The first nuclear waste cemetery makes its mark in Finland

Deep in Finnish rock, the headlights of heavy machinery cast shadows in eerie, glistening tunnels of water droplets in what will soon become a potentially high-risk graveyard.

“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 verdant island of Olkiluoto in the Gulf of Bothnia, off the west coast of Finland – already home to Europe’s largest nuclear reactor – the project meant to solve the thorny puzzle of fate nuclear waste is coming to an end.

More than 400 meters deep, the Onkalo repository is designed to house a total of 6,500 tonnes of uranium, enough to cover the amount of spent fuel from Finland’s five nuclear reactors over their lifetime.

Low in carbon, nuclear energy represents a useful source of clean energy to help contain global warming.

Some 400,000 tonnes of spent fuel have so far been extracted from the reactors, estimates the World Nuclear Association, most of it stored in temporary storage.

Long-term storage plagues nuclear projects around the world.

According to the solution adopted by Posiva, the operator of Onkalo, together with the Swedish authorities, the spent uranium will be enclosed in thick copper casings and buried in the rock, before the tunnel is sealed with a huge plug. reinforced steel wedge.

Work at Onkalo (“trough” in Finnish) started in 2004 and the final tests will take place in early 2024.

“Once we are sure we are ready, we can move into the operational phase in the mid-2020s,” says Hansen.

The considerable delays – some 250,000 years for the most toxic waste – required for radiation to fall to safe levels pose daunting challenges.

For comparison, Europe 250,000 years ago was in an ice age and occupied by Neanderthals and mammoths, with Homo sapiens having just emerged in Africa.

Before the level of radiation from the waste drops back to that of uranium in its natural state, the physiognomy of the island of Olkiluoto could therefore have changed drastically.

In the next millennia, Olkiluoto could become part of the continent as the Finnish coast extends. Or be submerged due to sea level rise due to climate change, according to Posiva.

But, insists the operator, the cases are designed to withstand considerable changes.

Some experts, however, remain skeptical.

Researchers from the Swedish Polytechnic School (KTH) have regularly questioned the safety of the device, citing the risk of copper corrosion which could lead to a leak.

“It’s not a solution, it’s risk reduction,” Jan Haverkamp, ??a nuclear expert with environmental NGO Greenpeace, told AFP.

According to him, Posiva pays “no real attention” to this subject of copper rust.

Fears swept away by the project leaders. For the Finnish Nuclear Safety Authority, Onkalo meets the requirements.

Professor at the University of British Columbia, Allison Macfarlane judges that no project is “100% sure” but that Onkalo is “certainly the solution that has been the most searched”.

The alternative, she says, would be to “leave the waste on 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 it makes much sense to project beyond that.”

Sites for other potential landfill facilities have been 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 come up against opposition, such as Cigéo in Bure in the east of France.

However, the tide has turned in Finland, according to Ms. Hansen.

In April, the new generation nuclear reactor Olkiluoto 3, the most powerful in Europe, went into production.

In the same month, a poll published by the trade association Finnish Energy highlighted record support for nuclear power in the country, with 68% in favor.

“Sweden and Finland have demonstrated that technical challenges can be overcome,” says Macfarlane.

“The remaining challenges are political in nature.”

06/06/2023 11:54:30 – Olkiluoto (Finland) (AFP) – © 2023 AFP