This report is a modified version of WSRC-TR-2001-00124, Revision 0. Information related to the chemical compositions of the study glasses has been removed from this version. WSRC has submitted a patent application for the frit (designated as BD1) utilized in the study and is limiting the distribution of the details of the compositions of the study glasses to protect its intellectual property rights pending patent clearance.
This study was conducted to determine the effect, if any, on the PCT responses of glasses cooled at different rates. Two bounding cooling profiles were used in this study: rapidly quenched and a canister centerline cooling curve. Glasses were selected based on a number of criteria, but mainly to challenge the regions where amorphous phase separation is expected based upon current model predictions. The current DWPF homogeneity constraint, imposed to preclude regions of phase separation, predicted that most of the glasses selected would be phase separated. It was, therefore, important to ensure that deleterious phase separation does not occur at either cooling profile. In this case, deleterious phase separation is defined as the formation of an amorphous phase in the glass that significantly decreases the glass durability as measured by the PCT response.
The U.S. Department of Energy (DOE) is nearing a decision on how to process 30 million gallons of high-level radioactive waste salt solutions at the Savannah River Site in South Carolina to remove strontium, actinides, and cesium for immobilization in glass and eventual shipment to a geologic repository. The department is sponsoring research and development (R&D) work on four alternative processes and plans to use the results to make a downselection decision in a June 2001 time frame. The DOE requested that the National Research Council help inform this decision by addressing the following charge: evaluate the adequacy of the criteria that will be used by the department to select from among the candidate processes under consideration; evaluate the progress and results of the research and development work that is being undertaken on these candidate processes; and assess whether the technical uncertainties have been sufficiently resolved to proceed with downsizing the list of candidate processes. Responses to the last two points are provided in this report. Research and Development on a Salt Processing Alternative for High-Level Waste at the Savannah River Site focuses exclusively on the technical issues related to the candidate processes for radionuclide removal from high-level waste salt solutions at SRS. The committee's interim report served as a response to the first point of this charge, and may be read in Appendix B. In that report, the committee found that DOE's proposed criteria are an acceptable basis for selecting among the candidate processes under consideration, but that the criteria should not be implemented in a way that relies on a single numerical "total score."
When waste glass is poured into metal canisters, it fractures, primarily due to temperature gradients induced during cooling. A technique to quantitatively determine the additional glass surface area due to fracture was developed based on this study.
This report provides a summary of the results obtained for a limited variability study for glasses containing Crystalline Silicotitanate (CST), Monosodium Titanate (MST), and either simulated Purex or HM sludge. Twenty-two glasses containing Purex sludge and three glasses containing HM sludge were fabricated and tested. The fabricated glasses were tested for durability using the 7-day Product Consistency Test (PCT) and characterized by measuring the viscosity at 1,150 C and by determining an approximate, bounding liquidus temperature. The current models used by Defense Waste Processing Facility (DWPF) for predicting durability, viscosity, and liquidus temperature were applied to all 25 glasses. The goal of this work was to identify any major problems from a glass perspective, within the scope of this effort, which could potentially preclude the use of CST at DWPF.
On cover: Reclamation, Managing Water in the West. Describes how transformers work, how they are maintained, and how to test and evaluate their condition.
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