URANIUM TRANSPORT TO SOLID ELECTRODES IN PYROCHEMICAL REPROCESSING OF NUCLEAR-FUEL

A unique pyrochemical process is being developed for separation of metallic nuclear fuel from fission products by electrotransport through molten LiCl-KCl eutectic salt to solid and liquid metal cathodes. The process will allow recovery and reuse of essentially all of the actinides in spent fuel from the integral fast reactor (IFR) and disposal of wastes in satisfactory forms. Electrotransport is used to minimize reagent consumption and, consequently, waste volume. In particular, electrotransport to solid cathodes is used for recovery of an essentially pure uranium product in the presence of other actinides; removal of pure uranium is used to adjust the electrolyte composition in preparation for recovery of a plutonium-rich mixture with uranium in liquid cadmium cathodes. This paper presents (i) experiments that delineate the behavior of key actinide and rare-earth elements during electrotransport to a solid electrode over a useful range of PuCl3/UCl3 ratios in the electrolyte, (ii) a thermodynamic basis for that behavior, and (iii) a comparison of the observed behavior with that calculated from a thermodynamic model. This work clearly establishes that recovery of nearly pure uranium can be a key step in the overall pyrochemical-fuel-processing strategy for the IFR.