Conceptual design of KSTAR vacuum vessel

The Korea Superconducting Tokamak Advanced Research (KSTAR) is a steady-state-capable superconducting tokamak. The vacuum vessel (VV) system consists of the toroidal vessel inner and outer shells, radial, horizontal and vertical ports, vessel supports, plasma facing components (PFCs) and their supports. The vessel is a double wall design with inner and outer shells separated by ribs and filled with shielding water. SS316 was chosen as the vessel structure material because of its domestic availability and cost effectiveness. Since the vacuum vessel must support many other major components of the machine, a comprehensive analysis was performed to verify the structural integrity of the vessel. A critical buckling pressure of 20 atm was obtained based on a fundamental stability analysis which included the overall vessel structure. Using preliminary transient disruption scenarios, a simple transient analysis was performed to investigate the vessel structural response under dynamic loading conditions. It was determined that the vacuum vessel itself is strong enough to endure the forces induced by eddy current during disruptions.