The Nuclear Waste Management Organization (NWMO) is congratulating the Finnish spent nuclear fuel final disposal company Posiva on a major milestone in constructing a deep geological repository for used nuclear fuel.

The project is located about 260 kilometres northwest of Helsinki, Finland, at Olkiluoto island at the country’s western coast. In May 2021, it reached a significant milestone, when the excavation of the first actual final deposition tunnels started at the depth of 420 metres in the ONKALO repository that will eventually house used nuclear fuel from utilities owning Posiva. Work on these tunnels means that Finland is poised to be the first country with an operating repository for used nuclear fuel. Final disposal is scheduled to start in mid 2020s.

“It is really exciting to see the work coming to life. While Finland is leading the way, the NWMO is working equally hard to implement Canada’s long-term plan. A deep geological repository is the international best practice and scientifically accepted solution for safely containing and isolating used nuclear fuel for the very long term,” said Chris Boyle, NWMO Chief Engineer. “Our working relationship with Posiva in Finland is one of many we have with countries around the world pursuing very similar solutions to storing their used nuclear fuel. With site selection just two years away, Canada and the NWMO are excited to learn from and build on the progress being made in Finland by Posiva,” Mr. Boyle said.

There are repositories for low- and intermediate-level radioactive waste operating safely in a number of other countries right now, including Sweden, Finland, South Korea, and the United States, but the ONKALO repository would be the first to hold used nuclear fuel, high-level radioactive waste.

“Posiva is constructing the encapsulation plant and the final disposal facility underground and preparing to submit the application for operating licence to the authorities – first in the world. These are exciting times indeed. We are also happy that our work has been useful for the NWMO,” says Ms. Tiina Jalonen, Development Director at Posiva.

The NWMO is responsible for the safe, long-term management of used nuclear fuel in Canada, and has co-operation agreements with our counterparts in Belgium, Finland, France, Japan, South Korea, Sweden, Switzerland, and the United Kingdom. The NWMO has worked closely for years with Posiva and waste management organizations in other countries to share knowledge and best practices. There are many similarities between the Finnish and Canadian plans: used nuclear fuel will be placed in the bedrock at a depth of about 500 metres depending on the geology at the site, the disposal container consists of a sealed iron-copper canister, and a bentonite clay buffer will enclose the canister.

Between 2018 and 2020, a team of NWMO technical specialists visited the Posiva site several times to learn from their progress and share best practices. The knowledge sharing has proved beneficial to both countries, especially given the NWMO’s emphasis on studying the placement and performance of both copper and bentonite clay in a deep geological repository.