Speaker
Description
Future nuclear fuel cycles based on fast reactors are being developed in many countries. New nuclear fuel cycles include the reduction of long term radiotoxicity of nuclear waste by partitioning and transmutation of long lived transplutonium elements. So the selective recovery of transuranium elements, especially actinides (III) – americium and curium, from the high lever radioactive waste (HLW) created by the reprocessing of spent nuclear fuel is rather actual problem.
Liquid-liquid extraction is one of the known and proven methods of separation of the actinides (III) from PUREX rafinates. Some isotopes of americium and curium are strong α-emitters and the solvents, used for the partitioning of HLW are exposed to α-particles emitted by the isotopes along with β- and γ-radiation emitted by fission products.
We have developed a process, using a solvent based on well-known ligand N,N,N’,N’-tetraoctyldiglycolamide (TODGA) [1] in polar diluent meta-nitrobenzotriflourite (F-3) [2]. Such diluent significantly increases the capacity of solvent in comparison with traditional hydrocarbons and prevents the third phase formation [3].
But this diluent contains flourine atoms so the fluoride ions can be produced as a result of degradation of the F-3 under irradiation. The fluoride ions can significantly increase the corrosion rate of steel. In case of evaporation of the solutions created by reprocessing of HLW, the high concentrations of fluoride ions can lead to very serious problems.
In this work the effect of α-, β-, γ- irradiation of the solvent on yield of fluoride ions was studied. The yield of fluoride ions was not very significant. G-value for yield of fluoride ions – about 2 ions / 100 eV under α- irradiation, about 0,7 ions / 100 eV under γ- irradiation and about 0,67 ions / 100 eV under β- irradiation.
The system shown good resistant extractions properties and slight G-value of fluoride ions.
Reference
1. Sasaki, Y.; Sugo, Y.; Suzuki, S.; Tachimori, S. The novel extractants, diglycolamides, for the extraction of lanthanides and actinides in HNO3–n-dodecane system. Solvent Extr. Ion Exch. 2001, 19, 91.
2. M.Yu. Alyapyshev, V. A. Babain, E.V. Kenf, L. Tkachenko, M.V. LogunovYu.A. Voroshilov, R.N. Khasanov, A.Y.u. Shadrin, V.L. Vidanov / Patent RU 2603405 С1, 27.11.2016;
3. M. Alyapyshev, V. Babain, I. Eliseev, E. Kenf, L. Tkachenko / New polar fluorinated diluents for diamide extractants // J. of Radioanalytical and Nuclear Chemistry, 2016, 310(2), 785-792.
