Deep in the Finnish rocks, the headlights of heavy machinery cast shadows into eerie, glittering tunnels of waterdrops in a graveyard that will soon become a potentially perilous graveyard.
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“Onkalo will be the world’s first spent nuclear fuel storage facility,” geologist Johanna Hansen, research and development coordinator at Onkalo, told AFP.
On the green island of Olkiluoto in the Gulf of Bothnia off the west coast of Finland – where Europe’s largest nuclear reactor already stands – the project to solve the thorny mystery of the fate of nuclear waste is coming to an end.
More than 400 meters deep, the Onkalo repository is expected to house a total of 6,500 tons of uranium, enough to cover the amount of spent fuel from Finland’s five nuclear reactors during their lifetime.
Low-carbon nuclear energy represents a useful source of clean energy to help mitigate global warming.
According to estimates by the World Nuclear Association, around 400,000 tons of spent fuel have been removed from the reactors, most of them stored in interim storage facilities.
Photo Jonathan NACKSTRAND / AFP
Long-term storage puts a strain on nuclear projects around the world.
Under the solution that Posiva, the operator of Onkalo, has chosen together with the Swedish authorities, the spent uranium is sealed in thick copper casings and buried in the rock before the tunnel is sealed with a huge plug, a reinforced steel wedge.
Work at Onkalo (“hollow” in Finnish) started in 2004 and the final tests will take place in early 2024.
“Once we are confident that we are ready, we can move to the operational phase in the mid-2020s,” says Hansen.
Photo Jonathan NACKSTRAND / AFP
permanent radiation
The significant delays – around 250,000 years for the most toxic waste – required for radiation to drop to safe levels pose daunting challenges.
For comparison: Europe was in an ice age 250,000 years ago and was inhabited by Neanderthals and mammoths, while Homo sapiens had just appeared in Africa.
Therefore, before the radiation from the waste returns to the levels of uranium in its natural state, the appearance of Olkiluoto Island may have changed drastically.
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In the next few millennia, Olkiluoto could become part of the continent as the Finnish coast expands. Or, according to Posiva, being submerged due to sea level rise due to climate change.
However, the operator emphasizes that the housings are designed in such a way that they can withstand significant changes.
However, some experts remain skeptical.
Photo Jonathan NACKSTRAND / AFP
Researchers at the Swedish Polytechnic (KTH) regularly questioned the safety of the device, citing the risk of copper corrosion that could lead to a leak.
“It’s not a solution, it’s risk reduction,” Jan Haverkamp, nuclear specialist at environmental NGO Greenpeace, told AFP.
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According to him, Posiva “doesn’t pay any real attention” to the issue of copper rust.
Fears were eliminated by the project managers. For the Finnish Nuclear Safety Authority, Onkalo meets the requirements.
According to Allison Macfarlane, a professor at the University of British Columbia, no project is “100% secure,” but Onkalo is “certainly the solution that has been researched most thoroughly.”
Photo Jonathan NACKSTRAND / AFP
The alternative, she says, would be to “leave the waste at the surface indefinitely,” a much riskier assumption.
At carefully chosen sites, the waste will remain safe for “thousands and tens of thousands of years,” she says. “I don’t think there’s much point in thinking beyond that.”
Photo Jonathan NACKSTRAND / AFP
More projects in progress
Other potential landfill sites were selected in Sweden, France and Switzerland. A decision is also expected shortly in Canada.
“It’s the globally accepted solution to the nuclear waste problem,” Macfarlane said.
But many projects are met with resistance, such as Cigéo in Bure in eastern France.
According to Ms. Hansen, however, the tide has turned in Finland.
Photo Jonathan NACKSTRAND / AFP
In April, the new generation Olkiluoto 3 nuclear reactor, the most powerful in Europe, went into production.
In the same month, a poll released by the Finnish Energy trade association found support for nuclear power in the country to be a record 68%.
“Sweden and Finland have shown that technical challenges can be overcome,” says Macfarlane.
“The remaining challenges are political in nature.”