European nuclear output falls sharply as record drought and heatwave force reactor shutdowns across France, Hungary, Romania, and Slovenia

A sustained European heatwave combined with record low river levels forced nuclear output reductions and full shutdowns at plants across the continent in late July and early August 2026. France closed three reactors after drought conditions cut river flows to the point where plants could not draw sufficient cooling water, while Hungary shut its sole nuclear plant entirely. Romania took the extraordinary step of deploying its navy to blast rocks on the Danube and sink weighted barges to divert water towards the Cernavoda nuclear facility, having already closed one of two reactors the previous week. Slovenia reduced reactor output due to high temperatures and low flows on the Sava River. Serbia saw output at its largest hydropower plant fall to just 20 per cent of capacity, pressing the government to import electricity from abroad. Separately, a wildfire swept through Dunwich Heath in Suffolk at the end of July, burning the equivalent of 210 football pitches just north of the Sizewell B nuclear plant, which powers up to 2.5 million British homes. The European Union depends on nuclear power for approximately a quarter of its electricity needs and a third of its low-carbon electricity, a share that grew by nearly five per cent between 2023 and 2024. In March 2026 the EU committed a further €330 million to accelerate fusion energy and support nuclear technologies. The physics of the problem is structural: low river levels prevent plants drawing sufficient cooling water, while high ambient temperatures restrict how much warm water can be discharged back, and regulatory waivers cannot substitute for water volume.