SiC composite claddings: LWR performance optimization for nominal and accident conditions

The Fukushima Daiichi event in 2011 demonstrated the need for enhanced nuclear energy safety, becoming a major driving force for global investments in accident-tolerant fuels (ATFs) over the past decade. Candidate ATF cladding material concepts that are being developed in replacement of the standard zirconium-based alloy (zircaloy) fuel cladding materials used in light water reactors (LWRs) must outperform commercial zircaloys under nominal operation, high-temperature transient (1200°C) conditions. SiC/SiC composites are a rather revolutionary ATF cladding material concept exhibiting inherent refractoriness, pseudo-ductility, and a lack of accelerated oxidation during a loss-of-coolant scenario. Due to their unique potential in meeting the stringent property requirements of the ATF cladding application, SiC/SiC composites have already claimed large global investments. Despite these investments, all state-of-the-art variants of the SiC/SiC composite cladding material concept must still overcome inherent shortcomings prior to their perspective deployment. Two important weaknesses are their inadequate compatibility with the coolant (water and steam) and the early (