Onkalo Spent Nuclear Fuel Repository

Justin Adamson
February 24, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: The deep, labyrinthine design of the Onkalo repository. (Source: Wikipedia Commons)

Finland currently operates two nuclear power plants, at Olkiluto and Loviisa, providing about 25% of the country's electricity supply. [1] Like all conventional nuclear power plants, the reactors at these plants create nuclear waste in the form of spent nuclear fuel. Managing and disposing of this waste is a serious environmental challenge, to which there have been many proposed solutions and towards which there has not been much progress. [2] However, Finland is notable for being the country furthest along towards a practicable solution. [3] This solution is the Onkalo underground spent nuclear fuel repository, located in Eurajoki near the Olkiluto nuclear power plant.


The most notable aspect of the Onkalo storage facility is the fact that it is actually able to materialize. As demonstrated by the case of the proposed Yucca Mountain facility in the United States, overcoming local and political resistance to siting a storage facility can be a near-insurmountable hurdle. [4] As part of overcoming this hurdle, the company tasked with creating the facility (Posiva Oy) involved the communities at the sites under consideration from an early data, holding public meetings even as impact assessments were being undertaken. [5] As the siting process proceeded, focus shifted from geological (i.e. technical) factors to social and environmental factors. [6] The company committed to working closely with the municipality, emphasizing potential revenues, and negotiating an economic benefits package. [6] The net result was that the chosen municipality, Eurajoki, agreed to host the site in a local vote.


The Onkalo facility is a deep underground storage facility, described as a "massive underground tomb." [7] 42 kilometers of tunnels, diagrammed in Fig. 1, will burrow hundreds of meters into the bedrock, where up to 6,500 tons of waste can be stored in iron cats within copper storage canisters. The idea of such a facility is to store the waste safely underground, out of human reach, long enough for it to become harmless: a timeline on the order of tens of thousands of years. [8] Not everyone is certain that the Onkalo facility can safeguard the waste for that long, though the Finish government and the Posiva Oy company believe it can. [7] They plan to operate the facility and bury waste in it until the 2120s, after which they will seal the repository, and hope it will remain safely sealed for 100,000 years. [7]

Posiva still has not decided whether to include warning markers on the site. [9] Communicating the danger of a nuclear storage site to future generations who may have forgotten about it is a major consideration. But it is not clear if even trying to do this is a good option, with some believing it is best to simply leave no trace that the site even exists at all. [9] Given that warnings to future generations, like those on the tombs of pharaohs in the Pyramids of Egypt, are just as likely to be viewed as challenges than to actually be heeded, leaving no warning might not be such a bad choice.

Construction Progress

The three shafts have already been completed, totaling about 5 kilometers of tunnels to the full final depth of the facility. With the final approvals having been received in late 2015, work has begun on the remaining 37 kilometers of tunnel.

© Justin Adamson. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] "Nuclear Energy in Finland," Government of Finland, Minsitriy of Employment and the Economy, Energy Department, September 2011.

[2] X. Xie, "Disposal of Nuclear Waste: Methods and Concerns," Physics 241, Stanford University, Winter 2013.

[3] A. Sharif, "Spent Nuclear Fuel in the U.S., France and Finland," Physics 241, Stanford University, Winter 2011.

[4] B. Li, "Yucca Mountain: A Case-Study in Political Treatment of Nuclear Waste," Physics 241, Stanford University, Winter 2016.

[5] C. de Saillan, "Disposal of Spent Nuclear Fuel in the United States and Europe: A Persistent Environmental Problem," Harvard Environ. Law 34, No. 2 461 (2010).

[6] M. Kojo, M. Kari, and T. Litmanen, "The Socio-Economic and Communication Challenges of Spent Nuclear Fuel Management in Finland: The Post Site Selection Phase of the Repository Project in Eurajoki," Prog. Nucl. Energy 52, 168 (2010).

[7] Z. Turner, "A 100,000-Year Tomb for Finland's Nuclear Waste ," Wall Street Journal, 24 Jan 17.

[8] E. Goldstein, "Nuclear Waste Fundamentals," Physics 241, Stanford University, Winter 2012.

[9] S. Rose, "Nuclear Waste: Keep Out For 100,000 Years," The Guardian, 24 Apr 11.