Finland Grants Licence for Onkalo, Planned Underground Nuclear Waste Repository
Finland's government has granted an operating licence for Onkalo, a site in western Finland that is described as the world's first permanent underground repository for spent nuclear fuel. According to Posiva, the government granted the licence to Posiva, the waste management company that runs the project, on 22 October 2026.
Spent nuclear fuel is fuel that has been used up in a reactor and taken out of it. It remains radioactive, which is why it needs long-term isolation from people and the environment. Onkalo, a Finnish word meaning "cave", is located on Olkiluoto island and sits at a depth of 400 to 430 metres, according to Posiva. It has space for 6,500 tonnes of uranium and will hold spent fuel from Finland's five nuclear reactors.
The method is designed to keep the fuel sealed in place. Al Jazeera reported that the fuel will be enclosed in corrosion-resistant copper canisters, lowered into holes in the bedrock, and surrounded by bentonite clay. Each hole is then sealed with a steel-reinforced concrete plug. The bedrock that will host the repository is 1.9 billion years old, according to PBS.
An operating licence does not by itself allow the site to open. Posiva will first complete commissioning, the stage in which the systems are installed and tested, and the tests and inspections must be verified and approved by STUK, the Finnish Radiation and Nuclear Safety Authority, before final disposal begins. Al Jazeera reported that operations are expected to start soon, but that no exact opening date had been decided as of 23 October 2026.
The project has a long history. Posiva records June 2004 as the start date for the repository work at Onkalo, and Al Jazeera reported that construction began 22 years before October 2026. On 4 August 2026, Posiva announced that a STUK safety assessment had brought the facility closer to an operating licence. The Finnish Government decides on the licence on its own schedule, according to STUK. Posiva has estimated the cost of the Onkalo site at $1.16 billion, and its chief executive is Ilkka Poikolainen.
