Aspo lab brings final repository closer

Wednesday, 10 October 2007 Due to an error outside its control, WNN mistakenly believed this development to have taken place on 10 October 2007. In fact it took place as currently dated, 29 March 2007.

SKB, Sweden's radioactive waste management company, inaugurated a new research laboratory on 29 March to conduct large-scale tests on a vital component of its final repository for used nuclear fuel.

The bentonite laboratory at Aspo, north of Oskarshamn in eastern Sweden, complements the Aspo Hard Rock Laboratory (HRL) where ten years of research into Sweden's planned final repository for used nuclear fuel has already been carried out. It will perform research on the properties and handling of bentonite clay.

Bentonite is a volcanic clay that swells and seals out water, but also remains flexible. These properties make it the material of choice for several functions in a final repository. It can act as a safety barrier surrounding the canisters containing used fuel, as well as protecting them from corrosion and rock movements. It can also be used to backfill deposition tunnels in the repository after closure.

SKB will use the new facility to build on knowledge already gained from Aspo as well as developing industrial handling processes to suit conditions in the final repository. Aspo HRL head Mats Ohlsson described some of the investigations the new laboratory will carry out; "We will now be able to simulate different conditions that may occur in a final repository, for example different water flows. We will also be able to refine the industrial handling of the bentonite so that we can use the best available technology. Among other things, the methods for installing the bentonite around the canisters will be further developed," he said.

SKB has been studying underground disposal of nuclear waste for 30 years and has developed a method called KBS-3, which involves placing the waste in copper canisters 5 cm thick which are then embedded in bentonite and placed in a planned final repository, which will be built in bedrock at a depth of about 500 m. Studies of Swedish bedrock to find a suitable site began in the mid-1970s, and site investigations are now under way in the two eastern Swedish municipalities of Oskarshamn and Osthammar (near Forsmark), with the approbation of the relevant local authorities. Preliminary safety assessments suggest that both are good prospective sites. SKB plans to submit an application to build the final repository at its chosen site at the end of 2009.

At present, Swedish used fuel is stored in a dedicated central interim storage facility, Clab, which has been operating since 1985. SKB plans to build an encapsulation plant, where used fuel would be sealed into the canisters, adjacent to the interim storage facility.

Further information

SKB

WNA's Nuclear Energy in Swedeninformation paper
WNA's Waste Management in theNuclear Fuel Cycle information paper

WNN: Wasteencapsulation for Oskarshamn