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A 1-D model for highly sensitive tubular reactors
We consider the steady state operation of wall-cooled, fixed-bed tubular reactors. In these reactors the temperature rise ..delta..T must normally be limited to small fractions of the adiabatic temperature rise ..delta..T/sub ad/, both to avoid runaway and maintain product selectivity. Yet ..delta..T/..delta..T/sub ad/ << 1 can only occur if eta = t/sub dif//t/sub reac/ << 1, where t/sub dif/ is the timescale on which heat escapes the reactor by ''diffusing'' to the cooled walls, and t/sub reac/ is the timescale over which the reaction occurs. So here we use asymptotic methods based on eta << 1 to analyze the 2-d reactor equations, and find the radial concentration and temperature profiles to leading order in eta. We then obtain a 1-d model of the reactor by substituting these asymptotically correct profiles into the reactor equations and averaging over r. This model, the ..cap alpha..-model, is identical to the standard (Beek and Singer) 1-d model, except that the reactor's overall heat transfer coefficient U is a decreasing function of the temperature rise ..delta..T. This occurs because as ..delta..T increases, the reaction becomes increasingly concentrated near r = 0, causing a decreased heat transfer efficiency through the reactor's walls. By comparing it with …
Date:
January 1, 1987
Creator:
Hagan, P. S.; Herskowitz, M. & Pirkle, J. C.
Object Type:
Article
System:
The UNT Digital Library
4,5-methylenedithio-4',5'-propylenedithiotetrathiafulvalene (MPT) and 4,5-ethylenedithio-4',5'-propylenedithiotetrathiafulvalene (EPT)
The title electron donors, unsymmetrical analogs of Bis(ethylenedithio)tetrathiafulvalene, are synthesized. The utility of /sup 252/Cf Plasma Desorption Mass Spectrometry in the characterization and purity determinations is also reported.
Date:
January 1, 1987
Creator:
Kini, A. M.; Tytko, S. F.; Hunt, J. E. & Williams, J. M.
Object Type:
Article
System:
The UNT Digital Library
1987 Oak Ridge model conference: Proceedings: Volume 2, Environmental protection
See the abstract for Volume I for general information on the conference. Topics discussed in Volume II include data management techiques for environmental protection efforts, the use of models in environmental auditing, in emergency plans, chemical accident emergency response, risk assessment, monitoring of waste sites, air and water monitoring of waste sites, and in training programs. (TEM)
Date:
January 1, 1987
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
1987 Oak Ridge model conference: Proceedings: Volume I, Part 2, Waste Management
A conference sponsored by the United States Department of Energy (DOE) was held on Waste Mangement. Topics discussed were waste stabilization technologies regulations and standards, innovative treatment technology, waste stabilization projects. Individual projects are processed separately for the data bases. (CBS)
Date:
January 1, 1987
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
1987 Oak Ridge model conference: Proceedings: Volume I, Part 3, Waste Management
A conference sponsored by the United States Department of Energy (DOE), was held on waste management. Topics of discussion were transuranic waste management, chemical and physical treatment technologies, waste minimization, land disposal technology and characterization and analysis. Individual projects are processed separately for the data bases. (CBS)
Date:
January 1, 1987
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
²³⁵U(n,f), ²³⁸U(n, gamma), ²³⁸U(n,f), ²³⁹Pu(n,f) Reaction Rate Measurement Calibrations at ZPPR
New reference deposits for uranium-235, plutonium-239 and uranium-238 have been established with mass uncertainties of <0.2%. These new deposits replace the older reference deposits which were used during the last 17 years and improve the uncertainty of reaction rate measurements due to reference mass uncertainties by about a factor of 6. Measurements of the fission fragment absorption in 2 pi and low-geometry count rates. Two measurements of the uranium-238 capture rate in depleted uranium samples based upon the thermal cross sections of uranium-238(n, gamma), uranium-235(n,f) and plutonium-239(n,f) and based upon the americium-243 calibration technique confirm the ZPPR measurement technique within the quoted uncertainty of +/-0.5%
Date:
January 1987
Creator:
Poenitz, W. P.; Maddison, D. W.; Gasidlo, J. M.; Carpenter, S.G. & Armani, R. J.
Object Type:
Report
System:
The UNT Digital Library
28th Annual Report
The ACIR Library is composed of publications that study the interactions between different levels of government. This document is an annual report.
Date:
January 1987
Creator:
United States. Advisory Commission on Intergovernmental Relations.
Object Type:
Book
System:
The UNT Digital Library
Ab initio methods for electron-molecule collisions
This review concentrates on the recent advances in treating the electronic aspect of the electron-molecule interaction and leaves to other articles the description of the rotational and vibrational motions. Those methods which give the most complete treatment of the direct, exchange, and correlation effects are focused on. Such full treatments are generally necessary at energies below a few Rydbergs (approx. = 60 eV). This choice unfortunately necessitates omission of those active and vital areas devoted to the development of model potentials and approximate scattering formulations. The ab initio and model approaches complement each other and are both extremely important to the full explication of the electron-scattering process. Due to the rapid developments of recent years, the approaches that provide the fullest treatment are concentrated on. 81 refs.
Date:
January 1, 1987
Creator:
Collins, L. A. & Schneider, B. I.
Object Type:
Article
System:
The UNT Digital Library
Abilene Philharmonic Playbill: January 31-February 28, 1987
Program for an Abilene Philharmonic concert that ran from January 31st to February 28th (Series A fifth concert and Series B sixth concert) during the 37th season. It includes information about the pieces performed, artists and musicians, and advertising from local companies.
Date:
January 1987
Creator:
Abilene Philharmonic
Object Type:
Pamphlet
System:
The Portal to Texas History
Absorption edge imaging of sporocide-treated and non-treated bacterial spores
When deprived of nutrients, spore forming bacilli produce endospores which are remarkably resistant to chemical sterilization. Little is known about the morphology and response fo these spores following exposure to sporocidal agents. Light microscopy does not provide sufficient resolution for studying the rupture of the spore coat and fate of intracellular material. Transmission and scanning electron microscopy offer superior resolution but require specimen preparation methods that induce physiologic as well as morphologic changes in the spores, thereby making accurate interpretation of micrographs difficult. To eliminate the possible artifacts induced by chemical fixation, dehydration, embeddment, staining and sectioning, treated and non-sporocide-treated endospores of B. thuringiensis and B. subtilis were imaged by x-ray contact microscopy using monochromatic x-rays. 6 refs., 2 figs.
Date:
January 1, 1987
Creator:
Panessa-Warren, Barbara J.; Tortora, George T. & Warren, John B.
Object Type:
Article
System:
The UNT Digital Library
Abstracts for new opportunities in chemistry: An international symposium on the uses of synchrotron radiation in chemistry, November 4-6, 1987
Seventy-eight summaries of presentations are included. (DLC)
Date:
January 1, 1987
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Abstracts of Phase 1 awards, (fiscal year) 1987
Contained in this booklet are abstracts of the Phase I awards made in Fiscal Year 1987 under the Small Business Innovation Research (SBIR) program in the Department of Energy (DOE). The program is designed for implementation in a three-phase process, with Phase I determining the scientific or technical merit and feasibility of ideas proposed for investigation. The period of performance in this initial phase is relatively brief, typically about 6 months, and the awards are limited to $50,000. Phase II is the principal research or research and development effort, and the awards are as high as $500,000 for work to be performed in periods of up to 2 years. Phase III is the commercial application. The 111 Phase I projects described were selected in a highly competitive process from a total of 942 proposals received in response to the 1987 Solicitation. They cover the fields of chemistry, materials, control systems, plant natural products, instrumentation, nuclear medicine, health and environmental effects, high energy physics, particle accelerators, nuclear physics, plasma diagnostics and confinement, fusion energy systems, robotics and remote systems, nuclear reactors, space nuclear power, fuel cycle, decontamination/decommissioning, commputers in nuclear plants, coal, enhanced oil recovery/tar sands, fossil energy, photovoltaics, solar thermal, …
Date:
January 1, 1987
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Accelerator based coal positron beams
Cold positron beams produced using solid state moderators have been used profitably for condensed matter and positronium research. The low emittance and energy spread of these beams make the technique attractive as a potential positron source for future linear colliders, reducing or eliminating the need for damping rings. However, the intensities attained so far fall short of the requirements of a high energy linear collider. (approx.10/sup 11/ positrons/pulse at 10 kHz was taken as the positron flux necessary for a linear collider-B anti B factory). This report briefly reviews the state of the art in accelerator produced coal positron beams and indicates some areas in which yields might be improved. The discussion here is limited to electroproduced positrons.
Date:
January 1, 1987
Creator:
Schoessow, P. & Simpson, J.
Object Type:
Article
System:
The UNT Digital Library
Acceptance criteria considerations for miscellaneous wastes
EPA standards set forth limitations regarding releases to the accessible environment adjacent to a geologic repository. The NRC criteria pertaining to waste form and engineered barrier performance place certain restrictions on the physical and chemical nature of the waste form and require substantially complete confinement of radioactivity until the high-heat-production period is past. After this period, the annual release of radionuclides from the waste package is normally limited to 1 part in 100,000 of the amounts calculated to be present at 1000-y decay. The regulation permits deviation from these criteria in exceptional circumstances. One such circumstance might be the absence of a significant perturbation in temperature around the stored waste. The lack of significant heat release will eliminate the hydrologic driving force for dispersal of radionuclides. Exceptional circumstances which potentially could justify a less stringent long-term release criterion are: small quantity of radioactivity, the nature of the radioactive species, and the nature of the geology in which the waste is to be emplaced. Because the MW after a suitable decay period have low heat release rates per unit volume, they apparently could be so emplaced in a repository that there would be no compelling need, according to the reasoning presented …
Date:
January 1, 1987
Creator:
Irvine, A.R. & Forsberg, C.W.
Object Type:
Article
System:
The UNT Digital Library
The Accident Sequence Precursor program: Methods improvements and current results
Changes in the US NRC Accident Sequence Precursor program methods since the initial program evaluations of 1969-81 operational events are described, along with insights from the review of 1984-85 events. For 1984-85, the number of significant precursors was consistent with the number observed in 1980-81, dominant sequences associated with significant events were reasonably consistent with PRA estimates for BWRs, but lacked the contribution due to small-break LOCAs previously observed and predicted in PWRs, and the frequency of initiating events and non-recoverable system failures exhibited some reduction compared to 1980-81. Operational events which provide information concerning additional PRA modeling needs are also described.
Date:
January 1, 1987
Creator:
Minarick, J. W.; Manning, F. M. & Harris, J. D.
Object Type:
Article
System:
The UNT Digital Library
Acquisition of powder diffraction data with synchrotron radiation
During the past year, a dedicated triple-axis powder diffractometer has been in routine operation at the Brookhaven National Synchrotron Light Source as a user-oriented facility. The diffractometer is designed to allow easy interchange between energy-dispersive and monochromatic beam experiments. In the latter mode of operation, high resolution data have been collected for a variety of samples with the use of the crystal-analyzer technique, and in several cases these data sets have been used successfully for structure solution and Rietveld refinement. Several aspects of data acquisition at a synchrotron beam-line are described, and some of the different types of scattering geometry which have been used are discussed. Simple expressions are given for the instrumental resolution function expressed as the angular variation of peak widths for each of these. The peak shapes observed for a reference sample of Si on the present triple-axis instrument are well-described by the convolution of Gaussian and Lorentzian functions, and the angular dependence of the Gaussian component is in excellent agreement with the corresponding calculated instrumental function. One of the most important considerations for each type of experiment is the necessary compromise between intensity and resolution over a wide range of scattering angles, and some of the …
Date:
January 1, 1987
Creator:
Cox, D. E.; Toby, B. H. & Eddy, M. M.
Object Type:
Article
System:
The UNT Digital Library
Actinides and heavy fermions. [Th/sub x/U/sub 1-x/Be/sub 13/]
The actinide series of elements begins with f-shell electrons forming energy bands, contributing to the bonding, and possessing no magnetic moments. At americium the series switches over to localized f electrons with magnetic moments. In metallic compounds this crossover of behavior can be modified and studied. In this continuum of behavior a few compounds on the very edge of localized f-electron behavior exhibit enormous electronic heat capacities at low temperatures. This is associated with an enhanced thermal mass of the conduction electrons, which is well over a hundred times the free electron mass, and is what led to the label heavy fermion for such compounds. A few of these become superconducting at even lower temperatures. The excitement in this field comes from attempting to understand how this heaviness arises and from the likelihood that the superconductivity is different from that of previously known superconductors. The effects of thorium impurities in UBe/sub 13/ were studied as a representative system for studying the nature of the superconductivity.
Date:
January 1, 1987
Creator:
Smith, J.L.; Fisk, Z. & Ott, H.R.
Object Type:
Article
System:
The UNT Digital Library
ACTVE News, Volume 18, Number 1, January/February 1987
Newsletter issued by the Advisory Council for Technical-Vocational Education in Texas discussing news, events, and other relevant information related to technical and vocational education for adults in Texas.
Date:
1987-01/1987-02
Creator:
Advisory Council for Technical-Vocational Education in Texas
Object Type:
Journal/Magazine/Newsletter
System:
The Portal to Texas History
Adaptive control technique for accelerators using digital signal processing
The use of present Digital Signal Processing (DSP) techniques can drastically reduce the residual rf amplitude and phase error in an accelerating rf cavity. Accelerator beam loading contributes greatly to this residual error, and the low-level rf field control loops cannot completely absorb the fast transient of the error. A feedforward technique using DSP is required to maintain the very stringent rf field amplitude and phase specifications. 7 refs.
Date:
January 1, 1987
Creator:
Eaton, L.; Jachim, S. & Natter, E.
Object Type:
Article
System:
The UNT Digital Library
ADGEN: An automated adjoint code generator for large-scale sensitivity analysis
This paper describes a new automated system, named ADGEN, which makes use of the strengths of computer calculus to automate the costly and time-consuming calculation of derivatives in FORTRAN computer codes, and automatically generate adjoint solutions of computer codes.
Date:
January 1, 1987
Creator:
Pin, F. G.; Oblow, E. M.; Horwedel, J. E. & Lucius, J. L.
Object Type:
Article
System:
The UNT Digital Library
An Advanced Hadron Facility: Prospects and applicability to antiproton production
An Advanced Hadron Facility is designed to address physics problems within and beyond the Standard Model. High fluxes of secondary beams are needed for the requisite precision tests and searches for very rare decay modes of mesons and baryons. Such high fluxes at useful secondary energies are readily obtained from high intensity, intermediate energy proton beams, which are also well suited to antiproton production. If the AHF primary proton beam were merely dumped into a beam stop, it would produce on the order of 10/sup 19/ to 10/sup 20/ antiprotons per operating year. Current collection techniques are not likely to be capable of absorbing more than one part in 10/sup 3/ of this production. Thus, an AHF provides both the immediate possibility of collecting quantities of antiprotons substantially beyond those available from the LEF discussed at this meeting, and for significant increases in the available antiproton supply upon the development (at an AHF) of more efficient collection methods. The prospects are presently good for the completion of an AHF in the late 1990's.
Date:
January 1, 1987
Creator:
Goldman, T.
Object Type:
Article
System:
The UNT Digital Library
Advanced Stirling conversion systems for terrestrial applications
Sandia National Laboratories (SNLA) is developing heat engines for terrestrial Solar distributed Heat Receivers. SNLA has identified the Stirling to be one of the most promising candidates for the terrestrial applications. The free-piston Stirling engine (FPSE) has the potential to meet the DOE goals for both performance and cost. Free-piston Stirling activities which are directed toward a dynamic power source for the space application are being conducted. Space power system requirements include high efficiency, very long life, high reliability and low vibration. The FPSE has the potential for future high power space conversion systems, either solar or nuclear powered. Generic free-piston technology is currently being developed for use with a residential heat pump under an Interagency Agreement. Also, an overview is presented of proposed conceptual designs for the Advanced Stirling Conversion System (ASCS) using a free-piston Stirling engine and a liquid metal heat pipe receiver. Power extraction includes both a linear alternator and hydraulic output capable of delivering approximately 25 kW of electrical power to the electric utility grid. Target cost of the engine/alternator is 300 dollars per kilowatt at a manufacturing rate of 10,000 units per year. The design life of the ASCS is 60,000 h (30 y) with …
Date:
January 1, 1987
Creator:
Shaltens, R.K.
Object Type:
Article
System:
The UNT Digital Library
Advanced toroidal facility vaccuum vessel stress analyses
The complex geometry of the Advance Toroidal Facility (ATF) vacuum vessel required special analysis techniques in investigating the structural behavior of the design. The response of a large-scale finite element model was found for transportation and operational loading. Several computer codes and systems, including the National Magnetic Fusion Energy Computer Center Cray machines, were implemented in accomplishing these analyses. The work combined complex methods that taxed the limits of both the codes and the computer systems involved. Using MSC/NASTRAN cyclic-symmetry solutions permitted using only 1/12 of the vessel geometry to mathematically analyze the entire vessel. This allowed the greater detail and accuracy demanded by the complex geometry of the vessel. Critical buckling-pressure analyses were performed with the same model. The development, results, and problems encountered in performing these analyses are described. 5 refs., 3 figs.
Date:
January 1, 1987
Creator:
Hammonds, C.J. & Mayhall, J.A.
Object Type:
Article
System:
The UNT Digital Library
Advances in explosively formed fuse opening switches
The development of Explosively Formed Fuses along two separate lines is discussed. One design, which has previously been demonstrated to conduct a 9.5 MA 350 ..mu..s risetime pulse and interrupt it in 1.2 ..mu..s. This scaled up design should operate at up to 15 MA with 20 nH loads. A second design with enhanced performance characteristics is being examined and will be tested on a small scale. This design includes opening switch inductance as part of the inductive store and, as a result, should have shorter pulse transfer times and should be able to be scaled to handle currents up to approx. 25 MA with 20 nH loads.
Date:
January 1, 1987
Creator:
Goforth, J. H.; Caird, R. S.; Greene, A. E.; Lindemuth, I. R.; Marsh, S. P.; Oona, H. et al.
Object Type:
Article
System:
The UNT Digital Library