Quantification of the risk reduction due to the implementation of ATF claddings in Total Loss of Feedwater sequences

This study quantifies the risk reduction associated with implementing Accident Tolerant Fuel (ATF) cladding in three-loop Pressurized Water Reactors PWR under Total Loss of Feedwater scenarios. The Integrated Safety Assessment (ISA) methodology was applied to evaluate the performance of various ATF claddings, including FeCrAl and Cr-coated Zry, in comparison to the conventional Optimized ZIRLO cladding. The results show that ATF claddings extend the time available for Main Control Room crew intervention, which is crucial for accident mitigation. The analysis highlights the importance of considering cladding oxidation at high temperatures and the ballooning and burst phenomena, particularly in Zry and Cr-coated Zry, to accurately assess the benefits obtained from the ATF implementation.