Contribution to understanding of stress corrosion cracking of Alloy 600 in PWR primary water

Abstract

The stress corrosion cracking mechanism of Alloy 600 in pressurised water reactor (PWR) primary water has been investigated. U-bend specimens (extracted from tubular products) were tested in simulated PWR primary water containing H₂¹⁸O. After testing, crack tips was characterised by nanosecondary ion mass spectrometry (nanoSIMS) and unstressed areas were analysed by standard SIMS. The results allowed oxygen (¹⁶O, ¹⁸O) penetration into the material to be evaluated and the oxide present at crack tips to be characterised. Experimental data were compared with results obtained by calculations performed according to Fickian diffusion laws and Whipple Le Claire theory.