Advanced welding processes for fusion reactor fabrication

The huge scale and complexity of proposed fusion reactor structures has placed new demands upon fabrication technology and material performance. The need to weld substantial material thicknesses with severe service performance requirements, often in a multi-positional mode, over extended distances, certainly presents a formidable series of challenges. Of course, conventional welding processes can offer some solutions but welding times will be very long and component distortion potentially large. Fortunately, these challenges can be addressed, at least in part, by recent advances in electron beam and laser beam welding technology. Also recent developments in friction welding processes could offer benefits for the manufacture of some components. Specifically in the case of electron beam welding, TWI has developed a means of producing deep, narrow welds in a relatively poor vacuum. This new process variant called reduced pressure electron beam (RPEB) welding is being studied for fusion reactor vessel fabrication. Process advantages will be described. The work undertaken by TWI on behalf of the UKAEA for the EU Task No. T301/1 programme will be covered by a poster presentation at this conference. Recent advances in high power Nd:YAG laser welding and Friction Stir welding developments, which have taken, place at TWI will also be described.