•Corrosion of copper in groundwater was studied with ER probes and parallel methods.•Sensitivity of the different methods (ER, LPR and weight loss) vary considerably.•ER probes gave the most ...conservative estimation of the lifetime of copper.•The trend of the corrosion rates measured with parallel methods was similar.
In this study the results from corrosion monitoring of copper in anoxic simulated ground water in the presence and absence of sulfate-reducing bacteria (SRB) enriched from the planned disposal site of high level nuclear waste are presented. Copper electric resistance (ER) probes were applied as a physical tool for monitoring corrosion of copper disposal canister. The results are compared to those obtained by linear polarization resistance (LPR) measurements, conducted for parallel OFP-Cu specimens during the experiments, and by weight loss measurements. ER probe method was the most sensitive to corrosion and gave the most conservative estimation of the lifetime of copper. Independently whether the environment was abiotic or biotic, ER probe data showed relatively similar trends to the results from LPR and weight loss measurements. Difference in sensitivity of the methods arises from different ability to detect pitting corrosion and microbial activities on specimen surfaces in the two environments.
The corrosion rate of pure copper has been followed by thin electrical resistance (ER) sensors placed in a test package containing an oxic bentonite/saline groundwater environment at room temperature ...for a period of more than three years. Potential measurements have verified oxic conditions in the test package. A series of electrochemical impedance spectroscopy (EIS) measurements has also been performed on the ER sensors and results from one of the sensors are presented.
The impedance spectra for copper in the oxic bentonite/saline groundwater environment changed considerably with time of exposure. The impedance increased over the whole frequency range. Three methods were applied to estimate the corrosion rate from the EIS spectra.
The EIS measurements have revealed decreasing but measurable corrosion rates all through the exposure period. The former reveals a desired behaviour of copper in the environment. After three-year exposure the estimated corrosion rate from the EIS measurements fell in the range 0.4–0.7
μm/year, which is somewhat lower than the value of 1.0
μm/year, obtained from the ER measurements. Gravimetric data from six years exposure in the Äspö Hard Rock Laboratory showed an average corrosion rate of 0.5
μm/year. The corrosion resistance of copper is improved by the presence of bentonite.
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