Multiphysics modeling of thorium-based fuel performance with a two-layer SiC cladding in a light water reactor

Abstract

The performance of thorium-based mixed oxide fuel ((Th,U)O2 fuel and (Th,Pu)O2 fuel) with a two-layer SiC cladding in a light water reactor have been investigated by finite element multiphysics modeling method. The material properties of specific thorium-based Th0.923U0.077O2 fuel, Th0.923Pu0.077O2 fuel and SiC cladding were firstly reviewed and implemented into the multiphysics model. Then the performance of Th0.923U0.077O2 fuel, Th0.923Pu0.077O2 fuel and UO2 fuel separately combined with Zircaloy cladding and two-layer SiC cladding have been investigated and compared under PWR normal operation conditions. Finally, the thorium-based fuel with Zircaloy cladding was found to decrease the fuel centerline temperature, especially for the Th0.923U0.077O2 fuel, but with a much earlier gap closure time. And the two-layer SiC cladding was found to effectively mitigate the pellet-cladding mechanical interaction (PCMI) but also greatly increase the fuel centerline temperature. So the combination of the thorium-based fuel with two-layer SiC cladding is expected to improve the reactor safety by keeping a moderate fuel centerline temperature and meanwhile greatly delaying the PCMI time.