Thermal fatigue crack networks: an computational study

Various components of nuclear reactors experience various thermo-mechanical loading. Thermal fatigue cracking has been clearly detected in reactor heat removal system (RHRS) of Pressurized Water Reactors (PWRs). The study presented here is focused on the AISI 304L stainless steel used in PWRs. The thermal fatigue behavior of this steel has been investigated using a specific thermal fatigue facility called “SPLASH test”. This test equipment allows the reproduction of multiple cracking networks similar to those detected during inspections. The present study deals with the modeling of cracking network development. It is structured in two parts: (i) experimental results and main characteristics of the crack networks, and (ii) numerical simulation on the multiple crack growth problem, using a modified stress intensity factor, and a generalized Paris' law. In spite of simplified assumptions, the model predictions are in good agreement with observations, as far as the evolution of the mean and deepest cracks during cycling are concerned.