Estimation of the enrichment of Cs in molten chloride and fluoride systemsby molecular dynamics simulation

For the pyrochemical reprocessing of spent metallic fuels in molten salt ba ths it is of importance to estimate the enrichment degree of Cs. A molecula r dynamics simulation has been executed on molten (Li, Na, Cs)CI at 900 K a nd (Li, Na, Cs)F at 925 K for various compositions in order to calculate th e relative differences in the internal cation mobilities of Cs in molten Li Cl-NaCl equimolar mixtures and the LiF-NaF eutectic. According to these res ults the self-exchange velocities of Li+, Na+ and Cs+ with respect to Cl- a nd F- have similar tendencies at each composition, and Cs can be enriched e ffectively up to x(Cs) = 0.5 - 0.6 in LiCl-NaCl melts. In addition, the seq uence of the calculated self-diffusion coefficients for various composition s was in a fair agreement with that of the obtained self-exchange velocitie s.