2D simulation of the initiation and propagation of crack array under thermal fatigue

Various components of nuclear reactors are submitted to various thermo-mechanical loadings. Thermal fatigue cracking has been clearly detected in reactor heat removal system (RHRS) of pressurized water reactors (PWRs). The present study focuses on AISI 304 L stainless steel used in PWRs. The thermal fatigue behavior of this steel has been investigated using a specific thermal fatigue facility called “SPLASH”. This test equipment allows the reproduction of multiple crack networks similar to those detected during component inspections. The present study deals with the modeling of crack networks initiation and propagation. It is structured in two parts: (i) experimental details and main characteristics of the cracks networks, and (ii) numerical simulation of multiple cracks initiation and growth problem, using an elastic-plastic thermal-mechanical computation and a generalized Paris' law. The model presented in this study gives predictions in a good agreement with observations, as far as the evolution of the mean and deepest cracks during cycling is concerned.