Finland greenlights world's first permanent underground nuclear waste repository

Finland announced approval for Onkalo, the world’s inaugural permanent underground storage site for spent nuclear fuel, located in stable bedrock near Eurajoki in southwestern Finland. The repository, managed by Posiva, is designed to accommodate roughly 6,500 tons of uranium from Finland’s five nuclear power plants, with fuel sealed in corrosion-resistant copper canisters. These canisters will be placed in drilled holes, backfilled with bentonite clay, and capped with a steel-reinforced concrete plug.

Before any fuel is emplaced, Posiva must complete a commissioning stage that includes extensive testing and inspections, which must be. The facility is expected to begin operations soon, though no exact start date has been set. Once sealed, the waste will remain hazardous for tens of thousands of years, eventually decaying to levels comparable to natural uranium ore after about 100,000 years.