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The Corrosion Rate of Copper in a Test Parcel at the Äspö Hard Rock Laboratory

Published online by Cambridge University Press:  01 February 2011

Bo Rosborg ,
David Eden ,
Ola Karnland ,
Jinshan Pan  and
Lars Werme
Bo Rosborg
Affiliation:
Rosborg Consulting, Östra Villavägen 3, SE - 611 36 Nyköping, Sweden. KTH, Div. of Corrosion Science, Drottning Kristinas väg 51, SE - 100 44 Stockholm, Sweden.
David Eden
Affiliation:
InterCorr International, 14503 Bammel-North Houston, Suite 300, Houston, TX 77014, USA.
Ola Karnland
Affiliation:
Clay Technology AB, Ideon Research Center, SE - 223 70 Lund, Sweden.
Jinshan Pan
Affiliation:
KTH, Div. of Corrosion Science, Drottning Kristinas väg 51, SE - 100 44 Stockholm, Sweden.
Lars Werme
Affiliation:
Svensk Kärnbränslehantering AB, Box 5864, SE - 102 40 Stockholm, Sweden.
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Abstract

Cylindrical copper electrodes have been installed in a test parcel at the Äspö Hard Rock Laboratory and real-time corrosion monitoring was initiated in May 2001. The test parcel was emplaced on October 29, 1999, and will be retrieved in 2004. The three electrodes, each of about 100 cm2 surface area, are installed in bentonite block 36, where the temperature is about 24°C.

The corrosion monitoring is performed with linear polarization resistance (LPR), harmonic distortion analysis (HDA) and electrochemical noise techniques. A value on the Stern-Geary coefficient is required to calculate the corrosion rate from the measured LPR data. A default value of 10.3 mV has been used, but an actual value can in fact be obtained from the HDA. The corrosion rate will be overestimated if the frequency of the voltage perturbation for the LPR measurements is not low enough. Electrode impedance measurements have been performed to verify this.

Two and a half year after emplacement the recorded corrosion rate of copper in the above bentonite block amounts to about 2.2 μm per year (using a default value of 10.3 mV for the Stern-Geary coefficient and a 0.01 Hz voltage perturbation frequency). The actual corrosion rate is estimated to less than 0.7 μm per year (considering a measured Stern-Geary coefficient of 6.5 mV and the findings from the electrode impedance measurements).

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 807: Symposium Scientific Basis for Nuclear Waste Management XXVII , 2003 , 489
Copyright
Copyright © Materials Research Society 2004

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References

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