Overview of Welding Research Under the New Nuclear Manufacturing (NNUMAN) Programme

The New Nuclear Manufacturing (NNUMAN) programme was established in the UK in late 2012, to develop new manufacturing technologies for nuclear components. One of the themes of this programme is research to develop candidate advanced joining methods using arc and high-energy welding processes, for components manufactured using nuclear grade reactor pressure vessel steel SA508 Grade 3 Class 1. The key outcomes of this study are the comparison of residual stresses and mechanical properties of welded mock-ups as a function of different welding processes, together with the development and validation of numerical models to predict residual stresses and mechanical properties. This paper gives an overview of the NNUMAN welding programme, coupled with design of experiments to date. The ultimate objective of this research is aimed at determining the effect of the selection of welding process, on the performance of nuclear components with operational lifetimes of 60 years or greater.