Analytical study of cover plate welding deformation of the radial plate of the ITER toroidal field coil

Omori, Junji; Koizumi, Norikiyo; Shimizu, Tatsuya; Okuno, Kiyoshi; Hasegawa, Mitsuru*

In the winding pack (WP) of the ITER TF coil, cover plates (CPs) are welded to radial plate (RP) after placing the conductors into the RP groove to fix it. The dimensions of the RP are 15 m high and 9 m wide, while its required tolerances are very severe such as flatness of 2 mm and in-plane deformation of about 2.5 mm. It is therefore necessary to reduce the deformation of the RP by CP welding. In order to estimate the weld deformation, a 1 m RP mock-up was fabricated and weld deformations were measured. From the test results, inherent strains have been obtained and the weld deformations of the full scale RP have been estimated. The RP deformations could be within the tolerances by the CP welding thickness of 2.5 mm in inboard region and 1.0 mm in outboard region. In addition, an alternative design, which improve the fabricability of the WP, was proposed. The analyses for the alternative design is performed and the results show the deformations could be reduced more.