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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

In-service inspection of radioactive waste tanks at the Savannah River Site - 15410

Liquid radioactive wastes from the Savannah River Site (SRS) separation process are stored in large underground carbon steel tanks. The high level wastes are processed in several of the tanks and then transferred by piping to other site facilities for further processing before they are stabilized in a vitrified or grout waste form. Based on waste removal and processing schedules, many of the tanks, will be required to be in service for times exceeding the initial intended life. Until the waste is removed from storage, transferred, and processed, the materials and structures of the tanks must maintain a confinement function by providing a barrier to the environment and by maintaining acceptable structural stability during design basis events, which include loadings from both normal service and abnormal (e.g., earthquake) conditions. A structural integrity program is in place to maintain the structural and leak integrity functions of these waste tanks throughout their intended service life. In-service inspection (ISI) is an essential element of a comprehensive structural integrity program for the waste tanks at the Savannah River Site (SRS). The ISI program was developed to determine the degree of degradation the waste tanks have experienced due to service conditions. As a result of the inspections, an assessment can be made of the effectiveness of corrosion controls for the waste chemistry, which precludes accelerated localized and general corrosion of the waste tanks. Ultrasonic inspections (UT) are performed to detect and quantify the degree of general wall thinning, pitting and cracking as a measure of tank degradation. The results from these inspections through 2013, for the 27 Type III/IIIA tanks, indicate no reportable in-service corrosion degradation in the primary tank (i.e., general, pitting, or cracking). The average wall thickness for all tanks remains above the manufactured nominal thickness minus 0.25 millimeter and the largest pit identified is approximately 1.70 millimeter deep (i.e., less than 10% through-wall). Improvements to the inspection program were recently instituted to provide additional confidence in the degradation rates. Thickness measurements from a single vertical strip along the accessible height of the primary tank have been used as a baseline to compare historical measurements. Changes in wall thickness and pit depths along this vertical strip are utilized to estimate the rate of corrosion degradation. An independent review of the ISI program methodology, results, and path forward was held in August 2009. The review recommended statistical sampling of the tanks to improve the confidence of the single strip inspection program. The statistical sampling plan required that SRS increase the amount of area scanned per tank. Therefore, in addition to the baseline vertical strip that is obtained for historical comparisons, four additional randomly selected vertical strips are inspected. To date, a total of 104 independent vertical strips along the height of the primary tank have been completed. A statistical analysis of the data indicates that at this coverage level there is a 99.5% confidence level that one of the worst 5% of all the vertical strips was inspected. That is, there is a relatively high likelihood that the SRS inspection program has covered one of the most corroded areas of any of the Type III/IIIA waste tanks. These data further support the conclusion that there are no significant indications of wall thinning or pitting. Random sampling will continue to increase the confidence that one of the worst 5% has been inspected. In order to obtain the additional vertical strips, and minimize budget and schedule impacts, data collection speed for the UT system was optimized. Prior to 2009, the system collected data at a rate of 32 square centimeters per minute. The scan rate was increased to 129 - 160 square centimeters per minute by increasing the scanner step and pixel sizes in the data acquisition set-up. Laboratory testing was utilized to optimize the scan index/pixel size such that the requirements for wall thinning and pit detection were still maintained. SRS continues to evaluate improvements to ultrasonic equipment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Hanford Double Shell Tank Integrity Inspection - Integration of Customized Robotics - 18400

28 steel, double-shell, million gallon waste storage tanks located at the Hanford site in Washington State store both radioactive and hazardous waste. To monitor their condition and ensure continued viability, these tanks are inspected periodically through a comprehensive integrity program. In 2012, the first leak in a double-shell tank at Hanford was discovered in the 241-AY tank farm (Tank AY-102) and the failure was observed to be from the primary tank bottom. However, the exact failure location and damage mechanism have not been determined. A decision was made to pursue the capability to inspect the primary tank bottom region in order to provide additional tank integrity information. This work is particularly challenging due to the confined space in the double-shell tank annulus region (i.e. the 30 inch space between the primary and secondary tank shells), the limited dimensions of the tank risers that provide access to the annulus space (risers as small as 10 inches in diameter), and also the very small dimensions of the air channels in the concrete refractory pad that the primary waste storage tank rests on (channels are approximately two inches in diameter). Veolia Nuclear Solutions, along with Key Subcontractor Inuktun, were contracted to provide the capability to conduct these tank inspections in support of Hanford's double-shell tank integrity program. The Veolia Nuclear Solutions /Inuktun team designed, built, tested and delivered a tethered miniature robotic crawler system that utilizes the marsupial approach - a larger deployment crawler positions a smaller inspection crawler. The deployment crawler is installed via the tank riser, is magnetically coupled to the side of the tank shell, and drives to the selected deployment location at the end of one of the refractory channels where the small inspection robot is subsequently deployed. Operation of the equipment is controlled from a trailer outside the tank farm (a distance of several hundred feet). The system design includes a custom mechanism that provides for positioning and cable handling as well as the controls interface (laptop connected via control cables). The solution leveraged the Veolia Nuclear Solutions/Inuktun team's experience with delivering similar modular systems for other US and international sites. This simple but innovative solution delivered on an accelerated project schedule underlines the ability to provide effective robotic solutions to the nuclear industry. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Double-Shell Tank Primary Bottom Inspection Development - 19067

Double-Shell Tank (DST) integrity at Hanford is maintained with a variety of activities such as ultrasonic and visual inspections, chemistry controls, corrosion monitoring and structural analyses methods [1]. A pressing need for the Double-Shell Tank Integrity Program is the ability to inspect the bottom of the tanks. Though the DSTs' annulus spaces (the space between the internal and external tank walls) have been inspected visually since 1992 and with Ultrasonic Testing (UT) since 1996, WRPS has been unable to conduct inspections of the tank bottoms due to limitations of available technology, omitting about 40 percent of the tank surface below the maximum fill level from routine inspection. Visual inspections of the tank annulus have been conducted up to five times in some DSTs and the annulus space for all of the DSTs has been inspected twice with UT. The annulus region includes the walls of the primary tank and secondary liner along with accessible portions of the secondary liner bottom. Due to the lack of under-tank inspection technology, degradation of the primary tank bottom in Tank AY-102 was undetected until the tank leaked into its annulus space, confirmed in 2012 [2]. Since that time, WRPS has been working with the nondestructive examination community and the Pacific Northwest National Laboratory to evaluate potential technologies to conduct these challenging remote inspections. Recent work has included the development, testing, and deployment of several remote visual inspection technologies to observe the condition of the primary tank bottom of the DSTs by leveraging air distribution slots in the refractory pad on which it rests. Robotic solutions to conduct this inspection were developed with a detailed understanding of the physical configuration and operational logistics. Understanding and subsequent communication of these details to vendors within the robotics and nondestructive examination community was a critical component to the successful production of these new tools. In total, two remote visual inspection tools were produced by two vendors. The first tool was designed to leverage existing ultrasonic testing magnetic wall crawler technology in use within the double-shell tank annuli at Hanford. This resulted in a cost savings, immediate familiarization with the equipment, and a more streamlined shop to field experience. The second tool was developed from the ground up, and represents a more tailored and purpose-built solution to the problem. While costlier and more complex, it is also more versatile and capable of future growth or adaptation. Initial design of both tools began in early FY17 with fabrication and testing completed in early FY18. The tools were designed to be deployed alongside existing inspection operations and expand coverage. Development of visual inspection tools to evaluate the primary tank bottom region of the double-shell tanks was planned as the first stage of inspection. Continued development of volumetric sensors and incorporation of these inspection tools into Hanford's ongoing Double-Shell Tank Integrity Program are the next steps, continuously seeking to expand understanding of asset integrity and remaining useful life. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1999

Conformal Cryogenic Tank Trade Study for Reusable Launch Vehicles

Future reusable launch vehicles may be lifting bodies with non-circular cross section like the proposed Lockheed-Martin VentureStar(tm). Current designs for the cryogenic tanks of these vehicles are dual-lobed and quad-lobed tanks which are packaged more efficiently than circular tanks, but still have low packaging efficiencies with large gaps existing between the vehicle outer mold line and the outer surfaces of the tanks. In this study, tanks that conform to the outer mold line of a non-circular vehicle were investigated. Four structural concepts for conformal cryogenic tanks and a quad-lobed tank concept were optimized for minimum weight designs. The conformal tank concepts included a sandwich tank stiffened with axial tension webs, a sandwich tank stiffened with transverse tension webs, a sandwich tank stiffened with rings and tension ties, and a sandwich tank stiffened with orthogrid stiffeners and tension ties. For each concept, geometric parameters (such as ring frame spacing, the number and spacing of tension ties or webs, and tank corner radius) and internal pressure loads were varied and the structure was optimized using a finite-element-based optimization procedure. Theoretical volumetric weights were calculated by dividing the weight of the barrel section of the tank concept and its associated frames, webs and tension ties by the volume it circumscribes. This paper describes the four conformal tank concepts and the design assumptions utilized in their optimization. The conformal tank optimization results included theoretical weights, trends and comparisons between the concepts, are also presented, along with results from the optimization of a quad-lobed tank. Also, the effects of minimum gauge values and non-optimum weights on the weight of the optimized structure are described in this paper.

Rivers, H. Kevin↗
NASA NTRS2007

Runtime and Pressurization Analyses of Propellant Tanks

Multi-element unstructured CFD has been utilized at NASA SSC to carry out analyses of propellant tank systems in different modes of operation. The three regimes of interest at SSC include (a) tank chill down (b) tank pressurization and (c) runtime propellant draw-down and purge. While tank chill down is an important event that is best addressed with long time-scale heat transfer calculations, CFD can play a critical role in the tank pressurization and runtime modes of operation. In these situations, problems with contamination of the propellant by inclusion of the pressurant gas from the ullage causes a deterioration of the quality of the propellant delivered to the test article. CFD can be used to help quantify the mixing and propellant degradation. During tank pressurization under some circumstances, rapid mixing of relatively warm pressurant gas with cryogenic propellant can lead to rapid densification of the gas and loss of pressure in the tank. This phenomenon can cause serious problems during testing because of the resulting decrease in propellant flow rate. With proper physical models implemented, CFD can model the coupling between the propellant and pressurant including heat transfer and phase change effects and accurately capture the complex physics in the evolving flowfields. This holds the promise of allowing the specification of operational conditions and procedures that could minimize the undesirable mixing and heat transfer inherent in propellant tank operation. It should be noted that traditional CFD modeling is inadequate for such simulations because the fluids in the tank are in a range of different sub-critical and supercritical states and elaborate phase change and mixing rules have to be developed to accurately model the interaction between the ullage gas and the propellant. We show a typical run-time simulation of a spherical propellant tank, containing RP-1 in this case, being pressurized with room-temperature nitrogen at 540 R. Nitrogen, shown in blue on the right-hand side of the figures, enters the tank from the diffuser at the top of the figures and impinges on the RP-1, shown in red, while the propellant is being continuously drained at the rate of 1050 lbs/sec through a pipe at the bottom of the tank. The sequence of frames in Figure 1 shows the resultant velocity fields and mixing between nitrogen and RP-1 in a cross-section of the tank at different times. A vortex is seen to form in the incoming nitrogen stream that tends to entrain propellant, mixing it with the pressurant gas. The RP-1 mass fraction contours in Figure 1 are also indicative of the level of mixing and contamination of the propellant. The simulation is used to track the propagation of the pure propellant front as it is drawn toward the exit with the evolution of the mixing processes in the tank. The CFD simulation modeled a total of 10 seconds of run time. As is seen from Figure 1d, after 5.65 seconds the propellant front is nearing the drain pipe, especially near the center of the tank. Behind this pure propellant front is a mixed fluid of compromised quality that would require the test to end when it reaches the exit pipe. Such unsteady simulations provide an estimate of the time that a high-quality propellant supply to the test article can be guaranteed at the modeled mass flow rate. In the final paper, we will discuss simulations of the LOX and propellant tanks at NASA SSC being pressurized by an inert ullage. Detailed comparisons will be made between the CFD simulations and lower order models as well as with test data. Conditions leading to cryo collapse in the tank will also be identified.

Field, Robert E.↗
NASA NTRS2009

Assemblies of Conformal Tanks

Assemblies of tanks having shapes that conform to each other and/or conform to other proximate objects have been investigated for use in storing fuels and oxidizers in small available spaces in upper stages of spacecraft. Such assemblies might also prove useful in aircraft, automobiles, boats, and other terrestrial vehicles in which space available for tanks is limited. The basic concept of using conformal tanks to maximize the utilization of limited space is not new in itself: for example, conformal tanks are used in some automobiles to store windshield -washer liquid and coolant that overflows from radiators. The novelty of the present development lies in the concept of an assembly of smaller conformal tanks, as distinguished from a single larger conformal tank. In an assembly of smaller tanks, it would be possible to store different liquids in different tanks. Even if the same liquid were stored in all the tanks, the assembly would offer an advantage by reducing the mechanical disturbance caused by sloshing of fuel in a single larger tank: indeed, the requirement to reduce sloshing is critical in some applications. The figure shows a prototype assembly of conformal tanks. Each tank was fabricated by (1) copper plating a wax tank mandrel to form a liner and (2) wrapping and curing layers of graphite/epoxy composite to form a shell supporting the liner. In this case, the conformal tank surfaces are flat ones where they come in contact with the adjacent tanks. A band of fibers around the outside binds the tanks together tightly in the assembly, which has a quasi-toroidal shape. For proper functioning, it would be necessary to maintain equal pressure in all the tanks.

DeLay, Tom↗
NASA NTRS2010

Developing NDE Techniques for Large Cryogenic Tanks - Year 2 Report

The Shuttle Program requires very large cryogenic ground storage tanks in which to store liquid oxygen and hydrogen. The existing Launch Complex-39 Pad tanks, which will be passed onto future launch programs, are over 40 years old and have received minimal refurbishment and only external inspections over the years. The majority of the structure is inaccessible without a full system drain of cryogenic liquid and insulation in the annular region. It was previously thought that there was a limit to the number of temperature cycles that the tanks could handle due to possible insulation compaction before undergoing a costly and time consuming complete overhaul; therefore the tanks were not drained and performance issues with these tanks, specifically the Pad B LH2 tank, were accepted. There is a need and an opportunity, as the Shuttle program ends and work to upgrade the launch pad progresses, to develop innovative non-destructive evaluation (NDE) techniques to analyze the current tanks. Techniques are desired that can aid in determining the extent of refurbishment required to keep the tanks in service for another 20+ years. A non-destructive technique would also be a significant aid in acceptance testing of new and refurbished tanks, saving significant time and money, if corrective actions can be taken before cryogen is introduced to the systems. Year one of this project concentrated on analysis of the current tanks located at LC-39 while cryogen was present. Year two of this project concentrated on analysis of detectable thermal variations on the outer surface of the tanks as the cryogen was drained and the inner vessel warmed to ambient conditions. Two techniques have been deployed in the field to monitor the tank. The first consisted of a displacement sensor to monitor for any expansions at the base of the tank during warm-up that could indicate a compaction issue with the insulation. The second technique was continued thermal monitoring of the tank through and after warm up. The indications noted in the thermal images were compared to bore-scope images of the annular region taken once the tank was inert and warmed to ambient conditions. Similar thermal imaging was performed on a smaller tank where an insulation void was induced to compare the effectiveness of thermal imagining on a different tank geometry.

Arens, Ellen↗
DOE OSTI2020

Assessment of the Corrosion Risks to a Double Shell Tank During the Selective Removal of a Cesium-rich Supernate Layer - 20227

The Direct Feed Low Activity Waste (DF-LAW) activity will provide the initial feed to the Waste Treatment and Immobilization Plant at the Hanford Tank Farm facility. Feed preparation for DF-LAW will be carried out in multiple double shell waste tanks (DST) utilizing the Tank Side Cesium Removal (TSCR) process. Tank AP-106 will be an integral part of the TSCR process and hence key to the DFLAW activity. Prior to being utilized for this purpose, the Cs-137 concentration levels in the AP-106 supernate must be reduced significantly. The AP-106 re-purposing process manages normal waste tank addition procedures such that waste acceptance criteria objectives for Cs-137 removal are achieved. As this process was being developed, several concerns regarding tank integrity during and after repurposing of Tank AP-106, and the associated tanks (i.e., AP-102, AN-101, and AP-108), were addressed. The potential corrosion degradation mechanisms identified based on process knowledge included: general and pitting corrosion, caustic stress corrosion cracking, concentration cell corrosion, and microbiologically induced corrosion (MIC). A systematic approach was undertaken to assess the risk of corrosion during the AP-106 re-purposing process. The assessment considered the initial and present condition of the tank, the service history of the tank, the environmental conditions created in each tank during each stage of the process, process timing, and corrosion testing and modeling that approximated tank conditions. Based on this information, recommendations were provided to minimize the exposure of the tank to corrosive conditions. These recommendations included time limits for each stage of the process, staging of corrosion inhibitor solutions should process delays occur, and waste sampling with potential chemistry adjustments at defined steps in the process. Additionally, recommendations for post-process supernate chemistry adjustments and tank inspections were put forth. The greatest risk for this process occurs during the manipulation of large quantities of Columbia River water (i.e., greater than 450,000 gallons) within AP-106, the associated tanks and the supporting infrastructure (i.e., transfer line piping). This risk becomes more pronounced if there is a process upset and the tank walls remain exposed to a corrosive condition longer than intended. As long as the river water is blended into the supernate in a timely fashion, and the waste is adjusted appropriately with corrosion inhibitors, corrosion may be minimized and the final condition of the supernate in AP-106 and the associated tanks is expected to be in compliance with corrosion chemistry requirements. Contingency plans will be made to minimize the impact of a process upset. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Analysis of thermal and mechanical properties with inventory level of the molten salt storage tank in central receiver concentrating solar power plants

Molten salt thermal energy storage (TES) tanks ensure steady power output of concentrating solar power (CSP) plants; however, recent tank failures have highlighted the need for further analysis. Current studies primarily focus on analyzing the molten salt flow, heat transfer, and thermal efficiency. Additionally, research on the latest tank structures is limited and lacks newest experimental validation. This study measures temperature and molten salt inventory levels in the high-temperature tank at a 50 MW central receiver CSP plant, connected to the power grid in 2019. A multi-physics model was developed to evaluate thermal and mechanical properties of TES tanks by combining computational fluid dynamics and finite element modeling using real plant data. Heat loss, temperature, displacement, and stress distribution of the tank at different inventory levels were investigated. Results show that ambient air velocity near the tank roof reaches 2.14 m/s, much higher than 0.2 m/s near the wall. The temperatures of inventory fluid and tank are close, varying slightly at different levels due to thermal conduction and radiation. Because the heat loss strongly depends on temperature, the total tank loss remains nearly constant across inventory levels. Larger temperature gradients and thermal stresses are primarily localized along the tank floor edge and the air-salt interface. Notably, the maximum thermal stress at the tank edge is three times higher than that at the interface. The magnitude of total stress changes by less than 5 MPa with and without thermal load, indicating that high temperatures exert only a minor impact on tank stress. In contrast, thermal load significantly affects tank deformation, particularly at the roof edge, where values exceed 150 mm. Despite the large variation in molten salt levels, tank wall temperatures and displacements present a minor change, suggesting a weak correlation with inventory levels. In conclusion, the findings obtained in this study provide important insights on the TES tank that could be used to optimize tank design and operation strategies.

14 SOLAR ENERGY↗
DOE OSTI2011

PILOT-SCALE TESTING OF THE SUSPENSION OF MST, CST, AND SIMULATED SLUDGE SLURRIES IN A SLUDGE TANK

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 (i.e., Tank 41H) to house the process. Following strontium, actinide, and cesium removal, the concentrated solids will be transported to a sludge tank (i.e., monosodium titanate (MST)/sludge solids to Tank 42H or Tank 51H and crystalline silicotitanate (CST) to Tank 40H) for eventual transfer to the Defense Waste Processing Facility (DWPF). Savannah River National Laboratory (SRNL) is conducting pilot-scale mixing tests to determine the pump requirements for mixing MST, CST, and simulated sludge. The purpose of this pilot scale testing is to determine the pump requirements for mixing MST and CST with sludge in a sludge tank and to determine whether segregation of particles occurs during settling. Tank 40H and Tank 51H have four Quad Volute pumps; Tank 42H has four standard pumps. The pilot-scale tank is a 1/10.85 linear scaled model of Tank 40H. The tank diameter, tank liquid level, pump nozzle diameter, pump elevation, and cooling coil diameter are all 1/10.85 of their dimensions in Tank 40H. The pump locations correspond to the current locations in Tank 40H (Risers B2, H, B6, and G). The pumps are pilot-scale Quad Volute pumps. Additional settling tests were conducted in a 30 foot tall, 4 inch inner diameter clear column to investigate segregation of MST, CST, and simulated sludge particles during settling.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

DEMONSTRATION OF THE NEXT-GENERATION CAUSTIC-SIDE SOLVENT EXTRACTION SOLVENT WITH 2-CM CENTRIFUGAL CONTRACTORS USING TANK 49H WASTE AND WASTE SIMULANT

Researchers successfully demonstrated the chemistry and process equipment of the Caustic-Side Solvent Extraction (CSSX) flowsheet using MaxCalix for the decontamination of high level waste (HLW). The demonstration was completed using a 12-stage, 2-cm centrifugal contactor apparatus at the Savannah River National Laboratory (SRNL). This represents the first CSSX process demonstration of the MaxCalix solvent system with Savannah River Site (SRS) HLW. Two tests lasting 24 and 27 hours processed non-radioactive simulated Tank 49H waste and actual Tank 49H HLW, respectively. Conclusions from this work include the following. The CSSX process is capable of reducing {sup 137}Cs in high level radioactive waste by a factor of more than 40,000 using five extraction, two scrub, and five strip stages. Tests demonstrated extraction and strip section stage efficiencies of greater than 93% for the Tank 49H waste test and greater than 88% for the simulant waste test. During a test with HLW, researchers processed 39 liters of Tank 49H solution and the waste raffinate had an average decontamination factor (DF) of 6.78E+04, with a maximum of 1.08E+05. A simulant waste solution ({approx}34.5 liters) with an initial Cs concentration of 83.1 mg/L was processed and had an average DF greater than 5.9E+03, with a maximum DF of greater than 6.6E+03. The difference may be attributable to differences in contactor stage efficiencies. Test results showed the solvent can be stripped of cesium and recycled for {approx}25 solvent turnovers without the occurrence of any measurable solvent degradation or negative effects from minor components. Based on the performance of the 12-stage 2-cm apparatus with the Tank 49H HLW, the projected DF for MCU with seven extraction, two scrub, and seven strip stages operating at a nominal efficiency of 90% is {approx}388,000. At 95% stage efficiency, the DF in MCU would be {approx}3.2 million. Carryover of organic solvent in aqueous streams (and aqueous in organic streams) was less than 0.1% when processing Tank 49H HLW. The entrained solvent concentration measured in the decontaminated salt solution (DSS) was as much as {approx}140 mg/L, although that value may be overstated by as much as 50% due to modifier solubility in the DSS. The entrained solvent concentration was measured in the strip effluent (SE) and the results are pending. A steady-state concentration factor (CF) of 15.9 was achieved with Tank 49H HLW. Cesium distribution ratios [D(Cs)] were measured with non-radioactive Tank 49H waste simulant and actual Tank 49H waste. Below is a comparison of D(Cs) values of ESS and 2-cm tests. Batch Extraction-Strip-Scrub (ESS) tests yielded D(Cs) values for extraction of {approx}81-88 for tests with Tank 49H waste and waste simulant. The results from the 2-cm contactor tests were in agreement with values of 58-92 for the Tank 49H HLW test and 54-83 for the simulant waste test. These values are consistent with the reference D(Cs) for extraction of {approx}60. In tests with Tank 49H waste and waste simulant, batch ESS tests measured D(Cs) values for the two scrub stages as {approx}3.5-5.0 for the first scrub stage and {approx}1.0-3.0 for the second scrub stage. In the Tank 49H test, the D(Cs) values for the 2-cm test were far from the ESS values. A D(Cs) value of 161 was measured for the first scrub stage and 10.8 for the second scrub stage. The data suggest that the scrub stage is not operating as effectively as intended. For the simulant test, a D(Cs) value of 1.9 was measured for the first scrub stage; the sample from the second scrub stage was compromised. Measurements of the pH of all stage samples for the Tank 49H test showed that the pH for extraction and scrub stages was 14 and the pH for the strip stages was {approx}7. It is expected that the pH of the second scrub stage would be {approx}12-13. Batch ESS tests measured D(Cs) values for the strip stages to be {approx}0.002-0.010. A high value in Strip No.3 of a test with simulant solution has been attributed to issues associated with the limits of detection for the analytical method. In the 2-cm contactor tests, the first four strip stages of the Tank 49H waste test and all five strip stages in the simulant waste test had higher values than the ESS tests. Only the fifth strip stage D(Cs) value of the Tank 49H waste test matched that of the ESS tests. It is speculated that the less-than-optimal performance of the strip section is caused by inefficiencies in the scrub section. Because strip is sensitive to pH, the elevated pH value in the second scrub stage may be the cause of strip performance. In spite of the D(Cs) values obtained in the scrub and strip sections, testing showed that the solvent system is robust. Average DFs for the process far exceeded targets even though the scrub and strip stages did not function optimally. Correction of the issue in the scrub and strip stages is expected to yield even higher waste DFs.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

TANKS 18 AND 19-F STRUCTURAL FLOWABLE GROUT FILL MATERIAL EVALUATION AND RECOMMENDATIONS

Cementitious grout will be used to close Tanks 18-F and 19-F. The functions of the grout are to: (1) physically stabilize the final landfill by filling the empty volume in the tanks with a non compressible material; (2) provide a barrier for inadvertent intrusion into the tank; (3) reduce contaminant mobility by (a) limiting the hydraulic conductivity of the closed tank and (b) reducing contact between the residual waste and infiltrating water; and (4) providing an alkaline, chemically reducing environment in the closed tank to control speciation and solubility of selected radionuclides. The objective of this work was to identify a single (all-in-one) grout to stabilize and isolate the residual radionuclides in the tank, provide structural stability of the closed tank and serve as an inadvertent intruder barrier. This work was requested by V. A. Chander, High Level Waste (HLW) Tank Engineering, in HLW-TTR-2011-008. The complete task scope is provided in the Task Technical and QA Plan, SRNL-RP-2011-00587 Revision 0. The specific objectives of this task were to: (1) Identify new admixtures and dosages for formulating a zero bleed flowable tank fill material selected by HLW Tank Closure Project personnel based on earlier tank fill studies performed in 2007. The chemical admixtures used for adjusting the flow properties needed to be updated because the original admixture products are no longer available. Also, the sources of cement and fly ash have changed, and Portland cements currently available contain up to 5 wt. % limestone (calcium carbonate). (2) Prepare and evaluate the placement, compressive strength, and thermal properties of the selected formulation with new admixture dosages. (3) Identify opportunities for improving the mix selected by HLW Closure Project personnel and prepare and evaluate two potentially improved zero bleed flowable fill design concepts; one based on the reactor fill grout and the other based on a shrinkage compensating flowable fill mix design. (4) Prepare samples for hydraulic property measurements for comparison to the values in the F and H- Tank Farm Performance Assessments (PAs). (5) Identify a grout mix for the Tanks 18-F and 19-F Grout Procurement Specification [Forty, 2011 a, b, c]. Results for two flowable zero bleed structural fill concepts containing 3/8 inch gravel (70070 Series and LP-8 Series) and a sand only mix (SO Series) are provided in this report. Tank Farm Engineering and SRNL Project Management selected the 70070 mix as the base case for inclusion in Revision 0 of the Tanks 18-F and 19-F grout procurement specification [Forty 2011 a] and requested admixture recommendations and property confirmation for this formulation [Forty, 2011 b]. Lower cementitious paste mixes were formulated because the 70070 mix is over designed with respect to strength and generates more heat from hydration reactions than is desirable for mass pour application. Work was also initiated on a modification of the recommended mix which included shrinkage compensation to mitigate fast pathways caused by shrinkage cracking and poor physical bonding to the tank and ancillary equipment. Testing of this option was postponed to FY12.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

ANALYSIS OF THE LEACHING EFFICIENCY OF INHIBITED WATER AND TANK SIMULANT IN REMOVING RESIDUES ON THERMOWELL PIPES

A key component for the accelerated implementation and operation of the Salt Waste Processing Facility (SWPF) is the recovery of Tank 48H. Tank 48H is a type IIIA tank with a maximum capacity of 1.3 million gallons. Video inspection of the tank showed that a film of solid material adhered to the tank internal walls and structures between 69 inch and 150 inch levels. From the video inspection, the solid film thickness was estimated to be 1mm, which corresponds to {approx}33 kg of TPB salts (as 20 wt% insoluble solids) (1). This film material is expected to be easily removed by single-rinse, slurry pump operation during Tank 48H TPB disposition via aggregation processing. A similar success was achieved for Tank 49H TPB dispositioning, with slurry pumps operating almost continuously for approximately 6 months, after which time the tank was inspected and the film was found to be removed. The major components of the Tank 49H film were soluble solids - Na{sub 3}H(CO{sub 3}){sub 2} (Hydrated Sodium Carbonate, aka: Trona), Al(OH){sub 3} (Aluminum Hydroxide, aka: Gibbsite), NaTPB (Sodium Tetraphenylborate), NaNO{sub 3} (Sodium Nitrate) and NaNO{sub 2} (Sodium Nitrite) (2). Although the Tank 48H film is expected to be primarily soluble solids, it may not behave the same as the Tank 49H film. There is a risk that material on the internal surfaces of Tank 48H could not be easily removed. As a risk mitigation activity, the chemical composition and leachability of the Tank 48H film are being evaluated prior to initiating tank aggregation. This task investigated the dissolution characteristics of Tank 48H solid film deposits in inhibited water and DWPF recycle. To this end, SRNL received four separate 23-inch long thermowell-conductivity pipe samples which were removed from the tank 48H D2 risers in order to determine: (1) the thickness of the solid film deposit, (2) the chemical composition of the film deposits, and (3) the leaching behavior of the solid film deposit in inhibited water (IW) and in DWPF recycle simulant (3).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Impacts of Crust Properties on the Waste Feed Delivery of Hanford Tanks with Flammability Concerns - 18161

Mitigation of flammability concerns within Hanford waste tanks is essential to Safe Storage and Waste Feed Delivery sub-functions of the River Protection Project Mission. The tanks that have a higher propensity for the generation, retention, and release of flammable gas are considered Waste Group A tanks. Group A tanks include 241-SY-103, 241-AN-103, 241-AN-104, 241-AN-105, and 241-AW-101. Successful mitigation of flammability concerns in these tanks is necessary, as they are critical to the completion of the River Protection Project Mission as indicated in the Integrated Waste Feed Delivery Plan. The benchmark for examination of tank flammability issues is 241-SY-101. Studies of Tank 241-SY-101 gas release events showed that the mechanism of gas retention and release was highly dependent on the volume and configuration of a floating crust layer. Beginning in 1993, 241-SY-101 underwent water additions and mixer pump operations resulting in dissolution of the crust. These efforts mitigated the flammability concerns of the tank. A similar mitigation approach was recommended for Tank 241-SY103 and is recommended for the other Waste Group A tanks. However, this recommended mitigation will be more or less effective based on the expected thickness of the crust present in each of the Group A tanks. Considerations of flammable gas generation and release mechanisms were essential in the development of a successful mitigation strategy for Tank 241-SY-101, and will be essential in the development of future mitigation strategies. Because crust properties are difficult to measure, tank surface level trends and current temperature profiles are evaluated to understand crust properties. 241-AN-103 and 241-AW-101 are the only two tanks with a net increase in surface level, indicating a higher generation and retention of flammable gas. Additionally, these are the two tanks with the thickest crusts, which causes both a higher retention of gas and a reduced evaporation rate. Given the current temperature profile, crust thickness for 241-AW-101 was re-evaluated to be 145 cm (57 in) ± 30 cm (12 in) which is different from its historic value. This gives 241-AW-101 the thickest crust, second only to 241-SY-101 prior to mitigation. The crust thickness for 241-AN-103, however, retains its historic value of 89 cm (35 in) ± 16 cm (6 in). These crust properties suggest modifications to the mitigation strategy are needed for each tank. For example, 241-AN-103 and 241-AW-101 will require additional water to dissolve the crust layer before flammability concerns are mitigated and further operations could commence. Implementation of the modified mitigation strategies will mitigate flammability issues and help fulfill the Safe Storage and Waste Feed Delivery sub-functions of the River Protection Project Mission safely and efficiently. (authors)

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DOE OSTI2020

History of Ultrasonic Inspection of High-Level Waste Tanks at SRS - 20220

The Liquid Waste Disposition Projects (LWDP) Structural Authority and Inspection Engineering Support Group has teamed with the Materials Science and Technology Non-destructive Evaluation Group of Savannah River National Laboratory (SRNL) to implement a comprehensive In-Service Inspection (ISI) program for the High-Level Waste (HLW) tanks in the sites tank farms. The purpose of this program is to demonstrate the structural and leak integrity of the tanks to maintain the function of waste containment throughout the desired service life. Four types of waste tanks were constructed at Savannah River Site (SRS) from 1951 thru 1981 to store radioactive nuclear waste from the separations process. The Type I, II and III are carbon steel cylindrical tanks with varying degrees of access to the side walls and very limited access to the tank bottom. The tanks contain 750,000 to 1.3 million gallons of waste and are buried or backfilled with soil. The tanks are 75'-85' in diameter and 24'-33' from tank bottom to the tank roof. Inspection of the HLW tanks is made difficult by radiation, contamination, and small access openings. Through the years these challenges have been overcome by progressive improvements to programs and equipment resulting in the sophisticated wall crawler Ultrasonic Testing (UT) technology of today. A formal inspection program was developed and put in service in 1972. UT thickness measurements were first made in 1967 and 1969 of selected waste tanks using an analog-type instrument to measure the thickness of the carbon steel walls. Routine inspections for thinning were performed from 1972-1985 and then discontinued because no thinning had been observed and this technique could not detect pitting or cracking. UT inspections resumed in 1994 using a sophisticated robotic wall crawler with UT technology capable of detecting thinning, cracking and pitting. The current program focuses on the newer Type III tanks that are used primarily for storage. The program was upgraded in 2003 to include selected regions of the tank wall, secondary wall and annulus floor on a 7 to 10-year frequency. The facility is currently in its third cycle of tank inspections. Thus far, there have been no reportable indications of service induced degradation. This result provides assurance that the chemistry control program has been effective at mitigating corrosion and that the tanks remain structurally sound even after more than 40 years of service. This paper will present the UT technology first used at SRS and the evolution to the current systems and their capabilities. Additionally, plans for equipment upgrades that will improve the extent of inspection will be discussed. (authors)

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NASA NTRS2015

Differential Draining of Parallel-Fed Propellant Tanks in Morpheus and Apollo Flight

Parallel-fed propellant tanks are an advantageous configuration for many spacecraft. Parallel-fed tanks allow the center of gravity (cg) to be maintained over the engine(s), as opposed to serial-fed propellant tanks which result in a cg shift as propellants are drained from tank one tank first opposite another. Parallel-fed tanks also allow for tank isolation if that is needed. Parallel tanks and feed systems have been used in several past vehicles including the Apollo Lunar Module. The design of the feedsystem connecting the parallel tank is critical to maintain balance in the propellant tanks. The design must account for and minimize the effect of manufacturing variations that could cause delta-p or mass flowrate differences, which would lead to propellant imbalance. Other sources of differential draining will be discussed. Fortunately, physics provides some self-correcting behaviors that tend to equalize any initial imbalance. The question concerning whether or not active control of propellant in each tank is required or can be avoided or not is also important to answer. In order to provide data on parallel-fed tanks and differential draining in flight for cryogenic propellants (as well as any other fluid), a vertical test bed (flying lander) for terrestrial use was employed. The Morpheus vertical test bed is a parallel-fed propellant tank system that uses passive design to keep the propellant tanks balanced. The system is operated in blow down. The Morpheus vehicle was instrumented with a capacitance level sensor in each propellant tank in order to measure the draining of propellants in over 34 tethered and 12 free flights. Morpheus did experience an approximately 20 lb/m imbalance in one pair of tanks. The cause of this imbalance will be discussed. This paper discusses the analysis, design, flight simulation vehicle dynamic modeling, and flight test of the Morpheus parallel-fed propellant. The Apollo LEM data is also examined in this summary report of the flight data.

Hurlbert, Eric↗
DOE OSTI2011

ASSESSMENT OF THE ABILITY OF STANDARD SLURRY PUMPS TO MIX SOLIDS WITH LIQUIDS IN TANK 50H

Tank 50H is the feed tank for the Saltstone Production Facility (SPF). In the summer of 2011, Tank 50H contained two standard slurry pumps and two quad volute slurry pumps. Current requirements for mixing operation is to run three pumps for one hour prior to initiating a feed transfer to SPF. Savannah River Site (SRS) Liquid Waste moved both of the Quad Volute pumps from Tank 50H to Tank 51H to replace pumps in Tank 51H that were failing. In addition, one of the standard pumps in Tank 50H exhibits high seal leakage and vibration. SRS Liquid Waste requested Savannah River National Laboratory (SRNL) to conduct a study to evaluate the feasibility of mixing the contents of Tank 50H with one to three standard slurry pumps. To determine the pump requirements to mix solids with liquids in Tank 50H, the author reviewed the pilot-scale blending work performed for the Small Column Ion Exchange Process (SCIX), SRNL computational fluid dynamics (CFD) modeling, Tank 50H operating experience, and the technical literature, and applied the results to Tank 50H to determine the number, size, and operating parameters of pumps needed to mix the solid particles with the liquid in Tank 50H. The analysis determined pump requirements to suspend the solids with no 'dead zones', but did not determine the pump requirements to produce a homogeneous suspension. In addition, the analysis determined the pump requirements to prevent the accumulation of a large amount of solid particles under the telescoping transfer pump. The conclusions from this analysis follow: (1) The analysis shows that three Quad Volute pumps should be able to suspend the solid particles expected ({approx}0.6 g/L insoluble solids, {approx}5 micron) in Tank 50H. (2) Three standard slurry pumps may not be able to suspend the solid particles in Tank 50H; (3) The ability of two Quad Volute pumps to fully suspend all of the solid particles in Tank 50H is marginal; and (4) One standard slurry pump should be able to achieve a cleaning radius larger than 43.5 feet, which will prevent large amounts of solid particles from settling under the telescoping transfer pump (TTP). The report recommends a pump operating approach to maximize the achieved cleaning radius.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2012

Form and Aging of Plutonium in Savannah River Site Waste Tank 18

Process modeling; injection molding; long-fiber thermoplastic; fiber orientation; fiber lengt This report provides a summary of the effects of aging on and the expected forms of plutonium in Tank 18 waste residues. The findings are based on available information on the operational history of Tank 18, reported analytical results for samples taken from Tank 18, and the available scientific literature for plutonium under alkaline conditions. These findings should apply in general to residues in other waste tanks. However, the operational history of other waste tanks should be evaluated for specific conditions and unique operations (e.g., acid cleaning with oxalic acid) that could alter the form of plutonium in heel residues. Based on the operational history of other tanks, characterization of samples from the heel residues in those tanks would be appropriate to confirm the form of plutonium. During the operational period and continuing with the residual heel removal periods, Pu(IV) is the dominant oxidation state of the plutonium. Small fractions of Pu(V) and Pu(VI) could be present as the result of the presence of water and the result of reactions with oxygen in air and products from the radiolysis of water. However, the presence of Pu(V) would be transitory as it is not stable at the dilute alkaline conditions that currently exists in Tank 18. Most of the plutonium that enters Savannah River Site (SRS) high-level waste (HLW) tanks is freshly precipitated as amorphous plutonium hydroxide, Pu(OH) 4(am) or hydrous plutonium oxide, PuO 2(am,hyd) and coprecipitated within a mixture of hydrous metal oxide phases containing metals such as iron, aluminum, manganese and uranium. The coprecipitated plutonium would include Pu 4+ that has been substituted for other metal ions in crystal lattice sites, Pu 4+ occluded within hydrous metal oxide particles and Pu 4+ adsorbed onto the surface of hydrous metal oxide particles. The adsorbed plutonium could include both inner sphere coordination and outer sphere coordination of the plutonium. PuO 2(am,hyd) is also likely to be present in deposits and scales that have formed on the steel surfaces of the tank. Over the operational period and after closure of Tank 18, Ostwald ripening has and will continue to transform PuO 2(am,hyd) to a more crystalline form of plutonium dioxide, PuO 2(c) . After bulk waste removal and heel retrieval operations, the free hydroxide concentration decreased and the carbonate concentration in the free liquid and solids increased. Consequently, a portion of the PuO 2(am,hyd) has likely been converted to a hydroxy-carbonate complex such as Pu(OH) 2 (CO 3 ) (s) . or PuO(CO 3 ) · xH 2 O (am) . Like PuO 2(am,hyd) , Ostwald ripening of Pu(OH) 2 (CO 3 ) (s) or PuO(CO 3 ) · xH 2 O (am) would be expected to occur to produce a more crystalline form of the plutonium carbonate complex. Due to the high alkalinity and low carbonate concentration in the grout formulation, it is expected that upon interaction with the grout, the plutonium carbonate complexes will transform back into plutonium hydroxide. Although crystalline plutonium dioxide is the more stable thermodynamic state of Pu(IV), the low temperature and high water content of the waste during the operating and heel removal periods in Tank 18 have limited the transformation of the plutonium into crystalline plutonium dioxide. During the tank closure period of thousands of years, transformation of the plutonium into a more crystalline plutonium dioxide form would be expected. However, the continuing presence of water, reaction with water radiolysis products, and low temperatures will limit the transformation, and will likely maintain an amorphous Pu(OH) 4 or PuO 2(am,hyd) form on the surface of any crystalline plutonium dioxide produced after tank closure. X-ray Absorption Spectroscopic (XAS) measurements of Tank 18 residues are recommended to confirm coordination environments of the plutonium. If the presence of PuO(CO 3 ) (am,hyd) is confirmed by XAS, it is recommended that experiments be conducted to determine if plutonium carbonates are transformed back into PuO 2(am,hyd) upon contact with grout.

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