Disposal of operational waste and waste from research reactors

Finland, Norway and Sweden have repositories in operation for LLW and ILW. In 1983 the Swedish nuclear power companies received permission from the government to construct and operate a repository for short-lived LLW and ILW. This repository was built near the reactor site in Forsmark. It has been in operation since 1988 and was at the time the first of its kind in the world.

The repository, which is called SFR, is located at a depth of 50 m under the bottom of the Baltic Sea (Fig. 13.2). It consists of four rock vaults and a 50 m high, 25 m diameter concrete silo. The space between the silo and the host rock is filled with bentonite clay to avoid water flow outside the silo. It is used for the ILW, while the vaults are used for the LLW. The current capacity of the facility is 63,000 m3 and it receives about 600 m3 a year. It is at present filled to half its capacity. SFR also receives RAW from hospitals, industry and research laboratories. This waste, which is first conditioned at Studsvik, constitutes only a small fraction of the total waste, typically 10-20 m3 per year. The main types of waste containers are 200 litre steel drums, concrete or steel moulds (cubes with 1.2 m sides) and concrete tanks (3.3 x 1.3 x 2.3 m). The matrix for solidification is either concrete or bitumen (Riggare and Johansson, 2001).

Today, there is a need for an additional capacity of 20,000 m3 to accom­modate the decommissioning wastes from the dismantling of the reactors at Barseback, Agesta and Studsvik (Fig. 13.1). An additional 100,000 m3 will be necessary for the decommissioning waste from the remaining Swedish reactors. This, however, will not be needed until some time between 2030 and 2045. The current plans are to submit an application for the extension of SFR by 2013 and to have the extended repository in full operation by 2020.

In Finland, each power company takes care of its own reactor waste. Teolisuuden Voima’s (TVO) repository in Olkiluoto consists of two vertical silos at a depth between 60 and 100 m below the surface (Fig. 13.3) (Aikas and Anttila, 2008). One of the silos is for ILW and the other for LLW. The repository has the capacity to accommodate the volumes of waste produced during the 40 years of expected operation of the existing plants at Olkiluoto. The silo for ILW has a concrete lining. Both silos are 34 m high with a diameter of 24 m. The annual amount of reactor waste is in the order of

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13.2 Photomontage showing the Forsmark reactor site and the underground parts of the SFR repository in Sweden. Existing parts to the right and the planned expansion to the left (from SKB’s Brochure ‘SKB bygger ut SFR’. Illustrator: LAJ Illustration, Photographer: Lasse Modin).

100-200 m3. Compressible waste is packed into 200 litre drums using a hydraulic press. The drums are then compacted into half the original length. Non-compressible waste is packed into steel or concrete boxes or waste drums. The intermediate-level ion-exchange resins are solidified in bitumen and packed into drums (Aikas and Anttila, 2008; Posiva, 2010).

The Loviisa repository has two tunnels 106 m long with a cross section of 30 m2 for solid LLW. The ILW is deposited in an 84 m long cavern with a cross section of 300 m2 (Fig. 13.4). The repository is at a depth of 110 m

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13.3 The layout of the reactor waste repository at Olkiluoto in Finland (from www. posiva. fi).

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13.4 The layout of the reactor waste repository at Hastholmen, Loviisa in Finland (from Aikas and Anttila, 2008).

below the surface. Dry maintenance waste is packed in 200-litre drums and if the waste is compressible it is also compacted. Spent ion-exchange resins and bottoms sludges from evaporators are stored in tanks in liquid waste storage. A facility for solidifying this waste in cement was completed in 2007 (Aikas and Anttila, 2008; Posiva, 2010).

In 1989 the Norwegian government instructed a committee to investigate the possibilities for disposal of LLW and ILW in Norway. This resulted in 1992 in an impact assessment for three possible sites with the outcome that a site at Himdalen was recommended. Himdalen is situated 25 km from the waste treatment facility at the Institute for Energy Technology (IFE) in Kjeller. It was later decided that the facility should serve for final disposal of LLW and ILW and as storage during its operational time for some plu­tonium-bearing waste. At the time for closure of the repository, it will be decided if that waste should be removed or conditioned in concrete and disposed of. The operation of the facility started in 1999. The repository consists of four rock caverns accessed by a 150 m tunnel. The rock cover is 50 m. The waste is packed in 210 litre drums. The total capacity of the facility is 10,000 drums. The drums are put in a concrete ‘sarcophagus’ and encased in cement. High-level waste and nuclear fuel will not be disposed of in Himdalen (SOrlie, 2001).

By 1970 waste barrels were being disposed of at IFE in a 4 m deep trench covered by a 2 m thick clay layer. Apart from this clay layer, this disposal facility has no engineered barriers. The current plans are to retrieve this waste, condition it and dispose of it in the Himdalen facility (Sorlie, 2001).

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