Finland’s world-first nuclear waste repository is built to last 100,000 years

Finland is close to approving Onkalo, a deep geological repository for spent nuclear fuel near Olkiluoto.

The nuclear regulator STUK is expected to issue its final safety assessment by the end of June, a key step toward an operating license.

Built 430 meters underground, Onkalo is designed to store up to 6,500 tonnes of spent fuel in copper canisters, bentonite clay, and sealed tunnels.

If approved, it would become the world’s first operating permanent repository for nuclear waste and a global precedent for long-term disposal.