Thermal-Mechanical performance analysis of a petal-shaped fuel rod under RIA condition

This paper establishes the performance analysis model of a petal-shaped fuel rod (PSFR) under Reactivity Initiated Accident (RIA) condition based on thermal elastic-plastic theory and finite element method. The results show that the temperature changes of fuel and cladding are basically synchronized, and the temperature extremes appear in the central region, with the distribution characterized by a large middle and two small sides. The stress is concentrated in the center region of the cladding. At the beginning of operation, the stress at the lobe root of cladding is the largest. With the increase of operation time, the stress concentration at the lobe tip is gradually obvious. At 150th days of operation, a sudden RIA occurred and the power factor of the PSFR rapidly increased over 5.38 times and the cladding stress exceeded the yield strength. The axial and circumferential center cladding lobe roots and nearby may be at greater risk of plastic deformation. These results will provide an important theoretical basis for the determination of the deformation and accident operation risk of PSFRs.