Long-Term Corrosion Behavior of Copper-Base Materials in a Gamma-Irradiated Environment

Abstract

AbstractThe U. S. Department of Energy is currently evaluating the feasibility of using copper-base materials for the manufacture of nuclear waste con- tainers. One site under consideration for geologic disposal of nuclear waste is at Yucca Mountain, Nevada. One feature of this waste repository will be the initial presence of ionizing gamma radiation at high dose rates, which may alter the corrosive medium. To evaluate such effects, three copper-base materials (pure copper, 7% aluminum-copper and 30% nickel-copper) have been exposed (presgntly up to 14 months) to a gamma radiation field of approxi- mately 1 × 104 roentgens/hr. The exposure environments have been: 1) both groundwater (regional to the repository site, although taken from a lower elevation) at 95°C; 2) the water-vapor saturated air phase above it; and 3) air/water vapor at 150°C. In addition to uniform corrosion, both pitting and crevice corrosion have been observed. Characterization of the corrosion layers by X-ray diffraction has shown the presence of mixed copper(I) and copper(II) oxides. Studies by Auger Electron Spectroscopy (AES) have also been conducted in order to further characterize the compositions and structures of these corrosion products.