Cracks and dismantling: the construction of the ITER fusion reactor will take a long time

Eric Bottlaender

Space specialist

November 29, 2022 at 4:25 p.m.


ITER Tokamak Pit November 2022 © ITER Organization

The space devoted to the assembly of the reactor, with the first of the nine segments of the tokamak visible on the left, in the center © ITER Organization

Hard blow for the fusion reactor built in France. After more than 2 years of assembly, part of the ITER research tokamak will have to be dismantled after discovering cracks. The installation was already unlikely to see its “first plasma” in 2025…

There should also be additional costs, with a heavy bill at stake.

Crack on fusion

This is an announcement that was unfortunately expected following the detection in November 2021 of small cracks in the thermal coating of one of the 9 giant segments forming the walls of the tokamak, the central element of the prototype fusion reactor ITER . The investigation delivered its conclusions: particles of chlorine remained trapped on the silver coating and corroded it.

Combined with significant mechanical stress during the welding of the cooling elements (which will operate at -269°C or 4 degrees Kelvin), this corrosion is the cause of cracks 1.5 to 2 mm deep. This may seem negligible for complex machinery, each segment of which is 18 meters high and weighs 1,350 tons… But the damage is done, and it will be necessary not only to replace some of the parts of the future segments, but also to dismantle the one that is already in place in the reactor building. This delicate operation will take several months on its own.

Major delays ahead

The time to test, observe, dismantle and replace the cracked elements, then to ensure that the defect will not reoccur before resuming work, ITER should “lose” about 2 years on the current schedule, which planned a first plasma for 2025.

But this will be added to other delays that were not yet taken into account, in particular those due to the health crisis (the elements of ITER are produced all over the world over periods of several years) and those caused by the Russian invasion of Ukraine, which indirectly created tensions over the supply of materials and parts, while Russia is still part of the consortium. Experts thus evoke 5 years of delay and 1 billion euros of additional costs in an article on The echoes.

ITER Tokamak element 2022 © ITER Organization

One of the 9 elements on which the teams will have to redo the welds and work on the thermal insulation © ITER Organization

ITER being the first assembly of its kind on this scale and on this power range (even if it is a research project), the teams were not immune to a discovery of this kind. However, it also highlights the difficulty inherent in this gigantic project with very tight tolerances.

Fusion, which is attracting more and more players, both public and private, for its energy promises, will not be able to come to the rescue of the problems of electricity production for at least a decade. The understanding of the internal phenomena, of this extreme physics and of the associated reactions should however progress despite the delay of ITER. Indeed, several other research facilities around the world are related to the same theme, on more specific aspects of fusion.

Source : The echoes

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