Japan has completed manufacturing eight huge toroidal-field magnetic coils (TF coils) for the International Thermonuclear Experimental Reactor (ITER), its share of that portion of the project. Japan’s National Institute for Quantum and Radiological Science and Technology (QST) made the announcement on February 21. QST had manufactured four of the coils by 2021, jointly with Mitsubishi Heavy Industries (MHI), and produced the remaining four with the Toshiba Energy Systems & Solutions (Toshiba ESS), completing Japan’s commitment.
TF coils are major ITER components. They are D-shaped superconducting-coils about 16.5 meters high (equivalent to a five-story building), about nine meters wide, and weigh about 300 tons. A total of 18 coils will be arrayed in a radial pattern around the vacuum vessel and generate a magnetic field of up to 12 teslas in order to confine ITER’s dense, high-temperature plasma. A total of 19 TF coils are being manufactured, nine of them (including one spare) by Japan and ten by the EU. Despite their huge size, accuracy greater than 1/10,000 is required (on the order of 1 or 2 millimeters).
Upon completion of TF coil production, QST and Toshiba ESS said that they had “demonstrated steady progress in manufacturing components for the ITER project, and shown the significance of Japan’s contribution.”
The first units of TF coils for which Japan was responsible were made by QST and MHI. At a ceremony marking their completion held at MHI’s Futami Plant in Hyogo Prefecture in January 2020, then ITER Director-General Bernard Bigot, who passed away in 2022, praised Japan’s technological capabilities, saying, “Japan always makes contributions at the core of the project, and is a driving force for nuclear fusion development in the world.”
ITER is under construction at Saint Paul lez Durance, France, with a target of beginning fusion operations in 2035. Of the Japan-made TF coils, seven have already been transported to the site. At a meeting of the ITER Board of Directors held in November 2022, the progress rate of construction to commencement of operation was put at 77.5% (as September 30, 2022).