Advanced Finite Element Analysis (AFEA) Evaluation for Circumferential and Axial PWSCC Defects

Abstract

The Advanced Finite Element Analysis (AFEA) methodology has been developed by the US NRC and the nuclear industry to evaluate the natural crack growth of primary water stress corrosion cracking (PWSCC) in nickel-based alloy materials. The AFEA methodology allows the progression of a planar crack subjected to typical SCC-type growth laws by calculating stress intensity factors at every nodal point along the crack front, and incrementally advancing the crack front in a more natural manner. This paper describes the enhancements that have been made to the existing AFEA methodology. The most significant enhancement was the feature to evaluate axial crack growth where the crack was contained within the susceptible material. In this paper, this methodology was validated by performing an AFEA evaluation for the axial crack that was found in the V.C. Summer hot leg dissimilar metal weld. Other enhancements to the AFEA methodology include; upgrade to the PipeFracCAE© software developed by Engineering Mechanics Corporation of Columbus, feature to handle non-idealized circumferential through-wall cracks, mapping of weld residual stress for crack growth, and determination of limiting crack size using elastic-plastic J-integral analysis that included secondary stress (weld residual stress and thermal transient stress) effects.