Extreme Heat Disrupts France’s Nuclear Power Generation as Three Reactors Shut Down Temporarily

Dragon Media News Desk

A severe heat wave sweeping across Europe has significantly affected nuclear power generation in France. As river temperatures rose beyond environmental limits, state-owned energy company EDF temporarily shut down three reactors and reduced output at several others.

According to EDF data, power generation from eight nuclear reactors was reduced by a combined 6.3 gigawatts on Monday morning. The reduction was equivalent to around 14 percent of France’s total electricity demand at the time.

The affected units included Saint-Alban 1 and 2, Bugey 3, 4 and 5, Golfech 2, and Blayais 1 and 3. Golfech 2 and Bugey 3 were completely offline on Monday morning, while the remaining reactors were operating at reduced capacity.

As the heat intensified, EDF confirmed the temporary shutdown of Golfech 2, Bugey 3 and Chooz 2. Together, the three reactors have a combined capacity of 3.65 gigawatts, representing nearly six percent of France’s total installed nuclear capacity of around 61 gigawatts.

EDF said the shutdowns and output reductions were not caused by nuclear safety failures but were necessary to protect rivers and aquatic ecosystems.

Nuclear power plants use river water to cool reactors and other equipment before returning the heated water to the river. When river temperatures are already unusually high, releasing additional warm water can harm fish and other aquatic life.

Under French environmental regulations, EDF must reduce reactor output or temporarily halt operations when river temperatures exceed prescribed limits.

The company said the reactors were technically capable of operating during high temperatures and clarified that the latest restrictions were not related to mechanical or safety problems.

The Golfech nuclear plant draws cooling water from the Garonne River, while the Bugey and Saint-Alban facilities rely on the Rhône River.

High temperatures combined with limited rainfall have reduced river flows, affecting both the availability of cooling water and the capacity to discharge heated water safely.

Preliminary schedules indicate that Bugey 3 could remain offline until July 19, Golfech 2 until July 22 and Chooz 2 until July 25.

EDF said the dates could be revised depending on weather conditions and changes in river temperatures.

Despite the substantial reduction in nuclear output, France’s overall electricity supply is not considered to be at immediate risk, according to data from national grid operator RTE.

France was still able to export more than 10 gigawatts of electricity to neighbouring countries on Monday.

RTE has previously said that France retains sufficient generation capacity to meet domestic demand even when several reactors are affected by hot weather.

The grid operator estimates that each one-degree Celsius increase in temperature can raise electricity demand by around 0.7 to one gigawatt because of increased use of air-conditioning systems.

France generates a major share of its electricity from nuclear power. As a result, simultaneous reductions at several reactors can influence not only the domestic power system but also electricity markets and prices in neighbouring European countries.

During an earlier heat wave in June, French electricity exports fell from between 10 and 12 gigawatts to around three gigawatts. Wholesale electricity prices in France and Germany also climbed to their highest levels since January 2025.

Although solar power output generally rises during hot and sunny weather, production falls sharply after sunset. This increases dependence on nuclear, wind and gas-fired generation during the evening.

Energy analysts have warned that European power systems could face additional pressure when higher electricity demand and lower nuclear or hydropower generation occur at the same time.

EDF said annual nuclear production losses caused by high river temperatures and reduced water flows have historically remained limited.

Since 2000, such conditions have reduced France’s annual nuclear output by an average of only 0.3 percent, according to the company.

However, increasingly frequent and prolonged heat waves and droughts have raised the need to adapt energy infrastructure to more extreme weather conditions.

EDF plans to invest €8.7 billion over the next 15 years to strengthen the climate resilience of its nuclear, hydropower and other energy facilities.

The programme includes improvements to cooling systems, technologies designed to reduce the temperature of discharged water and measures to enhance the ability of power plants to operate under extreme weather conditions.

The latest disruption in France shows that although nuclear energy remains a major source of stable and low-carbon electricity, its operation is closely linked to river flows, water temperatures and environmental limits.

As heat waves become more intense and prolonged, European countries may need to manage a more difficult balance between electricity generation, environmental protection and rising demand for cooling.