EC FP7 Structural Performance of MULTI-METAL: Ambitions, results, implications and discussion

摘要

The purpose of this paper is to present a part of the results achieved within the MULTIMETAL project, its conclusion and recommendations, and proposal for further investigation. Focus is on the structural integrity assessment of dissimilar metal weld (DMW). The EURATOM supported project started in February 2012 and ended in 2015. The project is coordinated by VTT with 10 partner organizations from Europe: AREVA (SAS & GmbH), CEA, JRC, EdF-Energy, BZF, EDF, TECNATOM, JSI, and Studsvik Nuclear AB. The aim of the project was to develop a standard for measuring the fracture resistance of multi-metallic specimen and development of harmonized procedures for dissimilar metal welds (DMWs) ductile integrity assessment. DMWs connect ferritic and austenitic stainless steels and are present in a number of primary piping systems in light water reactors. They contain a number of different material zones, i.e. ferritic zone, austenitic zone, weld material and heat affected zones which differ significantly in their material properties and fracture behaviour. The project ambitions, results and implications are generally presented and discussed. The main work was focused on testing the three mock-ups containing DMWs resembling real DMWs from NPPs in terms of geometry, material and weld procedure. The material test program involved tests with standard geometry specimens (CT, SENB, SENT) which were cut from the mock-ups. Numerical calculations were performed utilising State-of-the-Art on integrity methods for DMW. The project also includes both experimental and numerical benchmarking and preparation of best practice documents.