Fabrication of double-walled section models of the ITER vacuum vessel

Trial fabrication of double-walled section models has been performed at Japan Atomic Energy Research Institute (JAERI) for the construction of ITER vacuum vessel. By employing TIG (Tungsten-arc Inert Gas) welding and EB (Electron Beam) welding, for each model, two full-scaled section models of 7.5/spl deg/ toroidal sector in the curved section at the bottom of vacuum vessel have been successfully fabricated with the final dimensional error of within /spl plusmn/5 mm to the nominal values. The sufficient technical database on the candidate fabrication procedures, welding distortion and dimensional stability of full-scaled models have been obtained through the fabrications.