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  Partner: UNT Libraries Government Documents Department
 Decade: 1990-1999
Case Studies of integrated hydrogen systems. International Energy Agency Hydrogen Implementing Agreement, Final report for Subtask A of task 11 - Integrated Systems

Case Studies of integrated hydrogen systems. International Energy Agency Hydrogen Implementing Agreement, Final report for Subtask A of task 11 - Integrated Systems

Date: December 31, 1999
Creator: Schucan, T.
Description: Within the framework of the International Energy Agency Hydrogen Implementing Agreement, Task 11 was undertaken to develop tools to assist in the design and evaluation of existing and potential hydrogen demonstration projects. Emphasis was placed on integrated systems, from input energy to hydrogen end use. Included in the PDF document are the Executive Summary of the final report and the various case studies. The activities of task 11 were focused on near- and mid-term applications, with consideration for the transition from fossil-based systems to sustainable hydrogen energy systems. The participating countries were Canada, Italy, Japan, the Netherlands, Spain, Switzerland and the United States. In order for hydrogen to become a competitive energy carrier, experience and operating data need to be generated and collected through demonstration projects. A framework of scientific principles, technical expertise, and analytical evaluation and assessment needed to be developed to aid in the design and optimization of hydrogen demonstration projects to promote implementation. The task participants undertook research within the framework of three highly coordinated subtasks that focused on the collection and critical evaluation of data from existing demonstration projects around the world, the development and testing of computer models of hydrogen components and integrated systems, and ...
Contributing Partner: UNT Libraries Government Documents Department
A Chaotic-Dynamical Conceptual Model to Describe Fluid flow and Contaminant Transport in a Fractured Vadose zone

A Chaotic-Dynamical Conceptual Model to Describe Fluid flow and Contaminant Transport in a Fractured Vadose zone

Date: December 31, 1999
Creator: Faybishenko, Boris; Doughty, Christine; Stoops, Thomas M.; Wood, thomas R. & Wheatcraft, Stephen W.
Description: (1) To determine if and when dynamical chaos theory can be used to investigate infiltration of fluid and contaminant transport in heterogeneous soils and fractured rocks. (2) To introduce a new approach to the multiscale characterization of flow and transport in fractured basalt vadose zones and to develop physically based conceptual models on a hierarchy of scales. The following activities are indicative of the success in meeting the project s objectives: A series of ponded infiltration tests, including (1) small-scale infiltration tests (ponded area 0.5 m2) conducted at the Hell s Half Acre site near Shelley, Idaho, and (2) intermediate-scale infiltration tests (ponded area 56 m2) conducted at the Box Canyon site near Arco, Idaho. Laboratory investigations and modeling of flow in a fractured basalt core. A series of small-scale dripping experiments in fracture models. Evaluation of chaotic behavior of flow in laboratory and field experiments using methods from nonlinear dynamics; Evaluation of the impact these dynamics may have on contaminant transport through heterogeneous fractured rocks and soils, and how it can be used to guide remediation efforts; Development of a conceptual model and mathematical and numerical algorithms for flow and transport that incorporate (1) the spatial variability of heterogeneous ...
Contributing Partner: UNT Libraries Government Documents Department
Characterization of a new family of metal transporters

Characterization of a new family of metal transporters

Date: December 31, 1999
Creator: Guerinot, Mary L. & Dide, David
Description: Metal ions are critical nutrients, yet overaccumulation of these same metals can also be toxic. To maintain appropriate intracellular levels, cells require specific metal uptake systems that are subject to precise homeostatic regulation. The long-range goal of our research is to define the molecular mechanism(s) and regulation of metal ion uptake in eukaryotic cells. Integrating genetic, molecular biological and biochemical approaches, we have examined these processes in the yeast Saccharomyces cerevisiae and the plant Arabidopsis thaliana. Both are proven model systems for studying fundamental cellular processes. Our work has focused on the ZIP family of metal transporters which we identified; this family has representatives in bacteria, fungi,plants and animals. IRT1, one of the founding members of the ZIP family, is an essential cation transporter that is expressed in the epidermal cells of iron deficient plant roots and is responsible for uptake of iron from the soil. We now know that t here are 15 ZIP genes in the Arabidopsis genome which can be divided into four different classes, based on their intron/exon arrangements and the similarities among their encoded gene products. The ZIP family members display different substrate specificities for metals and different tissue distributions in Arabidopsis.Moreover, the family members ...
Contributing Partner: UNT Libraries Government Documents Department
CHEMICAL DECOMPOSITION OF HIGH-LEVEL NUCLEAR WASTE STORAGE/DISPOSAL GLASSES UNDER IRRADIATION

CHEMICAL DECOMPOSITION OF HIGH-LEVEL NUCLEAR WASTE STORAGE/DISPOSAL GLASSES UNDER IRRADIATION

Date: December 31, 1999
Creator: Griscom, Daavid L. & Merzbacher, Celia I.
Description: In the United States alone there are 100 million gallons of high-level nuclear wastes (HLWs) in various chemical forms awaiting eventual disposal in geologic repositories. For safety in handling and transport from their present underground storage tanks to their final burial sites, much of the HLWs are being immobilized by vitrification. A further virtue of HLW vitrification is the fact that the glass may serve as an additional, non-geologic barrier to the dispersal of these radio-toxins into the environment. For this reason, one of the criteria for selecting HLW glass compositions has been chemical durability against attack by ground water. While the effects of radiation on chemical durability have therefore been studied extensively, little consideration has been given to the possibility that self-irradiation of HLW glasses may lead to modes of chemical decomposition which render them unstable even in the absence of exposure to ground water. The worst-case threat would occur if the HLW glasses were to respond to irradiation in ways analogous to rock salt (NaCl). It has long been known that alkali halides irradiated to
Contributing Partner: UNT Libraries Government Documents Department
CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT

CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT

Date: December 31, 1999
Creator: Chuang, Steven S.C.
Description: Photocatalysis could provide a cost-effective route to recycle CO{sub 2} to useful chemicals or fuels. Development of an effective catalyst for the photocatalytic synthesis requires (i) the knowledge of the surface band gap and its relation to the surface structure, (ii) the reactivity of adsorbates and their reaction pathways, and (iii) the ability to manipulate the actives site for adsorption, surface reaction, and electron transfer. The research tasks accomplished during first six months include setting up a photo-catalytic reactor, optical bench, calibration of gas chromatograph, catalyst preparation, and catalyst screening study. Addition of Pt and Cu on TiO{sub 2} was found to increase the activity of TiO{sub 2} catalysts for the synthesis of methanol and methane. The most active catalysts obtained from this study will be used for mechanistic study. The overall goal of this research is to provide a greater predictive capability for the design of visible light-photosynthesis catalysts by a deeper understanding of the reaction kinetics and mechanism as well as by better control of the coordination/chemical environment of active sites.
Contributing Partner: UNT Libraries Government Documents Department
Colloidal Agglomerates in Tank Sludge: Impact on Waste Processing

Colloidal Agglomerates in Tank Sludge: Impact on Waste Processing

Date: December 31, 1999
Creator: Tingey, Joel M.; Berg, John D.; Keefer, K.D.; Lea, A.S.; Rector, D.R.; Virden, J.W. et al.
Description: Disposal of millions of gallons of existing radioactive wastes in underground storage tanks is a major remediation activity for the United States Department of Energy. These wastes include a substantial volume of insoluble sludges consisting of submicron colloidal particles. Processing these sludges under the proposed processing conditions presents unique challenges in retrieval, transport, separation, and solidification of these waste streams. Depending on processing conditions, these colloidal particles can form agglomerated networks having high viscosities that could clog transfer lines or produce high volumes of low-density sediments that interfere with solid-liquid separations. Under different conditions, these particles can be dispersed to form very fine suspended particles that do not settle. Given the wide range of waste chemistries present at Department of Energy sites, it is impractical to measure the properties of all treatment procedures. The underlying principle s of colloid chemistry and physics were studied to provide data that would make it possible to predict and eventually control the physical properties of sludge suspensions and sediment layers in tank wastes and other waste processing streams.
Contributing Partner: UNT Libraries Government Documents Department
Cooled silicon nitride stationary turbine vane risk reduction. Final report

Cooled silicon nitride stationary turbine vane risk reduction. Final report

Date: December 31, 1999
Creator: Holowczak, John
Description: The purpose of this program was to reduce the technical risk factors for demonstration of air cooled silicon nitride turbine vanes. The effort involved vane prototype fabrication efforts at two U.S. based gas turbine grade silicon nitride component manufacturers. The efficacy of the cooling system was analyzed via a thermal time/temperature flow test technique previously at UTRC. By having multiple vendors work on parts fabrication, the chance of program success increased for producing these challenging components. The majority of the effort under this contract focused on developing methods for, and producing, the complex thin walled silicon nitride vanes. Components developed under this program will undergo engine environment testing within N00014-96-2-0014.
Contributing Partner: UNT Libraries Government Documents Department
Determination of Transmutation Effects in Crystalline Waste Forms

Determination of Transmutation Effects in Crystalline Waste Forms

Date: December 31, 1999
Creator: Fortner, Jeffrey A.
Description: The overall goal of this Environmental Management Science Program project was to develop research tools to investigate the effect of transmutation, that is, the radioactive decay of a radioisotope to an isotope of another element, on the stability of a crystalline matrix. This process is an important issue in the assessment of the long-term stability, and hence performance, of a waste form. Most work on radiation effects in waste forms has focused on alpha radiation, which produces more displacements than beta radiation. However, beta radiation results in transmutation, which changes both the valence and the ionic radius of the element undergoing decay. These changes in coordination chemistry may destabilize the waste form and hence permit higher releases of the radionuclide contaminants to the accessible environment. Little is known about the mobility of Cs in pollucite. Only a few studies [1-3] have examined leaching following transmutation or irradiation of pollucite or closely related aluminosilicates. These studies seem to have contradictory results. The results may indicate that prior to radiation-induced amorphization, the accumulated defects may lead to higher leachability of Cs [3], whereas once amorphization occurs, the Cs becomes trapped in the collapsed structure [2]. A more thorough analysis of the effect ...
Contributing Partner: UNT Libraries Government Documents Department
Development of a High Fluence Neutron Source for Nondestructive Characterization of Nuclear Waste

Development of a High Fluence Neutron Source for Nondestructive Characterization of Nuclear Waste

Date: December 31, 1999
Creator: Pickrell, Mark M.
Description: We are addressing the need to measure nuclear wastes, residues, and spent fuel in order to process these for final disposition. For example, TRU wastes destined for the WIPP must satisfy extensive characterization criteria outlined in the Waste Acceptance Criteria, the Quality Assurance Program Plan, and the Performance Demonstration Plan. Similar requirements exist for spent fuel and residues. At present, no nondestructive assay (NDA) instrumentation is capable of satisfying all of the PDP test cycles (particularly for Remote-Handled TRU waste). One of the primary methods for waste assay is by active neutron interrogation. The objective of this project is to improve the capability of all active neutron systems by providing a higher intensity neutron source (by about a factor of 1,000) for essentially the same cost, power, and space requirements as existing systems. This high intensity neutron source is an electrostatically confined (IEC) plasma device. The IEC is a symmetric sphere that was originally developed in the 1960s as a possible fusion reactor. It operates as DT neutron generator. Although it is not likely that this device will scale to fusion reactor levels, previous experiments1 have demonstrated a neutron yield of 2 x 1010 neutrons/second on a table-top device that ...
Contributing Partner: UNT Libraries Government Documents Department
Development of METHANE de-NOX reburning process. Quarterly report, October 1 - December 31, 1999

Development of METHANE de-NOX reburning process. Quarterly report, October 1 - December 31, 1999

Date: December 31, 1999
Creator: unknown
Description: The use of biomass and wood waste solids and sludges as fuel is often hampered by their low heating values and the presence of bound nitrogen that result in inefficient combustion and high NOx emission. Cofiring supplemental fuel through auxiliary burners helps with improving the combustion effectiveness and NOx reduction, but the benefits are limited to the fractional heat input of the auxiliary fuel. Demonstration tests have shown over 60% reduction in NOx, CO and VOC emissions, and a 2% increase in boiler thermal efficiency using only 8 to 13% natural gas.
Contributing Partner: UNT Libraries Government Documents Department
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