France curtails nuclear output by 6.4 GW amid extreme heatwave

An intense heatwave raised river temperatures across France, prompting the state‑owned utility EDF to shut down three nuclear reactors—Golfech 2, Bugey 3 and Chooz 2—and to limit output at up to eight additional units. The curtailment removed about 6.4 GW of capacity, roughly 14 % of the country’s electricity demand at the time.

France’s nuclear fleet, which supplies around 70 % of national electricity, remained a net exporter, with more than 10 GW still slated for export to neighboring countries. The reductions were driven by environmental regulations that limit the temperature of water discharged back into rivers, protecting aquatic life. A temporary regulatory waiver allowed Bugey to operate slightly above the usual thermal limit until mid‑July. No safety incidents or power outages were reported.

The episode underscores the vulnerability of nuclear generation to extreme weather and highlights the balancing act between energy security, climate goals and river ecosystem protection.