Kyoto Fusioneering lands JT-60SA contract for cryogenic thermal shields in world’s largest tokamak

Kyoto Fusioneering has secured a contract from the National Centralized Tokamak Upgrade program to deliver key components for the JT-60SA tokamak, one of the world’s largest fusion research facilities. The company will manufacture and supply 24 cassette vacuum vessel thermal shields along with their support structures to manage heat loads in the extreme vacuum environment.

The shields use Inconel 625 material to withstand temperatures from cryogenic levels up to 300 degrees C while maintaining structural integrity under intense plasma heat fluxes. Engineers at Kyoto Fusioneering designed the shields with integrated cooling channels that circulate supercritical helium at 80 K to absorb and dissipate thermal radiation from the plasma-facing walls.

Each shield weighs around 2.5 tonnes and measures roughly 7 meters long by 5 meters wide, forming a toroidal enclosure that protects the vacuum vessel from radiative heating during high-power discharges exceeding 40 MW. Precision machining ensures tolerances below 0.5 mm to achieve uniform cooling and avoid hotspots that could compromise the tokamak’s superconducting magnets.

The JT-60SA project aims to validate plasma control techniques for ITER and future DEMO reactors, with the thermal shields playing a role in enabling stable long-pulse operations up to 1000 seconds. Kyoto Fusioneering’s delivery builds on its expertise in fusion blanket modules and high-temperature components. Production starts next year at the company’s Kyoto facility, with installation targeted for 2028.