Finland nearing opening of world’s first permanent nuclear waste repository

The Finnish government has granted an operating licence for Onkalo, a site in western Finland, to the waste management company Posiva. This move, announced on Thursday, authorises the facility's operation but does not yet set an opening date. Construction began 22 years ago, and the company expects the site to start operations soon.

Onkalo, which means 'cave' in Finnish, is designed to provide permanent storage for spent nuclear fuel from Finland's five reactors. The site has space for 6,500 tonnes of uranium. The fuel will be enclosed in copper canisters, which are highly resistant to corrosion, and then lowered into holes drilled into the bedrock.

The repository will be filled with bentonite clay and sealed with a steel-reinforced concrete plug. The waste will remain highly radioactive for tens of thousands of years. After about 100,000 years, the radiation levels will drop to the same as the uranium ore of which the fuel is made, according to Posiva.

Posiva’s Chief Executive Officer Ilkka Poikolainen described the moment as a 'great and historic day for both Posiva and Finland.' The company will now proceed with the commissioning stage, carrying out necessary tests and inspections. The Finnish Radiation and Nuclear Safety Authority, STUK, will also verify and approve these steps before final disposal begins.

Countries have struggled with the disposal of nuclear by-products since the 1950s. Most of it is currently in temporary storage. Final repositories are being built in other countries, including neighbouring Sweden and France, but Finland is expected to be the first to open its underground storage facility. The cost of the Onkalo site has been estimated at $1.16bn.