Finland Pioneers Permanent Nuclear Waste Disposal Solutions

Since the inception of nuclear energy in the 1950s, over 400 reactors across 31 nations have generated approximately 430,000 metric tons of spent nuclear fuel. Despite this significant development, a permanent disposal solution for this waste has remained elusive. According to the International Atomic Energy Agency, around 30% of this spent fuel has been reprocessed, allowing for the recycling of elements to create new nuclear fuel. However, the remaining 70% is currently stored in temporary facilities, awaiting a definitive disposal method.

As the nuclear sector experiences a revival--driven by the global push for decarbonized energy and the burgeoning demand for electricity from technology, particularly AI--the urgency for effective nuclear waste management intensifies. The most viable approach involves entombing spent fuel in an underground repository capable of safely containing it for thousands of years. The threat posed by spent nuclear fuel to human health persists for at least 10,000 years, with some materials remaining radioactive for millions of years. While several nations are exploring this route, none have made as much progress as Finland, which is advancing towards the establishment of a permanent disposal site.

Located on Finland's western coast, about three hours from Helsinki, the Onkalo facility is designated to serve as the nation's first encapsulation plant. This facility will manage spent fuel from Finland's five operational nuclear reactors--three situated on the island of Olkiluoto and two in Loviisa, southeastern Finland. The repository is being developed by Posiva Oy, a Finnish company founded in 1995 by two nuclear operators to create a long-term storage solution.

At a depth of 430 meters within the bedrock, testing is currently in progress. The process involves encasing spent fuel rods in copper canisters, which are then placed into slots carved into the granite walls of the underground repository. The entire assembly is sealed with bentonite, a soft clay that insulates the containers while providing a buffer against any minor geological movements.

In mid-March, five test canisters filled with nonradioactive materials were sealed at an aboveground facility, then transported underground to be stored along a 70-meter tunnel, demonstrating an initial proof of concept for Onkalo's storage methodology. This successful trial positions Finland as a frontrunner in the quest to establish the world's first operational deep geological repository.

To date, the construction of Onkalo has incurred costs of approximately EUR900 million, with an additional EUR4 billion projected to complete the project. The development process has involved extensive research to identify the optimal site and years of navigating regulatory approvals. Despite the progress, some skepticism remains among locals regarding the project, reflecting concerns over the safety of nuclear waste storage in their vicinity and the perceived ease with which Posiva Oy secured the necessary permits. Additionally, experts have raised alarm over potential corrosion of the storage containers, particularly the copper canisters.

In January 2023, a study led by Jinshan Pan, a corrosion science professor at KTH Royal Institute of Technology in Sweden, highlighted the risks posed by sulfides in groundwater potentially corroding the copper canisters used for storing spent nuclear fuel. The study emphasizes the need for further research to comprehend the materials' behavior under repository conditions.

While Finland appears poised to lead in this domain, other nations are also progressing with their own nuclear waste disposal plans. Sweden, for instance, is gearing up to initiate work on a repository designed to accommodate up to 12,000 metric tons of spent nuclear fuel, projected to consist of 60 kilometers of tunnels extending 500 meters underground. This project has been in planning for four decades and recently obtained the necessary environmental permits. However, construction could face delays due to appeals from environmental groups.

In North America, Canada is on track to develop a storage facility after extensive discussions and community engagement led to the selection of a site in Ignace, Ontario, which has garnered support from local indigenous communities. Meanwhile, France and Switzerland are also advancing their repository projects, albeit facing bureaucratic challenges. France's Cigéo project may begin fieldwork as early as 2027, while Switzerland is nearing final approval for its repository, anticipated to operate by 2060.

Italy is in the process of evaluating 51 potential sites for a nuclear waste repository, with plans initially outlined in 2015. The government has reopened applications to consider new proposals, as existing radioactive materials remain in temporary storage at various decommissioned nuclear facilities.