An Finite Element Method Study of the Thermal Conductivity of Polycrystalline UO2

Abstract

A finite element method (FEM) is applied to investigate the thermal conductivity of polycrystalline UO2. The influences of microstructure are especially important for UO2 due to the severe structural changes under irradiation conditions. In this study, we have investigated the influences of microstructures on the thermal conductivity of polycrystalline UO2 using FEM. The temperature profile of fuel pellet with different microstructures during service is also investigated. The thermal conductivity increases with increasing grain size. The grain size distribution has obvious influence on the thermal conductivity especially when there are pores in the polycrystal. The influences of porosity and pore size are very sensitive to the position of the pores. The results obtained in this study are useful for the prediction of property changes of UO2 fuel in pile and important to gain some design guidance to tune the properties through the control of the microstructure.