Thermal Transport in Defective Actinide Oxides

Abstract

The present study employs a molecular dynamics simulation to explore thermal transport in various oxide nuclear fuels with defects such as uranium oxide and plutonium oxide. In particular, the effect of vacancy and substitutional defects on the thermal transport in actinide oxides are investigated. It is found that the thermal conductivities of these oxide nuclear fuels are significantly reduced by the presence of vacancy defects. In spite of their small size, oxygen vacancy is shown to alter the thermal conductivity of oxide fuels greatly; 0.1% oxygen vacancy reduces the thermal conductivity of plutonium dioxide by more than 10% when the number of unit cell in length is 100. It was shown that the missing of larger atoms alters the thermal conductivity of actinide oxides more significantly. For the case of uranium dioxide, 0.1% uranium vacancies decrease the thermal conductivity by 24.6% while the same concentration of oxygen vacancies decreases the thermal conductivity of uranium dioxide by 19.4%. However, the uranium substitutional defects are shown to have a minimal effect on the thermal conductivity of plutonium dioxide because of the small change in the atomic mass.