Recent Developments of Fracture Mechanics Tools for Nozzle Corners

Abstract

A recent effort was performed within AREVA-NP in order to develop and validate specific tools dedicated to the Fracture Mechanics Assessment of nozzle and penetration corners. This work is motivated by the need to perform accurate defect assessments for this geometry potentially submitted to a high level of stress. It includes: • The development of a specific compendium for the calculation of the Stress Intensity Factor under various types of loading like internal pressure or cold thermal shocks; • The evaluation of the effect of plasticity through simplified analytical schemes; • The validation through the comparison to existing solutions. One important target of those tools being the Fatigue Crack Growth evaluation under cyclic thermal shock loading situations, a validation of the fully analytical evaluation scheme was performed by a comparison to a complex 3D Finite Element Modelling of a defect propagating at a flange corner. This comparison is presented in the paper and illustrates the large benefit in terms of time and simplicity of the analytical scheme for such evaluation.