Manufacturing and maintenance technologies developed for a thick-wall structure of the ITER vacuum vessel

Development of welding, cutting and non-destructive testing (NDT) technique s, and development of remotized systems have been carried out for on-site m anufacturing and maintenance of the thick-wall structure of the Internation al Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV). Convention al techniques, including tungsten inert gas welding, plasma cutting, and ul trasonic inspection, have been improved and optimized for the application t o thick austenitic stainless steel plates. In addition, advanced methods ha ve been investigated, including reduced-pressure electron-beam and multi-pa ss neodymium-doped yttrium. aluminum garnet (NdYAG) laser welding, NdYAG la ser cutting, and electro-magnetic acoustic transducer inspection, to improv e cost and technical performance. Two types of remotized systems with diffe rent payloads have been investigated and one of them has been fabricated an d demonstrated in field joint welding, cutting, and NDT tests on test mocku ps and full-scale ITER VV sector models, The progress and results of this d evelopment to date provide a high level of confidence that the manufacturin g and maintenance of the ITER VV is feasible. (C) 2001 Elsevier Science B.V . All rights reserved.