The nuclear waste repository in Finland designed to outlast modern civilisation

New Scientist · George Bass, Jacklin Kwan · 2026-11-03 16:00 UTC

The first engineered structure built to last for 100,000 years is about to begin operations. The hope is that Onkalo, deep below ground in Finland, will offer a safe place for the country to store nuclear waste

An emergency lift at the Onkalo repository in Finland, where nuclear waste will be stored indefinitely

There’s a timeless quality to the tunnels at Onkalo. And that’s the point. Carved into the rock more than 400 metres below ground, these passageways are part of a facility built for the long term. The extreme long term.

In fact, facilities such as Onkalo “should exist intact for at least 100,000, if not a million years”, says Allison Macfarlane at the University of British Columbia in Canada, who previously served as chair of the Nuclear Regulatory Commission in the US. “Those are geologic timescales.”

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