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Reduction of pertechnetate by acetohydroxamic acid: Formation of [TcNO(AHA)2(H2O)]+ and implications for the UREX process. (open access)

Reduction of pertechnetate by acetohydroxamic acid: Formation of [TcNO(AHA)2(H2O)]+ and implications for the UREX process.

Reductive nitrosylation and complexation of ammonium pertechnetate by acetohydroxamic acid has been achieved in aqueous nitric and perchloric acid solutions. The kinetics of the reaction depend on the relative concentrations of the reaction components and are accelerated at higher temperatures. The reaction does not occur unless conditions are acidic. Analysis of the x-ray absorption fine structure spectroscopic data is consistent with a pseudo-octahedral geometry with the linear Tc-N-O bond typical of technetium nitrosyl compounds, and electron spin resonance spectroscopy is consistent with a the d{sup 5} Tc(II) nitrosyl complex. The nitrosyl source is generally AHA, but may be augmented by products of reaction with nitric acid. The resulting low-valency trans-aquonitrosyl(diacetohydroxamic)-technetium(II) complex (1) is highly soluble in water, extremely hydrophilic, and is not extracted by tri-n-butylphosphate in a dodecane diluent. Its extraction properties are not pH-dependent; titration studies indicate a single species from pH 4.5 down to -0.6 (calculated). This molecule is resistant to oxidation by H{sub 2}O{sub 2}, even at high pH, and can undergo substitution to form other technetium nitrosyl complexes. The formation of 1 may strongly impact the fate of technetium in the nuclear fuel cycle.
Date: February 26, 2008
Creator: 1Harry Reid Center for Environmental Studies, Nuclear Science and Technology Division, University of Nevada, Las Vegas, Las Vegas, NV, 89154-4006; Gong, Cynthia-May S; Poineau, Frederic; Lukens, Wayne W & Czerwinski, Kenneth R.
System: The UNT Digital Library
Frequency Doubling Broadband Light in Multiple Crystals (open access)

Frequency Doubling Broadband Light in Multiple Crystals

The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.
Date: July 26, 2000
Creator: ALFORD,WILLIAM J. & SMITH,ARLEE V.
System: The UNT Digital Library
Middleware for Astronomical Data Analysis Pipelines (open access)

Middleware for Astronomical Data Analysis Pipelines

In this paper the authors describe the approach to research, develop, and evaluate prototype middleware tools and architectures. The developed tools can be used by scientists to compose astronomical data analysis pipelines easily. They use the SuperMacho data pipelines as example applications to test the framework. they describe their experience from scheduling and running these analysis pipelines on massive parallel processing machines. they use MCR a Linux cluster machine with 1152 nodes and Luster parallel file system as the hardware test-bed to test and enhance the scalability of the tools.
Date: January 26, 2005
Creator: Abdulla, G.; Liu, D.; Garlick, J.; Miller, M.; Nikolaev, S.; Cook, K. et al.
System: The UNT Digital Library
Simulation of the Future LSST Data Pipelines (open access)

Simulation of the Future LSST Data Pipelines

In this paper we describe our approach to build a pipeline simulator for the future Large-scale Synoptic Survey Telescope (LSST). The simulated pipeline will be used to research and evaluate software architectures that are efficient and flexible. It will also be used to define the real-time software and hardware requirements needed to support the anticipated LSST data rates. The LSST data pipeline requirements are still being defined, however, previous surveys can provide a good source for data requirements. Our approach is to use the SuperMacho data pipeline as a prototyping tool to identify a framework for building Modular Data-Centric Pipeline (MDCP) architectures. The prototyping is done in a hierarchical fashion to help capture and define the general data attributes (schema) first. We then model other necessary components based on science and performance requirements. We use identified schemas or data attributes as a way to define a data model for LSST.
Date: July 26, 2004
Creator: Abdulla, Ghaleb M.
System: The UNT Digital Library
Insulated Pressure Vessels for Vehicular Hydrogen Storage: Analysis and Performance Evaluation (open access)

Insulated Pressure Vessels for Vehicular Hydrogen Storage: Analysis and Performance Evaluation

Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (fuel flexibility, lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The work described here is directed at verifying that commercially available pressure vessels can be safely used to store liquid hydrogen. The use of commercially available pressure vessels significantly reduces the cost and complexity of the insulated pressure vessel development effort. This paper describes a series of tests that have been done with aluminum-lined, fiber-wrapped vessels to evaluate the damage caused by low temperature operation. All analysis and experiments to date indicate that no significant damage has resulted. Required future tests are described that will prove that no technical barriers exist to the safe use of aluminum-fiber vessels at cryogenic temperatures. Future activities also include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for obtaining certification for insulated pressure vessels.
Date: June 26, 2001
Creator: Aceves, S. M.; Martinez-Frias, J.; Garcia-Villazana, O. & Espinosa-Loza, F.
System: The UNT Digital Library
A New Dynamical Diffraction-Based Technique of the Residual Stress Measurements in Thin Films (open access)

A New Dynamical Diffraction-Based Technique of the Residual Stress Measurements in Thin Films

The recently discovered dynamical diffraction effect ''neutron camel'' was used for the residual stress measurements in a thick Si(111) crystal coated with a 2000 {angstrom} thick Ni film. The observed asymmetry of the back-face rocking curve corresponds to the bending radius of {approx} 19 km and the tension force applied to the Ni film is {approx} 90 N/m. Relative deformation of the Si crystallographic cells in the vicinity of diffractive surfaces is |{partial_derivative}u{sub z}/{partial_derivative}z| {approx} 1.6 x 10{sup -6}.
Date: July 26, 2001
Creator: Agamalian, M.
System: The UNT Digital Library
High-Level Waste Melter Review (open access)

High-Level Waste Melter Review

The U.S. Department of Energy (DOE) is faced with a massive cleanup task in resolving the legacy of environmental problems from years of manufacturing nuclear weapons. One of the major activities within this task is the treatment and disposal of the extremely large amount of high-level radioactive (HLW) waste stored at the Hanford Site in Richland, Washington. The current planning for the method of choice for accomplishing this task is to vitrify (glassify) this waste for disposal in a geologic repository. This paper describes the results of the DOE-chartered independent review of alternatives for solidification of Hanford HLW that could achieve major cost reductions with reasonable long-term risks, including recommendations on a path forward for advanced melter and waste form material research and development. The potential for improved cost performance was considered to depend largely on increased waste loading (fewer high-level waste canisters for disposal), higher throughput, or decreased vitrification facility size.
Date: February 26, 2002
Creator: Ahearne, J.; Gentilucci, J.; Pye, L. D.; Weber, T.; Woolley, F.; Machara, N. P. et al.
System: The UNT Digital Library
Industrial Complex for Solid Radwaste Management at Chernobyle Nuclear Power Plant (open access)

Industrial Complex for Solid Radwaste Management at Chernobyle Nuclear Power Plant

In the framework of the preparation for the decommissioning of the Chernobyl Nuclear Power Plant (ChNPP) an Industrial Complex for Solid Radwaste Management (ICSRM) will be built under the EC TACIS Program in the vicinity of ChNPP. The paper will present the proposed concepts and their integration into existing buildings and installations. Further, the paper will consider the safety cases, as well as the integration of Western and Ukrainian Organizations into a cohesive project team and the requirement to guarantee the fulfillment of both Western standards and Ukrainian regulations and licensing requirements. The paper will provide information on the status of the interim design and the effects of value engineering on the output of basic design phase. The paper therefor summarizes the design results of the involved design engineers of the Design and Process Providers BNFL (LOT 1), RWE NUKEM GmbH (LOT 2 and General) and INITEC (LOT 3).
Date: February 26, 2002
Creator: Ahner, S. & Fomin, V. V.
System: The UNT Digital Library
Energy effects of heat-island reduction strategies in Toronto,Canada (open access)

Energy effects of heat-island reduction strategies in Toronto,Canada

The effect of heat-island reduction (HIR) strategies on annual energy savings and peak-power avoidance of the building sector of the Greater Toronto Area is calculated, using an hourly building energy simulation model. Results show that ratepayers could realize potential annual energy savings of over $11M from the effects of HIR strategies. The residential sector accounts for over half (59%) of the total savings, offices 13% and retail stores 28%. Savings from cool roofs are about 20%, shade trees 30%, wind shielding of trees 37%, and ambient cooling by trees and reflective surfaces 12%. These results are preliminary and highly sensitive to the relative price of gas and electricity. Potential annual electricity savings are estimated at about 150GWh and potential peak-power avoidance at 250MW.
Date: August 26, 2003
Creator: Akbari, Hashem & Konopacki, Steven
System: The UNT Digital Library
Structure of the Lithosphere and Upper Mantle Across the Arabian Peninsula (open access)

Structure of the Lithosphere and Upper Mantle Across the Arabian Peninsula

None
Date: August 26, 2008
Creator: Al-Amri, A.; Rodgers, A.; Hansen, S.; Nyblade, A.; Park, Y. & Tkalcic, H.
System: The UNT Digital Library
Evaporative Evolution of Brines from Synthetic Topoah Spring Tuff Pore Water, Yucca Mountain, NV (open access)

Evaporative Evolution of Brines from Synthetic Topoah Spring Tuff Pore Water, Yucca Mountain, NV

We are investigating the evaporation of pore water representative of the designated high-level-nuclear-waste repository at Yucca Mountain, NV to predict the range of brine compositions that may contact waste containers. These brines could form potentially corrosive thin films on the containers and impact their long-term integrity. Here we report the geochemistry of a relatively complex synthetic Topopah Spring Tuff pore water that was progressively evaporated in a series of experiments. The experiments were conducted in a closed vessel, heated to 95 C, and purged with atmospheric CO{sub 2}. Aqueous samples of the evaporating solution were taken and analyzed to determine the evolving water chemistry, and the final solid precipitate was analyzed by X-ray diffraction. The synthetic Topopah Spring Tuff water evolved towards a complex brine that contains about 3 mol% SO{sub 4}, and 2 mol% Ca, 3 mol% K, 5 mol% NO{sub 3}, 40 mol% Cl, and 47 mol% Na. Trends in the solution data and identification of CaSO{sub 4} solids (anhydrite and bassanite) suggest that fluorite, carbonate, sulfate, and Mg-silicate precipitation minimize the corrosion potential of ''sulfate type pore water'' by removing F, Ca, and Mg during the early stages of evaporation.
Date: November 26, 2002
Creator: Alai, M & Carroll, S
System: The UNT Digital Library
GUT implications from neutrino mass (open access)

GUT implications from neutrino mass

An overview is given of the experimental neutrino mixing results and types of neutrino models proposed, with special attention to the general features of various GUT models involving intra-family symmetries and horizontal flavor symmetries. Many of the features are then illustrated by a specific SO (10) SUSY GUT model formulated by S.M. Barr and the author which can explain all four types of solar neutrino mixing solutions by various choices of the right-handed Majorana mass matrix. The quantitative nature of the model's large mixing angle solution is used to compare the reaches of a neutrino super beam and a neutrino factory for determining the small U{sub e3} mixing matrix element.
Date: June 26, 2001
Creator: Albright, Carl H.
System: The UNT Digital Library
Undulator-Based Production of Polarized Positrons (open access)

Undulator-Based Production of Polarized Positrons

None
Date: May 26, 2009
Creator: Alexander, Gideon; Barley, John; Batygin, Yuri; Berridge, Steven; Bharadwaj, Vinod; Bower, Gary et al.
System: The UNT Digital Library
Non-Poisson Dichotomous Noise: Higher-Order Correlation Functions and Aging (open access)

Non-Poisson Dichotomous Noise: Higher-Order Correlation Functions and Aging

This article discusses non-Poisson dichotomous noise and higher-order correlation functions and aging.
Date: October 26, 2004
Creator: Allegrini, Paolo; Grigolini, Paolo; Palatella, Luigi & West, Bruce J.
System: The UNT Digital Library
Recommendation for Supplemental Technologies for Hanford River Protection Project Potential Mission Acceleration (RPP-11838) (open access)

Recommendation for Supplemental Technologies for Hanford River Protection Project Potential Mission Acceleration (RPP-11838)

In May of 2002, the River Protection Project at Hanford proposed as part of the accelerated cleanup for the entire Hanford Site to ''accelerate waste stabilization by developing and deploying alternative treatment and immobilization solutions that are aligned with the waste characteristics to add assurance that overall waste treatment/immobilization will be completed 20 or more years sooner.'' This paper addresses one of these elements: development of recommendations for the supplemental technologies that have the greatest potential to supplement the River Protection Project's new Waste Treatment Plant throughput and achieve completion of waste processing by 2028. Low-activity waste treatment in the Waste Treatment Plant needs either to be enhanced or supplemented to enable the full amount of low-activity feed in the single-shell and double-shell tanks to be processed by 2028. The supplemental technologies are considered for low-activity waste feed that represents the maximum effectiveness of treatment compared with Waste Treatment Plant processing. During the Spring of 2002, over two dozen candidate technologies were assessed by staff from the U.S Department of Energy (DOE) Headquarters, Hanford Office of River Protection, representatives from the Washington State Department of Ecology and Region 10 of the Environmental Protection Agency, staff from many national laboratories, as …
Date: February 26, 2003
Creator: Allen, D. I.; Raymond, R. E.; Group, CH2M Hill Hanford; Brouns, T. M.; Choho, A. F.; Corporation, Numatec Hanford et al.
System: The UNT Digital Library
Mechanical design and analysis of the Fermilab 11 T Nb{sub 3}Sn dipole model (open access)

Mechanical design and analysis of the Fermilab 11 T Nb{sub 3}Sn dipole model

The goal of the Fermilab High Field Magnet (HFM) R and D project is to explore various designs and production technology of a high-field, low-cost Nb{sub 3}Sn accelerator magnet suitable for a future Very Large Hadron Collider (VLHC). The model under fabrication consists of two-layer shell-type coil with 43.5 mm aperture and cold iron yoke. Fermilab concept of magnet design and fabrication technology involves some specific features such as curing of half-coil with ceramic binder/matrix before reaction, and then simultaneous reaction and impregnation of both half-coils to get a coil pipe structure. The coil pipe is mechanically supported by the vertically-split iron yoke locked by two aluminum clamps and a thick stainless steel skin. 2D finite element analysis has been performed to study and optimize the prestress in the coil and in the structural elements at room temperature and at 4.2 K. Model description, material properties and the results of mechanical analysis are reported in this paper.
Date: January 26, 2000
Creator: Ambrosio, G.
System: The UNT Digital Library
Study of the react and wind technique for a Nb{sub 3}Sn common coil dipole (open access)

Study of the react and wind technique for a Nb{sub 3}Sn common coil dipole

Fermilab, in collaboration with LBNL, is exploring the use of the react and wind technique for a common coil dipole with a Nb{sub 3}Sn Rutherford cable. An R and D program on conductor design and magnet technology was begun aiming at an 11 T, 2 layer, 30 mm aperture design operating at 4.5 K. The goal is to explore the feasibility of the react and wind technique for flat coils with a minimum bending radius of 90 mm. In order to improve the understanding of the I{sub c} degradation caused by bending after reaction this effect will be studied on both strands and cables. In this paper, the authors present two techniques to measure the critical current degradation due to bending, both in wires and cables, using standard test facilities. Together with the description of the program they show the results of the first measurements on strands and the layout of the cables that are being produced.
Date: January 26, 2000
Creator: Ambrosio, G.
System: The UNT Digital Library
Assessing the Prospects for Achieving Double-Shell Ignition on the National Ignition Facility Using Vacuum Hohlraums (open access)

Assessing the Prospects for Achieving Double-Shell Ignition on the National Ignition Facility Using Vacuum Hohlraums

The goal of demonstrating ignition on the National Ignition Facility (NIF) has motivated a revisit of double-shell (DS) targets as a complementary path to the cryogenic baseline approach. Expected benefits of DS ignition targets include non-cryogenic deuterium-tritium (DT) fuel preparation, minimal hohlraum-plasma mediated laser backscatter, low threshold ignition temperatures ({approx} 4 keV) for relaxed hohlraum x-ray flux asymmetry tolerances, and minimal (two-) shock timing requirements. On the other hand, DS ignition presents several formidable challenges, encompassing room-temperature containment of high-pressure DT ({approx} 790 atm) in the inner shell, strict concentricity requirements on the two shells (< 3 {micro}m), development of nano-porous (<100 nm) low-density (<100 mg/cc) metallic foams for structural support of the inner shell and hydrodynamic instability mitigation, and effective control of hydrodynamic instabilities on the high-Atwood number interface between the DT fuel and the high-Z inner shell. Recent progress in DS ignition designs and required materials-science advances at the nanoscale are described herein. Two new ignition designs that use rugby-shaped vacuum hohlraums are presented which utilize either 1 MJ or 2 MJ of laser energy at 3{omega}. The capability of the NIF to generate the requested reverse-ramp pulse shape for DS ignition is expected to be comparable to …
Date: October 26, 2006
Creator: Amendt, P.; Cerjan, C.; Hamza, A.; Hinkel, D.; Milovich, J. L. & Robey, H. F.
System: The UNT Digital Library
Technical Evaluations of Proposed Remote-Handled Transuranic Waste Characterization Requirements at WIPP (open access)

Technical Evaluations of Proposed Remote-Handled Transuranic Waste Characterization Requirements at WIPP

Characterization, packaging, transport, handling and disposal of remotely handled transuranic (RH TRU) waste at WIPP will be different than similar operations with contact handled transuranic (CH TRU) waste. This paper presents results of technical evaluations associated with the planned disposal of remotely handled transuranic waste at the Waste Isolation Pilot Plant (WIPP).
Date: February 26, 2002
Creator: Anastas, G. & Channell, J. K.
System: The UNT Digital Library
Imaging the separation of cathodic arc plasma and macroparticles in curved magnetic filters (open access)

Imaging the separation of cathodic arc plasma and macroparticles in curved magnetic filters

None
Date: September 26, 2001
Creator: Anders, Andre
System: The UNT Digital Library
Staggered grid lagrangian method with local structured adaptive mesh refinement for modeling shock hydrodynamics (open access)

Staggered grid lagrangian method with local structured adaptive mesh refinement for modeling shock hydrodynamics

A new method for the solution of the unsteady Euler equations has been developed. The method combines staggered grid Lagrangian techniques with structured local adaptive mesh refinement (AMR). This method is a precursor to a more general adaptive arbitrary Lagrangian Eulerian (ALE-AMR) algorithm under development, which will facilitate the solution of problems currently at and beyond the boundary of soluble problems by traditional ALE methods by focusing computational resources where they are required. Many of the core issues involved in the development of the ALE-AMR method hinge upon the integration of AMR with a Lagrange step, which is the focus of the work described here. The novel components of the method are mainly driven by the need to reconcile traditional AMR techniques, which are typically employed on stationary meshes with cell-centered quantities, with the staggered grids and grid motion employed by Lagrangian methods. These new algorithmic components are first developed in one dimension and are then generalized to two dimensions. Solutions of several model problems involving shock hydrodynamics are presented and discussed.
Date: September 26, 2000
Creator: Anderson, R W; Pember, R B & Elliot, N S
System: The UNT Digital Library
Waste Minimization Policy at the Romanian Nuclear Power Plant (open access)

Waste Minimization Policy at the Romanian Nuclear Power Plant

The radioactive waste management system at Cernavoda Nuclear Power Plant (NPP) in Romania was designed to maintain acceptable levels of safety for workers and to protect human health and the environment from exposure to unacceptable levels of radiation. In accordance with terminology of the International Atomic Energy Agency (IAEA), this system consists of the ''pretreatment'' of solid and organic liquid radioactive waste, which may include part or all of the following activities: collection, handling, volume reduction (by an in-drum compactor, if appropriate), and storage. Gaseous and aqueous liquid wastes are managed according to the ''dilute and discharge'' strategy. Taking into account the fact that treatment/conditioning and disposal technologies are still not established, waste minimization at the source is a priority environmental management objective, while waste minimization at the disposal stage is presently just a theoretical requirement for future adopted technologies . The necessary operational and maintenance procedures are in place at Cernavoda to minimize the production and contamination of waste. Administrative and technical measures are established to minimize waste volumes. Thus, an annual environmental target of a maximum 30 m3 of radioactive waste volume arising from operation and maintenance has been established. Within the first five years of operations at …
Date: February 26, 2002
Creator: Andrei, V. & Daian, I.
System: The UNT Digital Library
Saltcake Dissolution Studies in Single-Shell Tank Retrieval (open access)

Saltcake Dissolution Studies in Single-Shell Tank Retrieval

Results of column dissolution experiments designed to evaluate the physical and chemical processes inherent to saltcake dissolution are presented along with model chemical equilibrium calculations. Two different compositions representing saltcakes in Hanford tanks were characterized, and porosities and permeabilities for a third composition based upon the saltcake waste in Tank 41H at the Savannah River Site (SRS) were also evaluated. Whereas the surrogates are all chemically similar, the presence of high phosphate loadings for the Hanford (HNF) simulants was noted as significantly affecting draining. The permeability was higher for the SRS saltcake, and the sodium nitrate loading in this saltcake was roughly 80% by weight compared to less than 60% by weight for the HNF compositions. Average values of the permeability and porosity were reduced for the surrogates based on Hanford Tanks S-112 and S-101. Here a secondary layer formed above the saltcake bed and was found to contain a large amount of gibbsite, Al(OH)3. Experiments with 3 molal (m) NaOH as a diluent, compared to water, did not result in additional layer formation that has been attributed to a change in local pH thereby altering the solid liquid equilibrium. Chemical analysis of the two HNF saltcakes indicated solids re-precipitation …
Date: February 26, 2003
Creator: Antonyraj, A.; Durve, T.; Toghiani, R. K.; Lindner, J. S. & Hunt, R.
System: The UNT Digital Library
Virtual data in CMS production (open access)

Virtual data in CMS production

Initial applications of the GriPhyN Chimera Virtual Data System have been performed within the context of CMS Production of Monte Carlo Simulated Data. The GriPhyN Chimera system consists of four primary components: (1) a Virtual Data Language, which is used to describe virtual data products, (2) a Virtual Data Catalog, which is used to store virtual data entries, (3) an Abstract Planner, which resolves all dependencies of a particular virtual data product and forms a location and existence independent plan, (4) a Concrete Planner, which maps an abstract, logical plan onto concrete, physical grid resources accounting for staging in/out files and publishing results to a replica location service. A CMS Workflow Planner, MCRunJob, is used to generate virtual data products using the Virtual Data Language. Subsequently, a prototype workflow manager, known as WorkRunner, is used to schedule the instantiation of virtual data products across a grid.
Date: August 26, 2004
Creator: Arbree, A.
System: The UNT Digital Library