Conceptual design study of nuclear shielding for the steady state tokamak device JT-60SU

Abstract The neutron shielding structure of a vacuum vessel consisting of low activation materials as Al or Ti alloy are studied for the super-upgrade of the JT-60 (JT-60SU) design. A 25–40 cm thick water tank-type vacuum vessel using Ti6Al4V and boron (1% of 10 B) doped water are shown to be the best choice. This design concept gave results consistent with the design requirements: the one-turn resistivity of the vacuum vessel is ∼ 50 μω , and the dose rate inside the vessel is ∼ 15 mrem/h a year after shutdown. The total nuclear heating of the whole TF-coil can be reduced to ∼ 11 kW for a DD fusion neutron rate of 1 × 10 18 /s.