Investigating the Effect of Glass Ion Release on the Cytocompatibility, Antibacterial Eflcacy and Antioxidant Activity of Y2O3 / CeO2 doped SiO2-SrO-Na2O glasses

The effect on ion release and cytocompatibility of Yttrium (Y) and Cerium (Ce) are investigated when substituted for Sodium (Na) in a 0.52SiO2-0.24SrO-0.24-Na2OMOglass series (where MO= Y2O3or CeO2). Glass leaching was evaluated through pH measurements and Inductive Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysiswhere the extract pH increased during incubation (11.2 - 12.5). Ion release of Silicon (Si), Na and Strontium (Sr) from the Con glass was at higher than that of glasses containing Y or Ce, and reached a limit after 1 day. Ion release from Y and Ce containing glasses reached a maximum of 1800 μg/mL, 1800 μg/mL, and 10 μg/mL for Si, Na, and Sr, respectively. Release of Y and Cewas below the ICP- OES detection limit <0.1 μg/mL. Cell viability of both L929 fibroblasts and MC3T3 osteoblasts decreased for Con, LY, and LCe extracts; HY extracts did not significantly decrease cell viability while YCe and HCe saw concentrationdependent viability decrease (20%, 33% extract concentrations). Bacterial studies saw Con and LCe eliminating >75% of bacteria at a 9% extract concentration. Antioxidant capacity (mechanism for neuroprotection) was evaluated using the ABTS assay. All glasses had inherent radical oxygen species (ROS) scavenging capability with Con reaching 9.5 mMTE.

Single Idealized Cracks: A Tool for Understanding Fractured Glass Block Leaching

Within the scope of the long term behaviour of the R7T7 glass, which is the French nuclear glass, leaching and its coupling with transport mechanisms is studied. Experiments carried out on a SON 68 glass (inactive R7T7 type glass) model cracks in static basic conditions show a strong coupling between solution transport and glass leaching, depending on crack aperture. Moreover, gravity driven convective transport was evidenced for vertical model cracks, whereas only molecular diffusion was detected for horizontal model cracks under the same alteration conditions. In addition, an original device was developed to study the influence of temperature gradients on alteration kinetics as a convective driving force. These experiments show conclusively that thermally- or gravity-induced convective flow must be taken into account, even if such convective effects have not been established experimentally in neutral condition, which is more realistic condition for geological storage. A modeling, based on a porous geochemical software (HYTEC) accounting for both chemistry and transport, has been successfully applied to describe alteration within simple silicate glass cracks. It will be extended to study SON 68 glass model cracks, and more complex fracture networks.

Study of simulated HLW-glass leaching behavior under low oxygen repository condition

ABSTRACTMany countries have recognized vitrification as the suitable solidification method for conditioning high level radioactive waste before they are isolated from biosphere in geologic disposal. This paper studies the leaching behavior of a simulated HLW-glass (90Nd/10) under low oxygen repository condition during 1.5 years. The leaching results showed that the glass was corroded less under low oxygen condition than under ambient atmosphere. XRD analyses showed some little diffraction peak appeared on the leached glass surface at 150°C. At the same time, no diffraction peak appeared on the leached glass surface at 90°C. The secondary products formed on the surface of the leached glass contained mainly Si, Al, Ca and Fe.