Full-core normal and preliminary transient analysis for SiC-based rod designs

When introducing a new fuel concept in traditional light water reactors (LWRs), analyzing its performance under a variety of power histories while attempting to simulate its stress state as realistic as possible is desired. By having access to such capability, the fuel developer can assess the safety characteristics of the new fuel concept and optimize its design performance. SiC/SiC Ceramic Matrix Composite (CMC) with chemically vapor deposited (CVD) SiC, is an accident tolerant fuel (ATF) concept owing to its high mechanical strength and remarkably enhanced oxidation-resistance. The modeling of SiC cladding requires capability to simulate multilayers and capture the nonlinear response of SiC material under neutron radiation. In addition, considering its probabilistic failure characteristics, efficient running fuel performance tools are required to assess its initial safety performance and optimize its design. In this work, we added a multi-layer deformation model in FRAPCON-4.0 and FRAPTRAN-2.0, with the primary motivation to analyze the performance of SiC cladding for UO2, annular UO2 and U3Si2 fuels from a full core point-of-view. We then performed reactivity-initiated accident (RIA) and loss-of-coolant accident (LOCA) for the limiting rod. During normal conditions, the failure risk of SiC cladding is mainly determined by pellet-cladding mechanical interaction (PCMI) and U3Si2 is a more promising fuel compared to UO2. While promising performance was simulated during LOCA for all fuels, during RIA, U3Si2 performance was found to be likely more limiting compared to UO2. Results show that the full core simulation methods developed for this work are robust and computationally efficient and can be adopted for other ATF design analysis.