Extreme Heat and Low Water Levels Disrupt European Nuclear Power Production

Extreme heat and record low water levels in the Danube have severely limited production at the Paks nuclear power plant in Hungary, where only one of four turbine units remained operational during a recent peak. The facility, which typically provides about 40 percent of Hungary's electricity, faced a brief risk of complete shutdown because water levels dropped below the intake pipes of the cooling pumps. Additionally, environmental regulations limit the temperature of water discharged back into the river to protect aquatic life, often requiring operators to throttle production when river temperatures approach 30 degrees Celsius.

Data from the Paks region shows that the plant typically raises the Danube's water temperature by approximately 1.5 degrees Celsius about 25 kilometers downstream. During the recent production drop, this temperature difference decreased to nearly zero, illustrating the plant's thermal impact on the river. These conditions raise concerns for the planned Paks II expansion, as current heat waves suggest new blocks would also struggle to operate at full capacity during summer months.

France also experiences heat related production losses, though they are smaller on an annual basis. Between 2000 and 2022, annual losses were estimated at less than 1 percent of total production. However, short term fluctuations are significant. In late June and mid July 2026, available capacity was temporarily limited by eight to nine gigawatts, representing up to one fifth of France's normal summer nuclear capacity. Despite these restrictions, grid operators reported that France maintained sufficient reserves and remained a net electricity exporter. While these reductions do not always create an overall shortfall, they can lead to short term price surges and grid instability as air conditioning increases demand across Europe.