Shutdown of Nuclear Power Blocks: Record Heat Puts Energy Supply Under Pressure

Europe is caught in a record heatwave, and the power grid is being pushed to its limits as many people try to cool off with fans and air conditioning. However, some power plants will not be operational to handle this additional load.

France recorded its hottest day since records began in 1947 on June 23, with temperatures soaring above 44 degrees, and they remained unusually high even at night. This persistent heat has led to an increase in water temperatures in several rivers across the country — and to a problem for the many nuclear power plants that use these waters for cooling. One reactor has already been shut down, others are being throttled back, or will face restrictions throughout the week.

Shutdown of the Nuclear Power Plant – A Precautionary Measure

Block 2 of the Golfech Nuclear Power Plant in southern France was shut down on June 22 at around 11:45 PM when the river used for cooling the plant became too hot. This was a precautionary measure, said Brid Nelligan, a spokesperson for the French electricity company EDF, which owns and operates the plant.

The plant draws water from the Garonne River and returns most of it back to the river after cooling the facilities at a slightly higher temperature. Since French regulations limit the temperature of this return flow, the high water temperature, which was expected to reach 28 degrees, forced the operator to shut down the plant.

EDF, which also operates the entire French nuclear power fleet, has also reduced the output of other reactors across the country. A reactor at the Nogent-sur-Seine plant was already throttled back on June 23, with more expected to follow throughout the week, according to Nelligan.

Extreme heat has previously impacted the French nuclear industry. According to data from Ember Energy, during a heatwave in July 2025, nuclear power plants across the country with a capacity of at least seven gigawatts had to be shut down. This is more than the total electricity supply of Ireland.

This time, the outages and power restrictions of the plants are not expected to be so drastic that they would affect the coverage of electricity demand in France, according to RTE, the operator of the national power grid.

Not Only Nuclear Power Plants Affected, But Also Hydropower, Coal, and Natural Gas Plants

Nuclear energy has made the most headlines during this heatwave, but other forms of electricity generation are facing similar challenges. Hydropower plants often struggle when drought reduces the amount of water available for power generation, forcing them to throttle back or shut down operations. In the first five months of last year, high temperatures and low water levels led to a 13 percent decrease in hydropower supply in Europe compared to the previous year.

Even established coal and natural gas plants can face challenges due to high temperatures. Hot weather can strain the facilities and limit the efficiency of cooling towers. Five gas plants in the United Kingdom have reported production declines due to the conditions, reducing power supply by a total of about 2.5 gigawatts.

Energy Consumption for Cooling Will Double

The increased demand is largely due to cooling needs and is, according to Jean-Paul Harreman, director of the energy information service Montel, the main factor putting pressure on the European power grid. Even countries that have rarely relied on cooling technologies in the past are now turning to them — the number of households in the United Kingdom using air conditioning has roughly doubled since 2022.

Globally, the challenges that heat poses to the power grid are expected to worsen as climate change leads to more frequent and intense heatwaves. According to the International Energy Agency, energy consumption for cooling is expected to double worldwide by 2050 compared to 2023 levels.

"Energy providers can adapt by planning for summer peak loads, making cooling needs more flexible, reinforcing grids for high temperatures, utilizing batteries and load management, and making the cooling systems of power plants climate-resilient," explains Simone Tagliapietra, Senior Fellow at Bruegel, an economic and political think tank.

However, these changes could be costly. Earlier this year, EDF released an assessment of its company's vulnerability to climate change, including nuclear and hydropower plants across France. The modernization measures are expected to cost around 600 million euros per year over the next 15 years.