more rationally reactions and could build up a personal understanding about these issues, is to discuss about this theme and about radioactivity and ionizing radiation, starting from young students.
On these bases several Physics Departments with Lauree Scientifiche Project and sections of the National Institute of Nuclear Physics (INFN) with ENVIRAD-SPLASH Project would give to the students of secondary school and to their teachers the opportunity to face these themes with basic information and with an experimental activity.
The approach is to have students engaged in activities that will allow them to understand how natural radioactivity is a part of our everyday environment. This would include how radiation enters our lives in different ways, to demonstrate that natural radioactive sources found in soil, water, and air contribute to our exposure to natural ionizing radiation and how this exposure effects human health.
Depending on local situations and the specific experiences of the students, several approaches were used. However, collaboration among the schools was an essential element in the program’s success. The core idea is that: a) to provide the students a furnished laboratory at their school so that they can measure the natural component of the radioactivity that surround us. In this exercise the measurement of the Rn-222 concentration is particularly well suited b) to show the different types of radiations including ionizing radiations and how they each relate to the other; c) to demonstrate how easily ionizing radiations can be measured; d) and to prove the fun a student can derive from discovery and detection of ionizing radiation in the environment. In this paper the experience of Milano reality is been reported in more detail.
Another objective is to develop a new technique for teaching physics which will enhance scientific interest of students in applications of nuclear physics in both environmental and physical sciences.
(Radiochemistry Laboratory, LASA, Università degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate, Milano, Italy)
Determination of <sup>90</sup>Sr in soil, grass and cereals20m
Environmental samples in Upper Austria have been measured for 90Sr in the year 2005. These measurements were conducted on behalf of the Federal Ministry of Agriculture, Forestry, Environment and Water Management and were part of a project called “Temelin Project”. The aim of this project which started in 1992 is to detect any radiological impact of the nuclear power plant Temelin in the Czech Republic on the environment of Austria. After the nuclear weapon tests the average deposition of 90Sr in Austria amounted to 3.3 kBq/m². In 1986 the average deposition was 0.9 kBq/m². To assess the actual condition in soil, grass and cereals 90Sr was measured in these samples in 2005 and 2006. For all samples oxalate precipitation was conducted and strontium specific columns (Eichrom Industries, Inc.) were used. The calcium concentration in these samples was determined to estimate the amount of resin needed for the preparation. The prepacked 2 ml columns with particle size 100 – 150 µ were used for soil (lower limit of detection (LLD) below 2 Bq/kg). For grass and cereal samples columns were packed with the 100 – 150 µ resin to gain a LLD below 2 Bq/kg and below 0.1 Bq/kg respectively. After digestion of soil samples hydroxide precipitation was used as an additional separation step. The 90Sr was measured by liquid scintillation counting and via 90Y by Cherenkov radiation counting. For quality assurance reasons, first the initial strontium concentration in the sample was determined then a strontium carrier solution was added and after the separation steps the chemical recovery was determined by ICP-MS. Thus, no radioactive spike and just a small amount of the measuring solution were needed. The results are presented and discussed.
(Austrian Agency for Health and Food Safety; CC Radiation Protection and Radiochemistry)
Fossil fuel CO<sub>2</sub> detection by atmospheric <sup>14</sup>C and CO<sub>2</sub> mixing ratio measurements in the city of Debrecen, Hungary20m
Fossil fuel CO2 content in the air of a major Hungarian city (Debrecen) was determined using together measurement of CO2 mixing ratio and radiocarbon (14C) content of air.
In this project we developed a high precision atmospheric CO2 monitoring station in Debrecen. An integrating sampling system (developed by ATOMKI) was applied for radiocarbon measurements. One sampler was installed in Debrecen station and two independent 14CO2 sampling line were installed ~ 300 km far from Debrecen at Hegyhátsál station as independent background references, where high precision atmospheric CO2 mixing ratio measurement is also running since 1997.
During the winter of 2008/09 we measured the mixing ratio and radiocarbon content of atmospheric CO2 at Debrecen and the reference station simultaneously. It was concluded that trends in CO2 mixing ratio variations in time are very similar at the three different sampling points (2 m above ground in Debrecen, 10 m and 115 m above ground in Hegyhátsál). Air quality in Debrecen during September of 2008 seemed to be relatively clear from the point of view of its CO2 content at least. When winter came closer in October, with lover outside temperature and less sunshine hours the CO2 content of air was increased in general at all the three sampling points, but this effect was more intensive closer to the ground level.
According our radiocarbon observations it was clearly indicated that there was not significant amount of fossil fuel CO2 in the air of Debrecen during September in 2008. But during the winter of 2008/09 the 14C value of atmospheric CO2 of Debrecen decreased with more than 40 ‰ relative to September’s results, and according our calculations it was caused by about 20 ppm fossil fuel CO2 which appeared as a surplus amount in the air above the September level.
Speciation and surface complexation modelling of Np(V) sorption on montmorillonite30m
The sorption of Np(V) on Na-montmorillonite (STx-1) has been studied by batch experiments, spectroscopic measurements, and surface complexation modelling with the aim to contribute toward a better understanding of the sorption of 237Np (t1/2 = 2.1 × 106 a) in the near field (bentonite backfill material) and far field (argillaceous rocks) of high-level nuclear waste repositories. Batch experiments were performed in the absence of inorganic carbon and under air-equilibrated conditions with 0.1 and 0.01 M NaClO4 as background electrolyte, 8 × 10-12 and 9 × 10-6 M Np(V), and 3 ≤ pH ≤ 10. At pH > 8 the presence of inorganic carbon has a strong influence on the sorption behavior of Np(V) due to the formation of aqueous Np(V) complexes with carbonate.
Neptunium LIII-edge extended X-ray absorption fine structure (EXAFS) measurements on Np(V)/montmorillonite samples with Np(V) loadings in the range of 0.3-3.5 µmol/g have been performed to determine the speciation of Np at the solid-liquid interface. The EXAFS spectra of samples prepared under ambient air conditions (pCO2 = 10-3.5 atm) revealed the formation of Np(V)-carbonate complexes at the montmorillonite surface.
The results of the batch experiments obtained under CO2-free conditions could be modeled using the two site protolysis non-electrostatic surface complexation and cation exchange (2SPNE SC/CE) model described in . For modeling the sorption behavior of Np(V) on montmorillonite in the air-equilibrated system, the aqueous complexation of Np(V) with carbonate  was included and the following additional surface complexation reaction was required: ≡SOH + NpO2+ + CO32- ⇔ ≡SONpO2CO32- + H+.
 M.H. Bradbury and B. Baeyens, Modelling the sorption of Mn(II), Co(II), Ni(II), Zn(II), Cd(II), Eu(III), Am(III), Sn(IV), Th(IV), Np(V) and U(VI) on montmorillonite: Linear free energy relationships and estimates of surface binding constants for some selected heavy metals and actinides, Geochim. Cosmochim. Acta 69, 875-892, 2005.
 Chemical Thermodynamics of Neptunium and Plutonium, (Eds. J. Fuger et al.) Elsevier, Amsterdam 2001.
(Johannes Gutenberg-Universität Mainz, Institute of Nuclear Chemistry)
The adsorptive behaviour of cadmium on clays20m
Heavy metals present in the environment such as cadmium are considered harmful due to their toxicity. Adsorption-desorption reactions of metals from aqueous solutions to the soil play an important role in influencing the accumulation and transport of metal contaminants. These are affected by the surface and chemical properties of the soil components.
Sorption and desorption of Cd2+ has been examined on a series of clays bentonite, illite, illite-smectite, kaolin and montmorillonite through γ-spectroscopy as a function of pH and ionic strength. Experimental data acquired for the systems studied have been used to determine the isotherms. The order of increasing cadmium adsorption onto the clays in the absence of organic matter has been found to be:
illite<≈ kaolin< montmorillonite< illite-smectite< bentonite
Further, to gain mechanistic insights to the sorption and desorption processes NMR and XRD have been used to probe these systems.
An approach for acquiring data for description of diffusion in performance assessment of radioactive waste repositories20m
Repositories for radioactive wastes are sited in the environment with very low permeability. One of the most important processes leading to the release of radionuclides to the environment is diffusion and therefore data for its evaluation are very important for the results of performance assessment of these repositories. These data are obtained usually from the evaluation of laboratory through-, in- or out-diffusion experiments, which are evaluated by various mathematical methods that have to take into account also deficiencies of real experimental equipments. E.g., a very long experimental time is needed for sorbing radionuclides to achieve stationary conditions under which the standard evaluation of the through-diffusion experiment is applicable. In such cases only values of apparent diffusion coefficients are usually obtainable from evaluation of in- or out- diffusion experiments. A robust performance assessment codes, however, require knowledge of effective diffusion coefficients and equilibrium sorption coefficients, which cannot be easily obtained by the evaluation of in- and/or out- diffusion experiments. This fact can lead to the propagation of uncertainties in performance assessment of radioactive waste repositories. In this paper a new approach is proposed for the evaluation of diffusion data for performance assessment. This approach consist in the following steps: i) experimental measurements of material diffusion parameters (tortuosity, transport porosity) under various conditions (e.g. different density, different ionic strength of water) using non-sorbing radionuclides such as tritium and chlorine for which it is easy to reach conditions under which mathematical solution of diffusion equation is applicable, ii) to measure sorption isotherms for sorbing radionuclides by batch methodology, iii) to calculate diffusion coefficients for sorbing radionuclides from well-defined diffusion coefficients in free water and determined tortuosity, transport porosity and sorption coefficients, iv) to carry out the relatively short in-diffusion experiments with sorbing radionuclides and v) to compare experimental results with simulated curves using the performance assessment computer code. We see the advantage of this approach in the use of the same computer code both for verification of the laboratory diffusion results and for the performance assessment. The uncertainty of description of diffusion in performance assessment is therefore decreased. The relationships between measured data and parameters used in performance assessment are discussed on the basis of batch sorption and diffusion experiments performed for HTO, 36Cl and 137Cs with different types of bentonite.
(Nuclear Research Institute Řez plc)
Poster Apetisers - Nuclear Analytical MethodsRed Hall
(Radio)Chemistry in AMS – a Servant or a Partner?20m
The world demand for ultratrace analyses of radionuclides with long half-lives has been increasing not only in dating, material, environmental, geo-and cosmochemical studies, but also recently in the pharmaceutical and pharmacological applications. The most sensitive tool for such analyses is the dynamically advancing method of Accelerator Mass Spectrometry (AMS) which enables the determination of long-lived radionuclides in concentrations or amounts lower by up to 6 orders of magnitude than by radiometric methods.
AMS is a very powerful but technologically challenging analytical method that is, at present, mainly a domain of physicists. The sample preparation is often carried out by physicists without wider background in chemistry and its procedures or, in a better case, by chemists without practice in the work with radionuclides and/or sufficient knowledge of AMS needs and the collaboration between chemists and physicists in AMS, similarly to some other ultratrace analytical methods seems to be rather insufficient. However, making full use of the sensitivity of AMS is possible only if precise, reproducible, and well defined methods for sample preparation are used.
We suggest that here is the place where radiochemistry, after more than 100 years of its development, can help with its powerful toolbox of micropreparations, carrier and tracing methods, tracking of contamination sources, numerous separation procedures optimised for radiometric determinations and, in some cases, even with chemical suppression of isobars interferences. Full integration of radiochemistry separation and preparation methods into AMS sample preparation could create a synergy resulting in quality samples/methods well suited for high precision AMS measurements at further decreased background and improved sensitivity.
Thus, our contribution is an appeal on a closer collaboration between (radio)chemists and physicists in the field of Accelerator Mass Spectrometry, thus contributing to a better use of its potentials.
(CTU FNSPE, centrum pro radiochemii a radiační chemii)
<sup>129</sup>I in Finnish waters15m
129I is a long-lived beta-emitting (Emax 154,4 keV) radioisotope of iodine. Its half-life is 15,7 million years. 129I is produced mainly by human nuclear activities and especially it has been released to the environment from the spent nuclear fuel reprocessing plants. In the pre-nuclear era 129I/127I ratios in the environment were approximately 10-12. Nowadays 129I/127I ratios have reached values from 10-10 to 10-4.
In this study, activity concentrations of 129I and its distribution into various chemical species (iodide I-, iodate IO3- and bound in organics) were analyzed from four different lakes in Finland and from four different sea locations on the Gulf of Finland, the Bothnian Sea and the Bothnian Bay. 129I was also analyzed from four rainwater samples. Samples were taken in the summer of 2009.
After filtering the 0.3 l water samples, separation of various iodine species was done by anion exchange chromatography: 129IO3- passes through an anion exchange resin bed in NO3- form while 129I- absorbs into the bed. 129I- is eluted from resin with NaClO. Finally samples were precipitated by AgNO3 to form AgI and 129I was measured by accelerator mass spectrometry (AMS). Stable iodine (127I) was analyzed by inductively coupled plasma mass spectrometry (ICP-MS).
First results from a lake in the southern Finland and from water taken from the Finnish Bay in front of Helsinki show that levels of 129I in lake water are around 1×109 atoms per litre while in sea water the levels are 4-5 times higher. 129I occurs both in lake and sea water mainly in iodide form and the fraction of iodate form is only about 5%. The 129I/127I ratio has clearly elevated compared to natural levels, and are approximately the same in sea and in lake, 14×10-8 and 8×10-8, respectively. These results are only preliminary and a better picture of the situation will be obtained after finalizing the project. The results obtained so far are, however, at the same level as obtained in Swedish studies at the same latitudes.
(Laboratory of Radiochemistry, Department of Chemistry, University of Helsinki)
<sup>236</sup>U in well water - a tool for uranium prospection?20m
236U (half-life 23∙Myr) is produced in uranium ore via thermal neutron capture on 235U. The neutrons originate mainly from (α,n) reactions caused by α-particles from the uranium decay series. The equilibrium ratio of 236U/U in natural ore is proportional to the thermal neutron flux, which is expected to be proportional to the uranium concentration in first approximation. Since this fingerprint of high grade ore should stay unaltered in withering and dissolution, it should still be detectable in well water which was in subsurface contact with the ore; thus, such wells should be useful as natural probes for uranium prospection. We expect this signature to be more unambiguous than the uranium concentration in water, recently investigated e.g. in 1. However, measurement capabilities for 236U were developed recently only at very few AMS (Accelerator Mass Spectrometry) facilities, among these at VERA (Vienna Environmental Research Accelerator).
We will discuss the feasibility of uranium prospection by using natural 236U in well water, and summarize existing measurements. Uranium ores show up to 236U/U=10-10, but measurements of uranium from low-concentration rocks or deep well water are sparse or unavailable 2. The connection between uranium concentration and the 236U/U ratio will be discussed, since trace isotopes (serving as (α,n) targets and "neutron poisons") and water content of the rock can alter the 236U production significantly.
A known highest grade ore deposit was located in Jáchymov, Czech Republic. It is mainly depleted now, but is a perfect test case to investigate whether high grade ore is indicated by high 236U/U concentration in well water in the vicinity. Thus, the Jáchymov region could be a perfect test case to study 236U in well water as a tool for uranium prospection.
1. Mehra P., Singh S., Singh K.: Radiation Measurements 42, 441 (2007).
2. Steier P., Bichler M., Fifield L. K., Golser R., Kutschera W., Priller A., Quinto F., Richter S., Srncik M., Terrasi P., Wacker L., Wallner A., Wallner G., Wilcken K. M., Wild E. M.: Nucl. Instr. and Meth. B 266, 2246 (2008).
(VERA Laboratory, Faculty of Physics – Isotope Research, University of Vienna, Währingerstr. 17, A-1090 Vienna, Austria)
Airborne and terrain γ spectrometry monitoring of natural and artificial radioactivity20m
Airborne and terrain gamma-ray spectrometry are very effective methods for radiation control in environment, prospecting of radioactive contamination and localization of radioactive sources. These methods were proved in the system of the military radiation reconnaissance and radiation monitoring of the Czech Armed Forces. The IRIS-XP airborne gamma-ray spectrometer (4x4 liters NaI(Tl) crystals) and terrain gamma-ray spectrometer PGIS-128 (2 liters NaI(Tl) crystal), both produced by PICO Envirotec, Inc. Canada, were used for in-situ experiments. The helicopter Mi-17 was used for airborne measurement and the mobile devices and footpath variant were utilized for measurement on terrain surface. The semi-calibration of described systems was performed by comparison with semiconductor HPGe in-situ gamma-ray spectrometry on selected terrain locality. The spectra of natural radionuclides, such as K-40, Th-232 and U-238, were measured for these purposes. The radiation sources Cs-137 and Co-60 with activity from 100 MBq up to 3 GBq were used for measurement optimization and simulation of radiation events. The terrain gamma-ray spectrometry was also tested under the condition of real contamination in Chernobyl “exclusion zone”.
(NBC Defence Institute Vyškov, University of Defence CZ), DrPetr Sládek
(NBC Defence Institute Vyškov, University of Defence CZ)
Alpha radiometric determination of plutonium and uranium isotopes after separation of the radionuclides by cation exchange and liquid extraction20m
The radioactivity concentration of uranium and plutonium isotopes (Pu-236 and U-232) in water samples has been determined by means of alpha spectroscopy after chemical separation of the radionuclides by cation exchange and liquid-liquid extraction using the Chelex-100 resin and 30%TBP/dodecan. Method calibration using Pu-236/U-232 standard solutions results in a detector efficiency of 19% and in a cation exchange separation efficiency which varies between 60% and 90%, and 50% and 70%, for uranium and plutonium, respectively, depending on the radionuclide concentration in the sample. Application of the method to test solutions of constant radionuclide concentration and variable composition (0.1, 0.5 and 1 M NaCl; 0.1 and 0.5 M Ca(NO3)2; 0.1 and 1 mM FeCl3; 10 and 100 ppm SiO2; 10 and 100 ppm humic acid) shows generally that the cation exchange efficiency is not significantly affected by the presence of major components, except for increased Fe(III) concentrations in solution (> 0.1 mM). The liquid-liquid extraction efficiency is almost similar for both radioelements and varies between 50% and 80%, depending on the radionuclide concentration in the sample. Taking into account that the electrodeposition of the radionuclides under study is quantitative, the total method efficiency is calculated to vary between 30-70% and between 25-55%, for the uranium and plutonium isotopes, respectively. The detection limit of the alpha spectrometric system has been found to be 0.2 mBq/l, suggesting that the method could be successfully applied for the radiometric analysis of uranium and plutonium isotopes in natural waters
(PhD student, Department of Chemistry, University of Cyprus)
Alpha radiometry of uranium by liquid scintillation counting after pre-concentration by cloud point extraction20m
The aim of this study is the radiometric determination of uranium in waters by liquid scintillation counting (LSC) after pre-concentration of the element by cloud point extraction (CPE). For CPE, tributyl phosphate (TBP) is used as the complexing agent and (1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol (Triton X-114) as the surfactant. The measurement is performed after phase separation by mixing of the surfactant phase with the liquid scintillation cocktail. The effect of experimental conditions such as pH, reactant ratio (e.g. V(TBP)/V(Triton), ionic strength (e.g. [NaCl]) and the presence of other chemical species (e.g. Ca2+ and Fe3+ ions as well as humic acid and silica colloids) on CPE has been investigated. According to the experimental results the total method efficiency is (13±2)% and the separation efficiency (60±10)% for the optimum pH and reactant ratio (V(TBP)/V(Triton)=0.1). Regarding the other parameters, generally Ca2+ and Fe3+ ions as well as the presence of colloidal species in solution (even at low concentrations) results in significant decrease of the separation efficiency. On the other hand increasing [NaCl] leads to enhancement of separation efficiency.
The detection limit under optimum experimental conditions has been found to be 0.5 Bq/l indicating that the method could be applied only to waters samples with increased uranium concentration. Moreover, the negative effect of the chemical species found in natural waters limits the applicability of the method with the respect to environmental radioactivity measurements.
(Radioanalytical and Environmental Chemistry Group , Department of Chemistry, University of Cyprus)
Analysis of large and non-standard geometry samples of ancient potteries and bricks by internal monostandard NAA using insitu detection efficiency20m
Studies of archaeological artifacts constitute an important area of research that might provide clues to unravel the past human activities, art, trade etc. Archaeologists are mainly interested in the provenance studies of the artifacts. Archaeological artifacts like potteries, bricks, coins and paintings are mainly studied for their provenance and one of the valid, and accepted methods is through their chemical composition analysis in conjunction with statistical methods. Among the archaeological artifacts, potteries are most widely studied and occasionally bricks are also analyzed. Since they have a strong correlation with the clay/soil source from which they are prepared, elemental concentrations could be used for arriving at correlations. Elements, which are mainly present at trace levels in the artifacts, give authentic clue to their origin compared to the major elements. Elemental concentration ratios of Al and Sc, due to their non–volatile nature and La and Ce, due to their similar geochemical properties are used for preliminary grouping. The confirmation of grouping is done from statistical analysis like principal component analysis (PCA) and cluster analysis (CA). The present paper describes application of large sample instrumental neutron activation analysis (LS-INAA) method for provenance study of potteries and bricks using scandium as internal monostandard.
In the present study, samples of ancient potteries and bricks belonging to 4th-5th century BC to 4th century AD were excavated from 15 different Buddhist sites in Andhra Pradesh, India. Samples in the larger mass range of 10-50 g were taken for the experiment, irrespective of their geometry. Samples were irradiated for 7 hours in Apsara reactor, BARC. Radioactivity assay was carried out using a 40% relative efficiency HPGe detector coupled to 8k MCA. Peak areas were determined using peak-fit software PHAST. The k0-based internal monostandard INAA (IM-INAA) was used for arriving at the elemental concentration ratios with respect to Sc. Since the method uses insitu detection efficiency, it is geometry independent and non-standard geometry samples could be analyzed. Concentrations of about 18 elements such as Na, K, Sc, Cr, Fe, Co, Ga, As, Br, La, Ce, Nd, Sm, Yb, Hf and Th were determined in both potteries and bricks. The results of elemental concentration ratios with respect to Sc show that the both potteries and bricks fall into four major groups. It was observed that in some samples of potteries and bricks, collected from same location, correlations exist indicating the source of clay/soil may be the same. We would like to highlight that the provenance / grouping study of archaeological samples could reliably be carried out through their elemental concentration ratios than the absolute concentration values and thus the present method is a suitable one for this study.
Authors from GITAM University acknowledge UGC-DAE Council of Scientific Research, Mumbai for the financial assistance. This work is also a part of the IAEA Coordinated Research Project (CRP Code : F2.30.27).
(GITAM Institute of Science, GITAM University, Visakhapatnam – 530 045, India)
Applicability of k<sub>0</sub>-based neutron activation analysis using a Compton suppression γ-ray spectrometer20m
Compton suppression system (CSS) in conjunction with γ-ray spectrometer allows to lower the detection limits for certain elements by reducing the background levels in the acquired γ-ray spectra. The calibration of CSS for use in the k0-based neutron activation analysis (k0-NAA) has been performed in normal mode and applied to Compton suppression mode. In this case, efficiency data are only applied to radionuclides that emit non-coincident γ-rays. In this work the applicability of the k0-NAA method using CSS (k0-CSNAA) in Compton suppression mode for radionuclides that emit coincident γ-rays is tested. The SMELS (a synthetic multi-element standard) consisting of nuclides with different γ-ray energy and Q0 values was used to evaluate the Compton suppression factor for several radionuclides of interest, e.g. 60Co, 51Cr, 152Eu, 59Fe, 75Se, 46Sc and 85Sr. The applicability of k0-CSNAA has been tested by analyzing several reference materials, i.e. Coal Fly Ash (NIST-SRM-1633a), Soil (IAEA-Soil-7) and Lichen Material (IAEA-CRM-336). Preliminary results of the test are presented and discussed.
DrDung Manh Ho
(Technological and Nuclear Institute, Sacavem, Portugal)
Application of Monte Carlo simulation to design a modular <sup>241</sup>Am-Be neutron irradiator irradiator20m
Neutron irradiator facilities with 241Am-Be sources are worldwide available in order to perform neutron activation analysis (NAA), to investigate materials in different research areas or to test and calibrate neutron detectors and environmental or personal dosemeters. The use of a neutron irradiator is advantageous because have a very stable neutron flux, even it is many orders of magnitude lower than the one of a nuclear reactor or a particle accelerator. Many of irradiators are realized with neutron sources located at fixed positions and accordingly the characteristics of neutron spectrum previously assessed do not change. However, an interesting chance is to have a modular facility, capable of varying conditions of irradiation and setting the prevalence of fast or thermal neutron spectrum component.
In this work we report the Monte Carlo studies devoted to design a modular 241Am-Be neutron irradiator making use of different moderators (water, graphite, polyethylene and so on) in order to obtain a neutron energy distribution useful to test neutron detectors or personal dosemeters.
The optimization of thicknesses and shape of the moderators and shielding materials was obtained with a Monte Carlo simulation with MCNP5 code. An experimental test to verify the reliability of the simulation by means of NAA of selected materials was also performed. Once realized, the designed neutron irradiator will provide an useful facility for radiochemical material studying and testing and calibration of personal dosemeters or neutron measurement equipments.
(University of Palermo - Nuclear Engineering Department)
Applications of nuclear analytical methods in the historical glass in Thailand20m
Cultural heritage objects are highly heterogeneous. Due to the complex nature of materials and objects, their analysis needs to use extremely sensitive, spatialy resolved, multi-elemental and versatile methods that should be as a non invasive as possible and give complementary information at different scales; from the macroscopic to the namometer scales. In this work, XRF, SEM-EDS, PIXE, EPMA and XAS were used to characterize the chemical composition and microstructure of the historical glass in Thailand such as ancient glass beads, ancient decorative glasses and old-styled gold mosaic glass. It can be concluded that these are powerful tools for investigation of heterogeneous glassy materials.
Assessment of contamination levels and dispersion in a mining impacted area by INAA and μ-PIXE analysis20m
Assessment of contamination levels and dispersion in a mining impacted area by INAA and Micro-PIXE analysis
H. M. Anawar, M. C. Freitas, H. M. Dung
Instituto Tecnológico e Nuclear Reactor, Apartado 21, E.N. 10, 2686-953, Sacavém, Portugal,
Past mining activities, random disposal without poorly precautionary and rehabilitation measures, erosion, leaching, and atmospheric dispersal of mine soils, tailings and waste may contaminate the surrounding environment and nearby locality with highly toxic trace elements, and natural radionuclides in the vicinity of Sao Domingos mine, Portugal, a copper-sulphide open pit mine. Toxic trace elements, rare earth elements and natural radionuclide were measured in mining soils, plants, lichen and moss samples by using instrumental neutron activation analysis (INAA) and µ-PIXE. This study has carried out the assessment of magnitude of contamination levels and dispersion of above contaminants in and around the mining area. The levels of the elements were very high in all types of samples including the soils, lichens, moss and plant: the highest levels were recorded in the samples collected close to ore processing sites and diluted with distance. The concentrations of As, Sb and other elements in the soils, plant, lichen and moss samples were much higher than the regional background levels reflecting the high magnitude of contamination in and around the mining area and the possible health risk for the inhabitants living nearby the mining affected area. Patterns of bioaccumulation of elements throughout the study area were quite similar for widespread pollutants such as As, Sb, Cu, Zn, Fe, Br, Co, La, and Cr. The lichen, moss and plant samples are important biomonitors of terrestrial and atmospheric pollution in mining affected areas. Some of the plant species with high biomass and extensive root systems, grown abundantly and spontaneously in the area, are suggested as the suitable candidate for the phytoremediation of the mining contaminated soils.
Calibration and Environmental Monitoring Using PGIS-128 Gamma-ray Spectrometer20m
The portable PGIS-128 gamma-ray spectrometer, produced by Pico Envirotec, Inc., Canada, was originally designed for the geological purposes and the determination of K, U and Th concentrations in soil and rocks. The device is fully calibrated for K, U and Th. However, its functions have been extended, and now the gamma-ray spectrometer is available with the dose rate function (in nGy/h) and the Cs-137 window (in cps) measured in real time. Due to one-second sampling and real-time processing, now PGIS-128 can be used for fast and precise environmental monitoring at relatively large environmental areas with on-line mapping on the HHC display and/or the post-mapping. To calibrate the PGIS gamma-ray spectrometer and to convert the count rates (cps) in the Cs-137 window to the surface activity of Cs-137 (in kBq/m2), the Beck’s method or the standard stripping method can be used. This contribution is focused on the Beck’s method. Some results and the measurement conditions are also presented.
(EnviMO Brno Czech Republic)
Characterization of abandoned contaminated Valongo mining area at Portugal, by INAA20m
At Sao Domingos mining (southern Portugal near Spanish border), we have collected soils and vascular plants growing there 1-3. The values we found for arsenic in soils were between 400 and 3600 mg/kg. All the plants we could find growing there were: Agrostis castellana Boiss. & Reuter; Corrigiola litoralis L.; Erica andevalensis Cabezudo & Rivera; Erica australis L.; Eucalyptus camaldulensis Dehnh.; Genista polyanthos R. Roem. ex Willk.; Juncus acutus L.; Nerium oleander L.; Nicotiana glauca R.C. Graham; Piptatherum miliaceum (L.) Coss.; Rumex scutatus L. subsp. Induratus. The maximum values we have found for arsenic transfer from soil to these vascular plants was 0.3%, which is not sufficient to bioremediation purposes, i.e., seeding one of the plants in the arsenic contaminated area would not results in a large amount of arsenic removed from the soil. Therefore, we went to other mine (Valongo mine, northern Portugal, near Oporto) and we collected again soil and vascular plants which existed there. Soil results pointed out arsenic values up to 0.6%. The vascular plants which we found there are: Agrostis curtisii Kerguélen; Agrostis fouilladei P. Fourn.; Amanita caesarea Scop.; Digitalis purpurea L.; Erica australis L. subsp. aragonensis (Willk.) Cout.; Erica cinerea L.; Juncus conglomeratus L.; Pteridium aquilinum (L.) Kuhn; Pterospartum tridentatum (L.) Willk. subsp. cantabricum (Spach) Talavera & P.E.; Ulex minor Roth. We also collected some moss samples and water from the wells and small river of the area, to compare with previous water sampling at Sao Domingos mine, where we found arsenic values between 0.006 and 1.78 mg/L. The aim of this work it to determine arsenic (and other chemical elements) in the mosses and vascular plants collected at Valongo mine, by neutron activation analysis, in order to determine the transfer coefficients between soil and mosses or vascular plants and eventually find the suitable biorremediator for Sao Domingos mine.
1. Freitas M. C., Pacheco A. M. G., Anawar H. M., Dionísio I., Dung H. M., Canha N., Bettencourt A., Henriques F., Pinto-Gomes C. J., Capelo S.: J. Radioanal. Nucl. Chem. 282, 21 (2009).
2. Anawar H. M., Freitas M. C., N. Canha N.: 5th International Workshop on Biomonitoring of Air Pollution (BioMAP-5). Buenos Aires, Argentina, 20-24 September 2009.
3. Landsberger S., Robinson S., Freitas M. C., Canha N., Pacheco A. M. G., Anawar H. M.: 5th International Workshop on Biomonitoring of Air Pollution (BioMAP-5). Buenos Aires, Argentina, 20-24 September 2009.
(Instituto Tecnológico e Nuclear)
Chemical composition of silica phytoliths. Comparison of different isolation methods.20m
The silica phytoliths, also called biogenic opals, are formed in many plant species. It has been found that information on their chemical composition is limited, except for several major elements. Comparison of different methods for isolation of silica phytoliths from plant material was performed in this work. Dry ashing and acid digestion were used and their influence on chemical composition of the prepared samples was studied. Barley (Hordeum vulgare L.) was used as a model plant and the phytoliths were extracted from different parts of the plant body -- stems, leaves, awns. The analysis of the elemental composition was performed by instrumental neutron activation analysis in both short and long term irradiation modes which allowed determination of more than 30 major and trace elements.
(Nuclear Physics Institute, Academy of Science of the Czech Republic)
Comparative kinetic studies on the corrosion process using two methods based on the β-rays retention and atomic absorption spectroscopy20m
The paper deals with the corrosion kinetics of some steels using two different methods of investigation. The first one is a radiochemical method based on the retention of β-rays emitted by a 204Tl source, by the iron ions transferred into the solution by anodic dissolution of metal samples. The second one is based on the atomic absorption spectroscopy, follows the increase in time of the concentration of the same iron ions in the given aggressive medium. Nitric acid of different concentrations was used as corrosive medium. The obtained experimental data result in two different rate constants that can quantitatively characterize the corrosion process for each given reactant system by the proposed methods. The values obtained by these two methods of investigation are generally in keeping, however more precise will be those obtained through atomic absorption spectroscopy due to its higher precision in the determination of the concentration of the iron ions transferred into the corrosive solutions. However, the proposed radiochemical method seems easier and faster.
("Al.I. Cuza" University, Faculty of Chemistry)
Composition analysis of zirconium alloys by k<sub>0</sub>-based PGAA using Budapest cold neutron beam facility20m
Zirconium and its alloys are important materials in nuclear power technology. Zirconium alloys namely zircaloy 2, zircaloy 4 and Zr-Nb alloy are mostly used for fuel cladding and pressure tubes in water-cooled nuclear power reactors due to their low neutron absorption cross section, high corrosion resistance and good thermal conductivity. For nuclear quality control, it is important to analyze these alloys to ensure their conformity to specifications. Analytical methods, which are non-destructive in nature, bulk sample analysis capability with negligible matrix effect, are preferred for the analysis of such materials. Neutron induced prompt gamma-ray activation analysis (PGAA) is one of the suitable methods. In the present work, PGAA was used for the composition analysis of three types of zircaloys namely zircaloy 2, zircaloy 4 and Zr-2.5%Nb alloy. All the measurements were performed at the PGAA facility of the Budapest Research Reactor using cold-neutron beam. The thermal equivalent neutron flux at this position is 1.2×10^8 cm-2 s-1. Samples in the mass range of 0.3-0.5 g, kept inside thin Teflon bag, were irradiated in vacuum and the prompt γ-rays were measured for 3-10 h with a HPGe detector (sample-to-detector distance 23 cm) surrounded by a Compton-suppressor and passive shielding. The absolute counting efficiency of the detector was determined using 133Ba and 152Eu and prompt gamma rays from 14N(n,γ)15N and 37Cl(n,γ)38Cl. The γ –ray spectra were complex due to presence of multi-γ producing elements/isotopes and they were analyzed for peak areas by Hypermet PC (MS DOS Version 5.01). The minor elements detected in three different zircaloys, in addition to major Zr, are: Sn, Fe, Cr and Ni in zircaloy 2, Sn, Fe and Cr in zircaloy 4, and Nb, Fe and Cr in Zr-2.5% Nb alloy. The trace elements detected in general are B, Hf, Ti, Mn and Co. Trace amounts of Cl were also detected in zircaloy 2 and 4. Since all the major and minor elements were amenable to PGAA, the absolute concentrations of all the elements were determined using mass balance procedure i.e., without using concentration of any external or internal standard. The advantages of the method are: (i) it is non-destructive, (ii) it could detect trace amounts of important elements like B, Hf and Cl in the presence of major/minor elements, and (iii) all elements determined except for B have multiple γ-rays, which help in self-validation of methodology.
This work was carried out under INSA-HAS international exchange program (No. IA/Misc. 2009-2010/4237) and the financial assistance by INSA and BARC (India) and HAS (Hungary) is duly acknowledged. Authors from BARC acknowledge Institute of Isotopes, Budapest for providing PGAA facility.
1.R. Acharya, A.G.C. Nair, A.V.R. Reddy, A. Goswami, J. Nucl. Mat., 326 (2004) 80.
2.C. Yonezawa, Anal. Sci., 9 (1993) 185.
3.Zs. Revay, Anal. Chem., 81 (2009) 6851.
(Department of Nuclear Research, Institute of Isotopes, H-1525 Budapest, Hungary)
Determination of <sup>210</sup>Po and uranium in high salinity water samples20m
Among of the naturally occurring radionuclides in the different types of water the long lived uranium isotope 238U, two radium isotopes: 228Ra, 226Ra, and 210Po are of practical importance due to their radiotoxicity. The observed levels of these radionuclides in underground water depend on the chemical compositions of the adjacent geological formation. Under favourable conditions, for example in the presence of chloride and bicarbonate anions, solubility of mineral rock components including trace amounts of radionuclides increases. A role of the underground water supplying systems including geothermal water is recently rapidly growing as they are used not only for energetic, balneological or recreational purposes but as well as a source of drinking water that should be in accordance with EU Directive 98/83/EC and WHO recommendation.
The aim of these study was to elaborate a fast and efficient method for simultaneous determination of uranium and 210Po in high salinity water samples.
210Po and uranium radionuclides were preconcentrated from 0.5 dm3 saline media by co-precipitation with hydrated MnO2, followed by dissolution of the precipitate in 200 ml of 1 M HCl. Uranium radionuclides can be directly determined by ICP MS method, using part of this solution because the total salinity decreases below 1 g/dm3. From the second part of solution, before 210Po separation for liquid scintillation counting, majority of naturally occurring α-emitting radionuclides (uranium, thorium and protactinium) are stripped by extraction with 50 % solution of HDEHP in toluene. Finally 210Po is simply separated from other interfering nuclides by direct transfer to an extractive scintillator containing 5 % of trioctylphosphine oxide (TOPO) in Ultima Gold F cocktail and determined by a α/β separation liquid scintillation technique. The detection limits are <1 mBq/dm3 for 210Po and 0.01 ppb for 238U.
Quality assurance of the worked out method was checked out in two ways:
1) participation in the IAEA interlaboratory studies (see Table 1) for 210Po determination in water samples
2) determination of uranium and 210Po in Standard Reference Material IAEA-381 – Irish Sea water. Uranium recovery for these samples was in the range 0.88±0.05. 210Po activity is not reported for this SRM, therefore its activity determined by elaborated method was compared with that obtained by direct 210Po deposition on silver discs and α spectrometry counting. These two methods gave practically the same value 30.5±2.3 mBq/dm3 and 30.0±3.0 mBq/dm3, respectively.
Table 1 Results (in Bq/kg) of interlaboratory studies 210Po in acidified water
Sample IAEA value IAEA unc. Measured value Measured unc. Measured/IAEA
1 52.8 1.4 52.0 0.6 0.99
2 101.6 2.8 95.3 1 0.94
3 52.8 1.4 52.1 0.7 0.99
4 101.6 2.8 99.3 1 0.98
5 blank - 0.3 0.03 -
(Technical University of Lodz, Faculty of Chemistry)
Determination of <sup>238,239,240,241</sup>Pu, <sup>241</sup>Am, <sup>242,243,244</sup>Cm, <sup>90</sup>Sr, <sup>55</sup>Fe and <sup>63</sup>Ni in low and intermediate level operational radwaste20m
Radioanalytical method for the determination of radionuclides so called “difficult to determine” has been developed to characterize liquid and solid operational low and intermediate level radioactive waste. The main steps of the method involve digestion of sample of various matrixes, primary separation of radionuclides from matrix with the aim to reduce high γ activities and final purification of radionuclides using extraction chromatography. The commercially available Eichrom resins (UTEVA, TEVA, TRU, Sr Resin and Ni Resin) have been applied. The method enables the simultaneous determination of 238Pu, 239,240Pu, 241Pu, 241Am, 242Cm, 243,244Cm, 90Sr, 55Fe and 63Ni from a single sample. Radionuclides were measured by means of α spectrometry and liquid scintillation. After measurements of 238Pu and 239,240Pu, plutonium isotopes were removed from the stain steel disc and following additional purification 241Pu was measured using liquid scintillation. The method was applied for determination of radionuclides in samples of different matrixes derived from Ignalina NPP e.g. reactor water, spent fuel pool water, evaporated concentrate, spent resins, dust, graphite etc. Accuracy and precision of Pu, Am and Cm analysis were tested in intercomparison runs organized by the Risø National Laboratory, Denmark and in proficiency test organized by National Physical Laboratory, UK.
The authors would like to acknowledge the financial support of European Commission (European Atomic Energy Community [EURATOM]) for funding project 211333 in the Seventh Framework programme.
The work has also been supported by Agency for International Science and Technology Development Programmes in Lithuania (contract No. 31V-180).
(Institute of Physics)
Determination of <sup>90</sup>Sr and <sup>210</sup>Pb in deer bone samples by liquid scintillation counting after ionic exchange procedures20m
Environmental monitoring of hazardous radionuclides is an important issue. 90Sr can be found in the environment due to the global fallout from atmospheric nuclear explosions and the Chernobyl accident in 1986. It is one of the most hazardous fission products due to its chemical similarity with calcium, because it can be accumulated in bone tissue delivering irradiation doses to the bone marrow.
210Pb is a naturally occurring radionuclide which also accumulates in bones. If these two nuclides are measured, a natural and an anthropogenic activity concentration can be compared for the respective samples. Deer bone samples were selected as a feasible environmental contamination indicator.
This work describes different procedures for the isolation of 90Sr and 210Pb from deer bones by anion exchange methods and their sequential measurement. The aim was to obtain pure 90Sr and 210Pb spectra in order to avoid spectrum deconvolution procedures.
To prevent collection of Pb on the Sr•Spec® resin we first separated Pb on a Dowex anion exchange column. Sr, which is not held back on the Dowex column, was then purified using Sr•Spec® resin: first Ca and the Ra isotopes were eluted with 3M HNO3 and then Sr was eluted with distilled water. With this two-step procedure of lead separation on Dowex followed by Sr purification on Sr•Spec®, pure 210Pb and 90Sr spectra can be achieved by liquid scintillation counting of the respective eluting solutions. The chemical yield of both steps was determined by ICP-MS. Our results of re-measured samples show satisfying agreement with data obtained by a modified Sr•Spec® method and also by the “classical” 90Sr determination using fuming nitric acid.
(Institute of Inorganic Chemistry, University of Vienna)
Determination of magnesium in biological materials by neutron activation and anti-coincidence γ-ray spectrometry20m
Magnesium is considered as an essential element at moderate levels. Both deficiency and toxic effects of Mg in humans have been reported in the literature. Titrimetry, spectrophotometry, and atomic absorption spectrometry are generally used for the measurement of Mg levels. Instrumental NAA (INAA) is also an attractive tool for the rapid, simple and reliable determination of Mg. However, due to high background activity in biological samples, the measurement of gamma-rays emitted by 27Mg is generally difficult. The main objective of the present work has been to study the advantages of anti-coincidence gamma-ray spectrometry for the determination of low levels of Mg in biological materials using INAA. The 27Mg nuclide has a half-life of 9.46 min and it emits two major gamma-rays, namely 843.8 and 1014.4 keV, which are not coincident. Therefore, the use of anti-coincidence counting should not cause any reduction in peak efficiency of either of the photopeaks. The peak efficiency reduction factors of the two peaks have been measured as 0.98 and 1.00, respectively. It has been observed in many biological materials that the background around the 1014.4-keV peak of 27Mg is mainly due to the 1778.9-keV peak of 28Al, 1368.6-keV peak of 24Na, 1642.7-keV peak of 38Cl, and 1810.7-keV peak of 56Mn. Anti-coincidence counting technique can be beneficially used under such situations. Several biological reference materials (RM) and standard reference materials (SRM) were analyzed for Mg by INAA. Between 200 and 700 mg of these materials were irradiated in the Dalhousie University SLOWPOKE-2 Reactor facility at a neutron flux of 5 × 1011 cm-2 s-1 for 1 min, allowed to decay for 1 min, and counted for 10 min. The anti-coincidence gamma-ray spectrometer used in this work consisted of a HPGe detector and a 10"x10" NaI(Tl) guard detector with a 3"x3" NaI(Tl) plug. The peak-to-Compton plateau ratio of this system is about 590:1. The 843.8-keV peak suffers from interference by the 846.8-keV peak of 56Mn which has a longer half-life of 2.58 h. In the anti-coincidence counting mode, the percentage overlap of the 843.8-keV peak is less because of the suppression of the 846.8-keV peak. We have developed a simple correction method which has been used for the determination of Mg in 15 NIST RM and SRM using the 843.8-keV gamma-ray of 27Mg. The measured values have been found to agree well with the certified values.
Determination of radiostrontium in food and water samples using fuming nitric acid20m
The objective of this work was the determination of radiostrontium content in selected food and tap water samples collected within environmental monitoring programme of Federation of Bosnia and Herzegovina. It included food samples of vegetables, fruit, meat, cereal, milk and milk products. The radiostrontium content in environmental samples was determined by the fuming nitric acid method. This classic way of analyzing radiostrontium makes use of the low solubility of Sr(NO3)2 in fuming nitric acid solutions. The procedure included successive precipitation of 89/90Sr as nitrate several times to achieve a good separation from most elements, especially Ca. Chromate precipitations were performed to eliminate Ba, Ra and Pb, followed by hydroxide precipitations to eliminate traces of Y. Counting sources were prepared by weighing SrCO3 on a planchette and measured on a low background proportional gas flow β counter. The Sr yield was determined using Sr carrier and it varied between 60-90%. Quality control was ensured through analysis of reference materials, blank determination and background determination. Activity concentration of radiostrontium varied between 0.012 Bq/kg and 0.428 Bq/kg for vegetables samples, 0.007 Bq/kg and 0.257 Bq/kg for fruit samples, 0.0995 Bq/kg and 0.289 Bq/kg for cereal samples, 0.024 Bq/L and 0.113 Bq/L for milk and milk products, below MDA (0.004 Bq/kg) for meat samples and for tap water samples between 0.878 Bq/kg and 3.78 Bq/m3.
Determination of selenium in soft and durum wheat (plant and grain) using the short-lived nuclide20m
The increasing attention paid to the role of selenium (Se) and selenoproteins in human health stems from an equally growing body of evidence on their actual (general) importance for a healthy immune system, and on their protective (specific) effects against cardiovascular disease, asthma, male sterility, and, especially, certain forms of cancer. The current Recommended Dietary Allowance (RDA) for adult men and women (> 14 y) is 55 μg of the element per day. The Portuguese situation is hard to assess due to scarce information and lack of consistent studies on this subject, though unlikely to differ much from Europe at large, where falls in Se intake - and corresponding drops in blood indicators of Se status - have raised a widespread concern. In these terms, an extensive investigation of Se levels in cereals and their cultivation soils is being carried out across the main production areas of mainland Portugal, with a view to an eventual Se-biofortification of major cultivars (under research contract PTDC/QUI/65618/2006; FCT-MCTES, Portugal). Total Se is assessed by instrumental neutron activation analysis (INAA), through short irradiations on the fast pneumatic system (SIPRA) of the Portuguese Research Reactor (RPI-ITN), with an acquisition system by ORTEC - a DSPEC Pro digital γ-ray spectrometer and a liquid-nitrogen-cooled, high-purity-germanium detector (HPGe), connected to a 4096 multi-channel analyser. The short-lived nuclide 77mSe, that features a half-life time of 17.5 s, is used to determine the Se content in SIPRA. Full optimisation of the procedure for Se determination is still ongoing. Still, several tests on the SIPRA with the reference materials NIST-SRM 1567a (Wheat Flour) and NIST-SRM 1568a (Rice Flour) have been yielding results that are quite satisfactory already. Reference samples have been put through cyclic neutron activation analysis (CNAA), at a flux of 2.6x1016 neutrons per square meter and second. The number of cycles for each sample was 15, with both irradiation and counting times of 20 s, and a decay time of 5 s. Three replicate samples of 80-110 mg (in polyethylene capsules) have been used for each reference material; concentrations were determined by the relative method. This paper is focused on wheat samples - soft (bread) and durum wheat; Triticum aestivum L. and Triticum durum L., respectively - from the 2009 campaign, and discusses the Se distribution in grains and other parts of wheat plants (roots, leaves), toward an eventual supplementation of the element in different growth stages. A few other experiments with the Chinese soil standards GBW07404 (NRCCRM Soil NCS DC 73322) and GBW07406 (NRCCRM Soil NCS DC 73324), as well as with rye roots and soils from rye fields, were not that conclusive due to a very high activity of the samples. Such tests will be repeated with the DSPEC Pro in lieu of the DSPEC jr, since the latter does not properly account for counting losses.
(CERENA-IST, Technical University of Lisbon)
Determination of silver and gold in copper concentrate20m
Many copper ores contain significant quantities of silver and gold. Copper concentrate, the intermediate in the ore processing, is an important source for production of gold and silver. Methods for determination of noble metals have been reviewed by Beamish and Van Loon . The most common method for determination of noble metals in geological sample is atomic absorption spectrometry with a fire-assay pre-concentration step. One of the most sensitive method for analysis of noble elements is neutron activation analysis . Instrumental neutron activation has been applied to determine of noble elements in ores, but generally it is required to separate noble elements from interfering and matrix activity. Several radiochemical schemes have been reported to isolate one or more of the noble metals during analysis. These schemes include solvent extraction, distillation, ion-exchange, precipitation and others.
Simultaneous determination of silver and gold in copper concentrate sample was carried out by neutron activation analysis method. Initially, copper concentrate sample was analysed by ED-XRF to obtain qualitative information and found that copper and iron were present in major proportions. Instrumental neutron activation analysis (INNA) was followed by radiochemical or chemical neutron activation analysis. During INAA, cooling time of about a week is required before 198Au could be measured because of high activity due to 64Cu and 24Na whereas 110mAg was measured after further cooling of a week. To reduce the analysis time, radiochemical neutron activation analysis and chemical neutron activation analysis were carried out. The noble elements form anionic complex with moderate molarity of HCl that are readily retained on anion exchanger. The distribution coefficient values for gold and silver are very high at lower HCl normality whereas copper and iron have negligible values. Sodium is not retained. Hence, ion exchange separation and pre-concentration of gold and silver were carried out from 1N HCl solution. The value of gold by INAA agreed well with the values obtained by RNAA and CNAA. However, the value for silver was significantly lower in case of RNAA and CNAA method compared to INAA. This may be due to loss of silver as silver chloride. The separation procedure was modified to avoid loss of silver during separation.
1. F. E. Beamish and J. C. Van Loon, “Recent advances in the analytical chemistry of the Noble metals”, Pergamon Press, Oxford, 1972.
2. Sanjiv Kumar, Rakesh Verma and S. Gangadharan, Analyst, 118 (1993) 1085.
DrKallola Kumar Swain
(BHABHA ATOMIC RESEARCH CENTRE, MUMBAI, INDIA)
Determination of the impurities of reactor core graphite with neutron activation analysis, X-ray fluorescence and mass spectrometry techniques for graphite waste modeling20m
In nuclear energetics is very important to handle radioactive waste properly. After closing nuclear facility significant amounts of radioactive waste will occur, which disposal will depend on their activity. The main source of radioactivity in the NPP’s equipment are the neutron activation products. Their amounts depend on the elemental composition of materials used for building a nuclear facility. In the cores of channel and gas cooled reactors huge amounts of high purity graphite is used as a moderator. Because being in an intensive neutron flux for a long irradiation period minor graphite impurities such as Cs, Sr, Eu, U, Cd, U, Th play the major role in the formation of medium and long-lived radioactive nuclides. As graphite is difficult to dissolve, advanced measurement techniques must be used. In this work measurement methods of neutron activation analysis, X-ray fluorescence and mass spectrometry for the evaluation of minor graphite impurities will be presented and their results critically compared. We show a good agreement between results of an expensive neutron activation analysis and rapid mass spectrometric measurements. We have found that minor graphite impurities of interest are in 10 ppm – 10 ppt concentrations range. These results will be used for the Ignalina NPP graphite decommissioning.
(Institute of Physics, Savanoriu ave. 231, Vilnius LT-02300, Lithuania)
Development of k<sub>0</sub>-cyclic neutron activation analysis at the Portuguese research reactor20m
The fast pneumatic transfer system (SIPRA) for short irradiations at the Portuguese research reactor has been upgraded with a new spectrometer incorporating Zero-DeadTime corrections and new software for use alongside a modern computer. The development of cyclic NAA based on the k0 methodology for SIPRA has been performed. To ensure the accuracy of the system for very short lived nuclides (e.g. 77mSe and 20F), the calibration of transit time with millisecond timing resolution was performed. The results of k0-cyclic NAA for standard reference materials have been shown with a particular focus on selenium.
(Reactor-ITN, Technological and Nuclear Institute, E.N. 10, 2686-953 Sacavem, Portugal)
Development of the method for determination of technetium in environmental and biological samples20m
Technetium is a one of product of nuclear fission of uranium and therefore could be found in a trace concentration in the Earth’s crust. It was estimated that a kilogram of uranium contains 1 nanogram (10−9 g) of technetium . However, besides of naturally occurred Tc, in the last several decades its relatively high amount was artificially produced in the nuclear reactors by the thermal neutron fission of 235U and 239Pu reactor fuels with the fission yield product of 99Tc of about 6.1% . The 99Tc has a half-life of 2.13*105 a, giving a specific activity of 650 MBq g-1 and decays by emission of beta-1 with Emax 300 keV. It has been released into the environment as the results of nuclear weapons testing and low- and intermediate-level waste disposal, and will be an important component of high level wastes when these are finally disposed . Geochemically, Tc exists in two stable oxidation states depending on the redox conditions; it forms reduced species, predominantly Tc4+ and its complexes and compounds, however could also occurs as Tc (VII), which forms the pertechnetate anion, [TcO4-]. The environmental redox chemistry of technetium is thus very important in governing its mobility.
As a beta-emitter the 99Tc are determined with conventionally used low-level beta-counters. However, due to the often complicity of the analyzed samples (e.g. high concentrated salt samples) a separation procedure prior to the counting should be applied. In such case an internal standard should be applied in order to find out a chemical yield of the overall analyzing method. For the determination of recovery of 99Tc the short-lived isotope 99mTc (half-life: 6 hours) is usually applied that is sometimes unacceptable due to the rare availability, relatively high specific activity and low half-time and costs of metastable 99mTc.
In the present study we propose a new methodology for the assessment of the overall recovery of 99Tc determination by combining of the conventional beta-counting method with relatively fast inductively coupled plasma mass spectrometry (ICP-MS) measurements. The principle of the developed method is to use the naturally occurred Rhenium (as a homolog element to Technetium) as an internal standard in order to find out the losses of the analyte during of sample preparation procedure. The determination of Rhenium was performed by ICP-MS method and its recovery values were used for the correction of results for 99Tc measurements. The accuracies of Tc and Re recoveries observed by application of such approach were found to be in the range of 95-105%. After the recovery studies the developed procedure was applied for analysis of Tc activity in available standard solutions as well as in real samples: environmental (high concentrated salt samples) and biological (urine) samples. The results showed a good agreement of measured Technetium content with the predictable values and will be discussed during the presentation in details.
(Reserch Center Jülich)
Gross α activity determination in water and <sup>210</sup>Po20m
The gross alpha activity is defined as the total activity of the alpha emitters. Gross alpha and beta activity screening methods have been developed to determine if radionuclides specific analysis is required to further characterize the water. There may be a loss of radionuclides during storage of water sample caused by the adsorption onto the container wall and by the precipitation and coprecipitation. It is generally recognized, however, that these effects can be minimized by acidification of the samples after collection utilizing HNO3 or HCl.
Polonium 210 is an alpha emitter, a member of the uranium decay series. This radionuclide originates by radioactive decay of 222Rn. In water with elevated amount of 222Rn, the presence of 210Po can contribute significantly to the measured value of the gross alpha activity.
The methods for gross alpha activity analysis of drinking water are often based on sample evaporation and heating at the temperatures exceeding 100 oC. At such temperatures, can 210Po become volatile in dependence of its chemical form and therefore the gross alpha activity can be underestimated. Our contribution will compare and discuss several routines of sample preparation considering the possible losses of 210Po.
(Nuclear Physics Institute AS CR, Na Truhlarce 39/64, 180 86 Prague)
k<sub>0</sub>-INAA using comparator and neutron flux monitor at CDTN/CNEN, Brazil: advantages and disadvantages20m
Many laboratories apply the k0-INAA and several of them use comparators and spread sheet instead of neutron flux monitors and software for analysis and calculations. At the Laboratory for Neutron Activation Analysis, CDTN/CNEN, two variations of the k0-INAA are used, one is called in house k0-“monostandard” method - using comparator - and the other is the well known k0-standardization method - with neutron flux monitor. The first one, k0-“monostandard”, is an alternative method and it is used in some specific situations. This method is carried out with sodium as comparator, the values for f and α are average values for the carousel facility of the TRIGA MARK I IPR-R1 reactor and each sample is irradiated in one irradiation channel. The calculations are carried out with spread sheet.
Concerning the k0-standardisation method, it is applied irradiating the samples pile in the irradiation vial and intercalated by neutron flux monitor Al-Au (0.1%) IRMM-530RA foil cut into 6 mm diameter and 0.1 mm thick. The irradiation is performed in one irradiation channel in which the values for f and α were determined in this specific channel. For the calculation of the elemental concentrations, a software package called Kayzero for Windows is used.
In this paper, advantages and disadvantages of both procedures are discussed basing on the results of the reference material GBW 07401 (soil) analysed by both procedures.
DrMaria Angela Menezes
(Nuclear Technology Development Centre / Brazilian Commission for Nuclear Energy, Division for Reactor and Analytical Techniques, Belo Horizonte, Brazil)
Measuring of gross α and β activity by means of LSC20m
Measuring of gross alpha and beta activity of radioactive aerosols is one of the tasks of field analyses of radioactive substances in the army of the Czech Republic. It is performed by suction of air through filters and measuring of gross activity. Furthermore the field analyze includes determination of gross alpha and beta activity of water, milk, soil, food, smear and gamma spectrometric measurement.
The problem of determination of gross alpha and beta activity of aerosols filters by means of LSC is solved. This method is perspective and appropriate for rapid measurement of gross alpha and beta activity because of alpha and beta separation, thus simultaneous measurement of alpha and beta radionuclides and 4π geometry without any filter modification.
The method is based on Automatic TDCR Liquid Scintillation Counter Hidex 300 SL. Model radionuclides were chosen due to their military significance, radio toxicity and possibility of misusing by terrorists - 90Sr, 210Pb, 239Pu a 241Am.
Three type of filters were investigate – paper and glass filters in LSC cocktail insoluble and soluble or partially soluble nitrocellulose filters. The attention was also paid to selection of convenient type and volume of the LSC cocktail.
Mercury in Bach Ho crude oil of Vietnam as determined by k<sub>0</sub>-based instrumental neutron activation analysis20m
The k0-based instrumental neutron activation analysis (k0-INAA) using the Dalat research reactor of 500 kW nominal power with a thermal neutron flux about 3.5 1012 cm-2.s-1 has been studied and developed in order to determine Hg (total) in Bach Ho crude oil of Vietnam. Both radionuclides 197Hg (2.7d half-life, 77.3keV gamma-line) and 203Hg (46.6d, 279.2keV) were used with different irradiation and measurement modes in order to calculate the concentration of the element. An evaluation of the limit of detection, precision and accuracy as well as convenience in the use of the two radionuclides was performed. The corrections of spectral interferences by 75Se (119.8d, 279.5keV) on 203Hg and the deconvolution of complex multiplets in region of 70-85 keV for 197Hg and the problem of Hg loss during irradiation were considered. The mean concentration and range of concentrations of Hg in Bach Ho crude oil of Vietnam were obtained through the analysis of 90 samples and the statistical processing.
DrLuong Hien Duong
(Joint Venture “Vietsovpetro”)
Metal detection in solution by new mass-spectrometrical method20m
New method - extraction ions from solution at apmospheric pressure - analog of well-known ESI-MS method was proposed for analysis of metals in radioactibve solutions. Advantages of this metod to compare with known methods - ( ICP-MS, ICP OES, ESI-MS etc.) - small volume of sample, high sensitivity, possibility of automatization.
Modification of precise technique for determining Pu mass fraction by automatic coulometric titration method20m
Technique for determining plutonium total mass fraction in Pu preparations and uranium-plutonium mixtures, including MOX fuel for fast reactors by the automatic coulometric titration is developed and successfully used in RIAR for a long time. The paper presents the optimization results of sample preparation and titration conditions on the facility, developed in RIAR to minimize the total analysis error. Use of standard (CO) potassium dichromate specimen without СО PuO2 for facility calibration during analysis result verification is experimentally proved. Metrological certification of the developed technique version indicated that total analysis error of the Pu mass fraction in the specimen can be less than 0.05%. First, the developed precise technique for plutonium determination was applied during the certification of State PuO2 standard specimen of the first class for its plutonium mass fraction content.
(Russia, Rosatom, JSC"State Scientific Center-Research Institute of Atomic Reactors", Radiochemical Unit)
NORM at indoor environments using aerosols passively collected at classrooms of Lisbon basic schools20m
This work aims to develop methodologies to characterize the composition of the total particulate matter (TPM), collected inside classrooms of three basic schools, in Lisbon, Portugal. The selection of the schools was based on different proximity to city centre: one at downtown, other at the city border and the other at middle distance between both. Quartz and polycarbonate filters are being used. Each filter has a 47 mm diameter and was exposed inside plastic Petri slides. TPM masses are being collected passively during 2009/2010. Although the filters are being exposed inside a small area, significant differences between the masses are observed. Exposed filters and blanks are being measured during a 3 days period in a gamma-X hyperpure germanium detector aiming the detection of natural radionuclides.
The following natural radionuclides could be found: 1) 210Pb, 214Pb, 214Bi, 226Ra, 234Th with origin in 238U, 2) 212Pb and 228Ac originated from 232Th, 3) 208Tl originated from 237Np, 4) 40K originated from 39K. Millipore polycarbonate filters were quite adequate for all measurements except for 210Pb, 226Ra and 234Th, for which quartz filters were found to be more suitable. Results are compared with literature ones and discussed under the point of view of their origin. Methodologies are developed in order to get accurate efficiency calculations for the 47 mm diametr filters.
DrMaria do Carmo Freitas
(Instituto Tecnológico e Nuclear - Reactor)
Optimisation of neutron flux parameters determination for k<sub>0</sub> standardization during irradiation at reactor LVR-15 in Řež20m
Multipurpose research reactors such as LVR-15 in Řež require frequent monitoring of neutron flux parameters (f, α) when k0 standardization in NAA is to be used. These parameters may change quite unpredictably, because experiments in channels adjacent to those used for NAA frequently require a change of the reactor operation parameters and/or active core configuration. For monitoring of the neutron flux parameters in each irradiation container the bare triple monitor method is very convenient. However, when using Zr-Au monitors we have observed quite some variations of f and α values as a function of irradiation and decay time employed. This was especially noticeable if the irradiation time was very short (in case of short-term irradiation induced activities of monitors are too low) or if the decay time before the first count of these monitors was longer than the recommended decay time of one day (the long-term irradiated samples may be too hot to be handled and/or measured one day after irradiation). Therefore, we have tested other sets of neutron flux monitors consisting of Au, Mo and Cr (Au, Mo and Sc in case of short-term irradiation) as proposed recently by Koster-Ammerlaan et al.1
1. M.J.J. Koster-Ammerlaan, M.A. Bacchi, P. Bode, E.A. De Nadai Fernandes, Appl. Rad. Isotopes, 66 (2008) 1964.
(Nuclear Physics Institute, Czech Academy of Sciences)
Pulse shape analysis to reduce the background of BEGe detectors20m
Three methods for reducing the background, and thus the detection limits for gamma spectrometry using HPGe-detectors are combined here.
1. A passive reduction of the background is achieved by using radiopure materials for the detector and its shield
2. An effective shielding from cosmic rays is achieved in the laboratory, which is located 225 m underground.
3. An active background reduction is achieved using pulse shape analysis.
Since the invention of the Ge-detectors in 1962 researchers have investigated ways of using the pulse shape for discriminating between pulses from various types of interactions in the Ge-crystal. The lack of success in this field has triggered developments of more complicated detector systems such as segmented crystals, pixels and strip detectors. When p-type point contact Ge-detectors with a shaped electric field (called BEGe-detectors, Broad Energy Germanium, by the company Canberra) started to appear on the market, the possibility opened for using solely the pulse shape of the one electrode for making analysis.
The drift of the electrons and holes towards the electrodes produce different pulse shape depending on how and where the energy of the photon was deposited in the crystal. When all the energy is deposited in one point, single-site event (SSE), the pulse shape has one peak, but when the energy is deposited is several points, a multiple-site event (MSE), the shape of the pulse present several peaks.
The work presented here aim at study and characterise the background and pulse-shape of two BEGe detectors with 19% and 50% relative efficiency by using a pulse shape discrimination technique. Since the signal of the read-out electrode depends on the size of the detector the discrimination level that can be achieved with each detector is different.
DrRaquel González de Orduña
(European Comision, Joint Research Centre, Institute for Reference Materials and Measurements)
Rapid and simultaneous determination of neptunium and plutonium in environmental samples by extraction chromatography using sequential injection and ICP-MS20m
An automated analytical method for the rapid and simultaneous determination of plutonium and neptunium in environmental samples was developed. Extraction chromatographic column packed with Eichrom TEVA® resin was incorporated in a sequential injection (SI) system to automatically separate plutonium and neptunium from matrix elements and interfering radionuclides. Since valence adjustment is a crucial step to warrant the same chemical behavior of plutonium and neptunium on TEVA column, and therefore actualize their simultaneous separation and detection, we investigated and compared distinct methods for the valence adjustment of plutonium and neptunium to Pu(IV) and Np(IV). The results showed that two steps valence adjustment using disulfite and concentrated nitric acid as redox reagents was the most effective method. The analytical results for both plutonium and neptunium in three reference materials were in agreement with the reference or informative values at the 0.05 significance level. The column separation time within the SI system for a single sample was less than 1.5 hours. The developed method significantly improves analysis efficiency and reduces labor intensity, and enables a rapid and simultaneous determination of plutonium and neptunium which is especially important in emergency situations.
(Radiation Research Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde, Denmark)
Routines of <sup>210</sup>Po determination in fluvial sediments for dating purpose20m
During the last decades, 210Pb and its daughter 210Po have become widely used radionuclides for sediment dating. In environmental sediments, the total amount of 210Pb is given by two components: (a) supported 210Pb, produced by radioactive decay of 222Rn inside the material, and (b) an unsupported 210Pb component derived from 222Rn which diffuses into the atmosphere where decays. Subsequently, 210Pb is removed by atmospheric precipitation or dry deposition, falling on the land or water surfaces.
The dating method often applies determination of 210Po supposing the radioactive equilibrium with 210Pb. Utilized analytical procedures generally consists from several basic parts: (a) isolation of measured radionuclide by leaching or total decomposition of sample matrix or polonium distillation; (b) measurement by alpha spectrometry or by liquid scintillation counting; (c) determination of supported 210Pb. Our contribution will compare several sample preparation techniques and possibilities of measurement with regards to sample matrix, time and instrumentation requests.
(Nuclear Physics Institute AS CR, Na Truhlarce 39/64, 180 86 Prague)
Separation, preconcentration of lanthanum from monazite and its determination by <sup>138</sup>La using non-destructive γ ray20m
A method developed for separation preconcentration and determination of Lanthanum elements which consists of mainly two isotopes, the stable La-139 and the radioactive La-138 with its half life 1.05 E-11 years. The stable isotope La-139 is being the most abundant ratio 99.911±0.001% while La-138 has only 0.089±0.001% abundance ratio. Lanthanum-138 also has two main gamma ray energy lines one at 788.4 and the other at 1435.8 keV which were using for the determination of La-139 by Hyper Pure Germanium detector, HPGe. Based on this method, the percent of La-139 has been calculated with high precision in a synthetic samples. The results were compared with inductively coupled plasma- mass spectroscopy, ICP-MS, technique. The detection limit was calculated as MDA (minimum detection activity) and it has been found to be equal 1.46 Bq/kg for La-138 at 788.4 Kev and 1.52 Bq/kg at 1435.8 Kev gamma ray energy lines with mean value 1.49 Bq/Kg. Application of that method was successfully applied for the determination of lanthanum in natural sample; Monazite. The developed method was based on new chemical steps; precipitation and solvent extraction for such crude specimen monazite sample, for the lanthanide determination was established. Where, the precipitation method is used for removal of Th (IV) and U (VI) and the solvent extraction is used for removal of Ac from REEs. Molar Solution HDEHP in benzene was applied to extract REEs and Actinium, Ac, from 0.1M HNO3 while the 0.2M HNO3 is used to stripe Ac leaves REEs in the organic phase. Therefore, lanthanum in the residual REE was accurately determined.
(Atomic Energy Authority, Hot lab center, Analytical Chemistry Departments,)
The use of coincidence summing effect in γ spectrometry for the determination of full energy photopeak efficiency and activity of the <sup>60</sup>Co-60 point source20m
A study of coincidence summing of gamma-rays of Co-60 has been presented. In
gamma-ray spectrometry with germanium detectors, the summing effect have to be taken into account at low source detector distance. The peaks due to coincidence summing of X+X, X+gamma,gamma+gamma rays can complicate the spectrum obtained by this type of the detector and signicantly change the counting rate of single peaks. There is theoretical model developed for coincidence summing of X and gamma rays for radionuclides with complex decay scheme. This models enables to write equation for single peaks, the coincidence sum peaks and total count rate. The efficiency of detection and the activity of Co-60 source are the unknowns in the count rate equation system. They can be determined by simultaneously finding the roots of the equation system.
Transfer coefficients from soil to roots of wheat plants by INAA20m
An extensive investigation of elemental levels in cereals and their cultivation soils is being carried out across the main production areas of mainland Portugal, with a view to an eventual Se-biofortification of major cultivars (under research contract PTDC/QUI/65618/2006; FCT-MCTES, Portugal). Breads and cereal derivatives (breakfast blends, pastas, etc) make up a sizeable share of the Portuguese diets, thus an increase in the bioavailability of essential elements through crop biofortification may contribute to an upgrade in the health status of the whole population. For this purpose of nutrient supplementation, and accounting for its relative weight in the realm of cereal consumption, samples from two areas with an intensive wheat production (bread and durum; Triticum aestivum L. and Triticum durum L., respectively) were collected through the summer of 2009. Such areas are located north and south of the Tagus river, deep into the inner territory of mainland Portugal. This work aims at an elemental characterisation of the cereal-cultivation soils, and their role in the nutritional uptake of wheat plants. Four certified reference materials were used for the quality control of the analytical technique here (instrumental neutron activation analysis = INAA): NIST-SRM 1567a (Wheat Flour), NIST-SRM 1568a (Rice Flour), GBW07404 (NRCCRM Soil NCS DC 73322) and GBW07406 (NRCCRM Soil NCS DC 73324). For NIST-SRMs, only a few elements were above detection limit in the present conditions - As, Br, K, Na, Rb, Se, Zn - even if in good agreement with their certified values, accounting for uncertainties. The elements that could be compared with certified values for the Chinese soils were: As, Br, Ce, Co, Cr, Cs, Cu, Eu, Fe, Ga, Hf, Ho, K, La, Lu, Na, Nd, Pr, Rb, Sb, Sc, Sm, Ta, Tb, Th, W, Yb, Zn and Zr. Overall, a good agreement was found as well. Wheat-cultivation soils from the area south of Tagus river contain higher concentrations of As, Cs, Ga, K, Rb, Ta, Th, U, W and Zn, thus featuring adequate levels of nutrients such as Cs, K, Rb or Zn. The northern-area soils contain higher concentrations of Co, Cr, Eu, Fe, Hf, Na, Sb, Sc, Tb, Yb and Zr, and feature large amounts of the nutrients Co, Cr, Fe and Na. Similar results were obtained for Br and the rare earths Ce, Ho, La, Nd and Sm. Some differentiation of rare-earth elements occur for Eu, Tb and Yb, i.e., for the heavier ones. No depletion or enrichment was found for Ce, since its ratio to La is 2. For wheat roots, Cd and Hg were found in some samples at levels of 1 and 0.1 mg per kg dry weight (d.w.), respectively. The highest soil-plant transfer coefficients (root d.w. contents/soil d.w. contents) were found for Br, Cr and Zn (above 30 %), followed by As, Co, Ga, K, Tb, U and W (between 10 and 20 %), whereas the lowest values (below 10 %) were found for Ce, Cs, Eu, Fe, Hf, Ho, La, Na, Nd, Rb, Sc, Sm, Ta, Th, Yb and Zr.
(CERENA-IST, Technical University of Lisbon)
Tritium content distribution in Jeju island groundwater using Ni-Ni electrolytic enrichment method20m
Jeju is a volcanic island located about 90 km south of the Korean peninsula. This area is covered with highly permeable basaltic rocks from the Pliocene through the Quaternary. These rocks are highly permeable and forming the principal aquifers. Therefore, ground water is the sole fresh water resource and provides almost all of the water demand because of the low content of the surface water.
In this work, tritium levels in Jeju island groundwater were studied with a liquid scintillation counter(LSC) and electrolytic enrichment method using Ni-Ni electrodes. Tritium enrichment parameters are estimated with different current and total current charge variation. From the established optimum tritium enrichment condition, we analyzed fifty eight mountainous area groundwater samples of Jeju island.
The tritium separation factor was from 8 to 36 with a current density variation. The detection limit of tritium measurement is about 0.06 Bq/L using 1000 mL sample and 600 min counting time. The tritium concentrations in fifty eight groundwater in Jeju island were ranged <0.06 TU-0.46 Bq/L and averaged value was 0.25 Bq/L.
DrYoon Yeol Yoon
(Korea Institute of Geoscience and Mineral Resources)
Poster Session - Production and Application of RadionuclidesGallery
An external cyclotron target system for nanoparticle sample activation20m
The need for toxicity assessment of industrially relevant nanoparticle materials implies that in vitro and in vivo biokinetics studies are required. Radiolabelled nanoparticles are an excellent candidate for such biodistribution measurements and are also of high interest for particle tracing and fate studies in other areas.
We describe here an external target system for direct activation of dry nanoparticle samples, with He or water cooling, which is attached to an external beamline of the JRC Scanditronix MC-40 cyclotron at Ispra, Italy. A specially designed capsule is used to hold several tens of mg of nanoparticle powder material to be irradiated. The target system design and cooling system is described, and considerations regarding energy deposition, yield, heat transfer, radiation damage and radiotracer recoil are discussed.
Acknowledgement: This work was performed in support of several projects, including the European Commission’s 7th framework programme "NeuroNano" project – contract number NMP4-SL-2008-214547
Characterization of a Cu selective extraction chromatographic resin20m
Cu isotopes (e.g. Cu-64) increasingly find use in radiopharmaceutical applications, accordingly fast and reliable methods for the production of these isotopes are needed. Aim of the presented project is the characterization of a Cu selective extraction chromatographic resin for the fast and selective separation of Cu radionuclides e.g. from irradiated Ni targets. The characterization of the resin includes the determination of k’ values of Cu, Ni and other potentially interfering elements and impurities for varying acids and pH values, the influence of macro amounts of Ni on the extraction of Cu as well as the influence of other potential interferents. Based on the obtained results a method for the separation of Cu, and its purification, from irradiated Ni targets was developed and tested on simulated Ni targets.
Comparative study of the corrosion and surface analytical effects of the decontamination technologies20m
Decontamination technologies are generally developed to reduce the collective dose of the maintenance and operation personnel at NPPs. The highest efficiency (i.e., the highest DF values) available without detrimental modification of the treated surface of structural material is the most important goal in the course of the application of a decontamination technology. The AP-CITROX procedure has mainly been used for the decontamination of the primary coolant circuit’s components (e.g. main circulating pump (MCP) and steam generators (SGs)) at the Paks NPP. While decontamination of the dismountable devices (e.g. main circulating pump) has been carried out in big tanks with heating potential, separable equipments (e.g. heat exchangers) have been treated with special decontamination facilities.
The AP-CITROX procedure was used 24 times for the SGs decontamination at units 1-3 of the Paks NPP during the period of 1993-2001. Our previous studies have revealed that a ”hybrid” structure of the amorphous and crystalline phases is formed in the outermost surface region of the austenitic stainless steel tubes of SGs as an undesired consequence of the industrial application of the AP-CITROX decontamination technology.
In this presentation, we report some comparative findings on the corrosion and surface analytical effects of the AP-CITROX procedure and the decontamination technology elaborated at our institution. After optimizing its operational parameters the latter technology is suitable for the decontamination of both dismountable (e.g. MCP swivel) and separable (e.g. heat exchanger) equipments. In this semi-plant scale experiments, the passivity, morphology and chemical compositions of the treated surfaces of tube specimens were investigated by voltammetry, and SEM-EDX methods.
The newly developed decontamination technology can be effectively applied for the decontamination of the austenitic stainless steel samples; the total oxide-layer can be removed by this technique. The SEM-EDX results revealed that the oxide removal is surprisingly uniform even after 2 or 3 consecutive cycles. The electrochemical studies provided evidences that no unfavorable tendencies in the general corrosion state of the tube samples can be detected in the course of the chemical treatments.
Keywords: decontamination, AP-CITROX, voltammetry, SEM-EDX
(University of Pannonia Institute of Radiochemistry and Radioecology)
Comprehensive investigation of the corrosion state and surface properties of the stainless steel tubes of steam generators20m
Evaluating the water chemistry in the primary circuit and the effect of chemical decontamination of the heat exchanger tubes performed by the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) procedure at Paks NPP (Hungary), a project dealing with the comprehensive investigation of the general corrosion state of the steam generators (SGs) has been initiated. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research program based on sampling as well as on ex-situ electrochemical (voltammetric) and surface analytical measurements (SEM-EDX, CEMS, XRD, XPS) was developed and elaborated.
In the time period of 2000-2008 - within the frame of the above project - 45 stainless steel specimens, cut out from various locations of the steam generators of the Paks NPP were investigated. Based on the measured corrosion characteristics (corrosion rate, thickness and chemical composition of the protective oxide-layer) it was found that these parameters are strongly dependent on the decontamination history of steam generators. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.
Keywords: stainless steel, steam generator, corrosion, decontamination
MrsAndrea Szabó Nagy
(István Széchenyi University Department of Physics and Chemistry)
Isotopic effect observed by distillation of <sup>123</sup>I and <sup>124</sup>I from irradiated <sup>124</sup>TeO<sub>2</sub> target matrix20m
Non-conventional longer-lived PET radionuclides with half-life higher than that of 18F (109 min) are very promising PET tracers for imaging of biochemical processes or body structures requiring slower kinetics. Among them, 124I (4.18 d) plays an important role. Radiochemistry of iodine radioisotopes (123I, 124I, 125I and 131I) is well known. Widely used production process of 124I is based on the (p,n) reaction on highly enriched 124TeO2 (99.4 %), and distillation of iodine from irradiated target matrix at temperatures slightly above the melting point of TeO2 (733 °C). Depending on the entrance beam energy, some amount of 123I can be produced by the (p,2n) reaction (Ethr ≈ 11.5 MeV).
For production we have developed our own target system. Target layer is water and helium cooled. The target was irradiated at the beam angle 10° in order to increase effective thickness of the target layer and to get more favourable distribution of the beam over the target area. The entrance proton beam energy varied between 11.5 and 13.2 MeV, beam currents were 10–22 µA and irradiation times 0.5–2 h. The distillation was performed in pre-heated quartz tube (735–750 °C). The radioiodine was carried out with stream of air. The flow rate was set to 25 mL/min. Evaporated iodine was trapped in 0.01M NaOH. Time of separation was 15–20 min.
Radionuclidic purity and activity of produced isotopes was measured with γ-ray spectrometry using HPGe detector, in all steps of production (irradiated target, target after distillation and solution of separated product). Since the protons’ entrance energy was higher then treshold of the (p,2n) reaction, we also measured activity of the co-produced 123I. We have observed an interesting effect. The ratio of decay-corrected activities of 123I and 124I in the target matrix after the separation of radioiodine was 2–3 times higher than in the target matrix after irradiation. In accordance to this effect, we also observed that ratio of decay-corrected activities of 123I and 124I in the solution of separated product was proportionally lower than the ratio in target.
(Nuclear Physics Institute of the ASCR, v.v.i.)
Measurement of excitation functions for (d,x) reactions on natural molybdenum20m
Cross sections for deuteron induced reactions on natural molybdenum leading to 93Tc, 93mTc, 94Tc, 94mTc, 95Tc, 95mTc, 96Tc, 96mTc, 99mTc, 99Mo, 92mNb, 95Nb and 89Zr were measured in deuteron energy range 9.0–19.6 MeV on the cyclotron U-120M of the Nuclear Physics Institute AS CR. Special attention was paid to excitation function for formation of 95mTc, which is used as a tracer for determining 99Tc in environmental samples, and to excitation functions and thick target yields for formation of 99mTc and 99Mo, the most widespread radionuclide generator pair in nuclear medicine. If appropriate, obtained data are compared with the heretofore published cross sections.
(Nuclear Physics Institute, Academy of Sciences of the Czech Republic)
Preparation and characterization of target for <sup>64</sup>Cu production on the IBA 18/9 Cyclotron.20m
Copper has many radionuclides (60Cu, 61Cu, 62Cu, 64Cu, and 67Cu) that can be used in nuclear medicine and molecular imaging. Isotope 64Cu (Iβ+= 17.6 %, Eβ+max=653 keV, Iβ-= 38.5 %, Eβ-max=579.4 keV ) is positron emitters and half life 12.7 hrs and is suitable for the preparation of radiopharmaceuticals for PET imaging. The 64Ni(p,n)64Cu reaction route is popular for its preparation because its entrance channel is accessible at low energies and yield of reaction is quite high. Disadvantage of the reaction used is a high price of the enriched 64Ni. Thick gold or platinum target were used for target preparation by electrodeposition. Irradiation surface of target was optimized for COSTIS station. COSTIS target station was installed at the end of the external beam line of the IBA Cyclone 18/9 cyclotron. The target station has been equipped with aluminum or Nb window foil in front of the target to degrade energy to optimal energy for nuclear energy less then12 MeV. Since the external beam line of the cyclotron has no beam diagnostic devices, several aluminum plates were irradiated in the COSTIS target station with a 5 µA proton beam for 15 min. with different settings for the beam focusing quadrupole magnets. After one day decay time the plates were scanned by a TLC scanner along the horizontal and vertical central axes of the plates in order to visualize the beam shape. The settings providing most homogeneous beam spot on the target were selected and used further for the real target irradiations. Presentation will concerns of preparation, optimization of target for irradiation in COSTIS target station, separation procedure and characterization of 64Cu radiochemical prepared.
(Biont, Faculty of Natural Sciences, Bratislava, Slovakia)
Preparation of <sup>95m</sup>Tc radiotracer20m
Several procedures of the preparation of the radionuclide 95mTc, a radiotracer useful for vari-ous purposes, were tested. A foil made of natural molybdenum was irradiated with protons or deuterons and after 5-6 weeks of decay the 95mTc radionuclide was separated. Three different separation procedures were tested. 1) Alkaline-oxidative fusion of the Mo target with sodium peroxide and sodium hydroxide followed by the dissolution of the melt in water and liquid-liquid extraction of Tc with methyl ethyl ketone. The organic phase with Tc was evaporated and the residue was dissolved in 2 M HNO3. 2) The target was dissolved in the mixture of hot concentrated HNO3 and H2O2. The solution was evaporated, the residue was dissolved in 0.1 M HCl and Tc was separated by extraction chromatography with a Tc selective chroma-tographic resin (PAN-Aliquat 336 with similar properties as Teva® Resin). 3) The molybde-num foil was dissolved in the mixture of concentrated H2SO4 and HNO3 (25:1) using micro-wave assisted digestion. To remove sulphate ions, which would interfere in the subsequent separation, barium chloride was added to the solution, the precipitate of barium sulphate was separated by filtration, and Tc was separated from the aqueous phase by extraction chroma-tography as given above. The column was washed with 1 ml of 0.1M HCl and Tc was stripped with 5 ml of 8 M HNO3. The overall separation yield was in the range of 70 to 95 %.
All the three methods can be used for Tc separation. However, the following difficulties have been encountered in the first two methods. In the first method, it is necessary to repeat the alkaline fusion step since the amount of reagents in one fusion is to be limited due to a very reactive nature of the flux used. Consequently, the liquid-liquid extraction step is to be re-peated several times. In the second method tested, a precipitate of undetermined composition appears during dissolution, which, unfortunately, contains about 25 % of 95mTc present in the target. The third method appeared superior over the other two methods tested, because it is fast, simple and provides a very good separation yield of technetium (> 90%).
(Nuclear Physics Institute ASCR)
Recovery and isolation of hafnium isomers from <sup>176</sup>Yb target irradiated by <sup>4</sup>He ions in optimized conditions20m
Interest to high-spin (16+) long-lived (31 y) 178m2Hf isomer was established since 20 years ago because of a possibility to produce it in a micro-weight amount for consecutive studies of nuclear reactions with high-spin target and for potential application as an energy accumulator. Production of 178m2Hf was described in  via spallation of Ta by protons at LAMP facility and via 176Yb(4He,2n) reaction at Dubna cyclotron . Series of experiments with the 178m2Hf target had been carried out due to cooperation of FLNR with European research centers and the results were summarized in  and refs. therein. On today, the innovative perspectives for creation of tiny energy sources support the continuing interest to 178m2Hf.
In the present report, we describe an optimized production of 178m2Hf using the 176Yb target of special construction irradiated at internal beam of the U-200 cyclotron in Dubna. The 96% enriched 176Yb oxide was deposited onto water-cooled Al backing, and the target surface was inclined to the beam at angle near 10 degrees. The target thickness of 7 mg/cm2 has provided effective thickness in a beam direction of about 80 mg/cm2 in ligature weight. The 4He+1 ions reach an energy of 35 MeV. With beam intensity limited to be lower 15 microA, the corresponding beam power does not exceed 500 W. Such conditions were safe, but the target could stand even at 3 times higher beam intensity. After irradiation the target material Yb2O3 was washed off from the backing with 16 M HNO3 and anion exchange in conc. HCl solution was applied to separate Hf-fraction. With the same purpose precipitation of YbF3 was also tested . Deep purification was carried out using the anion exchange chromatography in HF solutions with an overall chemical yield upon the average 85%. Activity of the irradiation products was controlled by the gamma-spectroscopy method using HPGe spectrometer. All gamma-lines belonged to 178m2Hf and 179m2Hf were quantitatively measured and absolute yields of both high-spin isomers were determined with appropriate accuracy.
Under described conditions several 176Yb targets were irradiated, and, in total, 6e+14 atoms of 178m2Hf were produced over beam time of 900 hours. The isomer cross-section and impurities content obtained in the present experiments are in a good agreement with the data published earlier . Change to the internal beam at the cyclotron and more tangential beam-to-target geometry supply higher yield of the products and make the production method more economic. The position of a target inside the cyclotron camera leads to the decreased neutron flux outside and meets the requirements of modern radiation safety rules. Improving the biological shielding at the accelerator and increasing the beam current, one can expect a productivity of about 3e+15 of the 178m2Hf isomeric material per 1000 hours of effective irradiations.
1. W.A. Taylor, J.G. Garcia, V.T. Hamilton, et al., J. Radioanal. Nucl. Chem., 236, 155 (1998).
2. Y.T. Oganessian, S.A. Karamian, Y.P. Gangrski, et al., J. Phys. , G, 18, 393 (1992).
3. S.A. Karamian, Acta Phys. Pol. B, 26, 375 (1995).
4. N. V. Aksenov et al., contribution to this conference.
(Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research), MrNikolay Aksenov
(Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research)
Selective Retention of U (VI) and U (VI) Chemical Species on Eichrom Resins20m
("Al.I. Cuza" University, Faculty of Chemistry)
Separation of <sup>131</sup>Cs from barium radionuclides20m
Khujaev S., Markelova E.A., Vasidov A.
Institute of Nuclear Physics, Tashkent, Uzbekistan
The implanted seeds of the Cs-131 are successfully uses in brachytherapy to treat prostate cancer and other malignant tumors. The single x-rays of Cs-131 with 30 keV damages and kills genetic materials of cancer cells, making it impossible for these cells to continue to grow while saving or minimizing damage to the healthy tissue. Besides the radioisotope Cs-131 has a short half-life (T1/2=9.7 day), making it is able to deliver a 90% of its dose energy in just 33 days compared to 204 days for I-125 (T1/2=60 day) and 58 days for Pd-103 (T1/2=17 day).
In this work, the radiochemical methods of separation of the Cs-131 from Barium radioactive isotopes are presented. The targets of barium components (BaCl2, BaCO3, BaO) were irradiated for 3-7 days, by thermal neutrons at fluxes of 5-10x1013 cm-2 s-1 of nuclear reactor. As a result of an irradiation have formed about 10 an undesirable radionuclidies, that represents a certain difficulties and radioactive safety at separation of the Cs-131 from radioactive solutions. Carrier-free Cs-131 is separated from the irradiated barium target, by precipitation of Ba2+ cations with addition of SO42- anions in excess and filtration of the formed precipitate. Chemical purity of Cs-131 was determined by gamma spectrometer of the HPGe detector.
Progresses on the structural chemistry of the actinide phosphates30m
Data on structure and properties of actinide phosphates are needed for the development of phosphate ceramics envisaged as possible hosts for long-term sequestration of actinides generated by the nuclear fuel cycle. In that aim an extensive study on the crystal structures, thermal stability, and thermodynamic properties on a number of crystalline trivalent and tetravalent actinide phosphates was undertaken.
PuPO4 with monazite structure was obtained and characterized in terms of thermal stability and thermal expansion. The decomposition of PuPO4 to Pu2O3 was observed at 1573 K. Its high-temperature heat capacity is to be measured up to 1500 K by drop calorimetry.
MIINp(PO4)2 (MII= Ca, Sr, Ba) were obtained by solid state reaction. The influence of ionic radius of MII (MII= Ca, Sr, Ba) on the crystal structure is further discussed. Pure phase of CaNp(PO4)2 with monazite structure (P2/n) was obtained by solid state reaction after several thermal treatments and readjustments in stoichiometry. The lattice parameters are a= 6.65085(3) Å, b= 6.83893(5) Å, c= 6.35378(3) Å, and β= 104.117(9) o. SrNp(PO4)2 seems to adopts an inedited double-monazite structure with a= 6.895 Å, b= 13.272 Å, c= 6.892 Å, and β= 99.22 o, probably due to the Sr/Np ordering responsible for the non-negligible reflections with k = 2n +1; in this case, the two cations seem too different in size to allow disorder, contrarily with CaNp(PO4)2. Pure BaNp(PO4) with monoclinic C2/c was also obtained. Its structure was inferred with the one reported for RbEu(SO4)2, the lattice parameters being a= 12.69095(13) Å, b= 5.36179(6) Å, c= 9.40949(11) Å, and β= 102.516(68) o. The pattern looks similar with the one previously found for the Th-counterpart.
("Al.I. Cuza" University, Department of Chemistry)
Structural aspects of uranyl complexes with lipopolysaccharide15m
It is well-known that microorganisms play an important role in bioremediation. Because of the high retention capability of heavy metal ions, they significantly influence mobilization and immobilization of cations in soils. The prediction of the radionuclide transport in the environment and the improvement of technical bioremediation strategies require a detailed understanding of the binding mechanisms on a molecular level.
Lipopolysaccharide (LPS), the main part of the outer membrane of Gram-negative bacteria, sticks out of the cell wall and is in direct contact with the (aqueous) environment. With its high content of negatively charged functional groups (mainly carboxyl and phosphoryl groups) it plays a key role in protection of contaminants.
We investigated the uranyl LPS interactions to gain detailed information about the coordination sphere in the molecular environment of the uranyl ion. We focused on the identification of the coordinating functional groups over a wide pH range (from 2.5 to 7) and under different stoichiometric conditions. In particular, the discrimination between carboxyl and phosphoryl groups and their binding behaviours was elucidated by extended X-ray absorption fine structure (EXAFS) spectroscopy at the U LIII-edge and attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy. With respect to environmental conditions, samples with an excess of LPS were investigated by EXAFS. Furthermore, samples with equimolar ratios of uranyl and functional groups of LPS according to a slight deficit of phosphoryl groups were determined with FT-IR.
EXAFS spectra show great similarities to the uranyl mineral phase meta-autunite. A four-fold complexation of the uranium was derived from very short U Oeq distances of 2.28 Å and U P distances of 3.58 Å indicating unidentate coordinated phosphoryl groups. Furthermore, U U interactions can be observed at 5.2 Å and 6.9 Å.
FT-IR spectra show spectral evidence for both, carboxyl and phosphoryl coordination. A downshift of the antisymmetric stretching mode of the carboxylate group from 1576 (uncomplexed LPS) to 1530 cm−1 and an upshift of the symmetric stretching mode from 1404 (uncomplexed LPS) to 1455 cm−1 upon complexation provides evidence for a bidentate complexation to carboxylate groups. The antisymmetric and symmetric stretching modes of the complexing phosphoryl groups are observed at 1105 and 1060 cm−1.
In summary, we determined at high LPS excess preferential phosphoryl coordination, whereas with an increasing relative amount of uranyl ions, corresponding to a decreasing number of functional groups of LPS, additional carboxylate coordination becomes important. This complexation behaviour remains within a broad pH range from slight acidic to neutral values. Under the investigated experimental conditions, the coordination of uranyl ions to the LPS molecule is obviously controlled by the U/LPS concentration ratio irrespective from prevailing pH.
(Institute of Radiochemistry, Forschungszentrum Dresden-Rossendorf)
Complexation of curium(III) with pyoverdin-model compounds15m
The aerobic groundwater bacterium Pseudomonas fluorescens (CCUG 32456) isolated from the aquifers at the Äspö Hard Rock Laboratory, Sweden secretes siderophores of the pyoverdin-type. Besides iron(III), these unique bioligands are also able to form strong complexes with actinides (e.g., U(VI), Np(V), and Cm(III)) [1-3]. For U(VI) and Np(V) we could show that mainly the catecholate and to less extend the hydroxamate functionalities of the pyoverdin molecule are involved in the actinide coordination [1, 2]. For Cm(III) it is still not clear which functional group of the pyoverdin molecule causes the great stability constants. In general, Cm(III) interactions with pyoverdin-model compounds and especially with chromophore-models are poorly understood. To address this lack, we thus present findings regarding the speciation of Cm(III) with 2,3-dihydroxynaphthalene in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at trace Cm(III) concentrations (0.3 µM) over a wide pH range. TRLFS is a well established direct speciation technique for investigating the complexes formed by actinides in both geochemical and biochemical environments. Four Cm(III)- dihydroxynaphthalene species of the type MxLyHz could be identified from the spectroscopic measurements. The stability constants of these strong Cm(III)- bioligand complexes and their individual spectroscopic properties (excitation and emission spectra, lifetimes) are reported. TRLFS shows that Cm(III)- dihydroxynaphthalene species cause a strong red shift of the characteristic Cm(III) (aq) emission band at 593.8 to 614.4 nm. The findings of our Cm(III) speciation study in comparison with the literature indicate a stronger affinity of Cm(III) to the catechol functionality of the pyoverdin molecules as found for U(VI) and Np(V).
 H. Moll, M. Glorius, G. Bernhard, A. Johnsson, K. Pedersen, M. Schäfer, H. Budzikiewicz, Geomicrobiol. J. 25, 157-166 (2008).
 H. Moll, M. Glorius, A. Johnsson, M. Schäfer, H. Budzikiewicz, K. Pedersen, G. Bernhard, Radiochim. Acta, submitted (2009).
 H. Moll, A. Johnsson, M. Schäfer, K. Pedersen, H. Budzikiewicz, G. Bernhard, BioMetals 21, 219-228 (2008).
This work was funded by the BMWi under contract number: 02E9985.
Joint determination of <sup>99</sup>Tc and <sup>108m</sup>Ag in L/ILW liquid wastes15m
The low- and intermediate-level liquid wastes produced by the Paks Nuclear Power Plant (NPP) contain routinely measureable gamma-emitting (e.g. Mn-54, Co-60, Ag-110m, and Cs-137) as well as many so-called “difficult-to-measure” isotopes. Despite of their low specific activity compared to the total, the reliable determination of these isotopes is an important issue of nuclear waste management. The increasing amount of waste samples to be qualified yearly by our laboratory put a pressure on revising the existing procedure of Tc-99 separation applied. We have managed to halve the initial amount of the sample required to achieve the same level of MDA of technetium. Furthermore, one of the new purifying steps introduced have proved to be able to separate Ag-108m (and Ag-110m) better than 99% keeping the Tc-99 content of the product almost intact. As intended, this new procedure has a major impact on the chemical reagent as well as the electricity requirement of the separation making it more cost-effective.
(Nuclear Research Institute, Hungary)
Extraction of thorium from the Fen deposit in Norway15m
After the renaissance of nuclear power and thorium breeding in particular, the interest for the Norwegian thorium deposits has revived. However, the economic potential for exploitation is depending on several parameters, i.e. heterogeneity of ore, content of carbonaceous minerals, other valuable elements present, etc.
Fen is the site where the largest Norwegian thorium deposits are found. The thorium minerals at Fen are reported to be oxide and silicate, but experience obtained indicates that some thorium must also be present in carbonate rock. Based on experience from extraction of rare earth elements from red rock ("rødberg") at Fen the possibilities for thorium extraction are assessed.
The Fen complex in Telemark, Norway is a geological region noted for an unusual suite of igneous rocks. Several varieties of carbonatite are present in the area as well as highly alkaline rocks. The Fen complex is a roughly circular area about three kilometers in diameter. It is located just west of the Oslo graben, on the south side of Lake Norsjø, from Ulefoss in NW some three km eastbound. The area covers some 6 km2 and has been known for its complex mineralogical composition for almost a century.
Rødberg rock in the local area called Gruveåsen is covered with soil and vegetation. Gruveåsen has the highest concentration of thorium in the area. The thorium concentration in Gruveåsen is reported to reach 0,4%, but ordinarily it is 0,1 – 0,2%. Only in Gruveåsen the amount of Th is expected to be of the order of 5 000 tonnes.
The whole Fen area is populated and used as residential and recreational areas.
Not only is the heterogeneity large, the mineral grains are small, less than 0.1 mm.
The content of carbonaceous rock requires a high consumption of acid to leach it. In a pilot plant operation to extract rare earth elements (REE) HCl was chosen as the dissolving species. 700 kg HCl per tonne rødberg was consumed to leach a yield of 100% Ca and Mg and 80% of REE. Thorium was also leached indicating that Th is not solely present as silicate or oxide. However, small amounts of silicic acid were also present in the leachate causing severe problems.
To extract thorium also other valuable elements must be cost carriers and the rare earths are an obvious choice. Another possible element present is niobium, but it is not present in the same minerals as REE.
Thorium from Fen will hardly ever be recovered as the main element, but may be a valuable by-product. However, the main obstacle in developing an economic feasible process is the carbonaceous rocks consuming too much acid or energy.
Technetium chemistry at the University of Nevada Las Vegas15m
The chemistry of technetium is being explored at the University of Nevada Las Vegas. Our goal is to investigate both the applied and fundamental aspects of technetium chemistry, with a special emphasis on synthesis, separations, and materials science. The synthetic chemistry focuses on metal-metal bonding and binary halides. Recently, two new multiply metal-metal bonded dimers and technetium tribromide and tetrabromide were prepared and characterized. These compounds were used as precursor for synthesis of low valent technetium complexes. The structure of (n-Bu4N)2Tc2Br8 was solved by single crystal XRD and its electronic structure analyzed by first principles calculations. Separation and materials chemistry is related to the nuclear industry. The separation of uranium/technetium from acidic solution, and synthesis of Tc containing waste forms have been investigated. The facilities at UNLV include modern radiochemistry laboratories where investigators can work with multi-milligram quantities of 99Tc, and analytical instrumentation dedicated for radioelement characterization and analysis.
Recent developments of nuclear forensic signatures of yellow cakes15m
Natural uranium is the starting material for the production of nuclear fuels. Uranium of natural isotopic composition is mined from uranium containing ores in different geological formations. The uranium is extracted, chemically purified and pre-concentrated. As an industrial scale material, uranium ore concentrates will carry signatures that provide information on the history and on the origin of the uranium. These signatures may be source material inherited or process inherited. In the present work we investigated the significance and potential application of parameters such as the rare earth elemental patterns or strontium and lead stable isotope ratios. The methodology developed and its application to uranium ore concentrates from different mines around the world will be presented.
(EC JRC Institute for Transuranium Elements)
Heteronuclear hydrolysis complex of thorium(IV) and iron(III)15m
The solubility of the Th(IV)/Fe(III) system has been studied as function of pH in the range 2.00-3.50. In the individual systems of thorium(IV) and iron(III) precipitation takes place due to formation of hydrolysis products. However, in the mixed Th(IV)/Fe(III) system precipitation of ferrihydrite takes place at low pH value, pH = 2.00, whereas at higher pH no precipitation was observed after 20 months. The mixed heteronuclear complex of composition [Th2Fe2(μ2-OH)8(H2O)12]10+ was formed in solution, with Th--Th, Th--Fe and Fe--Fe distances of 3.95 and 3.949; 3.42 and 3.4; 3.05 and 2.921 Å as determined by EXAFS and LAXS, respectively. Two and four line ferrihydrite was formed in solutions at low pH values, 2.00-2.30, as identified by X-ray diffraction (XRD). SEM analysis of these precipitates showed that some of them contained only iron, whereas the others contained both iron and thorium. Mixed Th/Fe system showed increased solubility what may affect the design of tanks for spent nuclear waste.
(, Joint Institute for Power and Nuclear Research – Sosny, Belorussian Academy of Sciences, 220109 Мinsk, Belarus)
Radionuclides in the Environment, Radioecology 3Mirror Hall
Tritium in the rainwater around the nuclear power plant of Paks, Hungary15m
Tritium in the environment has natural and artificial sources. The formers are the nuclear reactions in the upper troposphere and the lower stratosphere, the latter are the various nuclear facilities (fission and fusion reactors, etc.). In order to investigate the two phenomena separately it is necessary to know the effect of artificial tritium emitters to their surroundings with respect to distance from the source.
In the presented study rainwater was collected around the nuclear power plant of Paks, Hungary, by means of special rainwater collectors. The sampling distances were 400 and 800 m from the centre of the plant. The samples were analyzed for tritium with liquid scintillation counting and some samples with the 3He ingrowth method.
Results show that the trace of the tritium plume from the plant is clearly detectable in the rainwater. However the maximum activity of the rainwater is only around 10 and 5 Bq/l at 400 and 800 m distances, respectively.
A Gaussian plume model is fitted to the measured tritium and meteorological data and shows that the influence of the plant on the tritium in rainwater is completely negligible over some kilometers distance.
Radiation and environmental monitoring at the sites for the RW and SNF temporary storage in Russia15m
In the light of the operation life termination of the Navy nuclear submarines and their technical service vessels, and because of international obligations of the Russian Federation to reduce armaments, the intensive decommissioning has started since the latter 1980-s. The decommissioning rate was higher than these submarine dismantlement rate determined by the available abilities of the industrial infrastructure. Therefore, radioactive wastes were being accumulated at the sites for the RW and SNF temporary storage (STS), like a shot. From this perspective, ex-Navy shore technical bases located in Murmansk region (Andreeva Bay and Gremikha village) and at the Primorsk Territory (Sysoeva Inlet) are the subjects of the highest attention.
To gather full information on the current radiation situation, independent in relation the regulatory bodies, the FMBC specialists carried out radiation and hygienic monitoring. It included dynamic observation both of the radiation-and-hygienic situation parameters and doses to the public living close to the radiation hazardous facilities – STS in Murmansk region and Primorsk Territory. During the expedition travels, samples of environmental media, local foodstuffs and drinking water have been collected. Radiochemical analysis and gamma-spectrometry methods were used in the sample examination. The findings of radiation and environmental monitoring confirm considerable exceeding (in comparison with normal background values) of man-made radionuclide contents in seawater, seaweeds, bottom sediments, vegetation and soil at local parts of the coastal stripe of the STS health protection zone. The radionuclide sorption examination in soil and ground water permits to assume effective migration from the contaminated areas via ground water and following radioactivity intake by the marine media at the off-shore water area. Taking into account further contamination of the STS area, observation of the radiation situation dynamic change should be continued both under regular operation mode and during the SNF and RW removal operations.
(Burnasyan Federal Medical Biophysical Center, Moscow, Russia)
Photo- and radiation-induced preparation of nanocrystalline copper and cuprous oxide catalysts15m
Radiation method of copper and cuprous oxide preparation produces material of high chemical purity and catalytic activity. Reduction of metal ions in aqueous solutions via UV, γ irradiation or accelerated electrons results in formation of nanosized particles of both Cu/Cu2O with uniform spherical shapes at normal temperature. This method of preparation is very simple and relatively efficient; it requires mostly only one additive – ∙OH scavenger – in order to promote process of reduction. Oxygen present in water readily oxidises formed nanoparticles of non-noble metals and causes their dissolution; therefore the solutions must be deaerated prior to irradiation.
In this work, aqueous solutions containing copper sulphate or formate (0.001 to 0.01 mol.dm-3) in the presence of ∙OH scavenger propan-2-ol (1.3 mol.dm-3) and surfactant polyvinyl alcohol PVA were irradiated. Following radiation sources were used: Medium pressure mercury lamp with power input 400W for UV irradiation, LINAC 4-1200 for electron irradiation and 60Co radionuclide source Gammacell 220 for γ irradiation. Effects of radiation were evaluated using UV-Vis absorption spectrophotometry, SEM and XRPD. Catalytic activity of prepared Cu2O powder was studied by measuring the rate of catalytic decomposition of hydrogen peroxide H2O2 to oxygen at several temperatures.
In separated black or brown solid phases, the presence of crystalline copper, cuprous oxide Cu2O or their mixture was confirmed. Irradiation of 0.01 mol.dm-3 solutions with low doses yields pure Cu2O, whereas at lower pH and lower copper concentration, copper particles are formed predominantly. SEM images showed that prepared particles are spherical in shape and have wide size range (50 - 500 nm in diameter, average size being cca 200 nm).
The stability of colloidal copper was investigated with respect to changes of absorption spectra and pH in the presence of air. Whereas the value of pH steadily increased with time, the absorbance changed non-monotonously – in the first stage, a rapid increase of absorbance in the range from 600 to 900 nm occurred, followed by long lag-phase (absorbance remained constant) and finally in the third stage, copper absorption spectrum reappeared, but slowly decreased.
(CTU in Prague)
Paper - Figures
Programming of material’s properties over extended time intervals via self-irradiation phenomena15m
We consider theoretically the possibility of programming the ageing processes in materials via the introduction of small quantities of unstable nuclei in a material’s structure. Ageing of materials is usually considered as a harmful and undesirable process, which limits the lifetime of many consumer products. In certain instances, however, changing of physico-chemical properties with time constitutes a part of material's functionality. Structure transformations owing to self-irradiation of materials by fission products of unstable isotopes constitute a special case of ageing processes. They are quasi-independent on environmental factors, such as heat, light, humidity, aggressive chemicals. A well-known example is metamictisation of zircon due to the decay of uranium and thorium atoms present in the mineral's crystal lattice.
In our work we suggest to exploit self-irradiation phenomena to programming of material's properties over extended time intervals. Using literature data on the action of ionizing radiation on different materials, we argue that incorporation of minuscule amounts of radio-active species, such as tritium, in the structure of certain polymers can lead to profound change of their physico-chemical characteristics over the times ranging from few months to several years. For instance, introducing tritium in the structure of polytetrafluoroethylene (PTFE) via substitution of a small fraction of the fluorine atoms can be used for programming radiolysis of the polymer and it´s self-destruction to a certain date. The date can be preset by concentration of tritium in the material, which is typically a few mg of tritium per kilogram of the polymer. Radio-active isotopes can be incorporated in the structure of conductive polymers, such as a blend of polyaniline (PANI) with poly (vinyl chloride) (PVC). Self-irradiation can lead to significant change of electronic properties of the material due to self-doping of PANI by hydrochloric acid released by the partner polymer upon irradiation. It is known that refractive index of materials (polymers, glasses) also can vary upon the action of ionizing radiations. Therefore it might be possible to program the value of the refractive index by radio-isotope engineering. Finally, self-irradiation can be applied to scheduled relaxation of internal mechanical stresses in materials.
Materials with time-programmed characteristics can find numerous applications in different fields of technology. For instance, polymer or inorganic semiconductors with programmed electronic properties can be used for the design of electronic devices which can be disabled or activated at a well-defined date. Due to miniaturisation of electronic circuits, tiny quantities of radio-active substances might be sufficient for this purposes.
 V. Luchnikov, "Time programming of material’s properties via self-irradiation phenomena", J Mater Sci (2009) 44:6294–6301
(Institut de Science des Matériaux de Mulhouse CNRS)
Radiation stability and extraction properties of thiacalixarenes15m
This study deals with the effects of irradiation on the stability and extraction properties of thiacalixarenes 1, the prospective liquid-liquid extractants for the extraction of actinides and lanthanides from aqueous solutions. Thiacalixarenes dissolved in various organic diluents were irradiated with 60Co γ rays or accelerated electrons with energy of 4.5 MeV. The absorbed doses ranged from 0 to 100 kGy. Possible effect of the presence of aqueous phase during irradiation was also investigated.
The extraction properties were studied in synergistic systems. The aqueous phase consisted of a solution of cosane (chloro-protected bis(1,2-dicarbollide) cobaltic acid) in 0.1 mol/L nitric acid; solutions of thiacalixarenes in nitrobenzen or 1,2-dichlorethane were used as the organic phase. Distribution ratios D for 152Eu and 241Am and their mutual separation factors were evaluated. The concentration of thiacalixarene in the irradiated samples was measured using HPLC and the activity of aqueous and organic phase was measured by γ spectrometer with HPGe detector.
The results confirmed previously published data 2 which showed a strong synergistic effect in the systems containing thiacalixarenes and cosanes. This effect depends on substituents at the lower and/or upper rim. It was demonstrated that the synergic effect is independent of the used type of cosane (chloro-, resp. bromo-protected bis(1,2-dicarbollide) cobaltic acid or bis(1,2-dicarbollide) cobaltic acid) and it strongly depends on the diluent used in the organic phase. The studied systems proved not to be very stable towards the radiation. After irradiation with the dose of 20 kGy, the distribution ratios dropped to one half for thicalixarene solutions in nitrobenzene; they dropped even to one tenth for dichlorethane solutions at the same dose.
This work was performed under the auspices of Czech Science Foundation grant GACR 104-07-1242 and Ministry of Education, Youth and Sports grant MSM 6840770020.
1. Lhoták P.: Eur. J. Org. Chem. 8, 1675 (2004).
2. Kyrš M.: J. Radioanal. Nucl.Chem, 245, 455 (2002).
(KJCH FJFI CVUT)
Comparison of radiation and thermal ageing simulation procedures for NPP cables15m
The accelerated radiation and thermal ageing of cables has a special importance in the type qualification test of NPP cables as it should provide for the cable ageing by an accelerated but real process of ageing, i.e., by the homogeneous oxidation of the cable polymeric materials. A comparison of three cable ageing techniques was performed on the representative NPP cables based on EVA and XLPE jacket and insulation materials. These techniques cover separated and combined radiation and thermal ageing under high dose rate (3 kGy/h) and low dose rate (5 Gy/h) in temperatures from 75 °C to 150 °C. The results of mechanical and physico - chemical properties are discussed and a recommendation for qualification test procedures are proposed.
(NRI Rez, plc)
Effects of dose and dose rate of γ radiation on catalytic activity of catalase15m
Catalytic activity of catalase from bovine liver was studied using experimental device designed for kinetic measurements of hydrogen peroxide decomposition at constant temperature and pressure. The kinetics of the reaction was evaluated by measuring the volume of released oxygen. The measurement was performed at four temperatures in the range of 25 – 45 °C. Rate constants of the reaction were estimated for all four temperatures. The values of apparent activation energy were obtained from their temperature dependence in Arrhenius coordinates. Reproducibility of both sample preparation and kinetics measurement was experimentally evaluated.
Solutions containing 1x10-3 - 5x10-6 g/mL of catalase in phosphate buffer were used for the study. γ irradiation was performed using 60Co radionuclide source Gammacell 220 with two different dose rates 7 and 70 Gy/h and doses ranging from 350 to 1000 Gy.
It was confirmed that the observed reaction of catalase with hydrogen peroxide is of the first order in the whole measured interval. Irradiation significantly decreases catalytic activity of catalase. However, apparent activation energy does not depend on the dose of radiation indicating that the mechanism of the hydrogen peroxide degradation does not significantly change with the dose, either.
(CTU in Prague, ČVUT jiný pracovní poměr)
Measurement of growth curves of microorganisms influenced by radiation15m
Relatively high attention is paid to various agents (e.g. chemical substances , hyperthermia and/or radiation [2,3]) influencing the growth of microorganisms. The influence of radiation on the microbial cells may be indicated not only by the survival curves, but also by the growth curves of irradiated and non-irradiated cultures.
The aim of the study is to point out to some aspects of the measurements of such growth curves. The Saccharomyces cerevisiae culture from variously irradiated inoculum in liquid peptone-glucose medium was used in all experiments. Irradiation of yeast cells in solution physiological (salt) was performed with γ-rays of 60Co in Gammacell 220 or with UV-irradiation using ultraviolet lamp UVH 1016-6 for various time periods. Various dose rates of both types of radiation were used. The absorbed doses reached some hundreds Gy for both γ and UV radiation. The growth curves were measured using the nephelometric data of yeast suspension in various time periods of growth. The results of many measurements showed that the slope of growth curves expressed relatively exactly the negative influence of irradiation when the standard and uniform method of evaluation was used. When the curves were fitted to the data points by the least-squares method, the average standard errors were found to be in the range from 0.6 to 0.8 % and from 0.2 to 0.5 % for γ- and UV- irradiation, respectively. The negative effect of irradiation depended monotonously and non-linearly on the applied dose of irradiation. Quantitatively different effects were found in the case of γ and UV irradiation.
1. Múčka V., Cabicar J.: Folia Microbiologica 14, 511 (1969)
2. Farhatazis, Rodgers M. A. J.: Radiation Chemistry. Principles and Applications. WCH Publishers, Inc., New York, 1987, 636 p.
3. Petin V. G., Kim J. K.: Radiat. Research 161, 56 (2004)
(CTU in Prague, ČVUT jiný pracovní poměr)
Radionuclides in the Environment, Radioecology 4Mirror Hall
Sorption behaviour of contaminants in soils: pH and humic acid effects on sorption of on CEC of clay soils and minerals, and the mobility of Cd, Cs, Ni and Sr.15m
The aim of this study is to use predictive modelling to understand and calculate the sorption behaviour of radionuclide contaminants in complex environments such as clay-based soils. The effects of Natural Organic Matter (NOM) on the Cation Exchange Capacities (CEC) of different characterised clay soils (St Bees & Mercia Mudstones, Boom clay & London clay) and their constituent clay minerals will be determined by ‘doping’ the samples with varying amounts of purified Humic Acid (not exceeding 15%) and measuring the changes in CEC.
This will be followed by an assessment of how NOM affects the mobility of radionuclides (Cadmium-109, Caesium-137, Nickel-63 & Strontium-85) through the materials using column and batch techniques. The experiments will be repeated with each of the constituent clay minerals (montmorillonite, kaolinite, illite, chlorite & bentonite) present in the soils using batch techniques, and the results obtained used to improve the understanding of the separate effects of each mineral on the overall sorption behaviour of the soils. This will lead to testing to determine if the Additivity Principle holds for these systems.
Radiometric Techniques & Inductively coupled plasma optical emission spectroscopy (ICP-OES) will be employed in the quantification of radionuclide speciation between the phases, and the samples will be characterised by SEM and XRD with the assistance of BGS.
Complexation of U(VI) with nitrogen and phosphorous containing ligands in aqueous solution15m
The long-term safety assessment of nuclear waste disposals requires detailed knowledge of the transport and interaction behavior of actinides within the technical, geotechnical and geological barriers. In the case of accidental release of radionuclides into the surrounding environment, their migration behavior can be effectively influenced by the ambient conditions like pH, temperature, ionic strength and especially the presence of inorganic and organic complexing ligands, e.g. bioligands like humic acids, amino acids or phospholipids. Due to their high complexing capacity towards metal ions these ligands may influence the mobility of actinides.
We studied the U(VI) complexation with nitrogen and phosphorous containing model ligands in order to simulate the functionalities of bioligands. The aim of this work is to determine the influence of various nitrogen and phosphorous containing functional groups on the U(VI) complexation and to evaluate their contribution in comparison to oxygen containing functional groups. As nitrogen containing ligands we used the biologically important substances anthranilic acid (AA) and nicotinic acid (NA). Furthermore, phenylphosphonic acid (PPA) was used as aromatic phosphorous containing ligand.
The complexation studies in aqueous solution were performed as a function of pH using time-resolved laser-induced fluorescence spectroscopy (TRLFS). All ligands show a complex formation with U(VI) under the given experimental conditions ([U(VI)] = 0.05 mM, [ligand] = 0 – 0.5 mM, pH 2-4, I = 0.1 M, T = 25°C). The binding of U(VI) by AA and NA takes place via the carboxylic group of the ligands. It can be concluded, that oxygen containing functional groups dominate the U(VI) complexation in the investigated pH range. The nitrogen functionalities of the ligands play only a subordinate role. AA forms a 1:1 complex, with a corresponding stability constant of log ß11 = 3.14 +/- 0.17 . The formation of 1:1 and 1:2 complexes was detected for the U(VI)-nicotinate system (log ß11 = 3.73 +/- 0.30, log ß12 = 7.46 +/- 0.17 ) as well as for the U(VI)-phenylphosphonate system (log ß11 = 3.58 +/- 0.17, log ß12 = 6.81 +/- 0.10). At high U(VI) concentrations (1 mM), a precipitation of the formed complexes was observed for the U(VI) complexation by AA and PPA. The precipitates were analyzed with FT-IR spectroscopy and X-ray diffraction. To study the influence of different functional groups on the complexation of actinides in different oxidation states, comparable complexation studies are performed with Am(III).
 B. Raditzky, K. Schmeide, S. Sachs, G. Geipel, G. Bernhard, Polyhedron (2009), doi:10.1016/j.poly.2009.08.010.
(Forschungszentrum Dresden-Rossendorf, Institute of Radiochemitry)
Vertical and horizontal distribution of <sup>137</sup>Cs in zone of Chernobyl contamination in Russia15m
Peculiarity of vertical migration of Cs-137 was investigated in zones of Chernobyl contamination (Bryanskaya, Orlovskaya, Tulskaya and Kaluzhskaya districts). Vertical distribution of Cs-137 on inviolate places characterizing by minimal penetration of peak of maximal concentration for the depth about 2-4 cm in dependence of type of soil and intensity of processes of byoturbation.
Practically all quantity of Cs-137 in inviolate soils accumulated in upper 0-15 cm. The waterlogged soils as well as acidic soils of the pine forests are exclusion of this rule, where Cs-137 на may migrate for the big depth. For example the sandy soils without feature of podzolic processes in the first 5 cm contain 97% quantity of radionuclide. In dernovo-podzols the first 5 cm contain only about 60% of Cs-137 and observed second peak of vertical distribution of Cs-137, related with accumulation of radionuclide in illuvial horizont.
Vertical distribution of Cs-137 in arable soils and adjacent slopes of dry valleys is formed greatly by processes of erosion and accumulation. There is observing the alternation zones of previously erosion and accumulation inside of the arable slope. On the flood planes of small rivers accumulation of radionuclide is discovered on the billow near the river-channel, peak of vertical distribution of Cs-137 placed on the 5-10 см depth. In marshi soils is usually discovered decreasing of Cs-137 in 0-25 cm depth relatively of soils of higher geomorphological positions, probably because of penetration of radionuclide in greater depth. But, in periodically wet conditions of flood plane depressions it can formed local spots of contamination in 5 times bigger then soils of adjacent dry hills.
(Institute of global climate and ecology)
The sorption processes of Np(V) and U(VI) onto metal oxide phases. The formation of sorption complexes and mechanistic aspects studied by in situ ATR FT-IR spectroscopy15m
The migration behaviour of actinide ions in the geosphere is generally influenced by sorption processes in aqueous media. These processes occurring at solid/liquid interfaces can be monitored by in situ Attenuated Total Reflection Fourier-transform Infrared (ATR FT-IR) spectroscopy providing structural information on a molecular level.
In this work, the sorption of neptunium(V) onto metal oxides was investigated for the first time by ATR FT-IR spectroscopy. From the Np(V) sorption studies on the metal oxides, stable surface species of NpO2+ are derived. The type of the sorbed species can be elucidated by a spectral shift (~ 30 cm−1) to lower wavenumbers of the antisymmetric stretching vibration υ3(NpO2+) compared to the aqueous species suggesting an inner-sphere complexation. Outer-sphere complexation is found to play a minor role due to the pH independence of the sorption species throughout the pH range 4 – 7.6. The comparative spectroscopic experiments of Np(V) sorption onto TiO2, SiO2 and ZnO indicate structurally similar bidentate surface complexes.
A detailed insight into the molecular mechanisms occurring during the formation of ternary actinide complexes at the solid/liquid interface is provided upon formation of uranyl carbonato complexes on ferrihydrite (Fh). The influence of the presence of atmospheric carbon dioxide during the sorption processes of the actinide ions was studied by sorption experiments which were carried out under inert gas conditions and in an ambient atmosphere. From the results, the formation of bidentate [Fh•••UO2•••O2CO] complexes can be derived under mildly acid conditions which is in agreement from recent EXAFS results obtained from batch samples.
Furthermore, experiments with 13C labelled carbonate provide an unequivocal assignment of the spectral features reflecting the structural alterations of the carbonate ions upon sorption of uranyl cations onto Fh. From these assignments, the formation of the ternary uranyl complexes can be described at a molecular level.
 Lefèvre, G. (2004) Adv. Colloid Interface Sci. 107, 109-123.
 Müller, K. et al. (2009) Environ. Sci. Technol., in press.
 Rossberg, A. et al. (2009) Environ. Sci. Technol. 43, 1400-1406.
(Forschungszentrum Dresden-Rossendorf, Institute of Radiochemistry)
Impact of U-mill tailings of the former uranium mine at Žirovski Vrh (Slovenia) on radionuclide accumulation by wetland plants15m
Transfer of radionuclides into the environment is a common phenomenon and due to its potential harmful effect of particular scientific interest in the vicinity of uranium mines. Radionuclides, especially uranium and thorium decay products are discharged with U-mill tailings into the soil and water and consequently into vegetation where they accumulate. Radionuclide soil-to plant transfer was observed in many studies. Uranium mine at Žirovski Vrh in Slovenia, which operated from 1985-1990, processed about 600,000 tons of U-ore. U-milling and mining tailings were deposited at the Boršt and Jazbec sites. Plants that grow in the vicinity of U-mill tailings may accumulate radionuclides in their tissues and thus represent a possible transfer of radionuclides into the food chain. This are so called metal-accumulating plants, that developed metal resistance mechanism and may grow on metal-contaminated or metalliferous soil. Plants, such us Marsh marigold (Caltha palustris), soft rush (Juncus effusus) and common reed (Phragmites australis) are known as accumulator plants, because they accumulate toxic metals in their above-ground tissues. Other plants, especially grasses may also grow on metal contaminated soils, but do not accumulate metals. Preliminary results of radionuclide accumulation by such plants growing in the contaminated area are presented. A common reed, that was grown on the uranium-mill tailings accumulated 0,01 Bq/g d.w. and 0,002 Bq/g d.w. of uranium in leaves and stems, respectively. In contribution, activity concentrations of other nuclides from uranium and thorium decay chains in other plants are also presented and discussed.
(Jožef Stefan Institute)
Transport of <sup>125</sup>I<sup>-</sup>, <sup>137</sup>Cs<sup>+</sup> and <sup>85</sup>Sr<sup>2+</sup> in granitoidic rocks and soil15m
Transport of 125I-, 137Cs+ and 85Sr2+ radionuclides in crushed granitoidic rocks and homogenized soil was studied. Two simple methods for calculation of transport parameters of these radionuclides in flow column experiments with groundwater (GW) as transport medium have been described. The first method is based on the assumption of a reversible linear sorption of reactive solutes (radionuclides) on solid phase (with constant distribution, Kd, and retardation, Rexp, coefficients), whereas the second one is based on the assumption of a reversible non-linear sorption (characterized with non-linear sorption isotherm, i.e. with non-constant Kd and Rexp). Both methods use the experimental breakthrough curves (BTCs), which are constructed using the measured activities at the outlet from the column. The BTCs are fitted with the integrated form of the simple 1-D advection-dispersion equation (ADE) expressed analytically for pulse application of radiotracer to the liquid phase (GW) before entering into columns. In case of the first method, the integrated form of ADE is modified by two correction coefficients, namely, the peak position and peak height coefficients by means of which the very good agreement between experimental and calculated data is usually obtained. The second method is more sophisticated because not only the calculation of the values of retardation coefficients changing during transport is needed, but also the Freundlich equation parameters of non-linear isotherm have to be sought. Both methods were tested in the evaluation of the transport parameters of a given radionuclides in beds of diorite, gabbro, granite and tonalite granitoides and clayey loamy sandy soils. The results of two different approaches have been compared.
(Nuclear Research Institute Řež plc)
New amino acid synthons for preparation of [<sup>18</sup>F]FDOPA and α-[<sup>11</sup>C]methyl amino acids for positron emission tomography30m
PET diagnostics using radiolabelled amino acids is an emerging branch of nuclear medicine. This includes visualisation and grading of brain, neuroendocrine and prostata tumours, measurement of protein synthesis rate in tumour cells, quantitative in vivo measurement of dopamine and serotonin metabolism in brain. Development of clinical applications is limited by complexicity of robotic devices necessary for multi-step preparation of the enantiomerically pure amino acids. Robust and reliable approaches not requiring sophisticated separation of radiolabelled intermediates have to be created for everyday clinical routine. Nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide (BPB) and α-amino acids were developed as artificial analogues of pyridoxal 5'-phosphate (PLP)-dependent enzymes for asymmetric synthesis of amino acids. Current approach using BPB in nickel(II) complex of its Schiff base with glycine allows easy preparation of O-(2'-[18F]ﬂuoroethyl)-L-tyrosine ([18F]FET) with 94-97% e. e. with no need for separation of diastereomers of alkylated complexes. Preparation of 6-[18F]FDOPA using the same starting nickel complex gives only 77±5% e. e. without separation of diastereomers of alkylated complexes while the same preparation of α-[11C]DOPA leads to 92-99% e. e. Preparation of α-methyl DOPA or α-methyltyrosine labelled with carbon-11 or fluorine-18 requires formation of quaternary chiral centre, stereochemistry of which is controlled kinetically. Kinetic control is much less efficient then thermodynamic one, thus diastereomeric excess of complexes of α-methyl amino acids is inferior. Enhancement of stereodivergent power in both thermodynamically and kinetically controlled alkylation reaction is the biggest priority in development of new metallocomplex tools for the preparation of PET amino acids.
In this presentation the evaluation of new amino acids synthons bearing C2-symmetric benzyl groups with electron-donating and electron-withdrawing substituents will be described. Compatibility of amino acid side chains protective groups will be assessed in relation to the reaction conditions used for preparation of the complexes.
(Department of Information Systems, Faculty of Health and Social Studies, University of South Bohemia)
Optimisation of the radiosynthesis of 4-[<sup>18</sup>F]fluoromethyl-L-phenylalanine and [<sup>18</sup>F]FET via a same Scintomics automated synthesis hotboxthree module.15m
It was recently reported that the success of O-(2’-[18F]fluoroethyl)-L-tyrosine ([18F]FET) as PET tracer is limited to brain, head and neck tumours and that there is still a need for more potent amino acid analogues for peripheral tumour imaging. We hereby report on the radiosynthesis of a new tracer 2-Amino-3-(4-[18F]fluoromethyl-phenyl)-propionic acid (4-[18F]FMP), taken up in tumours by the LAT1 amino acid transport system, performed with a customised Scintomics automatic synthesis hotboxthree module. The labelling reaction is based on Br for [18F] aliphatic nucleophilic exchange on 3-(4-bromomethyl-phenyl)-2-L-tert-butoxycarbonyl- amino-propionic acid tert-butyl ester. The critical point in the synthesis pathways was the deprotection of the NCA 3-(4-[18F]fluoromethyl-phenyl)-2-L-tert-butoxycarbonyl- amino-propionic acid tert-butyl ester obtained after labeling due to the highly activated 18F-benzyl group and the presence of a strong acid (trifluoroacetic acid). HPLC purification and mini-column trapping followed by appropriate recovery allowed to obtain NCA 4-[18F]FMP in a overall yield of 30% and with a radiochemical purity of > 99 %. This tracer was found to be stable in its radiopharmaceutical formulation for at least a working day, even at high radioactivity concentrations. Additionally, for a comparative clinical study, [18F]FET was synthesized applying the in literature described Tosyl [18F] aliphatic nucleophilic exchange followed by deprotection and HPLC separation using the same module set-up. Here a 40% overall yield is obtained with a radiochemical purity > 99%.
The described automated radiosynthesis module allows the high yield production of these two amino acid analogues with minor alternations to the parameter settings of the automated system, although two different labeling reactions are performed, rendering this unit versatile for both research and clinical practice.
Heterocyclic labelled derivatives of Betulinines15m
The lupane type compounds have played a singular role among pentacyclic cytotoxic triterpenoids from the beginning of 21st century, mainly for their various biological activities1, which include antineoplastic, antiviral, anti-inflammatory, antimicrobial activities and also hepato- and cardioprotective effects. The derivatives of betulin and betulinic acid have been tested on various tumor cells lines for their activity2. The heterogeneous family of triterpenoids, including highly oxidized lupane, des-E-lupane, oleanane and others derivatives, posses a significant cytotoxic and antiviral activity and was named Betulinines3-6. Betulinines have proved multispectral cytotoxic activity on the panel of 10 cell tumor lines of different histogenetical origin, including multidrug resistance.
Our research group has three main pathways of interest. The first is a chemical path, which is focused on synthesis of new derivatives based on SARS6. The second one is a radiochemical path, which is specialized in synthesis of selectively labelled compounds of the most cytotoxic active compounds7. Finally, it is a biological path, which tests biological activities of synthesized compounds, investigates of mechanism of action and formulates of SARS conclusions6.
During the past years have been synthesized several labelled derivatives, that have been used for investigation of mechanism, labelled by deuterium, tritium, carbon-13, carbon-14 and nitrogen-15. Recent interest of our research is synthesis of heterocyclic labelled derivatives of heterobetulinic, morolic and betulinic acid. Mentioned compound will be studied for their biological activities, especially for antitumor and anti-HIV in cooperation with LEM in Olomouc.
1. Dzubak P. ET AL.: Nat. Prod. Rep. 23 , 394 (2006).
2. Pisha E. et al.: Nat. Med. 1, 1046 (1995).
3. Hajduch M., Sarek J.: Triterpenoid derivatives. PCT Int. Patent Appl. WO0190136, 23 May 2001.
4. Hajduch M., and Sarek J.: Triterpenoid derivatives. PCT Int. Patent Appl. WO0190046, 23 May 2001.
5. Hajduch M., Sarek J.: Triterpenoid derivatives. PCT Int. Patent Appl. WO0190096, 23 May 2001.
6. Sarek J. et al.: J. Med. Chem. 46 , 5402 (2003).
7. Vlk M., Sarek J., Hajduch M. and Elbert T.: Chem. listy 102, 1079 (2008).
(Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, CTU Prague)
Preparation of [<sup>48</sup>V]TiO<sub>2</sub> labelled nanoparticles for biokinetics studies.15m
Engineered nanoparticles are of current interest in many applications (e.g. industry, medicine, energy). As they are produced in ever higher quantities, the need to assess their biokinetics and toxicity becomes more and more important. The aim of this study was to prepare stable, radiolabelled bioavailable TiO2 nanoparticles to assess their in vivo biokinetics. The preparation of [48V]TiO2 nanoparticles by direct proton irradiation is described.
Irradiations were performed on the Scanditronix MC-40 cyclotron at JRC Ispra, Italy with a 5 μA proton beam of 23.5 MeV energy. After 16 hours irradiation, a commercial sample of TiO2 (ST-01, Ishihara Corp. Japan) yielded approx. 40 MBq of 48V activity at EOB. Half of the irradiated material was processed two weeks after EOB to size-select and purify the labelled nanoparticles from free 48V by centrifugation and filtration. This yielded 855 kBq of final suspension of fine [48V]TiO2 labeled nanoparticles (Z average = 105 nm) without free 48V. In vivo results in a rat model indicated good 48V label stability with less than 1% of the administered dose eliminated by renal excretion, compared to ionic 48V with approximately 50% renal clearance.
Acknowledgement: This work is funded by the European Commission’s 7th Framework Programme, ”NeuroNano” project (contract NMP4-SL-2008-214547)
The influence of the side groups of the BTP and BTBP type ligands on liquid-liquid extraction of actinides and lanthanides15m
Fossil fuels are no longer a choice for energy production, both because of their diminishing availability and the bi-products of their combustion processes. A possibility to replace the fossil fuels would be utilization of nuclear power. No green-house gases are produced, but as any industry, it generates wastes.
A proper plan for reusing valuable nuclides, both by preparing another kind of fuel or by transmutation, which, besides transforming the long-lived nuclides into short-lived ones, generates energy, seem to be P&T (partitioning and transmutation).
The partitioning is the process of separation nuclides from the rest of the waste and involves a separation process which utilize an organic solvent containing one or several molecules and a diluent for extraction purposes.
Among the last extractant families developed in Europe, the 2,6-di(5,6-diethyl-1,2,4 triazin-3 yl)pyridine (BTP) and 6,6’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]triazin-3-yl)-[2,2’]bipyridine (BTBP) were/are the most promising molecules for an eventual industrial application.
The present work focuses on several aspects insufficiently studied before and concerning the influence of the side groups attached to the "core" of the moelcule, for both BTPs and BTBPs.
The importance of the diluents regarding both the extraction capabilities of the formed system and the role of the diluents in protecting the molecule against radiolysis without adding a scavenging molecule will be very briefly discussed. However this part will not be further developed here.
The importance of the side groups added to the molecule first to facilitate dissolution, easing the phase transfer and thus enhancing the extraction capabilities and the role the side groups, in protecting the molecule against the radiolysis will be discussed.
(Chalmers University of Technology)
Solvent extraction studies for the separation of radioarsenic, radiogermanium and radiogallium15m
Solvent extraction techniques were developed to separate As-72 from bulk amounts of proton-irradiated germanium dioxide targets, Ge-68 from proton-irradiated gallium(III) oxide targets and Ga-68 from parent Ge-68.
Several methods have been reported to isolate arsenic radionuclides from irradiated Ge and germanium dioxide targets [1,2]. In this work the germanium dioxide target, irradiated with 17 MeV protons, was dissolved in either HCl or KOH. Then the ratio of As(III) to As(V) was determined via thin layer chromatography using Si-60 phase plate as a stationary phase and a mixture of sodium bitartrate/methanol in the ratio of 3:1 as the mobile phase. Our separation method utilizes the observation that arsenic (III) can be extracted selectively and quantitatively by cyclohexane from hydrochloric acid solution containing alkali iodide . The influence of concentrations of different acids and of KI as well as the effect of various organic solvents was investigated. Optimally, the extraction of As(III) into cyclohexane occurred with 4.75 M HCl and 0.5 M KI, and its back-extraction into the aqueous phase with water containing 0.1 % hydrogen peroxide. The overall radiochemical yield of the radioarsenic separation was about 95±2 %. The method was used in the separation of high purity As-72, a potentially useful positron emitter, formed via the Ge-72 (p,n)-reaction.
An optimised method of separation of the radionuclide Ge-69, used as a tracer in gallium /germanium separation studies, was worked out. The gallium (III) oxide target, irradiated with 17 MeV protons, was dissolved in 8 M sulphuric acid and used as a stock solution. To an aliquot HCl was added and its concentration adjusted to 0.4 M in order to transfer germanium to the chloride form. With this the extraction of radiogermanium using toluene was then studied at varying concentrations of H2SO4. From a solution of 8 M sulphuric acid and 0.4 M HCl the extraction was maximum. Using the optimised separation, the radionuclide Ge-68, formed via the Ga-69 (p,2n)-reaction, was separated from a gallium (III) oxide target irradiated with 45 MeV protons.
Further on, the separation of Ga-68 from the parent Ge-68 was investigated. The method is based on anion exchange solvent extraction using Aliquat 336 in xylene from hydrochloric acid . Aliquat 336 in xylene has been used for the first time for separations involving radiogallium and radiogermanium. Optimisation studies were related to the influence of HCl concentration and different solvents. The solvent extraction using Aliquat 336 in xylene led to a high separation yield of 68Ga from its parent Ge-68. The time of separation was short with about 20 min, the contamination from Ge-68 was less than 0.1 % and the final product was obtained in 0.5 M KOH.
 S. Mirzadeh and R. M. Lambrecht, J. Radioanal. Chem., 202 (1996) 7-102.
 M. Jennewein, S. M. Qaim, A. Hermanne, et. al, Appl. Rad. Isot., 63 (2005) 343-351.
 S. K. Sahoo, Bull. Chem. Soc. Jpn., 64 (1991) 2484-2487.
(Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany)
Novel solid-phase extractants for radionuclide preconcentration15m
Preconcentration of radionuclides is a necessary stage for their accurate determination in aqueous natural and technological solutions. Sorption methods are the most perspective for selective recovery and separation of radionuclides from other elements. Various sorption materials containing complexing groups have been widely applied due to their selectivity and high degree of recovery. It is especially important for radionuclide preconcentration from high salinity nitric acid solutions generated under the reprocessing of spent nuclear materials.
The solid-phase extractants have gained considerable attention for preconcentration of trace elements. Special interest is given to the solid-phase extractants prepared by non-covalent immobilization of ligands on the surface of solid supports. For actinide and lanthanide preconcentration some organophosphorus and other ligands (tri-n-butylphosphate, carbamoylmethylphosphine oxide, malonamides, amines, macrocyclic compounds, etc.) have been widely used. These reagents are usually immobilized on silica-based matrices, polystyrene and polyacrylate polymers and other supports.
In the present work we used ionic liquids and various ligands as reagents for immobilization and the most perspective solid supports to prepare the novel solid-phase extractants designed for radionuclide preconcentration.
The ability of ionic liquids to be kept on solid surfaces and to reveal ion-exchange and complexing properties makes possible the synthesis of novel type solid-phase extractants. We prepared the solid-phase extractants by the non-covalent immobilization of tetraalkyl phosphonium and 1-alkyl-3-methyl imidazolium ionic liquids with different anions and studied their sorption properties. The matrices with large surface and high sorption ability were chosen as supports: multi-walled carbon nanotubes, highly cross-linked polystyrene, Amberlite XAD-7 and polyacrylonitrile fiber. The conditions of ionic liquid immobilization and radionuclide recovery were determined. The application of prepared solid-phase extractants for preconcentration of actinides, rare earth elements and radiopalladium from 1-3M nitric acid solutions was demonstrated.
Special attention was being paid to the use of carbon nanotubes as a support for solid-phase extractant preparation. Carbon nanotubes have come under intense multidisciplinary study due to their unique physical and chemical properties, which make them attractive for myriad uses including radiochemistry. The features of nanostructure and large surface ensure high sorption ability of carbon nanotubes and the possibility for their modification. We prepared the solid-phase extractants on the base of multi-walled carbon nanotubes “Taunit”® (Russia) modified with ionic liquids and various ligands. Experimental data have shown high efficiency of the novel solid-phase extractants for radionuclide preconcentration from nitric acid solutions.
The work was supported by the Russian Foundation for Basic Research (project 08-03-00766).
1. Myasoedova G. V., Molochnikova N. P., Mokhodoeva O. B., Myasoedov B. F.: Anal. Sci. 24, 1351 (2008).
(Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences)
Bentonite stability and migration behavior of some critical radionuclides15m
The contribution is focused on geotechnical, chemical, geochemical and mineralogical research of bentonite stability with the aim to determine the effect of saturation medium composition and loading by heat on bentonite stability. The main part the research is directed to the experimental results of bentonite and bentonite leachate samples obtained for the bentonite interaction under laboratory or in situ experiments.
The markedly different values of Na+, K+, Ca2+, Mg2+ and SO42- ion concentrations are caused by the mineralogical transformation and interaction of the original bentonite material with synthetic granitic water.
Bentonite is included in buffer and backfill materials in most high-level waste repository concepts. Its low hydraulic conductivity, micro-porous structure, good sorption properties and plasticity make this material an effective barrier – protecting the canister and restricting the movement of radionuclides released from the waste packages after canister failure.
The effect of the variable aqueous phase composition on bentonite stability using Ca-Mg and Na-Ca bentonites for the experiments was studied. The synthetic granitic waters with the higher concentration of the K+ and Mg2+ cations were applied for the study of bentonite stability. These investigation were carried out for the 12 months under the laboratory and temperature increase conditions (95 - 100°C). The mineralogical transformation and characterization of the solid phase by RTG diffraction, infrared spectroscopy and cation exchange capacity measurement were evaluated after the termination of these experiments. These mixtures were simultaneously applied for the sorption study of the selected radionuclides (134Cs, 125I and 99TcO4-) with the aim to evaluate the changes of sorption behaviour as the result of bentonite with synthetic granitic water interaction.
The geochemical software tool Geochemist’s Workbench calculated the simple thermodynamic model of bentonite transformation during bentonite with synthetic waters interaction. It was confirmed that smectites are transformed to more stable silicates phases, such as illite/smectite mixed layers, illite. The kinetics of the smectite to illite reactions strongly depends on temperature, time and K+ porewater concentrations.
Radionuclides of 99Tc and 129I may exist in the various oxidation states in the dependence of the redox conditions of the aqueous environment. Technetium exists in oxidation states from +7 to -1. In natural environments, the most stable oxidation states of technetium are +7 and +4 under oxidizing and reducing conditions, respectively. The -1, +5, and molecular I2 [I20(aq)] oxidation states are those most relevant for iodine in environmental systems. Iodine usually exists in fresh water in the -1 oxidation state as iodide (I-), in alkaline and marine environments, iodine usually exists in the +5 oxidation state as iodate (IO3-).
(Institute of Chemical Technology)
Speciation of curium(III) and europium(III) in human urine samples15m
Due to their radiation and heavy metal properties, radionuclides represent a serious health risk to humans in case of incorporation. To understand their toxicity, transport, deposition and elimination in the human organism, it is therefore crucial to elucidate their chemical behavior and properties on a molecular level. For trivalent actinides originating from nuclear power plants knowledge about their metabolism is very limited. In case of incorporation, they tend to accumulate in liver and skeleton and are excreted to maximum 10 – 20 % within the first week. Nevertheless this excretion occurs mainly through the kidneys, which are known to be particularly radiation sensitive.
To address the lack of knowledge, we studied the speciation of curium (as a representative of trivalent actinides) and europium (as the lanthanide analogue) in human urine and their complexation with single constituents. Since both of these heavy metals exhibit unique fluorescence properties, time-resolved laser-induced fluorescence spectroscopy (TRLFS) is an adequate tool for this purpose.
Fresh 24-hours-urine samples were collected from healthy volunteers and analyzed within few days. The inorganic composition of all samples was determined using mass spectrometry with inductive coupled plasma (ICP-MS) and ion chromatography (IC). Then all samples were spiked in vitro with curium or europium and single as well as time-resolved laser-induced fluorescence spectra were measured. We analyzed at least 10 different urine samples and were able to divide all samples into two different groups according to their fluorescence spectra.
We found that all samples with a pH below 5.6 and all samples with a pH above 6.0 each exhibit strikingly similar spectra. Compared to each other the spectra of both groups are very different and therefore easy to distinguish. Furthermore the lifetime of the metals in samples with higher pH is substantially longer than in samples with lower pH. ICP-MS and IC analysis revealed that the inorganic composition of samples which exhibit the same fluorescence spectra can vary broadly within magnitudes. Therefore the most important factor influencing the speciation of metals in human urine does not seem to be the composition but was determined to be the pH.
To identify the dominating species we also recorded the fluorescence spectra of both metals in electrolyte solution containing all inorganic but no organic components of urine. Furthermore we studied the complexation of both metals with urea and citric acid as main organic urine constituents. Comparing the measured spectra and lifetimes with this reference data, we found that at lower pH a complex citric acid species dominates the speciation of both metals while at higher pH the spectra where identical to those in electrolyte solution ruling out any involvement of organic ligands. The exact nature of this inorganic metal species has yet to be clarified.
(Forschungszentrum Dresden-Rossendorf, Institute of Radiochemistry)
Determination of <sup>237</sup>Np, <sup>93</sup>Zr and other long-lived radionuclides in medium- and low-level radioactive waste samples15m
The majority of long-lived radionuclides produced in the nuclear fuel cycle can be regarded as “difficult to determine nuclides” due to the low activities and/or the absence of gamma-radiations of medium or high energies in the decay schemes. Most isotopes of actinoides are alpha-emitters, Sr-90 (fission product) and Zr-93 (activation product) emit almost exclusively beta-particles, Nb-93m (activation product) decays by isomer transition or electron capture and emits only X-rays, Nb-94 (activation product) emits low intensity gamma-radiation due to its low activity.
Chemical separation is needed before the nuclear measurement of all the isotopes mentioned above.
A combined radiochemical separation method had been developed that enables the simultaneous determination of Th-230, Th-232, U-234, U-235, U-238, Pu-239-240, Pu-238, Am-241, Cm-242, Cm-244, Sr-89, Sr-90, Nb-93m and Nb-94.
Recently, this method has been extended for determination of Np-237 and Zr-93.
The main steps of the method are addition of tracers and carriers, sample destruction, co-precipitation on iron(II) hydroxide and calcium oxalate, separation by extraction chromatography using supported dipentyl-pentylphosphonate (UTEVA), supported N,N-octylphenyl-di-i-butylcarbamoylmethyl phosphine oxide (TRU) and supported bis-(t-butylcyclohexano)-crown(18,6)ether (Sr.Resin), separation on anion exchange resin, alpha- and beta-source preparation, alpha spectrometry, liquid scintillation counting (LSC), gamma spectrometry, measurement by inductively coupled plasma mass spectrometry (ICP-MS).
Np-237 and Zr-93 are pre-concentrated by co-precipitation on iron(II) hydroxide and zirconium oxide, and separated by extraction chromatography using UTEVA.
The key parameter of the method is the adjustment of the oxidation state of the actinoides before adding the sample onto the UTEVA column.
This can be done using many redoxi agents (for example potassium bromate, sodium nitrite or ammonium peroxo disulfate).
Highest yields were achieved when ammonium peroxo disulfate was used with silver nitrate as catalyst.
As even traces of isotopes with mass number near 237 or 93 cause considerable interferences during ICP-MS detection, a purification step by extraction chromatography was inserted.
It was determined by model experiments, that even a small amount of fluoride anions inhibits the retention of Zr on UTEVA, but this problem can be eliminated by addition of boric acid.
Analyzing real samples (evaporation concentrates of a nuclear power plant) 66-97% and 31-66% chemical yields were achieved for Np and Zr, respectively.
(BME NTI (Budapest University of Technology and Economics, Institute of Nuclear Techniques))
Nuclear Methods in Medicine, Radiopharmaceuticals and Diagnostics, Labelled Compounds 2Mirror
The use of radionuclides as potential therapeutic radiopharmaceuticals is increasingly investigated. An important aspect is the delivery of the radionuclide to the target, i.e. the radionuclide is not lost from the chelating agent. For in vivo generators it is not only the log K of complexation between the metal ion and the chelator that is important but whether the daughter radionuclide stays inside the chelator after decay of the parent radionuclide. In our previous work  we showed that the classical recoil effect only is applicable for decays with a Q value higher than 0.6 MeV (in the atomic mass range around 100). However Rosch et al  published result for Nd-140/Pr-140 (Q = 0.222 MeV) which indicated that >95% of the daughter (Pr-140) was lost by a DOTA chelator upon decay of Nd-140. This was explained to be due to a “post-effect” by the authors.
Their experiment was repeated with the Dy-166/Ho-166 potential in vivo generator to confirm that our calculations were correct. It was found that indeed some of the daughter (Ho-166) was liberated from the DOTA chelator, therefore indicating that the “post effect” does exist in contrast to our recoil calculations. Upon further investigation we determined that one should not only consider recoil energy levels but also the mode of decay (decay of the parent nuclide and the height of excitation states of the daughter nucleus). If decay takes place via electron capture (EC), Auger electrons are emitted resulting in a daughter radionuclide with a very high oxidation state due to the loss of these electrons from the electron shells. From the well known described biological effects of I-125  which decays to (Te-125)21+ one knows that chemical bonds in the vicinity of the decay are broken. It is therefore postulated that the EC decay of Nd-140/Pr-140 results in a Nd-140 daughter that destroys the DOTA chelate and is therefore released from this chelator. In the case of Dy-166/Ho-166 (Q = 0.486) the decay mode is via β- decay (which according to our recoil calculations is not strong enough to break the bond with the chelator) followed by dissipation of excitation energy of the excited state of the formed daughter nuclide via a branched decay - γ radiation and conversion electron process. The percentage of decay via the conversion electron process was found to match the percentage of the amount of Ho-166 that was measured to be released from the DOTA chelator in our experiment.
It is therefore concluded that the recoil effect below 0.6 MeV is not sufficient to rule out release of the daughter nuclide from chelators but one needs to consider the mode of decay as well. This knowledge has important implications for the design of future radiopharmaceuticals.
 Z. Szucs, J. Van Rooyen, J.R. Zeevaart. Applied Radiation and Isotopes. 2009, 67, 1401-1404
 K.P. Zhernosekov, DFiloofov, S.M. Qaim, F Rosch. Radiochim. Acta, 2007, 95, 319-327
 K.S.R. Sastry. Report no. 1 of AAPM Nuclear Medicine Task group No. 6. Med. Phys. 1992, 19, 1361-1383
Radiometric enzyme assays are based on the conversion of radio-labeled substrates to labeled products, and on the measurement of radioactivity of either products or residual substrate after their quantitative separation. In the present studies, we aimed to establish valid assay conditions for radiometric determination of the activities of several enzymes, which are involved in the metabolism of thyroid hormones (TH): Thyroid peroxidase (TPO), the key enzyme in the biosynthesis of TH in the thyroid gland, and uridinediphospho-glucuronyl-transferase (UDPGT) and iodothyronine sulfotransferases (ST), the enzymes responsible for biotransformations of TH in peripheral tissues. Further, with the aid of such developed assays, we attempted to follow the effects of some exogenous substances - bromide and perchlorate ions as supposed goitrogenic agents, and an antidepressant drug fluoxetine (Prozac) - on the metabolism of TH in the rat.
The procedure of the radiometric assay for TPO in vitro was based on the ability of TPO to oxidize [131I]-iodide in the presence of H2O2, generated in situ by glucose oxidase, and to catalyze subsequent iodination of specific tyrosyl residues in the added thyroglobulin. The measure of TPO activity in microsomal fractions of the thyroids was the amount of radio-iodine incorporated into thyroglobulin. This was determined either after TLC separation of the incubated samples, or simply after precipitation of radio-labeled protein and measurement of 131I radioactivity in separated fractions.
In the radiometric assay for UDPGT in rat liver microsomes, the rate of conjugation of phenolic group of L-3,3',5'-[125I]-triiodothyronine ([125I]-rT3) with glucuronic acid, which was catalyzed by UDPGT was measured. Reaction mixtures, containing uridinediphospho-glucuronic acid, the substrate [125I]-rT3 and samples of microsomes, were analyzed after the incubation by chromatography on micro-columns of lipophilic Sephadex LH-20.
The basis for radiometric determination of ST activity in liver cytosolic fractions was the transfer of sulfonate moiety from the "active sulfate", 3'-phosphoadenosine 5'-phosphosulfate, to the substrate [125I]-rT3. The extent of conversion was determined after the separation of the sulfated product from the unmodified [125I]-rT3, again by Sephadex LH-20 chromatography.
With the use of the described radiometric assay for TPO, we found that the influence of exogenous bromide on the TPO activity in the rat thyroids was biphasic, with regard to the extent of bromide intake in the animals. Administration of fluoxetine alone caused a significant (about 2-fold) increase in UDPGT activity. In contrast, the radiometric determination of ST did not demonstrate any significant effects of the application to the rats of fluoxetine alone, or together with T3, on the induction of these enzyme activities.
Acknowledgments: This work was supported by the Academy of Sciences of the Czech Republic (Research project No. AV0Z50110509), by the Ministry of Education of the Czech Republic (Research project No. MSM0021622413) and by the Czech Science Foundation (Grant No. 304/08/0256).
(Dept. of Radiometry, Inst. of Physiolgy, ASCR Prague; and Inst. of Biochemistry, Masaryk Univ. Brno, Czech Rep.)
The synthesis, labeling and careful spectroscopic investigation of meta-iodo-benzyl guanidin has been performed. As result of ESI MS and single crystal X-ray diffraction the corect structure is meta-iodo-benzyl guanidine hemisulfate hemihydrate (2 MIBG. H2SO4.H2O).
(Faculty of Science, Charles University)
Poster Appetisers - Chemistry of Nucl. Fuel Cycle, Radiochem. Problems in Nucl. Waste Manag.Red Hall
Probability for type I errors in γ-ray spectrometric measurements of drinking water samples15m
In gamma-ray spectrometry the activities are calculated from areas of the peaks appearing in the spectrum. If a peak used in the activity calculations appears in the spectrometer background its count rate must be corrected for the background contribution. The significance of this correction becomes essential in spectral analyzes where activities close to the minimum detectable activity need to be determined.
The presence of radionuclei in the sample, that contribute to the spectrometer background, can only be detected from the excess of the count rate in the peaks over their background level. Therefore, the radionuclei can be categorized in two groups:
- Radionuclei that do not appear in the spectrometer background. The probability of the wrong detection of these radionuclides is given by the sensitivity at which the peak-search algorithm recognizes the background fluctuations as peaks.
- Radionuclei that appear in the spectrometer background. Here, a radionucleus is identified if the count rate in its peaks exceeds the background level. In this case the probability of a false detection is given by a criterion, on the basis of which the number and the significance of the peaks where the excess occurred decide on the presence of the radionucleus in the sample.
It follows that for the second group, the minimum detectable activity that can be attained depends on the accuracy with which the background is determined and on its stability over time. It should be noted that if the contribution from the sample to a peak area is small as compared to the contribution of the background, there exist an equal probability that the result of the background subtraction is larger than zero or smaller than zero.
To check the rate of falsely detected radionuclides (type I errors) an analysis was made in which the background spectra were treated as sample spectra. From this it is known that in the analysis of these spectra all the detections of radionuclides are false.
The spectral analyzes were preformed with Canberra’s GENE ESP spectroscopy system. The nuclide library that was used is composed of radionuclei usually found in the environment and radionuclei that occur in the effluents from nuclear power reactors and hospitals. In the case of multi-gamma-ray emitters, the nuclide library includes the most abundant gamma-rays as well as the gamma-rays that cause interferences with other radionuclides, in order to correct the activities for these interferences. The criterion that determines whether a radionucleus has been detected is based on a comparison of the sum of the emission probabilities of the gamma-rays, where the count rate in the spectrum exceeds its background value and the sum of the emission probabilities for all the gamma-rays of this radionucleus that are included in the library. If the ratio of both sums exceeds a predetermined value, the gamma-ray emitter is considered as being present in the sample.
In the presentation the rates of type 1 errors will be presented for single gamma-ray emitters and multi gamma-ray emitters. The empirical minimum detectable activities for water samples for these radionuclei will be given.
(Jožef Stefan Institute, Ljubljana, Slovenia)
An inter-calibration campaign using various selected Pu spike isotopic reference materials15m
The measurement of amounts of plutonium is recognised as one of the most important tasks in fissile material control. Public opinion is especially sensitive to this element, which presents analysts with a difficult task of measuring plutonium at all levels from large (multi-gram) amounts down to traces in the environment.
The Institute for Reference Materials and Measurements (IRMM) is one of the few institutes worldwide that produces and certifies plutonium reference materials. They are part of a systematic IRMM programme to supply spike isotopic reference materials of various isotopes, in particular uranium and plutonium, at different concentrations.
Plutonium spike solutions present unusual problems that impinge on the certification of the isotope amounts. Due to radioactive decay certified values have to be constantly corrected, a process that leads to an increase in uncertainty depending on the spike isotope composition. The solutions also have a possibility of being unstable over time, probably due to radiolysis of the solutions.
At IRMM plutonium spikes are available for the isotopes 239Pu, 240Pu, 242Pu and 244Pu. This enables us to make an inter-comparison of the values of these spikes. An Inter-calibration campaign using state-of-the art measurement procedures has therefore been carried out at IRMM linking the plutonium spike reference materials available at the institute. The following spikes were used in the program: IRMM-049c (94.1% 242Pu), IRMM-049b (99.9% 242Pu), IRMM-046b (94.3% 242Pu and 98.0% 233U), IRMM-083 (98.97% 240Pu) and IRMM-042a (97.9% 244Pu), IRMM-081a (97.8% 239Pu) from CETAMA were used.
As comparison material a recently prepared 239Pu large-sized dried (LSD) spike, IRMM-1027M and external isotopic reference materials NBL CRM-131 and CETAMA MP2 were used for isotope dilution mass spectrometry (IDMS).
The uncertainties for the IDMS were estimated according to the Guide to the Expression of Uncertainty in Measurement (GUM). The results obtained by IDMS using the various spike isotopic reference materials will be presented and discussed. This inter-calibration study confirms the traceability of the values of the plutonium isotopic contents to the SI. Furthermore conclusions can be drawn for the need of recertification of particular reference materials.
(Institute for Reference Materials and Measurements (IRMM), JRC, European Commission)
Poster Appetisers - Nuclear Methods in Medicine, Radiopharmaceuticals and Radiodiagnostics, Labelled CompoundsRed Hall
Determination of cation exchange capacity of fucoidic sands for Cs<sup>+</sup> and <sup>2+</sup> under dynamic column conditions20m
In the framework of the development of remediation scenario of underground areas affected by chemical mining of uranium in the locality of Stráž pod Ralskem a complex geochemical and transport model is generated, which comprises interaction of rocks and groundwater affected by acid leaching. The chemical remediation processes also require the knowledge of the properties of the affected rocks. One of the important rock constituents are fucoidic sands, which constitutes significant part of the cenoman aquifer. Therefore it is a great importance to determine, among others, their cationic exchange capacity (CEC) toward univalent and divalent cations. In this paper results on the study of sorption and desorption behavior of Cs+ and Sr2+ on column of fucoidic sands under dynamic flow conditions are presented and their CEC for these two cations are determined. The determination of CEC is based on the construction of respective breakthrough curves using 137Cs and 85Sr radionuclides as isotopic indicators in laboratory experiments. The samples were taken from several parts of the bore hole in the area of interest. Undisturbed cores of 5 cm in diameter and 10 cm long were put in the glass columns and the cores were perfectly tightened using acrylate resin. For the study of sorption/desorption cycle the so-called background groundwater was applied. The concentration of 10-6 mol/dm3 of Cs+ and Sr2+ in liquid phase individually was established using neutral salts of CsNO3 and Sr(NO3)2, resp. The groundwater was introduced at the bottom of the columns by a multi-head peristaltic pump at about 4 cm3/h of a constant flow-rate. The results show that the CEC capacity of the investigated fucoidic sands for 137Cs and 85Sr is 0.1–1.5 μmol/100g and 0.05-0.5 μmol/100g, respectively, in dependence on the evaluation of corresponding breakthrough curves. Some differences in the behavior of the cores during the experiments have also been explained.
(Nuclear Research Institute Řež plc)
Dissolved gas measurements of the cooling ponds of Paks Nuclear Power Plant, Hungary20m
The aim of this work was the investigation of the effect of nuclear fuel rods to the composition of the dissolved gas in the cooling water of the cooling ponds of Paks Nuclear Power Plant (Paks NPP).
In normal cases after three-year usage in the reactor the spent fuel elements are stored in cooling ponds for years before delivering out from the reactor area. In April of 2003 with the failure of the cleaning procedure of fuel rods from reactor No. 2 some elements remained in service pool No. 1. For better handling of this situation and planning the repairing procedure several parameters must be considered. The gases dissolved in the coolant, especially the ones produced by fission or decay, are good indicators of the variation in state parameters of the system in this situation as well as in the case of working reactors. Parallel with the measurements of dissolved gases in the coolant for surveying the kilter of the nuclear fuel remained in service pool No.1 we also measured these parameters in the cooling ponds as a reference. The reason was the similar technological situation because in both cases the coolant contains out of work fuel elements and the headspace gas above is air with atmospherically pressure.
In this work we investigated the effect of the nuclear fuel rods to the composition of the dissolved gas in the coolant of the cooling ponds and the service pool No.1 of the reactor No. 2 of Paks NPP. We measured the quality and the quantity of the dissolved gases and the isotope compositions of the noble gases produced in fission or decay. For these aims sampling and measuring methods were developed.
Our results help to ascertain the possible ways and rates of gas generation processes caused by the presence of nuclear fuel rods in the cooling water.
Electrochemical behaviour of selected actinides and lanthanides in molten fluoride salts FLiNaK and FLiBe20m
The presented work is focused on research of basic electrochemical properties of several actinides and lanthanides representing the fissile material and fission products in suitable molten fluoride melt. The general framework of this work is to study the electrochemical behaviour of systems relevant for possible future use in the Generation IV reactor concepts.
Results of cyclic voltammetry, chronopotentiometric and electrolytic experiments with uranium and several lanthanides in the LiF-NaF-KF (acronym FLINAK) are presented. Mechanisms of electrochemical reduction were investigated. Recorded reduction steps were investigated and described in terms of reversibility, number of exchanged electrons, diffusion coefficients etc. For the lanthanides, it seems impossible to reach solid deposit of studied lanthanide on the electrode. For uranium, deposition depending on electrode material and shape was studied with special attention given to its deposition on reactive (Ni) working electrode.
Beryllium based molten salts 7LiF-BeF2-ZrF4 and 7LiF-BeF2 were used as a carrier melts during Molten Salt Reactor Experiment and Molten Salt Breeder Reactor projects  and are considered as a key systems also for the future use. In the LiF-BeF2 melt (acronym FLIBE), the work was focused on research of uranium behaviour in the melt and the influence of its composition between two eutectic points of FLIBE (eutectic compositions of FLIBE melt are defined by molar ratio of BeF2 x=0.328 and x=0.531).
Also the general consequences of obtained data for the development of separation process are concluded.
 C. F. Baes, Journal of Nuclear Materials 51:149 (1974).
(Nuclear Research Institute Řež, plc)
EPR measurements on N-bearing ligands used in spent nuclear fuel reprocessing for An(III)/Ln(III) partitioning20m
A future goal for the reprocessing of spent nuclear fuel is the transmutation of long-lived minor actinides, such as americium and curium, into short-lived isotopes by means of neutron irradiation. In order to develope an effective transmutation process, it is necessary to separate the trivalent minor actinides, An(III), from the trivalent lanthanides, Ln(III) by means of two subsequent solvent extraction processes: i) DIAMEX to extract both Ln(III) and An(III) from PUREX raffinate and ii) SANEX to obtain the selective extraction of An(III) from the output of DIAMEX process.
The present work concerns the degradation due to ionizing radiation released by radionuclides to the selected solvent system involved in the SANEX process. The high-energy radiations are able to modify the ligands molecules structures changing their extractant capabilities. In particular, several aspects must be considered when selecting a molecule to be used in the mentioned process: chemical stability; solubility in organic diluents; extraction capability of metal ions with appropriate distribution ratios; and resistance towards irradiation. Some aza-heterocyclic extractant molecules C2-BT (5,6 diethyl (1,2,4 bis-triazine), C2-BTP (2,6-diethyl(1,2,4-triazine-3-yl)pyridine), C5-BTBP (6,6’-bis-(5,6-dipentyl-[1,2,4]triazine-3-yl[2,2’]bipyridinyl) and CyMe4BTBP (2,6-bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]triazin-3-yl)-[2,2’]bipyridinyl), constituted by pyridine and triazine aromatic rings with chelating nitrogen donor atoms, have been studied during the European Research Project EUROPART. Furthermore, the mentioned molecules present aliphatic side groups as, n-carbon alkyl substituents (methyl, ethyl or penthyl chains), or cyclohexyl moieties to ensure their lipophilic behavior after coordination of trivalent metal ions during liquid-liquid extraction processes. To carry out studies concerning radical mechanisms, the abovementioned molecules were irradiated in a Co-60 gamma irradiation facility (up to 113 kGy with a dose rate of 0.5 kGy/h), at 77 K to reduce radicals reactivity before investigations by EPR Spectrometry. A preliminary EPR screening on the four ligand molecules shows the presence of radiation-induced radicals on both the aromatic and aliphatic sides of the ligands. In particular, irradiation of C2-BTP in alcoholic solutions highlighted the formation of azacyclohexadienyl radical as intermediated specie. The azacyclohexadienyl radical has been recognized by simulated spectra using appropriate hyperfine constants, and similar signals have been collected also for irradiated solution of C5-BTBP. The EPR spectra collected on samples of C5-BTBP powder, irradiated in air, disclosed the formation of peroxide radical species ROO•. Further simulations on the EPR spectrum collected at 208 K revealed definitively the presence of peroxide species on C5-BTBP.
In conclusion, taking into account the peroxide radical formation proven on C5-BTBP powder, it was possible to propose several radical mechanisms able to modified the extractant capabilities of the investigated molecules.
(European Commission, Joint Research Centre, Ispra Site Directorate, Italy)
Evaluation of dihexyloctanamide as extractant under plutonium rich feed conditions20m
Tributyl phosphate (TBP) has been the work horse of Nuclear Fuel Reprocessing Technologists for more than five decades. However, based on five decades of experience on spent fuel reprocessing, certain problems have also been identified with the use of TBP as extractant. Prominent amongst them are: (a) high aqueous solubility, (b) poor radiation stability and interference of degradation products during stripping of Pu/U, (c) poor decontamination factor (DF) values of Pu/U with respect to fission products, (d) low limiting organic concentration (LOC) of Pu(IV), and (e) a large volume of secondary (phosphate) waste. In addition, as a consequence of the radiolytic degradation of TBP, the extraction and stripping behavior of U/Pu, and hydrodynamic properties such as viscosity, density, and phase disengagement time, are adversely affected. These problems are of particular concern to the separation scientists and technologists during the reprocessing of short-cooled thermal reactor fuels as well as of fast reactor fuels. In this context, completely incinerable N,N-dialkyl amides have been evaluated extensively as alternative extractants to TBP. Studies carried out at Radiochemistry Division, BARC, India, on the development of new extractants for the reprocessing of spent fuel suggested that a straight chain N,N-dihexyloctanamide (DHOA) was promising alternative to TBP for the reprocessing of irradiated uranium based fuels.
This paper deals with the evaluation of DHOA vis a vis TBP as an extractant for plutonium rich feed solutions encountered in fast reactor spent fuel reprocessing. Solvent extraction studies were carried out to evaluate the two extractants DHOA and TBP using pure 20 g/L Pu as well as simulated Pu rich feed solution containing 20 g/L Pu, 7 g/L U, fission products (FPs) and structural materials (SMs) at 4 M HNO3. DPu values were higher for 1.1 M DHOA (26.4±1.2) for pure Pu as well as for simulated feed solution as compared to those for 1.1 M TBP (16.6±2.2) under identical conditions. Under simulated feed conditions, two successive stages were sufficient for quantitative extraction (>99.9 %) of Pu(IV) employing 1.1 M DHOA as extractant and maintaining organic-to-aqueous phase ratio (O/A) as 1. On the other hand, three stages were required in the case of 1.1 M TBP as extractant. Plutonium stripping experiments using 0.5 M HNO3 as strippant (without any reductant) showed that only six stripping stages were sufficient for quantitative stripping of Pu from loaded DHOA phase. On the other hand, >10 stages were required for Pu stripping from loaded TBP phase and it became further difficult with the aging of the organic phase. By contrast, no problem related to Pu retention was observed for aged DHOA solution. These studies also suggested that DHOA is a promising extractant for coprocessing of U/Pu from spent fuels. In addition, DHOA was found distinctly better than TBP with respect to FPs and SMs decontamination.
(BARC, MUMBAI, INDIA)
Evolution of the redox potential in the corrosion system20m
The knowledge of chemical conditions, especially of redox potential, inside waste packages with radioactive wastes is important for determination of radionuclides speciation and their leaching rate after failure of waste packages. Conditions inside waste packages will be determined primarily by the reactions of thermodynamically unstable iron with groundwater penetrating into waste packages and by the nature of the iron corrosion products formed. The main corrosion products of iron corrosion are Fe (II) ions, hydrogen and products of reactions of these species with species presented in water flowing into waste packages. The composition of water will correspond to the composition of ground water affected by other engineered barriers.
The rate of the corrosion reaction, the rate of oxidation and hydrolysis of Fe2+ and the rate of the formation of precipitation products will govern the development of Eh inside waste packages. One possibility of estimating chemical conditions in such complex systems is to use advanced geochemical models. A great disadvantage of these models is that a lot of important input data must be estimated. This can lead to great uncertainty about the real conditions inside waste packages.
The main aim of this work was therefore to measure redox potential (Eh) in simplified systems simulating the conditions inside waste packages and the effect of iron corrosion on Eh development inside waste packages after ingressions of groundwater. The results can then be used to validate geochemical models.
The corrosion systems consisted of the carbon steel plates and the synthetic bentonite porewater. The apparatus was put into anaerobic box (O2 < 0.1 ppm), where redox potential was measured by platinum and gold electrode. The corrosion rate of carbon steel was determined during experiment by measuring hydrogen evolution and then from weight loss of samples.
The results show that the values of the redox potential during the experiments firstly sharply decrease and then slowly increase. Opposite behaviour was observed at measuring pH, where values of pH first slightly increased and then slowly decreased. The concentration of Fe3+ ions after the experiments was negligible in comparison with Fe2+ concentration. The corrosion rate at 50 °C was almost constant during corrosion experiment, while the corrosion rate at 60 and 70 °C was very fast at the beginning of corrosion, but then significantly slowed down. It seems that the effect of temperature on corrosion rate is affected by the nature of corrosion products formed on the surface of metal.
The experiments provide useful information about evolution of the redox potential and other parameters which can be expected inside waste packages with radioactive wastes, but time of the experiments carried our so far was relatively short (30 days). In the future, long-term experiments must be performed under various conditions to verify the results obtained.
(Nuclear Research Institute Rez)
Extraction of Ln/An from highly acidic solutions using cobalt bis(dicarbollide) functionalized with complexing CMPO group.20m
The nuclear fuel reprocessing isues an important problem in respect to handling of the family of actinides which represent the main source of radiotoxity during long-term storage. The separation of long lived radionuclides from liquid radioactive waste enables these hazardous elements to be either conditioned more safely in specific matrices, or destroyed by transmutation. Thus, elimination of minor actinides would lead to significant reduction of volume and radiotoxicity of the waste for the final storage and should consequently minimize the possible risks to biosphere. Several extraction concepts were proposed for separation of Ln and An from fission product mixture during last ten years.
In this paper, extraction of trivalent lanthanides and actinides using a compound based on covalent combination of cobalt bis(dicarbollide) (1-) anion (COSAN) and CMPO (N,N- dialkyl carbamoyl methyl diphenyl phosphine oxide) complexing group of the formula [8-Ph2P(O)-CH2C(O)N-t-C8H17-(CH2-CH2O)2-1’,2’-C2B9H11)-3,3’-Co]- will be presented. This compound was selected for detailed tests from a broad panel of other derivatives (differing in the substitution at the CMPO function and its bonding to the COSAN cluster 1,2 due to very effective extraction of Ln(III) and An(III) from highly acidic solutions (3M HNO3), good solubility characteristics and an easy synthetic accessibility in a large scale. Extraction efficiency under different conditions (acidity, reagent concentration, macro amounts of metals, etc.), solubility in different solvents and chemical stability were tested to evaluate a possible technological use. The composition of extracted complex was studied. Extraction from fission product mixture revealed very effective separation from the majority of fission products with separation factor exceeding 1000. For some fission products, the presence of complexing agents was necessary.
1. P. Selucký, J .Rais, M. Lučaníková, B. Grüner*, M. Kvíčalová, K. Fejfarová and I. Císařová: Radiochim. Acta 96 (4-5), 273-284 (2008).
2. B. Grűner, M. Kvíčalová, J. Plešek, V. Šícha, I. Císařová, M. Lučaníková, P. Selucký, J. Organomet. Chem., 694 (2009) 1678-1689.
We thank for partial support from Grant Agency of the Czech Republic (Project No. 104/09/0668), Radioactive Waste Repository Authority (Project 2007/006/Šumb and 2009/002/Šu), EU Project EUROPART (6th F.P.) and Research Plan AV0Z40320502 from AS CR.
(Ústav jaderného výzkumu Řež)
Functionalized latex particles for preparation of colloid-stable nanosized selective sorbents and composite materials for decontamination of radioactive waste20m
Here we discuss preparation of a new type of colloid-stable nanosized sorbents based on functionalized latex particles, which can be directly applied for decontamination of liquid and solid radioactive wastes or used for construction of fibrous or mesoporous composite sorption materials. Carboxylic latex (siloxane-acrylate and polystyrene-acrylate) functionalization is performed via immobilization of nanocrystals of the selective to radionuclides sorbents (ferrocyanides of transition metals and sulfates of calcium/barium) into the polymer matrix.
The presence of anionic centers on the latex particle surfaces stipulates for the possibility of binding to them ions of divalent metal-precursors of selective sorbents. With the added metal concentration increase one can observe the decrease of electrokinetic potential (by module) at invariable particle size. The residual negative charge on the surface provides the system high colloid stability. To form stable nanoparticles of a selective sorbent it is crucial to limit the amount of introduced divalent metal ions by the beginning of the plateau on the dependence of electrokinetic potential on the metal concentration in solution. AFM imaging of the functionalized latex particles shows that, as a result of introducing cobalt ferrocyanide nanoparticles, the initially spherical polystyrene-acrylate (PA) particles transform into a cubic shape, which is characteristic for ferrocyanide macrocrystals.
Due to immobilization into stable polymer colloids, the selective sorbents nanoparticles preserve high stability at filtration in porous media. After 50 filtration cycles of emulsion of the siloxane-acrylate (SA) latex with immobilized nanoparticles of cobalt ferrocyanide through a layer of natural zeolite, the cobalt content in the emulsion remained nearly constant. When such colloid-stable sorbents are directly applied for decontamination, after radionuclides sorption the stability of such systems can be controllably reduced by addition of cationic flocculants, thus providing high efficiency of radionuclide removal from solution. The combination of high selectivity of nanosized sorbents immobilized into latex particles with ease of their removal from solution by flocculation/coagulation process enables one to recommend the developed schemes for different materials decontamination, first of all, for solid bulky wastes – soils, grounds, metal constructions. To extend suggested approach for production of different types of sorption materials pre-formed colloidal-stable selective sorbents were deposited on carbon fibers by electrochemical method or used as a template during formation of mesoporous SiO2, ZrO2 and TiO2 sorbents. The selective sorption materials obtained showed good kinetics of radionuclides sorption and distribution coefficients for cesium up to 1e+7.
(Institute of Chemistry FEBRAS)
Immobilisation of cesium and divalent metals into single-phase stuffed tridymite-based ceramics20m
The mixed phosphates with high caesium concentration of the compositions CsMePO4 (Me − divalent metal with a tetrahedral coordination) adopting a stuffed β-SiO2 tridymite structure are studied as perspective materials for a 137Cs γ-radiation sources to be used in medic applications. For the purpose of 137Cs source production from commercial radiocaesium liquid wastes (nitrate caesium solutions containing Me impurities) it is necessary to know the possibilities of single-phase composition formation in the systems CsMe'1-xMexPO4 with different Me cations.
In this work we have studied phase formation regularities and thermal behavior of mixed complex phosphates of the CsMg1-xMexPO4 (Me = Mn, Co, Ni, Zn, Cu) systems. The samples were synthesized by precipitation method. The aqueous solution of phosphoric acid taken in accordance with the stoichiometry sample was added to stoichiometric mixture of caesium and metal (Me) nitrate or chloride solutions. The reaction mixture was dried at 353 K and thermally treated at 873 and 973 K. All the thermal treatment stages were alternated with careful grinding. The obtained samples were crystalline powders.
X-ray powder diffraction measurements indicated that continuous (Me = Mn, Co, Ni, Zn; 0 ≤ x ≤ 1.0) or limited (Me = Cu; 0 ≤ x ≤ 0.4) solid solutions of the tridymite structural type were obtained. The results of scanning electron microscopy and electron microprobe analysis monitored the homogeneity of the samples and conformity of their compositions to the theoretical values.
The phase formation regularities and the dependences of the unit cell parameters of solid solutions CsMg1-xMexPO4 on their compositions x were studied. Three polymorphic forms with similar type of a framework are possible for tridymite structure type phosphates: monoclinic (sp. gr. P21/a) and two orthorhombic (sp. gr. Pn21a and Pnma). For many phosphates with temperature increase the phase transitions P21/a → Pn21a → Pnma are observed.
Due to the differential scanning calorimetry results, the phosphates CsMePO4 with Me = Co and Zn had two polymorphic transitions in the temperature interval from 423 to 583 K. The phosphate CsMgPO4 underwent phase transition at 236 K. The second harmonic generation results showed phosphate crystallization in centrosymmetric (P21/a or Pnma) or non-centrosymmetric (Pn21a) space groups. The transition from Pnma to Pn21a space group was accompanied by absorption band disappearance of valency symmetric vibrations in IR-spectra of phosphates.
A leaching rate of approximately 10−5 g•cm−2•d−1 for Cs was determined from Soxhlet leaching of the CsMgPO4.
Thus, the possibility of simultaneous incorporation of caesium and different metals with oxidation degree +2 (which present in commercial radiocaesium liquid wastes) is shown in the tridymite structure with formation of wide or continuous solid solutions. Such tridymite-like phosphates may be a perspective candidate both for radiocaesium immobilisation and caesium isotopic source production instead of soluble CsCl used nowadays.
This work was supported by the Russian Foundation for Basic Research (Projects nos. 08-03-00082, 09-03-90731).
Impact of hydrogen generated by iron corrosion on compacted bentonite in deep geological repository20m
A large number of processes will influence performance of deep geological repository of radioactive wastes until the activity of radionuclides decay to a negligible level. One of the very important processes is generation of gases, and particularly of hydrogen, which will be formed primarily by anaerobic corrosion of metals and by radiolysis of water. High pressure formed in the vicinity of waste packages due to accumulation of hydrogen can cause failure of sealing materials and contribute to fast release of radionuclides to the geosphere after waste package failure. This contribution presents the results of laboratory experiments, which simulated the phase of repository evolution after ingression of water in failed canister with spent fuel assemblies, which is connected with significant generation and accumulation of hydrogen in free voids of waste packages and at interfaces of waste packages and compacted bentonite used as a sealing material. Corrosion of carbon steel canisters inside walls is simulated by corrosion of iron powder with high surface. It was found that after an increase of pressure of hydrogen to the values exceeding some threshold values, which depends on density bentonite, hydrogen is released to geosphere in pulses due to formation of preferential paths. This is connected with a significant increase of permeability of bentonite from values of approximately 10-24 m2 to 10-18 m2 within the breakthrough time. The pressure needed to reach breakthrough is decreased with number of breakthrough pulses. Data obtained in experiments enable us to understand more closely to the processes occurring in a repository and to avoid conditions, which could lead to the failure of sealing materials and fast release of radionuclides to the geosphere and the environment.
(czech chemical society)
Improvement of radionuclide fixation in cement matrixes during immobilization of liquid radioactive waste20m
Cementation provided by mixing of concentrated radioactive waste (RAW) and cement is the most common procedure for immobilization of medium- and low-level radioactive salt-containing waste of radiochemical industry. However, low degree of inclusion of solidified waste in concrete (especially from concentrated salt-containing solutions owing to deterioration of the concrete properties) and noticeable leaching of some fission elements require development of additional barriers at storage of such RAW. Therefore, addition of RAW into the concrete not in the form of solutions but in the form of sorbents saturated with radionuclides can decrease leaching and, in turn, can improve degree of cesium inclusion without decrease in the strength and some other properties of the concrete monolith.
Our studies were aimed at treatment of the solutions with complex chemical composition from the units of RAW concentration and fractionation and of the spent decontamination solutions.
To include radionuclides containing in liquid RAW in the concrete the possibility of using of super-stoichiometric sorption was studied. This method allows increasing saturation with respect to many radionuclides by a factor of 5-20. Chemical treatment of the sorbent preliminarily saturated with cesium provides stronger fixation of given radionuclide in the solid matrix. Inclusion of sorbents saturated with radionuclides in the concrete increases 137Cs content in the solidified matrix by one-two orders of magnitude without any changes in the strength properties of the resulting composites. At the same time, the leaching rate of 137Cs decreases by a factor of 4-5.
Surface treatment of the resulting composites liquid and supercritical CO2 (so-called carbonization procedure) was also studied to improve fixation of radionuclides in the concrete blocks.
Combination of above procedures allows reducing cesium leaching from the concrete blocks by more than two orders of magnitude.
(Khlopin Radium Institute RPA)
Production of artificial metal ruthenium from irradiated technetium20m
Long-lived nuclide 99Tc is accumulated as a fission product in 1-3 kg/t quantities in fuel of nuclear power plants. Transmutation of technetium by the action of neutrons is the most cardinal method for its neutralization and disposal; this leads to the production of artificial stable 100Ru, 101Ru. Several technetium targets have been irradiated at SSC RIAR. Metal technetium in the form of disks was irradiated in the neutron trap of the SM reactor. Specimens resulting from the irradiation were found to represent Tc-Ru alloys. Prior to our work no description of the production of artificial metal ruthenium from irradiated technetium was available elsewhere.
This paper presents two different procedures for the production of artificial metal ruthenium from irradiated technetium targets. In one of this procedures the targets were dissolved in KOH solutions at the presence of KIO4 followed by precipitation of Ru(IV) hydroxide with ethanol. To purify the produced ruthenium from technetium traces, it was distilled as RuO4 into the ethanol aqueous solution where it was reduced and precipitated as Ru(IV) hydroxide. To produce metal ruthenium, Ru(IV) hydroxide precipitate was calcinated up to RuO2 and then reduced to metal in hydrogen flow.
According to the other procedure for separation of stable ruthenium from the irradiated technetium target use was made of a catalytic oxidation with ozone. Firstly, a Tc-Ru alloy specimen was placed into HNO3 or HClO4 solution containing Ag(I) ( or Co(II) ) ions. Then the ozone-oxygen mixture was bubbled through the solution. Formed by action of ozone Ag(I) ( or Co(II) ) ions oxidized the alloy (Tc and Ru) components transferring them to the solution. Then RuO4 and some part of HTcO4 were distilled to NaОН solution where RuO4 was reduced to sodium ruthenate. At the next process stage the Ru(IV) hydroxide was precipitated from the solution by the action of ethanol acting as a selective reducer of Ru(IV). The precipitate was placed into water and the ozone-oxygen mixture was bubbled through the hydroxide suspension formed in water. The Ru(IV) hydroxide was reduced to RuO4 with ozone, which was distilled to ethanol aqueous solution by the bubbled gas flow. The produced Ru(IV) hydroxide was transformed to RuO2 , which was reduced to metal in the helium-oxygen mixture.
(JSC "State Scientific Center - Research Institute of Atomic Reactors")
Pyrochemical and electrochemical separations studies on plutonium (Part 2)20m
Pyrochemical separations , involving molten salt and metal media , by liquid/liquid extraction or electrorefining are studies for nuclear defense and civil applications. The electrochemical properties of plutonium have been studied in molten salt-ternary eutectic mixture NaCI-KCI-BaCI2, equimolar mixture NACI-KCI and pure CaCI2 - and in liquid gallium at 1073 k. These processes concern actinide separations , However , lanthanides , such as cerium, are often used as surrogates.The first steps of a pyrochemical process development consist in the solvent media.Activity coefficients of the solutes in the two phases, that described the solvent-solute interaction , are important thermochemical parameters to predict separations efficiency and to assess the solvents influence . As nuclear defense scientist, I discuss the advanced developments to separate plutonium by electrochemical method that has been supporting the developments of pyrochemical processes involving plutonium as main goal and actinides separations.
Keywords/ Electrochemical reactions, Molten salt ,Metal media, Activity coefficient of plutonium.
Prof.Dr.Mr.ASHRAF ELSAYED MOHAMED MOHAMED
(World Institute of nuclear secuirity"Austria')
Qualification of low and intermediate level radioactive wastes (L/ILW) within the framework of the “Demo” project by a Triathler type portable liquid scintillation spectrometer in Püspökszilágy, Hungary20m
In the Püspökszilágy Radioactive Waste Treatment and Disposal Facility, Hungary being in operation since 1976 many works began to solve the storage of the non-power plant radioactive waste of Hungary to fulfil the increasing safety demands. In the framework of this procedure the exhumation of 66 pieces of reinforced concrete near-surface vaults with the size of 70-140 m3 each (called vault “A”) was launched together with further renewal works. The exhumation of the A11, A12, A13 and A14 vaults were included in the “Demo” project, in the course of which the aim was to find the proper measurement and waste-backfilling technique to adapt them in the case of the further vaults. To identify the H-3, C-14 and Sr-90 isotopes a Triathler type portable liquid scintillation spectrometer was used together with a rapid and well-reproducible swipe sampling method. At the evaluation of the 4000 samples taken the expected total activity value was obtained. The removal of certain waste packages was fulfilled to gain room to allow the disposal facility to accept further waste in the future. The measurement technique is therefore well-applicable in the case of the “A type” vaults.
(Isotoptech Co. Ltd., Debrecen, Hungary)
Radioactive waste destruction using molten salt oxidation20m
A molten salt oxidation (MSO) process is being studied for the safe and
effective destruction of organic components of radioactive waste. The
work involves a laboratory-scale molten salt oxidation system where solid
or liquid waste is injected into a bed of molten carbonate salt in the
presence of an oxidizing gas. The relatively simple MSO process
completely destroys organic compounds, and the carbonate salt neutralizes
any generated acid gases and retains the radioactivity. In the past, high
melting point salts have been used with air oxidation. In these studies,
the use of low melting point salts and stronger oxidizing agents are being
investigated for the destruction of radioactive waste oil and ion exchange
resins. Work on the recovery of uranium from lignites will also be
(Nuclear Research Institute Rez plc.)
Removal of Cs, Sr, Pu and Am from contaminated solutions by inorganic sorbents20m
Recently growing concern about contamination of the environment with radioactive and non-radioactive pollutants resulted in intensive studies related to the development of new technologies for separation of radionuclides from liquid waste. These new technologies should be based on highly selective materials (e.g., crystalline titanium silicates) which are hard to decompose over a wide range of pH, which remain stable at high temperatures, which are resistant to ionizing radiation and which are able to operate in the presence of a great excess of competitive ions, organic solvents and oxidants. However, complicated technologies, high capital and regeneration costs stimulated studies to develop low-cost and efficient technologies based on naturally occurring minerals such as zeolites and clay minerals. Another option could be an application of amorphous porous mixed oxides - a rapidly developing class of materials prepared by sol-gel procedures, the main benefit of which are very simple procedures conducted under mild reaction conditions in the ambient atmosphere. Ferrites and a variety of iron-containing minerals such as akaganeite, feroxyhyte, ferrihydrite, goethite, hematite, lepidocrocite, maghemite and magnetite are also a promising class for the treatment of liquid wastes containing radioactive and hazardous metals.
The aim of this study was to prepare amorphous TiSi by sol-gel procedures, to synthesize various iron oxides, to characterize them using IR, XRD, Mössbauer spectroscopy and to carry out a comparative assessment of possible application of these low-cost synthetic inorganic sorbents with conventional and natural sorptive materials in liquid waste treatment technologies to remove long-lived radionuclides such as Cs, Sr, Pu and Am.
Results obtained using a bath method, ICP-MS, γ, α spectrometry and β counting revealed that titanium silicates, synthesized using TiOSO4 without reference to the chosen method - a precipitation or sol-gel, showed the highest sorption ability towards studied radionuclides. Magnetite and clay minerals showed better sorption ability towards americium. The highest Pu Kd values and better Pu sorption kinetics were found for synthetic iron oxides. An increase in the Pu Kd value by a factor of 6.8 found for magnetite/hematite composite in comparison with the pure magnetite suggests that this sorbent is efficient for plutonium removal and it is promising for its separation from contaminated solutions. TiSi tested in this study showed close sorption ability towards studied radionuclides in comparison with crystalline TiSi, whereas they were synthesized under mild conditions using cheaper materials. In addition, TiSi prepared by the sol-gel method has certain advantages in comparison with the fine powder TiSi because of a huge potential for tailoring of chemical composition, porosity and surface properties, as well as for the production in the granular form, which is especially important for practical purposes.
The research was supported by the Ministry of Education and Science of the Republic of Lithuania and the Lithuanian State Science and Studies Foundation projects V-19/2009.
(Institute of Physics)
Sorption and diffusion changes of <sup>134</sup>Cs, <sup>99</sup>Tc and <sup>129</sup>I radionuclides on bentonites at various conditions20m
Radionuclides of 99Tc and 129I belong among the fission products of spent nuclear fuel and are the largest contributions with long-term nuclear waste. The high proportion of risk from these radionuclides is due to their large inventories in many types of waste, long half-lives, and the perception that they are highly mobile in the environment and therefore play potentially large role in long-term dose assessment. Computer-modeling methods were used to calculate equilibrium thermodynamic principles, the distributions of predominant aqueous species, and potential solubility controls for the environmentally important oxidation states of each of the contaminants of concern. The Eh-pH diagrams of individual chemical species of the tested radionuclides were calculated by the geochemical software tool Geochemist’s Workbench. The data obtained from the model calculations corresponded with experimental results. The chemical stability of the bentonite was studied on a series of long-term pressure and temperature loaded bentonite samples that were selected with the aim of constructing a behavior profile of the bentonite buffer material in the experimental container. The chemical stability of the loaded bentonite samples was evaluated on the basis of their ion exchange capacity, the migration behavior of selected radionuclides and a determination of the leachable components of bentonite into redistilled water. The results obtained in this study were compared with the values for the unloaded bentonite material. It was found that long-term pressure and temperature gradients do not have a significant influence on the changes in ion exchange capacity of the bentonite material. These results make a major contribution towards determining the migration of radionuclides on bentonite, especially cationic forms of radionuclides. Electromigration methods and thin layer chromatography with radiometric detection were used for the identification of technetium and iodine chemical forms in the studied solid-liquid systems. Migration studies of the radionuclides 134Cs in the form of the Cs+ cation and 99Tc in the form of the pertechnetate anion were described on the basis of two dominant processes that both include sorption and diffusion. Dominant chemical forms of technetium under these redox conditions is insoluble TcO2.nH2O, which is formed by the reduction of pertechnetate anion to the oxidation state Tc(IV). The determined values of distribution and diffusion coefficients of the loaded bentonite samples corresponded with the values of the unloaded bentonite material. Ion exchange at the surface sites of bentonite corresponded with the control mechanism of Cs+ cation sorption on bentonite in that both were simultaneously influenced by competitive cations present in the aqueous phase(Na+, K+, Ca2+, Mg2+). To retard the migration of selected radionuclides (99TcO4-, 125I-) released from spent nuclear fuel after the failure of a container, the reducing effects on the concentration of these radionuclides by container corrosion products and of some additives on the bases of Fe compounds in various oxidation states were examined in aqueous media in contact with bentonite.
(Institute of Chemical Technology)
Sorption behaviour and speciation of neptunium(V) on Opalinus clay20m
The sorption of Np on clay such as Opalinus clay (OPA) is one of many important processes that affect the migration and retardation of Np in the geosphere. Clay formations are under consideration in several European countries as a potential host rock for high-level radioactive waste repositories . We studied the sorption of Np(V) onto OPA (from Mont Terri, Switzerland) both by batch experiments and X-ray Absorption Spectroscopy (XAS). The aim of this study was to obtain a mechanistic understanding of the interaction of Np(V) with the OPA surface. The obtained information are necessary for the safety assessment and detailed planning of nuclear repositories.
The batch experiments were done under aerobic and anaerobic conditions. The sorption of Np(V) on OPA was studied as a function of many chemical parameters such as pH (6-10), background electrolyte (synth. OPA pore water, saturated calcite solution, and 0.1 M NaClO4), partial pressure of CO2, and presence/absence of humic acid (HA). The sorption curves for 8·10-6 mol/L Np(V) in saturated calcite solution obtained under aerobic and anaerobic conditions, respectively, show that the adsorption edge occurs between pH 7-8. Maximum sorption was observed at pH 8.5 with 65% sorption under aerobic conditions and 80% under anaerobic conditions, respectively. Under anaerobic conditions the reduction of Np(V) to Np(IV) by Fe(II) minerals of OPA causes a stronger sorption. At pH > 9 Np sorption decreased due to the complexation of Np with carbonate in aqueous solution . Molecular-level information was obtained by X-ray Absorption Fine Structure (EXAFS). EXAFS spectra were measured in fluorescence mode at the Rossendorf Beamline ROBL at ESRF. Several samples at pH 7.6 and 8.5 with a total Np(V) concentration of ~ 8·10-6 mol/L were prepared under aerobic and anaerobic conditions. The amount of Np sorbed in the EXAFS samples was in the range of 50-121 ppm. Np L3-edge X-ray Absorption Near-Edge Spectra (XANES) showed that in all aerobic samples the pentavalent oxidation state of Np was dominated. The Np L3-edge EXAFS spectra of the anaerobic samples prepared in different background electrolytes showed the same EXAFS pattern, indicating that Np(V)-carbonato complexes are formed at OPA surface. More details as well as additional results will be presented and discussed.
The authors acknowledge the ESRF for provision of synchrotron beam time and thank the ROBL team for assistance during EXAFS measurements. This work was financially supported by the BMWi under contract No. 02E10166. D.R. Fröhlich has been supported by a fellowship of DFG-GRK 826.
 NAGRA: Projekt Opalinuston - Synthese der geowissenschaftlichen Untersuchungsergebnisse, Entsorgungsnachweis für abgebrannte Brennelemente, verglaste hochaktive sowie langlebige mittelaktive Abfälle. Technical Report NTB 02-03, NAGRA, Wettingen/Schweiz, 2002.
 V. Neck, W. Runde, J. I. Kim, B. Kanellakopulos, Solid-liquid equlibrium reactions of neptunium(V) in carbonate solution at different ionic strength. Radiochim. Acta. 65, 29-37 (1994).
(Institute of Nuclear Chemistry, Johannes Gutenberg-Universität Mainz)
Sorption of radionuclides to the cementitious material NRVB under near-field conditions20m
The current concept for the disposal of intermediate- and low-level waste in the United Kingdom involves the emplacement of the grouted waste confined in stainless steel canisters in a cementitious repository deep underground . The NRVB (Nirex reference vault backfill) is a cementitious material specially formulated for this purpose, composed by a mixture of ordinary Portland cement (OPC), hydrate lime (Ca(OH)2) and limestone flour .
The movement of the radionuclides away from the repository is expected to be retarded by their limited solubility under the chemical conditions present in the repository (high pH, due to the cement, and low Eh, due to corrosion of the waste canisters) as well as, by sorption processes.
In the present work, the sorption of a series of radionuclides (I-, Cs+, Ni+2, Eu+3, Th+4 and U+6) to NRVB was assessed under near-field conditions (highly-alkaline pH and anoxic conditions). The experiments were carried using NRVB-equilibrated water (pH ~ 12.6) in NaCl 0.1 mol dm-3 as liquid phase, under a N2 atmosphere (O2 and CO2 free), according to the procedure proposed by Sutton et al. . Linear, Langmuir and Freundlich isotherms were studied for all the radionuclides, and in all cases, the sorption of radionuclides fitted well with the linear model. The Rd (Csolid/Cliquid) observed experimentally varied in a wide interval that ranged from the low values of 0.012 and 0.033 dm3 g-1 for Ni+2 and I-, respectively, to values as high as 2870 dm3 g-1, obtained for Cs+. Results of the effect of cellulose degradation product on sorption to NRVB will also be presented.
When the Rd (Csolid/Cliquid) values of the radionuclides of interest for NRVB, were compared with the experimental Rd values for the individual components of NRVB, i.e. OPC, hydrated lime and limestone, it was observed that in the case of nickel and in absence of the organic ligands, Rd(NRVB) ≈ Rd(OPC) + Rd(Ca(OH)2) + Rd(limestone), confirming the validity of the additive model for this material.
 The viability of a phased geological repository concept for long-term management of the UK’s radioactive waste. Nirex report no N/122. United Kingdom Nirex Limited (2005).
 Harris, W. and Nickerson, A.K. The physical properties of the Nirex Reference Vault Backfill. NSS/R335, AEA-D&W-0450 (1997).
 Sutton, M., Warwick, P. and Hall, A. Uranium(VI) interactions with OPC/PFA grout. J. Environ. Monit. 5, 922-928 (2003).
The Radioactive Waste Management Directorate of the Nuclear Decommissioning Authority is thank for sponsoring this project
Sorption properties and behaviour of <sup>137</sup>Cs and <sup>90</sup>Sr on bentonite clays and magnox sludges20m
Within the nuclear industry, waste management and disposal issues, both within the plants themselves and in the surrounding areas, are complex and problematic. This is partially a result of many decades of discharges within the storage site. A major problem is in determining the nature and distribution of contamination within the environment, be this on site in surrounding host rock, or determining whether migration has occurred to such an extent that contamination has breached the boundaries of the site and reached the public domain, or whether contamination has been released to atmosphere, for example.
It has been suggested that there may be significant quantities of contaminated land arising from breaches in radionuclide storage. Therefore, an understanding of the transportation of radionuclide waste in the environment around storage ponds and silos on waste sites, as well as an understanding of the behaviour within the ponds, is essential in future waste remediation strategies.
One area of significant interest is the migration of 137Cs and 90Sr radionuclides in contaminated clay soils, as migration has been shown to be significantly faster than expected in some areas. Although exact figures are not known, information provided by a UK operator suggests that 137Cs and 90Sr are progressing through the surrounding area quicker than the expected annual rate of 6 cm/year, for this type of material.
Sorption studies carried out using 137Cs and 85Sr have returned promising results. 85Sr was used in place of 90Sr as it is easier to work with, yet still exhibits the same behaviour in terms of sorption. Although some previous studies have looked at the sorption properties of these two radionuclides within the two environments studied most have focussed on only one or two variables. In these studies conducted at Loughborough University, numerous variables including pH, ionic strength and the effect of competing ions being present in the system have been investigated, while all the time keeping the remaining contributing variables, (all of those not being specifically investigated, plus contact time, solid-to-liquid ratio etc) constant. This has provided data which will be extremely valuable as any changes in behaviour can be directly associated with the altered variable and results can be directly compared with those previously obtained.
The rheology of clays and clay minerals plays an important role in the transport of these key radionuclides. A key area of the repository LTP (Life Time Plan), for research and development is to be able to link the transport in the materials studied to rheology and organic content. Specific clays of interest are bentonite and montmorillonite, as well as the mineral brucite. A final goal of being able to inhibit transport, either by chemical speciation or barrier systems is an aim of this project.
Study of cesium and strontium sorption on Rokle bentonite in different electrolytes20m
Sorption of radionuclides on bentonite represents in most of deep geological repository (DGR) concepts important process retarding radionuclide migration into geosphere. In the Czech Republic, DGR concept takes local bentonite into account as material for both buffer and backfill. The candidate bentonite comes from the Rokle deposit (NW Bohemia) and represents complex mixture of (Ca,Mg)-Fe-rich montmorillonite, micas, kaolinite and other mineral admixtures (mainly Ca, Mg, Fe carbonates, feldspars and iron oxides). This bentonite is different in composition and properties from worldwide studied Na-bentonite (e.g. MX-80, Volclay) or Na-Ca bentonite (e.g. Febex). This fact leads to the need of investigation of Rokle bentonite in greater detail to verify its suitability as a buffer and backfill in DGR.
Despite a number of studies concerning cesium sorption on bentonites, there are still some issues requiring clarification, especially the effect of cesium-selective minerals (micas and mica-type clay minerals). Their amount in bentonite and their effect on cesium sorption at different conditions represents great uncertainty in cesium sorption evaluation. In this study, the general trends of cesium and strontium sorption on Rokle bentonite (different samples) in comparison to well-defined reference material (Ca-montmorillonite SAz-1) were compared. Then, the effect of changing solution ionic composition on both Cs and Sr sorption was investigated in detail for average sample of Rokle bentonite and associated uncertainties in distribution coefficient (Kd) determination were evaluated.
The comparison with reference sample demonstrates that cesium-selective minerals are very important for cesium sorption even at its trace concentrations. For strontium there are no selective minerals to sorb it and the sorption is influenced mainly by the cation exchange capacity (CEC) of the bentonite. Comparing different electrolytes for cesium, the potassium has the highest competitive effect (competition on selective sites), in contrast to sodium and calcium. For strontium, the calcium has the highest competitive effect (competition on regular ion exchange sites), then the potassium and the last one the sodium. No significant differences were found for three selected samples of Rokle bentonite in sorption behavior for cesium and strontium, except the effect of total CEC of bentonite.
The main uncertainty sources for cesium arise from the presence of cesium-selective minerals in Rokle bentonite samples in varying amount. For strontium, the amount of smectite (which has the highest CEC in natural bentonite) represents the main source of uncertainties. It also follows from the performed experiments that the cesium sorption on studied bentonite cannot be described using simple Kd value.
(Nuclear Research Institute)