Kozloduy Nuclear Plant Cuts Output as Danube Levels Hit Record Lows

The ministry described the move as the first output reduction in the plant’s 52-year operational history, attributing it to “extreme meteorological and hydrological conditions” that have caused the Danube River to fall to levels not seen in decades.

The Straits Times

Kozloduy relies on Danube water to cool the steam condensers in its non-nuclear sections; the river is not used for direct reactor cooling. A shore-based pumping station, built to maintain water supply even at low levels, has been strained as the river’s flow receded across western and central Europe. Similar drought-driven constraints have already forced Hungary’s Paks plant to cut production and led Romania to shut down the Cernavoda nuclear plant in mid-August.

Greenline Romania Moves to Safeguard Nuclear Plant on Record Low Danube The Straits TimesRomania is taking new measures to raise the water level in the Danube to cool the nuclear power plant Danube Drought Slows Bulgaria's Kozloduy Nuclear Plant Bulgaria’s Kozloduy nuclear plant cuts output amid falling Danube levels

• August 13 – Romania shuts down the Cernavoda plant.

Romania Moves to Safeguard Nuclear Plant on Record Low Danube

• August 20 – Bulgaria’s Energy Ministry announces Kozloduy will reduce output by roughly 120 MW.

Bloomberg

• August 21 – Kozloduy implements the 120 MW reduction at Unit 5.

Greenline

• August 23 (scheduled) – Hungary plans to bring turbines at the Paks plant back online.

The Straits Times

• Kozloduy operates two reactors, each rated at 1,040 MW.

Bloomberg

• The 120 MW cut represents roughly 12 % of Unit 5’s capacity and about 6 % of the plant’s total generating capability.

Greenline

• The plant supplies about one-third of Bulgaria’s electricity.

Bloomberg

• Bulgaria’s grid flexibility is supported by over 5 GW of battery storage and significant solar generation.

Danube Drought Slows Bulgaria's Kozloduy Nuclear Plant

• Romania’s emergency response includes releasing an additional average of 50 m³/s from Olt River reservoirs for five days.

Romania Moves to Safeguard Nuclear Plant on Record Low Danube

The Energy Ministry emphasized that the reduction is a preventive safety measure and noted that forecasts predict a continued downstream decline in Danube levels upstream of the Bulgarian section. It also said Kozloduy’s pumping infrastructure was designed for low-water conditions, but the current drought exceeds those parameters.

Bloomberg

Romanian authorities announced emergency dredging near Cernavoda, construction of a groyne to divert additional flow, and temporary water releases from hydro-reservoirs.

Romania Moves to Safeguard Nuclear Plant on Record Low Danube

The Danube’s record low flow is disrupting energy production across multiple countries. With nuclear output curtailed in Bulgaria, Romania and Hungary, regional electricity markets have felt price pressure, and river transport of fuel and bulk goods has slowed. Bulgaria’s reliance on battery storage and solar capacity has mitigated the immediate supply shortfall, showing growing flexibility in the Balkan power grid.

Danube Drought Slows Bulgaria's Kozloduy Nuclear Plant

Sources differ slightly on the exact capacity of each Kozloduy reactor: some describe each unit as having “just over 1,000 MW,” while others specify “1,040 MW.” The Energy Ministry projects a continued downward trend in Danube levels, but quantitative forecasts for the duration of the reduction are not disclosed.

Bloomberg

Romania’s National Committee for Emergency Situations plans emergency dredging and the construction of a water-diverting groyne near Cernavoda. Hungary expects to restart its Paks turbines on August 23, aiming for full output within the following week. Bulgaria’s Energy Ministry has not announced a timeline for lifting the Kozloduy reduction, indicating the decision will depend on future river-level observations.

Greenline