Thermal Conductivity Coefficients of FLiNaK Melt with Lanthanide and Actinide Fluoride Additives: A Molecular Dynamic Study

Molten fluoride salts are used in a molten salt reactor, the main advantage of which is the ability to "burn up" minor actinides such as americium, neptunium, and curium. The thermal conductivity of molten salts is an important thermophysical property that directly affects the efficiency and economic feasibility in the design and development of high-temperature thermal energy installations. In this work, the temperature dependence of the thermal conductivity and density of molten FLiNaK, containing additives of PuF₃, AmF₃, and NdF₃, was calculated using molecular dynamics. The thermal conductivity was determined using the Green–Kubo and Müller-Plathe methods. A negative linear trend was found in the temperature dependence of density, while a predominantly similar trend in thermal conductivity was also established. The density of the systems increases linearly with the concentration of the introduced additives. According to the thermal conductivity calculations using the Green–Kubo method, at high concentrations, the NdF₃ additive can act as an imitator for PuF₃. However, reducing the concentration of PuF₃ decreases the reliability of such a representation.