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United States Department of Energy Environmental Management Science Program

Works: 1,087 works in 1,632 publications in 1 language and 5,332 library holdings
Roles: Researcher, Sponsor
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Colloid-Facilitated Transport of Radionuclides through the Vadose Zone ( )
9 editions published between 2001 and 2006 in English and held by 11 WorldCat member libraries worldwide
This project seeks to improve the basic understanding of colloid and colloid-facilitated transport of Cs in the vadose zone. The specific objectives are: (1) Determine the structure, composition, and surface charge characteristics of colloidal particles formed under conditions similar to those occurring during leakage of waste typical of Hanford tank supernatants into soils and sediments surrounding the tanks. (2) Characterize the mutual interactions between colloids, contaminant, and soil matrix in batch experiments under various ionic strength and pH conditions. We will investigate the nature of the solid-liquid interactions and the kinetics of the reactions. (3) Evaluate mobility of colloids through soil under different degrees of water saturation and solution chemistry (ionic strength and pH). (4) Determine the potential of colloids to act as carriers to transport the contaminant through the vadose zone and verify the results through comparison with field samples collected under leaking tanks. Results of this project will help to understand the fundamental mechanisms of Cs transport under the leaking Hanford tanks, and thus contribute to the long-term clean-up strategies at the Hanford site
Ecological Interactions Between Metals and Microbes ( )
7 editions published between 1998 and 2005 in English and held by 11 WorldCat member libraries worldwide
Distinct microbial communities had been found in contaminated soils that varied in their concentrations of Pb, Cr and aromatic compounds. It is difficult to distinguish between their effects as their presence is highly correlated. Microcosms were constructed in which either Pb{sup +2} or CrO{sub 4}{sup -2} was added at levels that produced acute modest or severe acute effects (50 or 90% reduction). We previously reported on changes in microbial activity and broad patterns of Bacterial community composition. These results showed that addition of an organic energy source selected for a relatively small number of phylotypes and the addition of Pb or Cr(VI) modulated the community response. We sequenced dominant phylotypes from microcosms amended with xylene and Cr(VI) and from those with the simple addition of glucose only. In both cases, the dominant selected phylotypes were diverse. We found a number of distinct Arthrobacter strains, as well as several Pseudomonas spp. In addition, the high GC-content bands belonged to members of the genera Nocardioides and Rhodococcus. The focus of amended microcosm work has now shifted to anaerobic processes. The reduction of Cr(VI) to Cr(III) as a detoxification mechanism is of greater interest, as is the specific role of particular physiological groups of anaerobes in mediating Cr(VI) detoxification. The correlation between microbial activity, community structure, and metal level has been analyzed on 150 mg of soil collected at spatial scales <1, 5, 15 and 50 cm. There was no correlation between metal content and activity level. Soils <1 cm apart could differ in activity 10-fold and extractable Pb and Cr 7-fold. Therefore, we turned to geostatistical analysis. There was spatial periodicity which is likely to reflect the heterogeneous distribution of active microbes and metal contaminants. Variograms indicated that the range of spatial dependence was up to 20 cm. To visualize the spatial relationships between the primary variate (activity) and its covariates (lead and chromium content), block kriging was used. The kriging maps suggest that areas exist where increased metal concentrations have zones of decreased metabolic microbial activity. Cr(VI) resistant bacteria have been isolated from two contaminated sites. Most isolates are Arthrobacter, Rhodococcus, or Pseudomonas spp. A chrA gene has been cloned from Arthrobacter strain CR15 isolated from Cannelton, MI. PCR-primers have been produced against conserved motifs analyzed from 8 chrA sequences. Of the 96 Cr-resistant isolates from Cannelton, 85% gave a positive reaction to these primers. In contrast, none of the 38 isolates from Seymour, IN were positive. Therefore, at least for the culturable community, a particular resistance determinant appears to be widespread at a geographical site but rare (absent) at another site. The phylogenetic relatedness of the Arthrobacter strains is being evaluated via the distribution of repetitive elements as well as genome-wide restriction fragment analysis. Work to date on the latter has also suggested that Arthrobacter genomes are small (<2.5 Mbp). Gene capture experiments demonstrated that chromate-sensitive Gram-negative bacterial strains could obtain resistance from Cr-contaminated soil. However, frequency of transfer is low (10-6-10-8). Genetic diversity of the acquired chromate resistance mechanism is being assessed
Next Generation Extractants for Cesium Separation from High-Level Waste From Fundamental Concepts to Site Implementation ( )
8 editions published between 2001 and 2005 in English and held by 11 WorldCat member libraries worldwide
This project seeks a fundamental understanding and major improvement in cesium separation from high-level waste by cesium-selective calixcrown extractants. Systems of particular interest involve novel solvent-extraction systems containing specific members of the calix[4]arene-crown-6 family, alcohol solvating agents, and alkylamines. Questions being addressed bear upon cesium binding strength, extraction selectivity, cesium stripping, and extractant solubility. Enhanced properties in this regard will specifically benefit applied projects funded by the USDOE Office of Environmental Management to clean up sites such as the Savannah River Site (SRS), Hanford, and the Idaho National Environmental and Engineering Laboratory. The most direct beneficiary will be the SRS Salt Processing Project, which has recently identified the Caustic-Side Solvent Extraction (CSSX) process employing a calixcrown as its preferred technology for cesium removal from SRS high-level tank waste
The Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance ( )
7 editions published between 2001 and 2005 in English and held by 10 WorldCat member libraries worldwide
This project involves the design and synthesis of receptors for oxoanions of environmental importance and specifically those found in high level waste tanks. Polyammonium macrocycles as receptors and nitrate as anion were the focus of the first phase of this project. A second phase involved the synthesis of lipophilic amide-based receptors in order to increase the potential for obtaining workable receptors for both separations and sensing applications on site. A three tier approach was employed: I. Design, synthesis, and physical and structural characterization of receptors; II. Examination of the technique known as ITIES, Interface Between Two Immiscible Electrolyte Solutions, as an analytical probe for anion analysis; and III. Investigation of dual ion pair extraction using lipophilic amide receptors for anion binding. More recent efforts in the renewal of this project are focusing on sulfate and new designs for receptors. These efforts will also have impact on low activity waste, for example in the vitrification process
Microbial Transformations of Tru and Mixed Wastes Actinide Speciation and Waste Volume Reduction ( )
6 editions published between 2003 and 2006 in English and held by 10 WorldCat member libraries worldwide
Work has been performed in two areas; the interaction of uranium with bacteria and the complexation of metal ions with cellulose degraded by bacteria
Computational Design of Metal Ion Sequestering Agents ( )
7 editions published between 2002 and 2006 in English and held by 10 WorldCat member libraries worldwide
Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort
Speciation, Dissolution, and Redox Reactions of Chromium Relevant to Pretreatment and Separation of High-Level Tank Wastes ( )
6 editions published between 1999 and 2006 in English and held by 10 WorldCat member libraries worldwide
Chromium, one of the problematic elements in tank sludges, is considered the most important constituent in defining the total volume of high-level radioactive waste (HLW) glass. Current sludge-washing processes (e.g. caustic leaching, 3 M NaOH) are not effective in removing Cr. Such inefficient removal would result in the production of an unacceptably large volume of HLW glass and thus a tremendous increase in the cost of waste disposal. This proposed research seeks to develop fundamental data for chromium (Cr) reactions that are not currently available but are essential for developing effective methodologies for removing Cr form high-level waste (HLW). Our objectives are to study (1) the dissolution of several solid phases (e.g., CrOOH, Cr2O3(c), Cr(OH)3, and Fe and Cr, binary hydroxides, identified to be important from sludge leaching studies) in highly alkaline solutions and in the presence of other electrolytes (e.g., carbonate, phosphate, sulfate, nitrite), and (2) the effect of the nature of Cr solid phases and aqueous species on their redox reactivity with a variety of potential oxidants (H2O2, persulfate, hypochlorite, etc.). This information will provide critical support for developing enhanced pretreatment strategies for removing Cr from HLW and will achieve a major cost reduction in HLW disposal
Stability of High-Level Waste Forms ( )
6 editions published between 1999 and 2006 in English and held by 10 WorldCat member libraries worldwide
The objective of the proposed effort is to use a new approach to develop solution models of complex waste glass systems and spent fuel that are predictive with regard to composition, phase separation, and volatility. The effort will also yield thermodynamic values for waste components that are fundamentally required for corrosion models used to predict the leaching/corrosion behavior for waste glass and spent fuel material. This basic information and understanding of chemical behavior can subsequently be used directly in computational models of leaching and transport in geologic media, in designing and engineering waste forms and barrier systems, and in prediction of chemical interactions
Ion Recognition Approach to Volume Reduction of Alkaline Tank Waste by Separation of Sodium Salts ( )
6 editions published between 2002 and 2006 in English and held by 10 WorldCat member libraries worldwide
The overall goal of this research conducted under the auspices of the USDOE Environmental Management Science Program (EMSP) is to provide a scientific foundation upon which the feasibility of new liquid-liquid extraction chemistry applicable to the bulk reduction of the volume of tank waste can be evaluated. Disposal of high-level nuclear waste is horrendously expensive, in large part because the actual radioactive matter in the tanks has been diluted over 10,000-fold by ordinary inorganic chemicals. Quite simply, if the radioactive matter and bulk inorganic chemicals could be separated into separate streams, large cost savings would accrue, because the latter stream is much cheaper to dispose of. In principle, one could remove the radionuclides from the waste, leaving behind the bulk of the waste; or one could remove certain bulk chemicals from the waste, leaving behind the radionuclides. The preponderance of effort over the past two decades has focused on the former approach, which produces a high-level stream for vitrification and a low-activity stream for either vitrification (Hanford) or grout (Savannah River). At Hanford, a particular concern arises in that vitrification of a large volume of low-activity waste will be unacceptably expensive. To make matters worse, a projected future deficit of tank space may necessitate construction of expensive new tanks. These problems have raised questions as to whether a solution could be devised based on separation of sodium from the waste, resulting in the reduction of the total volume of waste that must be vitrified
Radioanalytical Chemistry for Automated Nuclear Waste Process Monitoring ( )
6 editions published between 2002 and 2005 in English and held by 9 WorldCat member libraries worldwide
This research program is directed toward rapid, sensitive, and selective determination of beta- and alpha-emitting radionuclides such as 99Tc, 90Sr, and trans-uranium (TRU) elements in low-activity waste (LAW) processing streams. The overall technical approach is based on automated radiochemical measurement principles, which entails integration of sample treatment and separation chemistries and radiometric detection within a single functional analytical instrument. Nuclear waste process streams are particularly challenging for rapid analytical methods due to the complex, high-ionic-strength, caustic brine sample matrix, the presence of interfering radionuclides, and the variable and uncertain speciation of the radionuclides of interest. As a result, matrix modification, speciation control, and separation chemistries are required for use in automated process analyzers. Significant knowledge gaps exist relative to the design of chemistries for such analyzers so that radionuclides can be quantitatively and rapidly separated and analyzed in solutions derived from low-activity waste processing operations. This research is addressing these knowledge gaps in the area of separation science, nuclear detection, and analytical chemistry and instrumentation
Metal Ion Analysis Using Near-Infrared Dyes and the ''Laboratory-on-a-Chip'' ( )
7 editions published between 1999 and 2004 in English and held by 9 WorldCat member libraries worldwide
The primary research objective of this effort is to develop a portable, capillary electrophoresis microchip capable of sensitively and rapidly monitoring hazardous waste metal ions critical to the successful deactivation and decommissioning (D & D) of contaminated equipment and structures at various DOE sites. Hazardous waste metal ions to be adapted for sensing on the microchip include UO2 2+, Be2+, Cr6+, Hg2+, Pb2+, Co2+, Ni2+, Cs+, and Sr2+. Particular emphasis will be placed on developing viable, new extraction methods for metal ion sampling from both the air via a microimpinger which is integrated onto the microchip itself, and from contaminated surfaces, both techniques being amenable to on-line introduction onto the microchip. Two different detection methods for monitoring the electrophoretic separations taking place down the microchannel will be exploited in this research, indirect and direct detection. Special emphasis will be placed on maintaining the ultimate portability of the final microchip device through the careful selection of metallochromic dyes and fluorophores which are amenable to use of small, inexpensive light sources (e.g., LED's) and photodetectors
Research program to investigate the fundamental chemistry of technetium ( )
7 editions published between 2000 and 2005 in English and held by 9 WorldCat member libraries worldwide
Technetium (99Tc, half-life = 2.13x105 years,?-emitter) is one of the radionuclides of major concern for nuclear waste disposal. This concern is due to the long half-life of 99Tc, the ease with which pertechnetate, TcO4 -, migrates in the geosphere, difficulties in incorporating Tc into glass waste forms, and the corresponding regulatory considerations. The problem of mobility of pertechnetate in the environment is compounded by the fact that pertechnetate is the thermodynamically stable form of Tc in oxidizing environments. These factors present challenges for the separation and immobilization of Tc. The objective of this research project is to provide new knowledge about the chemical behavior of Tc so that the factors underlying its speciation in nuclear waste and in waste forms can be understood and the problems can be addressed. In particular, the behavior of Tc and Re in glass will be examined since Re is often used as a non-radioactive surrogate to predict the behavior of Tc.(1) In this project, glasses containing both Re and Tc will be prepared, so that the behavior of both metals can be compared under identical conditions
Characterization of Actinides in Simulated Alkaline Tank Waste Sludges and Leachates ( )
5 editions published between 2002 and 2005 in English and held by 8 WorldCat member libraries worldwide
Treatment of underground tanks at Hanford with concentrated alkali to improve removal of waste-limiting components of sludges has proven less efficacious for Al and Cr removal than had been hoped. Hence, more aggressive treatments of sludges, including contact with oxidants targeting Cr(III), have been tested in a limited number of samples and found to enhance Cr removal. Unfortunately, treatments of sludge samples with oxidative alkaline leachates produce conditions under which normally insoluble actinide ions (e.g., Am3+, Pu4+, Np4+) can no longer be reliably assumed to remain in the sludge phase. Few experimental or meaningful theoretical studies of actinide chemistry in strongly alkaline, strongly oxidizing solutions have been completed. Extrapolation of acid phase thermodynamic data to these radically different conditions provides little reliable guidance for predicting actinide speciation in highly salted alkaline solutions. In this project, we are investigating the fundamental chemistry of actinides in sludge simulants and supernatants under representative oxidative leaching conditions. We are also examining the potential impact of acidic leaching with concurrent secondary separations to enhance Al removal. Our objective is to provide adequate insight into actinide behavior under these conditions to enable prudent decision making as tank waste treatment protocols develop. We expect to identify those components of sludges that are likely to be problematic in the application of oxidative leaching protocols
Mechanisms and Kinetics of Organic Aging and Characterization of Intermediates in High-Level Waste ( )
5 editions published between 2002 and 2005 in English and held by 8 WorldCat member libraries worldwide
The objective of this project is to characterize significant chemical degradation pathways of organic chemicals in nuclear waste storage and treatment streams. The effort at Pacific Northwest National Laboratory (PNNL) is closely coordinated with a Notre Dame Radiation Laboratory project (EMSP No. 73832, ''The NOx System in Nuclear Waste'', D. Meisel, Principal Investigator) that focuses on radiolytically induced degradation of organic complexants. An understanding of the chemistry of the organic chemicals present in tank wastes is needed to manage the wastes and related site cleanup activities. The underlying chemistries of high-level waste are (1) the chemistry initiated by radioactive decay and the reactions initiated by heat from radioactive decay and (2) the chemistry resulting from waste management activities (waste transfers between tanks, concentration through evaporators, caustic and other chemical additions). Recognizing that experiments cannot reproduce every conceivable scenario, the PNNL and Notre Dame projects work to develop predictive computational models of these chemistries. Participants in both projects combine experimental observations, electronic structure computations, and theoretical methods developed to achieve this goal. The resulting model will provide an accurate evaluation of the hazardous material generated, including flammable gases, and will support decision-making processes regarding safety, retrieval, and treatment issues. The utility of developing an understanding of tank chemistry has been demonstrated in earlier work. None of the Hanford tanks is currently on a watch list, partially due to predictive understanding of organic aging and flammable gas generation that resulted from previous research. Furthermore, concerns that arise from pretreatment and tank closure issues (e.g., Tc speciation) may be rationalized with the mechanistic knowledge provided by these projects
Radionuclide Sensors for Water Monitoring ( )
5 editions published between 2001 and 2005 in English and held by 8 WorldCat member libraries worldwide
Radionuclide contamination in the soil and groundwater at U.S. Department of Energy (DOE) sites is a severe problem that requires monitoring and remediation. Radionuclide measurement techniques are needed to monitor surface waters, groundwater, and process waters. Typically, water samples are collected and transported to an analytical laboratory, where costly radiochemical analyses are performed. To date, there has been very little development of selective radionuclide sensors for alpha- and beta-emitting radionuclides such as 90Sr, 99Tc, and various actinides of interest. The objective of this project is to investigate novel sensor concepts and materials for sensitive and selective determination of beta- and alpha-emitting radionuclide contaminants in water. To meet the requirements for low-level, isotope-specific detection, the proposed sensors are based on radiometric detection. As a means to address the fundamental challenge of the short ranges of beta and alpha particles in water, our overall approach is based on localization of preconcentration/separation chemistries directly on or within the active area of a radioactivity detector. Automated microfluidics is used for sample manipulation and sensor regeneration or renewal. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for selective preconcentration of radionuclides from environmental samples, new materials that combine chemical selectivity with scintillating properties, new materials that add chemical selectivity to solid-state diode detectors, new preconcentrating column sensors, and improved instrumentation and signal processing for selective radionuclide sensors. New knowledge will provide the basis for designing effective probes and instrumentation for field and in situ measurements
Radiation Effects in Nuclear Waste Materials ( )
5 editions published between 1999 and 2005 in English and held by 8 WorldCat member libraries worldwide
The objective of this multidisciplinary, multi-institutional research effort is to develop a fundamental understanding of radiation effects in glasses and ceramics at the atomic, microscopic, and macroscopic levels. Current research addresses many of the scientific issues identified in the reports of two recent DOE panels (Weber et al. 1997, 1998). The goal of this effort is to provide the underpinning science and models necessary to assess the performance of glasses and ceramics designed for the immobilization and disposal of high-level tank waste, plutonium residues, excess weapons-grade plutonium, and other highly radioactive waste streams. Studies are focused on the effects of ionization and elastic collisions on defect production, defect interactions, diffusion, solid-state phase transformations, and gas accumulation using actinide containing materials, gamma irradiation, ion-beam irradiation, and electron-beam irradiation to simulate the effects of a-decay and b-decay on nuclear waste materials. This program exploits a variety of structural, optical, and spectroscopic probes to characterize the nature and behavior of defects, defect aggregates, and phase transformations. Computer simulation techniques are also used to determine defect production processes, defect energies, and defect/gas diffusion and interactions. A number of irradiation facilities and capabilities are used, including user facilities at other national laboratories, to study the effects of irradiation under different conditions
Overcoming Barriers to the Remediation of Carbon Tetrachloride Through Manipulation of Competing Reaction Mechanisms ( )
4 editions published between 2003 and 2004 in English and held by 7 WorldCat member libraries worldwide
Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl₄) produce chloroform (CHCl₃) as the major product and methylene chloride (CH₂Cl₂) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO⁻). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl₄ that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl₄ through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl₄ degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials
High Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring and Verification Efforts ( )
6 editions published between 1999 and 2004 in English and held by 7 WorldCat member libraries worldwide
Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data can be mapped into the space of the subsurface parameters. We are developing a non-invasive method for accurately imaging the electrical conductivity and dielectric permittivity of the shallow subsurface using the plane wave impedance approach. Electric and magnetic sensors are being tested in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques
Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions ( )
4 editions published between 2001 and 2005 in English and held by 7 WorldCat member libraries worldwide
The principal objective of the project is to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work will include testing the theory of acoustic wave propagation in suspensions and demonstrating the application of the probe by installing it on a flow loop through which a suspension is flowing and determining the particle weight fraction. The signal from the probe must be processed such that the noise arising from the presence of gas bubbles is removed to yield an accurate estimate of the particle weight fraction. Particular attention will be given to testing suspensions with low particle weight fractions since slurries to be transported in nuclear waste processing will have low particle weight fractions. Originally, the probe was to be developed and tested at Syracuse University (SU) then installed and tested at Oak Ridge National Laboratories (ORNL) for surrogate slurries from the Hanford Nuclear site. However, after discussions between SU and ORNL in June 2002 it was agreed that all tests would be conducted at SU
Fission-Product Separation Based on Room-Temperature Ionic Liquids ( )
4 editions published between 2003 and 2006 in English and held by 7 WorldCat member libraries worldwide
The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions
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controlled identity United States. Department of Energy

United States. Dept. of Energy. Environmental Management Science Program
English (142)