Comparative study on uncertainty analysis of different accident-tolerant fuels under large-break loss-of-coolant accident

Accident-tolerant fuels (ATFs) can enhance the safety margin of the reactor under an accident scenario and benefit for the normal operation and transient processes of nuclear reactors. This study employs an uncertainty analysis method to systematically evaluate the potential performance advantages of the FeCrAl cladding and UO2_SiC fuel pellets, compared to the conventional UO2-Zr assembly, during a large-break loss-of-coolant accident (LBLOCA) in a 1000 MWe pressurized water reactor. In this study, the peak cladding temperature (PCT) and peak fuel temperature (PFT) were selected as the figures of merit (FOM). Based on the Wilks method and Spearman method, tolerance interval estimation and sensitivity analysis were performed. The evolution trends of the FOM tolerance intervals and sensitivity coefficients over time, as well as the tolerance intervals and sensitivity coefficients corresponding to the maximum FOM, were obtained. Results show that FeCrAl cladding slightly elevates the PFT tolerance limit by 13.5 K but significantly reduces the PCT limit by 80 K. Conversely, UO2_SiC fuel achieves a dual safety benefit by lowering PFT and PCT limits by 294 K and 50 K, respectively. Furthermore, the sensitivity analysis indicate that the type of ATF has a relatively small impact on the sensitivity coefficients. This study offers critical theoretical guidance for the engineering deployment of ATF and the optimization of advanced reactor safety systems.