The Blayais nuclear power plant (Gironde) was forced last week to slow down its activity. In question ? The temperature of the water discharged by EDF into the Garonne which exceeded the limit of 30° C.
The situation, which is rather common during summer heat waves, only rarely occurs in May.
As a result of climate change, periods of drought are becoming longer and more frequent in France. In this month of May, 16 departments are under water restriction, according to the Propluvia platform, under the aegis of the Ministry of Ecological Transition.
This Monday, May 9, this state of drought caused the slowdown of one of the four reactors of the Blayais power plant, in Gironde. According to EDF, “the power was reduced from 900 MW to 100 MW for a few hours”. In some cases, the phenomenon requires reactor shutdown. We then say that the plant is “decoupled” from the network, that is to say put in a “safe” state before it is put back into operation.
An unusual measure in the spring
The Blayais nuclear power plant, located at the Gironde estuary, pumps water from the Garonne to cool its production units. But in agreement with the Nuclear Safety Authority, the discharge of this heated water must be limited in temperature so that the river does not exceed 30 ° C in winter regulations and, from May 15, 36.5 ° C. .
However, the rise in mercury in recent weeks has caused a crossing of the regulatory 30° C, forcing EDF to curb production. On its website, the company indicates that “production restrictions are likely to affect the nuclear production fleet […] until Sunday May 15.
Great start for our annual industrial program! This night, the production unit n°2 will be stopped to proceed, soon, to the reloading of its fuel. An essential step to continue the production of neutral electricity in #CO2. pic.twitter.com/AffA3vYYq8
— EDF Blayais (@EDFBlayais) March 11, 2022
This measure, less and less rare in summer, is unusual so early in the year. She is one of the many witnesses of the consequences of global warming on French territory. The pessimistic forecasts of the IPCC, which foresee an increase in average temperatures of 2.5°C by 2100, have experts wondering about a potential upheaval in the production of energy from nuclear power.
Production shouldn’t be really affected
An idea that is gaining ground among some activists and politicians, including Jean-Luc Mélenchon, who believes in a tweet that nuclear power could be an “intermittent” energy. However, according to several experts and reports, the production of power plants should be only slightly affected by climate change.
This is explained by the French manager of the Electricity Transmission Network (RTE) in an in-depth study of February 2022. Entitled “Climate and the electricity system”, the report describes the “possible paths to transform the electricity system with a view to achieve carbon neutrality.
In a sub-section devoted to the nuclear fleet, RTE indicates that “the sensitivity of nuclear reactors to meteorological variables strongly depends on their geographical location (seaside, river or river), but also on their cooling system”. Indeed, a power plant by the sea (Flamanville, Penly) will have fewer heated water constraints than production near a river (Blayais).
Later in the text, it is specified that 90% of “production losses due to so-called climatic unavailability were thus concentrated on 4 of the 18 sites” in operation. Over one year, the loss of energy is estimated at “less than 1%”. This is enough to put concerns about electricity production into perspective.
The situation will change in a few years
But the situation should change in the coming years, with the worsening of global warming. Rising temperatures, over a longer period, could affect production cycles. “For sites on the banks of the river, with unchanged regulations and without adaptation of existing installations, the risks of unavailability of units should increase”.
In a graph, RTE estimates that certain power stations could see their loss be multiplied by four (Cattenom, in Moselle), even by 10 (Golfech, in Garonne). All these forecasts are to be taken with precaution because they are only hypotheses.
In 2022, in France, in a context of soaring energy prices, 27 nuclear reactors out of the 56 we have will be shut down, a record. The health crisis has postponed the maintenance operations which are being held simultaneously today. But with a sharp drop in demand in the summer, the risk of a cut is extremely low.