Multiphysics analysis of thorium-based fuel performance with a two-layer SiC cladding under normal operating and transient conditions in a light water reactor

Due to the excellent properties of high temperature strength, creep resistance, lower thermal expansion and better irradiation resistance, the silicon carbide is considered as a substitute for the Zircalloy cladding. In this paper, the thermal and mechanical properties of SiC cladding are reviewed firstly. Then the thermophysical properties and mechanical behavior model of the thorium-based fuel and SiC cladding are implemented in FRAPCON-4.0 and FRAPTRAN-1.5 codes. Lastly, the fuel performance of five different types of fuel cladding combinations including two kinds of thorium-based fuel, traditional UO₂ fuel and two kinds of cladding (Zircalloy and two-layer SiC) are analyzed and compared both under the PWR normal operating condition and transient conditions. The results show that under normal or transient conditions, the thorium-based fuel with two-layer SiC cladding is found to have higher safety margin and superior fuel performance than that of the fuels combined with Zircalloy cladding.