Condition for Lead-Induced Corrosion of Alloy 690 in an Alkaline Steam Generator Crevice Solution

Abstract The effects of dissolved lead on the anodic dissolution behavior of Alloy 690 (UNS N06690) were experimentally investigated in an alkaline solution that is used to simulate the environment in a nuclear steam generator crevice. Lead inoculation and scratch techniques were applied to exclude the inference of the impact of oxidization of the metallic lead deposit. It has been found that lead deposit can promote transient dissolution on the bare metal surface in the alkaline crevice solution before a fully passive state is achieved. The experimental measurements suggest that the promoted transient dissolution is likely to result from the selected dissolution of nickel. The presence of dissolved lead contamination may retard the passivation or repassivation of the alloy. The effect of lead contamination is very limited on the uniform anodic dissolution of the alloy at stable passive state in the alkaline crevice solution.