Abstract
Alloy 22 (N06022) is the candidate material for the corrosion resistant, outer barrier of the nuclear waste container. Two of the potential corrosion degradation modes of the container are uniform corrosion and localized corrosion. A testing program at the Lawrence Livermore National Laboratory is being carried out for Yucca Mountain to determine the susceptibility of Alloy 22 to these two forms of corrosion using long-term immersion tests. Metallic coupons were exposed to several electrolyte solutions simulating concentrated ground water from pH 3 to 10 at 60°C and 90°C. This paper summarizes results on the characteristics of the surface deposits as well as the corrosion rate of 122 coupons of Alloy 22 obtained after more than a five-year exposure. The surface deposits consisted primarily of salt components in the respective solutions. Results showed little general corrosion and the absence of localized (crevice) corrosion.