Transient fuel behavior analysis of UN fuel with a two-layered SiC cladding based on multiphysics method

Abstract

Recently, UN fuel has emerged as a promising alternative to UO2 fuel due to its exceptional thermophysical attributes, including heightened thermal conductivity, elevated melting point, and increased fissile density. Meanwhile, SiC is recognized as a member of the next generation of accident-tolerant cladding materials owing to its impressive strength at high temperatures, resistance to creep, minimal thermal expansion, and improved irradiation characteristics. In this study, utilizing our developed fuel performance analysis code CAMPUS, we integrate a multiphysics model featuring UO2 fuel paired with a two-layered SiC cladding into the CAMPUS framework. Subsequently, we conduct simulations and analyses of the fuel performance for combinations such as UO2-two-layered SiC, UN-two-layered SiC, UN-Zircaloy, and UO2-Zircaloy. These evaluations encompass both standard operation scenarios and potential accident conditions within a pressurized water reactor (PWR). Notably, the incorporation of UN fuel demonstrates a significant reduction in maximum fuel temperature during normal operation, as well as under Loss-of-Coolant Accident (LOCA) and Reactivity Initiated Accident (RIA) conditions. However, upon introducing the two-layered SiC cladding, it becomes apparent that its temperature performance is somewhat inferior to that of Zircaloy under normal operation and RIA scenarios. Conversely, when subjected to a LOCA scenario, the thermal and mechanical characteristics of the two-layered SiC cladding outperform those of the Zircaloy cladding.