SCC of Austenitic Stainless Steels Under Off-Normal Water Chemistry and Surface Conditions

Abstract

The field experience of austenitic stainless steels in PWR (Pressurized Water Reactor) primary circuits has been generally outstanding. However, the effect of so called “off normal” conditions still plays an important role regarding the SCC (Stress Corrosion Cracking) susceptibility of austenitic stainless steels (SS). Such off normal conditions can either be surface conditions or off normal water chemistry conditions, which is the topic of this paper. This paper summarizes evaluations of the SCC susceptibility of cold worked stainless steels in off normal oxygenated environment including transients. In order to study off normal chemistry conditions, SCC tests were performed in simulated PWR primary water conditions under either hydrogen water chemistry conditions or oxygenated conditions. Since the effect of transients are suspected to play a role under plant conditions, additional tests were performed with continuously changing from oxygenated to hydrogenated conditions and compared to results from tests under purely hydrogenated or oxygenated water chemistry conditions.