Development of stress intensity factor solution for surface crack at nozzle corner in reactor pressure vessel

The stress intensity factor (SIF) for a crack at nozzle corner is a key parameter in the structural integrity assessment of nozzle in a reactor pressure vessel (RPV). Although various SIF solutions for surface cracks at nozzle corners have been proposed, most focus only on the deepest point of the crack, and the information about geometric dimension of the nozzle corner is not clear. According to previous fatigue test results regarding the surface crack at the nozzle corner, the amounts of crack growth at the surface points were larger than that at the deepest point of the crack. Such results imply that SIFs at the surface points may be higher than that at the deepest point. It is necessary to provide SIF solutions for both surface and deepest points to increase the reliability of the structural integrity assessment. Through finite element analyses, this study developed SIF solutions for two surface points and the deepest point of a surface crack at the nozzle corners. The solutions correspond to the geometric dimensions of the nozzle corner and crack size.