EDF faced with nuclear reactor failure

EDF faced with nuclear reactor failure

.’s dark streak continues EDF. Thursday, January 13, the group announced that the fourth nuclear reactor, Penly 1, in Seine-Maritime, has been affected by a corrosion problem in the safety injection system – a device of critical importance in the event of an accident. The closure has been extended until the end of May. Reporter assess the situation.

  • How many reactors are affected by this problem ?

This corrosion problem has been detected in four reactors: the 1,450 MW reactors 1 and 2 (MW) from the Civaux (Vienne) power plant, reactor B2 from 1450 MW de Chooz (Ardennes) and thus reactor 1 of 1300 MW from Penly.

All parts have been sealed pending replacement of defective parts and will remain unavailable for several months. According to the latest news, Civaux 1 should restart on August 31 and Civaux 2 on December 31. Chooz 2 won’t be back in service until December 31. For the Penly 1, it will only be reconnected on May 30th.

The Chooz B1 reactor has also been closed until at least February 11, withoutEDF Do not reveal that she is affected by this problem. « Checks and experience are still in progress (…) It will continue until a full evaluation is obtained », the group wrote to Reporter. Nuclear Safety Authority (NSC)ASN), wrote to Reporter That Chooz B1 was also experiencing this wear defect and that it would not be restarted until July 27.

  • What glitch are we talking about? ?

Civaux 1, 2, Chooz B2 and Penly 1 showed wear and small cracks at the junction of their initial circuit and safe injection system. The primary circuit carries the water that cools the reactor core made up of the vessel and the nuclear fuel it contains. As for the safety injection circuit, it makes it possible to inject perforated water into the primary circuit in case of a breach and water loss in the latter. The goal: to avoid fuel overheating and core melting – which occurred during the Chernobyl and Fukushima accidents.

More specifically, it’s a file « stress erosion », explains to Reporter Karen Hervio, Deputy Director General of the Institute for Radiation Protection and Nuclear Safety (IRSN). This is « A localized corrosion phenomenon that occurs under the influence of mechanical stress and in an aggressive chemical environment – in this case, the fluid of the primary circuit contains chemical elements such as boron ».

Seafox 1 nuclear power plant. © ASN

This deterioration was unlikely. « In the nuclear industry, selection is made from materials that are neither sensitive or not at all sensitive to stress corrosion, contact mI Hereview. But the welding processes generate residual stresses in the material. They are carried out according to very specific processes aimed at reducing the creation of these stresses, and after welding, stress relief processes are applied to reduce it further. » For the five reactors involved, these precautions were clearly not enough.

Deputy General Manager ofIRSN He also referred to this phenomenon as « malignant » : « You may not see anything during the so-called incubation stage, which can last for twenty, thirty or forty years. This explains why EDF He may not have seen anything during previous scans. Then, a small defect will occur, a small crack that develops according to mechanical limitations. »

  • How is this erosion phenomenon explained? ?

This is the great unknown. « EDF Offer several leads (circuit engineering, welding) that need to be checked », the Nuclear Safety Authority wrote to Reporter. « This is an unexpected phenomenon for this type of steel at this site and the reasons for these defects are not well understood today. », as explained by Julian Colette, deputy general manager ofASNAgence France-Presse.

« 100 to 150 cases of stress corrosion have been reported worldwide, of very diverse origins, which do not necessarily shed light on the understanding of what is happening in French power plants. », indicates on her part mI Hereview.

However, hypotheses have already been excluded. « Feedback on international experiments shows that this phenomenon is independent of reactor age and is not related to aging », sets the deputy general manager ofIRSN. In fact, the plants in question are also the most recent and last in operation: 1997 and 1999 for the Civaux reactors, 1996 and 1997 for the Chooz reactors and 1990 for the Penly reactor.

« EDF Can’t explain to us exactly what’s going on »

A vigil committee was organized on Tuesday January 11th by the local media authority (CLI) from Civaux to learn more about this decline. ExplanationsEDF Leave members hungry. « EDF He just told us it’s not a heat stress problem, which occurs when very hot water and very cold water circulate alternately through circuits, nor is it a vibration problem. But he cannot explain to us exactly what is happening », He said Reporter Helen Heinz-Shimuel, a member of CLI The Scientists Group for Information on Nuclear Energy (GSIEN).

This uncertainty affects the electrician’s morale. « We feel they are very concerned, weI Heinz Schmuel. They were less comfortable than usual and were embarrassed when answering “We can’t tell you” To our many questions. We felt their instability. »

  • Is this a general problem ?

The French nuclear fleet in operation consists of fifty-six reactors of approximately the same model produced in succession, although with different powers (900, 1300) MW and 1450 MW). We are calling « general anomaly » A defect that will appear in all reactors of the same power level – eg in all 1450 . reactors MW… – or even on all the reactors in the fleet. « At this point, a general issue cannot be ruled out », we loveI Hereview.

What is certain is the discovery of a corrosion phenomenon in one of the 1300 . Penly reactors MW Not good news for EDF. This means that this problem is not limited to 1450 MW, as previously expected EDF.

It remains to be seen if the other 1,300 reactors will be MW affected by this defect. For now, the group has decided not to shut down the reactors at this power level. Instead, it has proceeded to review all results of previous checks that have been performed on these fixtures and is preparing a verification program that will be communicated toASN end of January. « There will definitely be checks to be done in the coming months. (Some may be done) during normal shutdowns – the reactors will have inspections for ten years, and they will obviously be subject to specific checks. The question to be looked at with the control program is the need to make early or off-schedule closings »Mr. Colette explainedFrance Press agency.

  • What are the financial consequences of these closures EDF ?

« Impact on financial prospects [de ces arrêts] being analyzed », books EDF Thursday January 13th in a press release.

One thing is for sure, the cost of the kit promises to be significant. « At Civaux, a non-functioning reactor represents a shortfall of 1 million euros per day », dit United StatesI Heinz Schmuel. daily reverberation Transferring the first estimates to many economic analysis offices. Barclays analysts estimate that Ebitda [1] It will be reduced by 5.5 billion in 2022. For Citi, the bill could be as high as 7 billion. JP Morgan offers a range of 5 billion to 10 billion, depending on the evolution of market prices.

This, in the context of the government’s request on Thursday, January 13th, to make an effort of about 8 billion euros EDF To help it contain the electricity price hike to 4 % (see our article). Friday early in the session, after this series of bad news, work EDF decode more than 20 %. At the end of the day, the loss was 14.59 %.

  • What are the consequences of power outages this winter? ?

There, too, these anomalous discoveries come at worst, in the middle of the winter cold. On Thursday evening, 10 of the 56 reactors were closed, i.e. 20 % of French production capacity. Alone, four reactors of 1450 MW At the station in Civaux and Chooz is 10 % of this capacity. Thursday evening, EDF It lowered its forecast for nuclear production for 2022 to 300-330 TWh, from 330-360 TWh previously.

« In winter, the availability of the nuclear fleet has never been this low »HV Network Manager Books RTE to me Reporter. However, « The shutdowns of the five reactors do not add to the security of supply restrictions as they have already been considered closed throughout the winter ». RTE It had already warned of electricity supply tensions in its forecast note on December 30. New forecasts should be sent at the end of the month.

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