An Investigation of the Stress Intensity Factor Along a Corner Crack in Pressurizer Vent Nozzle Penetration Weld

Abstract

Elastic–plastic fracture mechanics as well as linear-elastic fracture mechanics may be applied to evaluate a flaw in ferritic low alloy steel components for operating conditions when the material fracture resistance is controlled by upper shelf toughness behavior. In this paper, the distribution of the stress intensity factor (SIF) along a corner crack using elastic–plastic fracture mechanics technique is investigated to assess the effect of a structural factor on mechanical loads in pressurizer vent nozzle penetration weld. For this purpose, the stress intensity factor and the plastic-zone correction of a corner crack are calculated under internal pressure, thermal stress, and residual stress in accordance with Electric Power Research Institute (EPRI) equation and Irwin’s approach, respectively. The resulting stress intensity factor and the plastic-zone correction were compared with those obtained from Structural Integrity Associates (SIA) and Kinectrics Inc., and were observed to be in good agreement with Kinectrics results.