Model Matrices for Nuclear Waste Storage: Structure, Characterization, and Mechanical Properties

Glasses enriched with rare earth elements hold significant promise for nuclear waste storage, especially for immobilizing high- level waste (HLW) containing minor actinides. This chapter delves into the structural intricacies of peraluminous lanthanum- rich sodium aluminoborosilicate glasses, where lanthanum serves as a surrogate for lanthanides and minor actinides typical of HLW. Given the imperative to accommodate higher concentrations of HLW, the aluminum/boron substitution emerges as a pivotal factor influencing the glass matrix's properties. Employing a combination of infrared (IR), nuclear magnetic resonance (NMR), and Brillouin spectroscopy, we unravel the intricate interplay between composition and structure. Our investigation sheds light on the effects of aluminum/boron substitution on phase separation phenomena and structural rearrangements within the glass network. This in- depth analysis provides critical insights into the design and optimization of novel glass matrices tailored for advanced nuclear waste immobilization strategies.