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Friday, October 10, 2008: 9:25 AM
Laughlin I (Flamingo Las Vegas)
A proposed scenario for nuclear waste disposal in Sweden, Finland and Canada entails emplacement of copper containers deep in granite rock. Copper is selected for the fabrication of these containers primarily for its thermodynamic stability in the aqueous anoxic environments anticipated in such repositories. However, the formation of sulphide films can destabilize copper leading to its corrosion in water at very negative corrosion potentials.
Electrochemical impedance spectroscopy (EIS) has been used to investigate properties of sulphide films grown electrochemically on Cu in anoxic chloride solutions containing sulphide ([S]total =10-4 to 10-3 mol/L). EIS spectra are fitted with different equivalent circuits, containing one to three time constants, depending on the potential at which the films were grown and [S]total. EIS data indicates that film growth can follow two distinct pathways. The initially formed film grows rapidly via an ion (or associated defect) transport process. If this film remains coherent, subsequent film growth / corrosion is extremely slow. More commonly, the development of interfacial stresses leads to film fracture, allowing the growth of a thicker outer nodular deposit via ion transport throughout fractures and pores. Such a scenario is favored at large anodic potentials and high [S]total, and results in continued corrosion.
Electrochemical impedance spectroscopy (EIS) has been used to investigate properties of sulphide films grown electrochemically on Cu in anoxic chloride solutions containing sulphide ([S]total =10-4 to 10-3 mol/L). EIS spectra are fitted with different equivalent circuits, containing one to three time constants, depending on the potential at which the films were grown and [S]total. EIS data indicates that film growth can follow two distinct pathways. The initially formed film grows rapidly via an ion (or associated defect) transport process. If this film remains coherent, subsequent film growth / corrosion is extremely slow. More commonly, the development of interfacial stresses leads to film fracture, allowing the growth of a thicker outer nodular deposit via ion transport throughout fractures and pores. Such a scenario is favored at large anodic potentials and high [S]total, and results in continued corrosion.
See more of: PES-3: Corrosion in Nuclear Waste Storage and Disposal
See more of: Public and Environmental Safety
See more of: Public and Environmental Safety