French Nuclear Output Curtailed Amid Heatwave Triggers Power Price Surge

A heatwave sweeping France in early August is forcing the country's nuclear fleet to reduce output, prompting a sharp rise in day-ahead electricity prices. A Reuters report scheduled for August 11 notes that French day-ahead power prices are projected to jump 21.8 % to €142.5 per megawatt hour (MWh), while the German benchmark is expected to rise 22.8 % to €138.50 /MWh. EDF data indicate that nuclear generation will be limited by 7.3 gigawatts (GW)—about 12 % of France’s total nuclear capacity—at the midday peak on Wednesday.

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France derives roughly 70 % of its electricity from nuclear power. The current heatwave, the fifth extreme spell of the summer, has driven river water temperatures upward and lowered river levels, reducing the ability of reactors to use water for cooling. French environmental rules cap the temperature of water discharged into rivers, so operators must curtail output when river water becomes too warm. Similar constraints have already forced Hungary and Romania to shut down their sole nuclear plants earlier this month because of historic low Danube levels.

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• Price impact: +21.8 % to €142.5 /MWh in France; +22.8 % to €138.50 /MWh in Germany (Reuters, scheduled August 11).

Reuters

• Generation cut: 7.3 GW curtailment, representing 12 % of France’s nuclear fleet (EDF data cited by Reuters).

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• Units offline: Two French reactors fully offline, four with output limits, and one additional unit constrained by low river flow.

Reuters

• Heatwave intensity: The heatwave is expected to peak from Wednesday to Friday, with the highest temperatures projected for that period (Kpler analyst Alessandro Armenia).

Reuters

• “The extreme temperatures also amplified widespread drought,” — Dr Samantha Burgess, deputy director of the Copernicus Climate Change Service

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• “Climate change is increasingly bringing the kinds of hot and dry conditions that favour large, high-intensity wildfires in southern Europe while extending the fire season northwards,” — Laurence Rouil, director of the Copernicus Atmosphere Monitoring Service (CAMS) at ECMWF

The Independent

The heatwave is forecast to remain intense through the end of the week, with temperatures expected to stay in the mid-30s °C across much of France. French authorities have warned that water-use restrictions now cover nearly 70 % of the country’s territory, prioritising healthcare, sanitation and drinking water. Continued high river temperatures could force additional nuclear units offline, sustaining pressure on electricity markets in France and its neighboring countries.

Reuters