Thermal Transport in Off-Stoichiometric Uranium Dioxide by Atomic Level Simulation

The thermal conductivity of hypo- and hyperstoichiometric UO(2) is calculated as a function of defect concentration and temperature using the direct method in molecular dynamics simulations. Anion defects, the dominant defects in UO(2), are shown to significantly influence the thermal conductivity. Lattice dynamics calculations show how this reduction arises from changes in the nature of the lattice vibrations, as characterized by the polarization vectors and participation ratios. In addition, (235)U isotopic defects are shown to have a negligible influence on the thermal conductivity