Separation and Solidification of Rare Earth Nuclides from LiCl-KCl Based Eutectic Waste Salts using a series of Phosphorylation/Distillation/Solidification Processes

Abstract

Pyroporcessing of spent nuclear fuel generates a considerable amount of LiCl-KCl eutectic waste salt containing radioactive rare earth (RE) chlorides. In this study, a series of processes, which consist of a phosphorylation/distillation process and a solidification process, were performed to minimize volume of the LiCl-KCl eutectic waste salt and solidify a residual waste into a stable form at a relatively low temperature. Over 99wt% of RE chlorides in LiCl-KCl eutectic salt was converted and separated into REPO 4 in the phosphorylation/distillation process using a mixture of Li 3 PO 4 -K 3 PO 4 . The separated REPO 4 was solidified into a homogeneous and fine-grained form at 1,050℃ using LIP(Lead Iron Phosphate) as a solidification agent. The final waste volume was reduced below about 10% through the series of the processes. stirring rate: 300 rpm, phosphorylation agent: 1 eq.). Fig. 3. XRD patterns of products obtained from phosphorylation and distillation processes (RE: rare earth).