Thermodynamic assessment of the LiF–NaF–ThF4–UF4 system

Abstract The present study describes the full thermodynamic assessment of the LiF–NaF–BeF 2 –ThF 4 –UF 4 system which is one of the key systems considered for a molten salt reactor fuel. The work is an extension of the previously assessed LiF–NaF–ThF 4 –UF 4 system with addition of BeF 2 which is characterized by very low neutron capture cross section and a relatively low melting point. To extend the database the binary BeF 2 –ThF 4 and BeF 2 –UF 4 systems were optimized and the novel data were used for the thermodynamic assessment of BeF 2 containing ternary systems for which experimental data exist in the literature. The obtained database is used to optimize the molten salt reactor fuel composition and to assess its properties with the emphasis on the melting behaviour.