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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Eruptive Activity on the Western Flank of Piton de la Fournaise (La Réunion Island, Indian Ocean): Insights on Magma Transfer, Storage and Evolution at an Oceanic Volcanic Island

Abstract Petrological and geochemical (major element, trace element, Sr–Nd isotope) data for recent (<5 kyr old) basalts that sporadically erupt on the western flank of Piton de la Fournaise (PdF), one of the most active volcanoes on Earth, allow the tracking of magma transfer and evolution from mantle to crustal depths. In the western peripheral area of PdF we document the broadly synchronous eruptions of (1) primitive olivine and olivine–clinopyroxene transitional basalts with tholeiitic affinity that are closely associated in space with (2) transitional olivine basalts with alkaline affinity, and (3) hybrid lavas, intermediate between the ‘alkaline’ and the ‘tholeiitic’ end-members. The composition of the latter overlaps with that of the lavas frequently erupted from the conduit system feeding the main summit cone. AlphaMELTS modelling, and fluid inclusion and clinopyroxene barometry, constrain the conditions of magma storage at 10–30 km, and the ascent of magma from the upper mantle to the shallow crustal plumbing system. Variable degrees of mantle melting, together with minor source heterogeneity and contamination with cumulate-derived partial melts, contribute to the diversity of PdF magmas. However, all these processes do not represent the dominant factors that produce the large variability we found in major element composition. Indeed, the composition of basalts erupted from PdF peripheral centers is strongly controlled by polybaric olivine–clinopyroxene fractionation at pressures higher than 3 kbar. Crystal textures and geochemical modelling suggest that fast magma ascent is critical to prevent clinopyroxene dissolution. Conversely, long-lasting magma stagnation promotes pyroxene resorption and magma differentiation. ‘Central’ eruptions occurring close to the PdF summit cone emit variably more evolved melts, which result from olivine–clinopyroxene–plagioclase differentiation at intermediate–shallow pressure (<3 kbar and in most cases <1 kbar). Deep and extensive magma mixing before injection into the crustal magma conduit system, located below the summit region, results in the apparent homogeneity of basalts erupted from the central area. As regards ‘peripheral’ eruptions, deep-seated stagnation of basaltic melts and differentiation at the mantle–crust transition zone (c. 4 kbar) produces a range of magma compositions. We demonstrate that rapid magma ascent from deep-seated reservoirs can bypass the central plumbing system. The eruptions of these magmas both in the central area and on the densely populated flanks have major consequences in terms of volcanic hazard at PdF.

Boudoire, G.↗
DOE OSTI2024

Successful cleanroom installation of PIP-II SSR2 coupler using robotic arm

To minimize the contamination of SRF cavities, remote installation techniques are needed during the installation of components. Recent work at Fermilab has been performed to begin the process of developing techniques for assembling cavities using robotics. Multiple alignment methods were prototyped including alignment and computer vision methods. Using a remotely controlled robotic arm, the alignment and installation of couplers have been successfully performed on prototype PIP-II SSR2 cavities in a cleanroom. The installation process will be shown to show to demonstrate the potential of future installations on other cavities and cavity ancillaries.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Innovation 101: The story behind the invention of DNATrax

Lawrence Livermore researcher George Farquar shares the story behind the invention of DNATrax, a cost-effective and highly efficient method to accurately trace contaminated food back to its source. Foodborne illnesses kill roughly 3,000 Americans each year and about 1 in 6 are sickened, according to the Centers for Disease Control and Prevention. Yet most contaminated foods are never traced back to their source. That’s because existing methods to track tainted food following its supply chain from table to farm are highly inefficient, jeopardizing the health of millions and costing the food industry billions. A typical process to trace food includes interviewing consumers and suppliers and examining every detail of the supply chain, a tedious method that takes weeks at best to complete.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Defect and satellite characteristics of additive manufacturing metal powders

Metal additive manufacturing (AM) requires high-quality metal powders to three-dimensionally (3D) print metallic components with complex and customizable geometries. The lack of quantification of AM metal powders creates quality control challenges for 3D printed components, increases the uncertainty of printing reliability and net cost of inspected and certified printed components, and reduces the recyclability of used powders. However, critical characteristics of AM metal powders that are decisive factors for the 3D printing process, such as internal porosity, contamination, and satellite feature, remain ambiguous. In this work, we developed a novel approach to 3D quantify key characteristics of AM metal powders down to individual particles by using high-resolution synchrotron x-ray computed tomography. Empowered by the penetrative capability of high-energy x-ray, internal porosity and contamination within as-atomized metal powders from high-entropy alloys to nickel-based superalloys were evaluated. Additionally, the newly-developed dispersion method enables the homogeneous separation of individual particles, and consequently, results in the implementation of 3D particle shape analysis. To resolve a major challenge of identification and quantification of satellite-feature particles in as-atomized AM metal powders, the satellite features were quantitated by modeling and analyzing the shape parameter of local thickness variance. Furthermore, the 3D analytical methods of particle assessment in this study can be applied to other materials systems like rock, food, and pharmaceutical particles, and provide insights for process optimization across powder metallurgy, concrete, food and pharmaceutical manufacturing, and AM industries.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Facility Improvements and Modifications to Extend the Operational Life of the Modular Caustic-Side Solvent Extraction Process - 16082

Savannah River Remediation, LLC (SRR) is working to remove, stabilize, and dispose of approximately 36.7 million gallons (138.9 million liters) of liquid radioactive waste currently stored in 43 underground waste tanks, and ultimately close waste tanks. In 2008, as an interim salt treatment system to remove cesium from high level waste salt solutions prior to the Salt Waste Processing Facility start up, the Modular Caustic-Side Solvent Extraction Unit (MCU) initiated the removal of cesium from liquid radioactive salt waste prior to disposal. The MCU was designed and built for an expected three-year operational life and five-year design life. The first MCU cold runs began in June 2007 and hot startup was completed in April 2008. MCU remains in hot operation to this day, aiding in multiple, high-level tank closures. In an effort to continue liquid waste disposition at the Savannah River Site (SRS), equipment upgrades and operational improvements have been made to extend the life of the MCU beyond the original three years. Several pieces of fixed equipment have been converted into removable equipment which reduces the downtime associated with equipment change-outs and thereby reduces the dose to workers and processing impacts. Multiple pumps and filters have been upgraded to more robust designs. Process monitoring and controls have been upgraded to improve process performance. Redundant centrifugal contactor vibration equipment has been installed on each contactor in order to better assess the reliability, processing performance, and lifetime of the contactors. A new Solvent Hold Tank (SHT) Sampler has been installed to minimize the organic cross-contamination within the sampler, dose to workers, and sample analysis time. To increase processing availability and aid in visually obtained data, camera port has been added to the Salt Solution Feed Tank (SSFT). In order to decrease the overall background dose to the workers, the Process Vessel Ventilation (PVV) duct work now has the capability to be flushed to remove contamination. The caustic wash addition system has been modified to be a once-through system to improve equipment reliability, decrease downtime, and decrease dose to workers. In addition, the solvent that MCU utilizes to extract Cesium out of salt waste has been upgraded to Next Generation Solvent (NGS) which is based on MaxCalix extractant instead of a BobCalix extractant. Further, these upgrades and improvements have allowed MCU to be able to process at higher flow rates (up to 8.5 GPM) and with increased throughput (as high as 1.3 million gallons in FY13 and 5.3 million gallons since hot operations initiated) that have allowed SRR to continue the disposition of nuclear salt waste. The continued operation of MCU ensures more curies are stabilized into a glass matrix at SRS's Defense Waste Processing Facility (DWPF) and less curies are retained within South Carolina at SRS's Saltstone Disposal Facility (SDF). Unique challenges associated with modifying and improving a demonstration plant that is in hot operations and was designed to be temporary with a limited plant footprint have been successfully overcome. Further, creative strategies for removing old equipment have been utilized given the limited decontamination agents available for use that will not interfere with the organic solvent. This paper presents and discusses the deployment of these upgrades and operational improvements to MCU in order to allow continued, increased salt waste processing beyond the initial design life. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Central Plateau Cleanup at DOE's Hanford Site - 12504

The discussion of Hanford's Central Plateau includes significant work in and around the center of the Hanford Site - located about 7 miles from the Columbia River. The Central Plateau is the area to which operations will be shrunk in 2015 when River Corridor cleanup is complete. This work includes retrieval and disposal of buried waste from miles of trenches; the cleanup and closure of massive processing canyons; the clean-out and demolition to 'slab on grade' of the high-hazard Plutonium Finishing Plant; installation of key groundwater treatment facilities to contain and shrink plumes of contaminated groundwater; demolition of all other unneeded facilities; and the completion of decisions about remaining Central Plateau waste sites. A stated goal of EM has been to shrink the footprint of active cleanup to less than 10 square miles by 2020. By the end of FY2011, Hanford will have reduced the active footprint of cleanup by 64 percent exceeding the goal of 49 percent. By 2015, Hanford will reduce the active footprint of cleanup by more than 90 percent. The remaining footprint reduction will occur between 2015 and 2020. The Central Plateau is a 75-square-mile region near the center of the Hanford Site including the area designated in the Hanford Comprehensive Land Use Plan Environmental Impact Statement (DOE 1999) and Record of Decision (64 FR 61615) as the Industrial-Exclusive Area, a rectangular area of about 20 square miles in the center of the Central Plateau. The Industrial-Exclusive Area contains the 200 East and 200 West Areas that have been used primarily for Hanford's nuclear fuel processing and waste management and disposal activities. The Central Plateau also encompasses the 200 Area CERCLA National Priorities List site. The Central Plateau has a large physical inventory of chemical processing and support facilities, tank systems, liquid and solid waste disposal and storage facilities, utility systems, administrative facilities, and groundwater monitoring wells. As a companion to the Hanford Site Cleanup Completion Framework document, DOE issued its draft Central Plateau Cleanup Completion Strategy in September 2009 to provide an outline of DOE's vision for completion of cleanup activities across the Central Plateau. As major elements of the Hanford cleanup along the Columbia River Corridor near completion, DOE believed it appropriate to articulate the agency vision for the remainder of the cleanup mission. The Central Plateau Cleanup Completion Strategy and the Hanford Site Cleanup Completion Framework were provided to the regulatory community, the Tribal Nations, political leaders, the public, and Hanford stakeholders to promote dialogue on Hanford's future. The Central Plateau Cleanup Completion Strategy describes DOE's vision for completion of Central Plateau cleanup and outlines the decisions needed to achieve the vision. The Central Plateau strategy involves steps to: (1) contain and remediate contaminated groundwater, (2) implement a geographic cleanup approach that guides remedy selection from a plateau-wide perspective, (3) evaluate and deploy viable treatment methods for deep vadose contamination to provide long-term protection of the groundwater, and (4) conduct essential waste management operations in coordination with cleanup actions. The strategy will also help optimize Central Plateau readiness to use funding when it is available upon completion of River Corridor cleanup projects. One aspect of the Central Plateau strategy is to put in place the process to identify the final footprint for permanent waste management and containment of residual contamination within the 20-square-mile Industrial-Exclusive Area. The final footprint identified for permanent waste management and containment of residual contamination should be as small as practical and remain under federal ownership and control for as long as a potential hazard exists. Outside the final footprint, the remainder of the Central Plateau will be available for other uses consistent with the Hanford Comprehensive Land-Use Plan (DOE 1999), while maintained under federal ownership and control. (author)

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DOE OSTI2015

Revealing the Role of Microbes in Controlling Contaminants

In Rifle, Colorado, Berkeley Lab earth scientist, Kenneth Hurst Williams, highlights the role subsurface microbial communities can play in controlling the flow of contaminants in groundwater. The DOE Joint Genome Institute is a key collaborator in the research. Williams is Component Lead of Watershed Structure and Controls within Berkeley Lab's Genomes-to-Watershed Scientific Focus Area.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Streamlined Approach for Environmental Restoration Plan for Corrective Action Unit 574: Neptune, Nevada National Security Site, Nevada

This Streamlined Approach for Environmental Restoration (SAFER) Plan identifies the activities required for closure of Corrective Action Unit (CAU) 574, Neptune. CAU 574 is included in the Federal Facility Agreement and Consent Order (FFACO) (1996 [as amended March 2010]) and consists of the following two Corrective Action Sites (CASs) located in Area 12 of the Nevada National Security Site: (1) CAS 12-23-10, U12c.03 Crater (Neptune); (2) CAS 12-45-01, U12e.05 Crater (Blanca). This plan provides the methodology for the field activities that will be performed to gather the necessary information for closure of the two CASs. There is sufficient information and process knowledge regarding the expected nature and extent of potential contaminants to recommend closure of CAU 574 using the SAFER process. Based on historical documentation, personnel interviews, site process knowledge, site visits, photographs, field screening, analytical results, the results of the data quality objective (DQO) process (Section 3.0), and an evaluation of corrective action alternatives (Appendix B), closure in place with administrative controls is the expected closure strategy for CAU 574. Additional information will be obtained by conducting a field investigation to verify and support the expected closure strategy and provide a defensible recommendation that no further corrective action is necessary. This will be presented in a Closure Report that will be prepared and submitted to the Nevada Division of Environmental Protection (NDEP) for review and approval.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Impacts of Environmental Nanoparticles on Chemical, Biological and Hydrological Processes in Terrestrial Ecosystems

This chapter provides insights on nanoparticle (NP) influence or control on the extent and timescales of single or coupled physical, chemical, biological and hydrological reactions and processes that occur in terrestrial ecosystems. Examples taken from the literature that show how terrestrial NPs may determine the fate of the aqueous and sorbed (adsorbed or precipitated) chemical species of nutrients and contaminants, are also included in this chapter. Specifically, in the first section, chapter objectives, term definitions and discussions on size-dependent properties, the origin and occurrence of NP in terrestrial ecosystems and NP toxicity, are included. In the second section, the topic of the binary interactions of NPs of different sizes, shapes, concentrations and ages with the soil solution chemical species is covered, focusing on NP formation, stability, aggregation, ability to serve as sorbents, or surface-mediated precipitation catalysts, or electron donors and acceptors. In the third section, aspects of the interactions in the ternary systems composed of environmental NP, nutrient/contaminant chemical species, and the soil/sediment matrix are discussed, focusing on the inhibitory and catalytic effects of environmental NP on nutrient/contaminant advective mobility and mass transfer, adsorption and desorption, dissolution and precipitation and redox reactions that occur in terrestrial ecosystems. These three review sections are followed by a short summary of future research needs and directions, the acknowledgements, the list of the references, and the figures.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

The SRNL technical assistance program: transferring lessons learned from two decades of remedial successes to the DOE complex - 15438

The Savannah River Site has an established history of developing implementable risk reduction strategies, developing and deploying innovative technological solutions, and collaboratively achieving realistic and protective environmental end states for complex environmental problems. Part of this success results from the strong historical collaboration between site environmental restoration groups and the Savannah River National Laboratory which results in the promulgation of innovative technical approaches and technologies from the laboratory to ongoing remediation campaigns. Much of the underlying research and development effort was funded by DOE's Office on Environmental Management through a series of applied technology demonstration projects (Integrated Demonstration Project, Integrated Programs and the Applied Field Research Site). Concomitant with the research efforts, SRNL has managed a dynamic and efficient national program that provides teams of technical experts with a broad experience base to recommend strategies that reduce risk and/or technical uncertainty for challenging environmental problems at other DOE facilities. At many of these sites, standard remedial approaches (e.g., excavation, pump and treat, soil vapor extraction) have either failed or proved to be too costly, inadequate, or ineffective. Alternatively, other sites struggle with implementation of innovative but less well understood approaches. The technical assistance teams use a structured process that based on several basic concepts, specifically, development of site specific technical frameworks, and careful matching of remedies to site-specific chemical, geological and physical conditions. Development of technical frameworks is a key strategy to apply basic science to an applied field problem. When directed toward understanding complex real-world environmental remediation challenges, frameworks are tools that support practical identification and incorporation of the key-controlling scientific processes and principles. Frameworks can also be used to minimize technical risks, encourage efficiency and effectiveness, and provide the basis for innovative and creative solutions. Efficient and effective environmental cleanup also requires matching the character of remediation and stabilization methods to the nature of the target zone of contamination as the nature of the target zone evolves through the life of the remedial project. A contaminant plume can be divided into the following zones: the source zone, the impact zone, and the transitional zone that then can be used to identify classes of technologies that are appropriate to that zone. For example, physical and chemical methods (e.g., trapping, immobilization, destruction, or isolation) that directly address the source contaminants are often appropriate for the disturbed zone during the remedial process. A variety of methods that include both active treatments (e.g., pump and treat or active bioremediation) and enhanced attenuation technologies (e.g., geochemical manipulation or reactive barriers) are often suitable for the primary contamination zone or impact zone. Various strategies based on natural attenuation processes may be applicable to the primary contamination zone and these methods are typically applied for the transition or baseline portions of the plume. Careful matching of remedies to site-specific conditions is critical to long-term success in environmental cleanup and restoration. The matching process facilitates selection of technologies with particular strengths that align with real-world needs and constraints, encourages strategic use of multiple or combined technologies to address major plume sub-domains, and supports transitioning technologies in space and time as remediation progresses. Since 2006, the SRNL Technical Assistance program has focused on providing support across the DOE complex. During this time, over 25 teams have visited eleven DOE sites and made recommendations that yielded an estimated cost savings of $100 M. Examples will be provided that illustrate key aspects and significant successes of the technical assistance program. (authors)

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

Model Study and Site Experience of Radiation Physics Analysis for Research Reactor Decommissioning - 18586

The University of Alberta Safe Low Power Kritical Experiment (SLOWPOKE II) nuclear reactor facility (UASF) was commissioned on April 22, 1977. It was designed, built and installed by Atomic Energy of Canada Limited (AECL) and was the fourth SLOWPOKE II research reactor installed at a Canadian university at that time. The reactor was used as a source of neutrons for radionuclide production and elemental analysis via neutron activation analysis, to provide a service to industry, government and to support research and teaching at the University of Alberta. It was licensed to operate at 20 kW, less than the heat produced by a small residential furnace, and work with the reactor was typically performed at one-tenth full power. After nearly four decades of service, the reactor reached the end of its useful life in August 2017 when defueling and the project to decommission the reactor began. Decommissioning of the UASF is a process to dismantle the facility by progressively removing the reactor core and other radioactive components as well as managing the balance of contaminated materials around the reactor in a safe manner. The objective of the project is to release the site from the Canadian Nuclear Safety Commission's (CNSC) regulatory control and return the site to a 'greenfield' status. This paper will discuss the radiation physics analysis that was undertaken to support the decommissioning of the University of Alberta SLOWPOKE II Facility Reactor which took place from July - October 2017. It will address the radiation physics model study, development of the radiation protection (RP) plan, site experience and how the lessons learned from this project can be utilized for best practice on other similar projects. (authors)

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

Outgassing behavior and heat treatment optimization of JSC-1A lunar regolith simulant

As NASA strives towards a long duration presence on the Moon, it has become increasingly important to learn how to better utilize resources from the lunar surface for everything from habitats, vehicle infrastructure, and chemical extraction. To that end, a variety of lunar simulants have been sourced from terrestrially available volcanic minerals and glass as Apollo regolith is unavailable for experimentation needing large masses. However, while mineralogy and chemical composition can approach that of lunar material in these simulants, there are still distinct non-lunar phases such as hydrates, carbonates, sulfates, and clays that can cause simulants to behave distinctly non-lunar in a variety of processing conditions that maybe applied in-situ to lunar material. Notably, severe glassy bubbling has been documented in a variety of vacuum sintering experiments on JSC-1A lunar mare simulant heated via microwaves. The origins of this outgassing have not been well understood but are normally attributed to the decomposition of non-lunar contaminates intrinsic to virtually all terrestrially sourced simulants. As such, a series of controlled environmental tests were performed to ascertain the origins of the high temperature outgassing and to develop heat treatments that can drive JSC-1A closer to lunar composition and behavior. It was found that in JSC-1A at elevated temperatures distinct gas evolutions of water, carbon dioxide, and sulfur dioxide occur in both inert gas and vacuum. Additionally, the presence of hydrogen during heat treatments was shown to dramatically change gas evolutions, leading to distinctly more lunar-like composition and behavior from JSC-1A simulant.

58 GEOSCIENCES↗
DOE OSTI2015

Management of multiple groundwater contaminant plumes extending beyond property boundaries at the young - Rainey STAR Center (Science, Technology, and Research Center) - 15623

The US DOE Pinellas Plant-now known as the Young - Rainey STAR Center, located in Largo, Florida-manufactured components for nuclear weapons from 1956 to 1995. During decades of operations, chlorinated solvents were released from a drum storage area and from underground piping at multiple points adjacent to and beneath a 4.5-hectare (11-acre) building. Two groundwater contaminant plumes associated with contaminant sources beneath the building have been identified, delineated, and are being monitored. During a focused delineation campaign in 2008 to better define the plume boundaries prior to municipal construction projects in the area, the plumes were determined to extend beyond the site boundaries, beneath the adjacent roadway easements, and beneath four adjacent privately owned properties. US DOE has performed a number of activities in response to the discovery of the offsite contaminant plumes, including performing a high-resolution delineation of contaminant plumes; coordinating with local municipalities to complete two linear construction projects requiring dewatering in the vicinity of the plumes; performing risk assessment, risk management, risk communication, and community relations tasks associated with the project; coordinating with state regulators to identify a risk-based corrective action regulatory approach; and coordinating with impacted property owners to develop and implement institutional controls. During the replacement of a 1.2-meter (48-inch) municipal potable water line directly over the contaminant plume area, US DOE (1) constructed infrastructure to receive and treat dewatering effluent at a rate of 20 gallons per minute around the clock for 6 weeks, and (2) conducted breathing-zone air monitoring during excavation of a 3.0-meter (10-foot) deep trench. This degree of diligence was necessary to ensure and document that no site workers were exposed to chlorinated solvent vapors during the construction process, and that a large volume of potentially contaminated groundwater was properly treated and dispositioned. US DOE also took aggressive actions to pro-actively address claims regarding loss of property value on two properties associated with the groundwater contamination, which resulted in a teaming arrangement with each party for future management of the ongoing corrective actions. (authors)

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

Controls of Microstructure and Chemical Reactivity on the Replacement of Limestone by Fluorite Studied Using Spatially Resolved Small Angle X-ray and Neutron Scattering

Fluid-mineral interactions can alter the pore structure and mineral composition of earth materials, sometimes leading to complete replacement of one mineral phase by another. A quantitative understanding of these processes is needed for the prediction of contaminant transport in nuclear waste management, oil and gas exploration, geothermal energy production and in many geological processes. Currently, a detailed understanding of how the original microstructure and chemical reactivity is affecting the replacement rate and porosity development is lacking which would enable the prediction of contaminant transport. Here, we present a systematic experimental study of limestone replacement in the model system calcite-fluorite varying both the texture and chemical reactivity of the parent rock. By combining X-ray ((U)SAXS) and neutron (ultra) small-angle scattering ((U)SANS) we quantified changes in the porosity as a function of depth within the sample and time. By shielding the samples with a set of annular Cd-masks during neutron scattering, we obtained spatially-resolved porosity information. Microstructural changes were investigated using scanning electron microscopy (SEM), and composition changes were accessed using chemical imaging by Time-of-Flight Secondary Ion Mass Spectrometry (ToF—SIMS) and SEM-Energy-Dispersive X-Ray Spectroscopy (SEM-EDX). The replacement of limestone via fluorite takes place via advantageous pathways enhancing the available reactive surface area, e.g. fractures, accessible, interconnected porosity, non-connected porosity grain boundaries and twin boundaries. The results presented in this paper emphasize the importance of a detailed structural and textural assessment of the starting material both in experimental studies and in nature to make accurate predictions about reaction rates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Density of molten oxides measured in an aero-acoustic levitator

Knowing the thermophysical properties of high-temperature melts can aid the design of melt processes and validate atomic structural models, such as those used in studying glass formation. Property measurements on such melts are challenging, however, due to container-related contamination and heterogeneous nucleation. Containerless processing techniques that employ levitation can be used to avoid these obstacles. In that context, we demonstrate here the application of silhouette imaging to measure the density of molten oxides in an aero-acoustic levitation instrument (AAL). The AAL combines gas jet levitation with actively controlled acoustic positioning to enable full optical access to samples ca. 2–4 mm in diameter, which are laser beam heated and melted. The cross sections of molten drops are imaged using a monochromatic light source and narrowband-filtered camera. Melt volume is calculated from the cross sections and used to find density at several temperatures ranging 1530–1920 K, including up to 350 K of supercooling. We report densities for CaAl 2 O 4 , Ca 12 Al 14 O 33 , CaSiO 3 , their Fe 2 O 3 -bearing analogs, and 83TiO 2 -17RE 2 O 3 (RE = La or Nd). These provide important benchmarks of the capabilities, measurement uncertainties, and future outlook for this technique.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Cloud-Enabled Microscopy and Droplet Microfluidic Platform for Specific Detection of Escherichia coli in Water

We report an all-in-one platform – ScanDrop – for the rapid and specific capture, detection, and identification of bacteria in drinking water. The ScanDrop platform integrates droplet microfluidics, a portable imaging system, and cloud-based control software and data storage. The cloud-based control software and data storage enables robotic image acquisition, remote image processing, and rapid data sharing. These features form a “cloud” network for water quality monitoring. We have demonstrated the capability of ScanDrop to perform water quality monitoring via the detection of an indicator coliform bacterium, Escherichia coli, in drinking water contaminated with feces. Magnetic beads conjugated with antibodies to E. coli antigen were used to selectively capture and isolate specific bacteria from water samples. The bead-captured bacteria were co-encapsulated in pico-liter droplets with fluorescently-labeled anti-E. coli antibodies, and imaged with an automated custom designed fluorescence microscope. The entire water quality diagnostic process required 8 hours from sample collection to online-accessible results compared with 2–4 days for other currently available standard detection methods.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Mitigation of Hexavalent Chromium in Storm Water Resulting from Demolition of Large Concrete Structure at the East Tennessee Technology Park - 12286

American Recovery and Reinvestment Act (ARRA) funding was provided to supplement the environmental management program at several DOE sites, including the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. Demolition of the ETTP K-33 Building, the largest building to be demolished to date in Oak Ridge, was awarded to LSRS in FY-2010 under the ARRA program. The K-33 building was an 82 foot tall 2-story structure covering approximately 32 acres. Once this massive building was brought down to the ground, the debris was segregated and consolidated into piles of concrete rubble and steel across the remaining pad. The process of demolishing the building, tracking across concrete debris with heavy equipment, and stockpiling the concrete rubble caused it to become pulverized. During and after storm events, hexavalent chromium leached from the residual cement present in the large quantities of concrete. Storm water control measures were present to preclude migration of contaminants off-site, but these control measures were not designed to control hexavalent chromium dissolved in storm water from reaching nearby receiving water. The following was implemented to mitigate hexavalent chromium in storm water: - Steel wool was distributed around K-33 site catch basins and in water pools as an initial step in addressing hexavalent chromium. - Since the piles of concrete were too massive and unsafe to tarp, they were placed into windrows in an effort to reduce total surface area. - A Hach colorimetric field meter was acquired by the K-33 project to provide realtime results of hexavalent chromium in site surface water. - Three hexavalent chromium treatment systems were installed at three separate catch basins that receive integrated storm water flow from the K-33 site. Sodium bisulfite is being used as a reducing agent for the immobilization of hexavalent chromium while also assisting in lowering pH. Concentrations initially were 310 - 474 ppb of hexavalent chromium in surface water at the out-falls that discharge to nearby receiving water. After implementation of the actions described above, concentrations of hexavalent chromium have been effectively reduced to less than 25 ppb at the out-falls. The LSRS team completed demolition of K-33 five months ahead of schedule, and debris removal was completed three months ahead of schedule. A total of 164,000 tons of steel and concrete from the building demolition, accounting for 13,000 shipments, were disposed to the EMWMF. Because of the high toxicity of hexavalent chromium at low concentrations, hexavalent chromium had to be controlled at ppb levels. Hexavalent chromium contaminant concentrations were successfully reduced by over 90% in surface water discharged from the K-33 demolition site into nearby receiving water. Initial efforts of wind-rowing debris piles and obtaining real-time hexavalent chromium measurements to focus initiatives coupled with placement of steel wool in pools or catch basins had some effectiveness. More significant reductions were obtained as the debris piles were removed/disposed in EMWMF, and treatment of surface water with sodium bisulfite in integrated manholes occurred. (authors)

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