On the role of oxygen partial pressure on the composition of the oxide layer formed on alloy 690 at 700°C

Abstract : Steam generator tubes in pressurized water reactors (PWR) are made of nickel based alloy such as alloy 600 or alloy 690. During oxidation process of this alloy in water at high temperature, nickel cations are released in the primary media. After neutron flux exposure in the reactor core, these cations can turn into radioactive products, such as 58Co. If carried through the primary circuit, these radioactive products precipitate and contaminate the loop, making maintenance more difficult.