On Water Induced Sensitization of Ni (Fe,Cr) alloys towards Stress Corrosion Cracking in LWR Piping from 1st Principles Modelling

Report, 2021

In Swedish Light Water Reactors (LWR), stress corrosion cracking of reactor components and welds occurs from time to time. As the nuclear power plants are ageing, it is essential to study and further understand the mechanism for environmentally induced sensitization. Natural cracking is a phenomenon that is difcult to predict and very hard to study since it occurs suddenly and often unexpectedly. In order to study the crack initiation and growth, the crack is traditionally experimentally provoked and it is not known to what degree these experimental cracks correspond to those that occur naturally. The environment in an LWR contributes to material ageing through chemical reactions with the environment. An in-depth examination has shown that the microstructures of oxide flms changes along the crack path and the oxide flm in the crack tip is signifcantly diferent from what one detects at the crack opening. In this study, 1st principles modelling is used to articulate an environment induced sensitization mechanism for stress corrosion cracking of Ni(Fe,Cr) alloys in LWR conditions.