WIPP/SRL in situ tests: Part 3, Compositional correlations of MIIT (Materials Interface Interactions Test) waste glasses

The Materials Interface Interactions Test (MIIT) is the only in situ program involving the burial of simulated high-level wasteforms that is operating in the United States. Fifteen glass and wasteform compositions and their proposed package materials, supplied by seven countries, are interred in salt at the Waste Isolation Pilot (WIPP) in Carlsbad, New Mexico. A joint effort between Sandia National Laboratories and Savannah River Laboratory, MIIT is the largest and most internationally cooperative in situ venture yet undertaken. The objective of the current study is to document the wasteform compositions used in the MIIT program and then to examine compositional correlations based on structural considerations, bonding energies, and surface-layer formation. These correlations show important similarities between the many different waste glass compositions studied worldwide and suggest that these glasses would be expected to perform well and in a similar manner. The compositional correlations define a commonality between all MIIT wasteforms and assist in furthering our understanding of high-level waste glass performance. 16 refs., 12 figs., 2 tabs.