Magnet shielding effectiveness of the proposed blankets for ITER

During the conceptual design phase of the International Thermonuclear Experimental Reactor (ITER), several tritium breeding blanket designs were proposed by the four international parties, the US, the USSR, Japan (J), and the European Community (EC). The US, J, and EC designs utilize solid breeders with beryllium multipliers, while the USSR proposes an LiPb blanket design. All blankets are water cooled and use 316 SS as structural material. The shielding effectiveness of the different blanket designs was compared on the same basis and the radiation level at the superconducting toroidal-field magnets was assessed. The analysis shows that the inboard (i/b) blanket, in particular, has significant impact on magnet damage and total heating. For the US design, all magnet radiation limits are met with the current 84-cm-thick i/b region. For the other designs, the i/b blanket design should be modified to satisfy the magnet radiation limits, or 3-7 cm additional i/b shielding should be provided depending on the blanket type. The impact of the latest divertor design on the magnet damage was also analyzed, and the combined effect of both blanket and divertor designs on the overall magnet heat load was assessed