Romania shuts down Cernavodă nuclear reactor Unit 1 as Danube reaches record-low water level

Summary

Romania's state nuclear company Nuclearelectrica shut down Unit 1 of the Cernavodă Nuclear Power Plant on July 27-28 after the Danube River fell to what authorities described as a historically unprecedented low water level. The plant uses Danube water for cooling; below a threshold level, it cannot operate safely. An emergency energy command was convened by Romanian authorities. The shutdown is the first nuclear outage at Cernavodă directly caused by river water scarcity. Unit 1 supplies roughly 5% of Romania's electricity, and its loss tightens the country's power balance during summer peak demand. Cernavodă runs two CANDU reactors and normally covers about 20% of Romanian power output between both units.

The split

Romania Insider and The Diplomat Bucharest both framed the shutdown primarily as a climate-linked infrastructure event, not a nuclear safety incident; Romanian-language coverage (Adevarul, Stiripesurse) emphasised the convening of the emergency energy command as a sign of institutional preparedness. No source reported radiation concerns or an uncontrolled shutdown. The Danube's record-low level follows weeks of extreme heat across the EU's southeastern states.

By the numbers

• ~5%, Unit 1's approximate share of Romania's electricity output
• ~20%, combined share of both Cernavodă CANDU units in normal output
• 1, reactor unit shut down (Unit 2 remained operational)
• Unprecedented, the Danube water level descriptor used by Nuclearelectrica in its official statement

Why it matters

Cernavodă is Romania's only nuclear plant and a baseline electricity source that the country relies on for grid stability and EU power exports. A prolonged shutdown in peak summer demand tightens Romania's power balance and raises spot electricity prices across the Balkan interconnection. The event illustrates a widening category of climate-driven infrastructure risk: rivers no longer reliably supply nuclear cooling water.

What to watch

• Whether Danube water levels recover quickly enough for a restart of Unit 1
• Whether Romania activates emergency imports from neighbouring EU grids
• Whether the EU triggers any coordination mechanism for cross-border power shortfalls
• Whether the incident prompts Nuclearelectrica or regulators to set formal Danube minimum-flow thresholds for reactor operation