The Savannah River National Laboratory is collaborating with Alfred University to evaluate the potential for additives in borosilicate glass to improve sulfur retention. This preliminary report provides further background on the incorporation of sulfur in glass and outlines the experiments that are being performed by the collaborators. A simulated waste glass composition has been selected for the experimental studies. The first phase of experimental work will evaluate the impacts of BaO, PbO, and V 2 O 5 at concentrations of 1.0, 2.0, and 5.0 wt % on sulfate retention in simulated high level waste borosilicate glass. The second phase of experimental work will evaluate the effects of time at the melt temperature on sulfur retention. The resulting samples will be characterized to determine the amount of sulfur remaining as well as to identify the formation of any crystalline phases. The results will be used to guide the future selection of frits and glass forming chemicals in vitrifying Department of Energy wastes containing high sulfur concentrations.
SRNL-STI-2011-00524Revision 0 vi
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IntroductionSulfur has a low solubility in borosilicate glasses. This presents a significant challenge to the U.S. Department of Energy (DOE) immobilization campaigns for wastes with high sulfur concentrations since borosilicate glass is being used to vitrify high level radioactive waste (HLW) at the Savannah River Site (SRS) and is planned for use in vitrifying wastes at Hanford. A more thorough understanding of the incorporation of sulfur in the borosilicate glass network (and the issues that hinder its incorporation) could lead to improvements in sulfur retention, allowing for a higher level of waste loading in the glass.The Savannah River National Laboratory (SRNL) is collaborating with Alfred University (AU) to evaluate the potential for additives in the borosilicate glass frit or glass forming chemicals to improve sulfur retention. This preliminary report provides further background on the incorporation of sulfur in glass and outlines the experiments that will be performed by the collaborators. AU has completed a survey of relevant literature and provided recommendations for the experimental work. That document is included as Appendix A. The experimental work will be performed using simulated, non-radioactive glasses, with the intent of identifying modifications that can be made to the frit compositions recommended for future operation of the Defense Waste Processing Facility (DWPF) at SRS for improved sulfur retention.
SRNL-STI-2011-00524Revision 0 2
Evaluation of Frit AdditivesCollaborators at AU have recommended that three frit additives, BaO, PbO, and V 2 O 5 , be evaluated for potential improvements in sulfate retention. Batching, melting, and some characterization of test glasses for this phase of the experimental work will be completed by AU. The recommended additives will be added in concentrations of 1.0, 2.0, and 5.0 wt %. The concentrations of the frit components in the glass will be reduced propo...