Characteristics of Oxide Films Formed on Ni-base Alloy Cladding in Deaerated and Hydrogenated High Temperature Water Environment

The characteristics of oxide films formed on Ni-base alloy cladding in simulated pressurized water reactor primary water environments were studied. The oxide films formed in deaerated (dissolved oxygen concentration <5 μg/L) and hydrogenated (dissolved hydrogen concentration was 2.6 mg/L) water environments were compared. The results showed that after immersion at 325℃ for 146 h, oxide particles distributed on the surface of nickel-base alloy sparsely in deaerated water, while in hydrogenated water there was only a dark oxide film without significant outer layer oxide particles. In hydrogenated water, the closer to the overlaying layer-matrix fusion line in the thickness direction of the weld layer, the denser the oxide partides on the surface of the nickel-base alloy, and the higher the oxygen content. The correlation between the material properties in the cladding transition zone and the oxide film properties formed in high temperature water existed.