In the heart of the biggest fusion device extremely cold and hot temperatures will coexist. On the one hand, the superhot plasma is expected to reach 150 million ˚C and on the other, the most advanced cryogenic technologies will generate freezing low temperatures for the ITER magnets, thermal shields and cryopumps. For instance, the magnets will be cooled with super critical helium to reach a superconducting state at 4.5 K, close to absolute zero, to confine the hot plasma.
Europe will provide the Liquid Nitrogen (LN2) Plant and auxiliary systems that will cool down, process, transfer and recover the cryogenic fluids of the machine. Two nitrogen refrigerators will be manufactured along with two 80 K helium loop boxes, warm and cold helium storage tanks, dryers, heaters and a helium recovery and purification system. Another ITER party contributing to the cryoplant is India, which among other items, has under its responsibility the delivery of interconnecting lines and cryodistribution equipment.
The six valves that will control the helium flow from the 80K loop boxes to the thermal shields and cryopumps of the machine, have been manufactured by Flowserve, India, a subcontractor of Air Liquide Global E&C Solutions France, holder of the contract to deliver the LN2 Plant and Auxiliary Systems. The valves are almost five times bigger than the average cryogenic valves found on a standard helium liquefier: they measure 2.5 metres high, 0.7 metres wide and weigh over 1.5 tons. The maximum flow through these valves is over 4.4 kg/second which is more than twice what is normally released through a helium valve in the biggest helium liquefiers.
In line with the motto “one project-one team”, ITER International Organization coordinated the valves inspection exercise delegating to India’s Domestic Agency the responsibility to validate the manufacturing of the equipment paid by Europe. The equipment has passed the acceptance criteria and is on its way to China where it will be assembled on the cold boxes.