Speaker
Kyohei Natsume
(Tokamak System Technology)
Description
JT-60SA is a tokamak device using superconducting coils to be built in Japan, as a joint international research and development project involving Japan and Europe. The JT-60SA helium refrigerator system (HRS) supplies supercritical or gaseous helium to cold components: superconducting coils, coil supporting structures, cryopumps, high temperature superconductor current leads (HTS CL), and thermal shields. The transfer line is a vacuum heat-insulation multiple piping and inserted to the tokamak hall from the cryogenic hall, where HRS is installed. Installation space around the tokamak is limited due to reuse of the building of JT-60U, heating instruments, diagnostics and maximization of plasma volume. Therefore, small 11 valve boxes are installed around the cryostat instead of a large distribution box. The valve box is cylindrical form: 2 m in height and 1.4 m in outer diameter. The transfer line connects directly the tokamak cryostat penetrating the wall of the tokamak hall. Cold helium in pipes from the transfer line distributes to cold components passing through in-cryostat piping, valve boxes, a cryopump valve unit, and coil terminal boxes, more than once. The HTS CL is placed in the coil terminal box and requires cold helium supply lines and a return line for 300 K. The 300 K line is returned to HRS apart from the transfer line. Some valve boxes have a safety valve unit. When a fast discharge occurs on superconducting coils, the safety valves are opened and the cold helium gas goes to a quench tank through a quench line. All lines mentioned above are required to satisfy criteria of the pressure drop and withstand the gravity load, the displacement due to vacuuming the cryostat and cooling down the cold components, and the seismic load. In this work, the design status and the manufacture progress of these cryodistribution lines are reported.
Co-authors
Haruyuki Murakami
(Tokamak System Technology, Japan Atomic Energy Agency, Naka Ibaraki, Japan)
Kaname Kizu
(Tokamak System Technology, Japan Atomic Energy Agency, Naka Ibaraki, Japan)
Katsuhiko Tsuchiya
(Tokamak System Technology, Japan Atomic Energy Agency, Naka Ibaraki, Japan)
Kyohei Natsume
(Tokamak System Technology, Japan Atomic Energy Agency, Naka Ibaraki, Japan)
Yoshihiko Koide
(Tokamak System Technology, Japan Atomic Energy Agency, Naka Ibaraki, Japan)
