Design and manufacturing of JT-60SA vacuum vessel

Masaki, Kei; Shibama, Yusuke; Sakurai, Shinji; Katayama, Masahiro*; Sakasai, Akira

JT-60SA vacuum vessel (VV) has the outer diameter of 10 m and the height of 6.6 m. The VV is supported by 9 legs. The material is 316L with low cobalt content of 0.05wt%. The VV has a double wall structure composed of inner/outer shells and ribs to ensure high rigidity at operational load and high toroidal one-turn resistance of 16 simultaneously. The double wall thicknesses are 194 mm at inboard and 242 mm at outboard. Inner/outer shells have 18-mm thicknesses. In the double wall, boric-acid water of 50C circulates at plasma operation to reduce nuclear heating of the superconducting coils. At the baking of 200C, nitrogen gas circulates in the double wall. Fundamental welding R&D and a trial manufacturing of the 20 upper half of the VV have been performed to study the manufacturing procedure. After the confirmation of the quality of the mock-up, manufacturing of the actual VV started in December 2009.