Containment of spent nuclear fuel and vitrified forms of high level nuclear waste require use of materials that are highly corrosion resistant to all of the anticipated environmental scenarios that can occur in a geological repository. Ni-Cr-Mo Alloy 22 (UNS N60622) is proposed for the corrosion resistant outer barrier of a two-layer waste package container at the potential repository site at Yucca Mountain. A range of water compositions that may contact the outer barrier is under consideration, and a testing program is underway to characterize the forms of corrosion and to quantify the corrosion rates. Results from the testing support models for long term prediction of the performance of the container. Results obtained to date indicate a very low general corrosion rate for Alloy 22 and very high resistance to all forms of localized and
environmentally assisted cracking in environments tested to date.
Keywords: high level nuclear waste, Ni-Cr-Mo alloys, N06022, Yucca Mountain, J-13 well water, titanium, corrosion resistant alloys, general corrosion, localized corrosion, stress corrosion cracking, microbiologically influenced corrosion, physical metallurgy, process metallurgy