Bulgaria's Kozloduy NPP Reduces Power Generation: Low Danube Water Levels Pose Risks to Regional Energy Security

On 8 October, Bulgaria's Kozloduy Nuclear Power Plant began a scheduled shutdown of Unit 6, with a capacity of approximately 1,000 MW, for maintenance and nuclear fuel refuelling. The works are expected to be completed by the end of November 2026.

Meanwhile, Unit 5 remains operational, although its output continues to depend on the Danube's water level and the plant's ability to secure sufficient cooling water. As of 8 October, the unit's gross power output stood at 917 MW.

In recent months, the plant has repeatedly reduced electricity generation due to declining water levels in the Danube. In August, Unit 5's output was reduced by approximately 120 MW, while in early October, restrictions affected both units.

Commentary by the Institute of Danube Research

The situation at Kozloduy NPP demonstrates that prolonged low water levels in the Danube are evolving from a transport and logistics problem into a complex challenge to energy security in Central and Southeastern Europe.

Declining water levels affect not only navigation and port operations but also the functioning of strategic energy infrastructure. Restrictions on nuclear power generation may increase pressure on regional electricity systems and the need for cross-border electricity supplies.

For Ukraine, this trend is particularly significant given its integration into the European electricity market and the growing interdependence of energy systems across the Danube region.

The Institute of Danube Research emphasises that water security in the Danube basin is becoming an increasingly important determinant of regional energy resilience. This requires coordinated hydrological monitoring, modernisation of power plant cooling systems, and a common approach to adapting critical infrastructure to climate change.

Low water levels in the Danube are no longer solely an environmental or transport issue — they are becoming a strategic factor in regional energy security.