Dissertation
Structure of Glasses and Glass-forming Liquids with Application to Nuclear Waste Vitrification
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/112033
Abstract
Phase separation during the vitrification of nuclear waste can be detrimental to the processing of nuclear waste as well as the long-term chemical durability of the glassy waste form. In Hanford Low Activity Waste, phase separation due to the formation of a molten salt phase during batch-to-glass conversion can decrease the lifetime of the Joule-heated ceramic melters as well as form a water-soluble crystalline salt phase on cooling. In Hanford High-Level Waste, the high-Na and high-Al contents can promote crystallization of nepheline, and related phases, on cooling from melt, which decreases the long-term chemical durability of the glass. This study seeks to understand these examples of phase separation in simplified compositions through structural analysis of the melt, glass, and resulting crystalline phases. In the simplified Low Activity Waste composition studies, the structures of mixed halide-sulfate systems are analyzed and related to the structure of traditional glass-forming materials. In the simplified High-Level Waste composition studies, melts and glasses related to the nominal nepheline composition (NaAlSiO4) are of interest for structure-crystallization relationships. The structure of these materials has been probed through X-ray and neutron total scattering and was supplemented with atomistic simulation, Raman spectroscopy, X-ray absorption spectroscopy, and other methods. Implications for phase separation in these materials are drawn based upon the local environments of oxyanions in the salt-based materials and dopant species in the nepheline-based compositions.
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Details
- Title
- Structure of Glasses and Glass-forming Liquids with Application to Nuclear Waste Vitrification
- Creators
- Emily Taapke Nienhuis
- Contributors
- John S. McCloy (Advisor)Aurora Clark (Committee Member)Min-Kyu Song (Committee Member)Di Wu (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Materials Science and Engineering Program
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 323
- Identifiers
- 99900581702901842
- Language
- English
- Resource Type
- Dissertation