Workreport 2012-50



Loppusijoituslaitoksen suunnitelma 2012


Saanio, T., Ikonen, A., Keto, P., Kirkkomäki, T., Kukkola, T., Nieminen, J. & Raiko, H.



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The spent nuclear fuel accumulated from the nuclear power plants in Olkiluoto in Eurajoki and in Hästholmen in Loviisa will be disposed of in Olkiluoto. Facility complex will be constructed to Olkiluoto, and it will include two nuclear waste facilities according to Government Degree 736/2008. Nuclear waste facilities are encapsulation plant constructed to encapsulate spent nuclear fuel and disposal facility consisting of underground repository and other underground rooms and above ground service spaces. The repository is planned to excavate at a depth of 400 - 450 metres. Access routes to the disposal facility are an inclined access tunnel and vertical shafts. The encapsulated fuel is transferred to the disposal facility in the canister lift. The canisters are transferred from the technical rooms to the disposal area via central tunnel and deposited in the deposition holes which are bored in the floors of the deposition tunnels and are covered beforehand with compacted bentonite blocks. Two parallel central tunnels connect all the deposition tunnels and central tunnels are interconnected at certain distances. The solution improves the fire safety of the underground rooms and allows flexible backfilling and closing of the deposition tunnels in stages at the operational phase of the repository.


An underground rock characterization facility, ONKALO, is excavated at the disposal level. ONKALO in designed and constructed so that it can later serve as part of the repository. The goal is that the first part of the disposal facility will be excavated after the phase of building permit in the 2010’s and operation will start in 2020’s. The fuel from 4 operating reactors as well the fuel from the fifth nuclear power plant under construction has been taken into account in designing of the disposal facility. According to the information from TVO and Fortum, amount of the spent nuclear fuel is 5 440 tU. Disposal facility is being excavated and closed in stages over the long operational time of about 100 years. In the expansion plans of the facility, there is a layout example for repository for 9 000 tU. This is also maximum amount of spent fuel in the Decision-in-principle regarding the final disposal of spent fuel.


The designs of disposal facility are presented as located in Olkiluoto based on investiga-tion data of the bedrock. The location of the disposal facility will be revised when more information on the bedrock has been gained. More detailed data of the bedrock will be obtained with above ground investigations from investigations in ONKALO and investigations during the excavation of the repository and long operation time of the disposal facility. The facility is planned so that technical development can be flexibly utilized. The total volume of the disposal facility is approximately 1.3 million m3. The maximum open volume is around 0.8 million m3, because the disposal facility is excavated and backfilled in stages.


The disposal facility is divided into the controlled area and the uncontrolled area. Canisters are always handled and lowered to the deposition hole in the controlled area. The excavation and construction of new tunnels and the backfilling of the tunnels is carried out in the uncontrolled area. Extensive material transfers, such as transfers of excavated rock and backfilling materials are transported in the access tunnel. Separate ventilation systems are provided for the controlled and the uncontrolled area.


Spent nuclear fuel, disposal facility, repository, disposal.


Loppusijoituslaitoksen suunnitelma 2012 (pdf) (16.6 MB)


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