Study of Variation in Reactive Surface Sites and Alteration Layer Properties of Nuclear Waste Glass Using Solid-State NMR

Open Access
Author:
Banks, Daniel Paul
Area of Honors:
Chemistry
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Karl Todd Mueller, Thesis Supervisor
  • Raymond Lee Funk, Honors Advisor
Keywords:
  • NMR
  • nuclear
  • waste
  • glass
  • solid
  • state
  • chemistry
  • corrosion
  • magnetic
  • resonance
  • surface
Abstract:
The incorporation of nuclear waste materials into borosilicate glasses through the process of vitrification has been studied as a method for storing the harmful radioactive waste products produced from nuclear fuel processing. Borosilicate glasses are an ideal choice for the storage of nuclear waste materials due to their high chemical and thermal stability over the radioactive lifetime of the waste components. One of the primary concerns involving nuclear waste vitrification is the corrosion of these glasses in the presence of water. The focus of this study is to measure the chemical reactivity of these waste glass surfaces under different corrosion conditions such as pH, corrosion time, surface area, and glass composition. We quantify the chemical reactivity of these surfaces by measuring the number of lone Q3 surface hydroxyls via attachment of the probe molecule 3,3,3-(trifluoropropyldimethyl)chlorosilane (TFS) and 19F magic-angle spinning solid-state NMR analysis. The glass samples examined in this study were the simulated waste glasses SA1R and SS2R which are modeled after the American AFCI and French SON68 waste glasses respectively. The results of our study show that the surface reactivity of these waste glasses depends on a number of different factors. We find that the chemical reactivity of these glasses increases as a function of increasing surface area and pH. We also observe a variation in the number of measured reactive surface sites as a function of increasing corrosion time. From the results of our study we also hypothesize that there are interactions occurring between the buffer components used in our corrosion solutions and the surface of our glass samples. If this is the case it may be possible that these buffer components used in glass corrosion experiments may block corrosion sites. However, further studies would need to be performed in order to confirm this hypothesis.