Experimental investigations of thermodynamic properties of the LiF –CsF binary system and FliNaK

Abstract

Generation IV nuclear power technologies, including various molten salt reactor designs are considered to accommodate growing energy needs with minimal impact on the environment. The development of the molten salt reactor class highly depends on understanding molten fluoride salt physicochemical properties, which are studied and verified by reviewing existing data coupled with modern experimental techniques. Experimental investigations of thermodynamic properties of several fluorides were performed to fill knowledge gaps identified in the thermodynamics of fluoride salts. A custom crucible design, selection of suitable calibrants, sample preparation refinement, benchmarking, qualification, and new experimental measurements have been performed. Crucibles worked well for phase transition measurements, benchmarking results gave confidence in developed procedures, capabilities and limitations of the proposed approach were also identified. New measurements of the LiF –CsF system filled some knowledge gaps on the melting behaviour and revealed an additional phase that was not previously reported in the open literature.