Onkalo will be the first spent nuclear fuel storage facility in the world. At a depth of more than 400 meters, the Onkalo reservoir is designed to hold a total of 6,500 tons of uranium.
The used uranium will be contained in thick copper capsules and buried in the rock. The project will move into the operational phase in the mid-2020s, says Johanna Hansen, research and development coordinator at onkalo. The company insists the capsules are designed to withstand noticeable changes.