Thermodynamic evaluation on chemical reaction between UO and SiC in LWR conditions

Shirasu, Noriko  ; Kurata, Masaki 

After Fukushima Daiichi nuclear accident in 2011, enhancing the accident tolerance of light water reactor fuels became a very important issue and currently the development of accident-tolerant fuel (ATF) are in progress. SiC is an attractive candidate of ATF cladding material because of its high chemical stability, high radiation resistance and low neutron absorption. SiC reacts much less than Zircaloy with steam, the generation of heat and hydrogen gas would be extremely suppressed. Thermodynamic evaluation on chemical interactions between UO and SiC were performed on various possible conditions of oxygen potential and temperature in severe accident. SiC is converted to SiO by reaction with O. SiC is also converted to SiO by reaction with HO. However, the fraction of the sub-reaction for forming SiO increases than in the case of reaction with O when comparing the results at the same temperatures and the same oxygen potentials.