Cracks on pipes, especially on the safety injection system, have been detected on multiple reactors. The investigations continue while, Wednesday, April 20, at the end of the day, barely 30 reactors on 56 were in operation.
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Does France have to fear a generic problem for all of its nuclear park, the main source of electricity in the country? A corrosion phenomenon – called “under constraint” – worries the sector for several months already. In issue, cracks on reactor pipes, especially on their safety injection system. An important part: thanks to bounded water, this backup system is intended to cool the primary circuit in case of accident.
Controls have already detected cracks on five reactors, between the second half of 2021 and the beginning 2022: two to Civalers (Vienna), two in Chooz (Ardennes) and one in Penly (Seine-Maritime). On April 14, on its website, the Electricity Group of France (EDF) carried out a discreet update of the situation. At least four other reactors could be concerned: in Flamanville (Manche), Golfech (Tarn-et-Garonne), Cattenom (Moselle) and Chinon (Indre-et-Loire). For each of them, a doubt remains, after checks “by ultrasound on portions of piping”, specifies the briefing note. The investigations are continuing to “characterize the nature and origin” of these indications.
In other words: subject to complementary expertise, the problem could affect all levels of the French nuclear park. This is already the case for all models of 1,450 megawatts (MW) – those of Civaux and Chooz, the latest and most powerful -, as well as at least one reactor of 1,300 MW – in Penly, in the meantime The conclusions for those of Flamanville, Golfech and Cattenom. The question could also, with Chinon, extend to the category of 900 MW reactors. Ie the oldest and most widespread, since 32 of the 56 reactors of the nuclear park fall under this power.
“Cutting and expertise in the laboratory”
Organizations responsible for nuclear safety in France are kept from any hasty conclusion. “The result of ultrasonic control confirms the need to cut off the welding to study it in the laboratory,” says Julien Collet, Deputy Director General of the Nuclear Safety Authority (ASN). “This cut, carried out by EDF and authorized by the ASN, will begin by at the end of April for laboratory expertise that we will have the results of May.”
The presence of echoes revealed by ultrasound does not necessarily mean the existence of cracks. “It is too early to find out if all the park reactors are affected by the phenomenon of co-ordered corrosion,” says Karine Herviou, Deputy Director General of the Radiation Protection and Nuclear Safety Institute. “The echo can be linked to corrosion under stress, with a particularity of the piping, or to other types of degradation,” says Collet. “Today, EDF does not have a non-destructive control device adapted to corrosion under stress, it is essential to wait for cutting and laboratory expertise,” he adds.
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