nuclear fusion reactor assembly has been suspended

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ITER has suffered a very important setback. The assembly of the first two sectors of the vacuum chamber of the nuclear fusion reactor has been suspended by ASN, which is the French Nuclear Safety Authority. During the last few months this very important project, which is being carried out in the French town of Cadarache, seemed to be progressing as planned, but this setback has put it in the spotlight.

On January 25, Bernard Doroszczuk, who is the head of ASN, sent an official statement to Bernard Bigot, the general director of ITER, in which disavows it to install the first two sectors of the vacuum chamber of the reactor inside the pit in which it will be housed.

The reason that has led ASN to make this decision is that in the current circumstances this agency cannot guarantee safety of the people who will operate the reactor when the first plasma tests start, which are planned for 2025.

What has happened and why the assembly has been suspended

Last year the first two sections of the reactor’s vacuum chamber arrived at ITER’s facilities, a stainless steel and boron enclosure that when fully assembled will weigh no less than 8000 tons.

Inside, the fusion of deuterium and tritium nuclei takes place, so one of its most important functions is to act as first containment barrier of residual radiation that might not be retained by the mantle (blanket) that will cover the internal walls of this chamber.

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As we can guess, it is essential that the assembly of the sections that make up the vacuum chamber be absolutely accurate and guarantee the tightness of the enclosure not only to ensure the correct operation of the reactor, but also, and above all, to protect the people who will work in the facilities from gamma radiation and high-energy neutrons resulting from the fusion of the nuclei of deuterium and tritium.

As we have explained in other articles, one of the challenges posed by nuclear fusion is dealing with the neutron that is ejected with an energy of 14 MeV (megaelectronvolts), which is a lot of energy, when a deuterium nucleus and a tritium nucleus merge.

One of the challenges posed by nuclear fusion is dealing with the neutron that is ejected with an energy of 14 MeV

These extremely high-energy neutrons are very important because they are the ones that, in practice, will allow us to produce the electrical energy we need. But at the same time they represent a very aggressive form of radiation which can significantly degrade the materials used in the reactor.

The problem that ITER faces is that, according to ASN, under current conditions the two sectors of the vacuum chamber that were being prepared to be assembled and housed in the final location of the reactor cannot be installed because have undergone structural deformation.

Iter Ap

a document of the body responsible for French nuclear safety reflects that these two sections of the vacuum chamber suffered a fall during handling when they were being manufactured. One of the sectors has been produced in South Korea, and suffered the blow in April 2021; and the other has been manufactured in Italy, and suffered damage in May 2021.

Instead of repairing the damage to the sectors in the plants where they were manufactured, the technicians decided to send them to ITER with the intention that dimensional distortion that they suffered was evaluated and corrected in the same facilities where the reactor is being assembled.

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The structural deformation of both sections of the vacuum chamber prevents them from being assembled correctly

Once at ITER, they verified that the structural deformation of both sections of the vacuum chamber prevented them from being assembled correctly in the hangar where the reactor components are prepared before being housed in their final location, so they chose to assemble them directly. in the pit of the nuclear fusion reactor.

And, given the circumstances, in a not entirely unexpected turn of events, the highest authority on French nuclear safety has decided to intervene and prohibit assembly of these two sectors.

The reason is that, as I mentioned above, if they are assembled at the final location of the reactor it will not be possible to guarantee the required level of protection against gamma radiation and high energy neutrons. Plus, this operation is not reversiblewhich could irremediably compromise the viability of a project in which many nations have invested a great deal of time and money.

Iter2

And now that?

The solution to this gap proposed by ASN requires a thorough review of the design not only of the vacuum chamber of the nuclear fusion reactor, but also of other elements that, according to this body, do not meet the requirements that seek to protect the people who will operate from the harmful effects of ionizing radiation.

What is not yet clear is the impact that this setback will have on the itinerary set by EUROfusion for ITER

Given this situation, those responsible for ITER have no choice but to carry out this review and conscientiously repair the dimensional distortion suffered by the first two sectors of the vacuum chamber that were being prepared for assembly.

What is not yet clear is the impact that this setback will have on the itinerary set by EUROfusion for ITER. The assembly of the nuclear fusion reactor should be completed in 2025, and that same year they should start the first tests with plasma, but given the circumstances it is possible that these two important milestones will arrive later than expected. A real pity.

Images | ITER

Via | New Energy Times

ITER has suffered a very important setback. The assembly of the first two sectors of the vacuum chamber of the…

ITER has suffered a very important setback. The assembly of the first two sectors of the vacuum chamber of the…

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