Nuclear fusion

Welding technology supporting the development of next-generation energy systems has been reviewed as a special issue. In the present article, we take nuclear fusion as an example. ITER facility for the demonstration of scientific feasibility is being built in France under contract of international cooperation. First, the conceptual design of the fusion power plant is shown. Then, structure and materials of main components of ITER such as vacuum vessel, breeding blanket and divertor are discussed. Structural materials suffer strong irradiation of fast neutrons, so a lot of low-activation steels, tungsten and CFC are used, which are poor weldable. Furthermore the method of remote maintenance for activated materials has to be developed. We introduce recent results of R and Ds on welding technology, including laser welding, TIG welding, electron-beam welding and HIP joining. (author)