Investigation of surface treatment effects on the environmentally-assisted cracking behaviour of Alloy 182 in boiling water reactor environment

Abstract

Surface treatments of primary circuit components in light water reactors are regarded as possible ways to mitigate environmentally-assisted cracking (EAC). To date, it is not fully conclusive which surface condition is suitable to reduce the EAC initiation susceptibility. Constant extension rate tensile (CERT) tests were performed by several labs using flat tapered tensile specimens with different surface conditions (ground, industrial face milled, advanced face milled and shot peened), exposed to a boiling water reactor normal water chemistry environment at 288°C. Despite some scatter in the results, the CERT tests revealed that the EAC initiation susceptibility seems lowest for the advanced face milled surface and highest for the shot peened surface. However, it must be emphasised that the differences were moderate and that the surprising behaviour of the shot peened surface can be explained. The mechanical grinding of the surface did not significantly retard EAC initiation compared to industrial face milling.

Role of Zn Injection on Mitigating Stress Corrosion Cracking Initiation of Alloy 182 Weld Metal in Simulated Light Water Reactor Environment

“…This CERT test method allows a fast and systematic screening of the SCC initiation behaviour with or without Zn injection [18]. It was developed and validated in the framework of several collaborative research projects (MICRIN+ [19] and MEACTOS [20,21]). For each condition (see Section 2.2.3) at least two repeated tests were performed, resulting in four stress threshold data points, which were averaged.…”