Determination of eutectic composition and heat capacities of fuel salt (LiF-ThF₄-UF₄) and blanket salt (LiF-ThF₄) mixtures

Fuel salt (LiF-ThF₄-UF₄) and blanket salt (LiF-ThF₄) mixtures in the composition ranges UF₄ (2-3 mole %), ThF₄ (20-22 mole %), LiF (77-78 mole %) and ThF₄ (22.5 mole %), LiF (77.5 mole %), respectively have been synthesized and characterized XRD and thermal techniques. The eutectic melting composition and the liquidus phase boundaries in the selected ranges of composition have been determined from DTA measurements. The enthalpy of fusion of the eutectic fuel salt and blanket salt mixtures was determined by DCS measurements. The enthalpy increments for eutectic composition for fuel salt and blanket salt mixtures have been measured employing a high temperature Calvet calorimeter in solid and liquid ranges. The standard molar heat capacities of eutectic composition for fuel salt and blanket salt mixtures in solid and liquid ranges derived from the enthalpy increment values are found to be C_p, m^o (Fuel salt, s) (JK^-1g^-1) = 1.0355 -2.866.10^-4T-40504/T²(527 < T/K <833 ), C_p, m^o (Fuel salt, l) (JK^-1g^-1) = 0.8234 -2.8152.10^-4T-153419/T² (853< T/K < 1090) and C_p, m^o (Blanket salt, s) (JK^-1g^-1) = 1.02 -2.4619.10^-4T-42324/T² (324 < T/K <833), C_p, m^o (Blanket salt, l) (JK^-1g^-1) = 0.81 -1.244.10^-4T-68388/T² (853< T/K < 1090) respectively. (author)