Effect of Additive Composition on High Temperature Oxidation Resistance of Pressureless Sintered Silicon Carbide Ceramics for Particle-Based Accident Tolerance Fuel

Silicon carbide (SiC) received considerable attention due to it's a potential for achieving higher safety margins under beyond-design basis accident (BDBA) scenarios. Especially, the Particle-based accident tolerant (PBAT) fuel using SiC is alternative course to overcome the severe accident. The presence of the SiC layer of the TRISO and the dense SiC matrix of ceramic capsule in Particle-PBAT fuel provide two additional barriers to fission product release. Above all, the performance on high temperature oxidation of PBAT fuel is one of important factors for plant safety of nuclear reactors. Given the significant interest in SiC materials for the PBAT fuel, the high temperature oxidation of SiC, especially in the presence of water vapor, has received considerable attention. Sintering method of SiC ceramic matrix for PBAT fuel is liquid phase sintering (LPS) method by additive system. The effect of additive composition on high temperature oxidation of pressureless sintered SiC ceramics for PBAT fuel has been investigated. The high temperature oxidation resistance of LPS-SiC specimens was dependent on the additive content, steam flow rate, and chemistry of the additive composition. More importantly, crystallization of grain boundary is essential factor for oxidation resistance performance of LPS-SiC ceramics. Developed LPS-SiC ceramics with alumina-yttria-calcia additives are very useful for densification and oxidation resistance on matrix material of the PBAT fuel.