Title

Optimization of High-Level Waste Loading in a Borosilicate Glass Matrix by Using Chemical Durability Modeling Approach

Advisor

Ramsey, William G.

Committee Member

Toghiani, Rebecca K.

Committee Member

Toghiani, Hossein

Date of Degree

1-1-2002

Document Type

Graduate Thesis - Open Access

Major

Chemical Engineering

Degree Name

Master of Science

College

James Worth Bagley College of Engineering

Department

Department of Chemical Engineering

Abstract

A laboratory scale study was carried out on a set of 6 borosilicate waste glasses made from simulated high-level nuclear waste. The test matrix was designed to explore the composition region suitable for the long-term geologic disposal of high-temperature-and high-waste-containing glasses. The glass compositions were selected to achieve maximum waste loading without a sacrifice in glass durability. The relationship between glass composition and chemical durability was examined. The qualitative effect of increasing B2O3 content on the overall waste glass leaching behavior has also been addressed. The glass composition matrix was designed by systematically varying the factors: %waste loading and (SiO2+Frit):B2O3 ratio, with (SiO2:Frit) ratio being held constant. In order to assess the chemical durability, the Product Consistency Test (ASTM C-1285) was performed. Under PCT protocol, crushed glass was allowed to react with ASTM type I water under static conditions. All leachate solutions were analyzed by the technique; Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). A statistical regression technique was utilized to model the normalized release of the major soluble elements, Na, Si, and B, as a function of the individual as well as interactive chemical effects (B2O3, Al2O3, Fe2O3, MnO, SiO2, SrO, Na2O, B2O3*SiO2, B2O3*Al2O3, Fe2O3*Na2O, Al2O3*Na2O, and MnO*SiO2). Geochemical modeling was performed using the computer code EQ3/6 to: (1) determine the saturation states of the possible silicate minerals, a-cristobalite and chalcedony; and (2) predict the most stable mineral phase based on the mineral thermodynamic data. Mineral/water interactions were analyzed by representing the resultant glass data on a Na-Al-Si-O-H stability diagram.

URI

https://hdl.handle.net/11668/18940

Comments

Borosilicate Glass||Glass Structure||Glass Leaching||Thermodynamic Stability||Chemical Durability||Waste Loading

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