Transient fuel performance analysis of UO₂–BeO fuel with composite SiC coated with Cr cladding based on multiphysics method

The transient multiphysics models were updated in CAMPUS to evaluate the accident-tolerant fuel performance under accident conditions. CAMPUS is a fuel performance code developed based on COMSOL. The simulated results of the UO₂–Zircaloy fuel performance under accident conditions were compared with those of the FRAPTRAN code and the experimental data to verify the correctness of the updated CAMPUS. Subsequently, multiphysics models of the UO₂–BeO fuel and composite SiC coated with Cr (SiC_f/SiC-Cr) cladding were implemented in CAMPUS. Finally, the fuel performance of the three types of fuel cladding systems under Loss of Coolant Accident (LOCA) and Reactivity Insertion Accident (RIA) conditions was evaluated and compared, including the temperature distribution, stress distribution, pressure evolution, and cladding failure time. The results showed that the fuel temperature of the UO₂ fuel under accident conditions without pre-irradiation was lower after being combined with SiC_f/SiC-Cr cladding. Moreover, the centerline and outer surface temperatures of the UO₂–BeO fuel combined with SiC_f/SiC-Cr cladding reduced further under accident conditions. The cladding temperature increased after the combination with the SiC_f/SiC-Cr cladding under accident conditions with pre-irradiation. In addition, the use of SiC_f/SiC-Cr cladding significantly reduced the cladding hoop strain and plenum pressure.