Two centimetres keep Cernavodă on the grid

Romanian military divers detonated a rock formation in the Danube on 3 August, raising the water level near Cernavodă by about two centimetres (Euronews România, Financial Intelligence). At Cernavodă, Romania's only nuclear plant and its largest source of steady electricity, two centimetres can mean another day of cooling water. The river had been dropping 2-3 cm daily, and the plant was roughly four to five days from losing enough flow to keep running (AGERPRES).

Hungary shows what happens when cooling water runs out. Paks, which normally supplies roughly half the country's electricity (World Nuclear Association), shut down progressively from 27 July after the Danube fell too low for the pumps that pull cooling water from the river. By 2 August, only one of eight turbogenerators was still running (MVM). Both countries asked factories to cut consumption so households could keep the lights on.

Engineering the river

The Pârjoaia rock sat near a fork where the Danube splits into the Old Danube, which feeds Cernavodă's cooling intake, and the Bala Branch, which had been pulling away most of the remaining flow. The blast was the most visible part of a broader effort: crews dredged the silted intake channel and sank four stone-loaded barges as a temporary underwater wall (Curs de Guvernare, Libertatea). The government set aside about 7 million lei for the work, a modest sum for emergency river engineering but far cheaper than replacing Cernavodă's output with imports.

Energy Minister Radu Miruță claimed about +4 cm after the water propagated downstream (Digi24). The full package aims for 10-12 cm of gain (HotNews). But the river keeps falling. Hydrologists forecast the Danube at Baziaș could drop to 1,350 m³/s by 10 August, below the 1,400 m³/s historic minimum recorded in 1985 (AGERPRES). The blast bought time. It did not change the forecast.

Hungary's missing megawatts became everyone's price problem

During one peak hour on 4 August, Hungary drew 3,195 MW from imports against 3,049 MW of domestic generation. More than half the country's electricity came from abroad (Portfolio).

That sudden demand raised prices across the region. Central and south-eastern European grids are linked through cross-border auctions: when one country needs more power than it generates, it bids for imports, and the price rises for every connected zone. By 29 July, day-ahead prices (the price set in auctions the day before power is delivered) in the Hungarian-Serbian corridor averaged €132/MWh, with hourly spikes hitting €268/MWh (Serbia Energy). Forward contracts for the following week climbed into the €250-263/MWh range (Argus). Replacing 2 GW of nuclear capacity with spot imports during a heatwave, when air conditioning pushes demand higher everywhere, is expensive. The forward prices show traders expected the squeeze to last.

Not every plant is equally exposed

Bulgaria's Kozloduy nuclear plant draws cooling water through a pumping station set in a deep bay, a less exposed arrangement than Cernavodă's open channel. Bulgaria's energy ministry said it expected no significant reduction for at least three weeks (BTA). Austria offers the sharpest contrast. VERBUND, the country's biggest hydropower operator, reported first-half 2026 generation 9.8% below the previous year (VERBUND), yet Austria still exported power in June (APG). Austria had enough other generation capacity and grid flexibility to absorb the same drought.

Romania can buy days with barges and dredging. It cannot keep treating cooling water as an emergency fix if hotter, lower summers keep returning.