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Chemical Durability of Copper Canisters Under Crystalline Bedrock Repository Conditions

Published online by Cambridge University Press:  15 February 2011

Rolf Sjöblom ,
Hans-Peter Hermansson  and
Örjan Amcoff
Rolf Sjöblom
Affiliation:
Swedish Nuclear Power Inspectorate, Box 27 106, S-102 52 Stockholm, Sweden
Hans-Peter Hermansson
Affiliation:
Studsvik Material AB, S-611 82 Nyköping, Sweden
Örjan Amcoff
Affiliation:
University of Uppsala, Institute of Geology, Department’ of Mineralogy and Petrology, Box 555, S-751 22 Uppsala, Sweden
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Abstract

In the Swedish waste management programme, the copper canister is expected to provide containment of the radionuclides for a very long time, perhaps millions of years. The purpose of the present paper, is to analyse prerequisites for assessments of corrosion lifetimes for copper canisters.

The analysis is based on compilations of literature from the following areas: chemical literature on copper and copper corrosion, mineralogical literature with emphasis on the stability of copper in near surface environments, and chemical and mineralogical literature with emphasis on the stabilities and thermodynamics of species and phases that may exist in a repository environment.

Three main types of situations are identified: (1) under oxidizing and low chloride conditions, passivating oxide type of layers may form on the copper surface; (2) under oxidizing and high chloride conditions, the species formed may all be dissolved; and (3) under reducing conditions, non-passivating sulfide type layers may form on the copper surface.

Considerable variability and uncertainty exists regarding the chemical environment for the canister, especially in certain scenarios. Thus, the mechanisms for corrosion can be expected to differ greatly for different situations. The lifetime of a thick-walled copper canister subjected to general corrosion appears to be long for most reasonable chemistries. (It is assumed that the canister has no defects from manufacturing and that the bentonite buffer is intact). Localized corrosion may appear for types (1) and (3) above but the mechanisms are widely different in character. The penetration caused by localized corrosion can be expected to be very sensitive to details in the chemistry.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 353: Symposium – Scientific Basis for Nuclear Waste Management XVIII , 1994 , 687
Copyright
Copyright © Materials Research Society 1995

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References

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