Stress Corrosion Cracking of High-Strength Ni-Base Alloys in PWR Primary Water Containing KOH vs. LiOH

ABSTRACT The stress corrosion cracking behavior of high-strength Ni-base Alloy X-750 and Alloy 718 has been investigated to assess the effect of replacing LiOH with KOH as the pH moderator in pressurized water reactor (PWR) primary circuit coolant. The SCC initiation behavior of X-750 was evaluated by multi-tensile specimen constant load test in either LiOH- or KOH- containing PWR primary water. The SCC growth behavior of X-750 and Alloy 718 was evaluated on compact tension specimens with on-the-fly changes between LiOH- and KOH-containing water in three different PWR primary water chemistries. Direct current potential drop technique was used for in-situ monitoring of crack initiation time and crack extension in SCC initiation and propagation tests, respectively. The results suggest no significant effect of KOH vs. LiOH on the SCC initiation or propagation of the tested materials.