In 1954, Sweden's first nuclear reactor reached criticality – in a rock cavern in Stockholm. A comparison of Sweden’s Reactor 1 – then and now – demonstrates the potential for innovative reuse after a heavy industrial asset has been shut down.

For nearly 65 years, most passers-by at the Royal Institute of Technology (KTH) in Stockholm, Sweden have been unaware of the work of creative minds in a rock cavern below. But behind an inconspicuous entrance, just steps from the city’s bustling East Station, an elevator brings you 25m down into the bedrock where a unique site – and sight – awaits. While there are obvious differences between now and when the reactor was in operation, the overarching objectives are strikingly similar: experimentation, collaboration, learning and sharing.

The dawn of nuclear

Excavations of the R1 reactor hall began in July 1951, and three years later, the reactor was in use. Initially it operated at 100 kW, but over time thermal power was increased to 1MW. Given the shape of the hall and the prevailing view of nuclear as the future, R1 became the “Cathedral of Science and Technology.”

Karl-Erik Jonsson, a radiation protection technologist at R1 from 1959 to 1962, recalls: “Those were very different times. There were no limits. Whenever we asked for money for something, we got it.”

Irradiation experiments were conducted using both a central channel into the reactor core and neutron beam ports on the sides. Karl-Erik Jonsson explains: “It was all about learning at that time. So all kinds of things were placed in the central channel, including grains and fruit tree seedlings.”

The second act

After more than a decade of being mothballed, a few faculty members had an idea: reuse the hall as an experimental performance space where scientists and artists can collaborate. That was the beginning of what has become a venue for a wide range of activities, such as art installations, film productions, and live theatre and concerts. This includes being the set of music videos such as Madonna’s “Nothing really matters” and Alan Walker’s “Faded (Restrung).”

When exiting the elevator and entering the reactor hall it is easy to see why. A clearly industrial scene – with railings, pipes, overhead crane, offices and control room equipment still in place – but with a sky-like ceiling. Old mechanical designs, mixed with the latest multimedia technology. Everywhere, the spray-painted grid used to confirm that the site was below release limits. And in the middle, a gaping hole where the reactor used to be.

Research is also a cornerstone of the revived activities at R1, including visually connecting remote places to enable high-quality long-distance communication. Leif Handberg, associate professor in Media Technology at KTH, has been instrumental in the R1 revival and explains: “Both science and arts are embedded in KTH’s logo. So through R1, we enable these to be integrated. We strive to showcase to the rest of society the innovative work of today’s bright minds.”

“If they had known what R1 would become, more could have been kept and reused," says Leif Handberg. Even so, it is clear that the site of Sweden’s only fully decommissioned reactor has found a new productive use and continues to both aspire and inspire.

This article is a summary of “Sweden’s Reactor 1 – then and now,” by Lloyd's Register's Kristina Gillin for the December 2018 issue of Nuclear Engineering International. You can access the full version here, Page 42 to 43

Spiral staircase inside Sweden's R1 reactor hall.

The rows of offices inside the R1 reactor hall were not demolished during decommissioning. Photo: Maria Fardi