Record-low Danube forces Paks reactor off Hungary grid
Unit 3 at the Paks nuclear plant went offline at 3 p.m. on Wednesday, a second unit is running at half power, and Prime Minister Peter Magyar says the whole plant may stop by Friday.
The Paks nuclear power plant in southern Hungary took its third unit off the grid on Wednesday because the Danube no longer carries enough water to cool it. Nothing like it has happened since the plant started operating. It is the same river that pushed three Serbian towns into a state of emergency this July and cut output at the Iron Gates 1 hydro plant to a third, only further upstream, on a stretch where almost half of Hungary’s electricity depends on the gauge reading.
What happened at Paks
The shutdown of Unit 3 began at 3 p.m. on Wednesday, July 29, 2026. The Danube at the plant stood at minus 118 centimetres, and the operator, MVM Paks Nuclear Power Plant Ltd, took the decision once the river reached that mark, in line with operational and environmental safety requirements. By Thursday morning the gauge read minus 121 centimetres.
Output did not collapse in one step. The operator had been trimming it for days before the unit left service altogether, and on Thursday a second unit was brought down to 50 percent. Antal Kovacs, the plant’s communications director, told Telex that nothing of the kind had occurred before.
This has never before happened in the history of the nuclear power plant.
Kovacs also said the plant had not been prepared for water levels like these. In a sector that plans in decades, that sentence carries more weight than the number on the gauge.
Why does a nuclear plant need a high Danube?
Paks draws Danube water for cooling and returns it to the river, and regulations cap the temperature of the discharge. As the channel holds less and less water while air temperatures climb, the warm outflow disperses more slowly and the legal limit is reached sooner. The only way to stay inside it is to cut power, and if that is not enough, to take the unit off the grid.
The Budapest gauge shows how far the problem reaches. On Tuesday, July 28, it registered between 30 and 31 centimetres, an all-time low for that station.
Half the country’s power in one place
Paks runs four units with a combined capacity of roughly 2,000 megawatts and supplies just under half of Hungary’s electricity. Prime Minister Peter Magyar announced on Thursday that the entire plant could be shut down either that day or on Friday, insisting supply would hold because Hungary can import between 3,600 and 3,800 megawatts.
Economy and Energy Minister Istvan Kapitany said the temporary shortfall would be covered by domestic renewables and higher imports, and that the grid remains stable. On the consultations under way, he said:
The most qualified energy experts in the country are sitting down together today so that every decision is taken in good time and in full coordination.
Pumps, cranes and a heat alert
Equipment is already in position near Paks in case the river keeps falling:
- four floating pumping units
- two floating cranes
- 55 specialists on standby around the clock
Pumping has not been switched on yet. Across the country, 66 of 84 water management districts have been placed on extraordinary readiness, and bottled water is being handed out at major transport hubs. A level 3 heat alert runs from Thursday through Tuesday with highs of 36 to 37 degrees Celsius, which means no relief for the river for at least a week.
Environment Minister Laszlo Gajdos said protective measures were under way and that Hungary’s water resources and national security were being safeguarded.
What it means for Serbia
We have written this week about the lowest Danube in half a century, the state of emergency in three Serbian towns and the drop at Iron Gates 1 to a third of capacity. The Hungarian case is the other side of the same problem: one drought, one river, a reactor instead of a turbine.
The practical consequence can already be named. If Hungary pulls as much as 3,800 megawatts off the regional market in the same week that hydro plants on the lower Danube are running weak, the squeeze on supply is felt across Central and South-East Europe, Serbia’s peak-hour balance included. Imported power in July costs the most precisely when everyone wants it at once.
A decision on the two remaining units at Paks is expected by Friday, July 31, with gauge readings published daily.
