Resource Type

Accident consequences analysis of the HYLIFE-II inertial fusion energy power plant design (open access)

Accident consequences analysis of the HYLIFE-II inertial fusion energy power plant design

Previous studies of the safety and environmental (S and E) aspects of the HYLIFE-II inertial fusion energy (IFE) power plant design have used simplistic assumptions in order to estimate radioactivity releases under accident conditions. Conservatisms associated with these traditional analyses can mask the actual behavior of the plant and have revealed the need for more accurate modeling and analysis of accident conditions and radioactivity mobilization mechanisms. In the present work a set of computer codes traditionally used for magnetic fusion safety analyses (CHEMCON, MELCOR) has been applied for simulating accident conditions in a simple model of the HYLIFE-II IFE design. Here the authors consider a severe lost of coolant accident (LOCA) producing simultaneous failures of the beam tubes (providing a pathway for radioactivity release from the vacuum vessel towards the containment) and of the two barriers surrounding the chamber (inner shielding and containment building it self). Even though containment failure would be a very unlikely event it would be needed in order to produce significant off-site doses. CHEMCON code allows calculation of long-term temperature transients in fusion reactor first wall, blanket, and shield structures resulting from decay heating. MELCOR is used to simulate a wide range of physical phenomena including …
Date: February 23, 2000
Creator: Reyes, S; Gomez del Rio, J & Sanz, J
System: The UNT Digital Library
Accountability for network backup failures (open access)

Accountability for network backup failures

Regular hard disk backups for workstations are widely recommended. The necessity of backups -- akin to one`s own mortality -- is something most people would rather not think about. This attitude has two consequences. When people do subscribe to automated network backups, they expect the system to perform at a high level of reliability and that their files will be there for them when they need them. Second, they usually fail to appreciate that reliability is a shared responsibility. Although ostensibly their only responsibility is to keep the computer powered on overnight, there are actually many more opportunities for failure within the user`s jurisdiction than in other parts of the infrastructure. High reliability is almost a sine qua non for backups. We describe a strategy for enhancing reliability based on the principle of accountability. This strategy involves monitoring the system, gathering statistics, detecting problems, anticipating problems, troubleshooting, and finally determining where failure occurred within the infrastructure and who should be accountable. We describe a specific backup system in a specific network environment to illustrate the value of accountability. This system, macdumps, backs up Macintosh disks over an AppleTalk network. The original software was written by Dan Tappan of BBN in …
Date: February 1, 1994
Creator: Benson, W. H.
System: The UNT Digital Library
Accretion Column Structure of Magnetic Cataclysmic Variables from X-ray Spectroscopy (open access)

Accretion Column Structure of Magnetic Cataclysmic Variables from X-ray Spectroscopy

Using Chandra HETG data we present light curves for individual spectral lines of Mg XI and Mg XII for EX Hydrae, an intermediate-polar type cataclysmic variable. The Mg XI light curve, folded on the white dwarf spin period, shows two spikes that are not seen in the Mg XII or broad-band light curves. Occultation of the accretion column by the body of the white dwarf would produce such spikes for an angle between the rotation axis and the accretion columns of {alpha} = 18{sup o} and a height of the Mg XI emission above the white dwarf surface of {approx}< 0.0004 white dwarf radii or {approx}< 4 km. The absence of spikes in the Mg XII and broad-band light curves could then be explained if the bulk of its emission forms at much larger height, > 0.004 white dwarf radii or > 40 km, above the white dwarf surface. The technique described in this letter demonstrates that high signal-to-noise ratio and high spectral resolution X-ray spectra can be used to map the temperature and density structure of accretion flows in magnetic cataclysmic variables. The Mg XI and Mg XII light curves are not consistent with the temperature and density structure …
Date: February 27, 2006
Creator: Hoogerwerf, R; Brickhouse, N S & Mauche, C W
System: The UNT Digital Library
Accurate Astrometry and Photometry of Saturated and Coronagraphic Point Spread Functions (open access)

Accurate Astrometry and Photometry of Saturated and Coronagraphic Point Spread Functions

For ground-based adaptive optics point source imaging, differential atmospheric refraction and flexure introduce a small drift of the point spread function (PSF) with time, and seeing and sky transmission variations modify the PSF flux. These effects need to be corrected to properly combine the images and obtain optimal signal-to-noise ratios, accurate relative astrometry and photometry of detected companions as well as precise detection limits. Usually, one can easily correct for these effects by using the PSF core, but this is impossible when high dynamic range observing techniques are used, like coronagraphy with a non-transmissive occulting mask, or if the stellar PSF core is saturated. We present a new technique that can solve these issues by using off-axis satellite PSFs produced by a periodic amplitude or phase mask conjugated to a pupil plane. It will be shown that these satellite PSFs track precisely the PSF position, its Strehl ratio and its intensity and can thus be used to register and to flux normalize the PSF. This approach can be easily implemented in existing adaptive optics instruments and should be considered for future extreme adaptive optics coronagraph instruments and in high-contrast imaging space observatories.
Date: February 7, 2006
Creator: Marois, C; Lafreniere, D; Macintosh, B & Doyon, R
System: The UNT Digital Library
Accurate determination of Curium and Californium isotopic ratios by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 248Cm samples for transmutation studies (open access)

Accurate determination of Curium and Californium isotopic ratios by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 248Cm samples for transmutation studies

The French Atomic Energy Commission has carried out several experiments including the mini-INCA (INcineration of Actinides) project for the study of minor-actinide transmutation processes in high intensity thermal neutron fluxes, in view of proposing solutions to reduce the radiotoxicity of long-lived nuclear wastes. In this context, a Cm sample enriched in {sup 248}Cm ({approx}97 %) was irradiated in thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). This work describes a quadrupole ICP-MS (ICP-QMS) analytical procedure for precise and accurate isotopic composition determination of Cm before sample irradiation and of Cm and Cf after sample irradiation. The factors that affect the accuracy and reproducibility of isotopic ratio measurements by ICP-QMS, such as peak centre correction, detector dead time, mass bias, abundance sensitivity and hydrides formation, instrumental background, and memory blank were carefully evaluated and corrected. Uncertainties of the isotopic ratios, taking into account internal precision of isotope ratio measurements, peak tailing, and hydrides formations ranged from 0.3% to 1.3%. This uncertainties range is quite acceptable for the nuclear data to be used in transmutation studies.
Date: February 1, 2011
Creator: Gourgiotis, A.; Isnard, H.; Aubert, M.; Dupont, E.; AlMahamid, I.; Cassette, P. et al.
System: The UNT Digital Library
Accurate, reliable control of process gases by mass flow controllers (open access)

Accurate, reliable control of process gases by mass flow controllers

The thermal mass flow controller, or MFC, has become an instrument of choice for the monitoring and controlling of process gas flow throughout the materials processing industry. These MFCs are used on CVD processes, etching tools, and furnaces and, within the semiconductor industry, are used on 70% of the processing tools. Reliability and accuracy are major concerns for the users of the MFCs. Calibration and characterization technologies for the development and implementation of mass flow devices are described. A test facility is available to industry and universities to test and develop gas floe sensors and controllers and evaluate their performance related to environmental effects, reliability, reproducibility, and accuracy. Additional work has been conducted in the area of accuracy. A gravimetric calibrator was invented that allows flow sensors to be calibrated in corrosive, reactive gases to an accuracy of 0.3% of reading, at least an order of magnitude better than previously possible. Although MFCs are typically specified with accuracies of 1% of full scale, MFCs may often be implemented with unwarranted confidence due to the conventional use of surrogate gas factors. Surrogate gas factors are corrections applied to process flow indications when an MFC has been calibrated on a laboratory-safe surrogate …
Date: February 1, 1997
Creator: Hardy, J. & McKnight, T.
System: The UNT Digital Library
Achieving Agility Through Parameter Space Qualification (open access)

Achieving Agility Through Parameter Space Qualification

The A-primed (Agile Product Realization of Innovative electro-Mechanical Devices) project is defining and proving processes for agile product realization for the Department of Energy complex. Like other agile production efforts reported in the literature, A-primed uses concurrent engineering and information automation technologies to enhance information transfer. A unique aspect of our approach to agility is the qualification during development of a family of related product designs and their production processes, rather than a single design and its attendant processes. Applying engineering principles and statistical design of experiments, economies of test and analytic effort are realized for the qualification of the device family as a whole. Thus the need is minimized for test and analysis to qualify future devices from this family, thereby further reducing the design-to-production cycle time. As a measure of the success of the A-primed approach, the first design took 24 days to produce, and operated correctly on the first attempt. A flow diagram for the qualification process is presented. Guidelines are given for implementation, based on the authors experiences as members of the A-primed qualification team.
Date: February 1, 1995
Creator: Diegert, Kathleen V.; Easterling, Robert G.; Ashby, M. Rodema; Benavides, Gilbert L.; Forsythe, Chris; Jones, Rondall E. et al.
System: The UNT Digital Library
Achieving closure at Fernald (open access)

Achieving closure at Fernald

When Fluor Fernald took over the management of the Fernald Environmental Management Project in 1992, the estimated closure date of the site was more than 25 years into the future. Fluor Fernald, in conjunction with DOE-Fernald, introduced the Accelerated Cleanup Plan, which was designed to substantially shorten that schedule and save taxpayers more than $3 billion. The management of Fluor Fernald believes there are three fundamental concerns that must be addressed by any contractor hoping to achieve closure of a site within the DOE complex. They are relationship management, resource management and contract management. Relationship management refers to the interaction between the site and local residents, regulators, union leadership, the workforce at large, the media, and any other interested stakeholder groups. Resource management is of course related to the effective administration of the site knowledge base and the skills of the workforce, the attraction and retention of qualified a nd competent technical personnel, and the best recognition and use of appropriate new technologies. Perhaps most importantly, resource management must also include a plan for survival in a flat-funding environment. Lastly, creative and disciplined contract management will be essential to effecting the closure of any DOE site. Fluor Fernald, together with …
Date: February 25, 2001
Creator: Bradburne, John & Patton, Tisha C.
System: The UNT Digital Library
Achieving High Flux Amplification in a Gun-driven, Flux-core Spheromak (open access)

Achieving High Flux Amplification in a Gun-driven, Flux-core Spheromak

None
Date: February 20, 2007
Creator: Hooper, E. B.; Hill, D. N.; McLean, H. S.; Romero-Talam?s, C. A. & Wood, R. D.
System: The UNT Digital Library
Acoustic emission techniques in nondestructive testing (open access)

Acoustic emission techniques in nondestructive testing

None
Date: February 1, 1973
Creator: Liptai, R. G. & Tatro, C. A.
System: The UNT Digital Library
ACP/R3000 processors in data acquisition systems (open access)

ACP/R3000 processors in data acquisition systems

We describe ACP/R3000 processor based data acquisition systems for high energy physics. This VME bus compatible processor board, with a computational power equivalent to 15 VAX 11/780s or better, contains 8 Mb of memory for event buffering and has a high speed secondary bus that allows data gathering from front end electronics. 2 refs., 3 figs.
Date: February 1, 1989
Creator: Deppe, J.; Areti, H.; Atac, R.; Biel, J.; Cook, A.; Edel, M. et al.
System: The UNT Digital Library
Acquisition and preparation of specimens of rock for large-scale testing (open access)

Acquisition and preparation of specimens of rock for large-scale testing

The techniques used for acquisition and preparation of large specimens of rock for laboratory testing depend upon the location of the specimen, the type of rock and the equipment available at the sampling site. Examples are presented to illustrate sampling and preparation techniques used for two large cylindrical samples of granitic material, one pervasively fractured and one containing a single fracture.
Date: February 1, 1981
Creator: Watkins, D.J.
System: The UNT Digital Library
Acquisition and processing of multiparametric information from apixelmatrix (open access)

Acquisition and processing of multiparametric information from apixelmatrix

This paper addresses the design of a system intended to readout multiparametric information from a matrix of pixels. The system presented here acquires the charge associated with the signal and provides a timing information from each pixel. Although it lends itself to a broad range of time-correlated imaging situations involving any kind of pixel matrices, the design constraints assumed here are particularly tailored to the application with pixels that sense the output charge distribution from a Micro Channel Plate (MCP). The combination of a microchannel plate and a pixel matrix is an extremely versatile detector and the readout system must be able to fully exploit the intrinsically high position resolution and time accuracy featured by the MCP. The behavior of the readout system described in this paper is based upon advanced concepts to meet the above application requirements and is believed to provide a significant functional improvement over the conventional pixel systems.
Date: February 1, 2001
Creator: Manfredi, P.F.; Millaud, J.E. & Sushkov, V.V.
System: The UNT Digital Library
Actinic defect counting statistics over 1 cm2 area of EUVL mask blank (open access)

Actinic defect counting statistics over 1 cm2 area of EUVL mask blank

As a continuation of comparison experiments between EUV inspection and visible inspection of defects on EUVL mask blanks, we report on the result of an experiment where the EUV defect inspection tool is used to perform at-wavelength defect counting over 1 cm{sup 2} of EUVL mask blank. Initial EUV inspection found five defects over the scanned area and the subsequent optical scattering inspection was able to detect all of the five defects. Therefore, if there are any defects that are only detectable by EUV inspection, the density is lower than the order of unity per cm2. An upgrade path to substantially increase the overall throughput of the EUV inspection system is also identified in the manuscript.
Date: February 18, 2000
Creator: Jeong, Seongtae; Lai, Chih-Wei; Rekawa, Seno; Walton, Chris W. & Bokor, Jeffrey
System: The UNT Digital Library
Actinide Thermodynamics at Higher Temperatures (open access)

Actinide Thermodynamics at Higher Temperatures

This report is about the Actinide Thermodynamics at Higher Temperatures
Date: February 9, 2005
Creator: Friese, J.
System: The UNT Digital Library
Action-Oriented Benchmarking: Concepts and Tools (open access)

Action-Oriented Benchmarking: Concepts and Tools

Most energy benchmarking tools provide static feedback on how one building compares to a larger set of loosely similar buildings, without providing information at the end-use level or on what can be done to reduce consumption, cost, or emissions. In this article--Part 1 of a two-part series--we describe an 'action-oriented benchmarking' approach, which extends whole-building energy benchmarking to include analysis of system and component energy use metrics and features. Action-oriented benchmarking thereby allows users to generate more meaningful metrics and to identify, screen and prioritize potential efficiency improvements. This opportunity assessment process can then be used to inform and optimize a full-scale audit or commissioning process. We introduce a new web-based action-oriented benchmarking system and associated software tool-EnergyIQ. The benchmarking methods, visualizations, and user interface design are informed by an end-user needs assessment survey and best-practice guidelines from ASHRAE.
Date: February 13, 2008
Creator: Commission, California Energy; Mathew, Paul; Mills, Evan; Mathew, Paul; Piette, Mary Ann; Bourassa, Norman et al.
System: The UNT Digital Library
Action-Oriented Benchmarking: Using the CEUS Database to Benchmark Commercial Buildings in California (open access)

Action-Oriented Benchmarking: Using the CEUS Database to Benchmark Commercial Buildings in California

The 2006 Commercial End Use Survey (CEUS) database developed by the California Energy Commission is a far richer source of energy end-use data for non-residential buildings than has previously been available and opens the possibility of creating new and more powerful energy benchmarking processes and tools. In this article--Part 2 of a two-part series--we describe the methodology and selected results from an action-oriented benchmarking approach using the new CEUS database. This approach goes beyond whole-building energy benchmarking to more advanced end-use and component-level benchmarking that enables users to identify and prioritize specific energy efficiency opportunities - an improvement on benchmarking tools typically in use today.
Date: February 1, 2008
Creator: Mathew, Paul; Mills, Evan; Bourassa, Norman & Brook, Martha
System: The UNT Digital Library
Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction (open access)

Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction

The activation energy of a high melting temperature sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the High Pressure Spark Plasma Sintering (HPSPS) technique to 300 and 400 C to produce pellets with dimensions of 5 mm diameter by 1.5 mm height. A custom built ignition setup was developed to measure ignition temperatures at high heating rates (500-2000 C {center_dot} min{sup -1}). Such heating rates were required in order to ignite the thermite composite. Unlike the 400 C samples, results show that the samples consolidated to 300 C undergo an abrupt change in temperature response prior to ignition. This change in temperature response has been attributed to the crystallization of the amorphous WO{sub 3} in the SG derived Ta-WO{sub 3} thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO{sub 3} thermite ranged from approximately 465-670 C. The activation energy of the SG derived Ta-WO{sup 3} thermite composite consolidated to 300 and 400 C were determined to be 37.787 {+-} 1.58 kJ {center_dot} mol{sup -1} and 57.381 {+-} 2.26 kJ {center_dot} mol{sup -1}, respectively.
Date: February 25, 2010
Creator: Cervantes, O.; Kuntz, J.; Gash, A. & Munir, Z.
System: The UNT Digital Library
ACTIVE CAPPING TECHNOLOGY - NEW APPROACHES FOR IN SITU REMEDIATION OF CONTAMINATED SEDIMENTS (open access)

ACTIVE CAPPING TECHNOLOGY - NEW APPROACHES FOR IN SITU REMEDIATION OF CONTAMINATED SEDIMENTS

This study evaluated pilot-scale active caps composed of apatite, organoclay, biopolymers, and sand for the remediation of metal-contaminated sediments. The active caps were constructed in Steel Creek, at the Savannah River Site near Aiken, South Carolina. Monitoring was conducted for 12 months. Effectiveness of the caps was based on an evaluation of contaminant bioavailability, resistance to erosion, and impacts on benthic organisms. Active caps lowered metal bioavailability in the sediment during the one-year test period. Biopolymers reduced sediment suspension during cap construction, increased the pool of carbon, and lowered the release of metals. This field validation showed that active caps can effectively treat contaminants by changing their speciation, and that caps can be constructed to include more than one type of amendment to achieve multiple goals.
Date: February 13, 2012
Creator: Knox, A.; Paller, M. & Roberts, J.
System: The UNT Digital Library
Active neutron interrogation for verification of storage of weapons components at the Oak Ridge Y-12 Plant (open access)

Active neutron interrogation for verification of storage of weapons components at the Oak Ridge Y-12 Plant

A nuclear weapons identification system (NWIS), under development since 1984 at the Oak Ridge Y-12 Plant and presently in use there, uses active neutron interrogation with low-intensity {sup 252}Cf sources in ionization chambers to provide a timed source of fission neutrons from the spontaneous fission of {sup 252}Cf. To date, measurements have been performed on {approximately}15 different weapons systems in a variety of configurations both in and out of containers. Those systems included pits and fully assembled systems ready for deployment at the Pantex Plant in Amarillo, Texas, and weapons components at the Oak Ridge Y-12 Plant. These measurements have shown that NWIS can identify nuclear weapons and/or components; nuclear weapons/components can be distinguished from mockups where fissile material has been replaced by nonfissile material; omissions of small amounts (4%) of fissile material can be detected; changes in internal configurations can be determined; trainer parts can be identified as was demonstrated by verification of 512 containers with B33 components at the Y-12 Plant (as many as 32 in one 8-hour shift); and nonfissile components can be identified. The current NWIS activities at the Oak Ridge Y-12 Plant include: (1) further development of the system for more portability and lower power …
Date: February 23, 1998
Creator: Mihalczo, J. T.; Valentine, T. E.; Mattingly, J. K.; Mullens, J. A. & Hughes, S. S.
System: The UNT Digital Library
Active sensors for health monitoring of aging aerospace structures (open access)

Active sensors for health monitoring of aging aerospace structures

A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens …
Date: February 29, 2000
Creator: Giurgiutiu, Victor; Redmond, James M.; Roach, Dennis & Rackow, Kirk A.
System: The UNT Digital Library
Adaptation of a neutron diffraction detector to coded aperture imaging (open access)

Adaptation of a neutron diffraction detector to coded aperture imaging

A coded aperture neutron imaging system developed at Brookhaven National Laboratory (BNL) has demonstrated that it is possible to record not only a flux of thermal neutrons at some position, but also the directions from whence they came. This realization of an idea which defied the conventional wisdom has provided a device which has never before been available to the nuclear physics community. A number of potential applications have been explored, including (1) counting warheads on a bus or in a storage area, (2) investigating inhomogeneities in drums of Pu-containing waste to facilitate non-destructive assays, (3) monitoring of vaults containing accountable materials, (4) detection of buried land mines, and (5) locating solid deposits of nuclear material held up in gaseous diffusion plants.
Date: February 1, 1997
Creator: Vanier, P. E. & Forman, L.
System: The UNT Digital Library
Adaptations of the Purge Water Management System for Long-Term Groundwater Monitoring at Savannah River Site, South Carolina (final) (open access)

Adaptations of the Purge Water Management System for Long-Term Groundwater Monitoring at Savannah River Site, South Carolina (final)

To monitor the groundwater contamination and the effectiveness of remedial actions, over a thousand monitoring wells are in active operation (i.e., require quarterly or semi-annual sampling) at SRS. Most wells are expected to continue in operation for another 20 to 40 more years. Required sample volumes can range from a less than a liter to 10 liters. To support the long-term groundwater monitoring requirements of these wells, SRS actively seeks technologies that can maximize data acquisition and minimize costs. To meet this end, SRS has implemented the Purge Water Management System (PWMS). The key attributes of this system lie in its ability to reduce or eliminate the generation of purged groundwater, which is costly in terms of the time and management.
Date: February 10, 2004
Creator: Schiefer, E
System: The UNT Digital Library
Adapting high-resolution speckle imaging to moving targets and platforms (open access)

Adapting high-resolution speckle imaging to moving targets and platforms

High-resolution surveillance imaging with apertures greater than a few inches over horizontal or slant paths at optical or infrared wavelengths will typically be limited by atmospheric aberrations. With static targets and static platforms, we have previously demonstrated near-diffraction limited imaging of various targets including personnel and vehicles over horizontal and slant paths ranging from less than a kilometer to many tens of kilometers using adaptations to bispectral speckle imaging techniques. Nominally, these image processing methods require the target to be static with respect to its background during the data acquisition since multiple frames are required. To obtain a sufficient number of frames and also to allow the atmosphere to decorrelate between frames, data acquisition times on the order of one second are needed. Modifications to the original imaging algorithm will be needed to deal with situations where there is relative target to background motion. In this paper, we present an extension of these imaging techniques to accommodate mobile platforms and moving targets.
Date: February 5, 2004
Creator: Carrano, C J & Brase, J M
System: The UNT Digital Library