EDF Takes Reactors Offline at Nogent, Bugey and Golfech as France Records Its Hottest Day
EDF has temporarily shut down nuclear reactors at the Nogent-sur-Seine plant on the Seine and the Bugey plant on the Rhône as river temperatures rose during a record heatwave, Euronews reported on 25 June 2026. A reactor at the Golfech plant on the Garonne in south-western France had been taken offline earlier in the week, and output was reduced at several other sites across EDF's 57-reactor fleet. Météo-France reported that Wednesday 24 June was the hottest day recorded in France since national measurements began in 1947.
French nuclear plants located on rivers draw water to cool their reactors and return it to the river slightly warmer. EDF said earlier in the week that it had reduced output on one of the Nogent reactors "to limit the temperature increase between the water withdrawn from the Seine and the water discharged back into it, thereby protecting aquatic plant and animal life." Reuters reported on 18 June that EDF had warned high river temperatures were expected to limit output in the following week, naming Golfech, Blayais and Bugey among the plants at risk.
According to a report citing EDF data, reductions in nuclear output reached about 4.1 GW on 24 June, roughly 7% of midday demand. French grid operator RTE said on 24 June that "France has sufficient generation capacity to meet electricity demand, including in the event of outages at certain production facilities." Nuclear power accounted for close to 70% of France's electricity generation in 2025, according to Euronews, and France has been a large net exporter of electricity since its nuclear fleet recovered from the corrosion problems and outages of 2022.
Summer heatwaves coincide with strong solar output, which helps offset reduced nuclear generation during the day. Plants on the Rhône and Garonne are particularly exposed, because these rivers are warmer and their summer flows are more variable. The French nuclear safety authority has said that the operating limits are environmental rather than safety limits.