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Tunnel in Finland's Onkalo repository for spent radioactive fuel.

European Union nations grapple with nuclear waste storage

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The contrasting outcomes of countries’ efforts demonstrate the complexities in planning and developing permanent repositories for spent fuel and other radioactive material.

An excavated area of Finland's Onkalo nuclear waste repository.
The underground Onkalo repository in Finland is designed to safely and permanently store hazardous radioactive waste. Credit: Posiva

Finland and the former Yugoslavia adopted nuclear energy only four years apart. In 1971 Finland began construction of its first nuclear plant, Loviisa, and the first of two planned reactors went into commercial operation in 1977. Yugoslavia started building the Krško plant in 1975. In the 1980s, both countries acknowledged the need for a long-term nuclear waste management strategy and started making plans for permanent disposal repositories.

Fast-forward four decades, and Finland is on the verge of becoming the world’s first country to achieve permanent deep geological disposal for spent nuclear fuel, the highly radioactive waste that contains uranium, plutonium, fission products, and other heavy elements. Meanwhile, the fate of the spent fuel generated at Krško, which is jointly owned by former Yugoslavian republics Croatia and Slovenia, is still very much unknown. Both countries have yet to get a handle on even low-level radioactive waste, including contaminated clothes and water filters, which is slowly overwhelming storage facilities and threatening to halt plant operation.

The US has long struggled to find a final resting place for its nuclear waste, to the point that it is now spending billions of dollars to reimburse plant operators for the costs of storing spent fuel. The dramatically different outcomes of Finland and Croatia’s lengthy searches for permanent nuclear waste solutions are reflections of the varied ways in which this long-standing worldwide problem is being tackled by the nations of the European Union. Whereas Finland, Sweden, and France are expected to open permanent underground spent-fuel repositories by the early 2030s, 12 other nuclear EU countries are far behind, planning to open deep geological disposal facilities sometime between the 2040s and the 2100s. According to a 2019 European Commission report on the implementation of its nuclear waste directive, only a few of those nations have made progress in selecting a site.

Finland and the need for buy-in

In 2001 the Finnish parliament approved a site on the west coast of the country and construction of the repository and encapsulation plant. Named Onkalo, the facility began as an underground research laboratory (see the article by Vincent Ialenti, Physics Today, October 2017, page 48). In 2015 Posiva, the company established by Finnish nuclear plant owners to handle the waste, extended the facility to a depth of 455 meters. Today Onkalo has four vertical shafts for personnel, canisters, and ventilation. Plans call for up to 35 kilometers of tunnels to be excavated in the future.

Once in full operation, Onkalo will be able to receive the 6500 metric tons of spent fuel predicted to accumulate from all five nuclear power plant units in Finland. The disposal facility is expected to be used for about a century and then closed off. The Finns left open the possibility of retrieving the spent fuel from the sealed repository if a use for the waste is found in the future.

Sweden: An emphasis on safety

Sweden has been generating electricity with nuclear energy since the 1960s. The country’s scientists also pioneered nuclear waste technology that is used today by other nations. Notably, the main safety feature of Finland’s Onkalo repository is a multibarrier radioactive leak shield that is based on a Swedish design.

Despite Sweden’s important role in nuclear technology, strict licensing procedures delayed its quest to build a permanent waste depository. In 2009 the country chose separate locations for an encapsulation plant and a deep geological repository. SKB, the equivalent of Finland’s Posiva, is awaiting a construction license from the Land and Environment Court and the Swedish Radiation Safety Authority.

Nothing is taken for granted in Sweden. For instance, SKB had to relocate frogs and crested newts from ponds on the future construction site. New facilities for the animals include ponds and a “frog hotel” where the amphibians can spend the winter.

Posiva applied for an operating license at the end of 2021 and hopes to receive the green light to open the repository by the beginning of next year. “It was never the idea of ‘Let’s create some temporary solution, and then somebody else will think of something better after 40 years,’ ” says Pasi Tuohimaa, Posiva’s head of communication.

The reasons for the differing outcomes in tackling nuclear waste are complex, and they apparently depend on more than countries’ relative economic strength and geological features. “While geology varies between countries, it is possible to find suitable sites from a geology perspective. So the reasons why the development of disposal has been difficult lie somewhere else,” says Jussi Heinonen, director of nuclear waste management at Finland’s Radiation and Nuclear Safety Authority and member of an international team of specialists on the subject gathered by the International Atomic Energy Agency. “I would say that they are mostly related to levels of political will and the shortage of public support.”

Though it was a lengthy process, site selection in Finland apparently went without big delays. “In Finland we had the political will to have a permanent solution for radioactive waste and a schedule set by the government,” says Heinonen. “And we had the courage to make decisions so that project had the possibility to progress.” For any suggested location, the acceptance of the local government was mandatory. Two municipalities that host nuclear plants ended up competing for the repository.

The challenge of winning public acceptance of potential storage sites has been downplayed by more than a few EU governments. In Germany, for example, the municipality of Gorleben was named back in the 1970s as the site for a spent-fuel repository in a purely political decision. Years of public protests eventually terminated the plan. The site-selection process was reestablished only in 2017, and the federal company responsible for nuclear waste disposal now says a new site will not be named before 2046. Germany shut down its three remaining nuclear power plant reactors in April.

Diagram of Onkalo's underground infrastructure.
A schematic of Onkalo. Credit: Posiva

The drawn-out timetable has prompted worries at the German Federal Office for the Safety of Nuclear Waste Management (BASE) that citizens could lose interest in the process. Municipalities will not have the final word about the site choice, but this time the plan is for the public to be highly involved. “The process should be scientifically proven and understandable to the public,” says Christoph Hamann, head of communication at BASE. “It’s not about injecting the money into that area and silencing people.”

Indecision in Croatia

For some countries, disposing of even the less dangerous types of waste has proved to be challenging. In that sense, the case of Croatia provides a sharp contrast to the success story of Finland. Although war in the early 1990s disrupted Croatia’s search for a repository location, a recent investigation by this author showed that wasn’t the main reason for the country’s current struggles to manage its radioactive waste.

Records from the 1990s show that within a few years of the war’s end, more than 80 experts from 15 institutions had identified four equally suitable potential locations for a near-surface permanent repository for low- and intermediate-level radioactive waste. But in 1997 a group of Croatian members of parliament quickly rejected two of the selections. Two years later, a third location was dismissed in a similar manner. That left Trgovska gora, located five kilometers from Croatia’s border with Bosnia and Herzegovina, as the only remaining area.

At the beginning of the millennium, Croatia and Slovenia signed an agreement for each country to accept half of the low-level waste accumulated in Krško by 2023, when storage at the plant was expected to reach full capacity. Despite that looming deadline, the planning process in Croatia dramatically slowed down. In 2016, pushed by a warning from the European Commission, the government proposed a national plan in which the future waste facility was defined only as temporary storage. The former military compound Čerkezovac at Trgovska gora was named the “preferred facility site.” A clear scientific explanation of how the specific location was chosen is nowhere to be found in official documents, even though a European Atomic Energy Community directive states that the public should be informed about the decision-making process.

Krško Nuclear Power Plant.
The Krško Nuclear Power Plant has been operating along the Sava River in what is now Slovenia since 1983. Credit: NEK

Croatia began conducting more detailed field studies around Čerkezovac last year, but time is running short. Today neither Croatia nor Slovenia is ready to accept waste from the plant, although Slovenia is expected to start construction on a permanent repository this year.

Krško will likely have to squeeze in more low- and intermediate-level waste for the next few years as well as melt some of the waste in a third country. Spent fuel will remain stored at the plant site for years to come. There is sufficient dry storage on-site, and it is licensed for a 100-year period, says Saša Medaković, a member of the Krško management board. “In the meantime, Slovenia and Croatia will have to find a permanent solution.”

An uncertain future

The divergent paths of Finland and Croatia illustrate only some of the factors involved in addressing radioactive waste storage at the national level. Crucially, Finland managed to nail the big issue of money, something that is still bothering many other EU nuclear members: After a decades-long site-selection process, will there be enough left for the actual construction of permanent repositories? By having owners of nuclear plants pay a percentage of profits to a waste fund run by the government, Finland has collected €2.5 billion (about $2.7 billion). So far, says Tuohimaa, the country has spent a little less than €1 billion on the repository. The facility will cost around €40 million per year to operate.

Krško Nuclear Power Plant spent fuel pit.
A pool stores spent fuel at the Krško power plant in Slovenia. Credit: NEK

Although the cost of nuclear waste management is usually less than 10% of the profit from electricity production, repositories on the scale of billions of euros could be unaffordable for countries with smaller nuclear waste inventories. And although some nations are considering sharing disposal facilities, so far nothing has come of the idea. Croatia, for example, failed to come to an agreement with Slovenia four years ago for the latter country to accept both nations’ waste from Krško. “When it is difficult to have political and public support for disposal of national waste, acceptance of waste from other countries seems to bring another level of difficulty in discussion,” Heinonen says.

Considering the complications, it is likely that a large portion of the EU’s high-level nuclear waste—as well as that of the US and other nuclear nations around the world—will become a burden for future generations. Many countries will not have permanent repositories in the first half of the century, and some potentially not in this century at all. The challenge now, as the European Commission stated in its 2019 report, is to ensure the long-term safety of existing storage facilities for many decades to come.

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