The Mechanism of Sulphide Film Growth on Copper in Anaerobic Sulphide Solutions Under Natural Corrosion Conditions

Abstract

Since copper is stable under aqueous anaerobic conditions, it is a primary candidate material for the fabrication of high level nuclear waste containers to be emplaced in deep geologic waste repositories. Once the oxygen trapped in the groundwater on repository closure is consumed, the only available oxidant would be sulphide, present in groundwater due to either mineral dissolution (i.e. pyrite, FeS2) or produced by the action of sulphate reducing bacteria. Corrosion would then be controlled by either the diffusive transport of sulphide through the compacted clay buffer surrounding the canister, or by the expected protective properties of the copper sulphide layer on the canister surface [1]. This makes a knowledge of the growth mechanism of the sulphide film formed on the copper surface under natural corrosion conditions essential for the performance assessment of copper nuclear waste canisters under deep geologic repository conditions.