Separation of NdF₃ using precipitation-distillation coupled method in FLiNaK molten salt

Abstract Background: Low pressure distillation is a promising technology for the recovery and purification of carrier salts (LiF-BeF₂) in the thorium based molten salt reactors (TMSR). Purpose: This study aims to compare the separation behavior of NdF₃ before and after adding the oxidant CaO in FLiNaK molten salt. Methods: Precipitation-distillation coupled method was employed in purification of molten salt. Then the X-ray Diffraction(XRD) was applied to the analysis of the produced NdF₃ in the molten salt. Results: At high temperature, CaO was confirmed to react with NdF₃ and form rare earth oxide Nd₂O₃ insoluble in molten salt. At 730 ℃, the conversion rate for Nd was up to 95%. After the precipitation reaction, the separation rate under low pressure distillation was compared with the preceding one. The decontamination factor of Nd was deduced to 9.4 × 10⁵ whilst the value was 3.1 × 10⁴ without adding CaO. Meanwhile, the evaporation rate also was improved after precipitation. Conclusion: The combination of the precipitation and distillation treatment is an effective way to achieve the high throughput performance in the salt separation process. (authors)