Hungary’s 2,000 MW Paks nuclear power plant could be forced to halt electricity generation after record-low Danube levels threatened the operation of its cooling-water intake system.
The plant normally supplies about half of Hungary’s electricity and forms the core of the country’s baseload generation. A complete shutdown would therefore create an immediate need for higher imports and thermal replacement at a time of elevated summer demand.
Although the Danube still contains sufficient water for cooling, the river is approaching a level at which the intake pumps may no longer be able to draw water into the plant. Operators have started lowering the intake structures in an attempt to maintain access.
Water levels are reportedly 28 centimetres below the previous record low measured in 2018 and more than one metre below the minimum level used when the plant was designed more than four decades ago. The scale of the deviation shows that the issue is no longer a conventional seasonal fluctuation but a structural operating risk.
The plant attributes the decline to long-term riverbed erosion, upstream sediment retention, historical dredging and increasingly frequent climate extremes. The absence of significant spring flooding in 2026 left the river unusually low before the summer demand period began.
Paks uses four alert levels for low-water conditions. It is operating under Level 3, with Level 4 requiring all reactors to shut down. Management indicated that this threshold could be reached within 24 to 72 hours, depending on river conditions.
A reactor shutdown would reduce cooling-water demand sharply. Normal generation requires approximately 100 cubic metres per second, while maintaining safe cooling after shutdown needs only around 5 cubic metres per minute. The operator has stressed that reactor safety can be maintained for an extended period even if the low-water period persists.
The power-market consequences are more immediate. Reduced Paks output has already pushed Hungary towards much heavier imports from Austria, Slovakia and Romania. A full shutdown would tighten Romania, Bulgaria, Slovenia, Croatia and Serbia as cross-border capacity is redirected towards the Hungarian deficit.
The risk has also moved into forward prices. Hungarian week-ahead power has developed an exceptional premium over Germany and Italy, reflecting the possibility that the nuclear constraint will persist into early August.
The physical problem may ease within days if river levels recover, allowing reactors to return to service. The deeper issue will remain: an asset supplying roughly half the country’s electricity is operating with a cooling-water system designed for Danube conditions that no longer provide a reliable lower boundary.
