Integrated waste management in a small programme

Integrated waste management in a small programme

Nuclear Engineering and Design 176 (1997) 9 – 14 Integrated waste management in a small programme Veijo Ryha¨nen Posi6a Oy, Annankatu 42 D, FIN-00100...

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Nuclear Engineering and Design 176 (1997) 9 – 14

Integrated waste management in a small programme Veijo Ryha¨nen Posi6a Oy, Annankatu 42 D, FIN-00100, Helsinki, Finland

Abstract The Finnish nuclear waste management programme consists of handling, intermediate storage and final disposal of the spent fuel and operating waste as well as decommissioning of nuclear power plants and disposal of waste from dismantling. There are two final repositories for low- and intermediate-level operating waste, one of which is in operation at Olkiluoto and the other will be commissioned at Loviisa in 1997. A new company, Posiva, takes care of the necessary research, and later, will oversee construction and operation of the disposal facility for spent fuel. The next main target of the programme for spent fuel disposal is selection of a site in the year 2000. Construction of the final disposal facility should start during the 2010s and operation begin around 2020. © 1997 Elsevier Science S.A.

1. Introduction In Finland nuclear power plays an essential role in industry and in the whole of society, since almost 30% of the electricity consumed is produced by nuclear power plants. Arrangements for the management of radioactive wastes produced by the nuclear industry have been made since the construction phase of the power plants in the 1970s. According to Finnish legislation, the responsibility for nuclear waste management lies with the waste producers. The waste management programme consists of handling, intermediate storage and final disposal of the spent fuel and operating waste as well as decommissioning of nuclear power plants and disposal of waste from dismantling (Posiva, 1996). Although many phases of the programme will not take place for decades, the technical plans and cost estimates are regularly updated to ensure that financial provisions are made for nuclear waste management.

The next 10–15 years will be an important period in the Finnish programme, since the management of spent fuel should proceed to the phase of repository site selection and start of construction. Licensing of the spent fuel repository requires the completion of technical and scientific safety work as well as local and political acceptance. The final disposal of spent fuel is now therefore the key issue in our national programme.

2. Nuclear power programme and organisations The four nuclear power plant units operating in Finland were commissioned in the years 1977– 1981. The BWRs (2× 710 MW) at Olkiluoto in Eurajoki are owned and operated by TVO (Teollisuuden Voima Oy) and the PWRs (2× 445 MW) at Ha¨stholmen in Loviisa are owned by IVO (Imatran Voima Oy).

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Until the year 1995, strategies followed by the utilities differed in regard to spent fuel management. IVO returned spent fuel to the Russian fuel supplier, while TVO made domestic arrangements for final disposal. The Nuclear Energy Act was, however, changed in 1994 in such a way that the export of spent fuel will be forbidden after the year 1996. The utilities signed an agreement to cooperate in the management of spent fuel in May 1995. It was agreed that cooperation will be arranged within a new joint company, Posiva, which started operation in January 1996. TVO and IVO will retain the responsibility for their spent fuel and other nuclear wastes in accordance with the Nuclear Energy Act. TVO owns 60% and IVO 40% of the shares in Posiva. Posiva takes care of the necessary research, and later, will oversee construction and operation of the disposal facility. Posiva has therefore taken over the TVO programme started in the early 1980s for the disposal of spent fuel in the Finnish bedrock. Spent fuel from Olkiluoto and Loviisa will be disposed of in a common repository. In addition to its principal mission, the final disposal of spent fuel, Posiva can also carry out other expert tasks within nuclear waste management for its shareholders and also for other organisations. The company’s expertise can therefore also be utilised in the management of low- and intermediate-level wastes from the operation and dismantling of domestic power plants as well as those featuring in foreign programmes.

3. Regulatory control Regulatory bodies control and supervise the progress of the waste management programme. The Ministry of Trade and Industry within the authority of the Finnish Government is responsible for licensing of nuclear waste facilities and the Finnish Centre for Radiation and Nuclear Safety (STUK) is responsible for supervision of safety. Already in 1983 the Government made a decision on the objectives and schedules for the national waste management programme in Finland

including, e.g. selection of a site for a spent fuel repository by the year 2000 and commencement of operations in 2020. Each year the R and D programme for the following year is submitted to the Ministry of Trade and Industry for Approval. The regulatory bodies also define the necessary safety criteria for waste management. The Government approved the safety criteria for the final disposal of low- and medium-level operating waste in 1991. The Nordic authorities prepared joint recommendations for the criteria applying to high-level waste disposal in 1993. In parallel with their supervision and licensing activities, the regulatory bodies finance some R and D work independently of the programme being carried out by industry. Finnish legislation requires a so-called ‘decision in principle’ for a nuclear facility prior to the start of construction. Such a decision is requested from the Government. There are two prerequisites for each decision: a positive statement by STUK on the safety of the planned facility and approval of a local municipality for the site. Separate licences are applied for the construction and operation of a facility.

4. Management of operating wastes In the early 1980s, the power utilities decided to start arrangements for the disposal of low- and intermediate-level operating wastes on the basis that two separate repositories would be constructed at both power plant areas if the geological conditions made this possible. It was estimated that the cost difference compared to a single joint repository is marginal, but possible difficulties with acceptance could be avoided by using a solution of two repositories. Furthermore, waste resulting from the dismantling of the power plant units could then be disposed of at the site, thus minimising the need for transportation. Geological investigations started in 1980 have shown that the crystalline bedrock at both Olkiluoto and Loviisa is suitable for the final disposal of operating waste. Construction of the repository at Olkiluoto was started in 1988. This facility, called the VLJ Repository, was licensed and opened in

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1992. It will accommodate all the wastes from the operation of the Olkiluoto units and can be later extended to accept wastes from the decommissioning of these reactors as well. The VLJ Repository comprises two silos, one for low-level solid waste and the other for intermediate-level solidified waste. Both silos are situated in the bedrock 70 – 100 m below ground level. Both have a diameter of 24 m and a depth of 34 m. Wastes are packed in 200 l steel drums which are placed in concrete boxes for final disposal. Each box takes 16 drums. Larger equipment is packed in steel containers or directly in the concrete boxes. The boxes are transported to the repository on a special vehicle via an access tunnel and stacked on top of each other using a remotecontrolled crane. The concrete boxes are self-supporting and are stacked in the silos without any other supporting structures. The capacity of the repository is about 40 000 drums corresponding to 8000 m3 of waste. At the end of 1995, the silo for low-level waste contained 381 boxes and the silo for medium-level waste contained 308 boxes. This means that about 25% of the capacity has been used. Operating experience with the concrete boxes (transfer, positioning in the silos etc.) has been good. Excavations for a repository for operating waste from the Loviisa power plant were begun in 1993. The construction work is due to be completed in 1996 and the repository is scheduled for commissioning in 1997. The repository is located on the plant site in crystalline bedrock at a depth of 110 m. Maintenance waste will be disposed of in two tunnels with concrete floors and shotcreted walls. A hall for solidified waste has also been excavated. The capacity of the repository will be about 4000 m3 of waste.

5. Status of the spent fuel management programme The total estimate for the amount of spent fuel to be disposed of in Finland is about 2500 tons U. This estimate is based on an operations period of 40 years for the power plants. As this is an estimate and no decision has been taken about a

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schedule for closure of the Finnish power plants, the possibilities of extension are taken into account in the design of the facilities. Interim storage takes place at the power plant areas in water pools. At Olkiluoto there are storage pools in the reactor buildings. Furthermore, an interim storage facility (KPA Store with a present capacity of 1200 tons U) has been in operation at the power plant site since 1987. At Loviisa, the existing storage capacity will be increased by new water pools. Arrangements for the final disposal of spent nuclear fuel have been made in Finland since the early 1980s. The repository plan consists of emplacing the packaged spent fuel in vertical holes in tunnels excavated in crystalline bedrock at a depth of several hundred metres. The tunnel network will be adapted to local features of the bedrock. The present canister concept is a composite—an inner steel container and an outer container of copper. In the deposition holes the canisters are surrounded by bentonite clay which forms a buffer of very low hydraulic conductivity between the canister and the rock. The encapsulation plant will be located on the same site as the repository (TVO, 1992a). Technical plans will be updated by the end of 1996. In the main, on-going work concerns canisters, the capacity of the repository and site-specific layouts for the repository. The siting process was begun in 1983 with a country-wide survey of the principal geological features in Finland. In 1987, five areas were selected for preliminary field investigations. Results of the studies carried out so far indicate that Finnish bedrock is suitable for building a safe repository (TVO, 1992b). Detailed investigations to support the repository siting decision continue at three candidate sites: at Olkiluoto in the Eurajoki municipality, at Romuvaara in Kuhmo and at Kivetty in A8 a¨nekoski (Fig. 1). In 1994, a preliminary study was carried out on the feasibility of siting the repository in the municipality of Kannonkoski, and a similar pre-feasibility study for the power plant island of Ha¨stholmen in Loviisa will be completed by the end of 1996. Hence, both Finnish power plant areas are included in the site investigation programme. This

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principle has proved to be important in the acceptance of investigations because many inhabitants of other municipalities consider that the power plant areas should be the primary candidates for waste disposal as long as the bedrock is suitable. A post-closure safety assessment based on the present encapsulation technique and the results of site studies show that the planned disposal system fulfils the preliminary safety requirements proposed by the safety authorities. The assessment, reported in 1992, consists of two main branches, the first of which corresponds to expected evolution scenarios and the second to various cases of disruptive events and unexpected evolution (TVO, 1992a). In the next reporting stage at the end of 1996, two types of spent fuel (from Olkiluoto BWR and Loviisa PWR), updated site-specific repository layouts and new safety-related data will be included in the analysis.

Fig. 1. Candidate sites for the final repository for spent fuel.

6. Challenges for the future The next main target of the programme for spent fuel disposal is selection of a site in the year 2000. After this, approval of the Government (the so-called ‘decision in principle’) will be requested for the planned project. Prerequisites for a positive decision are that both the municipality proposed and STUK approve the plan. Finally, Parliament has to endorse the decision. The procedure mentioned above means that the approval of the local council is needed for the facility. Hence, one essential task is the distribution of information about the studies and principles of final disposal to local decision-makers and the public. Long-term communication work is needed to make people familiar with the planned project and to build confidence about the safety of final disposal. Posiva’s communication programme includes several types of activities with different target groups such as press conferences, contact group meetings with the representatives of the municipalities, open houses for the public, exhibitions, lectures to different groups, visits to the drilling sites as well as the use of a variety of written material and newspaper advertisements. Existing nuclear waste facilities offer perhaps the best possibilities to influence those who carry prejudices, but for practical reasons they can be shown to only relatively small numbers of people. In Finland, the final disposal facility will bring significant tax income and about 100 jobs to the local municipality. As for acceptance, the importance of the economic benefits will probably increase over time as the implementation phase of the schedule approaches. Nowadays, one of the main arguments against final disposal is the possible influence of the repository on the chosen municipality’s image. It is thought that the reputation of the municipality will suffer if it provides a home for the repository, and negative effects on tourism and sales of farming products are feared. In our spent fuel disposal programme the first construction project will be the building of an investigation shaft at the selected site around the year 2005. From this shaft complementary studies will be made to confirm the properties of the

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Fig. 2. Schedule for site selection and final disposal of spent fuel.

bedrock. Construction of the final disposal facility should start during the 2010s and operation begin around 2020. The time-schedule for siting and implementation is shown in Fig. 2. At a later date in the future the most significant project in the Finnish waste management programme will be the decommissioning of the power plant units. TVO’s current plans are based on deferred dismantling after 30 years of cooling, while IVO’s plan is based on dismantling soon after the end of the power plant’s service life. The radioactive wastes resulting from dismantling will be disposed of at the power plant areas in extensions of the existing repositories for operating waste. Decommissioning plans have to be updated at 5 year intervals. This procedure means that the cost estimates for decommissioning are also regularly updated in terms of their financial provisions.

7. Cost estimates and financing It is the duty of a waste producer to annually

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collect a fee in the price of electricity and set this aside to guarantee the availability of money for the future costs of waste management. The fund and the securities must cover all the future costs of the waste inventory produced. The Finnish nuclear waste management fund is administered by the Ministry of Trade and Industry. In September of each year the utilities submit to the Ministry their proposals for the liabilities to be used as a base when defining necessary payments into the fund. These liabilities are estimates of the future costs of waste management based on produced waste inventories also including, however, decommissioning costs. By the end of 1995, TVO has collected FIM 2.9 billion in the fund and IVO FIM 1.3 billion, a total of FIM 4.2 billion for both utilities. By the year 2000 the fund to cover the future costs of the Finnish programme will reach approximately FIM 6 billion. The average influence of nuclear waste management on the production cost of nuclear electricity is about 10%.

8. Concluding remarks In the Finnish nuclear waste programme, the management of low- and intermediate-level operating waste has proceeded to the implementation of final disposal. There are two repositories, one of which is already in operation at Olkiluoto, the other will be commissioned at Loviisa in 1997. At a much later date, these repositories will be extended to accommodate the waste accumulated while dismantling the power plant units. Arrangements for the final disposal of spent fuel have proceeded according to the long-term programme confirmed by the Government in 1983. In 1996, Posiva, a new company, took over the programme which had been carried out by TVO since the early 1980s. The next main goal is the selection of a final disposal site in the year 2000. In the period 2000–2010, prior to the construction phase, the licensing of the final disposal facility will begin with an application for a ‘decision in principle’ from the Government.

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An essential task in making arrangements for the disposal of spent fuel is to dispel public concern about the planned repository. Without local acceptance the implementation of final disposal will not be possible. We have to build confidence in solutions for nuclear waste management with professional scientific work, the open provision of information and a willingness to listen to the public.

References

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Posiva, Nuclear Waste Management of the Olkiluoto and Loviisa Power Plants — Annual Report, Posiva Oy, 1995. Final Disposal of Spent Fuel in the Finnish Bedrock, Technical Plans and Safety Assessment, Teollisuuden Voima Oy, Report YJT-92-31E, 1992a. Final Disposal of Spent Fuel in the Finnish Bedrock, Preliminary Site Investigations, Teollisuuden Voima Oy, Report YJT-92-32E, 1992b.