The Impact of Key Simulation Variables on Predicted Residual Stresses in Pressuriser Nozzle Dissimilar Metal Weld Mock-Ups: Part 2—Comparison of Simulation and Measurements

Abstract

British Energy (BE) has funded a large work programme to assess the possible impact of primary water stress corrosion cracking on dissimilar metal welds in the primary circuit of the Sizewell ‘B’ pressurised water reactor. This effort has included the design and manufacture of representative pressuriser safety/relief valve (SRV) nozzle welds both with and without a full structural weld overlay, multiple residual stress measurements on both mock-ups using the deep hole and incremental deep hole methods, and a number of finite element weld residual stress simulations of both the mock-ups and equivalent plant welds. Three organisations have performed simulations of the safety/relief valve nozzle configuration: Westinghouse, Engineering Mechanics Corporation of Columbus (EMC2) and the Australian Nuclear Science and Technology Organisation (ANSTO). The simulations employ different welding heat input idealisations, make different assumptions about manufacturing history, and use a variety of different material constitutive models, ranging from simple bilinear kinematic hardening to a full mixed isotropic-kinematic formulation. The availability of both high quality measurements from well characterised mock-ups, and a large matrix of simulations, offers the opportunity for a “mini-round-robin” examining both the accuracy and key solution variables of dissimilar metal weld finite element simulations. This paper is one of a series at this conference that examine various aspects of the BE work programme. It draws together residual stress measurement results and the results of all three simulation campaigns (described in detail in other papers at this conference) to examine the impact of manufacturing history, thermal modelling assumptions, material constitutive models and other key solution variables on the accuracy of residual stress predictions in this dissimilar metal weld geometry.