The current design of the waste disposal containers relies heavily on encasement in a multi-layered container, featuring a corrosion barrier of Alloy 22, a Ni-Cr-Mo-W based alloy with excellent corrosion resistance over a wide range of conditions. The fundamental concern from the perspective of the Yucca Mountain Project, however, is the inherent uncertainty in the (very) long-term stability of the base metal and welds. Should the properties of the selected materials change over the long service life of the waste packages, it is conceivable that the desired performance characteristics (such as corrosion reistance) will become compromised, leading to premature failure of the system. To address this, we will study the phase stability and solute segregation characteristics of Alloy 22 base metal and welds. A better understanding of the underlying microstructural evolution tendencies, and their connections with corrosion behavior will (in turn) produce a higher confidence in the extrapolated behavior of the container materials over time periods that are not feasibly tested in a laboratory. Additionally, the knowledge gained here may potentially lead to cost savings through development of safe and realistic design constraints and model assumptions throughout the entire disposal system.
Geological repositories; Nevada – Yucca Mountain; Nickel-chromium alloys; Radioactive waste canisters; Radioactive waste repositories
Mechanics of Materials | Metallurgy | Nuclear Engineering
Namjoshi, S. A.,
Keeler, R. E.,
Smiecinski, A. J.
Phase Stability and Segregation in Alloy 22 Base Metal and Weldments.
Available at: http://digitalscholarship.unlv.edu/yucca_mtn_pubs/113