Exceptionally low water levels along the Danube River are disrupting nuclear power production in Romania and Hungary, placing additional strain on electricity grids already facing increased demand during an intense summer heatwave.
Lower river flows reduce the water available for cooling and limit the Danube’s capacity to absorb heat discharged by power plants. Operators must cut production or shut reactors down when these conditions threaten equipment or environmental limits.
Hungary’s Paks Nuclear Power Plant began reducing output on July 27. By July 30, its four reactors were operating at less than half of their combined capacity of about 2,000 megawatts. The plant normally supplies close to half of Hungary’s electricity.
Hungarian Prime Minister Péter Magyar warned that Paks could be completely shut down on July 30 or 31 if the Danube continued to fall. The government said electricity imports could compensate for the lost generation, although greater dependence on neighboring markets could increase costs and expose Hungary to regional supply pressures.
Romania Shuts Down One Reactor
Romania’s state-controlled nuclear operator, Nuclearelectrica, shut down Unit 1 at the Cernavoda Nuclear Power Plant after extremely low water levels threatened equipment associated with its cooling system.
The company initially announced that Unit 2 would also be disconnected. However, after reviewing operating conditions overnight, Nuclearelectrica said on July 30 that the reactor could temporarily remain connected to the national grid.
The company cautioned that Unit 2 might still need to be shut down at any moment if river conditions deteriorate. Unit 1 will remain offline until the Danube rises sufficiently for the reactor to operate safely.
Cernavoda’s two reactors each have a capacity of approximately 706 megawatts and together normally provide around 20 percent of Romania’s electricity. Losing even one reactor increases the country’s reliance on imported power at a time when air-conditioning use is driving demand higher.
Danube Falls to Record Low in Budapest
In Budapest, the Danube dropped to 23 centimeters, breaking the previous record low of 33 centimeters measured in 2018.
Farther downstream, the river’s flow entering Romania fell to around 1,650 cubic meters per second, compared with a typical July average of approximately 4,750 cubic meters per second. Water levels in Romania had already reached their lowest point since 1996.
The decline has also disrupted cargo shipping, ferries and river cruises along one of Europe’s most important waterways.
The disruption highlights a growing vulnerability in Europe’s energy system. Nuclear and thermal power plants designed around reliable river flows are increasingly being tested by hotter summers, prolonged droughts and rising competition for water—conditions scientists expect climate change to intensify.