Progress on manufacturing of HV bushing for ITER NBTF

Tobari, Hiroyuki; Dairaku, Masayuki; Kojima, Atsushi; Umeda, Naotaka; Abe, Hiroyuki; Seki, Norikatsu; Shibata, Naoki; Kashiwagi, Mieko; Watanabe, Kazuhiro; Hanada, Masaya

JAEA procures the HV bushing for NBTF, which is under construction in Padova, Italy. To insulate rated voltage of 1 MV, large-area, five-layered electrostatic screens are installed in the limited space inside the HV bushing. However voltage holding characteristics of such large-area, multi-layer electrode is not clarified, and this characteristics is investigated with mockup electrode scalable to the HV bushing. Then, the HV bushing has been designed with voltage holding characteristics derived from the mockup experiment. Assembly of the HV bushing has been finished by September, 2015. Now, voltage holding test of the manufactured HV bushing is on-going, and voltage holding capability up to 240 kV for each of electrostatic screen layer. After confirmation for 1 MV insulation, the HV bushing will be shipped to NBTF site.