In about two to three years, nuclear waste will no longer be disposed on-site at the Olkiluoto nuclear power plant in Eurajoki. Instead, it will be buried 455 metres deep in an underground cave-like facility in Onkalo.
The site will allow spent nuclear fuel rods to be stored safely for millennia after being encased in boron steel canisters and then into a copper capsule. The encased canisters will then be placed underground in excavated caverns, which will then be backfilled with clay. This method is expected to contain radiation exposure for tens of thousands of years.
The facility in Onkalo, on the west coast, is the first of its kind in the world to safely dispose of nuclear waste permanently. Currently, it is standard practice in the industry for spent nuclear fuel to be stored on-site near reactors. A final licence for waste disposal at Onkalo is expected to be issued in 2024.
According to Gareth Law, a radiochemistry professor at the University of Helsinki, the eyes of the world are on this project.
"It's wonderful pragmatism," Law said, describing Finland's decisions on nuclear waste.
International disarray
In Finland, decision-making about the final disposal site has progressed more smoothly than in other countries. Apart from Finland, waste disposal locations have only been finalised in Sweden, Switzerland and France.
Law, originally from the UK, pointed to how a similar project fell through in his home country, where the borough of Copeland was willing to host a nuclear waste site, but its county government opposed.
"[The county of] Cumbria was afraid that radioactive waste would drive tourists away. The geology of the area also raised concerns," said Law.
In many countries, the topic of how to deal with nuclear waste brings up strong emotions, Law noted, further adding that Finland's low population density is more favourable than many other countries, as it is the least densely populated country in the EU.
Other countries have also faced obstacles in selecting the location of nuclear waste sites — this past summer Switzerland caused fear across the German border when it excavated test tunnels, and the Yucca Mountain nuclear waste repository in the US has been on hold since the 1980s.
"Decision-making is often very, very sticky when it comes to burying nuclear waste in bedrock," Law pointed out.
Smooth sailing in Finland
While Finland has struggled with building nuclear power plants like the long-delayed Olkiluoto 3, the construction of the Onkalo site has gone smoothly.
The excavation site was selected in 2000 and parliament approved it shortly after. By 2004, the firm Posiva began digging out the Onkalo facility.
In comparison, Sweden was prepared to create a permanent spent nuclear fuel depository in the 1990s and was supposedly 'ten years ahead' of Finland.
"Now Finland is ten years ahead of Sweden," Jessica Palmqvist, CEO of the Swedish nuclear waste disposal company SKB said in a video call with Yle.
However, Sweden has since chosen a final waste disposal site in Forsmark. In January 2022, the government approved the construction of the facility, but excavation work has yet to start. The firm SKB is waiting for an environmental permit and approval from Sweden's nuclear authorities.
"It is difficult to say anything for sure. But I believe the construction of the tunnels will start in the late 2020s and final waste disposal will be in the mid-2030s," Palmqvist said.
Some concern over canisters
Peter Szakalos, a corrosion researcher at the KTH Royal Institute of Technology in Sweden, said that corrosion and pressure can cause copper capsules to crack much more quickly than modelled, possibly within the span of up to a 1,000 years.
The Finnish and Swedish radiation safety authorities do not consider the corrosion threat to be significant.
Other countries are even further away from Finland and Sweden in terms of a final site.
"In the UK, for example, they are still looking for a site," Neil Hyatt, director of research at the NWS nuclear waste facility in the UK, told Yle.
Hyatt last visited the Onkalo site a year ago and was impressed by what he saw.
"It was inspiring to see how close Onkalo is to deployment. When final waste disposal actually starts somewhere, the whole spirit of the game changes," Hyatt said.
