Finland Could Be the First Country in the World to Bury Nuclear Waste Permanently

Since the arrival of nuclear power in the 1950s, more than 400 reactors in 31 countries have produced about 430,000 metric tons of spent nuclear fuel, and until now no one has developed a permanent solution for disposing of it. The International Atomic Energy Agency estimates that about 30 percent of this fuel has been reprocessed—elements in spent fuel can be recycled to create new fuel for nuclear plants—but the rest has been “parked” in temporary storage systems, with its final destination yet to be determined.

And with the nuclear sector showing signs of undergoing a renaissance—as countries look to decarbonize energy production and with the tech sector seeking ways to power its electricity-hungry AI systems—the pressure for nuclear-waste disposal is likely to grow.

The best solution would be to put spent fuel in an underground facility that can contain it safely for millennia. Spent fuel is a major threat to human health for at least 10,000 years and remains radioactive for several million. But such facilities have to be built from scratch, and while several are being developed, none have been completed. The leader in this race is Finland, which has dug the underground space needed for a repository.

On the country’s west coast, roughly three hours’ drive from the capital, Helsinki, is what will become the country’s first encapsulation plant. Known as Onkalo, it will receive spent fuel from Finland’s five nuclear reactors—three on the nearby island of Olkiluoto and two in Loviisa, in the southeast of the country. The repository is being built by Posiva Oy, a Finnish company set up by two of the country’s nuclear operators in 1995 to find a way of permanently storing spent nuclear fuel.

In the bedrock here, at a depth of 430 meters, testing is underway. Storage of spent fuel involves placing spent fuel rods inside copper canisters, which in turn have to be inserted into slots dug into the granite walls of the subterranean repository. Everything is then sealed with bentonite, a soft, plastic clay that insulates the containers and acts as a buffer against minor movements in the bedrock.

In mid-March, five test containers, filled with nonradioactive materials, were sealed in a special aboveground facility before being transported underground and stored along a 70-meter-long subterranean tunnel, to provide an initial proof of concept for Onkalo’s storage process. The completion of this dummy run puts Finland in the lead in the race to build the world’s first operational deep geological repository.

Onkalo’s construction has so far cost €900 million, while an estimated €4 billion more is needed to complete the project. Breaking ground here followed decades of research to find the best location for the repository and years waiting for permits and approvals. There are some who still don’t believe the project will happen and others who hope it won’t. Some locals have been hostile to the project, unhappy with the prospect of nuclear waste being stored nearby and perplexed at how easily, in their opinion, Posiva Oy was able to get permits for the repository. Researchers have also expressed concerns about potential corrosion of storage containers, specifically the copper canisters.

Together with his colleagues, Jinshan Pan, a professor of corrosion science at KTH Royal Institute of Technology in Sweden, published a study in January 2023 devoted to the risk of sulfides in groundwater corroding the copper used for spent nuclear fuel containers. “More work is needed to define […] the nature and chemistry of the surface films that develop on copper surfaces in repository conditions,” the paper says.

While Posiva Oy looks like it may have the first functioning repository, other countries are following its lead. Neighbouring Sweden is also preparing to start work on its own repository, which is intended to contain up to 12,000 metric tons of Swedish spent nuclear fuel. It is expected to extend over 60 kilometers of tunnel once it is finished, at a depth of 500 meters. It is a major work that has been on the drawing table for 40 years and obtained its necessary environmental permits for construction only a few months ago. Construction could start within the next decade and would continue until the 2080s, with this repository’s underground space gradually extending—provided an appeal made by the Office for Nuclear Waste Review, a Swedish NGO, does not slow or halt the work. Concerns about the Swedish project are the same as with the Finnish one: danger of corrosion of the copper canisters, possibly resulting in the release of radioactive elements into the groundwater.

On the other side of the Atlantic, Canada is also planning to build a storage facility. The repository doesn’t exist yet, but the path forward appears relatively free of obstacles—at least there are no apparent legal ones. After 14 years of dialog and debates, the relevant bodies and citizens have selected a host site within the Township of Ignace, Ontario, part of the indigenous community the Wabigoon Lake Ojibway Nation. Both the town and nation were open to the project, seeing it as a source of investments and new jobs.

France and Switzerland are also working on projects, gradually making progress, even if much of it is a matter of getting over bureaucratic hurdles. In the Meuse region of northeastern France, field work on the Cigéo project could begin in 2027 now that it has received a positive assessment of its soundness. The implementing company Andra has been authorized to continue with plans, providing it gives greater consideration to the potential impact of climate change on the aboveground structures.

It has taken Switzerland’s national radioactive-waste-disposal cooperative, Nagra, 14 years to decide where to locate its storage facility. It has chosen to build its repository north of Zurich, in Nördlich Lägern, because it is an area particularly rich in very compact opaline clay, which is perfect for acting as a long-term container for radioactive materials. (Finland’s site is also rich in this material.) Final approval is expected around 2030, subject to a referendum, and the repository should start to operate by 2060.

Finally, Italy is considering 51 sites that could potentially be suitable to host a repository for nuclear waste storage. These plans were first drawn up in 2015 and then published in December 2023. The government has since decided to reopen the application process to accommodate new applications. In the meantime, radioactive waste in the country remains stored in temporary repositories at the sites of decommissioned nuclear power plants, nuclear research facilities, and nuclear medicine and industry locations.

This story originally appeared on WIRED Italia and has been translated from Italian.