Separation of uranium and transuranic elements from rare earth elements by means of multistage extraction in LiCl-KCl/Bi system

A pyrometallurgical partitioning process is being developed for recovering transuranic elements (TRUs) from high-level liquid waste. For estimating the separation efficiencies of TRUs from rare earth elements (REs), preliminary measurements mere made of the distribution coefficients of TRUs in an LiCl-KCl/Bi system at 773 K. Actual separation of TRUs from REs was experimented by multiple-batch extraction in LiCl-KCl/Bi system. The experimental results agreed well with estimates obtained from measured separation factors for single-step reductive extraction. A simulation study was performed in counter-current extraction, for which the TRU recovery yields and separation efficiencies were derived from the measured distribution coefficients. The results indicated that counter-current extraction should permit recovering more than 99% of every actinide contained in the high-level liquid waste, while ensuring a mass ratio of TRUs to REs high enough for deriving metallic fuels for FBR.