Tests of a mechanism for H sub 2 S release during coal pyrolysis (open access)

Tests of a mechanism for H sub 2 S release during coal pyrolysis

We have used a temperature programmed, gas evolution technique to compare H{sub 2}S from coal and from pyrite in the presence of minerals or polymers. Pyrite decomposition in coal with H{sub 2}S release can be observed directly only if carbonate minerals, particularly iron-containing carbonates, are absent. Two distinct chemical mechanisms are required to model conversion of pyrite in coal to H{sub 2}S and pyrrhotite. Initially a reaction at pyrite grain surfaces (shrinking core model) occurs that is controlled by the rate of iron movement toward crystallite centers and by hydrogen-donor availability. Tar evolution (as indicated by methane-plus-ethane) also requires H-donors. Organic free radicals compete so efficiently for this scarce commodity that the rate of pyrite decomposition slows. At a 10 K/min heating rate, the rate of H{sub 2}S release by the H-donor mechanism reaches a maximum at 700 K and then decreases. Unimolecular decomposition of coal pyrite to FeS and S{sub 2} then occurs sharply at 830 K. Coal pyrolysis products effectively capture S{sub 2}, and the rate of H{sub 2}S release matches that of sulfur release from pure pyrite in a vacuum (0.07 mg- S/cm{sup 2}/min at 773 K). The high temperature H{sub 2}S evolution peak from coal is …
Date: May 31, 1991
Creator: Coburn, T. T.; Foster, K. G.; Gregg, H. R. & Lindsey, J. A.
System: The UNT Digital Library
Computational simulations of plasma flow switches and imploding loads (open access)

Computational simulations of plasma flow switches and imploding loads

The Procyon system in the Los Alamos Trailmaster foil implosion project is intended to produce soft x-ray radiation by delivering about 1 MJ of kinetic energy to an imploding plasma liner. The final switching stage of this system will be a Plasma Flow Switch (PFS) which delivers current to the cylindrical foil load. 1-D and 2-D simulations are now being conducted to examine: the initiation of the PFS plasma: the dynamics of the PFS and its switching efficiency; the load implosion and resulting radiation output. Considered here, for the PFS and imploding load, are the effects of electrode walls, perturbations, and radiation. Comparisons with experiments (using the 1.5 MJ Pegasus capacitor bank) are also described. 5 refs., 6 figs.
Date: May 29, 1991
Creator: Peterson, D. L.; Bowers, R. L.; Brownell, J. H.; Greene, A. E. & Roderick, N. F.
System: The UNT Digital Library
Broadband diffractive lens (open access)

Broadband diffractive lens

Significant progress has been made toward solving the century-old problem of chromatic aberrations in diffractive optics. Our approach exploits modern materials and microfabrication technology and is very different from the purely diffractive strategy,'' which is commonly employed and which results in multiple diffractive elements separated by a finite distance. We have developed a Fresnel zone plate lens comprised of a serial stack of patterned minus-filters which allows broadband radiation to be focused (or imaged) without longitudinal or transverse chromatic aberrations. 7 refs., 4 figs.
Date: May 28, 1991
Creator: Ceglio, N. M.; Hawryluk, A. M.; London, R. A.; Seppala, L. G. (Lawrence Livermore National Lab., CA (USA)) & Gaines, D. P. (Brigham Young Univ., Provo, UT (USA))
System: The UNT Digital Library
Laser produced plasma soft x-ray generation (open access)

Laser produced plasma soft x-ray generation

The efficiency of soft x-ray production from laser-irradiated plasmas is simulated for two different spectral regions. These two regions, 14{Angstrom} {plus minus} 15% and 130{Angstrom} {plus minus} 1%, were chosen for proximity mask or point-projection technological applications. Relatively large conversion efficiencies were obtained from irradiation of a stainless steel target using the conditions suggested by recent Hampshire Instruments' experiments for proximity masking. Pulse-width and laser frequency parameter studies were performed for point-projection applications which suggest that the conversion applications which suggest that the conversion efficiency is sensitive to pulse-width but not to laser frequency. One of the critical components of any x-ray lithographic scheme is of course the x-ray laser source. There are two primary contenders for a reliable, efficient source currently: synchrotron radiation and spectral emission from laser produced plasma. The dominant issue for laser-plasma emission is the conversion efficiency -- output in the intended operating spectral region relative the required incident laser energy. Simulations are described in the following for both high and low energy spectral regions which have been suggested by either the proximity masking or point-projection technology.
Date: May 20, 1991
Creator: Cerjan, C. & Rosen, M.D.
System: The UNT Digital Library
Mixed waste treatment with a mediated electrochemical process (open access)

Mixed waste treatment with a mediated electrochemical process

The process described in this paper is intended to convert mixed waste containing toxic organic compounds (not heavy metals) to ordinary radioactive waste, which is treatable. The process achieves its goal by oxidizing hydrocarbons to CO{sub 2} and H{sub 2}O. Other atoms that may be present in the toxic organic generally are converted to nonhazardous anions such as sulfate and phosphate. This electro chemical conversion is performed at conditions of temperature and pressure that are just moderately above ambient conditions. Gaseous hydroxides and oxyhydroxides that are formed by many radionuclides during incineration cannot form in this process. 1 ref., 3 figs.
Date: May 17, 1991
Creator: Hickman, R. G.; Gray, L. W. & Chiba, Z.
System: The UNT Digital Library
IOGCC/DOE oil and gas environmental workshop (open access)

IOGCC/DOE oil and gas environmental workshop

The Interstate Oil and Gas Compact Commission (IOGCC) in cooperation with US Department of Energy (DOE) has developed a workshop format to allow state regulatory officials and industry representatives the opportunity to participate in frank and open discussions on issues of environmental regulatory compliance. The purpose in providing this forum is to assist both groups in identifying the key barriers to the economic recoverability of domestic oil and gas resources while adequately protecting human health and the environment. The following topics were discussed, groundwater protection; temporarily abandoned and idle wells; effluent discharges; storm water runoff; monitoring and compliance; wetlands; naturally occurring radioactive materials; RCRA reauthorization and oil pollution prevention regulation. At the conclusion, all of the participants were asked to complete a questionnaire which critiqued the day activities. A discussion of each of the issues is made a part of this report as is a summary of the critique questionnaire which were received.
Date: May 16, 1991
Creator: unknown
System: The UNT Digital Library
Molten salt processing of mixed wastes with offgas condensation (open access)

Molten salt processing of mixed wastes with offgas condensation

We are developing an advanced process for treatment of mixed wastes in molten salt media at temperatures of 700--1000{degrees}C. Waste destruction has been demonstrated in a single stage oxidation process, with destruction efficiencies above 99.9999% for many waste categories. The molten salt provides a heat transfer medium, prevents thermal surges, and functions as an in situ scrubber to transform the acid-gas forming components of the waste into neutral salts and immobilizes potentially fugitive materials by a combination of particle wetting, encapsulation and chemical dissolution and solvation. Because the offgas is collected and assayed before release, and wastes containing toxic and radioactive materials are treated while immobilized in a condensed phase, the process avoids the problems sometimes associated with incineration processes. We are studying a potentially improved modification of this process, which treats oxidizable wastes in two stages: pyrolysis followed by catalyzed molten salt oxidation of the pyrolysis gases at ca. 700{degrees}C. 15 refs., 5 figs., 1 tab.
Date: May 13, 1991
Creator: Cooper, J.F.; Brummond, W.; Celeste, J.; Farmer, J.; Hoenig, C.; Krikorian, O.H. et al.
System: The UNT Digital Library
Estimating market penetration of new district heating and cooling systems using a combination of economic cost and diffusion models (open access)

Estimating market penetration of new district heating and cooling systems using a combination of economic cost and diffusion models

The economic-cost model and the diffusion model are among the many market-penetration forecasting approaches that are available. These approaches have been used separately in many applications. In this paper, the authors briefly review these two approaches and then describe a methodology for forecasting market penetration using both approaches sequentially. This methodology is illustrated with the example of market-penetration forecasting of new district heating and cooling (DHC) systems in the Argonne DHC Market Penetration Model, which was developed and used over the period 1979--1983. This paper discusses how this combination approach, which incorporates the strengths of the economic-cost and diffusion models, has been superior to any one approach for market forecasts of DHC systems. Also discussed are the required modifications for revising and updating the model in order to generate new market-penetration forecasts for DHC systems. These modifications are required as a result of changes in DHC engineering, economic, and market data from 1983 to 1990. 13 refs., 5 figs., 2 tabs.
Date: May 10, 1991
Creator: Teotia, Arvind P. S. & Karvelas, Dimitrios E.
System: The UNT Digital Library
Application of muon spin relaxation experiment to the mixed state superconductors (open access)

Application of muon spin relaxation experiment to the mixed state superconductors

We discuss the use of muon spin relaxation ({mu}{sup +}SR) technique to study the mixed state of superconductors. Besides the application for static vortex configurations, we argue that large vortex motion can manifest itself as a narrowed time-averaged field distribution, which in turn results in a smaller relaxation rate. A static but disordered vortex configuration can also reduce the relaxation. We summarize these arguments. 7 refs.
Date: May 9, 1991
Creator: Inui, M. (Los Alamos National Lab., NM (USA)) & Harshman, D.R. (AT and T Bell Labs., Murray Hill, NJ (USA))
System: The UNT Digital Library
Modular invariant gaugino condensation (open access)

Modular invariant gaugino condensation

The construction of effective supergravity lagrangians for gaugino condensation is reviewed and recent results are presented that are consistent with modular invariance and yield a positive definite potential of the noscale type. Possible implications for phenomenology are briefly discussed. 29 refs.
Date: May 9, 1991
Creator: Gaillard, M. K.
System: The UNT Digital Library
Nuclear hazardous waste cost control management (open access)

Nuclear hazardous waste cost control management

The effects of the waste content of glass waste forms on Savannah River high-level waste disposal costs are currently under study to adjust the glass frit content to optimize the glass waste loadings and therefore significantly reduce the overall waste disposal cost. Changes in waste content affect onsite Defense Waste Changes in waste contents affect onsite Defense Waste Processing Facility (DWPF) costs as well as offsite shipping and repository emplacement charges. A nominal 1% increase over the 28 wt% waste loading of DWPF glass would reduce disposal costs by about $50 million for Savannah River wastes generated to the year 2000. Optimization of the glass waste forms to be produced in the SWPF is being supported by economic evaluations of the impact of the forms on waste disposal costs. Glass compositions are specified for acceptable melt processing and durability characteristics, with economic effects tracked by the number of waste canisters produced. This paper presents an evaluation of the effects of variations in waste content of the glass waste forms on the overall cost of the disposal, including offsite shipment and repository emplacement, of the Savannah River high-level wastes.
Date: May 9, 1991
Creator: Selg, R.A.
System: The UNT Digital Library
Nuclear hazardous waste cost control management (open access)

Nuclear hazardous waste cost control management

The effects of the waste content of glass waste forms on Savannah River high-level waste disposal costs are currently under study to adjust the glass frit content to optimize the glass waste loadings and therefore significantly reduce the overall waste disposal cost. Changes in waste content affect onsite Defense Waste Changes in waste contents affect onsite Defense Waste Processing Facility (DWPF) costs as well as offsite shipping and repository emplacement charges. A nominal 1% increase over the 28 wt% waste loading of DWPF glass would reduce disposal costs by about $50 million for Savannah River wastes generated to the year 2000. Optimization of the glass waste forms to be produced in the SWPF is being supported by economic evaluations of the impact of the forms on waste disposal costs. Glass compositions are specified for acceptable melt processing and durability characteristics, with economic effects tracked by the number of waste canisters produced. This paper presents an evaluation of the effects of variations in waste content of the glass waste forms on the overall cost of the disposal, including offsite shipment and repository emplacement, of the Savannah River high-level wastes.
Date: May 9, 1991
Creator: Selg, R. A.
System: The UNT Digital Library
Vacuum System of the High Energy Ring of an Asymmetric B-Factory Based on Pep (open access)

Vacuum System of the High Energy Ring of an Asymmetric B-Factory Based on Pep

The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs.
Date: May 7, 1991
Creator: Barletta, W. A.; Calderon, M. O.; Wong, R. & Jenkins, T. M.
System: The UNT Digital Library
Apiary B Factory Lattice Design (open access)

Apiary B Factory Lattice Design

The Apiary B Factory is a proposed high-intensity electron-positron collider. This paper presents the lattice design for this facility, which envisions two rings with unequal energies in the PEP tunnel. The design has many interesting optical and geometrical features due to the needs to conform to the existing tunnel, and to achieve the necessary emittances, damping times and vacuum. Existing hardware is used to a maximum extent.
Date: May 3, 1991
Creator: Donald, M. H. R. & Garren, A. A.
System: The UNT Digital Library
Optical analogs of model atoms in fields (open access)

Optical analogs of model atoms in fields

The equivalence of the paraxial wave equation to a time-dependent Schroedinger equation is exploited to construct optical analogs of model atoms in monochromatic fields. The approximation of geometrical optics provides the analog of the corresponding classical mechanics. Optical analogs of Rabi oscillations, photoionization, stabilization, and the Kramers-Henneberger transformation are discussed. One possibility for experimental realization of such optical analogs is proposed. These analogs may be useful for studies of quantum chaos'' when the ray trajectories are chaotic. 9 refs.
Date: May 2, 1991
Creator: Milonni, P.W.
System: The UNT Digital Library
A 10,000 A 1000 VDC solid state dump switch (open access)

A 10,000 A 1000 VDC solid state dump switch

The superconducting magnet test program at Fermilab requires a switch, called a dump switch, rated 10,000 A, 1000 Vdc, which must be able to continuously carry rated current. A dump resistor rated 2 MJoules, is connected in parallel with the switch contacts and dissipates the stored energy from a magnet when the switch opens. The required switch opening time is 250 {mu}sec maximum after detection of a fault or a trip command. A successful switch can be constructed from six parallel inverter type Silicon Controlled Rectifiers (SCR's) which each carry their share of the load current. These run SCR's are mounted at watercooled heatsinks and are commutated off from stored energy in capacitors. Each parallel SCR is connected in series with a 1 m{Omega} watercooled resistor to assure dc current sharing and turn on. A description of the control and construction of the switch is presented. 6 figs.
Date: May 1, 1991
Creator: Visser, A.
System: The UNT Digital Library
100 MW klystron development at SLAC (open access)

100 MW klystron development at SLAC

A klystron designed to operate at 11.4 GHz and 440 kV is presently SLAC's strongest rf power source candidate for the Next Linear Collider. It is expected to provide 100 MW of rf power with a pulse width of 1 microsecond. Many of the conventional tube technologies are being pushed to their limits. High electron beam power densities, rf electric gradients in cavity gaps and stresses on the ceramic rf output windows are among the most severe problems to be dealt with. This paper describes progress in the development of this device including results from single and double gap output cavities and various styles of rf output windows. 6 refs., 3 figs., 1 tab.
Date: May 1, 1991
Creator: Vlieks, A. E.; Callin, R. S.; Caryotakis, G.; Fant, K. S.; Fowkes, W. R.; Lee, T. G. et al.
System: The UNT Digital Library
350 MW(t) MHTGR preassembly and modularization (open access)

350 MW(t) MHTGR preassembly and modularization

The Modular High Temperature Gas Cooled Reactor (MHTGR) provides a safe and economical nuclear power option for the world's electrical generation needs by the turn of the century. The proposed MHTGR plant is composed of four 350 MW(t) prismatic core reactor modules, coupled to a 2(2 {times} 1) turbine generator producing a net plant electrical output of 538 MW(e). Each of the four reactor module is located in a below-ground level concrete silo, and consists of a reactor vessel and a steam generator vessel interconnected by a cross duct vessel. The modules, along with the service buildings, are contained within a Nuclear Island (NI). The turbine generators and power generation facilities are in the non-nuclear Energy Conversion Area (ECA). The MHTGR design reduces cost and improves schedule by maximizing shop fabrication, minimizing field fit up of the Reactor Internals components and modularizing the NI ECA facilities. 3 refs., 6 figs., 2 tabs.
Date: May 1, 1991
Creator: Venkatesh, M.C. (General Atomics, San Diego, CA (USA)); Jones, G. (Gas-Cooled Reactor Associates, San Diego, CA (USA)); Dilling, D.A. (Bechtel International Corp., San Francisco, CA (USA)) & Parker, W.J. (Stone and Webster Engineering Corp., Boston, MA (USA))
System: The UNT Digital Library
3D numerical thermal stress analysis of the high power target for the SLC Positron Source (open access)

3D numerical thermal stress analysis of the high power target for the SLC Positron Source

The volumetrically nonuniform power deposition of the incident 33 GeV electron beam in the SLC Positron Source Target is hypothesized to be the most likely cause target failure. The resultant pulsed temperature distributions are known to generate complicated stress fields with no known closed-form analytical solution. 3D finite element analyses of these temperature distributions and associated thermal stress fields in the new High Power Target are described here. Operational guidelines based on the results of these analyses combined with assumptions made about the fatigue characteristics of the exotic target material are proposed. 6 refs., 4 figs.
Date: May 1, 1991
Creator: Reuter, E.M. & Hodgson, J.A.
System: The UNT Digital Library
Accelerator and feedback control simulation using neural networks (open access)

Accelerator and feedback control simulation using neural networks

Unlike present constant model feedback system, neural networks can adapt as the dynamics of the process changes with time. Using a process model, the Accelerator'' network is first trained to simulate the dynamics of the beam for a given beam line. This Accelerator'' network is then used to train a second Controller'' network which performs the control function. In simulation, the networks are used to adjust corrector magnetics to control the launch angle and position of the beam to keep it on the desired trajectory when the incoming beam is perturbed. 4 refs., 3 figs.
Date: May 1, 1991
Creator: Nguyen, D.; Lee, M.; Sass, R. & Shoaee, H.
System: The UNT Digital Library
Accelerator Simulation and Operation Via. Identical Operational Interfaces (open access)

Accelerator Simulation and Operation Via. Identical Operational Interfaces

The CEBAF accelerator contains approximately 2500 power supplies, 340 klystrons, and 800 beam monitors. The operation of such a complex machine requires a control system which can provide a high degree of automation with strong support by simulation and modeling programs.\nWe present the architecture and first results of a control system which allows one the use of identical operation procedures and interfaces for operation of the real accelerator and high-level accelerator simulation programs. The interfaces were developed using TACL (Thaumaturgic Automated Control Logic) control software, developed at CEBAF for accelerator control. This setup provides the capability to: (1) test and debug the various operation procedures before the completion of the accelerator, (2) execute machine simulations under realistic environmental conditions, and (3) preview and evaluate the effectiveness of operational procedures during run time. The optimized simulation program adds only two seconds to
Date: May 1, 1991
Creator: Barry, Andrea; Bowling, Bruce; Lahti, George; Sage, Joan; Tang, Johnny; Kewisch, Jorg et al.
System: The UNT Digital Library
Achieving high luminosity in the Fermilab Tevatron (open access)

Achieving high luminosity in the Fermilab Tevatron

Fermilab has embarked upon a program, christened Fermilab III, to raise the luminosity in the Tevatron proton-antiproton collider over the next five years by at least a factor of thirty beyond the currently achieved level of 1.6{times}10{sup 30}cm{sup {minus}2}sec{sup {minus}1}. Components of the program include implementation of electrostatic separators, Antiproton Source improvements, installation of cold compressors, doubling the existing linac output energy, and the construction of a new accelerator--the Fermilab Main Injector. Basic limitations in the achievement of higher luminosity in the Tevatron, the strategy developed to achieve the Fermilab III goals, and the evolution of luminosity throughout the period will be discussed. 1 fig., 2 tabs.
Date: May 1, 1991
Creator: Holmes, S.D.
System: The UNT Digital Library
The Advanced Light Source (open access)

The Advanced Light Source

The Advanced Light Source (ALS), a national user facility currently under construction at the Lawrence Berkeley Laboratory (LBL), is a third-generation synchrotron light source designed to produce extremely bright beams of synchrotron radiation in the energy range from a few eV to 10 keV. The design is based on a 1--1.9-GeV electron storage ring (optimized at 1.5 GeV), and utilizes special magnets, known as undulators and wigglers (collectively referred to as insertion devices), to generate the radiation. The facility is scheduled to begin operating in April 1993. In this paper we describe the progress in the design, construction, and commissioning of the accelerator systems, insertion devices, and beamlines. Companion presentations at this conference give more detail of specific components in the ALS, and describe the activities towards establishing an exciting user program. 3 figs., 2 tabs.
Date: May 1, 1991
Creator: Jackson, A.
System: The UNT Digital Library
Alignment issues of the SLC linac accelerating structure (open access)

Alignment issues of the SLC linac accelerating structure

The accelerating structure of the Stanford Linear Collider (SLC) is required to be aligned to 100--200 {mu}m rms. Alignment at such a level will reduce transverse wakefield effects sufficiently so that only a small emittance enlargement of the beam is expected during acceleration to 50 GeV with up to 7 {times} 10{sup 10} particles per bunch. This report describes many aspects of the alignment including global alignment, local alignment, construction of the accelerating cavities, active controls of the structure alignment, external constraints, temperature and airflow effects, and alignment stability. 9 refs., 8 figs.
Date: May 1, 1991
Creator: Seeman, J. T.; Adolphsen, C.; Decker, F. J.; Fischer, G.; Hodgson, J.; Pennacchi, R. et al.
System: The UNT Digital Library