POSIVA Report 2016-19



KBS-3H Disposal Facility Description


Posiva Oy



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The purpose of the facility description is to provide a specific summary of the scope of Posiva’s KBS-3H disposal facility in Olkiluoto. This facility description is based on the corresponding description of a KBS-3V facility and considers the specific characteristics of the KBS-3H design. The facility description depicts the foreseen disposal facility and its operation as the disposal of spent nuclear fuel starts in Olkiluoto in the 2020s.

According to the decisions-in-principle of the government, the spent nuclear fuel from Loviisa and Olkiluoto nuclear power plants in operation and in future cumulative spent nuclear fuel from Loviisa 1 and 2, Olkiluoto 1, 2, 3 and possible 4 nuclear power plants, is permitted to be disposed of in Olkiluoto bedrock. 

The design of the disposal facility in this report is based on the KBS-3H concept (horizontal disposal). The long-term safety concept is based on the multi-barrier principle i.e. several barriers to prevent release, which mutually ensure that insufficiency in the performance of one barrier does not jeopardize safety after closure. The barriers for KBS-3H are the following: canister, bentonite buffer, filling components, compartment plugs and drift plugs, closure (including backfill of tunnels) and the natural barrier offered by the host rock of the repository. The canisters, together with bentonite buffer are installed in supercontainers made up of an outer surrounding titanium shell, and emplaced in near horizontal deposition drifts. Between individual supercontainers, bentonite buffer is emplaced as distance blocks. The buffer both in the supercontainers and in the distance blocks is composed of compacted bentonite blocks, which swell after absorbing water. The bentonite filling components, surrounding bedrock and the central and access tunnel backfill provide additional retardation of possible radionuclide releases.

The nuclear facilities consist of (an encapsulation plant and) an underground disposal facility including other aboveground buildings and surface structures serving the facility. The spiral access tunnel and the ventilation shafts to the disposal facility and some auxiliary rooms were constructed as a part of the ONKALO underground rock characterization facility during years 2004–2014. The construction works needed for the repository start after obtaining the construction license. The operating phase commences in the early 2020s after obtaining an operating license. Additional deposition drifts and central tunnels are bored and excavated as the disposal successively proceeds. 

The spent nuclear fuel is transferred into the underground disposal facility with a canister lift. According to the current design, the repository layout is based on one-storey layout alternative at the level of -400... -450m. The underground disposal facility is accessed by the access tunnel and a personnel shaft, which is located in a hoist building.

The KBS-3H design has been developed jointly by SKB and Posiva since 2002. In this report a short description of SKB’s system and some differences between the two organisations are described in a separate chapter. This report has been prepared within the project phase “KBS-3H - System Design 2011-2016”.


Spent nuclear fuel, KBS-3 concept, facility description, disposal, disposal facility, repository, release barrier


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