Finland grants license for the world's first permanent nuclear waste repository

Posiva's CEO, Ilkka Poikolainen, said in a statement, "This is a great and historic day for both Posiva and Finland."

The site, named "Onkalo"—a term meaning "cave" in Finnish—is expected to begin operations soon, but Posiva stated that an exact date has not yet been determined.

Before final disposal begins, the company will complete a trial operation phase by conducting necessary tests and inspections, which the Radiation and Nuclear Safety Authority of Finland must also verify and approve.

With a capacity of 6,500 tonnes of uranium, the Onkalo site will provide permanent storage for spent fuel from Finland's five nuclear reactors.

The fuel will be placed inside highly corrosion-resistant copper canisters, which will then be lowered into boreholes drilled into the bedrock tunnels. These holes will be filled with bentonite clay and ultimately sealed with steel-reinforced concrete.

The fuel will remain highly radioactive for tens of thousands of years. According to Posiva, after about 100,000 years, its radiation levels will become roughly similar to those of the uranium ore from which the fuel was made.

Countries have been working on finding solutions to handle hazardous nuclear byproducts since the establishment of the first plants in the 1950s. Currently, most of these materials are in temporary storage locations.

Final repositories are under construction in other countries, including neighboring Sweden and France, but Finland is expected to be the first country to open an underground storage facility.

The cost of the Onkalo site is estimated at $1.16 billion.