Danube Drought Cuts Hungary Power

The Danube fell so low last week that Hungary lost almost all its nuclear power, Romania came within days of losing its last operating reactor, and governments across the region started asking factories to stand down so households could keep using electricity.

How a river switches off a reactor

A nuclear plant needs river water to remove waste heat: it is the cold side of the system that turns nuclear heat into electricity. If the river drops too far, pumps cannot draw enough water. If the water is already warm or moving slowly, the water discharged back into the river can push downstream temperatures above legal limits. In a drought, both limits arrive together.

At Paks, Hungary's only nuclear station and normally a 2,000 MW source, the shutdown came step by step. State energy company MVM began reducing output when the Danube fell past -106 cm at the plant gauge (MVM Paks). By 2 August, only one of eight turbogenerators was still running, at roughly 240 MW (Portfolio, Telex). AP reported a full shutdown (AP). On either reading, Hungary lost most of the nuclear baseload that usually runs day and night.

Romania is in an even narrower position. At Cernavoda, Unit 1 was already offline. Unit 2 remained connected, but the supply basin stood at 2.02 metres, only 12 centimetres above the point where pumps stop working (Ziua de Constanta). A side channel near the Bala canal was drawing about 85% of the Danube's flow away from the plant's cooling intake. The military used controlled explosions to push water back towards the plant (Radio Constanta), buying an estimated four to five more days (Agerpres).

Solar covers midday, not the evening

Romania's daytime figures look comfortable enough. On 3 August the country generated 6,009 MW against 5,212 MW of demand, with solar covering more than 45% (Agerpres). But sunset changes the picture. Solar drops out while air conditioning continues. By the evening of 31 July, Romania was producing 5,239 MW, consuming 7,177 MW, and importing 1,938 MW to cover the difference (Radio Timisoara). That is where missing nuclear power starts to hurt.

This is the part of the story Maltese readers will recognise from a different angle. Malta does not have a Danube or a nuclear plant, but it does know what dependency on interconnectors means. Europe links national power markets through high-voltage cables that move electricity from cheaper zones to more expensive ones. When Hungary and Romania both needed replacement power during the same evening hours, those cables became the constraint.

Slovenia's grid operator ELES limited cross-border capacity on the Austrian border for 3 August (ELES). Wholesale prices rose past €150/MWh, with evening peaks near €270/MWh, well above normal summer levels (Serbia Energy).

Factories absorb the hit so households don't

Both governments made the same choice: industry first, households last. Hungary's emergency decree gave grid operator MAVIR the power to cut or disconnect large industrial and commercial users, while protecting households until the end of the queue (HVG). Prime Minister Péter Magyar said large consumers had committed more than 630 MW of voluntary reductions by 3 August (Telex). That is useful, but Paks normally supplies 2,000 MW. Voluntary cuts cannot replace it on their own.

Romania followed the same logic. Carmakers Dacia and Ford voluntarily stopped production until 19 August, freeing about 200 MW (Agerpres). Nuclearelectrica, which runs Cernavoda, warned customers it may not be able to meet delivery contracts (ZF).

Household bills are protected for now by fixed contracts. That protection is real, but it is being paid for elsewhere: by factories that stop work, by imports over crowded cables, and by grid operators managing a shortage hour by hour. Every megawatt cut from production means delayed cars, disrupted supply chains and losses that surface later.

The system held through the weekend. If the rivers stay low, voluntary savings may become compulsory rationing. The political test is whether replacement power at €270/MWh remains cheap enough for governments to keep shielding households while industry carries the first losses.