In order to dispose of spent nuclear fuel, SKB plans to site a deep repository and an encapsulation plant with associated canister fabrication and transportation system. One of the main tasks that has been assigned to SKB is to develop a distinct site geoscientific investigation programme. SKB has investigated the prospects of establishing a deep disposal system in either the municipality of Oskarshamn or in Northern Uppland. The disposal plans also include further study of the prospects for constructing a deep repository in the municipality of Nyköping.
In the municipality of Oskarshamn, SKB plans to carry out further studies of siting the deep repository at Simpevarp, where SKB wants to initiate the site investigations with a test drilling. For the encapsulation plant, SKB wants to continue studying a siting at the central interim storage facility for spent nuclear fuel (CLAB).
In Northern Uppland, SKB plans to study two siting alternatives for the deep repository. One is Forsmark, where SKB wants to initiate a site investigation with test drilling. The other is Tierp north/Skutskär, where SKB intends to start test drilling in an area north of Tierp. First, however, a suitable drilling area with possible transport solutions needs to be defined. This alternative requires the participation of the municipalities of both Tierp and Älvkarleby. A siting of the encapsulation plant in Northern Uppland will also be studied.
For the municipality of Nyköping, SKB plans to conduct a new safety assessment for the Fjällveden area, based on data from previous investigations as well as additional studies of how a deep repository could be arranged. SKB will gather data from yet another geographical and geological region beyond those that are prioritised. No test drilling is planned in Nyköping.
The goal of the site investigation phase is to obtain all permits needed to build the planned facilities. It will take an estimated 7-8 years to assemble the requisite supporting material, carry out consultations, compile siting applications and have these applications reviewed by the appropriate authorities.
SKB is planning to investigate at least two sites in Sweden. After concluding the site investigations, the decision on siting of the deep repository will be made. After this siting decision, then detailed characterisation can be performed on one site. By means of investigations from tunnels, the properties of the bedrock can then be determined in detail and the construction of the deep repository planned.
Certain general premises influence the programme for the site investigations. One is quantities and type of fuel to be accommodated in the repository. This, together with data on burnup and interim storage time, is of direct importance for how big the repositories will be and thus what rock volume needs to be investigated. The site investigation programme uses the KBS-3 method for the disposal of spent nuclear fuel.
The KBS-3 method was developed in the 1980s. It is a planning premise for the site investigation programmme. The main alternative of the KBS-3 method is that canisters are deposited one by one in vertical holes from the deposition tunnels. Variants that may be considered are vertical deposition of two canisters in each hole, horoizontal deposition of one canister per hole, and horizontal deposition of several canisters per hole. The present programme is also applicable to these variants.
Disposal method
After interim storage in CLAB, there are two possible main ways of dealing with the spent nuclear fuel. One entails regarding the fuel as a resource for recovery of material for new nuclear fuel. To achieve this, the spent nuclear fuel must be reprocessed.
The other way is to treat the spent nuclear fuel as waste. Several strategies and systems have been proposed for this. Some conflict with international agreements, such as disposal in deep-sea sediment, or are unrealistically costly and insufficiently reliable, such as launching into space.
Reprocessing and transmutation
Reprocessing produces a high-level waste of fission products and other long-lived nuclides. This waste requires similar final disposal as spent fuel. For economic and political reasons, reprocessing for recycling uranium and plutonium into new nuclear fuel has been dismissed as an alternative in Sweden.
Deep geological disposal
Geological disposal is a strategy that has the prospects of satisfying all requirements in international agreements and in Swedish law. The waste can be dealt with inside the country. Excessive burdens are not placed on future generations.
SKB believes that final disposal deep down in the Swedish bedrock is the only realistic alternative if this generation is to take responsibility for the waste.
Supervised storage
Supervised storage has been proposed as a strategy for storing spent nuclear fuel for several thousand years. Experience of both wet and dry interim storage for a limited duration, up to several decades, exists in many countries, including Sweden. Environmental, safety and radiation protection requirements can be satisfied as long as human supervision and institutional controls are maintained, but not otherwise. SKB judges that the proposed strategy of supervised storage violates the requirement of not imposing excessive burdens on future generations.
Evaluation
SKB evaluated the eight alternatives with respect to requirements and preferences that can be assessed today as regards the bedrock, the industrial establishment, and the societal aspects. The evaluations have been focused on the properties or conditions that are of importance for selection at this stage.
Bedrock
•All alternatives in the selection pool meet the safety requirements that can be checked now.
•The alternatives cannot be ranked in terms of safety based on what is known about the bedrock today.
•Test drilling is required to verify whether the bedrock satisfies the safety requirements. There is a risk that test drilling will reveal such conditions that a site must be abandoned.
Industrial establishment
•Simpevarp and Forsmark stand out as particularly suitable with respect to industrial establishment.
•There are good establishment prospects for several other siting alternatives, but the uncertainties are great, due for example to the need for overland transport of spent nuclear fuel and/or development of new land areas for industrial purposes.
Societal aspects
•The prospects of gaining public confidence and support for the deep repository project are difficult to assess and may change.
•It should be possible to gain public confidence and support in most municipalities, but the prospects are deemed to be particularly good for a siting at Simpevarp or Forsmark, providing that the bedrock there satisfies the safety requirements.
Site preference
SKB notes that Forsmark and Simpevarp have clear advantages from an establishment and societal viewpoint. These alternatives offer particularly good prospects for establishing and operating the deep repository’s facilities and transportation system with small and acceptable environmental consequences. They are judged to provide the best possibilities for satisfying the Environmental Code’s requirement on “least possible intrusion and detriment.” They have a good prognosis when it comes to the bedrock as well. SKB’s conclusion is that Forsmark and Simpevarp must be included as alternatives in the next phase.
In order to ensure that the programme is robust, SKB says that the continued siting studies should include more alternatives than Forsmark and Simpevarp. The next phase should therefore include studies of alternatives that have good prospects, but are different from Forsmark and Simpevarp. Additional sites should mainly represent other geological conditions and be located in other municipalities.
Of the siting alternatives, Tierp north/Skutskär and Skavsta/Fjällveden can contribute towards broadening the geological range of alternatives. SKB believes these sites should be studied further. Tierp north/Skutskär offers good industrial establishment possibilities. SKB judges this alternative to be fully realistic in all respects. There is more uncertainty over Skavsta/Fjällveden with regard to feasibility.
Other siting alternatives do not offer any obvious advantages of geological breadth. However, there is no good reason at this point to either dismiss or commence site investigations for additional alternatives. Hargshamn is the leading alternative if it should not be possible to commence site investigations in Forsmark or if the investigations show that the bedrock does not meet the requirements. Similarly, Oskarshamn south and Hultsfred constitute possible alternatives to Simpevarp.
SKB’s opinion is that a choice of Formsark, Simpevarp and Tierp north for test drilling and further study, along with additional studies of the prospects for the Skavsta/Fjällveden alternative, offers a reasonable balance between the preference of a robust programme on the one hand and a reasonable level of cost and effort on the other.
Site investigation
SKB’s goal for the site investigation phase is to obtain the permits that are needed to site and build the deep repository. Detailed characterisation will then be able to be commenced on the selected site and the repository built for an initial demonstration deposition of 200-400 canisters.
The primary task for SKB during the coming years is to assemble the necessary supporting material for the applications, carry out consultations and prepare environmental impact statements in compliance with the requirements of the law. Permit or permissibility review takes place primarily under the Nuclear Activities Act, the Environmental Code and the Planning and Building Act.
For the deep repository, investigations of the rock are required to determine whether it is possible to build the repository on one of the candidate sites and to conduct a safety assessment. It is these investigations that have given the site investigation phase its name, since they dominate the activities during this phase. The investigations of the rock also serve as a basis for configuration of the underground portions of the deep repository. Another important part of the work is to study and formulate proposals for the local design of facilities and transportation systems. The impact of the deep repository on the environment and the community will be studied. When the study results have been compiled, SKB will submit permit applications for the encapsulation plant and the deep repository.
The site investigations are divided into two main phases. Initial site investigations are performed to identify the site within a specified area that is deemed to be most suitable for a deep repository, and to determine whether the feasibility study’s judgement of the suitability of the area holds up in the light of in-depth data. They are expected to take 1.5-2 years. If the assessment still stands up, complete site investigations follow for a duration of 3.5-4 years. The purpose of the complete site investigation is to gather the material that is required to select one of the sites as the main alternative and to apply for a permit for siting of the deep repository.
Programmes for the work in Northern Uppland, Oskarshamn and Nyköping during the site investigation phase has been prepared during the first half of 2001.
The programmes were designed with respect to the state of knowledge and specific questions for each site. They also need to take into account the viewpoints of the municipality, landowners and nearby residents, as well as nature conservation and other interests. The programmme for Nyköping includes studies but not site investigations with test drilling.
The programmme for research, technical development and demonstration will continue in parallel with the site specific work.
Northern Uppland
The purpose of the programme is to gather material for a siting of the deep repository in Northern Uppland. The possibility of locating the encapsulation plant and the canister factory there will also be studied. Site investigations will be commenced near Formark. If the results here are positive, SKB intends to gather a complete body of material for a siting of the deep repository at Forsmark. The area in Forsmark being considered for site investigations is relatively small and geologically clearly demarcated. This means that the investigations will start in a situation where a site is already identified. Test drilling should therefore be able to start relatively soon after a decision has been made on site investigations.
The inland alternative in Tierp comprises a large area, about 60 km2, which means that initial efforts will concentrate on defining a more limited subarea for site investigations and studying a suitable positioning of the repository’s above-ground facility as well as suitable transport facilities.
Oskarshamn
The purpose of the programmme for Oskarshamn is to gather material for a complete deep disposal system in the municipality. The main alternative for the deep repository is to locate the above-ground facilities on the Simpevarp peninsula, with the underground facility as close as possible taking rock conditions into consideration.
Site investigations will be commenced in the area west of Simpevarp for the purpose of defining a site for complete site investigations. SKB also intends to investigate the Simpevarp peninsula itself, even though it is not prioritised from a geological viewpoint. A siting there would entail many advantages from an establishment viewpoint, and SKB therefore finds in-depth investigations of the bedrock on the peninsula warranted.
In the main alternative, the encapsulation plant is located immediately adjacent to CLAB. Canister fabrication in the municipality or region will also be studied.
Nyköping
The primary purpose of the programme in Nyköping is to study the uncertainties associated with the industrial establishment, transport questions and societal support for various alternative solutions. The proposal for a siting of the deep repository at Skavsta/Fjällveden emerged at a late stage of the feasibility study and has not been examined as well as other siting alternatives. SKB intends to continue to study the feasibility of this alternative and to try to clarify whether societal support may be forthcoming.
Questions that need to be studied are how transport is to be arranged, the rock engineering prospects of building a long connecting tunnel between Skavsta and Fjällveden, and the design of the operating area that should be established in the Fjällveden area. The programme also includes performing a safety assessment with modern methods based on existing data from Fjällveden.
The future prospects
The Swedish Nuclear Power Inspectorate will review the programme in a similar way to how it reviews a regular decommissioning programme. An important element in this is the public hearings which SKB plans to hold as part of its reviewing procedure. SKB will follow the circulation-for-comment process and its results. It will also continue the preparations for the site investigation phase.
This year, SKB will open discussions with the concerned municipalities regarding what further information they may need to arrive at a decision on whether they wish to participate in the continued programme. Provided that the material now being presented can be processed by the regulatory authorities and the government in keeping with the stipulated timetable and with a positive outcome, it is SKB’s opinion that the municipalities should be able to arrive at a decision on the programmes by the end of 2001.
In conjunction with the transition to the site investigation phase, SKB will submit a formal notification pursuant to the Environmental Code to the concerned county administrative boards. This means that so-called extended consultation with environmental impact assessment can be started after the county administrative board’s processing of the matter. This means that SKB will consult with concerned parties regarding the siting, design and environmental impact of the deep repository, the scope of the activities and the form and content of the environmental impact statement in accordance with the provisions of the Environmental Code.
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