TheOnkalo spent nuclear fuel repository is adeep geological repository for the final disposal ofspent nuclear fuel.[1][2] It is near theOlkiluoto Nuclear Power Plant in the municipality ofEurajoki, on the west coast ofFinland. It will be the world's first long-term disposal facility for spent nuclear fuel.[a][3] It is being constructed byPosiva, and is based on theKBS-3 method of nuclear waste burial developed inSweden bySvensk Kärnbränslehantering AB (SKB). The facility will be operational by 2026, and decommissioned by 2100.[4][5][6]
After theFinnish Nuclear Energy Act[7] was amended in 1994 to specify that allnuclear waste produced in Finland must be disposed of in Finland, Olkiluoto was selected in 2000 as the site for along-term underground storage facility for Finland's spent nuclear fuel. The facility, named "Onkalo" (meaning "small cave" or "cavity")[8] is being built in thegranitebedrock at the Olkiluoto site, about five kilometers from the power plants. The municipality of Eurajoki issued a building permit for the facility in August 2003 and excavation began in 2004.[9]
The site was selected after a long process, which started in 1983 with a screening of the whole Finnish territory. From 1993 until 2000, four prospective sites were examined: Romuvaara inKuhmo, Kivetty inÄänekoski, Olkiluoto inEurajoki and Hästholmen inLoviisa. Besides geological and environmental considerations, the opinions of local residents were also taken into account. Eurajoki and Loviisa were singled out for being the locations with the highest local support. The former also had more favorable geographic conditions, thus in 1999 Posiva proposed it to the Finnish government as the selected location. The municipality of Eurajoki confirmed its approval of the site, and the national government ratified the decision in May 2001.[10]
Posiva started construction of the site in 2004.[11] The Finnish government issued the company a licence for constructing the final disposal facility on 12 November 2015.[12] The site began testing and trials in August 2024, when empty fuel canisters were placed inside the burial chambers.[13]
The facility was constructed by and will be operated byPosiva, a company owned by the two existing producers of nuclear power in Finland,Fortum andTVO. (Fennovoima, a company which was planning its first nuclear reactor, is not a stockholder of Posiva.)
The facility's constructions plans are divided into four phases:[citation needed]
Once in operation, the disposal process will involve placing twelve fuel assemblies into aboron steel canister and enclosing it in a copper capsule. Each capsule will then be placed in its own hole in the repository and overpacked withbentonite clay. The estimated cost of this project is about €818 million, which includes construction, encapsulation, and operating costs. The State Nuclear Waste Management Fund has approximately €1.4 billion from charges for generated electricity.[16]
The Onkalo repository is expected to be large enough to acceptcanisters of spent fuel for around one hundred years. At this point, the final encapsulation and burial will take place, and the access tunnel will be backfilled and sealed.
In 2012, a research group at theRoyal Institute of Technology in Stockholm, Sweden, published research suggesting the copper capsules are not as corrosion-proof as the companies planning the repositories claim (seeKBS-3).[17] This was refuted when SKB undertook follow-up studies, which indicated that the alleged corrosion process does not exist, and that the initial experiments were not correctly executed and/or the wrong conclusions were drawn.[18][19] In 2019, another study concluded that radiation effects should not significantly damage the canisters during 100,000 years.[19]
Thespent nuclear fuel has 94% of the original energy content.[20] Spent nuclear fuel is a valuable resource that can be utilized inbreeder reactors, and several other components also have useful applications. The fissile Plutonium-239 content could contribute to humanity's conversion to clean and reliable energy into the future, and burying it in permanent sealed storage would limit that potential.[21]
Danish director Michael Madsen has co-written and directed a feature-length documentaryInto Eternity (2010) where the initial phase of the excavation is featured and experts interviewed. The director's special emphasis is on thesemiotic difficulties in meaningfully marking the depository as dangerous for people in the distant future.[22][23]
American anthropologistVincent Ialenti has written a bookDeep Time Reckoning (2020) that explores how Onkalo repository "safety case" experts envisioned distant future ecosystems and reflected on the limits of human knowledge. His book is based on 32 months of in-person fieldwork in Finland.
American singer and songwriterEmperor X used a sketch of the facility as the album art for the related song "10,000-Year Earworm to Discourage Resettlement Near Nuclear Waste Repositories".
Posiva expected construction work on the repository to start in late 2016 and operations to begin in 2023
61°14′06″N21°28′56″E / 61.23513°N 21.4821°E /61.23513; 21.4821 (Onkalo entrance)
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