Finland is preparing to operationalise the world’s first permanent nuclear waste repository.
The facility, called Onkalo, is located on Olkiluoto Island.
Itwill store spent nuclear fuel for up to 100,000 years.
It is built 400–450 metres underground in stable bedrock using a multi-barrier safety system (metal canisters, copper capsules, bentonite clay, rock layers).
Bentonite clay swells on contact with water and prevents leakage of radioactive material.
The repository is designed for passive safety, meaning it will remain secure without human maintenance.
Finland plans to store about 6,500 tonnes of nuclear waste, providing a model for safe long-term disposal globally.