Romania Shuts Its Last Working Nuclear Reactor As Record-Low Danube Triggers Energy Emergency
Romania’s last working nuclear reactor is being shut down after the Danube fell to record lows
Romania has begun shutting down its last operating nuclear reactor after the drought-stricken Danube fell too low to provide the cooling water needed for normal operation.
The controlled closure of Unit 2 at the Cernavodă Nuclear Power Plant means both of the country’s reactors are now offline simultaneously—removing a facility that ordinarily supplies approximately one-fifth of Romania’s electricity.
This is not a nuclear accident, nor evidence that the reactor has become unstable. It is a preventative safety decision. But it represents a serious energy shock at the worst possible moment: hydropower production is also being squeezed by drought, extreme heat is increasing electricity demand and neighbouring countries are confronting many of the same problems.
Romania must now replace roughly 1,400 megawatts of dependable nuclear capacity using fossil fuels, renewable generation and potentially expensive electricity imports.
Romania’s Final Reactor Begins Controlled Shutdown
State-owned nuclear operator Nuclearelectrica started shutting down Cernavodă Unit 2 on Thursday, 13 August, after monitoring the continuing decline of the Danube and the reactor’s operating parameters.
Unit 1 had already been taken offline on 28 July under the plant’s severe-drought procedures.
Each of Cernavodă’s two CANDU reactors has a capacity of approximately 706MW. Together, they ordinarily account for about 20 per cent of Romania’s electricity production.
Nuclearelectrica emphasised that the shutdown was being conducted in a controlled manner and that nuclear safety had not been compromised. Romania’s Energy Ministry similarly said national electricity requirements would continue to be covered through other domestic sources and imports.
The situation nevertheless leaves Romania without any operating commercial nuclear generation until the river recovers sufficiently for at least one reactor to restart. Reuters and the Associated Press both confirmed that the second controlled shutdown had begun.
Why A Nuclear Reactor Depends On A River
A nuclear reactor produces heat through nuclear fission. That heat is used to create steam, which turns a turbine and generates electricity.
The process also requires an effective cooling system. At Cernavodă, water drawn from the Danube plays a central role in removing heat through the plant’s cooling circuit and condensing steam after it passes through the turbines.
The reactor does not simply stop requiring cooling because the river is low. Instead, operators must ensure that enough water can be drawn into the system while remaining within approved operating and environmental limits.
When water levels fall too far, intake systems can no longer function reliably under their normal design conditions. Higher river temperatures can create an additional problem by making the available water less effective at absorbing heat.
The controlled shutdown therefore prevents the plant from being pushed beyond the hydrological conditions covered by its safety procedures.
It is important to distinguish this from an emergency reactor trip or an accident. Operators are deliberately reducing the reactor’s power, disconnecting it from the grid and moving it into a safe shutdown state.
The Danube Has Fallen To Extraordinary Lows
A prolonged combination of extreme heat, limited rainfall and drought has pushed the Danube to exceptionally low levels across Central and Eastern Europe.
At the point where the river enters Romania, measurements have reportedly fallen to a new recorded low.
During July, the flow reaching Cernavodă dropped to approximately 1,630–1,750 cubic metres per second. The long-term July average is around 4,700 cubic metres per second, meaning the river was carrying little more than one-third of its usual seasonal volume.
The Danube is Europe’s second-longest river, flowing through or alongside ten countries. Its decline is consequently affecting far more than one Romanian power station.
Low water levels have reduced hydropower production, complicated commercial shipping and placed pressure on industrial and municipal water systems. Austria’s principal hydropower company reported that its output during the first half of 2026 was 32 per cent below the long-term average. Reuters reported that the river’s flow near one Austrian power station had fallen from a typical 2,000 cubic metres per second to around 700.
Romania’s nuclear shutdown is therefore one dramatic symptom of a much larger regional water crisis.
Romania Tried Extraordinary Measures To Save The Reactor
Authorities did not surrender Cernavodă’s remaining reactor without a fight.
Romanian teams dredged parts of the riverbed, removed a submerged rock obstruction using explosives and sank barges filled with rock in an attempt to redirect more water towards the plant’s intake channel.
The intervention was remarkable: military engineers were effectively reshaping part of the Danube to keep the country’s most important power station operating.
The work temporarily improved conditions and was initially expected to buy Unit 2 several additional days of operation. But it could not overcome the continuing decline in the river.
As forecasts deteriorated, Nuclearelectrica concluded that a controlled shutdown was necessary.
The failure of such drastic emergency engineering demonstrates the scale of the drought. Romania did not close its last reactor because it lacked uranium, trained staff or generating equipment. It closed because one of Europe’s greatest rivers could no longer provide sufficient water under the plant’s approved operating conditions.
Will Romania Face Blackouts?
A nationwide blackout is not the expected outcome.
Romania has declared an energy alert covering August and assembled several measures to replace lost nuclear output. These include bringing a 330MW lignite-fired generating unit into service, maximising available wind and hydropower production and importing electricity through cross-border connections.
The country reportedly has approximately 4,000MW of cross-border import capacity, although the amount actually available at any moment depends on market conditions, transmission constraints and the needs of neighbouring grids.
Prime Minister Ilie Bolojan previously identified Ukraine, Bulgaria and Greece as possible sources of additional electricity.
Officials have also asked households and companies to reduce voluntary consumption, particularly during the evening peak when solar production declines but air-conditioning and domestic demand can remain high.
The government has established a mechanism allowing grid operator Transelectrica to restrict consumption by large industrial users if the supply situation becomes critical. Electricity exports could also be reduced or suspended. Balkan Green Energy News reported that these powers were adopted as protection against more severe shortages.
For now, Romania appears to possess enough alternative generation and interconnection capacity to keep its grid operating.
However, that does not mean the shutdown will be painless.
Imported electricity can be significantly more expensive during periods of regional scarcity. Replacing nuclear generation with coal or lignite also increases emissions, while industrial restrictions could reduce economic output.
The immediate danger is therefore more likely to emerge through higher costs, reduced energy security and pressure on industry than through households suddenly losing power nationwide.
The Cruel Energy Paradox
Romania’s response exposes an uncomfortable energy paradox.
Nuclear power is one of the largest sources of low-carbon electricity available to the country. Yet drought and extreme heat have forced its entire nuclear fleet offline, leading the government to activate a lignite-fired power station.
In other words, weather conditions associated with a warming climate have temporarily removed low-carbon generation and encouraged greater reliance on one of the most carbon-intensive fuels.
That does not mean nuclear power is inherently incompatible with a changing climate.
Nuclear stations can use cooling towers, reservoirs, seawater systems or hybrid cooling technologies that reduce their exposure to a single river. New plants can also be designed around more conservative assumptions about water availability and temperature.
The Cernavodă crisis instead shows that cooling infrastructure designed around historical river conditions may become less dependable when those conditions change.
Romania has planned a hydrotechnical project worth approximately $225 million to strengthen the plant’s access to water, although the work has reportedly suffered delays. Engineers and policymakers will now face intense pressure to accelerate it.
Hungary Is Fighting The Same Battle
Romania is not confronting the Danube crisis alone.
Hungary’s Paks Nuclear Power Plant, which normally supplies nearly half of the country’s electricity, has also been forced to slash production because of low river levels.
At its weakest point, the 2,000MW plant was operating at little more than 10 per cent of capacity. A modest increase in the Danube allowed one turbine to be restarted, but output remained severely restricted.
Hungary is preparing major river-engineering work involving a submerged barrier and as much as 145,000 cubic metres of rock. The proposed structure is intended to raise the water level near Paks by up to 1.2 metres.
Officials estimate that reduced output at the plant could cost Hungary approximately $158 million every month. The emergency river works themselves are expected to cost around $19 million. The Associated Press reported that the government is trying to prevent the first complete shutdown of Paks in more than four decades.
The parallel crises matter because neighbouring countries often depend on one another during electricity shortages.
If Romania, Hungary and other regional markets are simultaneously importing power, the supply available to each country becomes more expensive and less certain.
Does This Undermine Europe’s Nuclear Expansion?
The shutdown will inevitably be used by nuclear power’s opponents as evidence that reactors are vulnerable to climate change.
That argument contains some truth, but it needs qualification.
Any large thermal power station—including nuclear, coal and gas facilities—must dispose of waste heat. Plants dependent on rivers can become constrained when water is too low or too warm. Hydroelectric power is even more directly exposed to drought, while gas and coal generation remain vulnerable to fuel prices and disrupted supply chains.
Wind and solar have different weaknesses: their output changes with weather conditions and time of day unless supported by storage, interconnection or dependable backup generation.
There is no energy source entirely free from environmental or infrastructural risk.
The stronger lesson is that countries require diversified systems and must build power stations for future climatic conditions rather than the averages of the past.
Romania still plans to extend the life of Cernavodă Unit 1, complete Units 3 and 4 and develop small modular reactors. Hungary is proceeding with its Paks II expansion.
Those projects are unlikely to be abandoned because of one severe drought. But their cooling arrangements will now face far greater scrutiny.
Future reactors may need larger cooling towers, hybrid dry-and-wet cooling systems, redesigned intake channels or additional stored-water reserves. These measures cost money and can reduce efficiency, but they may be necessary to preserve dependable nuclear output during increasingly severe summers.
When Can Cernavodă Restart?
The reactors can be restarted once Danube conditions recover sufficiently and the operator confirms that all technical and safety requirements can be met.
The decisive factor will be sustained rainfall across the river’s vast upstream catchment—not merely a brief shower near the plant.
A temporary rise may improve the intake situation without providing enough confidence for a restart. Operators will need to consider river forecasts, flow rates, water temperature and the risk that levels could fall again shortly after reconnection.
That makes the shutdown’s duration uncertain.
If substantial rain returns, one reactor could potentially resume operation relatively quickly after the necessary inspections and restart sequence. If the drought persists, Romania may remain without nuclear generation for weeks.
Europe Has Received A Warning From The Danube
The sight of Romania closing its last working nuclear reactor because the Danube has fallen too low would once have appeared extraordinary.
In 2026, it has become part of a wider regional struggle involving emergency imports, industrial power reductions, lignite generation and increasingly desperate attempts to redirect a shrinking river.
Romania’s electricity system is not collapsing. The shutdown is controlled, the grid has alternatives and officials insist that consumer demand can be met.
But the margin for error has narrowed.
The deeper warning reaches beyond Romania. Europe’s energy infrastructure was designed around assumptions about river flows, rainfall patterns and summer temperatures that may no longer be dependable.
Cernavodă will eventually restart. The harder question is whether its next shutdown can be prevented before the Danube falls this low again.
