Heatwave: EDF shuts down two more reactors at Nogent-sur-Seine and Bugey

EDF, France's state-owned energy company, has shut down two additional nuclear reactors amid a heatwave, citing environmental concerns related to rising river temperatures. The reactors at Nogent-sur-Seine and Le Bugey were taken offline to ensure compliance with regulations on thermal discharge into waterways.

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On Thursday, June 25, 2026, around 10:30 a.m., production unit No. 1 of the Nogent-sur-Seine nuclear power plant was shut down due to the increase in the temperature of the Seine.

This action follows the earlier shutdown of a reactor at Golfech earlier in the week. The reactor at Nogent-sur-Seine, located on the banks of the Seine River, was stopped on Thursday morning due to "external causes related to the environment." EDF stated this measure is necessary to respect the limits for heating the river, thereby protecting aquatic ecosystems.

Similarly, a reactor at the Bugey plant in the Ain region was shut down on Thursday afternoon. This decision was made in anticipation of the Rhône River's temperature reaching 26 degrees Celsius. EDF aims to prevent excessive warming of the river by limiting the temperature difference between the water drawn for cooling and the water returned to the river.

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From Tuesday, June 23, 2026, due to the temperature of the Seine, the power of reactor No. 2 of the Nogent-sur-Seine plant is being adjusted to comply with regulations on thermal discharges. This adjustment is made to limit the heating between the water drawn and the water returned to the Seine and thus preserve aquatic fauna and flora.

In addition to these shutdowns, EDF is adjusting power production at several other sites. For instance, the second reactor at Nogent-sur-Seine is having its power output reduced to manage thermal discharge into the Seine. These measures highlight the challenges nuclear power plants face in maintaining operations during extreme weather events like heatwaves, requiring careful management to balance energy production with environmental protection.

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To comply with regulations [...], in anticipation, production unit No. 3 of the EDF Bugey nuclear power plant was shut down on Thursday, June 25, 2026, at 10:15 a.m. Unit No. 2 is undergoing scheduled maintenance, and units No. 4 and 5 are connected to the national electricity grid.