Overview of the JT-60 Super Upgrade Design

A conceptual design of a steady-state tokamak, JT-60 Super Upgrade, is being carried out. The present JT-60 facility will be fully utilized for this upgrade. The major objective of JT-60SU is to establish an integrated basis of physics for steady-state tokamak reactors such as SSTR. JT-60SU aims at investigation of steady-state operation relevant to the reactor regime. The technology development for long pulse operation and research for fusion safety improvement are also aimed at. The toroidal field coils are designed with using an advanced disk structure to improve the force transmission to the structure material. A modified three-in-hand grading using a circular Nb 3 Al and NbTi cable-in-conduit conductors is also adopted. A 40 cm thick water tank-type vacuum vessel made of Ti-6Al-4V, and boron (1% of 10 B) doped water is chosen for the vacuum vessel to reduce activation and to increase neutron shielding. Through these studies, we plan to conduct advanced tokamak experiments in JT-60SU for steady-state tokamak reactors. These studies will also contribute to the steady-state bum in ITER as an ultimate goal.