Romania is dealing with persistently low Danube water levels affecting cooling-water availability at Cernavodă. Cernavodă is described as Southeast Europe’s largest single power availability risk. Emergency engineering measures have been deployed to keep the remaining reactor in operation.
The interventions include dredging, removing underwater obstructions, and positioning rock-loaded barges to redirect Danube water toward the reactor’s cooling-water intake. The work is expected to extend the reactor’s operation by approximately nine to ten days. This replaces an earlier expectation of five to six days.
Cooling-water constraints and potential impact on nuclear output
Danube flows have fallen to roughly one-third of their normal August level. Flows could remain depressed beyond mid-August. A shutdown of the second reactor would remove another 680 MW of dependable baseload capacity.
That would leave the entire 1.36 GW Cernavodă nuclear fleet unavailable. With that capacity removed, Romania would become more dependent on gas-fired generation, coal, electricity imports, and demand-side measures. The shift would be particularly relevant during the evening peak.
System-security actions and cross-border trading exposure
The government has authorised staged reductions in industrial consumption. It could also impose export restrictions if Romania’s adequacy position deteriorates. Such steps would introduce an additional physical-delivery risk for cross-border electricity trading.
Market participants holding commercial transmission capacity from Romania cannot assume exports will remain available if emergency system-security measures are activated. This risk is not confined to Romania’s borders, affecting neighbouring market supply expectations.
Regional supply balance across Moldova, Hungary, Serbia and Bulgaria
Moldova remains heavily dependent on Romanian electricity supplies. Hungary is structurally short and regularly imports more than 2 GW. Serbia can provide exports during selected hours, but its own hydrological position is weak and coal availability remains operationally sensitive.
Bulgaria is currently described as the strongest alternative regional supplier. Its support comes from Kozloduy nuclear generation, lignite-fired capacity, hydropower, and a year-to-date electricity surplus. However, Bulgaria’s ability to compensate for lost Cernavodă output is limited.
Bulgaria cannot simultaneously replace Cernavodă output, meet its own evening demand, and supply every neighbouring market at unconstrained volumes. The overlap of low hydropower availability, nuclear constraints, and extreme weather conditions is cited as increasing the importance of regional flexibility and cross-border security margins across Southeast Europe.
