Effect of pre-oxide on Zircaloy-4 high temperature steam oxidation

An experimental study has been carried out on the high temperature oxidation behavior of pre-oxidized Zircaloy-4. Prior to steam oxidation, cladding tubes have in moistened oxygen environment at 425 °C, up pre-oxide layer thicknesses 36 and 63 µm. All samples then subjected isothermal 900 °C-1200 °C range, followed by water-quenching. Metallographic examinations mean hydrogen content measurements performed. For all tested temperatures, weight gains measured for are lower than those obtained bare cladding, indicating that a protective effect against temperature. The results O2+steam good agreement with published data autoclave-pre-oxidized samples. Comparison literature irradiated shows that, 1000 1200 laboratory-grown unirradiated pre-oxidation layers stronger influence corrosion formed under irradiation. This difference protectiveness may be explained more heterogeneous oxide microstructure higher intergranular porosity in-reactor comparison laboratory conditions.