Site selection for repositories for spent fuel

The siting of a Swedish repository for spent nuclear fuel was a process that took nearly 20 years (SKB, 2011). As for the fuel management, the Stipula­tion Act of 1977 started the activities. The law required that the reactor owners show how and where the nuclear waste could be safely disposed of before reactors could be fuelled. From 1977 to 1985, SKB and the National Council for Radioactive Waste (PRAV, which existed between 1975 and 1981) performed site studies at eight locations, referred to as ‘study sites’. Other sites were also investigated, but in some cases the local resistance was so great the studies had to be interrupted (see Fig. 13.5). Nevertheless, the investigation generated a large body of data. The main result of the study site investigations was that it is possible to find many places in Sweden where the geological conditions are suitable for building a repository for spent nuclear fuel. An important conclusion from these studies was that suitability of a site is related mainly to the local conditions and not so much to a special geological environment within the bedrock. Another lesson was that the acceptance of the local population is essential for the siting work.

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13.5 Places in Sweden where investigations were conducted into potential repository sites during the period from the mid-1970s until 1990 (from SKB Report R-11-07).

About 1990, SKB established the Aspo Hard Rock Laboratory (Aspo HRL) near the Oskarshamn nuclear reactors. Collecting more data from study sites was considered not to add much to the existing knowledge. Instead it was important to develop, demonstrate and test the KBS concept and the investigation methods to be used in evaluating sites for a possible repository for spent nuclear fuel.

The stage in the siting process, referred to as feasibility studies, started in 1992 and was completed in 2000. During that period SKB approached more than 20 municipalities to discuss the possibilities of performing feasibility studies there (see Plate IV between page 448 and 449). In eight of those, SKB performed feasibility studies. The first sites to be studied were Storuman and Mala. The studies showed that both sites had favourable conditions, but after local referenda these counties decided not to partici­pate in further studies. In parallel with these studies, SKB also explored the possibility of siting a repository in municipalities that already had nuclear installations. In Kavlinge (Barseback NPP), the geology was deemed unfavourable and in Varberg (Ringhals NPP), the municipality declined to participate. Studies were, however, carried out in Osthammar (Forsmark NPP), Oskarshamn (Oskarshamn NPP) and Nykoping (Studsvik nuclear laboratories). Some neighbouring municipalities showed interest and studies were also performed in Tierp, Alvkarleby and Hultsfred. With the exception of Alvkarleby, SKB concluded that all locations provided favour­able conditions for siting a repository. In 2000 SKB concluded that enough data were now available to enter into the next stage of site investigations. To select sites for the site investigations, the main factors considered were the quality of the bedrock, the possibilities for an industrial establishment in the area and political and popular support in that municipality.

Based on these considerations, SKB decided to include in the programme for site investigation phase the following:

• site investigation in Forsmark (Osthammar)

• site investigation in Simpevarp (Oskarshamn, this site also included the area later referred to as Laxemar)

• site investigation in the northern part of Tierp Municipality

• further study of the siting prospects in Fjallveden (Nykoping Municipal­ity). The municipality, however, declined to participate further in the siting process.

In November 2001, the government approved SKB’s programme for site investigation with the exception of Nykoping, since it had already with­drawn from the process. The next step was to achieve approval to continue from the remaining three municipalities. Both Osthammar and Oskarshamn gave their approval, but Tierp declined further participation in the siting process. Following this decision SKB started site investigations in Forsmark and Simpevarp/Laxemar in the spring of 2002. Soon into the site investiga­tion, Laxemar became the preferred site in the Oskarhamn alternative. The investigation finished in 2007 and was followed by a two-year long evalua­tion period.

In June 2009, SKB chose the Forsmark site as the site for a repository for spent nuclear fuel. The decisive factor was that from a long-term safety perspective Forsmark was undoubtedly the best alternative. The rock at Forsmark has fewer water-conducting fractures and also had lower perme­ability than the rock at Laxemar. The rock at Forsmark also provided better conditions for constructing a repository. The industrial prospects, however, for establishing and operating the final repository were good at both sites and local support for establishing a repository in the municipality was also strong at both sites. The repository was to be designed for disposal of about 6,000 canisters. The canisters have a 5 cm thick outer copper shell for cor­rosion protection and a cast iron insert for mechanical stability (Fig. 13.6). These canisters will be placed in vertical deposition holes at the bottom of horizontal access tunnels and surrounded by compacted bentonite clay. A possible layout for the repository is shown in Fig. 13.7.

Following this decision, SKB submitted an application on 16 March 2011 to the Swedish Radiation Safety Authority (SSM) and to the Environmen­tal Court in Stockholm to build a nuclear fuel repository in Forsmark and an encapsulation plant in Oskarshamn (where spent nuclear fuel will be placed in copper canisters). The main task of the Swedish Radiation Safety Authority is to decide whether the facilities comply with the Swedish

image36

13.6 SKB s reference canister. The canister is about 5 m long with a diameter of about 1 m. The maximum weight is about 27 tonnes with full fuel load (from SKB Report TR-10-14. Illustrator: LAJ Illustration).

Подпись: Rock heap
image050
Подпись: Ventilation
Подпись: Ventilation

image37"Central area

13.7 Repository for spent nuclear fuel in Forsmark, fully built-out (from SKB Report R-11-07).

Nuclear Activities Act with regard to nuclear safety and radiation protec­tion. The Environmental Court will judge the applications on the basis of Sweden’s Environmental Code.

In Finland, the site selection process started more than 30 years ago. After direct disposal of spent fuel had been selected by TVO as the option for management of high-level waste, systematic studies of the feasibility of geological disposal were started in 1978 and the first safety analysis for a spent fuel repository was published in 1982 (Anttila et al., 1982). At that time, all the work towards a repository was performed by TVO since, according to the original agreement, the Loviisa NPP was to return all spent fuel to Chelyabinsk in Russia.

In 1983, the Finnish Government made a decision in principle that the final solution in Finland will be deep geological disposal. This meant a start in 1983 on a more focused research and development programme at TVO for deep geological disposal, including site selection. The programme aimed at selecting a site in 2000 and comprised three stages (McEwan and Anttila, 2000):

• site identification surveys (1983-1985)

• preliminary site investigations (1985-1992)

• detailed site investigations (1993-2000).

The investigation surveys aimed at identifying suitable sites for preliminary site investigations. These sites were sites with suitable bedrock for con­structing a geological repository. From that pool, a small number of sites deemed to be the best suited were selected for detailed investigations.

The initial site identification used geological factors for identifying suit­able areas. The selection was based on satellite photos, geological and geo­physical maps. This led to a selection of 327 regions. Having defined these

regions, environmental and transport factors were then applied to reduce their number and areal extent. These factors were of two kinds, exclusionary and desirable (but not mandatory). The exclusionary factors concerned groundwater controlled areas, areas with high population density and national environmentally protected areas. The desirable factors concerned mainly transportation issues. Finland is in large parts sparsely populated with limited road and railway network in these areas, neither of which are necessarily designed for heavy transports. Another factor to be considered was land ownership. Areas with one or few owners were considered prefer­able to areas having many landowners.

After this selection process, 101 areas remained on the list. When the Ministry of the Environment examined the list, however, it reduced the number of investigation areas to 84 based on yet unpublished regional plans, and to that number was added Olkiluoto (the site of the Olkiluoto NPP). The Finnish Radiation and Nuclear Safety Authority (STUK) also reviewed the site selection programme and concluded that the investigation areas selected for preliminary site investigations should represent as much as possible the different geological environments in Finland.

During the review process, TVO had already started discussions with many municipalities. The starting-point was to rule out municipalities where strong opposition could be expected. Another important issue was associ­ated with the rights of the landowners and TVO decided to consider, if possible, only areas with one landowner. In early 1986, TVO announced that an area in Ikaalinen Municipality was to be the first site for preliminary site investigation. The plan was to gradually increase the number of sites to between five and seven. Although the Municipal Counsel had encouraged the site study, opposition grew rapidly and after only a few weeks TVO decided to pull out of the area.

The experience from Ikaalinen led TVO to more actively communicate with the public in the municipalities. Issues like long-term safety and pos­sible benefits to the community were highlighted. Following this approach, in 1987 TVO could announce a list of five sites that also satisfied STUK’s request for geologic versatility. These sites were (see Fig. 13.8): [1]

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13.8 Locations of the site investigations in Finland (from SKB Report P-10-46).

TVO intended to study the remaining three sites in more detail during the period 1993 to 2000. The overall goal was to be able to select at least one site for a spent fuel repository by 2000. After the new Finnish Nuclear Energy Act, Loviisa NPP could not ship its spent fuel to Russia. Spent fuel disposal in Finland was no longer a task for TVO alone. A site for disposal of spent fuel from FPH’s Loviisa reactors had to be found in Finland. Therefore, in 1995 TVO and FPH formed a joint company for nuclear waste management, Posiva Oy, which from that time was responsible for the siting, construction and operation of a spent fuel repository. A large amount of geological data was already available at the FPH’s reactor site on

Hastholmen and a pre-study showed a favourable result. Hastholmen was, therefore, included as a fourth candidate site in investigation covering the period 1997 to 1999.

At the end of the site selection programme in 1999, Posiva submitted an application according to the Nuclear Energy Act for the Government ’s Decision in Principle (DiP). In this application, Posiva stated that they had decided to proceed with further studies only at Olkiluoto. After a hearing process led by the Ministry of Trade and Industry, the government was able to make the DiP in December 2000, which was ratified by the parliament in May 2001. The DiP process included a legally binding acceptance by the Eurajoki Municipality to host the repository. It should be noted that this legal decision to host the repository cannot be changed in future. In 2003, Eurajoki Municipality gave Posiva a building permit for the underground characterization facility ONKALO. The work, which is still ongoing, started in 2004. Posiva’s current plan is to submit an application for a construction licence for turning ONKALO into the final disposal facility (Fig. 13.9) in 2012 (Posiva, 2010). The waste packages to be disposed of are essentially the same as in the Swedish repository, i. e., canisters with a 5 cm thick outer copper shell for corrosion protection and a cast iron insert for mechanical stability (Fig. 13.6). The length of the canister differs between the two coun­tries due to different fuel types at the nuclear power plants.

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