Welding technology on sector assembly of the JT-60SA vacuum vessel

Abstract Manufacturing of JT-60SA Vacuum Vessel (VV) is under the onsite sector assembly, where ten VV sectors are to be welded together into a torus. The vessel is 6.6 m height and 5 m major radius and a double wall structure with the thickness of 18 mm and locally 30 mm, and total dimensional tolerance is designed to avoid any interference due to operational displacements. In this paper, two issues are focused: the onsite sector assembly concept and sector welding technology. The assembly concept is a contrivance to fulfil high precision as a large torus VV and efficient procedure, and obtained with combination of the direct butt joint and splice plate joint. The welding technology is a method to realize the VV, and investigated on acceptable error sizes with the test pieces for the onsite manipulator welding. Correction method of sector edge is also confirmed by the mock-up. Moreover, application to the onsite sector assembly is discussed. The onsite assembly has been started by this concept with its welding technology.