Molecular dynamics simulations of thermal conductivity of UO₂, PuCrO₃ and PuAlO₃

Full text: The thermal conductivities of the PuCrO₃ and PuAlO₃ precipitates in UO₂ fuel have been calculated using non-equilibrium molecular dynamics simulations. The PuCrO₃ phase showed a markedly lower thermal conductivity than UO₂, which will impact the microstructure, fission product distribution and gas release properties of UO₂-based fuels. The PuAlO₃, in both its orthorhombic and rhombohedral structures, showed greater thermal conductivity in comparison to PuCrO₃, lower than UO₂ at low temperatures but higher at elevated temperatures. Additions of Al with Cr to doped fuels is therefore likely to have a beneficial impact on the thermal conductivity of the fuel as opposed to solely doping with Cr. (author)