Localized Corrosion of Nuclear Grade Alloy 800 Under Steam Generator Layup, Startup and Operating Conditions

Abstract

The localized corrosion resistance of nuclear-grade Alloy 800, which is one of the preferred steam generator (SG) heat exchange tube materials of CANDU and PWR reactors, was studied under simulated SG secondary side crevice chemistry conditions at ambient temperature as well as at elevated temperatures. Series of cyclic potentiodynamic polarization tests were performed to study the localized corrosion resistance of Alloy 800 as a function of chloride ion concentration in the SG crevice solution at 40°C, 150°C and 300°C. Based on the experimental results, empirical equations were provided for calculating the pitting potential of nuclear grade Alloy 800 in the SG secondary side crevice chemistries with different levels of chloride concentration at SG layup, startup and operating temperatures.