Design and manufacturing of vacuum vessel for JT-60SA

Vacuum vessel of JT-60 Super Advanced (JT-60SA) is composed of 18 port sections with 73 ports. The vacuum vessel has a D-shaped poloidal cross-section with a double wall structure, which is filled by shielding water for neutron. The vessel is made of AISI316L with low Cobalt content of <0.05 wt.%. In order to reduce manufacturing cost, fabrication procedure was reviewed and the shell thickness and arrangement of poloidal ribs are modified from original design. Reduction of the shell thickness and poloidal ribs has large impact on manufacturing cost. Integrity of basic structure was confirmed by FEM analyses for eddy and halo current electromagnetic load. Stresses at general part of VV body are enough smaller than the design limit. Maximum stress is found near the basement of baffle plate support legs and close to design limit.