Testing of Lead Stress Corrosion Cracking (PbSCC) Inhibitor Candidate

Abstract

Lead Stress Corrosion Cracking (PbSCC) is a form of Stress Corrosion Cracking (SCC) that can be especially aggressive and laboratory testing has shown that alloys such as Alloy 690TT and Alloy 800NG, which are very resistant to cracking in normal operation, are still susceptible to PbSCC in environments which could be encountered in faulted conditions. Therefore, EPRI is investigating the use of a chemical additive, an inhibitor, for secondary side water to act to suppress PbSCC. The recently completed EPRI test program examined the use of production style tube material with a novel direct current potential drop (DCPD) crack monitoring and loading scheme to test samples with a similar material state as those installed in service. Additionally, the testing utilized multiple inhibitor concentrations to understand the effectiveness of concentrations lower than those previously used during inhibitor scoping evaluations presented at previous Environmental Degradation conferences.