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Behavior and evaluation of an existing underground structure subjected to impulsive loads from an internal explosion
An explosion is the result of a rapid chemical reaction which generates transient air pressure waves called blast waves. There has been much research on the processes of blast wave formation, propagation of blast waves, and quantification of the incident and reflected blast overpressures. The magnitude of blast overpressure, in a partially vented environment, is mainly a function of the type and quantity of detonating material, the amount of available venting, and the orientation and configuration of the reflecting surfaces. In addition to blast overpressure, an explosion can also generate high energy missiles (such as fragments), shock loads, and rapid rise of temperature in the confined space. This study concentrates on the effects of blast overpressure on a 40 feet diameter reinforced concrete cylinder with a hemispherical dome roof, supported on a 3 feet thick reinforced concrete pad, and buried under a minimum of 15 feet of soil used for radiation shielding at the top of the dome. The scope of this study is to determine whether the structure can withstand the blast overpressure generated by the postulated explosion without exceeding allowable design criteria.
Date:
December 1, 1997
Creator:
Keller, M. D. & Khan, P. K.
Object Type:
Article
System:
The UNT Digital Library
Biophysical and biological factors determining the ability to achieve long-term cryobiological preservation
The BESTCapsule will maintain appropriate biological specimens for decades or centuries at cryogenic temperatures in the living state. Maintenance at temperatures below {approximately} {minus}140 C is not a problem. No ordinary chemical reactions in aqueous solutions can occur. The only source of damage will be the slow accumulation of physical damage to DNA from background ionizing radiation. But this source of damage should not become serious in less than a millennium. Rather, the main problem in cryopreservation is to devise procedures for cooling the biological specimens to {minus}196 C and returning them to normal temperatures without inflicting lethal injury. Regardless of the cell type, there are certain encompassing biophysical factors and constraints that determine whether they will survive or die during freezing and thawing. Superimposed on these may be special biological factors that apply to specific cell types. This paper will emphasize the former and give illustrative examples of the latter.
Date:
December 1, 1997
Creator:
Mazur, P.
Object Type:
Article
System:
The UNT Digital Library
Boron-enhanced-diffusion of boron: The limiting factor for ultra-shallow junctions
Reducing implant energy is an effective way to eliminate transient enhanced diffusion (TED) due to excess interstitials from the implant. It is shown that TED from a fixed Si dose implanted at energies from 0.5 to 20 keV into boron doping-superlattices decreases linearly with decreasing Si ion range, virtually disappearing at sub-keV energies. However, for sub-keV B implants diffusion remains enhanced and x{sub j} is limited to {ge} 100 nm at 1,050 C. The authors term this enhancement, which arises in the presence of B atomic concentrations at the surface of {approx} 6%, Boron-Enhanced-Diffusion (BED).
Date:
December 1, 1997
Creator:
Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C. et al.
Object Type:
Article
System:
The UNT Digital Library
Bremsstrahlung and pair creation: Suppression mechanisms and how they affect EHE air showers
Most calculations of air shower development have been based on the Bethe-Heitler cross sections for bremsstrahlung and pair production. However, for energetic enough particles, a number of different external factors can reduce these cross sections drastically, slowing shower development and lengthening the showers. Four mechanisms that can suppress bremsstrahlung and pair production cross sections are discussed, and their effect on extremely high energy air showers considered. Besides lengthening the showers, these mechanisms greatly increase the importance of fluctuations in shower development, and can increase the angular spreading of showers.
Date:
December 1, 1997
Creator:
Klein, S.R.
Object Type:
Article
System:
The UNT Digital Library
Bridgman growth and characterization of bulk single crystals of Ga{sub 1{minus}x}In{sub x}Sb for thermophotovoltaic applications
Thermophotovoltaic generation of electricity is attracting renewed attention due to recent advances in low bandgap (0.5--0.7 eV) III-V semiconductors. The use of mixed pseudo-binary compounds allows for the tailoring of the lattice parameter and the bandgap of the material. Conventional deposition techniques (i.e., epitaxy) for producing such ternary or quaternary materials are typically slow and expensive. Production of bulk single crystals of ternary materials, for example Ga{sub 1{minus}x}In{sub x}Sb, is expected to dramatically reduce such material costs. Bulk single crystals of Ga{sub 1{minus}x}In{sub x}Sb have been prepared using a Bridgman technique in a two-zone furnace. These crystals are 19 mm in diameter by approximately 50 mm long and were produced using seeds of the same diameter. The effects of growth rate and starting materials on the composition and quality of these crystals will be discussed and compared with other attempts to produce single crystals of this material.
Date:
December 1, 1997
Creator:
Boyer, J. R. & Haines, W. T.
Object Type:
Report
System:
The UNT Digital Library
Calculated lattice relaxation in Pu-Ga alloys
Hellman-Feynman forces on atoms surrounding the gallium site in a Pu{sub 31}Ga supercell are calculated with the full-potential LMTO method in the local density approximation. These forces are minimized by adjusting atomic positions using an iterative Broyden scheme. At equilibrium the nearest-neighbor shell of plutonium atoms relaxes inward by 1.04% of the initial theoretical bond length (2.86 {angstrom}). A similar calculation on a Pu{sub 32} supercell shows no relaxation.
Date:
December 1, 1997
Creator:
Becker, J. D.; Wills, J. M.; Cox, L. & Cooper, B. R.
Object Type:
Article
System:
The UNT Digital Library
Calculation of discrete fracture flow paths in dual-continuum models
Movement of water through fractures plays an important role in performance assessments of the potential high-level nuclear waste repository at Yucca Mountain, Nevada. The magnitude and frequency of water flowing through individual fractures impacts predictions of the near-field environment and waste-package corrosion. Discrete fracture flow paths, referred to as ``weeps``, have been derived from dual continuum models of fracture flow. The required parameters include the geometric fracture spacing, an assumed width of each weep, and a scaling factor that accounts for reduced flow between fracture and matrix elements in dual continuum models. The formulation provides a convenient means to determine discrete weep spacing and flow rates that are mathematically consistent with the dual continuum model. Specific applications and examples related to seepage into drifts are also discussed.
Date:
December 1, 1997
Creator:
Ho, C. K. & Wilson, M. L.
Object Type:
Article
System:
The UNT Digital Library
Calibration and Evaluation of Blackbeard Time Tagging Capability
During November and December of 1996, the Los Alamos Portable Pulser (LAPP) facility was used to evaluate the accuracy of time tags produced by the Blackbeard instrument, a payload on the ALEXIS (Array of Low Energy X-ray Imaging Sensors) satellite. Over a two-month period, LAPP transmitted 65 broadband electromagnetic pulses to Blackbeard during satellite passes over North America. Of the 65 pulses transmitted, 31 were successfully received by Blackbeard. Ground-based diagnostics and a timing system disciplined by GPS allowed precise determinations of LAPP firing times to be made. Knowledge of the range to ALEXIS for each of the pulser shots allowed them to determine pulse propagation delays. The firing times were used in conjunction with propagation delays to compute estimated times of arrival (ETOAs) for pulses reaching Blackbeard. ETOAs were compared to Blackbeard reported times of arrival (RTOAs), which were computed from information returned by Blackbeard using an algorithm presented in this paper. For the 31 pulser shots received by Blackbeard, the mean difference between ETOA and RTOA was 1.97 milliseconds, with RTOAs occurring later than ETOAs. The standard deviation of the difference was 0.43 milliseconds. As a result of the study, the algorithm used for accurate Blackbeard time tat …
Date:
December 1, 1997
Creator:
Smith, David A.; DeLapp, Dorothea M.; Holden, Daniel N.; Stelzer, Gary L. & Klingner, Phillip L.
Object Type:
Article
System:
The UNT Digital Library
Calibration issues for neutron diagnostics
The performance of diagnostic systems are limited by their weakest constituents, including their calibration issues. Neutron diagnostics are notorious for problems encountered while determining their absolute calibrations, due mainly to the nature of the neutron transport problem. In order to facilitate the determination of an accurate and precise calibration, the diagnostic design should be such as to minimize the scattered neutron flux. ITER will use a comprehensive set of neutron diagnostics--comprising radial and vertical neutron cameras, neutron spectrometers, a neutron activation system and internal and external fission chambers--to provide accurate measurements of fusion power and power densities as a function of time. The calibration of such an important diagnostic system merits careful consideration. Some thoughts have already been given to this subject during the conceptual design phase in relation to the time-integrated neutron activation and time-dependent neutron yield monitors. However, no overall calibration strategy has been worked out so far. This paper represents a first attempt to address this vital issue. Experience gained from present large tokamaks (JET, TFTR and JT60U) and proposals for ITER are reviewed. The need to use a 14-MeV neutron generator as opposed to radioactive sources for in-situ calibration of D-T diagnostics will be stressed. It …
Date:
December 1, 1997
Creator:
Sadler, G. J.; Adams, J. M. & Barnes, C. W.
Object Type:
Report
System:
The UNT Digital Library
Canyon dissolution of sand, slag, and crucible residues
An alternative to the FB-Line scrap recovery dissolver was desired for the dissolution of sand, slag, and crucible (SS{ampersand}C) residues from the plutonium reduction process due to the potential generation of hydrogen gas concentrations above the lower flammability limit. To address this concern, a flowsheet was developed for the F-Canyon dissolvers. The dissolvers are continually purged with nominally 33 SCFM of air; therefore the generation of flammable gas concentrations should not be a concern. Following removal of crucible fragments, small batches of the remaining sand fines or slag chunks containing less than approximately 350 grams of plutonium can be dissolved using the center insert in each of the four annular dissolver ports to address nuclear criticality safety concerns. Complete dissolution of the sand fines and slag chunks was achieved in laboratory experiments by heating between 75 and 85 degrees Celsius in a 9.3M nitric acid/0.013M (hydrogen) fluoride solution. Under these conditions, the sand and slag samples dissolved between 1 and 3 hours. Complete dissolution of plutonium and calcium fluorides in the slag required adjusting the dissolver solution to 7.5 wt% aluminum nitrate nonahydrate (ANN). Once ANN was added to a dissolver solution, further dissolution of any plutonium oxide (PuO2) in …
Date:
December 1, 1997
Creator:
Rudisill, Tracy S.; Gray, John H.; Karraker, David G. & Chandler, Gregory T.
Object Type:
Report
System:
The UNT Digital Library
Capability of environmental sampling to detect undeclared cask openings
The goal of this study is to determine the signatures that would allow monitors to detect diversion of nuclear fuel (by a diverter) from a storage area such as a geological repository. Due to the complexity of operations surrounding disposal of spent nuclear fuel in a geologic repository, there are several places that a diversion of fuel could take place. After the canister that contains the fuel rods is breached, the diverter would require a hot cell to process or repackage the fuel. A reference repository and possible diversion scenarios are discussed. When a canister is breached, or during reprocessing to extract nuclear weapons material (primarily Pu), several important isotopes or signatures including tritium, {sup 85}Kr, and {sup 129}I are released to the surrounding environment and have the potential for analysis. Estimates of release concentrations of the key signatures from the repository under a hypothetical diversion scenario are presented and discussed. Gas analysis data collected from above-ground storage casks at Idaho National Engineering and Environmental Laboratory (INEEL) Test Area North (TAN) are included and discussed in the report. In addition, LANL participated in gas sampling of one TAN cask, the Castor V/21, in July 1997. Results of xenon analysis from …
Date:
December 1, 1997
Creator:
Beckstead, L. W.; Efurd, D. W.; Hemberger, P. H.; Abhold, M. E. & Eccleston, G. W.
Object Type:
Article
System:
The UNT Digital Library
Carbon composite for a PEM fuel cell bipolar plate
The current major cost component for proton exchange membrane fuel cells is bipolar plate. An option being explored for replacing the current, nominal machined graphite component is a molded carbon fiber material. One face and the volume of the component will be left porous, while the opposite surface and sides are hermetically sealed via chemical vapor infiltration of carbon. This paper will address initial work on the concept.
Date:
December 1, 1997
Creator:
Besmann, T.M.; Klett, J.W. & Burchell, T.D.
Object Type:
Article
System:
The UNT Digital Library
Carbon stripper foils used in the Los Alamos PSR
Carbon stripper foils produced by the modified controlled ACDC arc discharge method (mCADAD) at the Institute for Nuclear Study have been tested and used for high current 800-MeV beam production in the Proton Storage Ring (PSR) since 1993. Two foils approximately 110 {mu}g/cm{sup 2} each are sandwiched together to produce an equivalent 220 {mu}g/cm{sup 2} foil. The foil sandwitch is supported by 4-5 {mu}m diameter carbon filters attached to an aluminum frame. These foils have survived as long as five months during PSR normal beam production of near 70 {mu}A average current on target. Typical life-times of other foils vary from seven to fourteen days with lower on-target average current. Beam loss data also indicate that these foils have slower shrinkage rates than standard foils. Equipment has been assembled and used to produce foils by the mCADAD method at Los Alamos. These foils will be tested during 1997 operation.
Date:
December 1, 1997
Creator:
Borden, M. J.; Plum, M. A. & Sugai, I.
Object Type:
Article
System:
The UNT Digital Library
Cat's Claw (Archer City, Tex.), Vol. 52, No. 3, Ed. 1 Monday, December 1, 1997
Monthly student newspaper from Archer City High School in Archer City, Texas that includes news and information of interest to students along with advertising.
Date:
December 1, 1997
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Centrally managed name resolution schemes for EPICS
The Experimental Physics and Industrial Control System (EPICS) uses a broadcast method to locate resources and controls distributed across control servers. There are many advantages offered by using a centrally managed name resolution method, in which resources are located using a repository. The suitability of DCE Directory Service as a name resolution method is explored, and results from a study involving DCE are discussed. An alternative nameserver method developed and in use at the Thomas Jefferson national Accelerator Facility (Jefferson Lab) is described and results of integrating this new method with existing EPICS utilities presented. The various methods discussed in the paper are compared.
Date:
December 1, 1997
Creator:
Jun, D.; Bryan, D. & Watson, W.
Object Type:
Article
System:
The UNT Digital Library
Cerium heavy-fermion compounds near their T = 0 magnetic-non-magnetic boundary
Measurements of the temperature-dependent specific heat and thermal expansion coefficient near a T = 0 magnetic-non-magnetic boundary, accessed in CeRh{sub 2}Si{sub 2} by application of pressure and in CeRh{sub 2{minus}x}Ru{sub x}Si{sub 2} at ambient pressure by chemical substitution, emphasize the role of disorder in producing non-Fermi-liquid behavior. Interestingly, superconductivity also develops near this boundary in some crystallographically-ordered Ce-based heavy-fermion compounds.
Date:
December 1, 1997
Creator:
Thompson, J. D.; Hundley, M. F.; Movshovich, R.; Sarrao, J. L.; Graf, T.; Uwatoko, Y. et al.
Object Type:
Report
System:
The UNT Digital Library
Chain modeling for life cycle systems engineering
Throughout Sandia`s history, products have been represented by drawings. Solid modeling systems have recently replaced drawings as the preferred means for representing product geometry. These systems are used for product visualization, engineering analysis and manufacturing planning. Unfortunately, solid modeling technology is inadequate for life cycle systems engineering, which requires maintenance of technical history, efficient management of geometric and non-geometric data, and explicit representation of engineering and manufacturing characteristics. Such information is not part of the mathematical foundation of solid modeling. The current state-of-the-art in life cycle engineering is comprised of painstakingly created special purpose tools, which often are incompatible. New research on {open_quotes}chain modeling{close_quotes} provides a method of chaining the functionality of a part to the geometric representation. Chain modeling extends classical solid modeling to include physical, manufacturing, and procedural information required for life cycle engineering. In addition, chain modeling promises to provide the missing theoretical basis for Sandia`s parent/child product realization paradigm. In chain modeling, artifacts and systems are characterized in terms of their combinatorial properties: cell complexes, chains, and their operators. This approach is firmly rooted in algebraic topology and is a natural extension of current technology. The potential benefits of this approach include explicit hierarchical and combinatorial …
Date:
December 1, 1997
Creator:
Rivera, J.J. & Shapiro, V.
Object Type:
Report
System:
The UNT Digital Library
Characterization analysis database system (CADS): A system overview
The CADS database is a standardized, quality-assured, and configuration-controlled data management system developed to assist in the task of characterizing the DOE surplus HEU material. Characterization of the surplus HEU inventory includes identifying the specific material; gathering existing data about the inventory; defining the processing steps that may be necessary to prepare the material for transfer to a blending site; and, ultimately, developing a range of the preliminary cost estimates for those processing steps. Characterization focuses on producing commercial reactor fuel as the final step in material disposition. Based on the project analysis results, the final determination will be made as to the viability of the disposition path for each particular item of HEU. The purpose of this document is to provide an informational overview of the CADS database, its evolution, and its current capabilities. This document describes the purpose of CADS, the system requirements it fulfills, the database structure, and the operational guidelines of the system.
Date:
December 1, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Characterization of the Radon Source in North-Central Florida. Final Report Part 1 -- Final Project Report; Final Report Part 2 -- Technical Report
This report contains two separate parts: Characterization of the Radon Source in North-Central Florida (final report part 1 -- final project report); and Characterization of the Radon Source in North-Central Florida (technical report). The objectives were to characterize the radon 222 source in a region having a demonstrated elevated indoor radon potential and having geology, lithology, and climate that are different from those in other regions of the U.S. where radon is being studied. Radon availability and transport in this region were described. Approaches for predicting the radon potential of lands in this region were developed.
Date:
December 1, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Chemical and radiochemical constituents in water from wells in the vicinity of the Naval Reactors Facility, Idaho National Engineering Laboratory, Idaho, 1994--95
The US Geological Survey, in response to a request from the US Department of Energy`s Pittsburgh Naval Reactors Office, Idaho Branch Office, sampled water from 14 wells during 1994--95 as part of a long-term project to monitor water quality of the Snake River Plain aquifer in the vicinity of the Naval Reactors Facility, Idaho National Engineering Laboratory, Idaho. Water samples were analyzed for naturally occurring constituents and manmade contaminants. A total of 111 samples were collected from 10 monitoring wells and 4 production wells. Twelve quality-assurance samples also were collected and analyzed; 1 was a blank sample and 11 were replicate samples. The blank sample contained concentrations of one inorganic constituent, one organic constituent, and five radioactive constituents that were greater than the reporting levels. Concentrations of other constituents in the blank sample were less than their respective reporting levels. The 11 replicate samples and their respective primary samples generated 293 pairs of analytical results for a variety of chemical and radiochemical constituents. Of the 293 data pairs, 258 were statistically equivalent at the 95-percent confidence level; about 88 percent of the analytical results were in agreement.
Date:
December 1, 1997
Creator:
Bartholomay, R.C.; Knobel, L.L. & Tucker, B.J.
Object Type:
Report
System:
The UNT Digital Library
Chemical compatibility screening test results
A program for evaluating packaging components that may be used in transporting mixed-waste forms has been developed and the first phase has been completed. This effort involved the screening of ten plastic materials in four simulant mixed-waste types. These plastics were butadiene-acrylonitrile copolymer rubber, cross-linked polyethylene (XLPE), epichlorohydrin rubber, ethylene-propylene rubber (EPDM), fluorocarbon (Viton or Kel-F), polytetrafluoroethylene, high-density polyethylene (HDPE), isobutylene-isoprene copolymer rubber (butyl), polypropylene, and styrene-butadiene rubber (SBR). The selected simulant mixed wastes were (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. The testing protocol involved exposing the respective materials to 286,000 rads of gamma radiation followed by 14-day exposures to the waste types at 60{degrees}C. The seal materials were tested using vapor transport rate (VTR) measurements while the liner materials were tested using specific gravity as a metric. For these tests, a screening criterion of 0.9 g/hr/m{sup 2} for VTR and a specific gravity change of 10% was used. Based on this work, it was concluded that while all seal materials passed exposure to the aqueous simulant mixed waste, EPDM and SBR had the lowest VTRs. In the …
Date:
December 1, 1997
Creator:
Nigrey, P. J. & Dickens, T. G.
Object Type:
Report
System:
The UNT Digital Library
Chemical kinetics of Estane aging in PBX
The Plastic-Bonded Explosive PBX 9501 is about 95% HMX, 2.5% Estane 5703, 2.5% nitroplasticizer (NP), and 0.1% stabilizer by weight. The NP, BDNPA/F, is a eutectic mixture of bis(2,2-dinitropropyl) acetal and bis(2,2-dinitropropyl)formal. The stabilizer is diphenylamine (DPA) or Irganox 1010. The Estane, a polyester-polyurethane, slowly degrades with time. Knowledge of the effect of the Estane aging on the mechanical properties of the PBX 9501 is required to predict with confidence the useful lifetime of the explosive with respect to safety and reliability. A detailed master equation model of the chemical mechanisms and kinetics of the aging of Estane 5703 in PBX 9501 is being developed. Its output will be used as input into other models being developed to calculate the changes in the mechanical properties of the PBX.
Date:
December 1, 1997
Creator:
Pack, R. T.; Hanson, D. E. & Redondo, A.
Object Type:
Article
System:
The UNT Digital Library
Chemical pathways for the formation of ammonia in Hanford wastes
This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important).
Date:
December 1, 1997
Creator:
Stock, L. M. & Pederson, L. R.
Object Type:
Report
System:
The UNT Digital Library
Chemistry & Materials Science progress report summary of selected research and development topics, FY97
This report contains summaries of research performed in the Chemistry and Materials Science division. Topics include Metals and Ceramics, High Explosives, Organic Synthesis, Instrument Development, and other topics.
Date:
December 1, 1997
Creator:
Newkirk, L.
Object Type:
Report
System:
The UNT Digital Library