All-position reduced pressure electron beam welding for large fusion containment vessels

This paper describes the results of a comprehensive and continuing experimental programme to determine the Reduced Pressure Electron Beam Welding (RPEBW) parameters and penetrations achievable in the required weld conditions pertinent to large fusion containment vessels in general, and the ITER-FEAT vacuum vessel in particular, and leading towards the final goal of full procedure qualification. Key issues, including that of long working distance, are discussed.