Influence of Dissolved Hydrogen on Oxide Film and PWSCC of Alloy 600 in PWR Primary Water

摘要

In order to investigate the influence of dissolved hydrogen on the oxide film and primary water stress corrosion cracking (PWSCC) of Alloy 600 in primary water of PWR under actual operating temperature range, electrochemical polarization measurement, analysis of the oxide film on the alloy and PWSCC test were carried out. In all cases, the content of dissolved hydrogen was changed from 0 to 45 cc/kg H_2O. The anodic polarization curve reveals that the peak current density increases with increasing dissolved hydrogen and the change of the peak current density becomes maximum between 11 and 30 cc/kg H_2O of dissolved hydrogen. According to the results of oxide film analysis, it is seen that the oxide films formed below 11 cc/kg H_2O of dissolved hydrogen are relatively thick and rich in Ni, but those formed at higher dissolved hydrogen content are relatively thin and rich in Cr and Fe. The susceptibility of the alloy to PWSCC has a peak at 11 cc/kg H_2O of dissolved hydrogen, which reveals that the property of the oxide film may play important role in PWSCC of alloy.