Engineering topics
Edwards, T
Publications and source records attributed to Edwards, T.
IMPACT OF URANIUM AND THORIUM ON HIGH TIO2 CONCENTRATION NUCLEAR WASTE GLASSES
This study focused on the potential impacts of the addition of Crystalline Silicotitanate (CST) and Monosodium Titanate (MST) from the Small Column Ion Exchange (SCIX) process on the Defense Waste Processing Facility (DWPF) glass waste form and the applicability of the DWPF process control models. MST from the Salt Waste Processing Facility (SWPF) is also considered in the study. The KT08-series of glasses was designed to evaluate any impacts of the inclusion of uranium and thorium in glasses containing the SCIX components. All but one of the study glasses were found to be amorphous by X-ray diffraction (XRD). One of the slowly cooled glasses contained a small amount of trevorite, which is typically found in DWPF-type glasses and had no practical impact on the durability of the glass. The measured Product Consistency Test (PCT) responses for the study glasses and the viscosities of the glasses were well predicted by the current DWPF models. No unexpected issues were encountered when uranium and thorium were added to the glasses with SCIX components.
ISOLOK VALVE ACCEPTANCE TESTING FOR DWPF SME SAMPLING PROCESS
Evaluation of the Defense Waste Processing Facility (DWPF) Chemical Process Cell (CPC) cycle time identified several opportunities to improve the CPC processing time. Of the opportunities, a focus area related to optimizing the equipment and efficiency of the sample turnaround time for DWPF Analytical Laboratory was identified. The Mechanical Systems & Custom Equipment Development (MS&CED) Section of the Savannah River National Laboratory (SRNL) evaluated the possibility of using an Isolok{reg_sign} sampling valve as an alternative to the Hydragard{reg_sign} valve for taking process samples. Previous viability testing was conducted with favorable results using the Isolok sampler and reported in SRNL-STI-2010-00749 (1). This task has the potential to improve operability, reduce maintenance time and decrease CPC cycle time. This report summarizes the results from acceptance testing which was requested in Task Technical Request (TTR) HLW-DWPF-TTR-2010-0036 (2) and which was conducted as outlined in Task Technical and Quality Assurance Plan (TTQAP) SRNL-RP-2011-00145 (3). The Isolok to be tested is the same model which was tested, qualified, and installed in the Sludge Receipt Adjustment Tank (SRAT) sample system. RW-0333P QA requirements apply to this task. This task was to qualify the Isolok sampler for use in the DWPF Slurry Mix Evaporator (SME) sampling process. The Hydragard, which is the current baseline sampling method, was used for comparison to the Isolok sampling data. The Isolok sampler is an air powered grab sampler used to 'pull' a sample volume from a process line. The operation of the sampler is shown in Figure 1. The image on the left shows the Isolok's spool extended into the process line and the image on the right shows the sampler retracted and then dispensing the liquid into the sampling container. To determine tank homogeneity, a Coliwasa sampler was used to grab samples at a high and low location within the mixing tank. Data from the two locations were compared to determine if the contents of the tank were well mixed. The Coliwasa sampler is a tube with a stopper at the bottom and is designed to obtain grab samples from specific locations within the drum contents. A position paper (4) was issued to address the prototypic flow loop issues and simulant selections. A statistically designed plan (5) was issued to address the total number of samples each sampler needed to pull, to provide the random order in which samples were pulled and to group samples for elemental analysis. The TTR required that the Isolok sampler perform as well as the Hydragard sampler during these tests to ensure the acceptability of the Isolok sampler for use in the DWPF sampling cells. Procedure No.L9.4-5015 was used to document the sample parameters and process steps. Completed procedures are located in R&D Engineering job folder 23269.
EVALUATION OF ARG-1 SAMPLES PREPARED BY CESIUM CARBONATE DISSOLUTION DURING THE ISOLOK SME ACCEPTABILITY TESTING
Evaluation of Defense Waste Processing Facility (DWPF) Chemical Process Cell (CPC) cycle time identified several opportunities to improve the CPC processing time. The Mechanical Systems & Custom Equipment Development (MS&CED) Section of the Savannah River National Laboratory (SRNL) recently completed the evaluation of one of these opportunities - the possibility of using an Isolok sampling valve as an alternative to the Hydragard valve for taking DWPF process samples at the Slurry Mix Evaporator (SME). The use of an Isolok for SME sampling has the potential to improve operability, reduce maintenance time, and decrease CPC cycle time. The SME acceptability testing for the Isolok was requested in Task Technical Request (TTR) HLW-DWPF-TTR-2010-0036 and was conducted as outlined in Task Technical and Quality Assurance Plan (TTQAP) SRNLRP-2011-00145. RW-0333P QA requirements applied to the task, and the results from the investigation were documented in SRNL-STI-2011-00693. Measurement of the chemical composition of study samples was a critical component of the SME acceptability testing of the Isolok. A sampling and analytical plan supported the investigation with the analytical plan directing that the study samples be prepared by a cesium carbonate (Cs{sub 2}CO{sub 3}) fusion dissolution method and analyzed by Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES). The use of the cesium carbonate preparation method for the Isolok testing provided an opportunity for an additional assessment of this dissolution method, which is being investigated as a potential replacement for the two methods (i.e., sodium peroxide fusion and mixed acid dissolution) that have been used at the DWPF for the analysis of SME samples. Earlier testing of the Cs{sub 2}CO{sub 3} method yielded promising results which led to a TTR from Savannah River Remediation, LLC (SRR) to SRNL for additional support and an associated TTQAP to direct the SRNL efforts. A technical report resulting from this work was issued that recommended that the mixed acid method be replaced by the Cs{sub 2}CO{sub 3} method for the measurement of magnesium (Mg), sodium (Na), and zirconium (Zr) with additional testing of the method by DWPF Laboratory being needed before further implementation of the Cs{sub 2}CO{sub 3} method at that laboratory. While the SME acceptability testing of the Isolok does not address any of the open issues remaining after the publication of the recommendation for the replacement of the mixed acid method by the Cs{sub 2}CO{sub 3} method (since those issues are to be addressed by the DWPF Laboratory), the Cs{sub 2}CO{sub 3} testing associated with the Isolok testing does provide additional insight into the performance of the method as conducted by SRNL. The performance is to be investigated by looking to the composition measurement data generated by the samples of a standard glass, the Analytical Reference Glass - 1 (ARG-1), that were prepared by the Cs{sub 2}CO{sub 3} method and included in the SME acceptability testing of the Isolok. The measurements of these samples were presented as part of the study results, but no statistical analysis of these measurements was conducted as part of those results. It is the purpose of this report to provide that analysis, which was supported using JMP Version 7.0.2.
PREDICTION OF DISSOLVER LIFETIMES THROUGH NON-DESTRUCTIVE EVALUATION AND LABORATORY TESTING
Non-destructive evaluation was used as the primary method of monitoring the corrosion degradation of nuclear material dissolvers and assessing the remaining lifetimes. Materials were typically processed in nitric acid based (4-14M) solutions containing fluoride concentrations less than 0.2 M. The primary corrosion issue for the stainless steel dissolvers is the occurrence of localized corrosion near the tank bottom and the heat affected zones of the welds. Laboratory data for a range of operational conditions, including solution chemistry and temperature, was used to assess the impact of processing changes on the dissolver corrosion rate. Experimental and NDE-based general corrosion rates were found to be in reasonable agreement for standard dissolution chemistries consisting of nitric acid with fluorides and at temperatures less than 95 C. Greater differences were observed when chloride was present as an impurity and temperatures exceeded 100 C.
VERIFICATION OF THE DEFENSE WASTE PROCESSING FACILITY'S (DWPF) PROCESS DIGESTION METHOD FOR THE SLUDGE BATCH 7B BLEND SAMPLE
No abstract prepared.
MAR ASSESSMENTS OF THE HIGH LEVEL WASTE SYSTEM PLAN REVISION 16
High-level waste (HLW) throughput (i.e., the amount of waste processed per unit of time) is primarily a function of two critical parameters: waste loading (WL) and melt rate. For the Defense Waste Processing Facility (DWPF), increasing HLW throughput would significantly reduce the overall mission life cycle costs for the Department of Energy (DOE). Significant increases in waste throughput have been achieved at DWPF since initial radioactive operations began in 1996. Key technical and operational initiatives that supported increased waste throughput included improvements in facility attainment, the Chemical Processing Cell (CPC) flowsheet, process control models and frit formulations. As a result of these key initiatives, DWPF increased WLs from a nominal 28% for Sludge Batch 2 (SB2) to {approx}34 to 38% for SB3 through SB6 while maintaining or slightly improving canister fill times. Although considerable improvements in waste throughput have been obtained, future contractual waste loading targets are nominally 40%, while canister production rates are also expected to increase (to a rate of 325 to 400 canisters per year). Although implementation of bubblers have made a positive impact on increasing melt rate for recent sludge batches targeting WLs in the mid30s, higher WLs will ultimately make the feeds to DWPF more challenging to process. Savannah River Remediation (SRR) recently requested the Savannah River National Laboratory (SRNL) to perform a paper study assessment using future sludge projections to evaluate whether the current Process Composition Control System (PCCS) algorithms would provide projected operating windows to allow future contractual WL targets to be met. More specifically, the objective of this study was to evaluate future sludge batch projections (based on Revision 16 of the HLW Systems Plan) with respect to projected operating windows using current PCCS models and associated constraints. Based on the assessments, the waste loading interval over which a glass system (i.e., a projected sludge composition with a candidate frit) is predicted to be acceptable can be defined (i.e., the projected operating window) which will provide insight into the ability to meet future contractual WL obligations. In this study, future contractual WL obligations are assumed to be 40%, which is the goal after all flowsheet enhancements have been implemented to support DWPF operations. For a system to be considered acceptable, candidate frits must be identified that provide access to at least 40% WL while accounting for potential variation in the sludge resulting from differences in batch-to-batch transfers into the Sludge Receipt and Adjustment Tank (SRAT) and/or analytical uncertainties. In more general terms, this study will assess whether or not the current glass formulation strategy (based on the use of the Nominal and Variation Stage assessments) and current PCCS models will allow access to compositional regions required to targeted higher WLs for future operations. Some of the key questions to be considered in this study include: (1) If higher WLs are attainable with current process control models, are the models valid in these compositional regions? If the higher WL glass regions are outside current model development or validation ranges, is there existing data that could be used to demonstrate model applicability (or lack thereof)? If not, experimental data may be required to revise current models or serve as validation data with the existing models. (2) Are there compositional trends in frit space that are required by the PCCS models to obtain access to these higher WLs? If so, are there potential issues with the compositions of the associated frits (e.g., limitations on the B{sub 2}O{sub 3} and/or Li{sub 2}O concentrations) as they are compared to model development/validation ranges or to the term 'borosilicate' glass? If limitations on the frit compositional range are realized, what is the impact of these restrictions on other glass properties such as the ability to suppress nepheline formation or influence melt rate? The model based assessments being performed make the assumption that the process control models are applicable over the glass compositional regions being evaluated. Although the glass compositional region of interest is ultimately defined by the specific frit, sludge, and WL interval used, there is no prescreening of these compositional regions with respect to the model development or validation ranges which is consistent with current DWPF operations.
Qualification of a Carbon Analyzer to Support the Defense Waste Processing Facility
The I-O Model 1030 carbon analyzer has been qualified for use at the Defense Waste Processing Facility (DWPF). The qualification was a side-by-side comparison of the Model 1030 system with the currently used Model 1010 Analyzer. This recommendation is based on side-by-side comparisons of the new unit to the currently used Model 1010 analyzer that are presented in this report. The side-by-side testing included standards and process samples. The standards, which were used for instrument calibration verifications in the measurement of total inorganic carbon (TIC) and of total organic carbon (TOC), were traceable back to the National Institute of Standards and Technology. The process samples included TIC analyses of Sludge Receipt and Adjustment Tank samples and TOC analyses for Slurry Mix Evaporator (SME) samples. After the Model 1030 has been used for production reporting, DWPF should consider an investigation into the uncertainties associated with the TOC measurements to determine how far below the 18,916 ppm limit DWPF must control the average of the measurements for a set of SME samples to account for the uncertainties of the measurements from this new analyzer. Based upon the results presented in this report, it is recommended that the Model 1030 carbon analyzer is qualified for use. This recommendation is based on side-by-side comparisons of the new unit to the currently used Model 1010 analyzer that are presented in this report. The side-by-side testing included standards for instrument calibration verifications for TIC and TOC, and process samples. The standards were traceable back to NIST. The process samples included TIC analyses of SRAT Receipt samples and TOC analyses for SME samples. At some point in the future, after the Model 1030 has been used for production reporting, DWPF should consider an investigation into the uncertainties associated with the TOC measurements to determine how far below the 18,916 ppm limit DWPF must control the average of the measurements for a set of SME samples to account for the uncertainties of the measurements from this new analyzer.
Qualification of the First ICS-3000 ION Chromatograph for use at the Defense Waste Processing Facility
The ICS-3000 Ion Chromatography (IC) system installed in 221-S M-13 has been qualified for use. The qualification was a head to head comparison of the ICS-3000 with the currently used DX-500 IC system. The crosscheck work included standards for instrument calibration and calibration verifications and standards for individual anion analysis, where the standards were traceable back to the National Institute of Standards and Technology (NIST). In addition the crosscheck work included the analysis of simulated Sludge Receipt Adjustment Tank (SRAT) Receipt, SRAT Product, and Slurry Mix Evaporator (SME) samples, along with radioactive Sludge Batch 5 material from the SRAT and SME tanks. Based upon the successful qualification of the ICS-3000 in M-13, it is recommended that this task proceed in developing the data to qualify, by a head to head comparison of the two ICS-3000 instruments, a second ICS-3000 to be installed in M-14. The Defense Waste Processing Facility (DWPF) requires the analysis of specific anions at various stages of its processing of high level waste (HLW). The anions of interest to the DWPF are fluoride, formate, chloride, nitrite, nitrate, sulfate, oxalate, and phosphate. The anion analysis is used to evaluate process chemistry including formic acid/nitric acid additions to establish optimum conditions for mercury stripping, reduction-oxidation (REDOX) chemistry for the melter, nitrite destruction, organic acid constituents, etc. The DWPF Laboratory (Lab) has been using Dionex DX-500 ion chromatography (IC) systems since 1998. The vendor informed DWPF in 2006 that the instruments would no longer be supported by service contracts after 2008. DWPF purchased three new ICS-3000 systems in September of 2006. The ICS-3000 instruments are (a) designed to be more stable using an eluent generator to make eluent, (b) require virtually no daily chemical handling by the analysts, (c) require less line breaks in the hood, and (d) generally require less maintenance due to the pump configuration only using water versus the current system where the pump uses various hydroxide concentrations. The ICS-3000 instruments also allow the DWPF to maintain current service contracts, which support routine preventive maintenance and emergency support for larger problems such as component failure. One of the three new systems was set up in the DWPF Lab trailers in January of 2007 to be used for the development of methods and procedures. This system will continue to be used for training, new method development and potential improvements to current methods. The qualification of the other two ICS-3000 instruments is to be a phased effort. This effort is to be supported by the Applied Computational Engineering and Statistical (ACES) group of the Savannah River National Laboratory (SRNL) as authorized by the Technical Task Request (TTR) and as directed by the corresponding Task Technical and Quality Assurance (TT&QA) plan. The installation of the first 'rad' system into the M-13 Lab module required modifications to both the Lab module and to the radiohood. The installation was completed in July 2008. The testing of this system was conducted as directed by the TT&QA plan. The purpose of this technical report is to provide a review of the data generated by these tests that will lead to the recommendation for the qualification of the M-13 ICS-3000 instrument. With the successful qualification of this first ICS-3000, plans will be developed for the installation of the second 'rad' system in the M-14 Lab module later in fiscal year 2009. When the second 'rad' ICS-3000 system is installed, the DX-500 systems will be removed and retired from service.
Qualification of the Nippon Instrumentation for use in Measuring Mercury at the Defense Waste Processing Facility
The Nippon Mercury/RA-3000 system installed in 221-S M-14 has been qualified for use. The qualification was a side-by-side comparison of the Nippon Mercury/RA-3000 system with the currently used Bacharach Mercury Analyzer. The side-by-side testing included standards for instrument calibration verifications, spiked samples and unspiked samples. The standards were traceable back to the National Institute of Standards and Technology (NIST). The side-by-side work included the analysis of Sludge Receipt and Adjustment Tank (SRAT) Receipt, SRAT Product, and Slurry Mix Evaporator (SME) samples. With the qualification of the Nippon Mercury/RA-3000 system in M-14, the DWPF lab will be able to perform a head to head comparison of a second Nippon Mercury/RA-3000 system once the system is installed. The Defense Waste Processing Facility (DWPF) analyzes receipt and product samples from the Sludge Receipt and Adjustment Tank (SRAT) to determine the mercury (Hg) concentration in the sludge slurry. The SRAT receipt is typically sampled and analyzed for the first ten SRAT batches of a new sludge batch to obtain an average Hg concentration. This average Hg concentration is then used to determine the amount of steam stripping required during the concentration/reflux step of the SRAT cycle to achieve a less than 0.6 wt% Hg in the SRAT product solids. After processing is complete, the SRAT product is sampled and analyzed for mercury to ensure that the mercury concentration does not exceed the 0.45 wt% limit in the Slurry Mix Evaporator (SME). The DWPF Laboratory utilizes Bacharach Analyzers to support these Hg analyses at this facility. These analyzers are more than 10 years old, and they are no longer supported by the manufacturer. Due to these difficulties, the Bacharach Analyzers are to be replaced by new Nippon Mercury/RA-3000 systems. DWPF issued a Technical Task Request (TTR) for the Savannah River National Laboratory (SRNL) to assist in the qualification of the new systems. SRNL prepared a task technical and quality assurance (TT&QA) plan that outlined the activities that are necessary and sufficient to meet the objectives of the TTR. In addition, TT&QA plan also included a test plan that provided guidance to the DWPF Lab in collecting the data needed to qualify the new Nippon Mercury/RA-3000 systems.
DWPF FLOWSHEET STUDIES WITH SIMULANT TO DETERMINE THE IMPACT OF NEXT GENERATION SOLVENT ON THE CPC PROCESS AND GLASS FORMULATION
As a part of the Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) Life Extension Project, a next generation solvent (NGS), a new strip acid, and modified monosodium titanate (mMST) will be deployed. The NGS is comprised of four components: 0.050 M MaxCalix (extractant), 0.50 M Cs-7SB (modifier), 0.003 M guanidine-LIX-79, with the balance ({approx}74 wt%) being Isopar{reg_sign} L. The strip acid will be changed from dilute nitric acid to dilute boric acid (0.01 M). Because of these changes, experimental testing with the next generation solvent and mMST was required to determine the impact of these changes in 512-S and Defense Waste Processing Facility (DWPF) operations, as well as Chemical Process Cell (CPC), glass formulation activities, and melter operations. Because of these changes, experimental testing with the next generation solvent and mMST is required to determine the impact of these changes. A Technical Task Request (TTR) was issued to support the assessments of the impact of the next generation solvent and mMST on the downstream DWPF flowsheet unit. The TTR identified five tasks to be investigated: (1) CPC Flowsheet Demonstration for NGS; (2) Solvent Stability for DWPF CPC Conditions; (3) Glass Formulation Studies; (4) Boron Volatility and Melt Rate; and (5) CPC Flowsheet Demonstration for mMST.
RHEOLOGY OF SETTLED SOLIDS IN THE SMALL COLUMN ION EXCHANGE PROCESS
The Small Column Ion Exchange (SCIX) process is being developed to remove cesium, strontium, and actinides from Savannah River Site (SRS) Liquid Waste using an existing waste tank as process housing. This method includes the addition of monosodium titanate (MST) to a waste tank containing salt solution and entrained sludge solids, followed by tank mixing and filtration. The filtrate is then processed through in-tank ion exchange columns containing crystalline silicotitanate (CST) media. While the process is operating, it is known that solid particles begin to settle in the tank and temperatures may reach beyond 45 C. Previous testing has shown that sludge-MST slurries that sit for extended periods at elevated temperatures can develop large shear strengths, making them difficult to resuspend and remove from the tank. The authors conducted rheological testing of mixtures containing various concentrations of sludge simulant, MST, and CST (three preparations) that were aged at different times (i.e., 0 to 13 weeks) and isothermally maintained to 30, 45, or 60 C. Two types of grinding methodologies were employed to prepare CST for this testing, herein called Savannah River National Laboratory (SRNL) and Vitreous State Laboratory (VSL) ground materials. Unground CST particles were also tested. A small number of samples were irradiated prior to 4 week settling and 60 C temperature treatment, with exposures ranging from 0 to 100 MRad. Additional tests are also being conducted that will allow the solid particles to settle at 45 C for 6, 12, and 24 months. The objectives of this task are to determine the impact of feed composition, settling time, and temperature on the shear strength, yield stress, and consistency of the slurries and to determine the impact of radiation on slurry rheology. The testing will determine the relative impact of these parameters rather than predict the shear strength, yield stress, and consistency as a function of feed and operating conditions. This document describes the rheology of slurries containing MST, CST, and simulated sludge that sat at indicated temperatures for up to 13 weeks. A previous SRNL report described preliminary rheology data of slurries containing MST and sludge. Preliminary results of the irradiation tests are also presented in this report, though additional data are still being collected. Rheology of the long term settling samples (6, 12, and 24 months) and additional irradiation test results will be reported at a later date. Conclusions from this analysis are as follows: (1) Slurries containing MST and unground CST have the largest shear strength. Due to the high shear strengths measured in slurries containing unground CST, evaluations of specific tank contents and mixing capability should be performed prior to any addition of this material into a waste tank. Experimentally determined shear strengths indicate mixing could be problematic in mixtures containing unground CST. (2) Increasing the ground CST fraction in the slurry increases the slurry shear strength, yield stress, and consistency. (3) Increasing the sludge fraction in the slurry decreases the slurry shear strength, yield stress, and consistency. (4) Slurries containing VSL ground CST have larger shear strength, yield stress, and consistency than slurries containing SRNL ground CST. (5) The effects of settling time and temperature on slurry shear strength are slurry dependent. (6) No effects of settling time and temperature on slurry yield stress or consistency were observed. (7) Radiation up to 100 MRad does not appear to affect properties of shear strength, yield stress, or consistency of process feeds.
SUMMARY REPORT ON POTENTIAL IMPACTS OF SMALL COLUMN ION EXCHANGE ON DWPF GLASS FORMULATION
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.
IMPACTS OF SMALL COLUMN ION EXCHANGE STREAMS ON DWPF GLASS FORMULATION: KT08, KT09, AND KT10-SERIES GLASS COMPOSITIONS
This report is the fourth in a series of studies of the impacts of the addition of Crystalline Silicotitanate (CST) and Monosodium Titanate (MST) from the Small Column Ion Exchange (SCIX) process on the Defense Waste Processing Facility (DWPF) glass waste form and the applicability of the DWPF process control models. MST from the Salt Waste Processing Facility (SWPF) is also considered in the study. The KT08-series of glasses was designed to evaluate any impacts of the inclusion of uranium and thorium in glasses containing the SCIX components. The KT09-series of glasses was designed to study the effect of increasing Al{sub 2}O{sub 3} and K{sub 2}O concentrations on the propensity for crystallization of titanium containing phases in high TiO{sub 2} concentration glasses. Earlier work on the KT05-series glasses recommended that the impact of these two components be studied further. Increased Al{sub 2}O{sub 3} concentrations have been shown to improve the properties and performance of high waste loading glasses, and K{sub 2}O has been reported to improve the retention of TiO{sub 2} in silicate glasses. The KT10-series of compositions was designed to evaluate any impacts of the SCIX components at concentrations 50% higher than currently projected.a The glasses were fabricated in the laboratory and characterized to identify crystallization, to verify chemical compositions, to measure viscosity, and to measure durability. Liquidus temperature measurements for the KT10-series glasses are underway and will be reported separately. All but one of the KT08-series glasses were found to be amorphous by X-ray diffraction (XRD). One of the slowly cooled glasses contained a small amount of trevorite, which had no practical impact on the durability of the glass and is typically found in DWPF-type glasses. The measured Product Consistency Test (PCT) responses for the KT08-series glasses are well predicted by the DWPF models. The viscosities of the KT08-series glasses were generally well predicted by the DWPF model. No unexpected issues were encountered when uranium and thorium were added to the glasses with SCIX components. Increased Al{sub 2}O{sub 3} concentrations were not successful in preventing the formation of iron titanate crystals in the KT09-series glasses. Increased K{sub 2}O concentrations were successful in hindering the formation of iron titanates in some of the glasses after the canister centerline cooled (CCC) heat treatment. However, this result did not apply to all of the CCC versions of the glasses, indicating a compositional dependence of this effect. In addition, high concentrations of K{sub 2}O have been shown to hinder the ability of the DWPF durability and viscosity models to predict the performance of these glasses. The usefulness of increased K{sub 2}O concentrations in preventing the formation of iron titanates may therefore be limited. Further characterization was not performed for the KT09-series glasses since the type of crystallization formed was the characteristic of interest for these compositions. All of the KT10-series glasses were XRD amorphous, regardless of heat treatment. Chemical composition measurements showed that the glasses met the targeted concentrations for each oxide. In general, the measured PCT responses of the KT10-series glasses were well predicted by the DWPF models. The measured, normalized release values for silicon for some of the glasses fell above the 95% confidence interval for the predicted values; however, the PCT responses for these glasses remain considerably lower than that of the benchmark Environmental Assessment (EA) glass. The viscosities of the KT10-series glasses were generally well predicted by the DWPF model. The next step in this study will be to compile all of the data developed and further compare the measured properties and performance with those predicted by the current DWPF Product Composition Control System (PCCS) models. Recommendations will then be made as to which models, if any, may need to be modified in order to accommodate the material from SCIX into DWPF glass production.
UNCERTAINTIES OF ANION AND TOC MEASUREMENTS AT THE DWPF LABORATORY
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UNCERTAINTIES OF ANION AND TOC MEASUREMENTS AT THE DWPF LABORATORY
The Savannah River Remediation (SRR) Defense Waste Processing Facility (DWPF) has identified a technical issue related to the amount of antifoam added to the Chemical Process Cell (CPC). Specifically, due to the long duration of the concentration and reflux cycles for the Sludge Receipt and Adjustment Tank (SRAT), additional antifoam has been required. The additional antifoam has been found to impact the melter flammability analysis as an additional source of carbon and hydrogen. To better understand and control the carbon and hydrogen contributors to the melter flammability analysis, SRR's Waste Solidification Engineering (WSE) has requested, via a Technical Task Request (TTR), that the Savannah River National Laboratory (SRNL) conduct an error evaluation of the measurements of key Slurry Mix Evaporator (SME) anions. SRNL issued a Task Technical and Quality Assurance Plan (TTQAP) [2] in response to that request, and the work reported here was conducted under the auspices of that TTQAP. The TTR instructs SRNL to conduct an error evaluation of anion measurements generated by the DWPF Laboratory using Ion Chromatography (IC) performed on SME samples. The anions of interest include nitrate, oxalate, and formate. Recent measurements of SME samples for these anions as well as measurements of total organic carbon (TOC) were provided to SRNL by DWPF Laboratory Operations (Lab OPS) personnel for this evaluation. This work was closely coordinated with the efforts of others within SRNL that are investigating the Chemical Process Cell (CPC) contributions to the melter flammability. The objective of that investigation was to develop a more comprehensive melter flammability control strategy that when implemented in DWPF will rely on process measurements. Accounting for the uncertainty of the measurements is necessary for successful implementation. The error evaluations conducted as part of this task will facilitate the integration of appropriate uncertainties for the measurements utilized in that control strategy. The flammability control strategy presented in relies on SME measurements of TOC and nitrate while one of the uses by WSE of the oxalate and formate measurement data will be the estimation of the amount of carbon coming from antifoam additions. The estimation is to be conducted by backing out contributions to the measured TOC concentration in the SME from the oxalate and the formate concentrations that are measured in the SME. The resulting adjusted TOC value will provide a basis for WSE to estimate the amount of antifoam that was added for that SME batch. The uncertainties of the oxalate, formate, and TOC measurements provided by the evaluations conducted as part of this task will allow for the propagation of their uncertainties into the estimated quantity of carbon coming from the added antifoam. The purpose of this technical report is to present the measurements generated by the DWPF Laboratory for recent SME batches, to conduct an evaluation of their uncertainties, and to provide the approach for propagating the uncertainties associated with these measurements into DWPF's strategies for controlling melter flammability and for monitoring antifoam additions. JMP Version 7.0.2 was used to support the analyses presented in this report.
THE IMPACT OF THE MCU LIFE EXTENSION SOLVENT ON DWPF GLASS FORMULATION EFFORTS
As a part of the Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) Life Extension Project, a next generation solvent (NG-CSSX), a new strip acid, and modified monosodium titanate (mMST) will be deployed. The strip acid will be changed from dilute nitric acid to dilute boric acid (0.01 M). Because of these changes, experimental testing with the next generation solvent and mMST is required to determine the impact of these changes in 512-S operations as well as Chemical Process Cell (CPC), Defense Waste Processing Facility (DWPF) glass formulation activities, and melter operations at DWPF. To support programmatic objectives, the downstream impacts of the boric acid strip effluent (SE) to the glass formulation activities and melter operations are considered in this study. More specifically, the impacts of boric acid additions to the projected SB7b operating windows, potential impacts to frit production temperatures, and the potential impact of boron volatility are evaluated. Although various boric acid molarities have been reported and discussed, the baseline flowsheet used to support this assessment was 0.01M boric acid. The results of the paper study assessment indicate that Frit 418 and Frit 418-7D are robust to the implementation of the 0.01M boric acid SE into the SB7b flowsheet (sludge-only or ARP-added). More specifically, the projected operating windows for the nominal SB7b projections remain essentially constant (i.e., 25-43 or 25-44% waste loading (WL)) regardless of the flowsheet options (sludge-only, ARP added, and/or the presence of the new SE). These results indicate that even if SE is not transferred to the Sludge Receipt and Adjustment Tank (SRAT), there would be no need to add boric acid (from a trim tank) to compositionally compensate for the absence of the boric acid SE in either a sludge-only or ARP-added SB7b flowsheet. With respect to boron volatility, the Measurement Acceptability Region (MAR) assessments also suggest that Slurry Mix Evaporator (SME) acceptability decisions would not be different assuming either 100% of the B{sub 2}O{sub 3} from the SE were retained or volatilized. More specifically, the 0.84 wt% B{sub 2}O{sub 3} in the SE is so minor that its presence in the SME analysis does not influence SME acceptability decisions. In fact, using the 100% retention and 100% volatilization composition projections, only minor differences in the predicted properties of the glass product occur with all of the glasses being acceptable over a WL interval of 32-42%. Based on the 0.01M boric acid flowsheet, there is very little difference between Frit 418 and Frit 418-7D (a frit that was compositionally altered to account for the 0.84 wt% B{sub 2}O{sub 3} in the SE) with respect to melt temperature. In fact, when one evaluates the composition of Frit 418-7D, it lies within the current Frit 418 vendor specifications and therefore could have been produced by the vendor targeting the nominal composition of Frit 418.
THE SLUDGE BATCH 7A GLASS VARIABILITY STUDY WITH FRIT 418 AND FRIT 702
The Defense Waste Processing Facility (DWPF) is preparing to initiate processing of Sludge Batch 7a (SB7a) in May 2011. To support qualification of SB7a, the Savannah River National Laboratory (SRNL) was requested to execute a variability study (VS) to assess the applicability of the current Product Composition Control System (PCCS) durability models for the Frit 418-SB7a compositional region of interest. The objective of this study was to demonstrate applicability of the current durability models to the SB7a compositional region of interest and acceptability of the SB7a glasses with respect to the Environmental Assessment (EA) glass in terms of durability as defined by the Product Consistency Test (PCT). To support programmatic objectives, twenty-eight SB7a glasses were selected based on the nominal sludge projections used to support the frit recommendation. Twenty-three of the SB7a VS glasses were based on the use of Frit 418, while 5 glasses were based on the use of Frit 702. Frit 702 was also identified as a viable candidate for SB7a, especially if SO{sub 4} concentrations are found to be higher than anticipated. Frit 702 has shown a higher SO{sub 4} retention capability as compared to Frit 418. With respect to acceptability, the PCT results of the SB7a-VS glasses are acceptable relative to the EA glass regardless of thermal history (quenched or canister centerline cooled) or compositional view (target or measured). More specifically, all of the SB7a glasses have normalized boron release values (NL [B]) less than 0.9 g/L as compared to the benchmark NL [B] value for EA of 16.695 g/L. With respect to the applicability of the current durability models to the SB7a VS compositional region of interest, all of the study glasses (based on target compositions) lie within the 95% confidence intervals of the model predictions. When model applicability is based on the measured compositions, all of the SB7a VS glasses are predictable with the exception of SB7aVS-02 and SB7aVS-06. Although the NL [B] values of these two glasses range from 0.66 to 0.73 g/L (considered very acceptable), the PCT responses are not considered predictable by the current durability models. The current durability models are conservative for these glasses since they are more durable than predicted by the models. These two glasses are extreme vertices (EV) based compositions coupled with Frit 418 at 36% WL and target the maximum Na{sub 2}O content (15.01 wt% Na{sub 2}O) of the SB7a VS glasses. Higher alkali glasses for which the model overpredicts the PCT response have been observed previously in the Sludge Batch 3 (SB3) Phase 1 VS and the Sludge Batch 6 (SB6) VS.