ITER shield blanket and vacuum vessel

The Vacuum Vessel is part of the Tokamak-Basic Machine and provides the primary high vacuum and tritium boundary for the plasma. The vessel is also a major safety barrier and must support electromagnetic loads during plasma disruptions and vertical displacement events (VDE) and withstand plausible accidents without losing confinement. It is made from SS 316 LN and has a water cooled, double wall structure. The minor and major radii of the tokamak are 4.1 m and 13 m respectively, and the overall height is 14.5 m. The total thickness of this structure is typically in the range of 0.45-0.83 m. The inner and outer shells are made of welded plates, 40 mm in thickness. The space between the vessel shells is filled with an array of shield plate inserts which, in combination with the blanket and divertor, provide neutron radiation shielding for the coils. As the principal plasma facing component of ITER, the blanket system must be designed to perform power removal and shielding functions. The First Wall (FW) is the most critical component of the blanket and must be designed to remove the surface heat flux from the plasma, while, in combination with a structurally integral shield, reduce the nuclear effects in the vacuum vessel and protect the superconducting coils from excessive nuclear heating and radiation damage. The first wall is exposed to the 1500 MW fusion power at an average neutron wall loading of about 1 MW/m/sup 2/ and must be designed for a life of 0.3 MWa/m/sup 2/ during the Basic Performance Phase. In addition the First Wall must successfully withstand peaked thermal and electromagnetic loads resulting from plasma disruptions. The total electrical resistance of the vacuum vessel and the blanket structure is approximately 4.5 /spl mu//spl Omega/ to limit the induced eddy current flow while allowing magnetic field penetration.