Design study of top lid with clamp structure in JT-60SA cryostat

Nakamura, Shigetoshi; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira

The JT-60SA project is to contribute to realization of fusion energy by supporting exploitation of ITER and by complementing ITER and engineering issues for DEMO reactors. A main component providing vacuum insulation, radiation shield, and tokamak machine components' support, is cryostat. We present integrity of top lid of the cryostat, which is final part to close a cryostat vessel. We calculate clamp structural parameters, which are weight, dimension, and stiffness, required to fasten a top flange of the top lid with a body flange of the cryostat vessel. To achieve vacuum insulation of 10 Pa, the top flange and the body flange are lightly welded. Under vacuum condition, tensile load is loaded to the weld by bending deformation of the top flange. Bending moment is loaded to the weld by radial component of the deformation. The weld needs clamp structure to reduce these loads. We present integrity of the top lid with clamp.