Engineering topics

Fox, K. M.

Publications and source records attributed to Fox, K. M..

At least 19 records

DOE OSTI2019

Characterization of Hanford LAW Phase 3 Glasses

This report provides analyses of glass compositions, wash solution compositions, and Product Consistency Test (PCT) leachate compositions for a series of simulated low-activity waste (LAW) glasses fabricated at the Pacific Northwest National Laboratory (PNNL). These data will be used in the development of improved property/composition models for LAW glass at Hanford. Chemical analyses were performed on a representative sample of each of the quenched and sulfur saturated glasses to allow for comparisons with the targeted compositions. For some of the quenched glasses, measured concentrations of Cr 2 O 3 , K 2 O, Na 2 O, P 2 O 5 , and ZrO 2 were below the targeted values. For some of the sulfur saturated glasses, the measured concentrations of Al 2 O 3 , Cl - , Cr 2 O 3 , F - , K 2 O, Na 2 O, P 2 O 5 , V 2 O 5 , and ZrO 2 were generally low relative to the targeted values. A comparison of the measured compositions of the quenched and sulfur saturated versions of the study glasses showed that the measured concentrations of Al 2 O 3 , Cl - , and F - were lower for most of the sulfur saturated glasses. The measured Cr 2 O 3 and K 2 O concentrations were markedly lower for the sulfur saturated versions of the glasses as compared to the quenched versions, which may indicate that these elements partitioned to the soluble sulfur salts. A set of modified glasses was received from PNNL later in this study. Chemical analysis showed that these glasses generally met their targeted compositions. The measured SO 3 concentrations were higher for most of the sulfur saturated glasses relative to those of the quenched versions, as expected. Chemical analysis of the wash solutions that resulted from preparation of the sulfur saturated melts identified Cr, K, Na, P, S, and V as the major elements in solution. With the exception of sulfur, this may explain why the measured concentrations of these components in the study glasses were generally below the targeted values. PNNL performed PCTs on quenched and canister centerline cooled (CCC) versions of the study glasses, as well as the modified glasses. The leachates were sent to SRNL for chemical analysis. Minor scatter in the measured values among the triplicate samples for each glass was noted, with significant differences among the triplicate values noted for four of the CCC glasses. Normalized concentration values for some of the study glasses were greater than the 100 g/L maximum (total dissolution), which may indicate an error in the test. It is recommended that PNNL review the performance of the PCTs to determine the cause of these potential outliers and errors. Revision 1 of this report: Corrects an issue with high chromium measurements for the Mod glass compositions and the second set of PCT leachates, Adds data for the Mod glass wash solutions that were unintentionally omitted, Corrects an issue with rounding of the targeted Al 2 O 3 concentrations in the study glasses

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DOE OSTI2019

Supplemental Characterization of Hanford LAW Phase 2, Outer Layer Matrix Glasses

Supplemental chemical composition data are provided for a series of simulated low-activity waste glasses designated as the Phase 2, Outer Layer study. The glasses were selected and fabricated by the Pacific Northwest National Laboratory in support of property/composition model development for operation of the Hanford Tank Waste Treatment and Immobilization Plant. Additional characterization of glasses in this series is described in SRNL-STI-2018-00150, “Sulfur Solubility Testing and Characterization of Hanford LAW Phase 2, Outer Layer Matrix Glasses.” The measured concentrations of SO 3 reported here are generally lower than those measured for the earlier versions of these sulfur saturated glasses.

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DOE OSTI2019

Product Consistency Test Leachate Data for Nepheline Scoping Study Glasses

In this report, the Savannah River National Laboratory provides chemical analysis for a series of leachates resulting from Product Consistency Tests of nepheline study glasses performed at the Pacific Northwest National Laboratory. A review of the standard solution data identified no issues with the analytical methods. The results of this scoping study will be used as part of an effort to better understand nepheline crystallization in high-level nuclear waste glasses with high concentrations of aluminum and sodium.

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DOE OSTI2019

Chemical Composition Analysis and Product Consistency Tests of the ORP Phase 6 Nepheline Study Glasses

In this report, Savannah River National Laboratory (SRNL) provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated high-level waste (HLW) glass compositions fabricated at Pacific Northwest National Laboratory (PNNL). The results of this effort will improve the ability to predict the impacts of glass composition and nepheline crystallization on the durability of HLW glasses. Chemical analyses were performed on a representative sample of each of the quenched glasses to allow for comparisons with the targeted compositions. A review of the individual glass composition measurements identified no analytical issues of concern. Minor differences between the targeted and measured concentrations of some of the baseline glass components were noted, including some high values for Fe 2 O 3 , and some low values for Al 2 O 3 , Li 2 O, Na 2 O and P 2 O 5 . The PCT Method-A was performed in triplicate on each of the quenched and canister centerline cooled (CCC) versions of the glasses to assess chemical durability. A review of the leachate analyses and standard solution data identified no issues with the analytical methods. Some of the CCC versions of the study glasses have normalized concentration for boron (NC B ) values that are higher than the Environmental Assessment glass benchmark NC B value of 16.695 g/L. For some of the study glasses, the NC B values were higher after the CCC heat treatment. The normalized concentrations for lithium and sodium (NC Li and NC Na ) followed this same trend. For many of these glasses, the changes in the normalized concentration for silicon (NC Si ) values were not congruent with the changes in NC B , NC Li , and NC Na values. It may be valuable for PNNL to perform a more complete review of the influence of composition and heat treatment on the PCT responses of the glasses described in this report to draw further conclusions, including any potential correlations with the methods used in selecting these glass compositions for study.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Reduced Sample Masses for Characterization of Simulated Hanford Low-Activity Waste Glasses

In this report, a method for preparing a smaller mass of simulated low-activity waste glass for anion measurements is demonstrated. The required mass of sample was reduced from 1.0 g to 0.2 g. This method will be used in future studies to reduce the amount of time and effort needed to produce sulfur saturated glasses for characterization.

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DOE OSTI2018

Compositions of Simulated LAW Glasses Saturated with Sulfur at Various Temperature and Time Conditions

In this report, the Savannah River National Laboratory (SRNL) provides chemical analysis for several simulated low-activity waste (LAW) glass compositions, as well as chemical analysis of the wash solutions resulting from the preparation of these glasses. The Pacific Northwest National Laboratory (PNNL) selected and fabricated these glasses as part of a study on sulfur retention in glasses as a function of melting conditions.

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DOE OSTI2018

Sulfur Solubility Testing and Characterization of Hanford LAW Phase 2, Outer Layer Matrix Glasses

In this report, the Savannah River National Laboratory (SRNL) provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated Low-Activity Waste (LAW) glass compositions. A procedure developed at the Pacific Northwest National Laboratory (PNNL) for producing sulfur saturated melts (SSMs) was carried out at both SRNL and PNNL to fabricate the glasses characterized in this report. This method includes triplicate melting steps with excess sodium sulfate, followed by grinding and washing to remove unincorporated sulfur salts. The wash solutions were also analyzed as part of this study. These data will be used in the development of improved property/composition models for LAW glass.

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DOE OSTI2018

Sulfur Solubility Testing and Characterization of Hanford LAW Phase 2, Outer Layer Matrix Glasses

In this report, the Savannah River National Laboratory (SRNL) provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated Low-Activity Waste (LAW) glass compositions. A procedure developed at the Pacific Northwest National Laboratory (PNNL) for producing sulfur saturated melts (SSMs) was carried out at both SRNL and PNNL to fabricate the glasses characterized in this report. This method inclu des triplicate melting steps with excess sodium sulfate, followed by grinding and washing to remove unincorporated sulfur salts. The wash solutions were also analyzed as part of this study. These data will be used in the development of improved property/composition models for LAW glass.

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DOE OSTI2018

Measurements of Sulfur Concentration with Lower Detection Limits in Simulated LAW Glasses

This report provides sulfur concentration measurements for several simulated low-activity waste glass compositions. The Pacific Northwest National Laboratory (PNNL) selected and fabricated these glasses as part of a study on sulfur retention in glass. Methods were selected to achieve a lower detection limit for SO 3 than previously reported. The measured SO 3 concentrations of the glasses range from 0.036 to 0.130 wt %. These results will be used by PNNL in the development of improved property/composition models for LAW glass production at Hanford

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DOE OSTI2018

Visual Inspection of Defense Waste Processing Facility Melter 2 Interior after End of Service

Defense Waste Processing Facility (DWPF) Melter 2 reached its end of service life after nearly14 years. A visual inspection of the interior of the melter was performed using a remotely operated camera to provide insight into melter performance and potential failure mechanisms. The condition of the interior of the melter was generally good considering its relatively long service life. The plenum refractory appeared to be in good condition. Spalling and wear of the glass contact refractory was evident at the melt line. There appeared to be some degree of degradation and deposition of material at the dome heater penetrations. Deformation, or sagging of the dome heaters was visible. Only the top surfaces of the upper electrodes were visible due to the full inventory of glass remaining after melter shutdown. The electrodes exhibited small cracks as well as minor deformation (creep or slumping). The lower electrode failure mechanism could not be determined since it was not visible.

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DOE OSTI2018

Chemical Composition Analysis and Product Consistency Tests of the ORP Phase 5 Nepheline Study Glasses

In this report, the Savannah River National Laboratory (SRNL) provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated high-level waste glass compositions fabricated by the Pacific Northwest National Laboratory (PNNL). These data will be used in the development of improved models for the prediction of nepheline crystallization in support of the Hanford Tank Waste Treatment and Immobilization Plant (WTP).

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DOE OSTI2017

Characterization of the LAWB99-series and ORLEC-series Glasses

In this report, the Savannah River National Laboratory provides chemical analysis results for a series of simulated low activity waste (LAW) glass compositions. These data will be used in the development of improved sulfur solubility models for LAW glass. A procedure developed at the Pacific Northwest National Laboratory for producing sulfur saturated melts (SSMs) was used to fabricate the glasses characterized in this report. This method includes triplicate melting steps with excess sodium sulfate, followed by grinding and washing to remove unincorporated sulfur salts. The wash solutions were also analyzed as part of this study.

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DOE OSTI2017

Sulfur Solubility Testing and Characterization of Hanford LAW Phase 2, Inner Layer Matrix Glasses

In this report, the Savannah River National Laboratory (SRNL) provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated low activity waste (LAW) glass compositions. A procedure developed at the Pacific Northwest National Laboratory (PNNL) for producing sulfur saturated melts (SSMs) was carried out at both SRNL and PNNL to fabricate the glasses characterized in this report. This method includes triplicate melting steps with excess sodium sulfate, followed by grinding and washing to remove unincorporated sulfur salts. The wash solutions were also analyzed as part of this study. These data will be used in the development of improved sulfur solubility models for LAW glass.

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DOE OSTI2017

Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

The capacity of simulated high-level radioactive waste borosilicate glasses to incorporate sulfate has been studied as a function of glass composition. Combined Raman, 57 Fe Mössbauer and literature evidence supports the attribution of coordination numbers and oxidation states of constituent cations for the purposes of modelling, and results confirm the validity of correlating sulfate incorporation in multicomponent borosilicate radioactive waste glasses with different models. A strong compositional dependency is observed and this can be described by an inverse linear relationship between incorporated sulfate (mol% SO 4 2- ) and total cation field strength index of the glass, Σ(z/a 2 ), with a high goodness-of-fit (R 2 ≈ 0.950). Similar relationships are also obtained if theoretical optical basicity, Λ th (R 2 ≈ 0.930) or non-bridging oxygen per tetrahedron ratio, NBO/T (R 2 ≈ 0.919), are used. Results support the application of these models, and in particular Σ(z/a 2 ), as predictive tools to aid the development of new glass compositions with enhanced sulfate capacities.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Hanford enhanced waste glass characterization. Influence of composition on chemical durability

This report provides a review of the complete high-level waste (HLW) and low-activity waste (LAW) data sets for the glasses recently fabricated at Pacific Northwest National Laboratory and characterized at Savannah River National Laboratory (SRNL). The review is from the perspective of relating the chemical durability performance to the compositions of these study glasses, since the characterization work at SRNL focused on chemical analysis and ASTM Product Consistency Test (PCT) performance.

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DOE OSTI2016

Crystal accumulation in the Hanford Waste Treatment Plant high level waste melter. Preliminary settling and resuspension testing

The full-scale, room-temperature Hanford Tank Waste Treatment and Immobilization Plant (WTP) High-Level Waste (HLW) melter riser test system was successfully operated with silicone oil and magnetite particles at a loading of 0.1 vol %. Design and construction of the system and instrumentation, and the selection and preparation of simulant materials, are briefly reviewed. Three experiments were completed. A prototypic pour rate was maintained, based on the volumetric flow rate. Settling and accumulation of magnetite particles were observed at the bottom of the riser and along the bottom of the throat after each experiment. The height of the accumulated layer at the bottom of the riser, after the first pouring experiment, approximated the expected level given the solids loading of 0.1 vol %. More detailed observations of particle resuspension and settling were made during and after the third pouring experiment. The accumulated layer of particles at the bottom of the riser appeared to be unaffected after a pouring cycle of approximately 15 minutes at the prototypic flow rate. The accumulated layer of particles along the bottom of the throat was somewhat reduced after the same pouring cycle. Review of the time-lapse recording showed that some of the settling particles flow from the riser into the throat. This may result in a thicker than expected settled layer in the throat.

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DOE OSTI2016

Demonstration of sulfur solubility determinations in high waste loading, low-activity waste glasses

A method recommended by Pacific Northwest National Laboratory (PNNL) for sulfate solubility determinations in simulated low-activity waste glasses was demonstrated using three compositions from a recent Hanford high waste loading glass study. Sodium and sulfate concentrations in the glasses increased after each re-melting step. Visual observations of the glasses during the re-melting process reflected the changes in composition. The measured compositions showed that the glasses met the targeted values. The amount of SO 3 retained in the glasses after washing was relatively high, ranging from 1.6 to 2.6 weight percent (wt %). Measured SnO 2 concentrations were notably low in all of the study glasses. The composition of the wash solutions should be measured in future work to determine whether SnO 2 is present with the excess sulfate washed from the glass. Increases in batch size and the amount of sodium sulfate added did not have a measureable impact on the amount of sulfate retained in the glass, although this was tested for only a single glass composition. A batch size of 250 g and a sodium sulfate addition targeting 7 wt %, as recommended by PNNL, will be used in future experiments.

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DOE OSTI2016

Chemical analysis of simulated high level waste glasses to support stage III sulfate solubility modeling

The U.S. Department of Energy (DOE), Office of Environmental Management (EM) is sponsoring an international, collaborative project to develop a fundamental model for sulfate solubility in nuclear waste glass. The solubility of sulfate has a significant impact on the achievable waste loading for nuclear waste forms within the DOE complex. These wastes can contain relatively high concentrations of sulfate, which has low solubility in borosilicate glass. This is a significant issue for low-activity waste (LAW) glass and is projected to have a major impact on the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Sulfate solubility has also been a limiting factor for recent high level waste (HLW) sludge processed at the Savannah River Site (SRS) Defense Waste Processing Facility (DWPF). The low solubility of sulfate in glass, along with melter and off-gas corrosion constraints, dictate that the waste be blended with lower sulfate concentration waste sources or washed to remove sulfate prior to vitrification. The development of enhanced borosilicate glass compositions with improved sulfate solubility will allow for higher waste loadings and accelerate mission completion.The objective of the current scope being pursued by SHU is to mature the sulfate solubility model to the point where it can be used to guide glass composition development for DWPF and WTP, allowing for enhanced waste loadings and waste throughput at these facilities. A series of targeted glass compositions was selected to resolve data gaps in the model and is identified as Stage III. SHU fabricated these glasses and sent samples to SRNL for chemical composition analysis. SHU will use the resulting data to enhance the sulfate solubility model and resolve any deficiencies. In this report, SRNL provides chemical analyses for the Stage III, simulated HLW glasses fabricated by SHU in support of the sulfate solubility model development.

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