Crevice corrosion of copper as an engineering barrier of high-level radioactive waste containers

摘要

This work is aimed at determining the viability of oxygen-free copper as an engineering barrier of high-level radioactive waste containers. This material stands out because of its excellent resistance to generalized and localized corrosion in aqueous electrolytes; particularly in reducing environments as the ones expected in repository sites located below the water table. As the first part of a more general analysis, the corrosive effects of different ions potentially in contact with the barrier were studied. Eight systems with different concentrations of chloride, sulfate and bicarbonate (0.001 to 1 M) and different temperatures (30 to 90 °C) were selected. Open circuit potential tests and Potentiodynamic-Galvanostatic-Potentiodynamic tests were performed to determine the existence of crevice corrosion. Artificial crevice formers were used. Scanning electron microscopy and optical microscopy were used to characterize the creviced specimens after testing. Corrosion products composition was determined by Energy Dispersive Microanalysis. The crevice corrosion tests showed that crevice corrosion is observed only in some of the 8 selected solutions. The corrosion was not very deep and it occurred below the edges of the crevice formers. Some corrosion was observed out of the crevices, in the bulk zone, indicating the possible occurrence of inverse crevice corrosion.