Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG The Swedish NGO Office for Nuclear Waste Review

Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG The Swedish NGO Office for Nuclear Waste Review (MKG) Box 7005, SE-402 31 Göteborg, SWEDEN, Tel: +46 31 7110092, Fax: +46 31 7110093 www.mkg.se Johan Swahn, Ph.D., Director The Swedish NGO Office for Nuclear Waste Review (Miljöorganisationernas kärnavfallsgranskning, MKG) e-mail: johan.swahn@mkg.se, mobile: +46 70 4673731 The Finnish/Swedish high-level waste disposal concept and its problems

The KBS method for a final disposal of spent nuclear fuel Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG Planned repository in Forsmark in Sweden Planned repository in Olkiluoto in Finland The development of the KBS method for final disposal of spent nuclear fuel was started in Sweden in 1977. Finland is implementing a copy of this system. The method is still not approved in Sweden, but an application for a licence is due in 2010.

The development of the KBS method for final disposal of spent nuclear fuel was started in Sweden in 1977. Finland is implementing a copy of this system.

The method is still not approved in Sweden, but an application for a licence is due in 2010.

The KBS Method Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG Source:SKB AB/ Jan M Rojmar - Grafiska Illustrationer 300-700 m Source:SKB AB/Mats Jerndahl

The KBS Method: Long-term Environmental Concerns A final repository for spent nuclear fuel can not be allowed to release radioactivity that harms the ecosystems for a period of several hundreds of thousands of years. Planned geologic repository in Swedish and Finnish bedrock at a depth of 400-500 m has groundwater flowing through the repository. A repository using the KBS method therefore has to rely on man-made artificial barriers (clay and copper) to isolate the nuclear waste from the environment. The chemical environment will in the long term interact with the biological environment (bacteria and virus) in ways that are difficult to foresee and may threaten the man-made barriers. The long-term function of the clay barrier is very dependent on the initial saturation with water close to a hot copper surface. Recent findings imply that at higher temperatures copper corrodes in oxygen-free water. The copper canisters are hot for several thousand years. Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG

A final repository for spent nuclear fuel can not be allowed to release radioactivity that harms the ecosystems for a period of several hundreds of thousands of years.

Planned geologic repository in Swedish and Finnish bedrock at a depth of 400-500 m has groundwater flowing through the repository.

A repository using the KBS method therefore has to rely on man-made artificial barriers (clay and copper) to isolate the nuclear waste from the environment.

The chemical environment will in the long term interact with the biological environment (bacteria and virus) in ways that are difficult to foresee and may threaten the man-made barriers.

The long-term function of the clay barrier is very dependent on the initial saturation with water close to a hot copper surface.

Recent findings imply that at higher temperatures copper corrodes in oxygen-free water. The copper canisters are hot for several thousand years.

Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG Researchers at the Royal institute of Technology, KTH, in Stockholm published a new article of the corrosion of copper in oxygen-free environments in 2007

Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG The same researchers published a 15-year study of the corrosion of copper in oxygen-free environments in 2008

Johan Swahn – Kopparkorrosion 090224

Johan Swahn – Kopparkorrosion 090224

Confirmation of problem at the Hard Rock Laboratory in Äspö/Oskarshamn Johan Swahn – Kopparkorrosion 090224

Johan Swahn – Kopparkorrosion 090224

Summary of Implications of the Problem of Copper Corrosion in an Oxygen-Free Environment The discovery of corrosion of copper in oxygen-free environments threatens the long-term security of the implementation of the KBS method for final disposal of spent nuclear fuel If groundwater is readily available at the site (Oskarshamn and Olkilouto) the copper canisters will likely be destroyed during the first thousands of years when they are hot If the hydrogen produced in the reaction causes brittleness in copper the canisters may collapse faster, perhaps during the first hundreds of years In very dry rock (Forsmark) the severity of the problem needs to be examined further, but it looks unlikely that long-term security can be established The oxygen-free corrosion process need to be understood further Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG

The discovery of corrosion of copper in oxygen-free environments threatens the long-term security of the implementation of the KBS method for final disposal of spent nuclear fuel

If groundwater is readily available at the site (Oskarshamn and Olkilouto) the copper canisters will likely be destroyed during the first thousands of years when they are hot

If the hydrogen produced in the reaction causes brittleness in copper the canisters may collapse faster, perhaps during the first hundreds of years

In very dry rock (Forsmark) the severity of the problem needs to be examined further, but it looks unlikely that long-term security can be established

The oxygen-free corrosion process need to be understood further

For more information ... Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG www.mkg.se

Johan Swahn, The Swedish NGO Office for Nuclear Waste Review, MKG Johan Swahn, johan.swahn@mkg.se, 070-4673731 The Swedish NGO Office for Nuclear Waste Review