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At least 649 records · Page 36

Technetium Inventory, Distribution, and Speciation in Hanford Tanks

The purpose of this report is three fold: 1) assemble the available information regarding technetium (Tc) inventory, distribution between phases, and speciation in Hanford’s 177 storage tanks into a single, detailed, comprehensive assessment; 2) discuss the fate (distribution/speciation) of Tc once retrieved from the storage tanks and processed into a final waste form; and 3) discuss/document in less detail the available data on the inventory of Tc in other "pools" such as the vadose zone below inactive cribs and trenches, below single-shell tanks (SSTs) that have leaked, and in the groundwater below the Hanford Site. A thorough understanding of the inventory for mobile contaminants is key to any performance or risk assessment for Hanford Site facilities because potential groundwater and river contamination levels are proportional to the amount of contaminants disposed at the Hanford Site. Because the majority of the total 99 Tc produced at Hanford (~32,600 Ci) is currently stored in Hanford’s 177 tanks (~26,500 Ci), there is a critical need for knowledge of the fate of this 99 Tc as it is removed from the tanks and processed into a final solid waste form. Current flow sheets for the Hanford Waste Treatment and Immobilization Plant process show most of the 99 Tc will be immobilized as low-activity waste glass that will remain on the Hanford Site and disposed at the Integrated Disposal Facility (IDF); only a small fraction will be shipped to a geologic repository with the immobilized high-level waste. Past performance assessment studies, which focused on groundwater protection, have shown that 99 Tc would be the primary dose contributor to the IDF performance.

storage tanks↗

Results For the Fourth Quarter 2013 Tank 50 WAC Slurry Sample: Chemical and Radionuclide Contaminants

This report details the chemical and radionuclide contaminant results for the characterization of the 2013 Fourth Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC) in effect at that time. Information from this characterization will be used by DWPF & Saltstone Facility Engineering (DSFE) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: SRR WAC targets or limits were met for all analyzed chemical and radioactive contaminants unless noted in this section. 59 Ni, 94 Nb, 247 Cm, 249 Cf, and 251 Cf are above the requested SRR target concentrations. However, they are below the detection limits established by SRNL. Norpar 13 and Isopar L have higher detection limits compared with the Saltstone WAC. The data provided in this report is based upon the concentrations in the sub-sample, and due to the limited solubility of these materials in aqueous solution, may not represent the concentrations of the analytes in Tank 50. The low insoluble solids content increases the measurement uncertainty for insoluble species. The semivolatile organic analysis (SVOA) method employed in the measurement of Norpar 13 and tributyl phosphate (TBP) has resulted in the erroneous reporting of a variety of small chain alcohols, including 4-methyl-3-hexanol and 5-methyl-3-hexanol, in previous quarterly sample reports. It has now been determined that these alcohols are an artifact of the sample preparation. Further work is being conducted in SRNL to delineate the conditions that produce these alcohols, and these findings will be reported separately.

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Prediction of Peak Hydrogen Concentrations for Deep Sludge Retrieval in Tanks AN-101 and AN-106 from Historical Data of Spontaneous Gas Release Events

Radioactive and chemical wastes from nuclear fuel processing are stored in large underground storage tanks at the Hanford Site. The Tank Operations Contractor is continuing a program of moving solid wastes from single-shell tanks (SSTs) to double-shell tanks (DSTs) and preparing for waste feed delivery (WFD). A new mechanism for a large spontaneous gas release event (GRE) in deep sludge sediments has been postulated. The creation of this potential new GRE hazard, deep sludge gas release events (DSGREs), is the retrieval of sludge waste into a single DST that results in a sediment depth greater than operating experience has demonstrated is safe. The Tank Operations Contractor program of moving solid wastes from SSTs to DSTs and preparing for WFD is being negatively impacted by this sediment depth limit.

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Results for the Third Quarter 2013 Tank 50 WAC Slurry Sample: Chemical and Radionuclide Contaminants

This report details the chemical and radionuclide contaminant results for the characterization of the 2013 Third Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC) in effect at that time. 1 Information from this characterization will be used by DWPF & Saltstone Facility Engineering (DSFE) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: SRR WAC targets or limits were met for all analyzed chemical and radioactive contaminates unless noted in this section. 59 Ni, 94 Nb, 247 Cm, 249 Cf, and 251 Cf are above the requested SRR target concentrations. 2 However, they are below the detection limits established by SRNL. 3 Norpar 13 and Isopar L have higher detection limits4 compared with the Saltstone WAC. 1 The data provided in this report is based upon the concentrations in the sub-sample, and due to the limited solubility in aqueous solution, may not represent the concentrations of the analytes in Tank 50. Finally, the low insoluble solids content increases the measurement uncertainty for insoluble species.

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Results for the Fourth Quarter 2012 Tank 50 WAC Slurry Sample: Chemical and Radionuclide Contaminants

This report details the chemical and radionuclide contaminant results for the characterization of the 2012 Fourth Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC).1 Information from this characterization will be used by Waste Solidification Engineering (WSE) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: The concentration of the reported chemical and radioactive contaminants were less than their respective WAC Limits and Targets, unless noted in this section. Norpar 13 and Isopar L have higher detection limits 5 compared with the Saltstone WAC 1 . The data provided in this report is based upon the concentrations in the sub-sample, and due to the limited solubility in aqueous solution, may not represent the concentrations of the analytes in Tank 50. Diisooctyl adipate (or diisooctyl hexanedioate) was measured at 1.30E+00 mg/L in one of two replicate measurements conducted on an at-depth sample. a The organic analysis of the at-depth sample was conducted at the request of SRR. 4 This analyte was below the detection limit in the surface sample. The low insoluble solids content increases the measurement uncertainty for insoluble species.

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Analysis of Tank 39H (HTF-39-15-61, 62) Surface and Subsurface Supernatant Samples in Support of Corrosion Control Program

This report provides the results of analyses on Tanks 39H surface and subsurface supernatant liquid samples in support of the Corrosion Control Program. Analyses included warm acid strike preparation followed by analysis for silicon, aluminum, and sodium and water dilution preparation followed by analysis for anions. Other reported analytical results include analyses results for uranium, Pu-241 and Pu-239. The measured sodium concentration averaged, respectively, 4.28E+00 ± 9.30E-02 M and 4.32E+00 ± 1.076E-01 M in the Tank 39H surface sample and Tank 39H subsurface sample. In general, the nitrate, nitrite, free-OH and specific gravity of the Tank 39H surface and subsurface samples were all about the same in magnitude, respectively, averaging 1.98 M, 0.314 M, 1.26 M and 1.24. The measured silicon concentration for the Tank 39H surface and subsurface samples were, respectively, 3.84E+01± 5.51E+00 and 4.14E+01± 1.17E + 00 mg/L. Based on the uranium, Pu-241 and Pu-239 concentrations, the calculated U-235 equivalent is 21.41 wt% for the surface sample and 21.32 wt% for the subsurface sample.

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Alternative Chemical Cleaning Methods for High Level Waste Tanks: Simulant Studies

Solubility testing with simulated High Level Waste tank heel solids has been conducted in order to evaluate two alternative chemical cleaning technologies for the dissolution of sludge residuals remaining in the tanks after the exhaustion of mechanical cleaning and sludge washing efforts. Tests were conducted with non-radioactive pure phase metal reagents, binary mixtures of reagents, and a Savannah River Site PUREX heel simulant to determine the effectiveness of an optimized, dilute oxalic/nitric acid cleaning reagent and pure, dilute nitric acid toward dissolving the bulk non-radioactive waste components. A focus of this testing was on minimization of oxalic acid additions during tank cleaning. For comparison purposes, separate samples were also contacted with pure, concentrated oxalic acid which is the current baseline chemical cleaning reagent. In a separate study, solubility tests were conducted with radioactive tank heel simulants using acidic and caustic permanganate-based methods focused on the “targeted” dissolution of actinide species known to be drivers for Savannah River Site tank closure Performance Assessments. Permanganate-based cleaning methods were evaluated prior to and after oxalic acid contact.

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Determining the Release of Radionuclides from Tank 18F Waste Residual Solids: FY2016 Report

Pore water leaching studies were conducted on actual Savannah River Site (SRS) Tank 18F residual waste solids to support Liquid Waste tank closure efforts. A test methodology was developed during previous simulant testing to produce slurries of tank residual solids and grout-representative solids in grout pore water solutions (based on SRS groundwater compositions) with pH and E h values expected during the aging of the closed waste tank. The target conditions are provided below where the initial pore water has a reducing potential and a relatively high pH (Reducing Region II). The pore water is expected to become increasingly oxidizing with time (Oxidizing Region II) and during the latter stages of aging (Oxidizing Region III) the pH is expected to decrease. For the reducing case, tests were conducted with both unwashed and washed Tank 18F residual solids. For the oxidizing cases (Oxidizing Regions II and III), all samples were washed with simulated grout pore water solutions prior to testing, since it is expected that these conditions will occur after considerable pore water solution has passed through the system. For the reducing case, separate tests were conducted with representative ground grout solids and with calcium carbonate reagent, which is the grout phase believed to be controlling the pH. Ferrous sulfide (FeS) solids were also added to the reducing samples to lower the slurry E h value. Calcium carbonate solids were used as the grout-representative solid phase for each of the oxidizing cases. Air purge-gas with and without CO 2 removed was transferred through the oxidizing test samples and nitrogen purge-gas was transferred through the reducing test samples during leach testing. The target pH values were achieved to within 0.5 pH units for all samples. Leaching studies were conducted over an E h range of approximately 0.7 V. However, the highest and lowest E h values achieved of ~+0.5 V and ~-0.2 V were significantly less positive and less negative, respectively, than the target values. Achievement of more positive and more negative E h values is believed to require the addition of non-representative oxidants and reductants, respectively.

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Tank 22 Supernate Sample Characterization for Select Radionuclides

The Savannah River National Laboratory (SRNL) was requested by Savannah River Remediation (SRR), through a Technical Assistance Request (G-TAR-H-00007) to provide additional sample characterization on unfiltered Tank 22 supernate identified as sample HTF-22-18-117, which was delivered to SRNL Shielded Cells on December 14, 2018. A summary of the average analytical results for this unfiltered Tank 22 supernate liquid follows. The density of the unfiltered Tank 22 supernate is 1.008 g/mL, 0.2%RSD. The Tank 22 supernate sample was analyzed for a total of 45 radionuclide species, with 15 of these radionuclides showing activity levels above minimum detectable activity of at least one replicate. Cesium-137 showed the highest activity at 2.90E+07 dpm/mL, 2.35 %RSD (1.30E-02 Ci/ L) with U-235 showing the lowest measurable activity at an average of 1.66E-01 dpm/mL, 6.26 %RSD (7.49E-11 Ci/L). The primary beta emitting radionuclides in the unfiltered Tank 22 supernate sample include Sr-90, Y-90 and Cs-137 at average activity concentrations of 1.10E-05, 1.10E-05 and 1.30E-02 Ci/L, respectively. The primary gamma emitting radionuclide is Ba-137 m at an average activity concentration of 1.23E-02 Ci/L (note that the activity concentration for Ba-137 m was calculated as 94.7% the Cs-137 activity concentration).

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Characterization and CST Batch Contact Equilibrium Testing of Aged TCCR Tank 10H Batch 1A and 2 Process Supernate Samples

The Tank Closure Cesium Removal (TCCR) system uses ion exchange columns filled with Crystalline Silicotitanate (CST) media to process radioactive waste solutions for the removal of Cs-137. TCCR currently focuses on dissolving Savannah River Site (SRS) Tank 10H waste (primarily sodium saltcake solids) within the tank followed by at-tank ion exchange column treatment. Previous equilibrium batch contact tests conducted in the SRNL Shielded Cells laboratory and associated analyses indicated that CST cesium removal performance was lower than predicted by ZAM modeling for TCCR Tank 10H Production Supernate Batch 1A. An average cesium distribution coefficient of 1,948 mL/g which corresponds to 94.1% Cs + removal was observed for Batch 1A supernate at 38 °C in January of 2019 using laboratory pretreated IONSIV™ R9120-B a CST from Lot #209900034 (predominant TCCR CST batch) at a phase ratio of 122 mL/g. This cesium loading was approximately 32% lower than model predictions, presumably due to ion exchange competition or fouling associated with alkaline earth or transition metals present in the solutions at low levels. The current testing was designed to: 1) evaluate whether supernate compositional changes during storage would result in improved cesium removal performance with CST, and 2) assist in media selection and handling protocols for future TCCR columns by evaluating several CST manufacturer batches as well as samples of one CST batch which had been pretreated using two different methods (field and laboratory methods).

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Results for the Fourth Quarter Calendar Year 2020 Tank 50 Salt Solution Sample

In this Technical Report, the chemical and radionuclide contaminant results from the Fourth Quarter Calendar Year 2020 (CY20) sample of Tank 50 salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Remediation (SRR) for the transfer of aqueous waste from Tank 50 to the Saltstone Production Facility (SPF), where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) Limits and Targets. The chemical and radionuclide contaminant results from the characterization of the Fourth Quarter CY20 sampling of Tank 50 were requested by SRR personnel via a Task Technical Request (TTR) and details of the testing are presented in the Savannah River National Laboratory (SRNL) Task Technical and Quality Assurance Plan (TTQAP). This Technical Report is part of Deliverable 2 relating to Task 1 from the SRR request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals per Task 2 from the SRR request, will be obtained semi-annually for the 1QCY21 and 3QCY21 Tank 50 samples. However, data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals for this current 4QCY20 Tank 50 sample will be obtained and documented per the special analysis associated with the vault classification sample as described in the associated TTQAP.

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Tank 50 Salt Solution Sample (2QCY21)

In this Technical Report, the chemical and radionuclide contaminant results from the Second Quarter Calendar Year 2021 (CY21) sample of Tank 50 salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Remediation (SRR) for the transfer of aqueous waste from Tank 50 to the Saltstone Production Facility (SPF), where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) Limits and Targets that were established at the time the Tank 50 sample was obtained. The chemical and radionuclide contaminant results from the characterization of the Second Quarter CY21 sampling of Tank 50 were requested by SRR personnel via a Task Technical Request (TTR) and details of the testing are presented in the Savannah River National Laboratory (SRNL) Task Technical and Quality Assurance Plan (TTQAP). This Technical Report is part of Deliverable 2 relating to Task 1 from the SRR request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals per Task 2 from the SRR request, will be obtained semi-annually for the 1QCY21 and 3QCY21 Tank 50 samples.

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Results for the Third Quarter Calendar Year 2021 Tank 50 Salt Solution Sample

In this Technical Report, the chemical and radionuclide contaminant results from the Third Quarter Calendar Year 2021 (CY21) sample of Tank 50 salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Remediation (SRR) for the transfer of aqueous waste from Tank 50 to the Saltstone Production Facility (SPF), where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) Limits and Targets that were established at the time the Tank 50 sample was obtained. The chemical and radionuclide contaminant results from the characterization of the Third Quarter CY21 sampling of Tank 50 were requested by SRR personnel via a Task Technical Request (TTR) and details of the testing are presented in the Savannah River National Laboratory (SRNL) Task Technical and Quality Assurance Plan (TTQAP). This Technical Report is part of Deliverable 2 relating to Task 1 from the SRR request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals per Task 2 from the SRR request, will be obtained semi-annually for the 1QCY21 and 3QCY21 Tank 50 samples.

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Results for the Second Quarter Calendar Year 2021 Tank 50 Salt Solution Sample

In this Technical Report, the chemical and radionuclide contaminant results from the Second Quarter Calendar Year 2021 (CY21) sample of Tank 50 salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Remediation (SRR) for the transfer of aqueous waste from Tank 50 to the Saltstone Production Facility (SPF), where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) Limits and Targets that were established at the time the Tank 50 sample was obtained. The chemical and radionuclide contaminant results from the characterization of the Second Quarter CY21 sampling of Tank 50 were requested by SRR personnel via a Task Technical Request (TTR) and details of the testing are presented in the Savannah River National Laboratory (SRNL) Task Technical and Quality Assurance Plan (TTQAP). This Technical Report is part of Deliverable 2 relating to Task 1 from the SRR request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals per Task 2 from the SRR request, will be obtained semi-annually for the 1QCY21 and 3QCY21 Tank 50 samples.

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Results for the January 2022 Semiannual Tank 50 Salt Solution Sample

In this Technical Report, the chemical and radionuclide contaminant results from the January 2022 Semiannual sample of Tank 50 salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Mission Completion (SRMC) for the transfer of aqueous waste from Tank 50 to the Saltstone Production Facility (SPF), where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) LIMITS and TARGETS that were established at the time the Tank 50 sample was obtained. The chemical and radionuclide contaminant results from the characterization of the January 2022 semiannual sampling of Tank 50 were requested by SRMC personnel via a Task Technical Request (TTR) and details of the testing are presented in the Savannah River National Laboratory (SRNL) Task Technical and Quality Assurance Plan (TTQAP). This Technical Report is part of Deliverable 2 relating to Task 1 from the SRMC request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals per Task 2 from the RMC request, will be obtained semiannually for the January 2022 and July 2022 Tank 50 samples.

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Results for the July 2022 Semiannual Tank 50 Salt Solution Sample

In this Technical Report, the chemical and radionuclide contaminant results from the July 2022 Semiannual sample of Tank 50 salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Mission Completion (SRMC) for the transfer of aqueous waste from Tank 50 to the Saltstone Production Facility (SPF), where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) LIMITS and TARGETS that were established at the time the Tank 50 sample was obtained. The chemical and radionuclide contaminant results from the characterization of the July 2022 semiannual sampling of Tank 50 were requested by SRMC personnel via a Task Technical Request (TTR) and details of the testing are presented in the Savannah River National Laboratory (SRNL) Task Technical and Quality Assurance Plan (TTQAP). This Technical Report is part of Deliverable 2 relating to Task 1 from the SRMC request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals per Task 2 from the SRMC request, will be obtained semiannually for the January 2022 and July 2022 Tank 50 samples.

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Design and Materials of Reference Electrodes for Radioactive Waste Tank Service – A Literature Review

The Hanford site stores approximately 55 million gallons of radioactive and chemically hazardous wastes from the production of weapons materials. The wastes are stored in 177 underground, carbon steel storage tanks, 149 of these are single shell tanks (SSTs) and 28 of these are double shell tanks (DSTs). The DSTs provide critical retrieval and interim storage before the waste is vitrified in the Waste Treatment and Isolation Plant (WTP). The DSTs have been in service for 38 to 56 years and current plans indicate that WTP operations will be completed in 2075. Thus, the tanks will need to remain in service far beyond the initial 40-year life expectancy. For life extension of the tanks, effective corrosion control practices must remain in force. This effort includes direct measurements of the extent of corrosion (e.g., ultrasonic measurements and corrosion coupons) and electrochemical processes (e.g., linear polarization measurements).

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Tank 48H Phase 1 Initial Testing Using Sodium Permanganate to Decompose Tetraphenylborate: Simulant Studies with Shaker Oven and 2-L Vessel

Tank 48H currently holds legacy material including organic tetraphenylborate (TPB) compounds from the operation of the In-Tank Precipitation process. The large quantity of TPB is not compatible with the waste treatment facilities at SRS and must be removed or undergo treatment to oxidize the organic compounds before the tank can be returned to routine Tank Farm service. Tank 48H currently holds approximately 270,000 gallons of legacy material comprised of decontaminated salt solution, approximately 20,000 kilograms of TPB solids, 3,400 kilograms of sludge solids, and 1,800 kilograms of monosodium titanate (MST).

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