Impurities in Primary Coolant Salt of FHRs: Chemistry, Impact, and Removal Methods

The fluoride salt‐cooled high‐temperature reactor (FHR) is one of the Gen. IV reactor concepts. Considering the complexity of salt chemistry, radiation risk, impurity‐induced material corrosion, and impurity‐induced solid precipitation, the salt chemistry should be well controlled. Therefore, molten salt cleanup systems are needed in operation. Based on the experience of molten salt reactors (MSRs) and available data, the present study identifies the types of impurities, their potential sources, and their impact in FHR primary coolants. Cleanup methods for each type of impurity and future research activities are also discussed.