Fabrication of full-scale sector model for ITER vacuum vessel

Fabrication of full-scale sector model of ITER vacuum vessel, which was initiated in 1995 as a one of the Large Seven ITER R&D Projects, has been completed in September 1997. The full-scale sector model corresponds to an 18° toroidal sector made of SS 316L+N, is composed of two 9° sectors, Sector-A and B, which are spliced at the port center according to the current ITER design. In order to satisfy tight manufacturing tolerances of ±20 mm and to assure the structural integrity of double-walled structure, a combination of TIG (Tungsten Inert Gas Arc)/EB (Electron Beam) welding and TIG/MIG (Metal Inert Gas Arc) welding were adopted for Sector-A and B, respectively. Although the different poloidal segmentation and welding process were employed for the fabrication, the dimensional accuracy of within ±6 mm to the nominal values has been successfully demonstrated in the fabrication of both sectors. After the pressure and vacuum leak test, both sectors were shipped to the test site in Japan Atomic Energy Research Institute (JAERI) for the first demonstration test of automatic welding of the field joints between sectors. This paper describes the design, fabrication procedures, results obtained by the fabrication and the latest status of the full scale sector model