France halts assembly of ITER nuclear reactor
The assembly of the core of the ITER International Experimental Thermonuclear Reactor, which is being built near the Cadarache Research Center on the French Côte d’Azur, has been suspended by a decision of the French Nuclear Safety Authority (ASN).
It was planned that the reactor core would be assembled from nine huge segments, each of which would weigh 440 tons. Two sectors are already in place, waiting to land in the reactor room, and according to the work schedule published on the ITER website, the first sector node was to be lowered into the tokamak room as early as December 2021, however, eventually in January 2022, the Chairman sent ASN Bernard Doroshchuk letter to ITER General Manager Bernard Pigott warning that these segments can only be installed in the reactor chamber if there is a guarantee that they can be removed later.
The fact is that even during manufacture, these sectors themselves or their parts were damaged during a fall and may be seriously deformed. Welding these segments inside a tokamak pit will be an irreversible process that requires official approval from the ASN, but in the absence of the above guarantees, tokamak assembly cannot be authorized.
Experts believe that due to deformations in the structure, it is impossible to assemble the segments in a planned manner in a spacious assembly hall. Instead, ITER suggested that this work be carried out inside an enclosed space where the final assembly of the reactor core will take place.
If the segments cannot be welded together properly, there is a risk of excessive radiation being released during the operation of the reactor. Protecting personnel from gamma rays and neutrons generated during the operation of ITER required a proper connection of the nine segments, as well as a four-meter-thick concrete wall surrounding the reactor chamber.
Before re-applying for permission to assemble tokamak equipment inside a cryostat, a new comprehensive analysis must be carried out.
