In Cadarache, the Iter nuclear fusion project does not fear sanctions against Russia… for now

No crazy activity, Wednesday afternoon, April 6, at the Iter site in Cadarache (Bouches-du-Rhône), where it has been built since 2010 the international scientific demonstrator of nuclear fusion. But construction of the tokamak, in which the very meager gaseous mixture of deuterium and tritium (two isotopes of hydrogen) must be confined to create the same energy on Earth as the Sun, continues well. In the large assembly hall, which adjoins the pit where the tokamak is built piece by piece, the teams of the Chinese consortium, including Framatome (which won one of the two assembly contracts), are hard at work.

But without hectic pace. The assembly of the first of nine vacuum chamber modules took 36 months. “We are doing things here that have never been done. But we learn. The assembly of the second module will only take 17 months”, explains Robert Arnoux, communication manager at Iter, responsible for the visit. It involves inserting in and around a huge piece of steel weighing 440 tons, the vacuum chamber sector, 17 meter tall vertical coils weighing 350 tons and heat shield segments. Each of the nine modules, which will then have to be welded together to form segments, ultimately weighs around 1,300 tons. Precision work, where the tolerance is less than a millimeter! “It is watchmaking work on pieces worthy of a shipyard”summarizes the Iter spokesman.

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A calendar already under review


The third sector of the vacuum chamber, delivered by Korea, awaits its turn.

In the room, the third of the four sectors of vacuum chambers built by South Korea, is waiting to be moved vertically for the assembly of a new module. It won’t be for a few months. The descent of the first section, made up of the first two welded modules, to the tokamak well, initially planned for December 2021, is frozen. The French Nuclear Safety Authority expects engineers from Iter technical solutions to unresolved issues related to the radiological protection of workers and the load-bearing architecture of the building, as well as the irreversibility of the welding of the first two sections of the vacuum chamber, which are affected by dimensional nonconformities.


It will take 17 months to assemble the second module of the Iter tokamak vacuum chamber, compared to 36 months for the first.

Among the Covid-19 pandemic that slowed down the construction site in 2020, and these new technical challenges, the Iter calendar is being revised. But this questioning should not postpone the date of the first plasma planned since 2016, for December 2025, assures the person in charge of communication. This leaves time for the last reel of the Tokamak to arrive, which Russia must deliver. “It is still being tested in St. Petersburg. And we won’t need it for several years anyway.”says Robert Arnoux, in response to The impact of the war in Ukraine and sanctions against Russia over the project. Russia also delivers two to three busbars per year, large pieces of aluminum for very high voltage supply. “Deliveries are being made continuously, and Russia must deliver new ones, but we have reservations”certifies once again the spokesman.

A project impervious to diplomatic crises


In its shaft, the Iter tokamak is assembled piece by piece by a Chinese consortium.

This atypical international scientific project, launched in 2008, is led and financed up to 40% by Europe and 9% by each of the following countries: Russia, Chinathe JapanSouth Korea, theIndia and the United States. Originality of this extraordinary initiative of 20,000 million euros? The financing is 90% in kind, with parts built in each of the partner countries.

The Iter site (which adjoins a CEA site), where 4,000 people work, including 2,500 on site, is like the international zone of an airport: an offshore zone. “Here, it is not a project in collaboration with Russia. We are a seventh Russian away”explains Robert Arnoux, who remarks that Iter “it has experienced other diplomatic crises among its members, without the project being questioned”. A project “for the benefit of all mankind”which began in November 1985 in Geneva (Switzerland)… by the General Secretary of the Communist Party of the Soviet Union, Mikhail Gorbachev and the then President of the United States, Ronald Reagan.

Photo credit: Aurélie Barbaux

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