Record Droughts Shut Nuclear Plants in Hungary and Romania, Testing EU Energy Security

Why a Record-Low Danube Has Taken Paks and Cernavoda Offline

A record drought across Central Europe has forced nuclear reactors in Hungary and Romania to shut down, in a striking illustration of how even power sources marketed as weather-independent can be tripped up by climate stress. The Danube has fallen to levels not seen in living memory, with Budapest's gauge at around 10cm on Monday, far below the previous all-time low of 33cm recorded in 2018. Nuclear plants depend on river or sea water to condense steam and keep reactor cores within safe limits, and both countries' facilities are now caught short.

Hungary's only nuclear station, the Soviet-era Paks plant, generates roughly half of the country's electricity and is facing its first inactivity in 44 years. Prime Minister Péter Magyar said the next five days would be 'the most critical,' warning that the power grid, public services and households would come under enormous strain, and that the plant may not be fully functional for weeks. Households and businesses are already volunteering to cut electricity demand.

In Romania, the Cernavoda plant, two 706MW reactors supplying about 20% of national electricity, faces the same problem. The National Institute of Hydrology measured Danube inflow at 1,600 cubic metres per second against a typical July average of 4,700, with forecasts pointing below 1,500 before the drought eases. Acting Prime Minister Ilie Bolojan declared a nationwide state of alert in the energy sector, and the navy carried out controlled underwater detonations near Izvoarele to blast rock and redirect remaining water toward the plant.

The stress extends well beyond the Danube basin: the Rhine in Cologne has fallen below its 2018 record low, Rotterdam water levels are down about 10%, Italy's Po basin is in a state of high water scarcity, and Serbia's main hydroelectric plant is running at a fifth of capacity. The episode raises new questions about whether riverside nuclear facilities are future-ready as Europe warms roughly twice as fast as the global average, according to the Copernicus climate service.

Cooling Water, Grid Strain and the Nuclear Resilience Debate

The Cooling-Water Math Behind Paks and Cernavoda

The mechanics are straightforward: nuclear reactors need a constant supply of river or sea water to condense steam and keep the core within safe temperature limits. Budapest's gauge at around 10cm, compared with the previous record low of 33cm in 2018, and Romania's measured inflow of 1,600 cubic metres per second against a July norm of 4,700 both point to the same constraint: there is simply not enough water to maintain normal cooling. The shutdown at Paks, its first in 44 years, is therefore not a mechanical failure but a hydrological one.

Why Hungary's 50% Nuclear Share Changes the Stakes

Paks supplies roughly half of Hungary's electricity. When a single plant with that market share is impaired for weeks, voluntary demand cuts can soften but not replace the shortfall. Prime Minister Péter Magyar's warning of 'enormous strain' on the grid and public services is consistent with a system that has little spare capacity. Romania, where Cernavoda provides about 20% of demand, has more room to manoeuvre, yet still needed a nationwide state of alert and an extraordinary navy operation near Izvoarele to redirect water.

Nuclear's Reliability Argument Meets a Regional Drought

This episode cuts directly at nuclear's core selling point: that it runs day and night regardless of weather. That claim now has a caveat. Researchers from McMaster University, writing in a forthcoming Energy Policy paper, argue adaptation is part of nuclear's DNA, citing cooling towers, dry cooling technologies, adaptive scheduling and climate-informed reactor designs. They also note that all energy sources operate under constraints, whether thermal discharge limits for nuclear or intermittency for renewables. The implication is not that nuclear is unviable, but that its vulnerability to water stress must be managed and priced like any other infrastructure risk.

One Drought, Several Countries, No Easy Imports

The same weather system is squeezing the Rhine, the Po and Serbia's hydro capacity. Cologne has seen levels below its October 2018 record low, Rotterdam is down about 10%, Italy's Po basin is in a state of high water scarcity, and Serbia's main hydro plant is at a fifth of capacity. Because the hydrological stress is regional, affected countries cannot simply lean on neighbours for power, a point that will sharpen EU debates about interconnected grids and climate resilience.

Next Steps for Grid Operators and Policymakers in the Danube Basin

• Stress-test river-cooled plants against 2026 conditions. With Budapest water at about 10cm and Danube inflow at 1,600 cubic metres per second versus a 4,700 July average, operators should model intake and discharge limits at even lower flows and pre-plan load reductions before the next heatwave.
• Line up substitute capacity in Hungary now. Paks supplies about 50% of electricity and may be impaired for weeks; the grid operator should firm up imports, standby thermal generation and demand-response contracts ahead of the 'most critical five days' flagged by the prime minister.
• Treat navy blasting as a stopgap, not a solution. Cernavoda needs a durable intake resilience plan, whether deeper intakes, dredging or dry cooling, rather than repeated underwater detonations at Izvoarele.
• Coordinate cross-border emergency measures. The same drought is cutting Danube and Rhine flows for Hungary, Romania, Serbia and Western Europe; a regional early-warning and power-sharing protocol would help before forecast flows approach 1,500 cubic metres per second.
• Expect short-term price pressure. With two large nuclear plants constrained, utilities will likely run more expensive backup generation; consumers in the region should heed official requests to cut demand during peak evening hours.
• Document the outage for regulators and insurers. Paks's first inactivity in 44 years will invite scrutiny of cooling-water dependency, so operators should prepare a clear climate-risk and mitigation record.