Ab initio molecular dynamics investigation of γ-(U,Zr) structural and thermal properties as a function of temperature and composition

Abstract

Uranium in its metallic form is considered as a fuel for sodium fast reactors due to its higher thermal conductivity and high fissile material density relative to UO2 fuel. The metal is alloyed with zirconium to increase its stability at high temperatures and increase its solidus temperature. This work uses ab initio molecular dynamics to perform an evaluation of the mechanical and thermophysical properties of the γ-(U,Zr) system at temperatures between 1000 K and 1400 K. Among these properties are the equilibrium volume, bulk modulus, molar heat capacity, heat of formation, and the surface energy. The obtained results are compared to experimental data and previous computational work available in the literature. This is the first study of γ-(U,Zr) utilizing ab initio molecular dynamics, and reduces thermophysical property knowledge gaps that are currently present in the literature.