PbSCC OF ALLOY 800NG STEAM GENERATOR TUBING IN ALKALINE ENVIRONMENTS

摘要

Laboratory testing suggest that Alloy 800NG steam generator tubing is susceptible to lead stress corrosion cracking (PbSCC) when exposed to lead contaminated high pH conditions. Assessing the range of pH values where Alloy 800NG is susceptible to PbSCC is important to help understand the range of operating values that need to be maintained to prevent PbSCC from occurring in operating steam generators. In this program, two pH values were used and the PbSCC resistance of Alloy 800NG was measured for Alloy 800NG in the solution annealed (Alloy 800NG) and cold worked (CW Alloy 800NG) conditions in lead contaminated NaCl solutions of pH_(330°C) 8.5 and 9.5 meant to simulate realistic contaminated crevice conditions. Results showed that Alloy 800NG was susceptible to cracking at both pH values, but that at pH_(330°C) 8.5 there was a significant incubation time before the onset of cracking. The results will be used to improve guidance on operation of steam generators utilizing Alloy 800NG tubing.