Onkalo is the world's first facility for permanently disposing radioactive spent nuclear fuel. It is expected to operate until the 2120s.
After decades of construction, the world's first facility for permanently disposing of spent nuclear fuel is set to begin operations in Finland, with authorities expected to grant a license within months.
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The structure will become a final resting place for tons of dangerous radioactive waste.
The building of Onkalo, which means “cave” in Finnish, began on the west coast in 2004. The €1 billion facility is expected to operate until the 2120s.
'Isolated from civilisation'
The facility is located on the island of Olkiluoto, in a dense wooded area. The closest town is Eurajoki, about 15 kilometres away, which is home to roughly 9,000 people, many of whom work at the power plant or storage facility.
The site is near three of Finland’s five nuclear reactors. It was chosen for its bedrock, known for its high stability and low risk of earthquakes.
"The isolation from the civilisation and mankind on the surface is important because of the radiation caused by the waste," said Tuomas Pere, geologist at Posiva Oy, the company responsible for Finnish nuclear waste's management.
"But the thing is that by doing this final disposal, we can dispose of the waste more safely than by storing it in facilities located on the ground surface," he added.
Using unmanned machinery at a nearby encapsulation plant, radioactive rods will be sealed in copper canisters and then buried deep in tunnels over 400 metres underground, then packed in with “buffer” layers of water-absorbing bentonite clay.
Onkalo can store 6,500 tons of spent nuclear fuel, according to Posiva.
According to a 2022 report by the International Atomic Energy Agency, almost 400,000 tons of spent fuel have been produced since the 1950s, with two-thirds remaining in temporary storage and one-third being recycled in a complex process.
Currently, spent nuclear fuel is temporarily stored inside spent nuclear fuel pools at individual reactors and at dry cask storage sites above ground.
Remaining risks
But geologic disposal of nuclear waste is still fraught with “uncertainties”, warned Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, an American nonprofit organisation.
“My view of nuclear waste disposal is that there’s no good option, but it’s important to find the least bad option,” he said.
He said that permanently storing nuclear waste underground is better than leaving it on the surface, because the material could be vulnerable to sabotage when kept above ground.
The risks associated with nuclear waste repositories will mainly affect “future generations,” Lyman added.
Hence, nuclear semiotics is trying to develop warning signs about nuclear waste repositories that can be understood by humans 10,000 years from now - or much longer given that it takes hundreds of thousands of years before nuclear waste is no longer dangerous.
"We have had Chernobyl, we have had Fukushima and obviously the nuclear waste. We are perhaps somewhere close to a solution for that," Juha Aromaa, deputy programme manager at Greenpeace Finland, said, adding "nobody else in the world is anywhere near to solving this problem."
In 1994, legislation was passed requiring nuclear waste generated in Finland to be handled, stored and permanently disposed of within the country’s borders.
“Back then… some of the waste was still exported, but we wanted to take care of it ourselves,” said Sari Multala, Finland's environment minister.
Multala did not rule out eventually accepting limited amounts of nuclear waste from other countries.
