Hungary nuclear plant survives Danube flood threat by millimetres

Hungary’s only nuclear power plant came within millimetres of an emergency shutdown last week as the swollen Danube river pushed floodwaters to critical levels around the Paks facility, raising serious questions about the long-term safety of the country’s most important energy asset.

How close did it get?

The Danube crested at roughly 8.5 metres near Paks — dangerously close to the threshold that would have triggered an automatic protective shutdown of the four Soviet-era VVER reactors that generate about half of Hungary’s electricity. Plant operators and emergency crews worked through the night reinforcing temporary flood barriers, and by most accounts the margin between normal operation and a forced halt was measured in single-digit centimetres.

That’s not a comfortable buffer for a facility producing around 2,000 megawatts of power.

What officials are saying

Hungarian authorities were quick to insist the plant never faced a genuine safety crisis. “At no point were the reactors or their cooling systems at risk,” a spokesperson for MVM Paks Nuclear Power Plant Ltd said in a statement Monday. “Our flood protection systems performed exactly as designed.”

But critics aren’t satisfied with that framing. Environmental groups and opposition politicians in Budapest argue that “performed as designed” and “came within millimetres of shutdown” are two things that shouldn’t appear in the same sentence when you’re talking about nuclear infrastructure.

A pattern of rising waters

The 2024 flood isn’t an isolated event. Central Europe has seen increasingly severe and unpredictable flooding in recent years, with the Danube breaking records across multiple countries in September alone. Austria, Slovakia, the Czech Republic and Hungary all declared emergencies at various points during the same weather system that pushed the river to historic highs.

Paks sits on the western bank of the Danube roughly 100 kilometres south of Budapest. The plant was commissioned in the 1980s and its original flood-risk assessments were built around historical water-level data that, climatologists now say, is no longer a reliable guide to what the river might do next.

So the question isn’t just what happened last week. It’s what happens in five years, or ten, when the next major flood arrives — potentially bigger.

What comes next for Paks

Hungary is already deep into planning for Paks II, a major expansion project backed by Russian state nuclear company Rosatom that would add two new VVER-1200 reactors to the site. The project has been controversial for reasons ranging from its financing structure to its dependence on Russian technology at a time when Budapest’s ties to Moscow are under intense EU scrutiny.

The flood episode adds another layer of complexity. Regulators and engineers will now face pressure to revisit the flood-risk modelling for both the existing plant and the planned expansion before construction proceeds further.

And if last week proved anything, it’s that climate timelines don’t wait for construction schedules.