Fatigue crack initiation and growth model in simulated PWR primary coolant environment

Abstract

Purpose of this study is to model statistical characteristics of crack initiation and crack growth in PWR environment and to investigate them. 2-step experiment was conducted, which was composed of periodical strain-controlled fatigue test for 3 kinds of strain range conditions in simulated PWR primary coolant environment with type 316 stainless steel and observation of cracks on specimen surface with 2-step replica method. Statistical dispersion of crack initiation and crack growth were modeled. It was confirmed that environmental effect on fatigue life was caused by reduction of crack initiation life and acceleration of “appeared” crack growth rate by coalescence of cracks and not affected by acceleration of crack growth rate.