Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Tanks”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Waste Retrieval and Inspection Operations in Hanford Tank 241-AY-102 - 18234

In August 2012, a periodic annulus inspection of tank 241-AY-102 (AY-102) identified a leak from the primary tank into the secondary containment. A pumping plan was developed in 2013 to provide a path forward for recommended remediation actions to be implemented as part of the AY-102 Recovery Project. On March 21, 2014, the Washington State Department of Ecology issued an Administrative Order requiring Washington River Protection Solutions and the United States Department of Energy to conduct actions related to and including the removal of waste from AY-102. The parties agreed to resolve the appeal of the Administrative Order through a Settlement Agreement which addressed the remaining requirements and implemented enforceable milestone dates, including completion of waste removal operations, and performance of an inspection aimed at determining the cause of the leak. The AY-102 Recovery Project was developed to address the Settlement Agreement requirements. While retrieval of waste from Single-Shell Tanks has been performed at Hanford for decades, retrieval from Double-Shell Tank AY-102 required adaptation of the existing technologies to a new environment on a larger scale than previously encountered. Despite countless challenges and obstacles encountered throughout, the project successfully completed system design, fabrication, installation, testing, and retrieval operations within a highly compressed, aggressive schedule. Waste removal activities in AY-102 completed in February 2017. Subsequent inspection activities were completed as part of a multi-step process aimed at determining the likely cause of failure and assessing the feasibility of repair. A variety of input data were used in evaluating the likely failure mechanism, such as video examinations that revealed numerous through-floor penetrations and significant degradation across the visible surface area. Based on the operational history of the tank, corrosion testing and analysis, and the visual appearance of the confirmed leak sites, service-induced pitting corrosion due to the historic waste composition and operating conditions appears to be the primary degradation mechanism leading to failure of the tank. The inspection data has demonstrated that repairing and returning AY-102 to service would likely introduce substantial technical, logistical, and financial challenges due to the extent of bottom-plate damage. As a result, tank AY-102 will ultimately be closed. (authors)

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

A Prototype Dual Robot System to Perform Ultrasonic and Visual Inspection for the Bottom of Double-Shell Tanks - 18624

Up to this point, ultrasonic inspection-based condition data has only been available for double-shell tank (DST) sidewalls because direct inspection access to the primary tank bottom is limited to vent duct channels in an insulating refractory pad that the primary tank rests on. Probe access through the air slot would provide the opportunity to get information about the condition of the bottom of the primary tank, but it is a challenge to deploy a crawling robot that is capable of performing nondestructive ultrasonic and visual inspection through confined air slots. As such, a conceptual prototype of a deployable inspection robot system to enable ultrasonic and visual inspection for DST base through ventilation ducts was designed and fabricated. This prototype dual robot system consisting of the AnnulusBot and the MouseBot can be integrated with nondestructive evaluation (NDE) sensors to inspect and examine the physical properties of the underside of DSTs to enable status assessment. The AnnulusBot was designed to carry the MouseBot and to be deployed to the annulus space through a riser. To deploy the MouseBot to every ventilation channel in the annulus, the arm consisting of a boom and a forearm was used to place the MouseBot on the underside of the tank. The AnnulusBot used segmented wheels enable to traverse pipes and other potential obstacles. The cable management system utilized motorized wheels to feed the cable into the ventilation channel. This would reduce the amount of work that the MouseBot would have to do during inspection. This feeding mechanism would also be used to retrieve the MouseBot at the end of its inspection. Additionally, if the MouseBot fails, this mechanism would be used for retrieval. Once deployed, the MouseBot navigates to the center of the tank via the air ventilation channel beneath the inner shell (the primary tank) while inspecting the space. The MouseBot is then retrieved from the channel by a combination of its own drive power and the AnnulusBot retracting the attached umbilical cord. Compare with the AnnulusBot, the physical dimensional limitations of the MouseBot were a greater challenge. As the surface state of the concrete of the air channels could have variable texture, and may contain debris, it was decided not to travel along this surface. The ceiling of these channels is carbon steel and can be utilized throughout the channel. To use this travel surface, magnetic wheels were employed. A foreseeable problem with the use of magnets on this surface, is that they would preclude the use of eddy currents sensors. However, other technologies like ultrasonic technology sensors should be unaffected. Laboratory scale test was performed on a mock-up single wedge of the refractory pad to evaluate maneuverability of the MouseBot. The electronic components for the prototype would work in the ranges of 150-185 deg. F (65.6-85 deg. C). Both the AnnulusBot and MouseBot will be subject to constant radiation. All major printed circuit board (PCB) microcontroller components were designed to be situated outside of the annulus space and inside the main control panel to avoid radiation-induced failure. As future work, electronic components including the Arduinos that used Atmel commercial microcontrollers will be replaced with the high temperature rated Atmel microcontrollers so that the robots can be operated reliably at ambient temperatures up to 200 deg. F (93.3 deg. C). In addition, the robots will be service life tested to evaluate performance at elevated temperature and under gamma irradiation. (authors)

42 ENGINEERING↗
DOE OSTI2019

Finite Element Structural Analysis Evaluating New Retrieval Strategies in the Hanford Waste Tanks 1 - 19125

Several waste retrieval methods being considered for the Hanford underground single- and double-shell nuclear waste storage tanks would require changes to the equipment loads above the tanks or structural modifications to the tanks themselves. Detailed structural analysis has been used in the planning phase to ensure that the reinforced concrete tanks continue to meet structural design codes in the modified configuration of these waste retrieval options. The feasibility of installing new single and multiple large risers penetrating the tank dome was evaluated using this approach. This paper summarizes the structural analysis methods and design codes used to evaluate the introduction of new unreinforced penetrations in a single-shell tank dome. The anticipated equipment loads during current and future waste retrieval operations are evaluated to ensure the continued structural integrity of the tank under thermal, dead weight, and seismic loads. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Developing and Implementing New Waste Chemistry Controls for Hanford's Double-Shell Tanks - 20041

Waste chemistry controls for the Hanford double-shell tanks (DSTs) were established in the 1980's in response to tank failures caused by stress corrosion cracking (SCC) at the Savannah River Site (SRS). The controls were established based on a combination of SRS chemistry limits and corrosion testing results. Conditions in the Hanford DSTs have changed over time, with the temperature in the majority of the DSTs dropping below 50 deg. C. Testing indicated that the original chemistry control specification and SCC testing performed in 2010 did not protect against pitting corrosion mechanisms - what is believed to have caused the failure of tank 241-AY-102. New waste chemistry controls are necessary to protect the DSTs from both SCC and pitting corrosion. Savannah River National Laboratory (SRNL), with input from the Tank Integrity Expert Panel (TIEP) Corrosion Subgroup (CSG), performed a statistically based investigation of nitrate and halide ion induced pitting corrosion. The investigation was intended to develop a comprehensive waste chemistry envelope that minimizes the risk of both SCC and pitting caused by halide and nitrate ions. The waste chemistry envelope needed to be robust enough to address future waste retrieval and process changes which could significantly change the waste composition of the DSTs. The experimental design allowed the statistically significant ions and their effect on pitting corrosion to be determined. SRNL developed the 'pitting factor' which is an empirical relationship between the statistically significant inhibitive species (hydroxide, and nitrite), and pitting inducing species (nitrate, chloride, and fluoride). The coefficients are weighted factors that show the degree of influence the species have on the propensity for pitting. New waste chemistry control limits were recommended by SRNL, and concurred with by the TIEP CSG, that incorporated the pitting factor along with other limits. The controls developed to reduce the risk of pitting corrosion were evaluated to determine if they also protected against SCC. Hundreds of test results were reviewed and compared against the proposed limits. With the exception of one test result, instances where cracking was observed corresponded to chemistry that was outside of the proposed limits - indicating that the chemistry controls developed for pitting also adequately addressed SCC concerns. Existing tank composition estimates were evaluated against the new chemistry controls - three current tank chemistries are suspect, and may not meet the new chemistry control requirements. These included the interstitial liquid (liquid associated with solids) of DSTs 241-AN-102, 241-AN-106, 241-AN-107, and 241-AY-101. Measures are ongoing to evaluate the tanks with the suspect chemistry. These include varying combinations of: performing additional evaluations (history of use, modeling); DST specific laboratory testing; and, pursuing core samples of the DSTs. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Solubility Predictions for Hanford Tank Concentrates with HSC - 20459

The commercially available Outotec HSC 9.9.0{sup R} provides excellent predictions for the solubilities of many species for Hanford waste tank concentrates. The HSC solubility predictions with a Harvie activity model agreed well with five boildowns that showed solubility limits for NaNO{sub 3}, NaNO{sub 2}, Na{sub 2}CO{sub 3}, NaF, Na{sub 2}SO{sub 4}, and Na{sub 3}PO{sub 4}. However, the HSC did not predict density and therefore water content very well and therefore we used the measured densities and derived water content from the difference between measured density and assays. Furthermore, we adjusted the HSC enthalpy for the minor species Na{sub 3}PO{sub 4}*NaF double salt in order to fit the five boildowns as well. Previous work has shown that gibbsite becomes and remains supersaturated in all of these boildowns and so there was no alumina precipitation despite supersaturation. Furthermore, an equilibrium model like HSC always shows complete oxidation of any TOC in the presence of nitrate and nitrite. We therefore suppressed the HSC oxidation of acetate and oxalate in order to fit measured acetate and oxalate solubilities as TOC. Space in Hanford waste tanks is very limited and therefore evaporator campaigns continue to recover needed tank space from dilute tank liquids. Prior to each evaporator campaign, a boildown of a sample of tank liquid for each campaign provides a basis for planning by measuring density, water activity, soluble species, and solids precipitation as a function of concentration at 18 deg. C. These boildowns then provide validations and calibrations for the HSC solubility prediction for Hanford wastes. Previous work has shown the solubilities of minor electrolytes in these five boildowns follow rather simple power law solubility products. Hanford's 222-S laboratory has reported each of five boildowns for concentrated liquids from five waste tanks and tank blends. All boildowns eventually showed the precipitation of the dominant electrolyte, NaNO{sub 3}, and overall solution activity largely drives all solubility. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Methane Emissions Produced by Pneumatic Devices and Produced Water Tanks on Natural Gas Wellsites

In recent years, more scrutiny has been placed on the release of greenhouse gasses (GHGs) by the oil and gas industry in North America as climate concerns increase. In the coming years, stricter regulations proposed by the Environmental Protection Agency (EPA) concerning the release of GHGs will further direct attention to GHG emissions quantification, modeling, and overall reduction. Active natural gas wellsites employ production equipment that routinely emits methane during normal operation. Production equipment often includes, but is not limited to, gas production units (GPUs), pneumatic controllers (PCs) and actuators powered by produced natural gas, and produced water storage tanks. This work details direct methane emission measurements taken at active natural gas wellsites originating from intermittent pneumatic controllers and produced water storage tanks. Efforts to model methane flows originating from these sources are also detailed, and those results are compared to direct measurement. The direct methane emissions measurement campaign collected flow data from two active dry wellsites in the Marcellus shale region. These measurement campaigns captured, in total, several weeks of continuous data from these sites. Data included multiple pneumatic device vent flowrate channels, a single channel monitoring total emissions vented from the produced water storage tanks, and corresponding site weather data. Periodic composition measurements were taken from flows vented from produced water tanks. Computational modeling efforts attempted to mimic a given site’s methane emissions behavior given limited input parameters. Direct measurement data and simulation data yielded, through reduction and analysis, apparent methane emissions factors, statistics on pneumatic device actuation events, important relationships between GPU parameters and pneumatic device actuation events, produced water storage tank vent flows and flow compositions, and parameters most contributing to the magnitude and frequency of these fugitive methane emissions. Measurements, considering data from a 72hr period, produced PC emissions factors from 0.008 to 0.03 SCFH per device with an average device emitting 0.026 SCFH at the first site. The second site produced PC emissions factors spanning from 0.05 to 25.47 SCFH with an average device emitting 1.93 SCFH not including the 25.47 SCFH device, which was assumed to be malfunctioning. Two unique water tank emission measurements were made, 618 g CH4 per hour and 32.6 g CH4 per hour. On a water basis, the water tank emissions factors were 0.66 and 0.042 kg CH4 per bbl of water, respectively.

03 NATURAL GAS↗
DOE OSTI2016

Characterization of the SRNL-Washed tank 51 sludge batch 9 qualification sample

Savannah River National Laboratory (SRNL) personnel have been requested to qualify the next sludge batch (Sludge Batch 9 – SB9) for processing at the Defense Waste Processing Facility (DWPF). To accomplish this task, Savannah River Remediation (SRR) sent SRNL a 3-L sample of Tank 51H slurry to be characterized, washed, and then used in a lab-scale demonstration of the DWPF flowsheet (after combining with Tank 40H sludge). SRNL has washed the Tank 51H sample per the Tank Farm washing strategy as of October 20, 2015. A part of the qualification process is extensive radionuclide and chemical characterization of the SRNL-washed Tank 51H slurry. This report documents the chemical characterization of the washed slurry; radiological characterization is in progress and will be documented in a separate report. The analytical results of this characterization are comparable to the Tank Farm projections. Therefore, it is recommended that SRNL use this washed slurry for the ongoing SB9 qualification activities.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Empirical characterization of vertical-tube inlets in hot-water storage tanks

Hot-water storage in residential and commercial tanks is of growing interest for peak-shifting the electrical demand associated with hot-water loads. How the water enters the tank can significantly affect the extraction efficiency of the storage. Vertical-tube inlets (VTIs) direct cold water into the tank. The VTI design influences whether large-scale mixing occurs, which can reduce the delivery capacity of the hot-water storage. In this work, the mixing at the VTI discharge was characterized by the eddy diffusivity factor (EDF) in an allometric curve fit to the ratio Re:Ri using inlet superficial velocities. The full experimental campaign tested VTI's with Re’s between 170 and 22,300 and Ri's between 0 and 376. Animated visualization of the experimentally measured data is provided, showing tank temperature evolution during inlet flows. The most predictive correlations for EDF are for VTI Re in the transition zone (i.e. ~2300 < Re < ~10,000) and at a Ri corresponding to a stably stratified tank (i.e. Ri > 5). For vertical-tubes that distribute cold water below the thermocline, increasing the EDF will decrease the stratification in a hot-water tank as EDF quantifies inlet mixing. Overall, the new correlations for VTIs can be used to design and model thermally-stratified storage tanks.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Force-controlled absorption in a fully-nonlinear numerical wave tank

An active control methodology for the absorption of water waves in a numerical wave tank is introduced. This methodology is based upon a force-feedback technique which has previously been shown to be very effective in physical wave tanks. Unlike other methods, an a-priori knowledge of the wave conditions in the tank is not required; the absorption controller being designed to automatically respond to a wide range of wave conditions. In comparison to numerical sponge layers, effective wave absorption is achieved on the boundary, thereby minimising the spatial extent of the numerical wave tank. In contrast to the imposition of radiation conditions, the scheme is inherently capable of absorbing irregular waves. Most importantly, simultaneous generation and absorption can be achieved. This is an important advance when considering inclusion of reflective bodies within the numerical wave tank. In designing the absorption controller, an infinite impulse response filter is adopted, thereby eliminating the problem of non-causality in the controller optimisation. Two alternative controllers are considered, both implemented in a fully-nonlinear wave tank based on a multiple-flux boundary element scheme. To simplify the problem under consideration, the present analysis is limited to water waves propagating in a two-dimensional domain. The paper presents an extensive numerical validation which demonstrates the success of the method for a wide range of wave conditions including regular, focused and random waves. The numerical investigation also highlights some of the limitations of the method, particularly in simultaneously generating and absorbing large amplitude or highly-nonlinear waves. The findings of the present numerical study are directly applicable to related fields where optimum absorption is sought; these include physical wavemaking, wave power absorption and a wide range of numerical wave tank schemes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Status of the Development of In-Tank/At-Tank Separations Technologies for High-Level Waste Processing for the U.S. Department of Energy

Within the U.S. Department of Energy’s (DOE) Office of Technology Innovation and Development, the Office of Waste Processing manages a research and development program related to the treatment and disposition of radioactive waste. At the Savannah River (South Carolina) and Hanford (Washington) Sites, approximately 90 million gallons of waste are distributed among 226 storage tanks (grouped or collocated in “tank farms”). This waste may be considered to contain mixed and stratified high activity and low activity constituent waste liquids, salts and sludges that are collectively managed as high level waste (HLW). A large majority of these wastes and associated facilities are unique to the DOE, meaning many of the programs to treat these materials are “first-of-a-kind” and unprecedented in scope and complexity. As a result, the technologies required to disposition these wastes must be developed from basic principles, or require significant re-engineering to adapt to DOE’s specific applications. Of particular interest recently, the development of In-tank or At-Tank separation processes have the potential to treat waste with high returns on financial investment. The primary objective associated with In-Tank or At-Tank separation processes is to accelerate waste processing. Insertion of the technologies will (1) maximize available tank space to efficiently support permanent waste disposition including vitrification; (2) treat problematic waste prior to transfer to the primary processing facilities at either site (i.e., Hanford’s Waste Treatment and Immobilization Plant (WTP) or Savannah River’s Salt Waste Processing Facility (SWPF)); and (3) create a parallel treatment process to shorten the overall treatment duration.

High level waste↗
DOE OSTI2014

Exploring Engineering Control through Process Manipulation of Radioactive Liquid Waste Tank Chemical Cleaning

One method of remediating legacy liquid radioactive waste produced during the cold war, is aggressive in-tank chemical cleaning. Chemical cleaning has successfully reduced the curie content of residual waste heels in large underground storage tanks; however this process generates significant chemical hazards. Mercury is often the bounding hazard due to its extensive use in the separations process that produced the waste. This paper explores how variations in controllable process factors, tank level and temperature, may be manipulated to reduce the hazard potential related to mercury vapor generation. When compared using a multivariate regression analysis, findings indicated that there was a significant relationship between both tank level (p value of 1.65x10 -23 ) and temperature (p value of 6.39x10 -6 ) to the mercury vapor concentration in the tank ventilation system. Tank temperature showed the most promise as a controllable parameter for future tank cleaning endeavors. Despite statistically significant relationships, there may not be confidence in the ability to control accident scenarios to below mercury’s IDLH or PAC-III levels for future cleaning initiatives.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Low-Cost Efficient Manufacturing of Pressurized Conformable Compressed Natural Gas Storage Tanks

The project goal was to combine welding and superplastic forming (SPF) processes to develop a conformal pressure vessel with >90% conformability, >12 MJ/kg energy density, and <$\$$1500 tank cost. PNNL investigated an extensive set of geometries and materials showing that reinforcement geometries based on the Schwarz-P minimal surface spanning a volume produced the highest flexibility in tank geometry, conformability, and nearly met the energy density target (11.9 vs. 12 MJ/kg) based on Titanium 6Al-4V material strength. The idealized geometry proved very challenging to achieve using welding and SPF of either tubing or sheet metal. PNNL demonstrated that full Schwarz-P shapes could be formed from titanium tubing using hot metal gas forming. However, that approach was discontinued because of the many components which required joining to assemble a tank structure. Superplastic blow-forming of a welded, multi-sheet pack was further developed using PNNL’s E-beam welding and SPF capabilities. Several sheet-pack designs were welded and formed, culminating in a small demonstration tank designed to withstand the design burst pressure. X-rays confirmed that the modeled internal structure was achieved during forming. During pressure tested the tank leaked (short of the required burst pressure) at thin spots in irregular E-beam welds connecting the outer pressure boundary to the inner reinforcing layers. However, the tank did not burst and the flat sides of the conformal tank were maintained, confirming the integrity of the internal reinforcements. Further refinement of the weld energy and speed plus the control of an automated welding machine would improve weld quality and increase the pressure to leak or burst.

03 NATURAL GAS↗
DOE OSTI2015

Sample Results From Tank 48H Samples HTF-48-14-158, -159, -169, and -170

Savannah River National Laboratory (SRNL) analyzed samples from Tank 48H in support of determining the cause for the unusually high dose rates at the sampling points for this tank. A set of two samples was taken from the quiescent tank, and two additional samples were taken after the contents of the tank were mixed. The results of the analyses of all the samples show that the contents of the tank have changed very little since the analysis of the previous sample in 2012. The solids are almost exclusively composed of tetraphenylborate (TPB) salts, and there is no indication of acceleration in the TPB decomposition. The filtrate composition shows a moderate increase in salt concentration and density, which is attributable to the addition of NaOH for the purposes of corrosion control. An older modeling simulation of the TPB degradation was updated, and the supernate results from a 2012 sample were run in the model. This result was compared to the results from the 2014 recent sample results reported in this document. The model indicates there is no change in the TPB degradation from 2012 to 2014. SRNL measured the buoyancy of the TPB solids in Tank 48H simulant solutions. It was determined that a solution of density 1.279 g/mL (~6.5M sodium) was capable of indefinitely suspending the TPB solids evenly throughout the solution. A solution of density 1.296 g/mL (~7M sodium) caused a significant fraction of the solids to float on the solution surface. As the experiments could not include the effect of additional buoyancy elements such as benzene or hydrogen generation, the buoyancy measurements provide an upper bound estimate of the density in Tank 48H required to float the solids.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Results for the first quarter calendar year 2017 tank 50H salt solution sample

In this memorandum, the chemical and radionuclide contaminant results from the First Quarter Calendar Year 2017 (CY17) sample of Tank 50H salt solution are presented in tabulated form. The First Quarter CY17 Tank 50H samples [a 200 mL sample obtained 6” below the surface (HTF-50-17-7) and a 1 L sample obtained 66” from the tank bottom (HTF-50-17-8)] were obtained on January 15, 2017 and received at Savannah River National Laboratory (SRNL) on January 16, 2017. Prior to obtaining the samples from Tank 50H, a single pump was run at least 4.4 hours and the samples were pulled immediately after pump shut down. All volatile organic analysis (VOA) and semi-volatile organic analysis (SVOA) were performed on the surface sample and all other analyses were performed on the variable depth sample. The information from this characterization will be used by Savannah River Remediation (SRR) for the transfer of aqueous waste from Tank 50H to the Saltstone Production Facility, where the waste will be treated and disposed of in the Saltstone Disposal Facility. This memorandum compares results, where applicable, to Saltstone Waste Acceptance Criteria (WAC) limits and targets. The chemical and radionuclide contaminant results from the characterization of the First Quarter CY17 sampling of Tank 50H were requested by SRR personnel and details of the testing are presented in the SRNL Task Technical and Quality Assurance Plan (TTQAP). This memorandum is part of Deliverable 2 from SRR request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals will be documented at a later time per the TTQAP for the Tank 50H saltstone task.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Spectroscopic Properties of Tc(I) Tricarbonyl Species Relevant to the Hanford Tank Waste

Technetium-99 (Tc) exists predominately in soluble forms in the liquid supernatant and salt cake fractions of the nuclear tank waste stored at the U.S. DOE Hanford Site. In the strongly alkaline environments prevalent in the tank waste, its dominant chemical form is pertechnetate (TcO4-, oxidation state +7). However, attempts to remove Tc from the Hanford tank waste using ion-exchange processes specific to TcO 4 - only met with limited success, particularly processing tank waste samples containing elevated concentrations of organic complexants. This suggests that a significant fraction of the soluble Tc can be present as non-pertechnetate low-valent Tc (oxidation state < +7) (non-pertechnetate). The chemical identities of these non-pertechnetate species are poorly understood. Previous analysis of the SY-101 and SY-103 tank waste samples provided strong evidence that non-pertechnetate can be comprised of [Tc(CO) 3 ] + complexes containing Tc in oxidation state +1 (Lukens et al. 2004). During the last two years, our team has expanded this work and demonstrated that high-ionic-strength solutions typifying tank waste supernatants promote oxidative stability of the [Tc(CO) 3 ] + species (Rapko et al. 2013; Levitskaia et al. 2014). It also was observed that high-ionic-strength alkaline matrices stabilize Tc(VI) and potentially Tc(IV) oxidation states, particularly in presence organic chelators, suggesting that the relevant Tc compounds can serve as important redox intermediates facilitating the reduction of Tc(VII) to Tc(I). Designing strategies for effective Tc processing, including separation and immobilization, necessitates understanding the molecular structure of these non-pertechnetate species and their identification in the actual tank waste samples. To-date, only limited information exists regarding the nature and characterization of the Tc(I), Tc(IV), and Tc(VI) species. One objective of this project is to identify the form of non-pertechnetate in the Hanford waste. To do this, we are developing a spectral library of reference non-pertechnetate compounds that can be compared against actual waste samples. The emphasis of the fiscal year 2015 work was Tc(I) tricarbonyl [Tc(CO) 3 ] + compounds. The key findings are summarized below.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Operational Plan for Underground Storage Tank 322 R2U2

This Operational Plan provides the operator of the tank system with guidelines relating to the safe and compliant operation and maintenance of the tank system. The tank system schematic and list of emergency contacts shall be posted near the tank so they are visible to tank personnel. This Operational Plan shall be kept on file by the Facility Supervisor. It should be understood when managing this tank system that it is used to store hazardous waste temporarily for 90 calendar days or less. The rinsewater handled in the tank system is considered hazardous and may exhibit the characteristic of toxicity.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Characterization of Non-pertechnetate Species Relevant to the Hanford Tank Waste

Among radioactive constituents present in the tank waste stored at the U.S. DOE Hanford Site, technetium-99 (Tc), which is generated from the fission of 235 U and 239 Pu in high yields, presents a unique challenge in that it has a long half-life ( = 292 keV; T1/2 = 2.11105 y) and exists predominately in soluble forms in the liquid supernatant and salt cake fractions of the waste. In the strongly alkaline environments prevalent in most of the tank waste, its dominant chemical form is pertechnetate (TcO 4 - , oxidation state +7). However, attempts to remove Tc from the Hanford tank waste using ion-exchange processes specific to TcO 4 - only met with limited success, particularly when processing tank waste samples containing elevated concentrations of organic complexants. This suggests that a significant fraction of the soluble Tc can be present as low-valent Tc (oxidation state < +7) (non-pertechnetate). The chemical identities of these non-pertechnetate species are poorly understood. Previous analysis of the SY-101 and SY-103 tank waste samples provided strong evidence that non-pertechnetate can be comprised of [fac-Tc(CO) 3 ] + complexes containing Tc in oxidation state +1 (Lukens et al. 2004). During the last three years, our team has expanded this work and demonstrated that high-ionic-strength solutions typifying tank waste supernatants promote oxidative stability of the [fac-Tc(CO) 3 ] + species (Rapko et al. 2013a; 2013b; Levitskaia et al. 2014; Chatterjee et al. 2015). Obtained results also suggest possible stabilization of Tc(VI) and potentially Tc(IV) oxidation states in the high-ionic-strength alkaline matrices particularly in the presence of organic chelators, so that Tc(IV, VI) can serve as important redox intermediates facilitating the reduction of Tc(VII) to Tc(I). Designing strategies for effective Tc management, including separation and immobilization, necessitates understanding the molecular structure of the non-pertechnetate species and their identification in the actual tank waste samples, which would facilitate development of new treatment technologies effective for dissimilar Tc species. The key FY 2016 results are summarized below.

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

Multi-Cycle Cesium Ion Exchange Testing Using Spherical Resorcinol-Formaldehyde Resin with Diluted Hanford Tank Waste 241-AP-105

Washington River Protection Solutions requested that at least 4 L of Hanford tank waste collected from tank 241-AP-105 and diluted to approximately 5.6 M Na (AP-105DF) be prepared for use in vitrification studies. Cesium removal was required to meet this objective and the waste pretreatment platform, established at Pacific Northwest National Laboratory, was used to create the vitrification feed. The Test Platform mimicked the Low-Activity Waste Pretreatment System (LAWPS) facility planned to pretreat Hanford tank waste supernate by removing solids in a cross flow filter apparatus and processing the supernate through ion exchange columns to remove cesium. At the time of testing, the ion exchange media was targeted to be spherical resorcinol-formaldehyde (SRF) resin. The SRF resin has been tested with a wide array of simulants and process scales, but column performance testing with actual tank waste had been somewhat limited to two Hanford tank wastes (AP-101 and AN-102) in up to two process cycles. This report describes testing conducted in a total of six load elute cycles with the AP-105DF tank waste. The column system was first tested with simulant and was previously described; this report describes the six process cycle results with the AP-105DF tank waste.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗