Computational framework for thermal conductivity and volumetric swelling of irradiated silicon carbide

Defect production and accumulation in SiC has been studied by molecular dynamics (MD) simulations, and a kinetic model has been developed for defect evolution in SiC in the temperature regime of 473 K to 1073 K. Simulations show that the increase in irradiation temperature diminishes the defect production efficiency of SiC and suppresses the defect accumulation. Thermal conductivity and swelling calculated by the model show good agreement with isothermal irradiation experiments. Evolution of thermal conductivity and swelling under varying temperature shows that the current model can overcome the drawback of isothermal models in terms of unphysical concurrent evolution with temperature during short transient. Thermo-mechanical analysis of SiC cladding under typical LWR loading conditions reveals that the proposed model and the existing models predict similar stress distribution and evolution under steady power, while the stress is underestimated during reactor shutdown/power ramp-down and overestimated during power ramp-up by the previous isothermal model. The results indicate that the proposed model can be applied to the fuel performance analysis especially for cases with abrupt temperature changes such as reactor shutdown and power ramp.