Residual Stress Study in Dissimilar Metal Welds of a PWR Pressurizer Surge Nozzle: Validation of Developed Fast Analysis Method and Examination of Safe-End Length Effect

Abstract

It is necessary to establish properly reliable weld residual stress analysis methods for accurate crack initiation and growth assessment of primary water stress corrosion cracking, which may occur in nickel-based dissimilar metal welds in pressurized water reactors. The US Nuclear Regulatory Commission and the Electric Power Research Institute cooperatively conducted an international round robin for weld residual stress analysis to improve stress analysis methods and to examine the uncertainties involved in the calculated stress values. In this paper, the results from the authors’ participation in the round robin were reported. In the round robin, the weld residual stress in a nickel-based dissimilar metal weld of a pressurizer surge nozzle mock-up was computed under various analysis conditions. The residual stress analysis results computed by a welding simulation code currently being developed that uses the iterative substructure method were in good agreement with the measurements. Also, the effect of safe-end length on residual stress distribution was examined as an additional discussion point.