Romania has begun shutting down the second and last operational reactor at its Cernavoda nuclear power plant after record-low water levels on the Danube left the facility without sufficient cooling water, removing a major source of electricity from the national grid and increasing pressure on neighboring Moldova.
The controlled shutdown of Unit 2 began on Aug. 13, according to state-owned operator Nuclearelectrica. Unit 1 had already been taken offline in late July because of the same drought-driven decline in Danube water levels. The two reactors, each rated at 706 megawatts, normally account for about 20% of Romania’s electricity generation.
Nuclearelectrica said the shutdown was driven by the continued deterioration in river conditions. The operator also stressed that keeping both reactors safely shut down has no impact on nuclear safety, personnel, the public or the environment.
The development comes as prolonged drought and extreme heat strain electricity systems, waterways and industrial activity across Central and Eastern Europe. The Danube’s exceptionally low levels have already disrupted nuclear generation in Hungary and reduced the river’s capacity to support shipping and other economic activity.
Moldova Faces New Electricity Supply Pressure
The shutdown has immediate implications for Moldova, which relies heavily on electricity imports and has increasingly used Romania’s wholesale market as part of its supply mix.
Romanian electricity imports have been an important source of flexibility for Moldova, particularly during periods of high demand. The loss of Romanian nuclear generation could force Chisinau to seek additional supplies from Ukraine, purchase electricity from Western markets at higher prices or consider electricity restrictions if sufficient alternatives are unavailable.
“I think we should be ready for a worsening situation, including power outages, although it’s hard to say for sure right now,” Moldovan energy expert Sergiu Tofilat told Radio Chisinau.
Moldova’s dependence on electricity imports remains a structural energy-security concern. The Energy Community has described the country as heavily reliant on electricity imports while emphasizing the importance of strengthening domestic resilience and regional integration.
Romania Turns to Alternative Generation and Imports
Romanian authorities have sought to compensate for the lost nuclear capacity through a combination of thermal generation, renewables, hydropower and electricity imports.
The Energy Ministry has activated a 330-megawatt lignite-fired power plant and said additional wind generation and hydropower, where reservoir conditions permit, would help cover the shortfall. Romania has also declared an energy emergency for August and called on consumers to reduce electricity use during peak evening periods.
The government has prepared staged restrictions for large industrial consumers if the electricity system comes under additional pressure. Automakers Dacia and Ford were also expected to pause production in Romania through Aug. 19 as part of efforts to reduce demand.
The Energy Ministry said Romania’s electricity system has roughly 4,000 megawatts of cross-border capacity available for imports.
“The national power grid has a cross-border capacity of roughly 4,000 megawatts to enable electricity imports,” the ministry said in a statement. “All European operators know the regional energy crisis situations and are coordinating to ensure safety in supplying all the grids hurt by weather conditions.”
The ministry said electricity supply would remain covered through alternative generation and imports following the shutdown.
Unprecedented River Engineering Measures
Romanian authorities had attempted to preserve enough water flow for Cernavoda before the second reactor was shut down.
Measures included blasting a rock obstruction near the Bala Canal, dredging sections of the riverbed and sinking rock-filled barges intended to redirect water toward the main Danube channel and the nuclear plant. Despite those interventions, river levels continued to fall below the threshold needed to sustain reactor operations.
The episode illustrates a growing vulnerability for nuclear facilities that depend on large rivers for cooling. Nuclear plants can continue operating during many forms of extreme weather, but prolonged drought can reduce the availability of cooling water or raise its temperature beyond operational limits.
For Romania, the immediate consequence is the temporary loss of its entire nuclear generating fleet. For the wider region, the shutdown demonstrates how a single environmental stressor can simultaneously affect electricity generation, cross-border power markets, industrial production and transportation.
Hungary Faces a Parallel Nuclear Cooling Crisis
Romania is not alone in confronting the problem.
Hungary’s Paks nuclear power plant, which also relies on the Danube for cooling, has experienced severe output reductions as water levels fell. The four-reactor facility normally supplies roughly 40% of Hungary’s electricity generation and has been operating at sharply reduced capacity.
Hungarian authorities have taken extraordinary steps to preserve cooling conditions at Paks. The government has ordered the construction of a submerged riverbed sill and has prepared two 80-meter barges that can be sunk near the plant to raise the local water level.
The measures underscore the regional nature of the problem. Both Romania and Hungary depend on the same river system for critical nuclear infrastructure, meaning exceptionally low Danube flows can create simultaneous stresses on multiple national power systems.
France Also Sees Drought-Related Nuclear Constraints
The effects extend beyond the Danube basin.
France, Europe’s largest nuclear power producer, has also faced restrictions and outages associated with extreme heat and low water availability. Reuters reported that output at several French reactors was affected by weather conditions, while other outages were linked to additional factors, including jellyfish.
The broader European pattern is increasingly relevant to energy-security planning. Nuclear power is a major source of low-carbon electricity, but many existing plants were designed around historical assumptions about river flows and water temperatures. More frequent and intense droughts could challenge those assumptions.
Copernicus data have shown widespread below-average river flows across central and eastern Europe in 2026, including the Danube basin, amid persistent precipitation deficits and worsening drought conditions.
Climate Risk Becomes an Energy-Security Issue
The immediate crisis is rooted in weather, but its strategic implications extend to infrastructure resilience.
The Danube is Europe’s second-longest river, running roughly 2,850 kilometers from Germany to the Black Sea. Exceptionally low flows have disrupted navigation, agriculture and industrial activity in addition to constraining nuclear power generation.
For European governments, the problem is therefore broader than whether individual reactors can remain online. Drought can simultaneously reduce hydropower output, constrain thermal and nuclear cooling, increase electricity demand through air-conditioning and disrupt fuel and industrial supply chains through reduced river transport.
The shutdown at Cernavoda also highlights the growing importance of regional electricity interconnections. Romania can compensate for part of the lost nuclear production through imports, but doing so places additional pressure on neighboring markets at a time when Hungary, Moldova and other countries are confronting their own weather-related energy constraints.
The crisis demonstrates a difficult paradox for European energy policy: nuclear power remains central to efforts to maintain reliable, low-carbon electricity supplies, yet some existing nuclear infrastructure remains dependent on water systems increasingly exposed to extreme drought.
For Romania and Moldova, the immediate priority is maintaining electricity supplies through the remainder of the summer. For European energy planners, the Danube crisis offers a more lasting warning about the need to account for changing hydrological conditions when designing and operating critical energy infrastructure.