DOSSIER. Nucléaire : canicule, maintenance, fissures… comment le parc de centrales se retrouve sous tension

DOSSIER. Nucléaire : canicule, maintenance, fissures... comment le parc de centrales se retrouve sous tension

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Several nuclear reactors have been forced to reduce their production due to the high temperatures of the water courses used for their cooling. This situation comes on top of maintenance delays, aging power plants, recently discovered cracks and EPR delays in the context of the global energy crisis.

At a time when the world is plunged into an energy crisis caused by the war in Ukraine, French nuclear energy – capital in the production of electricity since it represents around 67% of total production – is a cause for concern.

covid and cracks

For several months, the fleet of 56 nuclear reactors, which are aging, has been under stress. The concerns began with the Covid-19 epidemic, which interrupted the usual plant maintenance schedule (10-year inspections). Consequences: the availability of the nuclear park was lower than average since the successive confinements transferred the maintenance of certain reactors to the winter period, forced to stop.

French nuclear power plants
DDM – Philippe Rioux

Another setback, the discovery of cracks in October 2021 in an emergency cooling circuit of reactor No. 1 of the Civaux plant. This discovery led EDF to shut down this reactor and then eleven others for safety checks (Civaux 2, Chooz B1 and B2, Penly 1, Chinon B3, Bugey 3 and 4, Cattenom 3, Flamanville 1 and 2, Golfech 1). The Institute for Radiological Protection and Nuclear Safety (IRSN) has described this phenomenon as “pernicious” because it is difficult to detect at an early stage, and the Nuclear Safety Authority (ASN) has judged that it is “a serious event without precedents whose complete treatment will require several years”…

EDF, ASN and IRSN considered that this austenitic stainless steel stress corrosion cracking phenomenon was unprecedented, but the Global Chance association, in a report published on June 15, revealed that such a phenomenon already occurred in 1998 and that there were even precedents. it took place at American power plants in 1975. ASN counters that the 1998 and 2021 cracks are of a different nature.

These fissures are also reminiscent of those that, of another type, will affect future next-generation EPR reactors, including the one at Flamanville. Could these problems finally force a review of the ten-year extension of the 32,900-megawatt-MW reactors, initially designed to last 40 years?

The impact of the heat wave

Along with these problems that led to the closure of 48% of the fleet and, therefore, to predict a drop in electricity production forecasts, EDF is facing a heat wave this summer. Last week, several EDF nuclear reactors were forced to reduce their production due to the high temperatures of the waterways used for their cooling. Each plant has its own regulatory limits for water discharge temperature that must not be exceeded, so as not to heat the surrounding watercourses and protect the fauna and flora. In fact, power plants pump water to cool the reactors, before discharging it. The decrees that set the discharge limits also provide for higher thresholds “in exceptional weather conditions”, as is currently the case at Golfech.

Also read:
Rise in water temperature: “The Golfech plant is not a problem” according to Migado, who monitors fish farming

“The current exceptional weather conditions are causing an increase in the temperature of the Garonne, which has reached 28 degrees,” EDF said on August 5. “At the request of the operator of the national electricity network (RTE), the production unit No. 2 of the Golfech plant remains in production (minimum power)” (300 MW, compared to 1,300 MW), continues EDF; the first reactor is undergoing maintenance…*

“RTE identifies the need to maintain the Blayais, Bugey, Golfech, Saint-Alban and Tricastin nuclear power plants at a minimum level of electricity production until August 21 to guarantee the security of the electricity network,” explains the ASN, which is why has adopted on August 4 a decision that temporarily modifies the thermal discharge limits of these plants until September 11, 2022 “accompanied by reinforced monitoring of the aquatic environment, in particular the life of fish. »

Also read:
Nuclear: the Garonne and its fish monitored like milk in the fire downstream of the Golfech nuclear power plant

Because these water discharges from the power plants worry the fishing and environmental defense associations. “That doesn’t mean it prevents damage. It is in the long term that we will see it ”, worries Roland Desbordes, spokesman for the Criirad.

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