Effects of Global Boundary and Local Collisionality on Magnetic Reconnection in a Laboratory Plasma (open access)

Effects of Global Boundary and Local Collisionality on Magnetic Reconnection in a Laboratory Plasma

The magnetic reconnection process is studied in a wide range of operating conditions in the well-controlled Magnetic Reconnection Experiment. The reconnection rate is observed to be a function of both global (i.e., system size) and local (collisionality) plasma parameters. When only local collisionality is lowered, the current sheet is shortened while effective resistivity is enhanced, both accelerating reconnection rates. At a fixed collisionality, the current sheet length increases with system size, resulting in the reduction of the reconnection rate. These results quantitatively agree with a generalized Sweet-Parker analysis.
Date: July 24, 2007
Creator: A. Kuritsyn, H. Ji, S.P. Gerhardt, Y. Ren, and M. Yamada
Object Type: Report
System: The UNT Digital Library
Pressure-induced Breaking of Equilibrium Flux Surfaces in the W7AS Stellarator (open access)

Pressure-induced Breaking of Equilibrium Flux Surfaces in the W7AS Stellarator

Calculations are presented for two shots in the W7AS stellarator which differ only in the magnitude of the current in the divertor control coil, but have very different values of experimentally attainable β (<β> ≈ 2.7% versus <β> ≈ 1.8%). Equilibrium calculations find that a region of chaotic magnetic field line trajectories fills approximately the outer 1/3 of the cross-section in each of these configurations. The field lines in the stochastic region are calculated to behave as if the flux surfaces are broken only locally near the outer midplane and are preserved elsewhere. The calculated magnetic field line diffusion coefficients in the stochastic regions for the two shots are consistent with the observed differences in the attainable β, and are also consistent with the differences in the reconstructed pressure profiles.
Date: April 24, 2007
Creator: A. Reiman, M.C. Zarnstorff, D. Monticello, A. Weller, J. Geiger, and the W7-AS Team
Object Type: Article
System: The UNT Digital Library
NUCLEAR WASTE GLASSES CONTINUOUS MELTING AND BULK VITRIFICAITON (open access)

NUCLEAR WASTE GLASSES CONTINUOUS MELTING AND BULK VITRIFICAITON

This contribution addresses various aspects of nuclear waste vitrification. Nuclear wastes have a variety of components and composition ranges. For each waste composition, the glass must be formulated to possess acceptable processing and product behavior defined in terms of physical and chemical properties that guarantee the glass can be easily made and resist environmental degradation. Glass formulation is facilitated by developing property-composition models, and the strategy of model development and application is reviewed. However, the large variability of waste compositions presents numerous additional challenges: insoluble solids and molten salts may segregate; foam may hinder heat transfer and slow down the process; molten salts may accumulate in container refractory walls; the glass on cooling may precipitate crystalline phases. These problems need targeted exploratory research. Examples of specific problems and their possible solutions are discussed.
Date: March 24, 2008
Creator: AA, KRUGER & PR, HRMA
Object Type: Article
System: The UNT Digital Library
Sorption of Cesium From Aqueous Waste Solution on SuperLig 644 Resin (open access)

Sorption of Cesium From Aqueous Waste Solution on SuperLig 644 Resin

The removal of cesium from aqueous waste solution was investigated in a column setup using SuperLig(R) 644 resin. The resin was significantly coarser in size than those used in previous studies because of hydraulic problems encountered during pilot-scale tests. The bed volume (BV = 140) at the onset of breakthrough surpassed the design requirement of 100 BV at 50 percent breakthrough. The percent of cesium removed by the resin at the onset of breakthrough was 99.96. The elution of cesium with 0.5 M HNO3 was satisfactory with a peak BV of 2.5. The elution BV for C/Co = 0.01 was 10, which is less than the target of 15 BV. The percent of sorbed cesium eluted from the resin was 99.88 percent. In addition, the BV of the various solutions used for the supporting process steps (feed displacement, post-feed displacement rinse, post-elution rinse, and regeneration) of the cesium ion exchange system was sufficient.
Date: August 24, 2004
Creator: ADU-WUSU, KOFI
Object Type: Article
System: The UNT Digital Library
HANFORD REGULATORY EXPERIENCE REGULATION AT HANFORD A CASE STUDY (open access)

HANFORD REGULATORY EXPERIENCE REGULATION AT HANFORD A CASE STUDY

Hanford has played a pivotal role in the United States' defense for more than 60 years, beginning with the Manhattan Project in the 1940s. During its history, the Hanford Site has had nine reactors producing plutonium for the United States' nuclear weapons program. All the reactors were located next to the Columbia River and all had associated low-level radioactive and hazardous waste releases. Site cleanup, which formally began in 1989 with the signing of the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement, involves more than 1,600 waste sites and burial grounds, and the demolition of more than 1,500buildings and structures, Cleanup is scheduled to be complete by 2035. Regulatory oversight of the cleanup is being performed by the U.S. Environmental Protection Agency (EPA) and the Washington State Department of Ecology(Ecology) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Revised Code of Washington, 'Hazardous Waste Management.' Cleanup of the waste sites and demolition of the many buildings and structures generates large volumes of contaminated soil, equipment, demolition debris, and other wastes that must be disposed of in a secure manner to prevent further environmental degradation. From a risk perspective, it is …
Date: September 24, 2007
Creator: AR, HAWKINS
Object Type: Article
System: The UNT Digital Library
Evaluation of the Cask Transportation Facility Modifications (CTFM) compliance to DOE order 6430.1A Project A.5 and A.6 (open access)

Evaluation of the Cask Transportation Facility Modifications (CTFM) compliance to DOE order 6430.1A Project A.5 and A.6

This report was prepared to evaluate the compliance of CTFM to DOE Order 6430.1A. This document presents the results of an evaluation that was performed to assess compliance of the K West (KW) Cask Transportation Facility Modifications (CTFM) designs against applicable requirements of Department of Energy (DOE) Order 6430.1 A, General Design Criteria. This evaluation was grouped under two categories described as Cask Loadout System (CLS) and Cranes/Other Modifications.
Date: April 24, 2000
Creator: ARD, K.E.
Object Type: Report
System: The UNT Digital Library
Heavy-Duty Emissions Control: Plasma-Facilitated vs Reformer-Assisted Lean NOx Catalysis (open access)

Heavy-Duty Emissions Control: Plasma-Facilitated vs Reformer-Assisted Lean NOx Catalysis

Progress has been made in the control of combustion processes to limit the formation of environmentally harmful species, but lean burn vehicles, such as those powered by diesel engines used for the majority of commercial trucking and off-road applications, remain a major source of nitrogen oxides (NOx) and particulate matter (PM) emissions. Tighter control of the combustion process coupled with exhaust gas recirculation has brought emissions in line with 2004 targets worldwide. Additional modifications to the engine control system, somewhat limited NOx control, and PM filters will likely allow the 2007 limits to be met for the on-highway regulations for heavy-duty engines in the United States. Concern arises when the NOx emission limit of 0.2 g/bhphr set for the year 2010 is considered.
Date: August 24, 2003
Creator: Aardahl, C. L.; Rozmiarek, R. T.; Rappe, K. G.; Mendoza, D. P. & Park, P. W.
Object Type: Article
System: The UNT Digital Library
Energy Policy Act of 2005, P.L. 109-58: Electricity Provisions (open access)

Energy Policy Act of 2005, P.L. 109-58: Electricity Provisions

None
Date: January 24, 2006
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Micro-Grooving and Micro-Threading Tools for Fabricating Curvilinear Features (open access)

Micro-Grooving and Micro-Threading Tools for Fabricating Curvilinear Features

This paper presents techniques for fabricating microscopic, curvilinear features in a variety of workpiece materials. Micro-grooving and micro-threading tools having cutting widths as small as 13 {micro}m are made by focused ion beam sputtering and used for ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide to create a number of critically aligned facets. Sputtering produces rake facets of desired angle and cutting edges having radii of curvature equal to 0.4 {micro}m. Clearance for minimizing frictional drag of a tool results from a particular ion beam/target geometry that accounts for the sputter yield dependence on incidence angle. It is believed that geometrically specific cutting tools of this dimension have not been made previously. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close match between tool width and feature size. Microtools are used to machine 13 {micro}m wide, 4 {micro}m deep, helical grooves in polymethyl methacrylate and 6061 Al cylindrical workplaces. Micro-grooving tools are also used to fabricate sinusoidal cross-section features in planar metal samples.
Date: July 24, 2000
Creator: Adams, David P.; Vasile, Michael J. & Krishnan, A. S. M.
Object Type: Article
System: The UNT Digital Library
Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors (open access)

Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors

The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively …
Date: November 24, 2004
Creator: Adams, Gregory P.
Object Type: Report
System: The UNT Digital Library
DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION (open access)

DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION

DWPF is considering replacing irregularly shaped glass frit with spherical glass beads in the Slurry Mix Evaporator (SME) process to decrease the yield stress of the melter feed (a non-Newtonian Bingham Plastic). Pilot-scale testing was conducted on spherical glass beads and glass frit to determine how well the glass beads would transfer when compared to the glass frit. Process Engineering Development designed and constructed the test apparatus to aid in the understanding and impacts that spherical glass beads may have on the existing DWPF Frit Transfer System. Testing was conducted to determine if the lines would plug with the glass beads and the glass frit slurry and what is required to unplug the lines. The flow loop consisted of vertical and horizontal runs of clear PVC piping, similar in geometry to the existing system. Two different batches of glass slurry were tested: a batch of 50 wt% spherical glass beads and a batch of 50 wt% glass frit in process water. No chemicals such as formic acid was used in slurry, only water and glass formers. The glass beads used for this testing were commercially available borosilicate glass of mesh size -100+200. The glass frit was Frit 418 obtained from …
Date: November 24, 2008
Creator: Adamson, D & Bradley Pickenheim, B
Object Type: Report
System: The UNT Digital Library
A Binary Segmentation Approach for Boxing Ribosome Particles in Cryo EM Micrographs (open access)

A Binary Segmentation Approach for Boxing Ribosome Particles in Cryo EM Micrographs

Three-dimensional reconstruction of ribosome particles from electron micrographs requires selection of many single-particle images. Roughly 100,000 particles are required to achieve approximately 10 angstrom resolution. Manual selection of particles, by visual observation of the micrographs on a computer screen, is recognized as a bottleneck in automated single particle reconstruction. This paper describes an efficient approach for automated boxing of ribosome particles in micrographs. Use of a fast, anisotropic non-linear reaction-diffusion method to pre-process micrographs and rank-leveling to enhance the contrast between particles and the background, followed by binary and morphological segmentation constitute the core of this technique. Modifying the shape of the particles to facilitate segmentation of individual particles within clusters and boxing the isolated particles is successfully attempted. Tests on a limited number of micrographs have shown that over 80 percent success is achieved in automatic particle picking.
Date: June 24, 2003
Creator: Adiga, Umesh P. S.; Malladi, Ravi; Baxter, William & Glaeser, Robert M.
Object Type: Article
System: The UNT Digital Library
Underground Corrosion of Activated Metals in an Arid Vadose Zone Environment (open access)

Underground Corrosion of Activated Metals in an Arid Vadose Zone Environment

The subsurface radioactive disposal site located at the Idaho National Engineering and Environmental Laboratory contains neutron-activated metals from nonfuel nuclear-reactor- core components. A long-term corrosion test is being conducted to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements in an arid vadose zone environment. The tests use nonradioactive metal coupons representing the prominent neutron-activated material buried at the disposal location, namely, Type 304L stainless steel, Type 315L stainless steel, nickel-chromium alloy (UNS NO7718), beryllium, aluminum 6061-T6, and a zirconium alloy, (UNS R60804). In addition, carbon steel (the material presently used in the cask disposal liners and other disposal containers) and a duplex stainless steel (UNS S32550) (the proposed material for the high- integrity disposal containers) are also included in the test program. This paper briefly describes the test program and presents the early corrosion rate results after 1 year and 3 years of underground exposure.
Date: October 24, 2001
Creator: Adler Flitton, M. K.; Mizia, R. E. & Bishop, C. W.
Object Type: Article
System: The UNT Digital Library
The Ghanaian Approach to the Development of an Effective Waste Management Regime (open access)

The Ghanaian Approach to the Development of an Effective Waste Management Regime

In Ghana, radioactive waste is generated mainly from spent sealed sources, various nuclear applications--diagnostic and therapeutic procedures in medicine and measurement and processing techniques in industry. The radionuclide composition in the waste arising from industry, research and teaching includes 14C, 137Cs, 60Co, 241Am, 3H, 32P, 125I, 192Ir, 131I, 99m Tc, 35S and 90Sr. Ghana is strengthening its radioactive waste management infrastructure, which include the development of a legal framework by providing laws, regulations and guidelines and allocating responsibilities of waste generators, the National Radioactive Waste Management Centre (NRWMC), and the Radiation Protection Board (RPB). The radioactive waste management regulations which is in it's final stage of promulgation set up the basic technical and organizational requirements to be complied with by waste generators and operators of waste management facilities and make provisions for penalties for non-compliance with the regulations. With the installation of a 30 kW Research Reactor for neutron activation analysis, 185 TBq 60Co facility for the treatment of cancer at the Korle-bu teaching hospital, 1850 TBq 60Co facility for irradiation of medical and agricultural products and 192Ir sources for industrial radiography, radioactive waste is expected to increase in the near future. At present, waste management is limited exclusively to …
Date: February 24, 2003
Creator: Adu, P. S.; Gbadago, J. K. & Glover, E. T.
Object Type: Article
System: The UNT Digital Library
B-factory signals for a warped extra dimension (open access)

B-factory signals for a warped extra dimension

We study predictions for B-physics in a class of models, recently introduced, with a non-supersymmetric warped extra dimension. In these models few ({approx} 3) TeV Kaluza-Klein masses are consistent with electroweak data due to bulk custodial symmetry. Furthermore, there is an analog of GIM mechanism which is violated by the heavy top quark (just as in SM) leading to striking signals at B-factories: (1) New Physics (NP) contributions to {Delta}F = 2 transitions are comparable to SM. This implies that, within this NP framework, the success of the SM unitarity triangle fit is a ''coincidence''. Thus, clean extractions of unitarity angles via e.g. B {yields} {pi}{pi}, {rho}{pi}, {rho}{rho}, DK are likely to be affected, in addition to O(1) deviation from SM prediction in Bs mixing. (2) O(1) deviation from SM predictions for B {yields} X{sub s}{ell}{sup +}{ell}{sup -} in rate as well as in forward-backward and direct CP asymmetry. (3) Large mixing-induced CP asymmetry in radiative B decays, wherein the SM unambiguously predicts very small asymmetries. Also, with KK masses 3 TeV or less, and with anarchic Yukawa masses, contributions to electric dipole moments of the neutron are roughly 20 times larger than the current experimental bound so that this …
Date: August 24, 2004
Creator: Agashe, Kaustubh; Perez, Gilad & Soni, Amarjit
Object Type: Article
System: The UNT Digital Library
Waste Form and Indrift Colloids-Associated Radionuclide Concentrations: Abstraction and Summary (open access)

Waste Form and Indrift Colloids-Associated Radionuclide Concentrations: Abstraction and Summary

This Model Report describes the analysis and abstractions of the colloids process model for the waste form and engineered barrier system components of the total system performance assessment calculations to be performed with the Total System Performance Assessment-License Application model. Included in this report is a description of (1) the types and concentrations of colloids that could be generated in the waste package from degradation of waste forms and the corrosion of the waste package materials, (2) types and concentrations of colloids produced from the steel components of the repository and their potential role in radionuclide transport, and (3) types and concentrations of colloids present in natural waters in the vicinity of Yucca Mountain. Additionally, attachment/detachment characteristics and mechanisms of colloids anticipated in the repository are addressed and discussed. The abstraction of the process model is intended to capture the most important characteristics of radionuclide-colloid behavior for use in predicting the potential impact of colloid-facilitated radionuclide transport on repository performance.
Date: June 24, 2003
Creator: Aguilar, R.
Object Type: Report
System: The UNT Digital Library
European Trade Retaliation: The FSC-ETI Case (open access)

European Trade Retaliation: The FSC-ETI Case

None
Date: January 24, 2006
Creator: Aheam, Raymond J.
Object Type: Report
System: The UNT Digital Library
Globalization, Worker Insecurity, and Policy Approaches (open access)

Globalization, Worker Insecurity, and Policy Approaches

None
Date: July 24, 2007
Creator: Aheam, Raymond J.
Object Type: Report
System: The UNT Digital Library
Trade and the Americas (open access)

Trade and the Americas

None
Date: May 24, 2002
Creator: Ahearn, Raymond J.
Object Type: Report
System: The UNT Digital Library
Transatlantic Regulatory Cooperation: Background and Analysis (open access)

Transatlantic Regulatory Cooperation: Background and Analysis

This report is intended to serve as an introduction and primer on a complicated, broad, and often highly technical set of issues.
Date: August 24, 2009
Creator: Ahearn, Raymond J.
Object Type: Report
System: The UNT Digital Library
U.S.-European Union Trade Relations: Issues and Policy Challenges (open access)

U.S.-European Union Trade Relations: Issues and Policy Challenges

None
Date: October 24, 2002
Creator: Ahearn, Raymond J.
Object Type: Report
System: The UNT Digital Library
Western Hemisphere Trade Developments (open access)

Western Hemisphere Trade Developments

None
Date: June 24, 2002
Creator: Ahearn, Raymond J.
Object Type: Report
System: The UNT Digital Library
Developing high brightness and high current beams for HIF injectors (open access)

Developing high brightness and high current beams for HIF injectors

The US Heavy Ion Fusion Virtual National Laboratory is continuing research into ion sources and injectors that simultaneously provide high current (0.5-1.0 Amps) and high brightness (normalized emittance better than 1.0 {pi}-mm-mr). The central issue of focus is whether to continue pursuing the traditional approach of large surface ionization sources or to adopt a multiaperture approach that transports many smaller ''beamlets'' separately at low energies before allowing them to merge. For the large surface source concept, the recent commissioning of the 2-MeV injector for the High Current eXperiment has increased our understanding of the beam quality limitations for these sources. We have also improved our techniques for fabricating large diameter aluminosilicate sources to improve lifetime and emission uniformity. For the multiaperture approach, we are continuing to study the feasibility of small surface sources and a RF induced plasma source in preparation for beamlet merging experiments, while continuing to run computer simulations for better understanding of this alternate concept. Experiments into both architectures will be performed on a newly commissioned ion source test stand at LLNL called STS-500. This stand test provides a platform for testing a variety of ion sources and accelerating structures with 500 kV, 17-microsecond pulses. Recent progress …
Date: May 24, 2002
Creator: Ahle, Larry; Grote, Dave & Kwan, Joe
Object Type: Article
System: The UNT Digital Library
Neutrino Observations From the Sudbury Neutrino Observatory (open access)

Neutrino Observations From the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) is a water imaging Cherenkov detector. Its usage of 1000 metric tons of D{sub 2}O as target allows the SNO detector to make a solar-model independent test of the neutrino oscillation hypothesis by simultaneously measuring the solar {nu}{sub e} flux and the total flux of all active neutrino species. Solar neutrinos from the decay of {sup 8}B have been detected at SNO by the charged-current (CC) interaction on the deuteron and by the elastic scattering (ES) of electrons. While the CC reaction is sensitive exclusively to {nu}{sub e}, the ES reaction also has a small sensitivity to {nu}{sub {mu}} and {nu}{sub {tau}}. In this paper, recent solar neutrino results from the SNO experiment are presented. It is demonstrated that the solar flux from {sup 8}B decay as measured from the ES reaction rate under the no-oscillation assumption is consistent with the high precision ES measurement by the Super-Kamiokande experiment. The {nu}{sub e} flux deduced from the CC reaction rate in SNO differs from the Super-Kamiokande ES results by 3.3{sigma}. This is evidence for an active neutrino component, in additional to {nu}{sub e}, in the solar neutrino flux. These results also allow the first experimental determination …
Date: September 24, 2001
Creator: Ahmad, Q. R.; Allen, R. C.; Andersen, T. C.; Anglin, J. D.; Barton, J. C.; Beier, E. W. et al.
Object Type: Article
System: The UNT Digital Library