Purification and Separation of Fluoride Molten Salt in Thorium Molten Salt Reactors System by Low Pressure Distillation

Fluoride molten salt has many advantages such as high chemical and radiation stability, high thermal conductivity and heat capacity, low vapor pressure and so on, so it is used as one of the best fuel carrier salts and coolant for the molten salt reactor (MSR). With the development of MSR technique, it is necessary to develop the technique for the recovery and purification of molten salt. The low pressure distillation was studied on the carrier salt recovery, electrolysis product treatment, and graphite fuel ball cleaning. The results show that the decontamination factor for SrF₂ and LaF₃ is 4.4×10³ and 1.9×10³ respectively, and the value for ThF₄ is 94 in FLiNaK salt system. The entrained salt with cathode product after electrolysis is removed by vacuum distillation, and the salt immerged in the graphite ball can also be removed and the removal rate ratio is up to 94%.