Design of the ITER vacuum vessel

The vacuum vessel is categorized as a component of Safety Class 1 and is required to have a reliable structure and be manufactured by conventional methods. The vacuum vessel must support electromagnetic loads during plasma disruptions and vertical displacement events (VDE) and withstand plausible accidents without losing confinement. The total electrical resistance of the vacuum vessel and the blanket structure should be approximately 8-10 μΩ. The vacuum vessel has a double wall structure to provide structural and electric continuity in the toroidal direction. The inner and outer shells and poloidal stiffening ribs between them are joined by welding, which gives the vessel the required mechanical strength. The space between the shells will be filled with steel balls and plate inserts. Steel balls are viewed as the preferred option, with plates used in locations where steel balls will not reliably fill the space. Total thickness of the vacuum vessel is 0.4-0.7 m, and the overall height of the toroidal shell is approximately 15 m. Total heat deposition in the vacuum vessel is 0.2-2.5% of the fusion power, with the specific value depending on the shielding performance of the blanket. The maximum nuclear heating rate is calculated to be 0.04 MW/m3 in the vacuum vessel. The vacuum vessel coolant is envisaged to be water, which has higher shielding performance and no MHD problems