Durability And Nepheline Crystallization Study For High Level Waste Hlw Sludge Batch 4 Sb4 Glasses Formulated With Frit 503

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DURABILITY AND NEPHELINE CRYSTALLIZATION STUDY FOR HIGH LEVEL WASTE (HLW) SLUDGE BATCH 4 (SB4) GLASSES FORMULATED WITH FRIT 503

Author : T. Tommy Edwards
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis DURABILITY AND NEPHELINE CRYSTALLIZATION STUDY FOR HIGH LEVEL WASTE (HLW) SLUDGE BATCH 4 (SB4) GLASSES FORMULATED WITH FRIT 503 by : T. Tommy Edwards

Download or read book DURABILITY AND NEPHELINE CRYSTALLIZATION STUDY FOR HIGH LEVEL WASTE (HLW) SLUDGE BATCH 4 (SB4) GLASSES FORMULATED WITH FRIT 503 written by T. Tommy Edwards and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Defense Waste Processing Facility (DWPF) is about to process High Level Waste (HLW) Sludge Batch 4 (SB4). This sludge batch is high in alumina and nepheline can crystallize readily depending on the glass composition. Large concentrations of crystallized nepheline can have an adverse effect on HLW glass durability. Several studies have been performed to study the potential for nepheline formation in SB4. The Phase 3 Nepheline Formation study of SB4 glasses examined sixteen different glasses made with four different frits. Melt rate experiments were performed by the Process Science and Engineering Section (PS & E) of the Savannah River National Laboratory (SRNL) using the four frits from the Phase 3 work, plus additional high B2O3/high Fe2O3 frits. Preliminary results from these tests showed the potential for significant improvements in melt rate for SB4 glasses using a higher B2O3-containing frit, particularly Frit 503. The main objective of this study was to investigate the durability of SB4 glasses produced with a high B2O3 frit likely to be recommended for SB4 processing. In addition, a range of waste loadings (WLs) was selected to continue to assess the effectiveness of a nepheline discriminator in predicting concentrations of nepheline crystallization that would be sufficient to influence the durability response of the glass. Five glasses were selected for this study, covering a WL range of 30 to 50 wt% in 5 wt% increments. The Frit 503 glasses were batched and melted. Specimens of each glass were heat-treated to simulate cooling along the centerline of a DWPF-type canister (ccc) to gauge the effects of thermal history on product performance. Visual observations on both quenched and ccc glasses were documented. A representative sample from each glass was submitted to the SRNL Process Science Analytical Laboratory (PSAL) for chemical analysis to confirm that the as-fabricated glasses corresponded to the defined target compositions. The Product Consistency Test (PCT, ASTM C1285) was performed in triplicate on each Frit 503 quenched and ccc glass to assess chemical durability. The experimental test matrix also included the Environmental Assessment (EA) glass and the Approved Reference Material (ARM-1) glass. Representative samples of all the ccc glasses were examined for homogeneity visually and by X-ray diffraction (XRD) analysis. Chemical composition measurements indicated that the experimental glasses were close to their target compositions. PCT results showed that all of the Fit 503 quenched glasses had an acceptable durability compared to the EA benchmark glass. The durability of one of the ccc glasses, NEPHB-04, was statistically greater than its quenched counterpart. However, this was shown to be of little practical significance, as the durability of the NEPHB-04 ccc glass was acceptable when compared to the durability of the EA benchmark glass. Visual observations and PCT results indicated that all of the Frit 503 quenched glasses were free of any crystallization that impacts durability. For the ccc glasses, XRD results indicated that the lower WL glasses (30 to 40 wt%) were amorphous, which was consistent with visual observations and PCT responses. The higher WL glasses (45 and 50 wt%) were shown by XRD to contain spinel (trevorite, NiFe2O4). It is possible that some of the other high WL glasses also contained some nepheline, but that the amount of nepheline crystallization was below the detection limit (0.5 vol%) associated with XRD. The results indicate that Frit 503 is a good candidate for SB4 processing, based on chemical durability of homogeneous and devitrified glasses over a WL range of 30 - 50%. It should be noted that the higher WL glasses would not be fit for processing in DWPF as they exceed other process related criteria (such as liquidus temperature). However, this is only one of many factors influencing the frit selection. Melt rate and the final SB4 composition are also important factors in frit selection. Additional melt rate studies are currently underway, and the final composition projection for SB4 is expected shortly.

Environmental Issues and Waste Management Technologies in the Materials and Nuclear Industries XII

Author : Alex Cozzi
Publisher : John Wiley & Sons
ISBN 13 : 0470538368
Total Pages : 322 pages
Book Rating : 4.4/5 (75 download)

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Book Synopsis Environmental Issues and Waste Management Technologies in the Materials and Nuclear Industries XII by : Alex Cozzi

Download or read book Environmental Issues and Waste Management Technologies in the Materials and Nuclear Industries XII written by Alex Cozzi and published by John Wiley & Sons. This book was released on 2009-09-24 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book documents a special collection of articles from a select group of invited prominent scientists from academia, national laboratories and industry who presented their work at the symposia on Environmental and Energy Issues at the 2008 Materials Science and Technology (MS&T’08) conference held in Pittsburgh, PA. These articles represent a summary of the presentations focusing on topics in nuclear, environmental, and green engineering were held, including a discussion of Waste Glass Leach Testing and Modeling.

Advances in Materials Science for Environmental and Nuclear Technology

Author : Kevin M. Fox
Publisher : John Wiley & Sons
ISBN 13 : 0470930977
Total Pages : 312 pages
Book Rating : 4.4/5 (79 download)

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Book Synopsis Advances in Materials Science for Environmental and Nuclear Technology by : Kevin M. Fox

Download or read book Advances in Materials Science for Environmental and Nuclear Technology written by Kevin M. Fox and published by John Wiley & Sons. This book was released on 2010-10-01 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Materials Science and Technology 2009 Conference and Exhibition (MS&T’09) was held October 25-29, 2009, in Pittsburgh, Pennsylvania. A major theme of the conference was Environmental and Energy Issues. Papers from three of the symposia held under that theme are included in this volume. These symposia include Materials Solutions for the Nuclear Renaissance; Green Engineering and Environmental Stewardship; and Nanotechnology for Energy. These symposia included a variety of presentations with sessions focused on sustainable energy, photovoltaics, nanowires and composites, energy harvesting, catalysts, thin films, corrosion, nuclear fuels, materials in aggressive environments, glass and ceramics for waste disposition, modeling and thermal properties, and education. Also included was a series of invited presentations and an international panel discussion on cement waste forms. The Green Engineering and Environmental Stewardship symposium was sponsored by the Nuclear and Environmental Technology Division (NETD) of The American Ceramic Society while the Materials Solutions for the Nuclear Renaissance symposium was sponsored by NETD and ASM International.

PERMEABILITY, SOLUBILITY AND DIFFUSIVITY OF HYDROGEN ISOTOPES IN STAINLESS STEELS AT HIGH GAS PRESSURES.

Author : K. Subramanian
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis PERMEABILITY, SOLUBILITY AND DIFFUSIVITY OF HYDROGEN ISOTOPES IN STAINLESS STEELS AT HIGH GAS PRESSURES. by : K. Subramanian

Download or read book PERMEABILITY, SOLUBILITY AND DIFFUSIVITY OF HYDROGEN ISOTOPES IN STAINLESS STEELS AT HIGH GAS PRESSURES. written by K. Subramanian and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Defense Waste Processing Facility (DWPF) is about to process High Level Waste (HLW) Sludge Batch 4 (SB4). This sludge batch is high in alumina and nepheline can crystallize readily depending on the glass composition. Large concentrations of crystallized nepheline can have an adverse effect on HLW glass durability. Several studies have been performed to study the potential for nepheline formation in SB4. The Phase 3 Nepheline Formation study of SB4 glasses examined sixteen different glasses made with four different frits. Melt rate experiments were performed by the Process Science and Engineering Section (PS & E) of the Savannah River National Laboratory (SRNL) using the four frits from the Phase 3 work, plus additional high B2O3/high Fe2O3 frits. Preliminary results from these tests showed the potential for significant improvements in melt rate for SB4 glasses using a higher B2O3-containing frit, particularly Frit 503. The main objective of this study was to investigate the durability of SB4 glasses produced with a high B2O3 frit likely to be recommended for SB4 processing. In addition, a range of waste loadings (WLs) was selected to continue to assess the effectiveness of a nepheline discriminator in predicting concentrations of nepheline crystallization that would be sufficient to influence the durability response of the glass. Five glasses were selected for this study, covering a WL range of 30 to 50 wt% in 5 wt% increments. The Frit 503 glasses were batched and melted. Specimens of each glass were heat-treated to simulate cooling along the centerline of a DWPF-type canister (ccc) to gauge the effects of thermal history on product performance. Visual observations on both quenched and ccc glasses were documented. A representative sample from each glass was submitted to the SRNL Process Science Analytical Laboratory (PSAL) for chemical analysis to confirm that the as-fabricated glasses corresponded to the defined target compositions. The Product Consistency Test (PCT, ASTM C1285) was performed in triplicate on each Frit 503 quenched and ccc glass to assess chemical durability. The experimental test matrix also included the Environmental Assessment (EA) glass and the Approved Reference Material (ARM-1) glass. Representative samples of all the ccc glasses were examined for homogeneity visually and by X-ray diffraction (XRD) analysis. Chemical composition measurements indicated that the experimental glasses were close to their target compositions. PCT results showed that all of the Fit 503 quenched glasses had an acceptable durability compared to the EA benchmark glass. The durability of one of the ccc glasses, NEPHB-04, was statistically greater than its quenched counterpart. However, this was shown to be of little practical significance, as the durability of the NEPHB-04 ccc glass was acceptable when compared to the durability of the EA benchmark glass. Visual observations and PCT results indicated that all of the Frit 503 quenched glasses were free of any crystallization that impacts durability. For the ccc glasses, XRD results indicated that the lower WL glasses (30 to 40 wt%) were amorphous, which was consistent with visual observations and PCT responses. The higher WL glasses (45 and 50 wt%) were shown by XRD to contain spinel (trevorite, NiFe2O4). It is possible that some of the other high WL glasses also contained some nepheline, but that the amount of nepheline crystallization was below the detection limit (0.5 vol%) associated with XRD. The results indicate that Frit 503 is a good candidate for SB4 processing, based on chemical durability of homogeneous and devitrified glasses over a WL range of 30 - 50%. It should be noted that the higher WL glasses would not be fit for processing in DWPF as they exceed other process related criteria (such as liquidus temperature). However, this is only one of many factors influencing the frit selection. Melt rate and the final SB4 composition are also important factors in frit selection. Additional melt rate studies are currently underway, and the final composition projection for SB4 is expected shortly.

Chemical Composition Analysis and Product Consistency Tests Supporting Refinement of the Nepheline Model for the High Aluminum Hanford Glass Composition Region

Download Chemical Composition Analysis and Product Consistency Tests Supporting Refinement of the Nepheline Model for the High Aluminum Hanford Glass Composition Region PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 247 pages
Book Rating : 4.:/5 (946 download)

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Book Synopsis Chemical Composition Analysis and Product Consistency Tests Supporting Refinement of the Nepheline Model for the High Aluminum Hanford Glass Composition Region by :

Download or read book Chemical Composition Analysis and Product Consistency Tests Supporting Refinement of the Nepheline Model for the High Aluminum Hanford Glass Composition Region written by and published by . This book was released on 2016 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report, Savannah River National Laboratory provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated high level waste (HLW) glasses fabricated by Pacific Northwest National Laboratory (PNNL) as part of an ongoing nepheline crystallization study. The results of these analyses will be used to improve the ability to predict crystallization of nepheline as a function of composition and heat treatment for glasses formulated at high alumina concentrations.

Optical Basicity and Nepheline Crystallization in High Alumina Glasses

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (754 download)

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Book Synopsis Optical Basicity and Nepheline Crystallization in High Alumina Glasses by :

Download or read book Optical Basicity and Nepheline Crystallization in High Alumina Glasses written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO4) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimental basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV. To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage. Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.

EXPERIMENTAL RESULTS OF THE NEPHELINE PHASE III STUDY.

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis EXPERIMENTAL RESULTS OF THE NEPHELINE PHASE III STUDY. by :

Download or read book EXPERIMENTAL RESULTS OF THE NEPHELINE PHASE III STUDY. written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is the third phase in a series of experiments designed to reduce conservatism in the model that predicts the formation of nepheline, a crystalline phase that can reduce the durability of high level waste glass. A Phase I study developed a series of glass compositions that were very durable while their nepheline discriminator values were well below the current nepheline discriminator limit of 0.62, where nepheline is predicted to crystallize upon slow cooling. A Phase II study selected glass compositions to identify any linear effects of composition on nepheline crystallization and that were restricted to regions that fell within the validation ranges of the Defense Waste Processing Facility (DWPF) Product Composition Control System (PCCS) models. However, it was not possible to identify any linear effects of composition on chemical durability performance for this set of study glasses. The results of the Phase II study alone were not sufficient to recommend modification of the current nepheline discriminator. It was recommended that the next series of experiments continue to focus not only on compositional regions where the PCCS models are considered applicable (i.e., the model validation ranges), but also be restricted to compositional regions where the only constraint limiting processing is the current nepheline discriminator. Two methods were used in selecting glasses for this Phase III nepheline study. The first was based on the relationship of the current nepheline discriminator model to the other DWPF PCCS models, and the second was based on theory of crystallization in mineral and glass melts. A series of 29 test glass compositions was selected for this study using a combination of the two approaches. The glasses were fabricated and characterized in the laboratory. After reviewing the data, the study glasses generally met the target compositions with little issue. Product Consistency Test results correlated well with the crystallization analyses in that those glasses that were found to contain nepheline after the centerline canister cooled (ccc) heat treatment generally had normalized release values that were greater than their quenched counterparts on a statistically significant basis. The current nepheline discriminator as implemented at the DWPF was shown to continue to work well in predicting nepheline prone glass compositions. A main objective of this study was to identify any compositional regions where conservatism in the current nepheline discriminator was preventing access to those regions that would otherwise be acceptable for DWPF processing by the PCCS models. Four glasses (based on the measured compositions) were identified through this study that met those criteria. However, a review of the individual compositions of these glasses revealed no clear trends that might indicate a driver for suppression of nepheline. Another objective of this study was to evaluate an alternative nepheline discriminator model developed using theory of crystallization in mineral and glass melts. Unfortunately this new model, in its current state, was unsuccessful in predicting nepheline crystallization in the glass compositions selected for this study. It is recommended that the data collected in this study be incorporated into the new model for further refinement.

The Effect of Adding Crystalline Silicotitanate on the Durability, Liquidus, and Viscosity of Simulated High-level Waste Glasses at Savannah River Site

Download The Effect of Adding Crystalline Silicotitanate on the Durability, Liquidus, and Viscosity of Simulated High-level Waste Glasses at Savannah River Site PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (684 download)

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Book Synopsis The Effect of Adding Crystalline Silicotitanate on the Durability, Liquidus, and Viscosity of Simulated High-level Waste Glasses at Savannah River Site by :

Download or read book The Effect of Adding Crystalline Silicotitanate on the Durability, Liquidus, and Viscosity of Simulated High-level Waste Glasses at Savannah River Site written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Technical Note

Author : Gregory F. Piepel
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (821 download)

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Book Synopsis Technical Note by : Gregory F. Piepel

Download or read book Technical Note written by Gregory F. Piepel and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

CRYSTALLIZATION IN HIGH-LEVEL WASTE GLASSES U.S. DEPARTMENT OF ENERGY OFFICE OF RIVER PROTECTION WTP ENGINEERING DIVISION.

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis CRYSTALLIZATION IN HIGH-LEVEL WASTE GLASSES U.S. DEPARTMENT OF ENERGY OFFICE OF RIVER PROTECTION WTP ENGINEERING DIVISION. by :

Download or read book CRYSTALLIZATION IN HIGH-LEVEL WASTE GLASSES U.S. DEPARTMENT OF ENERGY OFFICE OF RIVER PROTECTION WTP ENGINEERING DIVISION. written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Various circumstances influence crystallization in glassmaking, for example: (1) crystals nucleate and grow before the glass-forming melt occurs; (2) crystals grow or dissolve in flowing melt and during changing temperature; (3) crystals move under the influence of gravity; (4) crystals agglomerate and interact with gas bubbles; (5) high-level wastes (HLW) are mixtures of a large number of components in unusual proportions; (6) melter processing of HLW and the slow cooling of HLW glass in canisters provides an opportunity for a variety of crystalline forms to precipitate; (7) settling of crystals in a HLW glass melter may produce undesirable sludge at the melter bottom; and (8) crystallization of the glass product may increase, but also ruin chemical durability. The conclusions are: (1) crystal growth and dissolution typically proceed in a convective medium at changing temperature; (2) to represent crystallization or dissolution the kinetics must be expressed in the form of rate equations, such as dC/dt = f(C, T) and the temperature dependence of kinetic coefficients and equilibrium concentrations must be accounted for; and (3) non-equilibrium phenomena commonly occur - metastable crystallization, periodic distribution of crystals; and dendritic crystal growth.

VITRIFICATION OF HIGH LEVEL WASTE AT THE SAVANNAH RIVER SITE.

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis VITRIFICATION OF HIGH LEVEL WASTE AT THE SAVANNAH RIVER SITE. by :

Download or read book VITRIFICATION OF HIGH LEVEL WASTE AT THE SAVANNAH RIVER SITE. written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study was to experimentally measure the properties and performance of a series of glasses with compositions that could represent high level waste Sludge Batch 5 (SB5) as vitrified at the Savannah River Site Defense Waste Processing Facility. These data were used to guide frit optimization efforts as the SB5 composition was finalized. Glass compositions for this study were developed by combining a series of SB5 composition projections with a group of candidate frits. The study glasses were fabricated using depleted uranium and their chemical compositions, crystalline contents and chemical durabilities were characterized. Trevorite was the only crystalline phase that was identified in a few of the study glasses after slow cooling, and is not of concern as spinels have been shown to have little impact on the durability of high level waste glasses. Chemical durability was quantified using the Product Consistency Test (PCT). All of the glasses had very acceptable durability performance. The results of this study indicate that a frit composition can be identified that will provide a processable and durable glass when combined with SB5.

MATRIX 2 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL.

Author :
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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis MATRIX 2 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL. by :

Download or read book MATRIX 2 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL. written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-level waste (HLW) throughput (i.e., the amount of waste processed per unit time) is a function of two critical parameters: waste loading (WL) and melt rate. For the Waste Treatment and Immobilization Plant (WTP) at the Hanford Site and the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS), increasing HLW throughput would significantly reduce the overall mission life cycle costs for the Department of Energy (DOE). The objective of this study was to generate supplemental validation data that could be used to determine the applicability of the current liquidus temperature (TL) model to expanded DWPF glass composition regions of interest based on higher WLs. Two specific flowsheets were used in this study to provide such insight: (1) Higher WL glasses (45 and 50%) based on future sludge batches that have (and have not) undergone the Al-dissolution process. (2) Coupled operations supported by the Salt Waste Processing Facility (SWPF), which increase the TiO2 concentration in glass to greater than 2 wt%. Glasses were also selected to address technical issues associated with Al2O3 solubility, nepheline formation, and homogeneity issues for coupled operations. A test matrix of 28 glass compositions was developed to provide insight into these issues. The glasses were fabricated and characterized using chemical composition analysis, X-ray Diffraction (XRD), TL measurement and the Product Consistency Test (PCT). The results of this study are summarized below: (1) TiO2 concentrations up to (almost equal to) 3.5 wt% were retained in DWPF type glasses, where retention is defined as the absence of crystalline TiO2 (i.e., unreacted or undissolved) in the as-fabricated glasses. Although this TiO2 content does not bound the projected SWPF high output flowsheet (up to 6 wt% TiO2 may be required in glass), these data demonstrate the potential for increasing the TiO2 limit in glass above the current limit of 2 wt% (based strictly on retention or solubility). (2) For those study glasses that had very close compositional overlap with the model development and/or model validation ranges of the current DWPF TL model (except TiO2 and MgO concentrations), there was very little difference in the predicted and measured TL values. Even though the TiO2 concentrations were above the 2 wt% upper limit, the results indicate that the current T{sub L} model is applicable in this compositional region with TiO2 contents up to approximately 3.5 wt%. (3) As the target glass compositions diverge from the model development and validation ranges, the T{sub L} data suggest that the model under-predicted the measured values. These discrepancies imply that there are individual oxides or oxide combinations that need to be accounted for in the model. These oxides include B2O3, SiO2, MnO, TiO2 and/or their combinations. More data would be required to fill in these anticipated DWPF compositional regions for higher WL glasses so that the model coefficients could be refit to account for these differences. (4) Based on PCT response of HWL-21 and HWL-22 (two glasses that were prone to nepheline formation) it appears that increasing the B2O3 concentration in glass does not consistently suppress the formation of nepheline in glasses with higher Al2O3 and/or Na2O content. Although the chemical durabilities of the quenched versions of these glasses were very acceptable, the canister centerline cooled (ccc) glasses exhibited a considerable decrease in durability and were found to contain nepheline via XRD. In fact, one of the glasses had a release that was 5 times greater than that of the Environmental Assessment (EA) benchmark glass. These results suggest a need for a more fundamental understanding of the compositional and kinetic effects of nepheline formation in high WL glasses. (5) Data have been generated in support of the replacement of the homogeneity constraint with the Al2O3 and/or sum of alkali constraints for coupled operations as previously completed for sludge-only operations. This strategy should be pursued for either the compositional region anticipated for coupled operations or as part of the variability study for each sludge batch. The PCT responses of the study glasses suggest a high probability that this strategy could be defended at some later date.

Production and Remediation of Low Sludge Simulated Purex Waste Glasses, 2

Author :
Publisher :
ISBN 13 :
Total Pages : 13 pages
Book Rating : 4.:/5 (685 download)

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Book Synopsis Production and Remediation of Low Sludge Simulated Purex Waste Glasses, 2 by :

Download or read book Production and Remediation of Low Sludge Simulated Purex Waste Glasses, 2 written by and published by . This book was released on 1993 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glass produced during the Purex 4 campaigns of the Integrated DWPF Melter System (IDMS) and the 774 Research Melter contained a lower fraction of sludge components than targeted by the Product Composition Control System (PCCS). Purex 4 glass was more durable than the benchmark (EA) glass, but was less durable than most other simulated SRS high-level waste glasses. Further, the measured durability of Purex 4 glass was not as well correlated with the durability predicted from the DWPF process control algorithm, probably because the algorithm was developed to predict the durability of SRS high-level waste glasses with higher sludge content than Purex 4. A melter run, designated Purex 4 Remediation, was performed using the 774 Research Melter to determine if the initial PCCS target composition determined for Purex 4 would produce acceptable glass whose durability could be accurately modeled by the DWPF glass durability algorithm. Reagent grade oxides and carbonates were added to Purex 4 melter feed stock to simulate a higher sludge loading. Each canister of glass produced was sampled and the glass durability was determined by the Product Consistency Test method. This document details the durability data and subsequent analysis.

The Effect of Vitrification Technology on Waste Loading

Author :
Publisher :
ISBN 13 :
Total Pages : 10 pages
Book Rating : 4.:/5 (683 download)

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Book Synopsis The Effect of Vitrification Technology on Waste Loading by :

Download or read book The Effect of Vitrification Technology on Waste Loading written by and published by . This book was released on 1994 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive wastes on the Hanford Site are going to be permanently disposed of by incorporation into a durable glass. These wastes will be separated into low and high-level portions, and then vitrified. The low-level waste (LLW) is water soluble. Its vitrifiable part (other than off-gas) contains approximately 80 wt% Na2O, the rest being Al2O3, P2O5, K2O, and minor components. The challenge is to formulate durable LLW glasses with as high Na2O content as possible by optimizing the additions of SiO2, Al2O3, B2O3, CaO, and ZrO2. This task will not be simple, considering the non-linear and interactive nature of glass properties as a function of composition. Once developed, the LLW glass, being similar in composition to commercial glasses, is unlikely to cause major processing problems, such as crystallization or molten salt segregation. For example, inexpensive LLW glass can be produced in a high-capacity Joule-heated melter with a cold cap to minimize volatilization. The high-level waste (HLW) consists of water-insoluble sludge (Fe2O3, Al2O3, ZrO2, Cr2O3, NiO, and others) and a substantial water-soluble residue (Na2O). Most of the water-insoluble components are refractory; i.e., their melting points are above the glass melting temperature. With regard to product acceptability, the maximum loading of Hanford HLW in the glass is limited by product durability, not by radiolytic heat generation. However, this maximum may not be achievable because of technological constraints imposed by melter feed rheology, frit properties, and glass melter limits. These restrictions are discussed in this paper. 38 refs.

Structure of Glasses and Glass-Forming Liquids with Application to Nuclear Waste Vitrification

Author : Emily Taapke Nienhuis
Publisher :
ISBN 13 :
Total Pages : 324 pages
Book Rating : 4.6/5 (781 download)

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Book Synopsis Structure of Glasses and Glass-Forming Liquids with Application to Nuclear Waste Vitrification by : Emily Taapke Nienhuis

Download or read book Structure of Glasses and Glass-Forming Liquids with Application to Nuclear Waste Vitrification written by Emily Taapke Nienhuis and published by . This book was released on 2020 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phase separation during the vitrification of nuclear waste can be detrimental to the processing of nuclear waste as well as the long-term chemical durability of the glassy waste form. In Hanford Low Activity Waste, phase separation due to the formation of a molten salt phase during batch-to-glass conversion can decrease the lifetime of the Joule-heated ceramic melters as well as form a water-soluble crystalline salt phase on cooling. In Hanford High-Level Waste, the high-Na and high-Al contents can promote crystallization of nepheline, and related phases, on cooling from melt, which decreases the long-term chemical durability of the glass. This study seeks to understand these examples of phase separation in simplified compositions through structural analysis of the melt, glass, and resulting crystalline phases. In the simplified Low Activity Waste composition studies, the structures of mixed halide-sulfate systems are analyzed and related to the structure of traditional glass-forming materials. In the simplified High-Level Waste composition studies, melts and glasses related to the nominal nepheline composition (NaAlSiO4) are of interest for structure-crystallization relationships. The structure of these materials has been probed through X-ray and neutron total scattering and was supplemented with atomistic simulation, Raman spectroscopy, X-ray absorption spectroscopy, and other methods. Implications for phase separation in these materials are drawn based upon the local environments of oxyanions in the salt-based materials and dopant species in the nepheline-based compositions.

Hanford Enhanced Waste Glass Characterization. Influence of Composition on Chemical Durability

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ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis Hanford Enhanced Waste Glass Characterization. Influence of Composition on Chemical Durability by :

Download or read book Hanford Enhanced Waste Glass Characterization. Influence of Composition on Chemical Durability written by and published by . This book was released on 2016 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Control of Nepheline Crystallization in Nuclear Waste Glass

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis Control of Nepheline Crystallization in Nuclear Waste Glass by :

Download or read book Control of Nepheline Crystallization in Nuclear Waste Glass written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Glass frits with a high B2O3 concentration have been designed which, when combined with high-alumina concentration nuclear waste streams, will form glasses with durabilities that are acceptable for repository disposal and predictable using a free energy of hydration model. Two glasses with nepheline discriminator values closest to 0.62 showed significant differences in normalized boron release between the quenched and heat treated versions of each glass. X-ray diffraction confirmed that nepheline crystallized in the glass with the lowest nepheline discriminator value, and nepheline may also exist in the second glass as small nanocrystals. The high-B2O3 frit was successful in producing simulated waste glasses with no detectable nepheline crystallization at waste loadings of up to 45 wt%. The melt rate of this frit was also considerably better than other frits with increased concentrations of Na2O.