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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.

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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Acetate availability and its influence on sustainable bioremediation of uranium-contaminated groundwater

Field biostimulation experiments at the U.S. Department of Energy's Integrated Field Research Challenge (IFRC) site in Rifle, Colorado, have demonstrated that uranium concentrations in groundwater can be decreased to levels below the U.S. Environmental Protection Agency's (EPA) drinking water standard (0.126 {micro}M). During successive summer experiments - referred to as 'Winchester' (2007) and 'Big Rusty' (2008) - acetate was added to the aquifer to stimulate the activity of indigenous dissimilatory metal-reducing bacteria capable of reductively immobilizing uranium. The two experiments differed in the length of injection (31 vs. 110 days), the maximum concentration of acetate (5 vs. 30 mM), and the extent to which iron reduction ('Winchester') or sulfate reduction ('Big Rusty') was the predominant metabolic process. In both cases, rapid removal of U(VI) from groundwater occurred at calcium concentrations (6 mM) and carbonate alkalinities (8 meq/L) where Ca-UO2-CO3 ternary complexes constitute >90% of uranyl species in groundwater. Complete consumption of acetate and increased alkalinity (>30 meq/L) accompanying the onset of sulfate reduction corresponded to temporary increases in U(VI); however, by increasing acetate concentrations in excess of available sulfate (10 mM), low U(VI) concentrations (0.1-0.05 {micro}M) were achieved for extended periods of time (>140 days). Uniform delivery of acetate during 'Big Rusty' was impeded due to decreases in injection well permeability, likely resulting from biomass accumulation and carbonate and sulfide mineral precipitation. Such decreases were not observed during the short-duration 'Winchester' experiment. Terminal restriction fragment length polymorphism (TRFLP) analysis of 16S rRNA genes demonstrated that Geobacter sp. and Geobacter-like strains dominated the groundwater community profile during iron reduction, with 13C stable isotope probing (SIP) results confirming these strains were actively utilizing acetate to replicate their genome during the period of optimal U(VI) removal. Gene transcript levels during 'Big Rusty' were quantified for Geobacter-specific citrate synthase (gltA), with ongoing transcription during sulfate reduction indicating that members of the Geobacteraceae were still active and likely contributing to U(VI) removal. The persistence of reducible Fe(III) in sediments recovered from an area of prolonged (110 day) sulfate reduction is consistent with this conclusion. These results indicate that acetate availability and its ability to sustain the activity of iron- and uranyl-respiring Geobacter strains during sulfate reduction exerts a primary control on optimized U(VI) removal from groundwater at the Rifle IFRC site over extended timescales (>50 days).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Remediation of AMD using natural and waste material

Acid Mine Drainage (AMD) is highly acidic, sulphate rich and frequently carries a high transition metal and heavy metal burden. These AMD's eventually migrate into streams and rivers and impact negatively on the quality of these water bodies. So it is dire necessary to treat this AMD. Various materials such as ladle furnace slag (LFS), bentonite, zeolite, active carbon and kaolinite are currently available to remove heavy metals from contaminated water. All these materials are capable to rise up the pH value and adsorb heavy metals. The process is divided into two stages; screening test and tank experiment. Screening test is conduct by using Batch Equilibrium Test (BET), X-Ray Fluorescene (XRF) identification also Scanning Electron Microscopic (SEM) characteristic. The results showed that all the concentration of heavy metal are decreasing extremely and pH value rise up except for kaolinite. From screening test only ladle furnace slag, bentonite, zeolite and active carbon are chosen for the tank experiment. Tank experiment design with 18cm (H) X 15cm (L) X 15cm (H) was made by silica glass. All these treatment materials were stirred in the tank for 30 days. Initial pH for all tanks is 2.4 and after 30 days is changing into 6.11, 3.91, 2.98 and 2.71 for LFS, bentonite, active carbon as well as zeolite respectively. LFS is the best material for absorption of Zn, Mn and Cu in the synthetic solution. Meanwhile, bentonite is the best absorbent for Ni, Fe and Cd. The conclusion shows that LFS might have big potentials to control AMD pollution base on neutralize pH resulting in a great improvement in the quality of the water.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1983

Shuttle measured contaminant environment and modeling for payloads. Preliminary assessment of the space telescope environment in the shuttle bay

A baseline gaseous and particulate environment of the Shuttle bay was developed based on the various measurements which were made during the first four flights of the Shuttle. The environment is described by the time dependent pressure, density, scattered molecular fluxes, the column densities and including the transient effects of water dumps, engine firings and opening and closing of the bay doors. The particulate conditions in the ambient and on surfaces were predicted as a function of the mission time based on the available data. This basic Shuttle environment when combined with the outgassing and the particulate contributions of the payloads, can provide a description of the environment of a payload in the Shuttle bay. As an example of this application, the environment of the Space Telescope in the bay, which may be representative of the environment of several payloads, was derived. Among the many findings obtained in the process of modeling the environment, one is that the payloads environment in the bay is not substantially different or more objectionable than the self-generated environment of a large payload or spacecraft. It is, however, more severe during ground facilities operations, the first 15 to 20 hours of the flight, during and for a short period after ater was dumped overboard, and the reaction control engines are being fired.

Scialdone, J. J.↗
NASA NTRS2010

Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

The spacesuit water membrane evaporator (SWME) is being developed to perform the thermal control function for advanced spacesuits to take advantage of recent advances in micropore membrane technology in providing a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. Principles of a sheet membrane SWME design were demonstrated using a prototypic test article that was tested in a vacuum chamber at JSC in July 1999. The Membrana Celgard X50-215 microporous hollow fiber (HoFi) membrane was selected after recent contamination tests as the most suitable candidate among commercial alternatives for HoFi SWME prototype development. A design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype consisting 14,300 tube bundled into 30 stacks, each of which are formed into a chevron shape and separated by spacers and organized into three sectors of ten nested stacks. Vacuum chamber testing has been performed characterize heat rejection as a function of inlet water temperature and water vapor backpressure and to show contamination resistance to the constituents expected to be found in potable water produced by the distillation processes. Other tests showed the tolerance to freezing and suitability to reject heat in a Mars pressure environment.

Bue, Grant C.↗
DOE OSTI2022

Preferential Solute Transport in Low Permeability Zones During Spontaneous Imbibition in Heterogeneous Porous Media

Multiphase flows in porous media|and the associated solute transport processes|are controlled by a combination of gravity, capillary, and viscous forces. Geologic heterogeneity influences flow and transport processes, yet gaps exist in our understanding of how heterogeneity impacts capillary-driven transport, such as during spontaneous imbibition. Here we use positron emission tomography, combined with a newly developed method for conducting spontaneous imbibition experiments, to observe solute transport into low permeability regions during imbibition. Using an experimentally parameterized 2D numerical model, we demonstrate how capillary-driven ow near the imbibition front can carry solutes into low permeability regions. This process displaces solutes from high permeability zones while the cumulative amount of solute in low permeability zones increases- opposite of what is observed under fully saturated solute transport conditions. These results highlight the complex flow and solute transport behavior that arise during multiphase displacements in heterogeneous geologic porous media.

58 GEOSCIENCES↗
NASA NTRS1999

Seasonal Characteristics of Non-Meteorological Radar Reflectivity Returns in Central Florida and Their Impact on TRMM Ground Validation

Radar data quality control is a major component to the Tropical Rainfall Measuring Mission (TRMM) Ground Validation (GV) effort. The quality control algorithm utilizes several adjustable height and reflectivity threshold parameters to remove non-precipitation echoes from ground-based radar data. Spurious radar reflectivity returns not removed during the quality control process may create biases in ground validation rainfall products used to evaluate rainfall measurements retrieved from aboard the TRMM satellite. To better evaluate the performance of the quality control algorithm, WSR-88D radar data from one primary GV site, Melbourne, Florida, are used to determine the seasonal characteristics of non-meteorological radar echoes in cast central Florida during the first year of the TRMM mission. It is demonstrated that unique spurious echo regimes develop throughout the year, leading to different levels of successful non-meteorological echo removal by the quality control algorithm. In addition to the type of non- precipitation echoes present, the success of the algorithm is also greatly dependent upon the amount of precipitation present. Less aggressive attempts to remove non-meteorological echoes must be employed when rain is observed so as not to remove these echoes as well. Therefore, precipitation statistics from ground validation monthly rainfall products will be utilized to further document the quality control algorithm performance. Moreover, these precipitation statistics will be used to demonstrate the relationship between dominant spurious echo regimes and rainfall amount. Finally, monthly statistics of contaminated ground validation radar data will be calculated and the effect on rainfall accumulation products will be discussed.

Robinson, Michael↗
DOE OSTI2016

Dewatering Innovations - 16381

The Liquid and Gaseous Waste Operations (LGWO) project, located at the Oak Ridge National Laboratory, handles wastewater from over 600 generators in 200 facilities. LGWO processes these waters, removing radioactive and chemical contaminants prior to discharge to the environment. Through these processes, LGWO generates various sludges that require dewatering prior to transportation. The original process was very inefficient. It involved placing PVC tubing in the bottom of a 90 ft{sup 3} box and sluicing the sludge into the box. Suction was then applied to the PVC tubes to remove water that would settle out of the material. The old process took several evolutions to drain/decant the liquids, which caused unnecessary worker radiation exposure. The moisture content was Near High Moisture content, which presented the possibility that liquids could be released during transport. Due to this fact, disposal costs were very high. Solutions for the 'Old' disposal process were to use liquid-rated Super Sacks, add additional Absorbent and then have the containers evaluated for liquid at TSDRF, prior to final disposal. This paper will describe the innovative packaging that was developed for the processing of these sludges, the ease with which the process was implemented, the versatility of the system and the cost savings associated with the new process. This system can be used in many other water treatment applications and erosion control. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2005

High Energy Cutting and Stripping Utilizing Liquid Nitrogen

The Aerospace Industry has endeavored for decades to develop hybrid materials that withstand the rigors of mechanized flight both within our atmosphere and beyond. The development of these high performance materials has led to the need for environmentally friendly technologies for material re-work and removal. The NitroJet(TM) is a fluid jet technology that represents an evolution of the widely used, large-scale water jet fluid jet technology. It involves the amalgamation of fluid jet technology and cryogenics technology to create a new capability that is applicable where water jet or abrasive jet (water jet plus entrained abrasive) are not suitable or acceptable because of technical constraints such as process or materials compatibility, environmental concerns and aesthetic or legal requirements. The NitroJet(TM) uses ultra high-pressure nitrogen to cut materials, strip numerous types of coatings such as paint or powder coating, clean surfaces and profile metals. Liquid nitrogen (LN2) is used as the feed stream and is pressurized in two stages. The first stage pressurizes sub cooled LN2 to an intermediate pressure of between 15,000 and 20,000 psi at which point the temperature of the LN2 is about -250 F. The discharge from this stage is then introduced as feed to a dual intensifier system, which boosts the pressure from 15,000 - 20,000 psi up to the maximum operating pressure of 55,000 psi. A temperature of about -220 F is achieved at which point the nitrogen is supercritical. In this condition the nitrogen cuts, strips and abrades much like ultra high-pressure water would but without any residual liquid to collect, remove or be contaminated. Once the nitrogen has performed its function it harmlessly flashes back into the atmosphere as pure nitrogen gas. The system uses heat exchangers to control and modify the temperature of the various intake and discharge nitrogen streams. Since the system is hydraulically operated, discharge pressures can be easily varied over a very wide range providing considerable flexibility for various operations. The NitroJet(TM) is an advance on the nitrogen fluid jet technology initially developed at the Idaho National Engineering Laboratory in Idaho Falls, Idaho. NitroCision(R) first introduced the NitroJet(TM) into a commercial setting in 2003 and there has been considerable interest from many diverse sectors of government and industry since then. While the current system is an industrial system with the size and mass normally associated with industrial applications, a smaller system that is much more compact is being contemplated for those applications that do not need the full capabilities of the larger system. The NitroJet(TM) can be deployed as a fixed or mobile system with multiple end effectors capable of cutting, stripping, cleaning, and surface profiling either in robotic or manual applications.

Hume, Howard↗
DOE OSTI2016

The Effect of Bicarbonate on Autunite Dissolution in the Presence of Shewanella oneidensis under Oxygen Restricted Conditions - 16429

Uranium is a key contaminant at many U.S. Department of Energy sites that served a leading role in the nation's defense for over 50 years. Uranium contamination of soil and groundwater is of great environmental concern due to the toxicological properties of the uranyl species. In an effort to decrease the concentration of soluble uranium, tripolyphosphate injections were identified as a feasible remediation strategy for sequestering uranium in situ in contaminated groundwater at the Hanford Site (WA). The introduction of sodium tripolyphosphate into uranium-bearing porous media results in the formation of uranyl phosphate minerals (autunite) of general formula (X{sub 1-2}[(UO{sub 2})(PO{sub 4})]{sub 2-1}.nH{sub 2}O), where X is a monovalent or divalent cation. The stability of the uranyl phosphate minerals in the subsurface is a critical factor since it determines the long-term effectiveness of the sodium tripolyphosphate injection as a remediation strategy. The behavior of uranium and its mobility in the subsurface are affected by various factors such as the chemistry of pore water, groundwater and soil minerals, the presence of complex-forming ligands, and micro-organisms that thrive under these conditions. Bicarbonate presence in the aqueous phase facilitates uranium desorption from soil and sediments and promotes the release of U(VI) into the aqueous phase, thus increasing uranium mobility in natural waters. In neutral or basic pH conditions, uranium can readily complex with a wide variety of ligands such as carbonate and form soluble uranyl-carbonato complexes such as UO{sub 2}(CO{sub 3}){sub 2}{sup 2-} and UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}. Bicarbonate complexes have been identified in contaminated pore water at the Hanford Site. Furthermore, the presence of bacteria can significantly affect uranium mobility since bacteria may bio-enhance the release of U (VI) from uranyl-phosphate minerals, thus liberating uranium in the aqueous phase in an effort to obtain phosphorous, a vital nutrient for their metabolism. The Columbia River at the site exhibits large stage variations, causing fluctuations in the water table. These water table fluctuations and multiple rise-and-fall cycles in the river created an oxic-anoxic interface in this region. Previous assessments of Hanford sediment samples collected from this area noted a decline in cultivable aerobic bacteria and suggested the presence of facultative anaerobic bacteria. Shewanella oneidensis MR1 is a common bacterial group in soils and Shewanella species have been found in the Hanford soil. Shewanella oneidensis is a facultative anaerobic species which also belongs to a group known as dissimilatory metal-reducing bacteria (DMRB), due to their ability to reduce metals as a part of their metabolic pathway. Therefore, understanding the role of Shewanella is a critical factor affecting the outcome of environmental remediation. The objective of this research was to demonstrate the significance of bacteria-uranium interactions and investigate the effect of bicarbonate in the aqueous phase on Ca-autunite dissolution in the oxygen-restricted conditions. Sterile 100-mL glass mixed bioreactors with weighed amounts of ground Ca-autunite particles were used for initial experimentation. These autunite-containing bioreactors were injected with bacterial cells after the autunite equilibrated with the media solution amended with 0 mM, 3 mM 5 mM and 10 mM concentrations of bicarbonate. Additional abiotic samples were prepared without bacterial inoculation to provide a control for the biotic samples. The concentration of U(VI) determined in the aqueous phase was in direct correlation to the concentration of bicarbonate present in the solution. It was noted that an increase in bicarbonate concentration led to higher U(VI) concentration in the aqueous phase. A sharp decrease in U(VI) concentration was observed in the bicarbonate-free samples, probably due to a microbe mediated reduction of U(VI) to U(IV). In the case of samples amended with 3 mM bicarbonate, a slight, yet significant, decrease in U(VI) was also observed compared to the abiotic control. However, compared to the abiotic controls, there was no change in U(VI) levels in the aqueous phase as a result of bacterial inoculation for the samples amended with 5 and 10 mM bicarbonate for a period of time as long as 50 days. These results imply that the uranyl-carbonate complexes (UO{sub 2}(CO{sub 3}){sub 2}{sup 2-} and UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}) that are present in carbonate-rich environments might be interfering with the microbial reduction in the oxygen- restricted conditions; however, this conclusion requires further investigation. Finally, the data indicate that release of U, P and Ca from autunite was non-stoichiometric. In conclusion, the high stability of uranyl-phosphate complexes makes them a strong candidate for the remediation efforts to sequester uranium in the subsurface. Nevertheless, in a bicarbonate-rich environment, Ca-autunite has a high probability of dissolution and the presence of metal-reducing bacteria does not seem to impede this process in the presence of higher bicarbonate concentrations under oxygen restricted conditions. (authors)

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

Challenges of Remote Handling in Windowless Hot Cells - 18341

Facilities such as nuclear power stations and neutron sources produce radioactive waste, which must be handled in shielded containment chambers [hot cells]. Traditionally these hot cells are built with lead glass windows to allow direct observation by operators, however, as the complexity and size of handling operations increases, the restrictions imposed by such windows becomes problematic. For the International Thermonuclear Experimental Reactor [ITER] under construction in the South of France and the European Spallation Source [ESS] under construction in Lund, Sweden the hot cell must be capable of processing large, activated and contaminated components, requiring the dexterous tele-manipulation of high dose payloads in the cell. Using lead glass windows would severely restrict the operational envelope within the cell to the volumes directly in front of the windows. This places unreasonable constraints on the types of handling operations that can be carried out. Conversely, a windowless configuration is much more flexible and maximises the operational space for robotic manipulators. Windowless hot cells do however introduce their own challenges. This paper examines the difficulties introduced by lack of direct sight and describes solutions to overcome them. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Metagenome-assembled genomes from soil samples in control and warming plots in Blodgett Forest, CA (2014-2021)

The pathways of carbon transport and loss through and from soils—soil organic matter (SOM) depolymerization to dissolved organic carbon and mineralization to carbon dioxide (CO2)—are fundamentally driven by microbial activity, which is strongly regulated by environmental conditions. As part of LBNL (Lawrence Berkeley National Laboratory) TES (Terrestrial Ecosystem Science) Belowground Biogeochemistry Science Focus Area (SFA), we have established a novel whole-soil long-term warming experiment at the University of California (UC) Blodgett Forest Research Station (Sierra Nevada) in 2014, where we study the role of biogeochemical, microbial and geochemical process interactions in SOM decomposition and stabilization.Here, we present metagenome-assembled genomes (MAGs) for the bacterial and archaeal community from soil depth profiles collected from 2014 to 2021 from three paired control and warming plots. We collected soil samples across a range of depth profiles (spanning surface to 90 cm deep) from three paired control and warming plots from a temperate mixed forest in Northern California. Each paired plot had been subjected to experimental warming since June 2014 to simulate a predicted climate change scenario for northern California. 101 soil metagenomes were sequenced at JGI (Joint Genome Institute) and UCSF (University of California San Francisco) Center for Advanced Technology and can be found under the JGI (Joint Genome Institute) GOLD (Genomes Online Database) Sequencing project Gs0151586 and NCBI (National Center for Biotechnology Information) Projects PRJNA1225762 and PRJEB39497. Metagenomes were assembled using JGI (Joint Genome Institute) Metagenome Workflow (10.1128/mSystems.00804-20). For each metagenome, the assembled contigs were binned into genomes using 3 binning algorithms (cocacola, metabat, and maxbin) and the resulting bins were consolidated using dastool. The consolidated bins from all metagenomes were pooled, filtered by completeness (>50%) and contamination (<25%), and dereplicated at 99% ANI (average nucleotide identity) using dRep (https://github.com/MrOlm/drep).The dataset includes a zip file of 2321 MAG (Metagenome Assembled Genome) fasta files, the accession numbers for the underlying metagenomes, and a csv file with MAG (Metagenome Assembled Genome) quality metrics and taxonomic classification (GTDB -Genome Taxonomy Database-RS220). This dataset also includes a file-level metadata (flmd.csv) file that lists each file contained in the dataset with associated metadata and a data dictionary (dd.csv) file that contains column/row headers used throughout the files along with a definition, units, and data type. A sample metadata file (samples.csv) that contains site information has also been included.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Dissolution Behavior of Iron and Steel Materials in Liquid Magnesium

The dissolution of metallic elements from Fe and steel materials into pure liquid Mg was investigated with the aim of improving control of impurities in Mg during processes such as Mg-alloy production and Ti smelting. Pure Mg was melted between 1073 and 1323 K (800 and 1050 °C) for 24 to 96 hours in closed crucibles made of pure Fe, low-carbon steel, or austenitic stainless steel SUS316. From the experiments using the pure Fe crucible, the relationship between the solubility of Fe in liquid Mg [C{sub sol,Fe} (mass pct)] and temperature [T (K)] was determined to be log(C{sub sol,Fe}) = − 3.67 × 10{sup 3}/T + 2.48 (± 0.06), from which the standard Gibbs energy of Fe dissolution in liquid Mg was evaluated. The amount of Fe dissolved from low-carbon steel was the same as that from pure Fe. From SUS316, not only Fe but also Cr and Ni dissolved into liquid Mg; the Fe and Cr concentrations in liquid Mg did not change significantly over time, whereas the Ni concentration increased monotonically. Preferential Ni dissolution resulted in a Ni-poor layer on the SUS316 surface. Finally, using the experimental data of Fe dissolution from low-carbon steel, the Fe contamination route in the current Ti smelting process, where a large amount of Mg is used as a reducing agent, is discussed.

36 MATERIALS SCIENCE↗
NASA NTRS2013

Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts. Preferably, the hydrogenation catalyst is a bimetallic particle formed from a zero-valent iron or zero-valent magnesium particle coated with palladium that is impregnated onto a high-surface-area graphite support. The zero-valent metal particles should be microscale or nanoscale zero-valent magnesium or zero-valent iron particles. Other zero-valent metal particles and combinations may be used. Additionally, the base material may be selected from a variety of minerals including, but not limited to, alumina and zeolites. The catalytic metal is preferably selected from the group consisting of noble metals and transition metals, preferably palladium. The mechanical milling process includes milling the base material with a catalytic metal impregnated into a high-surface-area support to form the hydrogenation catalyst. In a preferred mechanical milling process, a zero-valent metal particle is provided as the base material, preferably having a particle size of less than about 10 microns, preferably 0.1 to 10 microns or smaller, prior to milling. The catalytic metal is supported on a conductive carbon support structure prior to milling. For example, palladium may be impregnated on a graphite support. Other support structures such as semiconductive metal oxides may also be used.

Quinn, Jacqueline↗
DOE OSTI2018

Hydrogen Sensor for Parabolic Trough Expansion Tanks

The National Renewable Energy Laboratory and Acciona Energy North America are developing and implementing a process that addresses the issue of hydrogen buildup in parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks of the power plant to control hydrogen levels in the circulating heat-transfer fluid. As part of this effort, we are developing a sensor that measures hydrogen partial pressure in the expansion-tank headspace gas. During previous work, we demonstrated that our sensor design measures hydrogen levels over a wide partial pressure range from 1.33 mbar down to 0.003 mbar with an accuracy of +/-20%. We acquired these results under limited conditions because we measured hydrogen partial pressure in gas mixtures of hydrogen and nitrogen only. In this paper, we report our most recent results in which we measured hydrogen partial pressures in gas mixtures that contain hydrogen, nitrogen, biphenyl, and diphenylether. Our results for this gas mixture were essentially the same as those obtained for the hydrogen/nitrogen mixture only, and they also had the same accuracy of +/-20%. This level of accuracy is sufficient to evaluate the performance of a hydrogen mitigation process because hydrogen partial pressure in the expansion tank decreases more than an order of magnitude when the mitigation process is operating. We examined the palladium/silver membrane after completing these measurements and did not observe any signs of membrane deterioration or contamination due to exposure to biphenyl and diphenylether at 405 degrees C. The membrane for these tests was 25 um thick. For the next sensor design that we are developing in 2018, we are using a membrane that is 127 um thick. This thickness is required for the membrane to withstand the 150 psi pressure drop across the membrane when exposed to actual headspace gas from the expansion tank. We performed initial tests in which we exposed a 127-um-thick palladium alloy membrane to 400 degrees C and 150 psi pressure drop and observed no signs of failure or gas leakage. Finally, we developed a transient model that accounts for hydrogen transport mechanisms within the sensor when measurements are made. Our model accounted for hydrogen diffusion through the boundary layer that is adjacent to the membrane and for hydrogen permeation across the membrane and into the permeate volume. Our modeling results agreed very closely with our experimental data when we assumed a boundary-layer thickness of 0.2 cm. This thickness is within the range of expected thicknesses for this gas composition, temperature, and pressure at minimum flowrate. Our model results showed that hydrogen diffusion through the boundary layer adjacent to the membrane is the rate-determining step for the transient pressure response when measuring hydrogen partial pressure.

14 SOLAR ENERGY↗
DOE OSTI2019

A Comparison of GoldSim, RESRAD-Onsite, and NORMALYSA Modeling Tools at Radioactive Waste Sites - 19480

Radioactive waste disposal and associated decision making is a challenging problem around the world. A strong performance assessment model plays a crucial role in making good management and remediation decisions and in optimizing the performance of a site. The International Atomic Energy Agency (IAEA) MODARIA II Working Group 1 (WG1) is comparing the performance of various modeling platforms used at Naturally Occurring Radioactive Material (NORM) and legacy waste sites to support risk-informed decision making. Neptune and Company, Inc. (Neptune) has developed probabilistic performance assessment models using the GoldSim system modeling software at a variety of radioactive waste sites. This paper presents a comparison between GoldSim and two other tools used to evaluate radiation exposure and their associated risks: the NORM And Legacy Site Assessment (NORMALYSA) tool used to assess risk at the Zapadnoe mill tailings site, and the residual radioactivity (RESRAD-Onsite) computer program used to calculate Authorized Limits at the Los Alamos National Laboratory (LANL). The International Atomic Energy Agency (IAEA) supported development of NORMALYSA based off of Ecolego 6.0, in which the user connects several universal modules, representing various environmental transport and exposure pathways, and enters in site-specific data. Further work with NORMALYSA has continued under the MODARIA II WG 1. A radionuclide transport and dose calculation model of the Zapadnoe uranium mill tailings site at the Pridneprovsky Chemical Plant in the Ukraine has been configured by MODARIA II WG1 to test the capabilities of NORMALYSA. Under this test case, contaminant transport and effective dose calculations were performed for two exposure scenarios. The onsite worker is exposed via external ground irradiation and radon and radioactive dust inhalation. The offsite resident defines a residence established 300 years after institutional control has ended, 800 meters downstream from the site with exposure pathways including: ingestion of garden vegetables irrigated by contaminated ground water, ingestion of fish from the Konoplyanka River and agricultural activities in the contaminated garden. GoldSim modeling software is a dynamic probabilistic modeling platform that evaluates uncertainty in a robust and transparent manner. Although GoldSim provides contaminant and radionuclide transport modules to facilitate integrated modeling of radionuclide migration in the environment, these features are not embedded in an existing modeling framework, except as created by the user. Neptune developed a GoldSim model for the two exposure scenarios of the Zapadnoe test case. Neptune's Generic PA Model was used as a starting point for the Zapadnoe site. Input parameters for the GoldSim model include site-specific parameters from the MODARIA Working Group as well as parameters from the Generic PA Model and other PA models created by Neptune. For the other comparison, Version 7.0 of RESRAD-Onsite, developed by Argonne National Laboratory for the U.S. Department of Energy (DOE), was used to calculate Authorized Limits for LANL. Authorized Limits are concentrations of radionuclides in soil that support the evaluation process to clear land for release under different uses. The RESRAD-Onsite computer code was used to calculate Authorized Limits because this program was specifically designed to derive radionuclide soil guidelines corresponding to a specific dose criterion. The scope of the RESRAD dose or risk evaluation is constrained to the transport and exposure pathways that have been included in the computer code. To assist in illustrating the capability of GoldSim modeling software, a GoldSim model was created to replicate the calculation of LANL's Authorized Limits for soil. The main exposure pathways in this model are inhalation of dust and gas, plant ingestion, soil ingestion, and external ground irradiation. All of the processes and outputs of RESRAD-Onsite and NORMALYSA can be created in a GoldSim model, but the value of GoldSim lies in its flexibility for application to any of a wide variety of environmental modeling problems. GoldSim allows development of site-specific inventory, transport mechanisms and risk assessment scenarios. If all potentially complete release, transport, and exposure pathways are addressed in an existing dose and risk assessment computer code, and if the code's capabilities fulfill the project modeling objectives, then expending resources to create a GoldSim model may not be necessary. Site optimization and good decision making about site management are often best when supported with the flexibility of GoldSim as a modeling tool. (authors)

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

Demonstration of an Ultra-Short Channel Metal Monolith Catalytic Reactor for Trace Contaminant Control Applications

The International Space Station (ISS) Trace Contaminant Control Subassembly (TCCS) design is based upon proven, highly reliable technology. However, because its core unit operations rely upon expendable activated charcoal and an indirectly heated high temperature catalyst, annual logistics mass, crew time, and power consumption requirements are significant. To address this situation, a unique catalytic reactor design has been developed which is suitable for retrofit into the TCCS's high temperature catalytic oxidizer (HTCO) assembly. The unique design, which employs a metallic, ultra-short channel length monolith (USCM) catalyst substrate, was tested in a flight-like TCCS HTCO assembly to investigate its performance characteristics. Test results indicate that retrofitting the TCCS with a USCM-based catalytic reactor is feasible and that it may provide significant reductions in logistics mass, crew time, and power consumption. Savings indicated by test results are up to 81% for annual logistics, 56% for crew time, and 77% for startup transient duration. In addition, its demonstrated ability to operate in a power saving mode provides up to a 43% savings in average power consumption. A summary of the USCM demonstration test objectives, approach, results, and specific benefits to the TCCS's process economics are presented,

Perry, J. L↗
DOE OSTI2020

FX Hg Fogging Fixative Deployment for Mercury Vapor Suppression - 20410

Idaho National Laboratory's (INL) FX Hg fixative solution was deployed at the Y-12 National Security Complex in Oak Ridge, Tennessee to support disposal of mercury-contaminated metal debris. The fixative was dispensed via fogging. Fogging infiltrates non-line-of-sight areas improving fixative coating on complex geometries such as debris piles. FX Hg is the mercury vapor controlling derivative of INL's FX2 fixative. FX2 was jointly developed with the National Nuclear Laboratory of the United Kingdom, and INL developed the FX Hg derivative to suppress mercury vapor generation. The Y-12 deployment was performed in concert with UCOR (URS CH2M Oak Ridge), the cleanup contractor for Y-12. A dumpster filled with debris was fogged with FX Hg. The debris was acceptable as municipal landfill waste, save for the mercury vapor levels measured. If the mercury vapor generation rate could be sufficiently reduced, disposal costs for this waste would be dramatically reduced. FX Hg had previously proven effective at significantly reducing mercury vapor generation rates in bench scale testing at INL. This deployment was the first field-scale deployment of the method. Efficacy results were underwhelming, but interpretation of the outcome is complicated by a paucity of hard data. Methods for improving data capture and analysis are analyzed. Operational difficulties associated with scaling up the process and process improvements for future deployments are discussed. (authors)

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DOE OSTI2016

The Little Engine That Could: No Project is too Small for Sustainable Remediation Moab Uranium Mill Tailings Removal Project - 16427

Executive Order 13693, 'Planning for Federal Sustainability in the Next Decade', mandates the reduction of energy use and cost and greenhouse gas emissions, and the search for renewable or alternative energy solutions. DOE EM manages the Moab Uranium Mill Tailings Remedial Action Project in Utah that involves relocating a 16-million-ton uranium mill tailings pile and associated contaminated materials at the former Atlas mill site to a permanent disposal cell constructed near Crescent Junction, Utah, predominantly by rail. Project personnel strive to support the Executive Order in making preparations for the impacts of climate change. Meeting the goals of the Executive Order in light of the remote location and limited resources of the Project sites often requires an innovative approach and perseverance. The Moab Project is a 'Small Site' within EM and has a comparatively short-term completion date. As a result, large-scale sustainability projects, such as retrofits or remodels, do not offer a cost benefit over this period. Instead, less dramatic process changes are achievable. The Project purchases renewable wind energy through the local power provider to reduce Scope 2 (purchased electricity) greenhouse gas emissions. Toward its ambitious goal of achieving zero landfill waste, the Project has diverted over 50 percent of its nonhazardous solid waste from the local landfill through composting and recycling efforts. In particular, electronics must meet various sustainable criteria prior to purchase, and be recycled through donations and certified recyclers, diverting it from the waste stream. The Project has received multiple Green Buy Awards from DOE by reaching leadership goals for purchasing energy-efficient, water-efficient, bio-based, and recycled-content products. In fiscal year 2014, in response to President Obama's June 2014 memorandum, 'Sustainable Practices for Designed Landscapes and Supporting Pollinators on Federal Landscapes', the Project decided to take a proactive approach and work with a local pollinator group, hosting two beehives in a revegetation area on the Moab site. An increase in plant growth and blossoming plants in the revegetation area has been observed and is believed to be related to the added pollinators. The Project has previously seeded disturbed areas mainly with native drought-resistant species to reduce water usage. Storm water collected in sediment basins at the Crescent Junction site is used for dust control and compaction of mill tailings in the disposal cell. The Project worked with the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service to gain support for re-contouring a remediated area adjacent to the Colorado River, which borders the Moab site on the east, to allow the area to flood at a lower river stage. This re-contouring promotes more varied vegetation growth and river water that tops the west bank brings soil nutrients to inundated areas of the site. Ponded floodwater has been pumped into revegetation plots for irrigation, reducing freshwater usage. Innovation in sustainable practices comes in many different fashions. The Moab Project demonstrates that no project is too small to implement sustainable practices. (authors)

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