Analysis of Residual Stresses and Assessment of Postulated Cracks in a Core Shroud Weld
In order to assess postulated cracks in weldments of a BWR core shroud residual stresses are calculated by simulating the welding process. In the numerical analysis, weld metal deposition and the sequence of weld passes follow the manufacture protocol. The calculations are performed using the finite element program ABAQUS and a material model with kinematic nonlinear hardening. Calculations of the crack driving parameter, the stress intensity factor, are carried out for postulated circumferential cracks using a numerical procedure, as well as by applying a weight function solution specially developed for cracks in a thin-walled cylinder. The results give rise to a discussion on the validity of linear elastic fracture mechanics for assessing defects in weldments. Additionally, for a complete circumferential crack the trend in the stress intensity factor is studied when the crack depth approaches the full wall thickness.