Multiphysics Modeling of Thorium-Based (Th, U)O₂ and (Th, Pu)O₂ Fuel Performance in a Light Water Reactor

ThO₂ has been considered as a possible replacement for UO₂ fuel for future generation of nuclear reactors, and thorium-based mixed oxide (Th-MOX) fuel performance in a light water reactor was investigated due to better neutronics properties and proliferation resistance compared to conventional UO₂ fuel. In this study, the thermal, mechanical properties of Th_0.923U_0.077O₂ and Th_0.923Pu_0.077O₂ fuel were reviewed with updated properties and compared with UO₂ fuel, and the corresponding fuel performance in a light water reactor under normal operation conditions were also analyzed and compared by using CAMPUS code. The Th_0.923U_0.077O₂ fuel were found to decrease the fuel centerline temperature, while Th_0.923Pu_0.077O₂ fuel was found to have a bit higher fuel centerline temperature than UO₂ fuel at the beginning of fuel burnup, and then much lower fuel centerline than UO₂ fuel at high fuel burnup. The Th_0.923U_0.077O₂ fuel was found to have lowest fuel centerline temperature, fission gas release and plenum pressure. While the Th_0.923Pu_0.077O₂ fuel was found to have earliest gap closure time with much less fission gas release and much lower plenum pressure compared to UO₂ fuel. So the fuel performance could be expected to be improved by applying Th_0.923U_0.077O₂ and Th_0.923Pu_0.077O₂ fuel.