Hungary’s NPP faces weeks-long shutdown as record-low Danube levels threaten regional power supplies

Hungary’s only nuclear power plant at Paks could remain offline for weeks because water levels on the Danube River, essential for cooling its reactors, are expected to stay critically low, Prime Minister Péter Magyar said on Friday.

The crisis presents an early and unexpected test for Magyar, who took office only in early May 2026 after leading his Tisza party to a landslide victory that ended Viktor Orbán’s 16-year rule. Less than three months into his premiership, the new government must manage a major energy emergency that risks industrial disruption, higher import dependence, and public concern over electricity security – all while Magyar seeks to implement promised reforms, stabilise public finances, and rebuild ties with the European Union.

The plant’s four Russian-designed reactors, which normally supply nearly half of Hungary’s electricity, are already running at less than 50% of their combined 2-gigawatt capacity. Full shutdown is anticipated as early as Monday as river levels are forecast to drop further. Restart will only be possible once water recovers enough for safe operation – something Magyar said is “not expected to happen in the next weeks.”

A concurrent heatwave is projected to lift electricity demand by about 20% during evening peak hours, raising the risk of a critical supply situation. Magyar has urged major industrial consumers, including carmakers and battery producers, to submit voluntary reduction plans. Energy company MOL is already cutting its electricity use by 40% by idling some facilities, while Samsung SDI’s battery plant north of Budapest is reducing water use by 50% and power consumption by 10% in critical periods. Hungary plans to rely on imports to bridge the gap, though regional constraints could limit availability.

Situation in Romania

Neighbouring Romania faces a parallel crisis. Severe drought has driven Danube flows to multi-decade lows, forcing the controlled shutdown of Unit 1 at the Cernavodă nuclear plant earlier this week. Unit 2 has also faced restrictions or temporary disconnection risks, marking the first time both of the plant’s 706-megawatt reactors have been affected simultaneously by low water. Cernavodă normally accounts for roughly one-fifth of Romania’s electricity generation. Domestic production has fallen well short of peak demand (estimated around 7.3 GW), increasing dependence on imports at a time when neighbouring countries are under similar strain.

Romania shuts nuclear reactor as Danube runs dangerously low

Regional electricity grid risks

The Danube drought and heatwave are creating cascading pressures across south-eastern Europe’s interconnected power systems. Reduced nuclear output in Hungary and Romania coincides with lower hydropower generation (including at major facilities such as Serbia’s Đerdap/Iron Gates complex) and higher air-conditioning-driven demand. Countries that typically export surplus power are themselves constrained, raising the prospect of tighter supply balances, elevated wholesale prices, and potential industrial curtailments or emergency measures. Grid operators across the region are monitoring cross-border flows closely as the situation evolves.

Vulnerability of nuclear power plants

Many nuclear plants, particularly older facilities designed decades ago, depend on large volumes of river water for condenser cooling. When water levels fall below the intake elevation of cooling pumps – or when river temperatures rise too high – operators must reduce output or shut units down entirely to protect equipment and maintain nuclear safety margins, as well as to comply with environmental limits on thermal discharges. Historical design assumptions based on past minimum water levels have proved insufficient against the extremes driven by prolonged drought and climate change. While shutdowns themselves are managed safely (residual heat cooling requires far less water than full-power operation), prolonged outages remove large blocks of reliable baseload generation precisely when demand peaks, exposing broader energy-security vulnerabilities in river-dependent systems.

Forecasts continue to show little immediate relief for Danube levels, leaving both national grids and the wider regional electricity market under pressure in the coming weeks.

Edited by g.g.

Caption: A view of the MVM Paks Nuclear Power Plant, which had to close its Reactor 3 due to extremely low water levels on the Danube River, in Paks, Hungary, 29 July 2026. EPA/DANIEL KISS