Danube States Move to Harden Power Grids After Summer of Nuclear Shutdowns
Record low river levels knocked nearly 1 GW of nuclear capacity offline across Romania and Hungary, driving Balkan spot prices close to EUR 187/MWh and forcing a coal restart.
Governments along the Danube moved on Friday (2026-09-04) to strengthen power-system drought procedures, Montel reported, as the summer's extended low-water conditions demonstrated how quickly a single river system can disable a regional electricity market.6
The push follows a summer in which Romania's Cernavoda nuclear plant lost both its operating reactors to cooling-water shortages. Each unit carries 680 MW of installed capacity, and together they normally account for about 20% of Romania's electricity supply. The second and final unit shut on August 13 (2026-08-13), according to Jurist.org, leaving Romania without any nuclear generation for the first time in years.5,4
The outages began in late July. Nuclearelectrica announced a controlled shutdown of Cernavoda Unit 1, rated at 650 MW, early on Tuesday (2026-07-28), after severely depleted Danube levels triggered the plant's drought procedures, the company said. Hungary faced concurrent cooling-water constraints. Combined regional nuclear losses reached nearly 1 GW by the end of that month, Montel reported.1
Spot power prices moved fast. By Monday (2026-08-03), with roughly 40% of the region's nuclear capacity knocked offline, the benchmark Hungarian hub had reached EUR 186.90/MWh — close to double its pre-drought level, Montel data showed.2
The European Commission said on Tuesday (2026-08-04) it was "closely" monitoring risks to southeast European power supplies and stood ready to call an emergency meeting if conditions deteriorated further. A Commission spokeswoman gave no specific trigger threshold for that meeting. The statement signaled concern without offering a concrete backstop, leaving regional operators to manage short positions with limited visibility on Brussels' next move.2
Romania's government responded by restarting the Rovinari Group 4 coal unit, a 300 MW plant, during the week of August 17 (2026-08-17), OilPrice reported. The restart was a partial fix at best. Cernavoda's combined installed capacity runs to 1,360 MW, meaning the coal unit replaced less than a quarter of the lost nuclear output on a nameplate basis, and considerably less in practice given typical plant output factors.4
The climate dimension is direct. TechTimes reported in late July (2026-07-29) that the Danube fell to an all-time low. River-cooled reactor designs carry a specific constraint: their availability declines during prolonged heat and drought, the same conditions that push power demand higher. Operators and grid planners have long acknowledged the risk in principle; this summer showed it playing out at scale across two countries simultaneously.3
Both Romania and Hungary operate reactors dependent on Danube cooling, and both found their drought contingency procedures inadequate for the length and severity of this year's conditions. That is the problem the regional governments, per Montel's Friday (2026-09-04) reporting, are now attempting to correct — whether through reservoir arrangements, minimum-flow agreements with upstream states, or pre-approved fuel-switching protocols is not yet detailed in available reporting.6,1
Cernavoda's restart timeline is the immediate signal for the market. Until both units return, Romania carries no nuclear generation, and any additional dry weather through September extends the outage into the autumn peak demand period. The coal-fired Rovinari unit provides partial cover, but 300 MW does not restore system adequacy for a country that normally draws a fifth of its power from a single riverside plant.5,4