Process optimization of a closed-chamber distillation system for the recovery of FLiNaK molten salt


Low-pressure distillation has been proposed as a suitable technique for the recovery of carrier salt from molten salt reactor spent fuel. A closed-chamber distillation system, in which the pump is stopped and pressure-induced salt distillation is performed, was arranged for fluoride salt treatment. A stair-step optimization process was demonstrated to improve the recovery efficiency by up to 99%. The pressure change curve was feasible for estimating the distillation process, and a method for displaying the pressure value online in order to determine the end-point was also developed. The decontamination factor of Nd in the condensate salt was deduced to be greater than 100 with 1 wt% NdF3–FLiNaK distillation. The optimal conditions developed in this study showed a high recovery ratio for the fluoride carrier salt and a high separation efficiency for rare earth products.

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Author information




Qiang Dou and Qing-Nuan Li contributed to the study conception and design. Material preparation was performed by Jun-Xia Geng. Data collection was performed by Yang Yang. Data analysis was performed by Yan Luo. The first draft of the manuscript was written by Hai-Ying Fu, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Hai-Ying Fu or Qiang Dou.

Additional information

This work was financially supported by the National Natural Science Foundation of China (No. 21771188) and the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA02030000). A study on some key issues regarding the Th-U fuel cycle was also funded (No. QYZDY-SSW-JSC016).

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Geng, JX., Yang, Y., Fu, HY. et al. Process optimization of a closed-chamber distillation system for the recovery of FLiNaK molten salt. NUCL SCI TECH 32, 3 (2021).

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  • Low-pressure distillation
  • Closed chamber
  • Fluoride molten salt
  • Recovery ratio