Integrating a multi-layer deformation model in FRAPTRAN for accident Tolerant fuel analysis

Abstract Fuel performance analysis capability is needed to assess proposed Accident Tolerant Fuel (ATF) designs. In this work, a deformation model was implemented in FRAPTRAN 2.0 to model a multi-layer ATF concept during both reactivity-initiated accident (RIA) and loss-of-coolant accident (LOCA). The modified FRAPTRAN (M−FRAPTRAN) performance was assessed against limited UO2-Zircaloy validation database and the performance was found to be comparable to FRAPTRAN 2.0 and experimental data. Finally, in order to demonstrate the added capabilities in M−FRAPTRAN, two-layer SiC clad design consisting of SiC/SiC ceramic matrix composite (CMC) and monolithic SiC (mSiC) was modeled. During RIA, the onset of pellet clad mechanical interaction can significantly raise the mSiC principal stresses. During LOCA, the SiC potential annealing behavior (recovery of swelling strain) has a significant influence on cladding stress distribution and outer region of mSiC cladding may undergo tensile stress, which can threaten the leak tightness of the cladding during LOCA.