[en] Both Sweden and Finland has advanced plans for design, construction and operation of the final repositories for direct disposal of spent nuclear fuel. Both countries have the same type of host rock - granite. They are also investigating alternative concept for disposal, vertical or horizontal disposal of the canisters with encapsulated spent nuclear fuel, normally called KBS-3V or the KBS-3H disposal concept. The development of the KBS-3V concept started around 1980 and is the reference method for both SKB in Sweden and Posiva in Finland. However, extensive development work is ongoing since 2001 with KBS-3H in order to bring that concept to the same maturity as KBS-3V. This presentation deals with the design and operation of the KBS-3V based on the work done within Sweden and SKB but the development is Finland is identical and it is a close cooperation between SKB in Sweden and Posiva in Finland. In Sweden, the site investigation for location of the repository has been concentrated on two sites, in the Oskarshamn area, about 350 km south of Stockholm, and the Forsmark area, about 180 km north of Stockholm. For information it can be mentioned that Finland plans to locate their repository in the vicinity of the Olkiluoto nuclear power plant site, about 300 km north of Helsinki. The site investigation is completed and the selection of site is scheduled to mid 2009 and sending in the application for location and construction of the repository is scheduled to end 2009. After receiving all necessary permits, construction time and commissioning will take about 7 to 8 years and operation is expected to start about 2020. The KBS-3 system is based on a multi barrier concept and the work with compiling the design requirements for the underground part of the deep repository has been ongoing for some time within the SKB organisation. Today the design requirements for the underground part are documented in a big number of reports that has been produced by specialists and working groups over rather a long time period. For each barrier the following will be determined during the development work: specification; design determining parameters; dependency on other parts of the repository barriers; design determining situations during construction and operation; and design determining processes after closure of the repository. For the design and optimisation of the different parts of the disposal concept the following has to be considered: long term safety after closure; safety during operation; safety during construction; environment issues; technology and feasibility; costs; possibility to retrieve the canisters with spent fuel. Over the years, a number of generic studies of the layout of the operational area(s) above ground and underground facilities of the repository have been performed. Different access routes from the ground level to the repository level at 500 m below ground have also been investigated. The access routes studied are mainly by shafts only or a ramp access for the heavy and bulky transports in combination with different service shafts. Further, a ramp alternative could be arranged as a spiral or as a straight ramp in combination with service shafts. The selected reference alternative with a combination of shafts and a spiral ramp is illustrated. In the evaluation process of the access routes it is important to have a good knowledge of the cost and time schedule for shaft sinking down to the repository level in order to compare this with a ramp access. The time needed for the excavation of the shaft down to the repository level will be about 18 months shorter comparing with ramp. Other factors that may influence the selection between access routes are constructability, operational safety and long term safety. In the reference case, the deposition tunnels are separated by 40 metres and the spacing between the deposition holes is six metres. The latter distance is determined by the need to limit the temperature on the canister surface. The operational area comprises a terminal building for receiving transport casks containing encapsulated fuel, a production building for preparation of buffer and backfill material, a supply building for electric power supply, buildings for offices and personnel and a restaurant building. When all canisters in one deposition drift have been emplaced the backfilling and final sealing of the drift can start. It has been discussed to carry out stepwise backfilling but the reference is that we do the backfilling in one step. The backfilling will be done with pre-compacted blocks of swelling clay and with some additional pellets for filling the void between the blocks and the rock wall and the roof of the drift. The principle for emplacement of the blocks is still not decided but different methods and equipment will be tested. The backfilling of the about 300 m long disposal drifts will be a challenge. The speed for backfilling must be high as we must avoid piping and problem with water. We plan to take down about 350 - 400 tons of backfilling material per 24 hours. The backfilling of one drift is estimated to take 10 - 12 full weeks working all days in the week and around the clock. The transport logistic for the backfill material from the production building in the operational area on ground down to the repository level and out into the drift and feeding to the emplacement equipment as well as filling the void between the blocks and the walls and the roof will not be an easy task. When the backfilling is completed it is time for construction of the sealing plug. SKB is investigating different designs of this plug. The plug will be a cast low-pH concrete plug but it is still open if it will be a short reinforced plug or a longer taped plug or if we need a bentonite plug between the backfill and the concrete construction. (author)