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

Onozuka, Masanori*; Alfile, J. P.*; Aubert, P.*; Dagenais, J.-F.*; Grebennikov, D.*; Ioki, Kimihiro*; Jones, L.*; Koizumi, Koichi; Krylov, V.*; Maslakowski, J.*; et al.

Fusion Engineering and Design, 55(4), p.397 - 410, 2001/09

https://doi.org/10.1016/S0920-3796(01)00185-5

Development of welding, cutting and non-destructive testing (NDT) techniques, and development of remotized systems, have been conducted for on-site manufacturing and maintenance of the thick wall structure of the ITER vacuum vessel (VV). Conventional techniques, including TIG (tungsten inert gas) welding, plasma cutting and ultrasonic inspection, have been improved and optimized for the application to thick austenitic stainless steel plates. In addition, advanced methods have been investigated including reduced-pressure electron-beam and multi-pass NdYAG (neodymium-doped yttrium aluminum garnet) laser welding, NdYAG laser cutting, and EMAT (electro-magnetic acoustic transducer) inspection to improve cost and technical performance. Two types of remotized systems with different payloads have been investigated and one of them has been fabricated and demonstrated in field joint welding, cutting, and NDT tests on test mockups and full-scale ITER VV sector models. The progress and results of this development to date provide a high level of confidence that the manufacturing and maintenance of the ITER VV is feasible.