Theoretical prediction of KF-RbF-CsF-BeF2 system: phase diagrams calculation and ab initio molecular dynamics

Contains molten salt composition and data files related to phase diagram calculations, as well as detailed analysis result files for ab initio molecular dynamics calculations. Thermodynamic optimization of the AF-BeF2 (A = K, Rb, and Cs), KF-CsF, and RbF-CsF systems was performed within the framework of phase diagrams calculation. The model parameters were optimized based on experimental data and theoretically calculated values. The results show that the thermodynamically calculated values for the AF-BeF2 (A = K, Rb, and Cs), KF-CsF, and RbF-CsF systems agree well with the experimental data. Next, a set of reliable and self-consistent thermodynamic databases was built, and the liquidus projections and invariant points of the sub-ternary systems of the KF-RbF-CsF-BeF2 system were calculated. Furthermore, the melting temperature with the corresponding composition was predicted using the phase diagrams calculation technique, and the radial distribution functions, coordination numbers, angular distribution functions, and diffusion coefficients of the quaternary KF-RbF-CsF-BeF2 system were calculated using ab initio molecular dynamics. The results show that the quaternary KF-RbF-CsF-BeF2 system with the proportion 3.50-28.92-21.78-45.80 mol% or 1.80-35.42-52.40-10.38 mol% is one of the most promising candidate coolants for molten salt reactors in terms of thermodynamics and kinetics. This work provides direct guidelines for the screening and optimization of molten salts in the nuclear energy field.