Effect of chloride deposition on stress corrosion cracking of 316L stainless steel used for intermediate level radioactive waste containers

Abstract

This work analysed the effect of chloride deposition on the susceptibility to atmospherically induced stress corrosion cracking (AISCC) of stainless steel type AISI 316L used to manufacture containers for radioactive intermediate level waste in the UK. Using U-bend specimens contaminated with MgCl₂, a threshold deposition for AISCC occurrence has been found above chloride contamination levels of 10 and 25 μg cm⁻² at 50 and 30°C respectively at the equilibrium relative humidity (RH) of the contaminant salt (∼30%RH). Higher contamination levels were required to produce cracking at 60%RH. Based on crack depth data and contaminated area characterisation, it was found that susceptibility to AISCC is affected by the liquid film volume, thickness and continuity.