Dealloying of Monel 400 in nuclear steam generators

Immersion experiments were conducted to evaluate the corrosion performance of commercially available Monel 400 in simulated nuclear steam generator environments. Monel 400 is susceptible to dealloying at open circuit in the presence of Cu 2+ ions, which stabilize metallic copper when present at sufficiently high concentration. A mechanism is proposed for dealloying of Monel 400 in nuclear steam generators due to Cu 2+ accumulation within steam generator sludge piles. • Dealloying of Monel 400 occurs when Cu 2+ ions stabilize metallic Cu. • Sludge piles within steam generators harbour high concentrations of Cu 2+ . • A mechanism for dealloying of Monel 400 in nuclear steam generators is proposed.