Effect of sulphide exposure on mechanical properties of CuOFP

In Finland and Sweden nuclear waste disposal is planned to be executed according to the KBS-3-concept. In the concept copper canisters containing the used nuclear fuel are buried in 400-500 m deep in the bedrock. Eventually the surface of the copper canister will come in contact with bentonite pore water which contains corrosive species such as sulphide. In this paper the effect of exposure to sulphide containing bentonite pore water at room temperature on the mechanical properties of oxygen free phosphorous doped copper (CuOFP) was studied with standard ex situ tensile and creep tests. Stress corrosion cracking (SCC) susceptibility of CuOFP was studied with in situ slow strain rate testing (SSRT). Tensile tests performed at room temperature showed a slight trend of degradation in mechanical properties with increasing sulphide concentration. Creep tests were accelerated by performing them at an elevated temperature of T = 215°C, but still within the power law creep regime. In creep tests the same kind of trend as in the tensile tests could be observed but when the results were compared to the publicly available CuOFP creep data the variations between the exposed and reference samples lay within the data scatter.