New Measurements of the Transverse Beam Asymmetry for Elastic Electron Scattering from Selected Nuclei
Not Available
Abrahamyan, S.↗
Engineering topics
Lambert, D
Publications and source records attributed to Lambert, D.
SLUDGE BATCH 7B QUALIFICATION ACTIVITIES WITH SRS TANK FARM SLUDGE
Waste Solidification Engineering (WSE) has requested that characterization and a radioactive demonstration of the next batch of sludge slurry - Sludge Batch 7b (SB7b) - be completed in the Shielded Cells Facility of the Savannah River National Laboratory (SRNL) via a Technical Task Request (TTR). This characterization and demonstration, or sludge batch qualification process, is required prior to transfer of the sludge from Tank 51 to the Defense Waste Processing Facility (DWPF) feed tank (Tank 40). The current WSE practice is to prepare sludge batches in Tank 51 by transferring sludge from other tanks. Discharges of nuclear materials from H Canyon are often added to Tank 51 during sludge batch preparation. The sludge is washed and transferred to Tank 40, the current DWPF feed tank. Prior to transfer of Tank 51 to Tank 40, SRNL typically simulates the Tank Farm and DWPF processes with a Tank 51 sample (referred to as the qualification sample). With the tight schedule constraints for SB7b and the potential need for caustic addition to allow for an acceptable glass processing window, the qualification for SB7b was approached differently than past batches. For SB7b, SRNL prepared a Tank 51 and a Tank 40 sample for qualification. SRNL did not receive the qualification sample from Tank 51 nor did it simulate all of the Tank Farm washing and decanting operations. Instead, SRNL prepared a Tank 51 SB7b sample from samples of Tank 7 and Tank 51, along with a wash solution to adjust the supernatant composition to the final SB7b Tank 51 Tank Farm projections. SRNL then prepared a sample to represent SB7b in Tank 40 by combining portions of the SRNL-prepared Tank 51 SB7b sample and a Tank 40 Sludge Batch 7a (SB7a) sample. The blended sample was 71% Tank 40 (SB7a) and 29% Tank 7/Tank 51 on an insoluble solids basis. This sample is referred to as the SB7b Qualification Sample. The blend represented the highest projected Tank 40 heel (as of May 25, 2011), and thus, the highest projected noble metals content for SB7b. Characterization was performed on the Tank 51 SB7b samples and SRNL performed DWPF simulations using the Tank 40 SB7b material. This report documents: (1) The preparation and characterization of the Tank 51 SB7b and Tank 40 SB7b samples. (2) The performance of a DWPF Chemical Process Cell (CPC) simulation using the SB7b Tank 40 sample. The simulation included a Sludge Receipt and Adjustment Tank (SRAT) cycle, where acid was added to the sludge to destroy nitrite and reduce mercury, and a Slurry Mix Evaporator (SME) cycle, where glass frit was added to the sludge in preparation for vitrification. The SME cycle also included replication of five canister decontamination additions and concentrations. Processing parameters were based on work with a nonradioactive simulant. (3) Vitrification of a portion of the SME product and characterization and durability testing (as measured by the Product Consistency Test (PCT)) of the resulting glass. (4) Rheology measurements of the SRAT receipt, SRAT product, and SME product. This program was controlled by a Task Technical and Quality Assurance Plan (TTQAP), and analyses were guided by an Analytical Study Plan. This work is Technical Baseline Research and Development (R&D) for the DWPF. It should be noted that much of the data in this document has been published in interoffice memoranda. The intent of this technical report is bring all of the SB7b related data together in a single permanent record and to discuss the overall aspects of SB7b processing.
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DEMONSTRATION OF THE GLYCOLIC-FORMIC FLOWSHEET IN THE SRNL SHIELDED CELLS USING ACTUAL WASTE
Glycolic acid was effective at dissolving many metals, including iron, during processing with simulants. Criticality constraints take credit for the insolubility of iron during processing to prevent criticality of fissile materials. Testing with actual waste was needed to determine the extent of iron and fissile isotope dissolution during Chemical Process Cell (CPC) processing. The Alternate Reductant Project was initiated by the Savannah River Remediation (SRR) Company to explore options for the replacement of the nitric-formic flowsheet used for the CPC at the Defense Waste Processing Facility (DWPF). The goals of the Alternate Reductant Project are to reduce CPC cycle time, increase mass throughput of the facility, and reduce operational hazards. In order to achieve these goals, several different reductants were considered during initial evaluations conducted by Savannah River National Laboratory (SRNL). After review of the reductants by SRR, SRNL, and Energy Solutions (ES) Vitreous State Laboratory (VSL), two flowsheets were further developed in parallel. The two flowsheet options included a nitric-formic-glycolic flowsheet, and a nitric-formic-sugar flowsheet. As of July 2011, SRNL and ES/VSL have completed the initial flowsheet development work for the nitric-formic-glycolic flowsheet and nitric-formic-sugar flowsheet, respectively. On July 12th and July 13th, SRR conducted a Systems Engineering Evaluation (SEE) to down select the alternate reductant flowsheet. The SEE team selected the Formic-Glycolic Flowsheet for further development. Two risks were identified in SEE for expedited research. The first risk is related to iron and plutonium solubility during the CPC process with respect to criticality. Currently, DWPF credits iron as a poison for the fissile components of the sludge. Due to the high iron solubility observed during the flowsheet demonstrations with simulants, it was necessary to determine if the plutonium in the radioactive sludge slurry demonstrated the same behavior. The second risk is related to potential downstream impacts of glycolate on Tank Farm processes. The downstream impacts will be evaluated by a separate research team. Waste Solidification Engineering (WSE) has requested a radioactive demonstration of the Glycolic-Formic Flowsheet with radioactive sludge slurry be completed in the Shielded Cells Facility of the SRNL. The Shielded Cells demonstration only included a Sludge Receipt and Adjustment Tank (SRAT) cycle, and not a Slurry Mix Evaporator (SME) cycle or the co-processing of salt products. Sludge Batch 5 (SB5) slurry was used for the demonstration since it was readily available, had been previously characterized, and was generally representative of sludges being processing in DWPF. This sample was never used in the planned Shielded Cells Run 7 (SC-7).
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IMPACT OF THE SMALL COLUMN ION EXCHANGE PROCESS ON THE DEFENSE WASTE PROCESSING FACILITY - 12112
The Savannah River Site (SRS) is investigating the deployment of a parallel technology to the Salt Waste Processing Facility (SWPF, presently under construction) to accelerate high activity salt waste processing. The proposed technology combines large waste tank strikes of monosodium titanate (MST) to sorb strontium and actinides with two ion exchange columns packed with crystalline silicotitanate (CST) resin to sorb cesium. The new process was designated Small Column Ion Exchange (SCIX), since the ion exchange columns were sized to fit within a waste storage tank riser. Loaded resins are to be combined with high activity sludge waste and fed to the Defense Waste Processing Facility (DWPF) for incorporation into the current glass waste form. Decontaminated salt solution produced by SCIX will be fed to the SRS Saltstone Facility for on-site immobilization as a grout waste form. Determining the potential impact of SCIX resins on DWPF processing was the basis for this study. Accelerated salt waste treatment is projected to produce a significant savings in the overall life cycle cost of waste treatment at SRS.
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GLYCOLIC-FORMIC ACID FLOWSHEET SLUDGE MATRIX STUDY
Testing was completed to demonstrate the viability of the newly developed glycolic acid/formic acid flowsheet on processing in the Defense Waste Processing Facility's (DWPF) Chemical Process Cell (CPC). The Savannah River National Laboratory (SRNL) initiated a sludge matrix study to evaluate the impact of changing insoluble solid composition on the processing characteristics of slurries in DWPF. Four sludge simulants were prepared to cover two compositional ranges in the waste. The first was high iron/low aluminum versus low iron/high aluminum (referred to as HiFe or LoFe in this report). The second was high calcium-manganese/low nickel, chromium, and magnesium versus low calcium-manganese/high nickel, chromium, and magnesium (referred to as HiMn or LoMn in this report). These two options can be combined to form four distinct sludge compositions. The sludge matrix study called for testing each of these four simulants near the minimum acid required for nitrite destruction (100% acid stoichiometry) and at a second acid level that produced significant hydrogen by noble metal catalyzed decomposition of formic acid (150% acid stoichiometry). Four simulants were prepared based on the four possible combinations of the Al/Fe and Mn-Ca/Mg-Ni-Cr options. Preliminary simulant preparation work has already been documented. The four simulants were used for high and low acid testing. Eight planned experiments (GF26 to GF33) were completed to demonstrate the viability of the glycolic-formic flowsheet. Composition and physical property measurements were made on the SRAT product. Composition measurements were made on the condensate from the Mercury Water Wash Tank (MWWT), Formic Acid Vent Condenser (FAVC), ammonia scrubber and on SRAT samples pulled throughout the SRAT cycle. Updated values for formate loss and nitrite-tonitrate conversion were found that can be used in the acid calculations for future sludge matrix process simulations with the glycolic acid/formic acid flowsheet. Preliminary results of the initial testing indicate: (1) Hydrogen generation rate was very low throughout all SRAT cycles. (2) The mercury concentration of the SRAT product was below the 0.8 wt% limit in all runs. (3) Nitrite in the SRAT product was <100 mg/kg for all runs. (4) Foaminess was not an issue using the nominal antifoam addition strategy in these tests. (5) The high aluminum sludges (LoFe, HM type sludges) were much more viscous than the Hi Fe sludges. At 100% acid stoichiometry, the SRAT products from the high aluminum sludges were very viscous but at 150% acid stoichiometry, the SRAT products from the high aluminum sludges were very thin. This makes the glycolic acid/formic acid flowsheet an improvement for processing more viscous sludges. (6) The pH of the SRAT products was from 2.7-3.1 for the 150% acid stoichiometry runs and 5.1-6.1 for the 100% acid stoichiometry runs, significantly lower than is typical of the baseline nitric acid/formic acid flowsheet.
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GLYCOLIC ACID PHYSICAL PROPERTIES, IMPURITIES, AND RADIATION EFFECTS ASSESSMENT
The Defense Waste Processing Facility (DWPF) is pursuing alternative reductants/flowsheets to increase attainment to meet closure commitment dates. In fiscal year 2009, SRNL evaluated several options and recommended the further assessment of the nitric/formic/glycolic acid flowsheet. SRNL is currently performing testing with this flowsheet to support the DWPF down-select of alternate reductants. As part of the evaluation, SRNL was requested to determine the physical properties of formic and glycolic acid blends. Blends of formic acid in glycolic acid were prepared and their physical properties tested. Increasing amounts of glycolic acid led to increases in blend density, viscosity and surface tension as compared to the 90 wt% formic acid that is currently used at DWPF. These increases are small, however, and are not expected to present any difficulties in terms of processing. The effect of sulfur impurities in technical grade glycolic acid was studied for its impact on DWPF glass quality. While the glycolic acid specification allows for more sulfate than the current formic acid specification, the ultimate impact is expected to be on the order of 0.03 wt% sulfur in glass. Note that lower sulfur content glycolic acid could likely be procured at some increased cost if deemed necessary. A paper study on the effects of radiation on glycolic acid was performed. The analysis indicates that substitution of glycolic acid for formic acid would not increase the radiolytic production rate of H{sub 2} and cause an adverse effect in the SRAT or SME process. It has been cited that glycolic acid solutions that are depleted of O{sub 2} when subjected to large radiation doses produced considerable quantities of a non-diffusive polymeric material. Considering a constant air purge is maintained in the SRAT and the solution is continuously mixed, oxygen depletion seems unlikely, however, if this polymer is formed in the SRAT solution, the rheology of the solution may be affected and pumping of the solution may be hindered. However, an irradiation test with a simulated SRAT product supernate containing glycolic acid in an oxygen depleted atmosphere found no evidence of polymerization.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
GLYCOLIC-FORMIC ACID FLOWSHEET FINAL REPORT FOR DOWNSELECTION DECISION
Flowsheet testing was performed to develop the nitric-glycolic-formic acid flowsheet (referred to as the glycolic-formic flowsheet throughout the rest of the report) as an alternative to the nitric/formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be removed in the Sludge Receipt and Adjustment Tank (SRAT) with minimal hydrogen generation. All processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Forty-six runs were performed in total, including the baseline run and the melter feed preparation runs. Significant results are summarized. The baseline nitric/formic flowsheet run, using the SB6 simulant produced by Harrell was extremely difficult to process successfully under existing DWPF acceptance criteria with this simulant at the HM levels of noble metals. While nitrite was destroyed and mercury was removed to near the DWPF limit, the rheology of the SRAT and SME products were well above design basis and hydrogen generation far exceeded the DWPF SRAT limit. In addition, mixing during the SME cycle was very poor. In this sense, the nitric/glycolic/formic acid flowsheet represents a significant upgrade over the current flowsheet. Mercury was successfully removed with almost no hydrogen generation and the SRAT and SME products yield stresses were within process limits or previously processed ranges. The glycolic-formic flowsheet has a very wide processing window. Testing was completed from 100% to 200% of acid stoichiometry and using a glycolic-formic mixture from 40% to 100% glycolic acid. The testing met all processing requirements throughout these processing windows. This should allow processing at an acid stoichiometry of 100% and a glycolic-formic mixture of 80% glycolic acid with minimal hydrogen generation. It should also allow processing endpoints in the SRAT and SME at significantly higher total solids content and may be effective at acid stoichiometries below 100%, although no testing was performed below 100% acid stoichiometry. There are several issues related to the development of the glycolic-formic flowsheet. First, the measurement of anions using the new glycolate anion procedure likely needs to be optimized to improve the accuracy of the anions important to DWPF processing and REDOX prediction. Second, the existing REDOX equation with an added term for glycolate did not accurately predict the glass REDOX for the glycolic-formic flowsheet. Improvement of the anion measurement or modification of the REDOX methodology or equation may be necessary to improve the REDOX prediction. Last, the glycolic-formic flowsheet dissolves a number of metals, including iron. This leads to a thinner slurries but also dissolves up a portion of the iron, which is currently used for criticality control. It is recommended that DWPF continue to support development of the glycolic-formic flowsheet. This flowsheet meets or outperforms the baseline flowsheet in off-gas generation, mercury removal, product rheology and general ease of processing. Additional testing is in progress to demonstrate the effectiveness of the nitric-glycolic-formic flowsheet in processing a wide sludge processing window using the matrix sludge simulants.
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