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Fracture toughness of anisotropic graphites

Description: Fracture toughness measurements have been made at 0, 30, 45, 60, and 90/sup 0/ from the extrusion axis on a reasonably anisotropic graphite, grade AGOT. It was found that the fracture toughness did not vary appreciably with orientation. An observed variation in strength was found to be the result of defect orientation.
Date: January 1, 1985
Creator: Kennedy, C.R. & Kehne, M.T.
Partner: UNT Libraries Government Documents Department

Comparative analysis of hydrogen fire and explosion incidents. Quarterly report No. 1, September 1, 1977--November 30, 1977

Description: A hydrogen accident data base covering industrial and other forms of hydrogen use is being developed. Ten different sources of hydrogen accident reports have contributed 168 reports for the period 1971-1976 and 402 reports for the years prior to 1971. Additional data are being sought through a survey of major hydrogen consuming industries. National gas consumption and accident data have also been collected to serve as a basis for comparison with the hydrogen accident data. During the next quarter, a computer data entry and retrieval program will be written to sort and tabulate the hydrogen accident data.
Date: December 1, 1977
Creator: Zalosh, R.G.
Partner: UNT Libraries Government Documents Department

Multistage metal hydride compressor

Description: Metal hydride compressors can compress hydrogen to high pressures without using mechanical moving parts. They are particularly suited for tritium applications because they require minimal maintenance. A three-stage metal hydride compressor which can compress hydrogen from 14.7 to 20,000 psia has been demonstrated. The design principle and experimental results are presented.
Date: January 1, 1986
Creator: Heung, L.K.
Partner: UNT Libraries Government Documents Department

Carbon in high-purity germanium

Description: Using /sup 14/C-spiked pyrolytic graphite-coated quartz crucibles for the growth of nine ultra-pure germanium single crystals, we have determined the carbon content and distribution in these crystals. Using autoradiography, we observe a rapidly decreasing carbon cluster concentration in successively grown crystals. Nuclear radiation detectors made from the crystals measure the betas from the internally decaying /sup 14/C nuclei with close to 100% efficiency. An average value for the total carbon concentration (/sup 14/C + /sup 12/C) is approx. 2 x 10/sup 14/ cm/sup -3/, a value substantially larger than expected from earlier metallurgical studies. Contrary to the most recent measurement, we find the shape of the beta spectrum to agree very well with the statistical shape predicted for allowed transitions.
Date: October 1, 1981
Creator: Haller, E.E.; Hansen, W.L.; Luke, P.; McMurray, R. & Jarrett, B.
Partner: UNT Libraries Government Documents Department

Membrane oxygen enrichment cost and application evaluation

Description: A separation process, similar to the reverse osmosis membrane process for the desalination of water, can be used for the separation and enrichment of multi-component gas streams. The development of new processing methods and modular packing systems together with advanced commercialization of desalination systems now makes similar processes for gas separation appear feasible and economical. Composite membranes have been developed that are both thin enough to provide a large gas flow and strong enough to withstand the driving pressure of the incoming gas. This is done by depositing a polymer on the finely porous surface of a fabric-reinforced supporting membrane. The resulting material is then formed into a spiral-wound element that provides a large amount of membrane area in a small volume. Laboratory experiments using gas separation membranes by Fluid Systems Division of UOP and by General Electric Company have established the technical feasibility of using such membranes to produce oxygen-enriched air. A preliminary analysis of membrane oxygen enrichment economics was prepared by the Fluid System Division of UOP which shows that oxygen enrichment could be profitable for combustion systems up to 100 tons of oxygen per day. A supporting economic study made by Econergy Associates reaffirms the positive economics potential for a 1000-ton/d, 30% O/sub 2/ enrichment plant.
Date: March 1, 1979
Creator: Fischer, J. & Burnett, L.J.
Partner: UNT Libraries Government Documents Department

Description of a unique machine tool permitting achievement of < 15-A rms diamond-turned surfaces

Description: A new machine tool now in the final stages of development at the Pacific Northwest Laboratory uses a unique tool motion to produce diamond-turned surfaces of exceptionally high quality. The cutting tool is programmed to move in 4-nm increments along two axes: an X axis and an Omega axis. Exceptionally stiff and accurate control of the tool is possible with this Omega-X system. Copper surfaces of revolution have been produced with a 12.3-A rms surface finish and a contour accuracy of 75 nm. In conjunction with a unique, thermally stabilized air bearing spindle and machine calibration equipment, the Omega-X system permits a significant advance in the fabrication of optical-quality surfaces for use with the visible spectrum.
Date: January 1, 1980
Creator: Miller, D.M.; Hauver, G.H.; Culverhouse, J.N. & Greenwell, E.N.
Partner: UNT Libraries Government Documents Department

Recommendation of a triaxial failure theory for graphite

Description: An extensive literature search has been conducted on the application of triaxial failure theories to an anisotropic brittle solid. This study leads to the conclusion that the strength tensor theory of Tsai and Wu appears most promising for HTGR structural graphites. The reduction of this theory to model the transversely isotropic nature of HTGR structural graphites is presented. The extensions to the ongoing biaxial stress experimental program, needed to provide the additional data required to verify this theory, are defined.
Date: May 1, 1979
Creator: Tang, P.Y.
Partner: UNT Libraries Government Documents Department

Optical measurements on hydrogen at ultrahigh static pressures. Summary report for NRIP W233

Description: The results of a two-year New Research Initiatives Program (NRIP) aimed at developing apparatus and techniques for studying hydrogen and other gases under ultrahigh static pressure in diamond--anvil cells are summarized. The following goals were achieved: A facility was established in which precision optical measurements can be made; special diamond cells for use at low temperatures were built; procedures were devised for loading cells with gases at high density; preliminary visual, x-ray, and spectral studies on various gases at pressures up to 50 kbar were conducted; and having demonstrated the feasibility of NRIP, other sponsorship on a continuing basis was obtained.
Date: February 1, 1979
Creator: Mills, R.L. & Liebenberg, D.H.
Partner: UNT Libraries Government Documents Department

Low earth orbit molecular beam space simulation facility

Description: A brief synopsis of the low earth orbit (LEO) satellite environment is presented including neutral and ionic species. Two ground based atomic and molecular beam instruments are described which are capable of simulating the interaction of space craft surfaces with the LEO environment and detecting the results of these interactions. The first detects mass spectrometrically low level fluxes of reactively and nonreactively surface scattered species as a function of scattering angle and velocity while the second UHV molecular beam, laser induced fluorescence apparatus is capable of measuring chemiluminescence produced by either gas phase or gas-surface interactions. A number of proposed experiments will be described.
Date: January 1, 1984
Creator: Cross, J.B.
Partner: UNT Libraries Government Documents Department

Dependence of strength on particle size in graphite

Description: The strength to particle size relationship for specially fabricated graphites has been demonstrated and rationalized using fracture mechanics. In the past, similar studies have yielded empirical data using only commercially available material. Thus, experimental verification of these relationships has been difficult. However, the graphites of this study were fabricated by controlling the particle size ranges for a series of isotropic graphites. All graphites that were evaluated had a constant 1.85 g/cm/sup 3/ density. Thus, particle size was the only variable. This study also considered the particle size effect on other physical properties; coefficient of thermal expansion (CTE), electrical resistivity, fracture strain, and Young's modulus.
Date: June 8, 1980
Creator: Kennedy, E.P. & Kennedy, C.R.
Partner: UNT Libraries Government Documents Department

The new experimental areas oxygen monitor

Description: Because of the nature of the beamline requirements for oxygen monitoring equipment to operate ancillary equipment, such as exhaust fans, doors and cryogenic valves, and because of the well known problems of the oxygen sensors installed in high radiation areas, a new design for sensing the oxygen content of ambient air was needed. A new monitor system was designed to solve these problems and some others that compromised the reliability and the maintenance of the monitoring system. From the operating experience gained with the Accelerator Standard Oxygen Monitor System currently installed in many locations in the experimental area, from suggestions solicited from the Safety Group and from the Cryogenics Group, I designed a new Experimental Areas Standard Oxygen Monitor. Many suggestions were carefully considered and a design that incorporates most of them was constructed. I will summarize a list of the important improvements that will be of interest to the users of the system, and explain how these functions will make the oxygen system easier to live with. 2 figs.
Date: August 1, 1988
Creator: Schoo, D.
Partner: UNT Libraries Government Documents Department

Modified Weibull theory and stress-concentration factors of polycrystalline graphite

Description: Stress concentration factors (SCF) due to geometric discontinuities in graphite specimens are observed to be much less than the theoretical SCF in an elastic material. In fact, the experimental SCF is always less than two and sometimes even less than one. A four parameter Weibull theory which recognizes the grain size effect is found to give an adequate explanation of the above observed discrepancies.
Date: December 1, 1980
Creator: Ho, F.H.
Partner: UNT Libraries Government Documents Department

Neutron-induced prompt gamma activation analysis (PGAA) of metalsand non-metals in ocean floor geothermal vent-generated samples

Description: Neutron-induced prompt gamma activation analysis (PGAA) hasbeen used to analyze ocean floor geothermal vent-generated samples thatare composed of mixed metal sulfides, silicates, and aluminosilicates.The modern application of the PGAA technique is discussed, and elementalanalytical results are given for 25 elements observed in the samples. Theelemental analysis of the samples is consistent with the expectedmineralogical compositions, and very consistent results are obtained forcomparable samples. Special sensitivity to trace quantities of hydrogen,boron, cadmium, dysprosium, gadolinium, and samarium isdiscussed.
Date: December 5, 2002
Creator: Perry, D.L.; Firestone, R.B.; Molnar, G.L.; Revay, Zs.; Kasztovszky, Zs.; Gatti, R.C. et al.
Partner: UNT Libraries Government Documents Department


Description: As titanium, zirconium, and other of the high melting electropositive metals become more important, the problem of using suitable refractory materials for their casting becomes more important. This paper discusses the method of choosing and testing possible container materials. To make the discussion more specific, titanium is used as an example. As titanium melt at 2000 {+-} 10 K, it is immediately clear that one is restricted to refractory materials melting considerably above 2000 K. This greatly limits the possible materials that might be considered. The possibility of using any pure high melting element can be quickly eliminated as titanium reacts quite vigorously with non-metals such as carbon and due to its high boiling point and therefore high internal pressure, one can predict that it dissolves even the most refractory metals. Examination of phase diagrams confirms that even metals such as tantalum, tungsten, and rhenium would not be able to resist attack by titanium. One is thus limited to high melting compounds such as the oxides, sulfides, nitrides, carbides, silicides, and borides. The first consideration is that, if possible, one would use a compound which is thermodynamically stable in the presence of titanium metal at 2000 K. Titanium should not be able to react with the refractory to form a titanium compound. Thus all compounds less stable than the titanium compound which can exist in equilibrium with titanium metal are excluded.
Date: June 20, 1950
Creator: Brewer, Leo
Partner: UNT Libraries Government Documents Department


Description: Inorganic, titanate-based sorbents are tested with respect to adsorption of a variety of sorbates under weakly acidic conditions (pH 3). Specifically, monosodium titanate (MST) and amorphous peroxotitanate (APT) sorption characteristics are initially probed through a screening process consisting of a pair of mixed metal solutions containing a total of 29 sorbates including alkali metals, alkaline earth metals, transition metals, metalloids and nonmetals. MST and APT sorption characteristics are further analyzed individually with chromium(III) and cadmium(II) using a batch method at ambient laboratory temperature, varying concentrations of the sorbents and sorbates and contact times. Maximum sorbate loadings are obtained from the respective adsorption isotherms.
Date: November 11, 2009
Creator: Hobbs, D.; Elvington, M. & Click, D.
Partner: UNT Libraries Government Documents Department