DEVELOPMENT OF AN ANISOTROPIC MECHANICAL MODEL FOR FROBA CODE AND ITS APPLICATIONS FOR SIC COMPOSITE CLADDING ANALYSIS

Abstract

Silicon carbide (SiC) has been considered as one of the promising Accident Tolerant Fuel (ATF) cladding materials. The multi-layer cladding designs consisting of both monolithic SiC(mSiC) and SiC fiber/SiC matrix composites (SiCf/SiC) have been considered as a candidate for light water reactors, meeting the engineering requirements of safety improvement. A twodimensional axisymmetric mechanical model with anisotropic material properties was developed and integrated into the fuel performance code FROBA. The developed mechanical model was solved through the finite difference method and can be employed to analyze both inter-layer interaction and pelletcladding mechanical interaction (PCMI) of anisotropic multilayer claddings. Mechanical performance and failure probability of SiC cladding fuel during normal operation was then simulated. The results suggest that during steady-state operation, SiC cladding show a higher fuel temperature, no PCMI occurs during operation, the hoop stress is in safety level, and the cladding remains integrity.