#112 French Regulator Halts Assembly of ITER Reactor
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Note: See April 28, 2022, article “More Defective ITER Reactor Sectors” for update and correction.
By Steven B. Krivit
Feb. 21, 2022
The assembly of the reactor core of the International Thermonuclear Experimental Reactor (ITER) is on hold, according to the French nuclear safety authority Autorité de Sûreté Nucléaire (ASN).
The reactor core will be assembled from nine massive vacuum vessel sectors, each one 440 tons of steel. Two sectors are on site, waiting to be lowered into the reactor chamber.
On Jan. 25, 2022, Bernard Doroszczuk, the chairman of the board of directors of ASN, sent a letter to Bernard Bigot, the director-general of the ITER organization. Doroszczuk told Bigot that Bigot is not authorized to lower the two sectors into the reactor chamber unless the ITER organization can guarantee that the installed sectors can later be separated and removed.
“Consequently, the assembly of the tokamak cannot be authorized,” Doroszczuk wrote.
At New Energy Times’ request, Evangelia Petit, the press officer for ASN, provided a copy of the letter today.
“The welding of these sectors [inside the tokamak pit] would represent an irreversible operation, which needs ASN’s formal approval in order to take place,” Petit wrote.
According to the timeline published on the ITER organization’s Web site, the first sector subassembly was scheduled to be lowered into the tokamak chamber, also called the tokamak pit, in December 2021.
Vacuum vessel sector supported by a frame in the assembly hall.
Damaged Vacuum Vessel Sectors
As New Energy Times reported on Nov. 10, 2021, both of the vacuum vessel sectors that have been delivered to the ITER site were damaged during manufacture. Either the sectors or parts of the sectors (details are unclear) fell at the manufacturing sites and sustained dimensional distortion, according to ASN.
As a result of the distortions, the subassembly of these sectors cannot be performed as planned in the spacious assembly hall. Instead, the ITER organization has proposed performing the subassembly of the damaged sectors inside the confined space, where the final assembly of the reactor core will take place.
If the sectors cannot be welded together properly, the reactor could cause excessive radiation during operation. Gamma-ray radiation and neutrons that will be produced during ITER’s operation will require proper conjoining of the nine sectors as well as the presence of a 13-foot-thick concrete wall surrounding the reactor chamber to protect reactor workers.
Last week, Petit explained to New Energy Times that ASN was unwilling to compromise its safety standards:
The specifications provided are not sufficient to demonstrate and guarantee compliance with the requirements, specifically concerning a) radiological protection material and [its] impact on the total weight of the tokamak and b) welding and related controls of the vacuum vessel sectors, given the existence of dimensional non-conformance. In order to go forward, we have requested IO to provide us with a consolidated design, carefully reviewed in order to check [compliance with] all safety and radiological protection criteria.
ASN learned about the damaged sectors during a July 2, 2021, inspection and reported its findings to Bigot on July 20, 2021. Since that time, according to public documents on the ASN Web site, the ITER organization has made repeated requests to ASN to allow the organization to proceed with installation of the damaged sectors using an alternate method.
Impasse
On Jan. 5, 2022, a meeting took place between the ITER organization, ASN, and another French nuclear regulator, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), in an attempt to resolve the impasse, according to Michel Claessens, former spokesman for the ITER organization, who maintains contacts with sources inside the organization.
“During a special meeting of the steering committee with ASN, IRSN, and the ITER organization on Jan. 5, 2022, ASN announced that the reactor assembly is not authorized, which means, in practice, a shutdown of the project,” Claessens wrote.
New Major Design Review Required
ASN told the ITER organization that the regulator is not satisfied with other aspects of the current reactor design because they present excessive risks of ionizing radiation to workers. These are excerpts, translated from French, from Doroszczuk’s letter to Bigot:
As is evident from the in-depth examination of your file and the many technical exchanges held between your teams and the ASN departments as well as the IRSN experts, the following elements apply:
– The “neutron budget” values that you anticipate during the operation of the installation are greater than the maximum neutron fluence to be taken into account for the dimensioning of installation.
– The elements received concerning the radiological maps do not make it possible to demonstrate that the limitation of exposure to ionizing radiation is controlled, a major challenge for an installation of nuclear fusion.
In particular, the progressive activation of materials under the effect of intense neutron flux is not properly taken into account, and the exposure of workers in adjoining premises to nuclear buildings should be assessed with realistic conservative assumptions. …
Given the elements noted above, ASN considers that this condition is not satisfied at this stage. Thus, the hold point related to the tokamak assembly cannot be lifted before February 1, 2022. Consequently, the assembly of the tokamak is suspended. In the immediate future, I urge you not to take any action that is difficult to reverse concerning the sectors of the vacuum chamber affected by dimensional non-conformities, so as not to impede your capacity to carry out the repairs that would be deemed useful with a view to their welding.
I invite you to make sure that you have a stabilized design of all the equipment associated with the vacuum chamber, the overall consistency of your sizing, with regard to all the requirements that you had set yourselves regarding the protection of workers, the public, and the environment, and the proper accounting of deviations and defects already noted during construction. An in-depth design review needs to be carried out before you again seek authorization to start assembling the tokamak equipment inside the cryostat.
Feb. 28: 2022: ITER Organization Releases Statement
Feb. 24, 2022: We have received some questions about the details of the damage to the sectors. Here’s a repeat of what we said in this article:
As New Energy Times reported on Nov. 10, 2021, both of the vacuum vessel sectors that have been delivered to the ITER site were damaged during manufacture. Either the sectors or parts of the sectors (details are unclear) fell at the manufacturing sites and sustained dimensional distortion, according to ASN.
The ASN document INSSN-MRS-2021-0650.pdf contains the best available information we have about the damage. Here are the statements in French, also translated to English.
Les inspecteurs ont notamment examiné par sondage le traitement des écarts et des modifications ainsi que les suites des chutes d’éléments de secteurs de la chambre à vide lors de leur manutention sur des sites de fabrication en Corée du Sud et en Italie. La découverte de falsification de certificats de qualifications de soudeurs, à la suite d’une information d’alerte de l’ASN, a également fait l’objet de vérifications.
In particular, the inspectors examined on a test basis the treatment of deviations and modifications as well as that the consequences of the falls of elements of sectors of the vacuum chamber during their handling on manufacturing sites in South Korea and Italy. The discovery of forgery of certificates of welder qualifications, following an alert from ASN, was also the subject of checks.
Chute d’éléments de secteurs de la chambre à vide: Des éléments de secteurs de la chambre à vide ont chuté lors de manutention sur les sites de fabrication, en Corée du Sud en avril 2021 et en Italie en mai 2021.
Falling elements of sectors of the vacuum chamber: Elements of the sectors of the vacuum chamber fell during handling on the manufacturing sites, in South Korea in April 2021 and in Italy in May 2021.
If anyone can provide more specific details about the damage, please let us know!
April 28, 2022: Last paragraph corrected from “Sectors of the vacuum chamber” to “Elements of the sectors of the vacuum chamber.”
