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Sulfur solubility and Monofrax™ K-3 refractory corrosion in simplified borosilicate-based nuclear waste glasses
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Xu, Xinyi. Sulfur solubility and Monofrax™ K-3 refractory corrosion in simplified borosilicate-based nuclear waste glasses. Retrieved from https://doi.org/doi:10.7282/t3-15dq-0p28

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TitleSulfur solubility and Monofrax™ K-3 refractory corrosion in simplified borosilicate-based nuclear waste glasses
NameXu, Xinyi (author); Goel, Ashutosh (chair); Goel, Ashutosh (member); Klein, Lisa (member); Safari, Ahmad (member); McCloy, John S (member); Youngman, Randall E (member); Rutgers University; School of Graduate Studies
Date Created2022
Other Date2022-10 (degree)
SubjectMaterials Science, Melt chemistry, Nuclear waste glasses, Refractory corrosion, Structure, Sulfur solubility
Extent1 online resource (284 pages) : illustrations
DescriptionThe United States department of energy (DOE) is planning for the implementation of direct feed approach, which is expected to pose two main challenges during the nuclear waste vitrification process, the sulfate salt layer formation on melt surface and the Monofrax™ K-3 refractory corrosion. Both are potentially detrimental to the long-term operation of the Joule heated ceramic melter (JHCM). Currently, most of our scientific understanding of both subjects are limited to cause-effect relationship, and cannot account for waste glasses with higher compositional complex brought by the direct-feed approach. Thus, the overarching goal of this research is to gain a deeper insight into the structural drivers and underlying mechanisms governing the solubility of sulfur in the borosilicate- based nuclear waste glasses; and to unearth the corrosion behavior of K-3 refractory as a function of glass chemistry.

A set of studies are being taken in Na₂O-Al₂O₃-B₂O₃-SiO₂ system to systematically investigate the sulfate solubility as a function of the short-to-medium range structural ordering. And it is found that, the network polymerization degree and cationic field strength scale negatively with sulfur loading limit in the host glasses. Furthermore, the studies are focused on investigating the underlying structural transformations caused by Fe₂O₃, and Cr₂O₃ in borosilicate-based glass systems and their impact on sulfur solubility. The strengths of spectroscopic techniques, including Mossbauer, Raman and ICP-OES spectroscopies, and MD simulations are combined to obtain an in-depth understanding of the short- and intermediate-range structural features in the Fe-doped aluminoborosilicate glasses. The reduction of the available Na⁺ at NBO sites at the presence of tetrahedral Fe³⁺ is considered as the main reason suppressing the incorporation of sulfur in the glass structure. Cr redox speciation and their corresponding local environments in sodium borosilicate glasses are studied by the UV-Vis and EPR spectroscopy. A redox shift from Cr³⁺ to Cr⁶⁺ is favored with the sulfur addition, which exacerbates the competition between chromate (CrO₄²⁻) and sulfate (SO₄²⁻) for fixed Na⁺ and available space in glass matrix, and further lowers the sulfur solubility.

Lastly, corrosion tests aimed to investigated the corrosion impact of glass network formers, i.e. SiO₂, B₂O₃ and Al₂O₃, on the Monofrax™ K-3 refractory is conducted in accordance with the ASTM C621. The chemical interactions at the melt-refractory interface have been followed using SEM-EDS, XRD, and ICP-OES. According to the elemental diffusion profiles across the glass–refractory interface, a description of the refractory corrosion mechanism is proposed.
NotePh.D.
NoteIncludes bibliographical references
Genretheses
Persistent URLhttps://doi.org/doi:10.7282/t3-15dq-0p28
LanguageEnglish
CollectionSchool of Graduate Studies Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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