SUMMARY REPORT ON POTENTIAL IMPACTS OF SMALL COLUMN ION EXCHANGE ON DWPF GLASS FORMULATION

Abstract

This report summarizes a large amount of experimental work completed to identify the potential impacts of material from Small Column Ion Exchange (SCIX) on glass formulation at the Defense Waste Processing Facility (DWPF). The results show no significant issues with the predicted values of chemical durability and viscosity using the current Product Composition Control System (PCCS) models when the SCIX components are added to projected DWPF glass compositions. No modifications to the viscosity and durability models appear to be necessary at this time in order to incorporate the SCIX streams at DWPF. It is recommended that the Savannah River National Laboratory (SRNL) continue to verify the durability and viscosity models as the projected compositions for DWPF processing evolve. It is also recommended that the data generated thus far be reviewed and a determination be made as to how best to extend the validation ranges of the durability and viscosity models. The liquidus temperatures for the experimental glasses are also reported and discussed in this report. The results show that the measured or estimated (based on measured data) liquidus temperature values for the glasses with SCIX components added are consistently higher than those predicted by the current model. Therefore, the PCCS liquidus temperature model will need to be modified in order to incorporate the SCIX streams at DWPF. It is recommended that SRNL carry out full measurements of the liquidus temperatures for those KT-series glasses where estimates have been made. These data should then be used to support an evaluation of whether a refitting of the liquidus temperature model coefficients will be sufficient to correctly predict the liquidus temperature of glasses containing the SCIX components (particularly higher TiO{sub 2} concentrations), or whether additional modifications to the model are required. While there are prediction issues with the current liquidus temperature model, they are not at this time expected to hamper the incorporation of SCIX streams at DWPF. The estimated liquidus temperatures, while higher than the model predicted values, remain below the current DWPF limit of 1050 C for most of the study glasses. Note that the properties and performance of the glasses in this study are highly dependent on glass composition. Therefore, should significant changes be made to the projected compositions or processing rates for SCIX or DWPF, many of the assessments and experiments may have to be revisited.