Chemical behavior of grey phases in LiCl molten salt for oxide reduction in pyroprocessing

Chemical stabilities of SrZrO 3 , BaZrO 3 , and Sr 0.5 Ba 0.5 ZrO 3 in LiCl molten salt were investigated to evaluate dissolution properties of Sr and Ba in grey phases of spent nuclear fuels during oxide reduction. Sr in SrZrO 3 was partially insoluble in LiCl, even in the presence of metallic Li, while Ba in BaZrO 3 was almost extracted. In contrast, both Sr and Ba in solid-solution phase (Sr 0.5 Ba 0.5 ZrO 3 ) well dissolved in LiCl. Pre-treatment of the spent nuclear fuels before the oxide reduction should be carefully designed to prevent formation of the insoluble Sr-based compounds for efficient Sr separation.