The Reactor That Was Never Switched On

The control room at Zwentendorf has the wrong kind of quiet. Everything is where it should be — panels, switches, the analogue dials of the mid-1970s — and none of it has ever done anything. Down in the reactor building the pressure vessel stands open, and visitors are walked inside it, because nothing in this building has ever been radioactive and nothing ever will be.

The plant sits on the south bank of the Danube about forty kilometres west of Vienna, near Tulln. It is a 692-megawatt boiling water reactor, it cost 5.2 billion schillings, it was finished in 1978, and no fuel was ever loaded into it. Other finished reactors have been left cold — Bataan, in the Philippines, has stood unfuelled since 1984 — but Zwentendorf is the only one a country stopped by putting it to a vote. That vote was held on 5 November 1978, and 1,606,777 people voted no against 1,576,709 yes. The margin was 50.47 per cent against 49.53 — around thirty thousand votes out of more than three million cast.

A referendum about the chancellor

Bruno Kreisky, who had governed since 1970 and expected to win, made the vote a test of himself. He said publicly that a no would end his chancellorship. That framing was meant to pull his own party into line and it did the opposite: it handed the opposition a reason to campaign against a technology many of its own people supported, and the People's Party recommended a no. A share of the electorate turned up to vote against Kreisky and switched off a reactor on the way past.

He did not resign. Six months later he won an absolute majority in the general election, which is the part of the story usually left out. Parliament passed the nuclear prohibition act on 15 December 1978. The fuel elements, already bought, were sold on. So were components, to German plants built to the same design, which spent the following decades cannibalising a sister station that had never been switched on. Chernobyl in 1986 removed what was left of the argument, and in August 1999 the ban was raised to constitutional law — a nuclear-free Austria written in at the level where an ordinary parliamentary majority cannot reach it.

What made a no affordable

A country does not reject a power source on principle alone. It rejects it when it already has another one, and Austria's was poured in concrete long before the vote. Depending on the year's rainfall, hydro supplies somewhere between about half and two-thirds of everything the country generates, from several thousand plants ranging from village weirs to the high reservoirs above Kaprun.

Zwentendorf is remembered as a moral decision. It was a moral decision standing on forty years of Alpine concrete, and it would have been a far harder vote without them.

Kaprun is worth knowing about before admiring the result. Work on the high-mountain scheme began in 1938 under the German administration, using forced labour and prisoners of war; it stopped, restarted after the war with Marshall Plan money, and was completed in 1955. Men died building it. Post-war Austria then sold the finished dams to itself as a founding achievement of the Second Republic, which they were, and quietly declined to dwell on who had started them.

Fighting other people's reactors

The ban stops reactors on Austrian soil. It does not stop electrons. Austria was a net importer of electricity every year from 2010 to 2023; the grid operator booked a monthly export surplus in January 2024 for the first time since 2003, and the year closed 4,747 GWh in credit — then 2025 went straight back to importing. The European grid it draws on either way is heavily nuclear. Temelín, in Czechia, is roughly sixty kilometres from the border. In 2000 and 2001 Austrian activists blockaded border crossings over it, and the row was settled at Melk on 12 December 2000, in the abbey town on this route, when Austria agreed not to obstruct Czech accession to the EU in exchange for a safety process. A follow-up agreement was signed in Brussels a year later.

The pattern since has been consistent and unsuccessful. Austria challenged the Commission's approval of British state aid for Hinkley Point C and lost at the General Court in July 2018 and on appeal in 2020. It sued to have nuclear power removed from the EU's green investment taxonomy and lost that too, in September 2025, then appealed in November. This is expensive litigation with a poor record, and the government keeps bringing it because a constitutional article makes opposition to nuclear power a domestic obligation rather than a policy preference.

Going in

EVN, the Lower Austrian utility, has owned the site since 2005. There is a solar array on it now, and the buildings earn their keep as a training plant: technicians from countries that do operate reactors come to Zwentendorf to practise maintenance and dismantling on real components of a real boiling water reactor, in the one place on earth where getting it wrong contaminates nothing. Free guided tours have run since 2010, they book out, and they take you into the reactor building. Tulln is an hour from Vienna on the Krems line and the plant is ten kilometres beyond it — an easy morning, and a stranger one than any museum in the capital.