Oxidation of high burnup fuel cladding in LOCA conditions

Chuto, Toshinori

In order to investigate effect of burnup on high temperature oxidation of the advanced cladding alloy, isothermal oxidation test was performed with specimens prepared from high burnup fuel cladding which were irradiated up to 79 MWd/kg as well as non-irradiated cladding. Oxidation kinetics was evaluated from weight gain and oxide layer growth. Growth of the inner surface oxide layer formed in the irradiated cladding is almost equivalent to that in the non-irradiated cladding, while growth of the outer surface oxide layer is slightly smaller in the irradiated cladding. It is considered that the oxidation at the outer surface is suppressed by the pre-formed corrosion layer. Results of the weight gain measurement also suggest lower oxidation rates in the irradiated cladding. Consequently, it is concluded that high-burnup effect on high temperature oxidation is small for the examined range, though pre-formed corrosion layer may have the protective effect.