Effect of sulfide ions regarding to resistance to corrosion of cooper for used in manufacturing of containers for high level radioactive waste (HLW)

We have studying the effect of sulfide ions regarding to resistance to corrosion of copper UNS C10100 doped with 50 ppm of phosphorous (Cu-OFP), at the temperature of 25oC. This material is a candidate to be used for high level radioactive waste containers in Sweden. The electrolyte is a synthetic water whose composition is similar to groundwater composition, that it's suppose will run through nuclear repository where containers would be buried. Also in the literature we can find studies regarding to effect of sulphides ion on copper (13, 14, 15), but in present work we will intent only consider the effect of sulphides simulating the composition of the groundwater in the repository. The average pH is 9.3 and sulphide present is approximately 1 ppm. Also chloride is another potential corrodant, but in deep repositories whose groundwaters are neutral or slightly alkaline, the effect of chlorides can be neglected. The electrochemical cell consist of three electrodes: work electrode (copper), counter electrode (platinum 99.97%) and reference electrode (calomel). The working methodology were potentiodynamic test such as cyclic voltammetry and anodic polarization test and also potentiostatic test. The characterization test performed were scanning electronic microscopy, X-ray photoelectronic spectroscopy and X-ray diffraction. The equipment used for these experiments was a Princeton Applied Research Potentiostat/Galvanostat Model 273-A coupled to a computer data-acquisition system. It is possible determine that the effect of sulphide ion produce on corrosion copper resistance, at level of 1 ppm, is micropitting. The presence of anions as HCO-3- at environments conditions produce a benefit effect because this ion has inhibitor effect of this micropitting