PWSCC growth analyses by boundary element method considering weld residual stress distributions

Primary water stress corrosion cracking (PWSCC) is an important issue for dissimilar metal welds in pressurized water reactors due to mainly high weld residual stress (WRS). With regard to the PWSCC evaluation, while systematic stationary crack analyses ranging from initial to final lengths have been extensively adopted, they are repetitive and may not realistic. In the present study, growing crack analyses by boundary element method as well as a WRS were carried out for a typical pressurizer surge nozzle, and compared with those of conventional stationary crack analyses by finite element method and ASME code equations. Subsequently, sensitivity analyses were performed in use of three crack growth criteria having different equivalent stress intensity factor (SIF) definitions and their results were quantified to recommend practical one. As anticipated, ASME code provided the highest value due to inherent conservatism of the influence function method. Discrepancies in the SIF values between the growing and stationary crack analyses increased as the cracks became deeper and longer because their shapes were significantly distorted due to complex WRS distributions.