Separation of CsCl and SrCl2 from a ternary CsCl-SrCl2-LiCl via a zone refining process for waste salt minimization of pyroprocessing

Abstract

The purification of LiCl salt mixture has traditionally been carried out by a melt crystallization process. To improve the throughput of zone refining, three heaters were installed in the zone refiner. The zone refining method was used to grow pure LiCl salt ingots from LiCl-CsCl-SrCl2 salt mixture. The main investigated parameters were the heater speed and the number of passes. A change in the LiCl crystal grain size was observed according to the horizontal direction. From each zone refined salt ingot, samples were collected horizontally. To analyze the concentrations of Sr and Cs, an inductively coupled plasma optical emission spectrometer and inductively coupled plasma mass spectrometer were used, respectively. The experimental results show that Sr and Cs concentrations at the initial region of the ingot were low and reached their peak at the final freezing region of the salt ingot. Concentration results of zone refined salt were compared with theoretical results yielded by the proposed model to validate its predictions. The keff of Sr and Cs were 0.13 and 0.11, respectively. The decontamination factors of Sr and Cs were 450 and 1650, respectively.