why does the design of EPR reactors continue to be debated?

The French nuclear industry is under pressure to avoid the Flamanville syndrome, the first French EPR reactor still not in service despite a 12-year delay on the site. A week after the presidential nuclear council, the Minister for Energy Transition, Agnès Pannier-Runacher, is going to the forge of the Framatome plant in Le Creusot (Saône-et-Loire) on Friday February 10. This is where the largest parts that will equip future EPR 2 reactors are manufactured. The State wants to speed up the production rate, but the validity of the design of these reactors is under debate.

“Totally Abnormal Vibrations”

The doubts begin in July 2021. The number one reactor at the Taishan power plant in China, built with the help of EDF, is then shut down. This plant is the first in the world to use EPR reactors. Crirad, an independent French laboratory known for its expertise, managed to obtain information, says its director, Bruno Chareyron: “The Crirad, thanks to the information transmitted to it by someone who works in the nuclear industry, was able to establish what happened, that is to say completely abnormal vibrations, which induces a degradation of the fuel assemblies linked to a design defect, inside the vessel, completely unprecedented.”

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The second alarm signal occurred last summer. IRSN, the organization that carries out technical studies for the Nuclear Safety Authority, recognizes in an opinion a design anomaly on the bottom of the EPR vessel. A defect identified during the studies but not taken into account.

There is a solution, however, believes Ludovic Dupin, of the French nuclear energy company: “It is not so much a design error of the tank. There is no need to rethink the design of the EPR. It is just a matter of doing a heat treatment. ‘we heat the materials and as a result, they are solidified and therefore they better hold the fuel in place once they have been heated.

Crirad asks the Nuclear Safety Authority to review its copy and refuse the commissioning of the Flamanville EPR scheduled for mid-2024 after a further delay.