Glass Composition and Solution Speciation Effects
on the Dissolution Behavior of Nuclear Waste Glasses
EMSL Project ID
49157
Abstract
We are undertaking an investigation of the chemical and structural triggers of the dissolution behavior of nuclear waste glasses through a series of chemical and characterization studies covering a range of glass compositional space based primarily on two waste glass compositions (AFCI and SON68) that have been observed to exhibit very different behavior with respect to solution-phase alteration. It is our general hypothesis that solution speciation effects at high pH and near equilibrium conditions reach a tipping point that triggers a new stage of dissolution during the corrosion lifetime of these glasses. This point depends on the solution speciation generated by the glass and its environment, but filtered by transport of ions and water in and out of the altered surface layers. The primary chemical and structural features of these glass compositions that will be varied and characterized in detail include the Al/Si ratio, the relative concentrations of non-bridging oxygen (NBO) and charge neutralized aluminate and borate tetrahedra, and the presence and concentration of Li and Al. We propose that a series of solution-state and solid-state nuclear magnetic resonance (NMR) studies be run at EMSL of 6Li, 7Li, 10B, 11B, 23Na, 27Al, and 29Si nuclides in these glasses. These studies will provide local structural details that can be directly tied to the mechanisms and kinetics of glass dissolution and secondary phase precipitation, and ultimately to the qualification of candidate nuclear waste glasses for long-term remediation strategies.
Project Details
Start Date
2015-10-16
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator