Corrosion evaluation of oxide formed on zircaloy-2 in presence of metal ions

Operation of Pressurized Heavy Water Reactors at high temperature and high pressure generates corrosion products due to the interaction of coolant with carbon steel (CS). Though the CS corrosion is reduced by Fe₃O₄ film, the radioactivity transport problem necessitates further reduction in metal ion release. Metal ion passivation (MIP) method is being used to modify the oxide films to control the corrosion of CS. Electrochemical corrosion studies with the addition of external metal ions (Ni²⁺, Zn²⁺ and Mg²⁺) showed better corrosion protection in presence of zinc and magnesium ferrites compared to magnetite and nickel ferrite. If MIP carried out in PHWRs, the core material Zircaloy-2 (Zr-2) will come in contact with the metal ions in alkaline medium. Hence corrosion resistance evaluation of Zr-2 in presence of Zn²⁺ and Mg²⁺ ions in alkaline medium was carried out by hydrothermal method at 250 °C for 10 days exposure duration