The Cryoplant Buildings stand ready to cool ITER

ITER, the international fusion experiment, is unparalleled in many aspects. Besides the largest and most powerful Tokamak ever, some of its auxiliary plant systems are also feats of engineering. One of them is the cryoplant, the facility that will provide the refrigeration for the superconducting magnets, cryostat and vacuum pumps to operate. It will be one of the biggest in the world, with an installed cooling power of 1300 kW at 80 K (-193 °C) for nitrogen and 75 kW at 4.5 K (-269 °C) for helium. To generate, store, and distribute the cryogenic fluids, the ITER cryoplant features a range of components, such as compressors, cold boxes or the gigantic tanks procured by Europe.

As the commissioning of these systems advances, F4E has officially finished the cryoplant buildings. It is yet another success for Europe's construction teams and their industrial partners. The heavy works were carried by the Vinci, Ferrovial, Razel-Bec (VFR) consortium from 2015 to 2017. In late 2024, the last tasks on the building services by Demathieu Bard brought the project to a close. F4E and ITER Organization signed the symbolic hand-over certificate.

The four-metre-high concrete pads inside the compressor hall in 2017, before the installation of the heavy equipment. ©ITER Organization

The facility is 120 m long, with a footprint equivalent to a football field (5,400 m²). It houses most of the cryoplant's infrastructure, while the tanks and various cold boxes are located outside. Inside the biggest hall, a labyrinth of pipes and rows of helium compressors dominate the view. These 25-tonne components, which will pressurize the gases, are mounted on especially solid foundations. "For each compressor, we built a reinforced concrete pad, decoupled from the floor. Our engineers carried out precise calculations to make sure that the vibrations from the machines do not affect other systems", explains Romaric Darbour, F4E's Programme Manager for Buildings and Site Management. In total, the VFR teams poured 7.800 m³ of concrete to erect the cryoplant. Its façades were covered later with ITER's distinctive isolating grey cladding.

When at work, the 18 megawatt-class compressors will dissipate a lot of heat. The F4E and ITER engineers came up with an energy-saving solution: twelve heat exchangers will recover this heat and channel it into ITER's hot water loop, which feeds the heating system of the buildings.

View of the inside of the compressor hall, one of the two adjacent buildings that form the cryoplant facility, together with the external storage area. September 2019. ©ITER Organization

Adjacent to the compressors hall lies the area of the helium cold boxes. From these units, the cooled helium will flow through cryolines towards its clients in the Tokamak building via the 130-meter-long cryobridge. This ultra-modern aqueduct, crossing between buildings at 13 meters of height, was built by F4E's contractor Demathieu Bard. "The engineering of the ITER cryobridge was uniquely challenging, needing robustness as well as flexibility, within an intricate 90-degree layout. We are proud to have erected such a complex infrastructure within a tight timeframe, meeting the requirements thanks to the teamwork with F4E and ITER organization," expresses Sébastien Berne, Nuclear Activities Director of Demathieu Bard. Inside the bridge, technicians are progressing with the delicate installation of the cryolines.

The company was also in charge of the cryoplant's building services, under a separate contract. After installing all the electrical and ventilation systems, they recently completed the commissioning of the building's automated monitoring system, marking the end of the project. The facility is now ready to cool down the equipment for ITER to operate.

Take a tour through the cryoplant with the new video by ITER Organization.

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