Sample records for thermal cracking delayed

  1. Stress Corrosion Cracking and Delayed Increase in Penetration Resistance after Dynamic Compaction of Sand

    E-Print Network [OSTI]

    Michalowski, Radoslaw L.

    Stress Corrosion Cracking and Delayed Increase in Penetration Resistance after Dynamic Compaction on the process of stress corrosion cracking of the micro-morphological features on the surface of the sand grains

  2. Thermal cracking in disc brakes Thomas J. Mackin *,1

    E-Print Network [OSTI]

    Salvaggio, Carl

    Thermal cracking in disc brakes Thomas J. Mackin *,1 , Steven C. Noe, K.J. Ball, B.C. Bedell, D, or hub, which is connected to the wheel and axle, and an inboard and outboard braking surface

  3. Prediction of thermal reflection cracking in west Texas

    E-Print Network [OSTI]

    Chang, Hang-Sun

    1975-01-01T23:59:59.000Z

    for the stress intensity factor, Ck, following Barenblatt (53) is used. z 'e(')4' C = ? / k n o (3-11) where C is the distance away from crack tip and o (g) is the surface e stress inside the crack tip element, i. e. ? o is the thermal stress at the depth... of the studies being conducted on pavement temp- erature cracking have been mainly concerned with the fracture suscepti- bilityy of asphalt concrete under extremely low temperature (3, 4). Find- ings of these studies could not provide satisfactory...

  4. Thermal resistance of bridged cracks in fiber-reinforced ceramic John Dryden

    E-Print Network [OSTI]

    Zok, Frank

    -reinforced ceramic composites obtain high toughness is through the de- velopment of multiple matrix cracksThermal resistance of bridged cracks in fiber-reinforced ceramic composites John Dryden Department November 2000; accepted for publication 16 January 2001 The thermal resistance of a bridged matrix crack

  5. Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite

    E-Print Network [OSTI]

    Zok, Frank

    Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite of Engineering Science, University of Western Ontario, London, Ontario N6A 5B9, Canada Effects of matrix cracks conductances coupled with a unit cell model for a fiber composite containing a periodic array of matrix cracks

  6. Enlargement of concrete blocks of arch dams with allowance of the formation of radial thermal cracks

    SciTech Connect (OSTI)

    Verbetskii, G.P.; Chogovadze, G.I.; Daneliya, A.I.

    1988-04-01T23:59:59.000Z

    Considerable acceleration of the construction of arch dams with the use of highly productive continuous concreting mechanisms is possible with enlargement of the blocks and allowance of the formation of thermal radial cracks in them. A theoretical analysis and the results of on-site observations show that under the effect of the hydrostatic head of water, radial joints and cracks in compressed zones of an arch dam close and the dam in these zones works as a solid dam. Thermal cracking in concrete blocks of arch dams enlarged in plan should be controlled by making radial notches to concentrate tensile stresses providing the formation of radial cracks at prescribed places and through the usual methods of thermal regulation. The block size along the face of an arch dam is then no longer limited by the condition of crack resistance but is determined by the rate of concreting. The technical and economic effects from concreting arch dams are cited.

  7. A probabilistic model to predict the formation and propagation of crack networks in thermal

    E-Print Network [OSTI]

    . In the case of cooling systems in nuclear power plants, observations revealed the presence of thermal crazing loading even if thermal fatigue is multiaxial. However, the first simulations on a uniaxial mechanicalA probabilistic model to predict the formation and propagation of crack networks in thermal fatigue

  8. The effect of fluence and irradiation temperature on delayed hydride cracking in Zr-2.5Nb

    SciTech Connect (OSTI)

    Sagat, S.; Coleman, C.E.; Griffiths, M. [AECL Research, Chalk River, Ontario (Canada); Wilkins, B.J.S. [AECL Research, Pinawa, Manitoba (Canada)

    1994-12-31T23:59:59.000Z

    Zirconium alloys are susceptible to a stable cracking process called delayed hydride cracking (DHC). DHC has two stages: (a) crack initiation that requires a minimum crack driving force (the threshold stress intensity factor, K{sub IH}) and (b) stable crack growth that is weakly dependent on K{sub l}. The value of K{sub lH} is an important element in determining the tolerance of components to sharp flaws. The rate of cracking is used in estimating the action time for detecting propagating cracks before they become unstable. Hence, it is important for reactor operators to know how these properties change during service in reactors where the components are exposed to neutron irradiation at elevated temperatures. DHC properties were measured on a number of components, made from the two-phase alloy Zr-2.5 Nb, irradiated at temperatures in the range of 250 to 290 C in fast neutron fluxes (E {>=} 1 MeV) between 1.6 {times} 10{sup 17} and 1.8 {times} 10{sup 18} n/m{sup 2} {center_dot} s to fluences between 0.01 {times} 10{sup 25} and 9.8 {times} 10{sup 25} n/m{sup 2}. The neutron irradiation reduced K{sub IH} by about 20% and increased the velocity of cracking by a factor of about five. The increase in crack velocity was greatest with the lowest irradiation temperature. These changes in the rack velocity by neutron irradiation are explained in terms of the combined effects of irradiation hardening associated with increased -type dislocation density, and {beta}-phase decomposition. While the former process increases crack velocity, the latter process decrease it. The combined contribution is controlled by the irradiation temperature. X-ray diffraction analyses showed that the degree of {beta}-phase decomposition was highest with an irradiation temperature of 290 C while -type dislocation densities were highest with an irradiation temperature of 250 C.

  9. Effect of cracks on the thermal resistance of aligned fiber composites Department of Mechanical and Materials Engineering, University of Western Ontario, London,

    E-Print Network [OSTI]

    Zok, Frank

    Effect of cracks on the thermal resistance of aligned fiber composites J. Dryden Department are bridged by the fibers, and this crack- ing causes an increase in the longitudinal thermal resistance of the matrix and the fiber, respectively. The thermal resistance of a pristine unit cell is R0 L b2 kz . 4

  10. Roles of grain boundaries in cleavage cracking and thermal crack arrest experiments in iron-silicon alloy

    E-Print Network [OSTI]

    Qiao, Yu, 1972-

    2002-01-01T23:59:59.000Z

    High-angle grain boundaries in steel offer an important resistance to the propagation of cleavage cracks that affects the fracture toughness and can modulate the ductile-to-brittle transition temperature of fracture downward. ...

  11. Gamma prime embrittlement and thermal fatigue cracking of a hydrogen reformer burner end

    SciTech Connect (OSTI)

    Dias, O.C.; Mack, N.C. [Amoco Oil Co., Texas City, TX (United States)

    1994-12-31T23:59:59.000Z

    An investigation into the premature failure of an Alloy 800HT (UNS N08811) oxygen-gas mixer water jacketed end is discussed. Detailed metallurgical analyses showed that gamma prime [Ni{sub 3} (Al, Ti)] embrittlement and thermal fatigue cracking led to eventual leakage. The reduced lif e of the Alloy 800HT (UNS N08811) replacement (problems after only a year) was traced to its higher Al + Ti content (1.1%) compared to Alloy 800H (0.6% Al + Ti) which lasted over two years. While higher aluminum and titanium levels improve high temperature creep and stress rupture properties, both are sigma formers and, at levels > 0.6%, tend to form gamma prime with nickel. The choice of alternative metallurgies requires careful considerations of physical, mechanical and thermal properties as well as an understanding of complex stresses and stress distributions.

  12. Yields of delayed-neutron groups in thermal-neutron fission of sup 229 Th

    SciTech Connect (OSTI)

    Gudkov, A.N.; Koldobskii, A.B.; Krivasheev, S.V.; Lebedev, N.A.; Pchelin, V.A. (Moscow Engineering-Physics Institute (SU))

    1989-06-01T23:59:59.000Z

    Absolute yields of five delayed-neutron groups in thermal-neutron fission of {sup 229}Th have been determined for the first time. A significant discrepancy is noted between the experimental yields of delayed neutrons of the fourth group and the corresponding theoretical values. From the results of the experimental studies, corrections have been determined for even--odd effects in the charge distributions of the yields of fragment nuclides.

  13. Analysis of the effective delayed neutron fraction in the coupled fast-thermal system HERBE

    SciTech Connect (OSTI)

    Milosevic, M.; Pesic, M.; Avdic, S.; Nikolic, D. [Institute of Nuclear Sciences, Beograd (Yugoslavia)

    1994-12-31T23:59:59.000Z

    The results of measurements {beta}{sub eff} and {beta}{sub eff}/{Lambda} and calculation results based on various sets of evaluated six-group delayed neutron parameters for the coupled fast-thermal system HERBE are shown in this paper.

  14. Sulfur distribution in the oil fractions obtained by thermal cracking of Jordanian El-Lajjun oil Shale

    E-Print Network [OSTI]

    Shawabkeh, Reyad A.

    by the thermal cracking process of the El-Lujjan oil shale showed that the yield of oil was around 12 wt of the boiling point for different distillate fractions. Sulfur in Jordanian oil shale was found to be mainly the dominant phases in these fractions. q 2005 Published by Elsevier Ltd. 1. Introduction Oil shale

  15. Measurement of delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons

    SciTech Connect (OSTI)

    Gundorin, N. A.; Zhdanova, K. V.; Zhuchko, V. E.; Pikelner, L. B., E-mail: plb@nf.jinr.ru; Rebrova, N. V.; Salamatin, I. M.; Smirnov, V. I.; Furman, V. I. [Joint Institute for Nuclear Research (Russian Federation)

    2007-06-15T23:59:59.000Z

    The delayed-neutron yield from thermal-neutron-induced fission of the {sup 237}Np nucleus was measured using a sample periodically exposed to a pulsed neutron beam with subsequent detection of neutrons during the time intervals between pulses. The experiment was realized on an Isomer-M setup mounted in the IBR-2 pulsed reactor channel equipped with a mirror neutron guide. The setup and the experimental procedure are described, the background sources are thoroughly analyzed, and the experimental data are presented. The total delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons is {nu}{sub d} = 0.0110 {+-} 0.0009. This study was performed at the Frank Laboratory of Neutron Physics (JINR, Dubna)

  16. WATTS TOWERS: THE EFFECTS OF THERMAL CYCLES ON THE FORMATION AND BEHAVIOR OF CRACKS

    E-Print Network [OSTI]

    Spencer, Matthew T

    2013-02-06T23:59:59.000Z

    The development of cracks in Portland Cement Concrete (PCC) and Grout has become a problem of rising concern in a country with an aging infrastructure. A detailed understanding of the causes as well as the behavior of these cracks is vital...

  17. Effects of thermal aging on Stress Corrosion Cracking and mechanical properties of stainless steel weld metals

    E-Print Network [OSTI]

    Hixon, Jeff

    2006-01-01T23:59:59.000Z

    Stress Corrosion Cracking (SCC) in and around primary loop piping welds in Boiling Water Reactors has been observed worldwide as plants continue to operate at temperatures and pressures near 2880C (5500F) and 6.9 MPa (1000 ...

  18. Yield of delayed neutrons in the thermal-neutron-induced reaction {sup 245}Cm(n, f)

    SciTech Connect (OSTI)

    Andrianov, V. R. [Joint Institute for Nuclear Research (Russian Federation); Vyachin, V. N. [All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Gundorin, N. A. [Joint Institute for Nuclear Research (Russian Federation); Druzhinin, A. A. [All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Zhdanova, K. V.; Lihachev, A. N.; Pikelner, L. B.; Rebrova, N. V.; Salamatin, I. M.; Furman, V. I. [Joint Institute for Nuclear Research (Russian Federation)

    2008-10-15T23:59:59.000Z

    The yield of delayed neutrons, v{sub d}, from thermal-neutron-induced fission of {sup 245}Cm is measured. Experiments aimed at studying the properties of delayed neutrons from the fission of some reactor isotopes and initiated in 1997 were continued at the upgraded Isomer-M facility by a method according to which a periodic irradiation of a sample with a pulsed neutron beam from the IBR-2 reactor was accompanied by recording emitted neutrons in the intervals between the pulses. The accuracy of the resulting total delayed-neutron yield v{sub d} = (0.64 {+-} 0.02)% is two times higher than that in previous measurements. This work was performed at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (JINR, Dubna).

  19. On the analysis method of effective delayed neutron fraction at thermal neutron systems

    SciTech Connect (OSTI)

    Nakajima, K.; Unesaki, H. [Research Reactor Inst., Kyoto Univ., Asashiro-Nishi 2, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2006-07-01T23:59:59.000Z

    The effective delayed neutron fraction (beta-effective) was numerically analyzed with different analysis methods, and their effects on the results were investigated. The cores investigated in this study were light-water moderated low enriched UO{sub 2} lattices, of which the beta-effective had been reported. The effects of transport/diffusion calculation, energy group collapsing, and change of nuclear data library were studied. The study showed that the diffusion calculation with coarse group cross section gave smaller beta-effective than the transport one with fine group cross section, although the difference was not so large, about 2%. On the other hand, the change of nuclear data library from JENDL-3.3 to ENDF/B-VI.8 gave a significant difference, over than 4%. In comparisons with the experiments, it was indicated that the delayed neutron data in JENDL-3.3 are more reliable than those in ENDF/B-VI.8. (authors)

  20. Combustion in cracks of PBX 9501

    SciTech Connect (OSTI)

    Berghout, H. L. (Henry L.); Son, S. F. (Steven F.); Bolme, C. A. (Cynthia A.); Hill, L. G. (Larry G.); Asay, B. W. (Blaine W.); Dickson, P. M. (Peter M.); Henson, B. F. (Bryan F.); Smilowitz, L. B. (Laura B.)

    2002-01-01T23:59:59.000Z

    Recent experiments involving the combustion of PBX 9501 explosive under confined conditions reveal the importance of crack and flaws in reaction violence. Experiments on room temperature confined disks of pristine and thermally damaged PBX 9501 reveal that crack ignition depends on hot gases entering existing or pressure induced cracks rather than on energy release at the crack tip. PBX 9501 slot combustion experiments show that the reaction propagation rate in the slot does not depend on the external pressure. We have observed 1500 d s in long slots of highly-confined PBX 9501. We present experiments that examine the combustion of mechanically and thermally damaged samples of PBX 9501.

  1. Creep failure of cracking heater at a petrochemical plant

    SciTech Connect (OSTI)

    El-Batahgy, A. [Welding Research Department, Central, Metallurgical R and D Institute, Cairo (Egypt)]. E-mail: elbatahgy@yahoo.com; Zaghloul, B. [Central Metallurgical R and D Institute, P.O. Box: 87 Helwan, Cairo (Egypt)

    2005-03-15T23:59:59.000Z

    After two and half years of operation, a bend tube in a cracking heater at an ethylene plant failed due to creep cracking. Creep damage occurred as a result of metallurgical instability including coarsening of carbides that caused softening and initiation of voids or wedge-type intergranular cracks. This was accelerated due to increasing inner surface temperature during decoking process. Thermal fatigue contributed to the failure as a result of temperature variations due to several shutdown-startup operations. To minimize such failure in futures, periodic inspection to monitor crack formation was scheduled. Nondestructive tests including dye penetrant test for surface cracking and radiographic test for internal crack were implemented.

  2. Vehicle barrier with access delay

    DOE Patents [OSTI]

    Swahlan, David J; Wilke, Jason

    2013-09-03T23:59:59.000Z

    An access delay vehicle barrier for stopping unauthorized entry into secure areas by a vehicle ramming attack includes access delay features for preventing and/or delaying an adversary from defeating or compromising the barrier. A horizontally deployed barrier member can include an exterior steel casing, an interior steel reinforcing member and access delay members disposed within the casing and between the casing and the interior reinforcing member. Access delay members can include wooden structural lumber, concrete and/or polymeric members that in combination with the exterior casing and interior reinforcing member act cooperatively to impair an adversarial attach by thermal, mechanical and/or explosive tools.

  3. The energy spectrum of delayed neutrons from thermal neutron induced fission of sup 2 sup 3 sup 5 U and its analytical approximation

    E-Print Network [OSTI]

    Doroshenko, A Y; Tarasko, M Z

    2001-01-01T23:59:59.000Z

    The energy spectrum of the delayed neutrons is the poorest known of all input data required in the calculation of the effective delayed neutron fractions. In addition to delayed neutron spectra based on the aggregate spectrum measurements there are two different approaches for deriving the delayed neutron energy spectra. Both of them are based on the data related to the delayed neutron spectra from individual precursors of delayed neutrons. In present work these two different data sets were compared with the help of an approximation by gamma-function. The choice of this approximation function instead of the Maxwellian or evaporation type of distribution is substantiated.

  4. Linking Grain Boundary Structure and Composition to Intergranular Stress Corrosion Cracking of Austenitic Stainless Steels

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.

    2004-08-10T23:59:59.000Z

    Grain boundary structure and composition is assessed in austenitic stainless steels along with its influence on intergranular stress corrosion cracking (IGSCC) in high-temperature water. Brief examples are presented illustrating effects of grain boundary character and segregation on behavior in specific light-water-reactor environments. Although grain boundary engineering can produce an increased fraction of special boundaries in austenitic stainless alloys, practical benefits depend on the boundary orientation distribution. It is critical to recognize that only coherent sigma 3s appear to be resistant to SCC and the behavior of other low sigma boundaries is uncertain. Grain boundary composition can have a dominant effect on IGSCC under certain conditions, but altered interfacial chemistry is not required for cracking. In high-potential oxidizing environments, IGSCC susceptibility is a direct function of the boundary Cr concentration. Non-equilibrium thermal segregation of Cr and Mo is often present in millannealed stainless steels and may influence cracking susceptibility. This initial grain boundary composition alters subsequent radiation-induced segregation and delays irradiation-assisted SCC susceptibility to higher doses. Other alloying elements and impurities in 300-series stainless steels have been seen to enrich grain boundaries, but few have any significant impact on IGSCC susceptibility. One exception is Si that strongly segregates during irradiation. recent results suggest that Si may accelerate crack propagation in both low- and high-potential water environments. Critical research is still needed to isolate individual grain boundary characteristics and quantitatively link to IGSCC.

  5. Crack coalescence in granite

    E-Print Network [OSTI]

    Miller, James Thomas, Ph. D. Massachusetts Institute of Technology

    2008-01-01T23:59:59.000Z

    This thesis experimentally investigates crack coalescence in prismatic Barre Granite specimens with two pre-cut, open flaws under uniaxial compression. Using a high-speed video system, crack initiation, propagation, and ...

  6. Application of the cracked pipe element to creep crack growth prediction

    SciTech Connect (OSTI)

    Brochard, J.; Charras, T.

    1997-04-01T23:59:59.000Z

    The modification of a computer code for leak before break analysis is very briefly described. The CASTEM2000 code was developed for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading. The modification extends the capabilities of the cracked pipe element to the determination of fracture parameters under creep conditions (C*, {phi}c and {Delta}c). The model has the advantage of evaluating significant secondary effects, such as those from thermal loading.

  7. Application of the cracked pipe element to creep crack growth prediction

    SciTech Connect (OSTI)

    Brochard, J.; Charras, T. [C.E.A.-C.E.-Saclay DRN/DMT, Gif Sur Yvette (France); Ghoudi, M. [C.E.A.-C.E.-Saclay, Gif Sur Yvette (France)

    1997-04-01T23:59:59.000Z

    Modifications to a computer code for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading are very briefly described. The modifications extend the capabilities of the CASTEM2000 code to the determination of fracture parameters under creep conditions. The main advantage of the approach is that thermal loads can be evaluated as secondary stresses. The code is applicable to piping systems for which crack propagation predictions differ significantly depending on whether thermal stresses are considered as primary or secondary stresses.

  8. Crack isobutane for isobutylene

    SciTech Connect (OSTI)

    Soudek, M. (Coastal States Management Corp., Houston, TX (US)); Lacatena, J.J. (Foster Wheeler USA Corp., Clinton, NJ (US))

    1990-05-01T23:59:59.000Z

    This paper describes the coastal isobutane cracking process which cracks isobutane under controlled conditions in the presence of steam utilizing efficient tubular furnaces and produces high propylene and isobutylene yields. The authors list the options to which this process lends itself.

  9. Determination of crack morphology parameters from service failures for leak-rate analyses

    SciTech Connect (OSTI)

    Wilkowski, G.; Ghadiali, N.; Paul, D. [Battelle Memorial Institute, Columbus, OH (United States)] [and others

    1997-04-01T23:59:59.000Z

    In leak-rate analyses described in the literature, the crack morphology parameters are typically not well agreed upon by different investigators. This paper presents results on a review of crack morphology parameters determined from examination of service induced cracks. Service induced cracks were found to have a much more tortuous flow path than laboratory induced cracks due to crack branching associated with the service induced cracks. Several new parameters such as local and global surface roughnesses, as well as local and global number of turns were identified. The effect of each of these parameters are dependent on the crack-opening displacement. Additionally, the crack path is typically assumed to be straight through the pipe thickness, but the service data show that the flow path can be longer due to the crack following a fusion line, and/or the number of turns, where the number of turns in the past were included as a pressure drop term due to the turns, but not the longer flow path length. These parameters were statistically evaluated for fatigue cracks in air, corrosion-fatigue, IGSCC, and thermal fatigue cracks. A refined version of the SQUIRT leak-rate code was developed to account for these variables. Sample calculations are provided in this paper that show how the crack size can vary for a given leak rate and the statistical variation of the crack morphology parameters.

  10. Elevated temperature crack propagation

    SciTech Connect (OSTI)

    Orange, T.W.

    1994-02-01T23:59:59.000Z

    This paper is a summary of two NASA contracts on high temperature fatigue crack propagation in metals. The first evaluated the ability of fairly simple nonlinear fracture parameters to correlate crack propagation. Hastelloy-X specimens were tested under isothermal and thermomechanical cycling at temperatures up to 980 degrees C (1800 degrees F). The most successful correlating parameter was the crack tip opening displacement derived from the J-integral. The second evaluated the ability of several path-independent integrals to correlate crack propagation behavior. Inconel 718 specimens were tested under isothermal, thermomechanical, temperature gradient, and creep conditions at temperatures up to 650 degrees C (1200 degrees F). The integrals formulated by Blackburn and by Kishimoto correlated the data reasonably well under all test conditions.

  11. Evaluation of cracking in steam generator feedwater piping in pressurized water reactor plants

    SciTech Connect (OSTI)

    Goldberg, A.; Streit, R.D.

    1981-05-01T23:59:59.000Z

    Cracking in feedwater piping was detected near the inlet to steam generators in 15 pressurized water reactor plants. Sections with cracks from nine plants are examined with the objective of identifying the cracking mechanism and assessing various factors that might contribute to this cracking. Using transmission electron microscopy, fatigue striations are observed on replicas of cleaned crack surfaces. Calculations based on the observed striation spacings gave a cyclic stress value of 150 MPa (22 ksi) for one of the major cracks. The direction of crack propagation was invariably related to the piping surface and not to the piping axis. These two factors are consistent with the proposed concept of thermally induced, cyclic, tensile surface stresses and it is concluded that the overriding factor in the cracking problem was the presence of such undocumented cyclic loads.

  12. Uncertainty evaluation of delayed neutron decay parameters

    E-Print Network [OSTI]

    Wang, Jinkai

    2009-05-15T23:59:59.000Z

    parameters fit their individual measurement data well in spite of these differences. This dissertation focuses on evaluation of the errors and methods of delayed neutron relative yields and decay constants for thermal fission of U-235. Various numerical...

  13. PHYSICAL REVIEW E 84, 036104 (2011) Average crack-front velocity during subcritical fracture propagation in a heterogeneous medium

    E-Print Network [OSTI]

    Schmittbuhl, Jean

    PHYSICAL REVIEW E 84, 036104 (2011) Average crack-front velocity during subcritical fracture]. In consequence the slow kinetic crack propagation is usually referred to as subcritical crack growth or the subcritical regime. Statistical physics models suggest that this subcritical regime is governed by a thermally

  14. Crack propagation in Hastelloy X

    SciTech Connect (OSTI)

    Weerasooriya, T.; Strizak, J.P.

    1980-05-01T23:59:59.000Z

    The fatigue and creep crack growth rates of Hastelloy X were examined both in air and impure helium. Creep crack growth rate is higher in air and impure helium at 650/sup 0/C. Initial creep crack growth from the original sharp fatigue crack is by an intergranular mode of fracture. As the cracking accelerates at higher stress intensities, growth is by a mixed mode of both intergranular and transgranular fracture. Fatigue crack growth rate increases with increasing temperature and decreasing frequency for the range of stress intensities reported in the literature and is lower in impure helium than in air.

  15. Atomic origin of hysteresis during cyclic loading of Si due to bond rearrangements at the crack surfaces

    E-Print Network [OSTI]

    Carter, Emily A.

    that invokes mechanically induced subcritical cracking to explain the delayed onset of failure. © 2005 American associated with a larger initial flaw, which is assumed to be caused by subcritical crack growth, 5- time during high cycle fatigue if water is present, and 6 a fatigue lifetime that depends only

  16. Reflective Cracking Study: Summary Report

    E-Print Network [OSTI]

    Jones, David; Harvey, John T; Monismith, Carl L.

    2008-01-01T23:59:59.000Z

    Cracking Study: First-level Report on Laboratory ShearStudy: Second-Level Analysis Report. Davis and Berkeley, CA:Cracking Study: First-level Report on HVS Testing on Section

  17. Hydrocarbon cracking catalyst

    SciTech Connect (OSTI)

    Lochow, C.F.; Kovacs, D.B.

    1988-12-27T23:59:59.000Z

    This patent describes a catalyst composition for cracking hydrocarbons to maximize gasoline comprising: rare earth exchanged ''Y'' crystalline faujasite dispersed in a clay containing matrix material; and which has been subsequently further ion exchanged to contain 0.20 to 3.0 wt% yttrium, calculated as the oxide, whereby the yttrium is chemically combined in the catalyst composition.

  18. Thermally activated delayed fluorescence from {sup 3}n?* to {sup 1}n?* up-conversion and its application to organic light-emitting diodes

    SciTech Connect (OSTI)

    Li, Jie; Zhang, Qisheng; Nomura, Hiroko [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Miyazaki, Hiroshi [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Functional Materials Laboratory, Nippon Steel and Sumikin Chemical Co., Ltd, 46–80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804–8503 (Japan); Adachi, Chihaya, E-mail: adachi@cstf.kyushu-u.ac.jp [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

    2014-07-07T23:59:59.000Z

    Intense n?* fluorescence from a nitrogen-rich heterocyclic compound, 2,5,8-tris(4-fluoro-3-methylphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3MF), is demonstrated. The overlap-forbidden nature of the n?* transition and the higher energy of the {sup 3}??* state than the {sup 3}n?* one lead to a small energy difference between the lowest singlet (S{sub 1}) and triplet (T{sub 1}) excited states of HAP-3MF. Green-emitting HAP-3MF has a moderate photoluminescence quantum yield of 0.26 in both toluene and doped film. However, an organic light-emitting diode containing HAP-3MF achieved a high external quantum efficiency of 6.0%, indicating that HAP-3MF harvests singlet excitons through a thermally activated T{sub 1} ? S{sub 1} pathway in the electroluminescent process.

  19. Causes and solutions for cracking of coextruded and weld overlay floor tubes in black liquor recovery boilers

    SciTech Connect (OSTI)

    Keiser, J.R.; Taljat, B.; Wang, X.L. [and others

    1998-09-01T23:59:59.000Z

    Cracking of coextruded, black liquor recovery boiler floor tubes is both a safety and an economic issue to mill operators. In an effort to determine the cause of the cracking and to identify a solution, extensive studies, described in this and three accompanying papers, are being conducted. In this paper, results of studies to characterize both the cracking and the chemical and thermal environment are reported. Based on the results described in this series of papers, a possible mechanism is presented and means to lessen the likelihood of cracking or to totally avoid cracking of floor tubes are offered.

  20. Crack-resistant siloxane molding compounds. [Patent application

    DOE Patents [OSTI]

    McFarland, J.W.; Swearngin, C.B.

    1980-11-03T23:59:59.000Z

    The crack resistance of phenyl silicone molding resins containing siliceous fillers is improved by incorporating therein about 0.5 to 5.5% by weight of ..beta..-eucryptite, a lithium aluminum silicate having a negative thermal expansion coefficient. These molding resins are particularly suitable for encapsulating electronic devices such as diodes, coils, resistors, and the like.

  1. Shrinkage - cracking characteristics of structural lightweight concrete

    E-Print Network [OSTI]

    McKeen, Robert Gordon

    1969-01-01T23:59:59.000Z

    'P'D. ) FIGURE 4-14 Cracking as Indi. cat d by Nater Loss PACE IO 5-1 Thermal Expansion Correction by Emtrspolation /7 LZST OP TAELES TAELE Environments 35 Test. ing Program. Statistical Data Direct Tensile Specim n Data 59 4-3 Comparison of Selected.... Cement contents of 5, 0, 6. 0 ind 6. 5 i a~n. , /ci-hie yorri were used. Unrestraineii volume changes wcr liaaoi - . . i o! standard type specimens (3 x 3 x i 1. 25 . in, ) . Craciring i'!ali!ai. cd ns thi! number of ccac!. s occurring on a s, ~ i...

  2. Status Report on Studies of Recovery Boiler Composite Floor Tube Cracking

    SciTech Connect (OSTI)

    Eng, P.; Frederick, L.A.; Hoffmann, C.M.; Keiser, J.R.; Mahmood, J.; Maziasz, P.J.; Prescott, R.; Sarma, G.B.; Singbeil, D.L.; Singh, P.M.; Swindeman, R.W.; Wang, X.-L.

    1999-09-12T23:59:59.000Z

    Cracking of the stainless steel layer of co-extruded 304L stainless steel/SA210 Gd A 1 carbon steel black liquor recovery boiler floor tubes has been identified as one of the most serious material problems in the pulp and paper industry. A DOE-funded study was initiated in 1995 with the goal of determining the cause of and possible solutions to this cracking problem. These studies have characterized tube cracking as well as the chemical and thermal environment and stress state of floor tubes. Investigations of possible cracking mechanisms indicate that stress corrosion cracking rather than thermal fatigue is a more likely cause of crack initiation. The cracking mechanism appears to require the presence of hydrated sodium sulfide and is most likely active during shut-downs and/or start-ups. Based on these results and operating experience, certain alloys appear to be more resistant than others to cracking in the floor environment, and certain operating practices appear to significantly lessen the likelihood of cracking. This report is the latest in a series of progress reports presented on this project.

  3. Identifying and Understanding Environment-Induced Crack propagation Behavior in Ni-based Superalloy INCONEL 617

    SciTech Connect (OSTI)

    Longzhou Ma

    2012-11-30T23:59:59.000Z

    The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or SAGBOE damage process under hold-time fatigue and sustained loading conditions

  4. Stress corrosion crack growth in porous sandstones. 

    E-Print Network [OSTI]

    Ojala, Ira O

    Stress corrosion crack growth occurs when the chemical weakening of strained crack tip bonds facilitates crack propagation. I have examined the effect of chemical processes on the growth of a creack population by carrying out triaxial compression...

  5. Discrete Element Model for Simulations of Early-Life Thermal Fracturing Behaviors in Ceramic Nuclear Fuel Pellets

    SciTech Connect (OSTI)

    Hai Huang; Ben Spencer; Jason Hales

    2014-10-01T23:59:59.000Z

    A discrete element Model (DEM) representation of coupled solid mechanics/fracturing and heat conduction processes has been developed and applied to explicitly simulate the random initiations and subsequent propagations of interacting thermal cracks in a ceramic nuclear fuel pellet during initial rise to power and during power cycles. The DEM model clearly predicts realistic early-life crack patterns including both radial cracks and circumferential cracks. Simulation results clearly demonstrate the formation of radial cracks during the initial power rise, and formation of circumferential cracks as the power is ramped down. In these simulations, additional early-life power cycles do not lead to the formation of new thermal cracks. They do, however clearly indicate changes in the apertures of thermal cracks during later power cycles due to thermal expansion and shrinkage. The number of radial cracks increases with increasing power, which is consistent with the experimental observations.

  6. Thermal Shock-resistant Cement

    SciTech Connect (OSTI)

    Sugama T.; Pyatina, T.; Gill, S.

    2012-02-01T23:59:59.000Z

    We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200 and #61616;C-autoclaved cement at 500 and #61616;C for 24 hours, and then the heated cement was rapidly immersed in water at 25 and #61616;C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5-cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite and #61614; and #61543;-Al2O3, katoite and #61614; calcite, and hydroxysodalite and #61614; carbonated sodalite. Among those, the hydroxysodalite and #61614; carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved cement, causing its volume to expand.

  7. Peridynamic model for fatigue cracking.

    SciTech Connect (OSTI)

    Silling, Stewart A.; Abe Askari (Boeing)

    2014-10-01T23:59:59.000Z

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the %22remaining life%22 of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  8. Cracking behavior of cored structures

    SciTech Connect (OSTI)

    Wahid, A.; Olson, D.L.; Matlock, D.K. (Colorado School of Mines, Golden, CO (United States). Center for Welding and Joining Research); Kelly, T.J. (General Electric Aircraft Engines, Evendale, OH (United States))

    1991-01-01T23:59:59.000Z

    The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a composition gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Data on stress corrosion cracking and fatigue crack growth in selected FCC alloys are used to illustrate the significance of microsegregation on mechanical properties.

  9. Environmental stress cracking of plastics under dynamic conditions

    E-Print Network [OSTI]

    Suresh, Mitta

    1992-01-01T23:59:59.000Z

    The objective of this study was to find out if dynamic conditions have any effect on the phenomenon of environmental stress cracking (ESC). Dynamic conditions in this study include thermal shock, mechanical shock, and vibrations. Injection blow molded... resistance of blow molded polyethylene containers. The experimental data indicated that each of the dynamic conditions accelerated the ESC. Therefore, the results obtained from the static tests cannot be used to predict the service life of the containers...

  10. Degradation of Structural Alloys Under Thermal Insulation

    E-Print Network [OSTI]

    McIntyre, D. R.

    1984-01-01T23:59:59.000Z

    Wet thermal insulation may actively degrade steel and stainless steel structures by general corrosion or stress-corrosion cracking. Two different mechanisms of water ingress into insulation are discussed; flooding from external sources...

  11. Evaluation of cracking in feedwater piping adjacent to the steam generators in Nine Pressurized Water Reactor Plants

    SciTech Connect (OSTI)

    Goldberg, A.; Streit, R.D.; Scott, R.G.

    1980-06-25T23:59:59.000Z

    Cracking in ASTM A106-B and A106-C feedwater piping was detected near the inlet to the steam generators in a number of pressurized water reactor plants. We received sections with cracks from nine of the plants with the objective of identifying the cracking mechanism and assessing various factors that might contribute to this cracking. Variations were observed in piping surface irregularities, corrosion-product, pit, and crack morphology, surface elmental and crystal structure analyses, and steel microstructures and mechanical properties. However, with but two exceptions, namely, arrest bands and major surface irregularities, we were unable to relate the extent of cracking to any of these factors. Tensile and fracture toughness (J/sub Ic/ and tearing modulus) properties were measured over a range of temperatures and strain rates. No unusual properties or microstructures were observed that could be related to the cracking problem. All crack surfaces contained thick oxide deposits and showed evidence of cyclic events in the form of arrest bands. Transmission electron microscopy revealed fatigue striations on replicas of cleaned crack surfaces from one plant and possibly from three others. Calculations based on the observed striation spacings gave a value of ..delta..sigma = 150 MPa (22 ksi) for one of the major cracks. The direction of crack propagation was invariably related to the piping surface and not to the piping axis. These two factors are consistent with the proposed concept of thermally induced, cyclic, tensile surface stresses. Although surface irregularities and corrosion pits were sources for crack initiation and corrosion may have contributed to crack propagation, it is proposed that the overriding factor in the cracking problem is the presence of unforeseen cyclic loads.

  12. Crack propagation driven by crystal growth

    SciTech Connect (OSTI)

    A. Royne; Paul Meaking; A. Malthe-Sorenssen; B. Jamtveit; D. K. Dysthe

    2011-10-01T23:59:59.000Z

    Crystals that grow in confinement may exert a force on their surroundings and thereby drive crack propagation in rocks and other materials. We describe a model of crystal growth in an idealized crack geometry in which the crystal growth and crack propagation are coupled through the stress in the surrounding bulk solid. Subcritical crack propagation takes place during a transient period, which may be very long, during which the crack velocity is limited by the kinetics of crack propagation. When the crack is sufficiently large, the crack velocity becomes limited by the kinetics of crystal growth. The duration of the subcritical regime is determined by two non-dimensional parameters, which relate the kinetics of crack propagation and crystal growth to the supersaturation of the fluid and the elastic properties of the surrounding material.

  13. Nonlinear structural crack growth monitoring

    DOE Patents [OSTI]

    Welch, Donald E. (Oak Ridge, TN); Hively, Lee M. (Philadelphia, TN); Holdaway, Ray F. (Clinton, TN)

    2002-01-01T23:59:59.000Z

    A method and apparatus are provided for the detection, through nonlinear manipulation of data, of an indicator of imminent failure due to crack growth in structural elements. The method is a process of determining energy consumption due to crack growth and correlating the energy consumption with physical phenomena indicative of a failure event. The apparatus includes sensors for sensing physical data factors, processors or the like for computing a relationship between the physical data factors and phenomena indicative of the failure event, and apparatus for providing notification of the characteristics and extent of such phenomena.

  14. Delay in Atomic Photoionization

    SciTech Connect (OSTI)

    Kheifets, A. S. [Research School of Physical Sciences, Australian National University, Canberra ACT 0200 (Australia); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030 (United States); Ivanov, I. A. [Research School of Physical Sciences, Australian National University, Canberra ACT 0200 (Australia)

    2010-12-03T23:59:59.000Z

    We analyze the time delay between emission of photoelectrons from the outer valence ns and np subshells in noble gas atoms following absorption of an attosecond extreme ultraviolet pulse. Various processes such as elastic scattering of the photoelectron on the parent ion and many-electron correlation affect the apparent 'time zero' when the photoelectron leaves the atom. This qualitatively explains the time delay between photoemission from the 2s and 2p subshells of Ne as determined experimentally by attosecond streaking [Science 328, 1658 (2010)]. However, with our extensive numerical modeling, we were only able to account for less than half of the measured time delay of 21{+-}5 as. We argue that the extreme ultraviolet pulse alone cannot produce such a large time delay and it is the streaking IR field that is most likely responsible for this effect.

  15. Cracking Resistance of Asphalt Rubber Mix Versus

    E-Print Network [OSTI]

    Mobasher, Barzin

    . crack length curve for KR #12;Load vs. CMOD 0.0 0.5 1.0 1.5 2.0 Crack mouth opening, mm 0 500 1000 1500 non-linear fracture mechanics ·Compliance approach ·R-Curve approach #12;Conventional Fatigue Testing factor R-Curve approach Resistance to initiation & growth of cracks Evaluates fracture toughness

  16. Original article Stem cracks in Norway spruce

    E-Print Network [OSTI]

    Boyer, Edmond

    Original article Stem cracks in Norway spruce in southern Scandinavia: causes and consequences Garpenberg, Sweden (Received 1st September 1992; accepted 17 June 1993) Summary — Stem cracks in Norway;INTRODUCTION Background During this century, the widespread crack- ing of Norway spruce (Picea abies L Karst

  17. Downhole delay assembly for blasting with series delay

    DOE Patents [OSTI]

    Ricketts, Thomas E. (Grand Junction, CO)

    1982-01-01T23:59:59.000Z

    A downhole delay assembly is provided which can be placed into a blasthole for initiation of explosive in the blasthole. The downhole delay assembly includes at least two detonating time delay devices in series in order to effect a time delay of longer than about 200 milliseconds in a round of explosions. The downhole delay assembly provides a protective housing to prevent detonation of explosive in the blasthole in response to the detonation of the first detonating time delay device. There is further provided a connection between the first and second time delay devices. The connection is responsive to the detonation of the first detonating time delay device and initiates the second detonating time delay device. A plurality of such downhole delay assemblies are placed downhole in unfragmented formation and are initiated simultaneously for providing a round of explosive expansions. The explosive expansions can be used to form an in situ oil shale retort containing a fragmented permeable mass of formation particles.

  18. Environmentally assisted cracking of LWR materials

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Kassner, T.F.; Shack, W.J.

    1995-12-01T23:59:59.000Z

    Research on environmentally assisted cracking (EAC) of light water reactor materials has focused on (a) fatigue initiation in pressure vessel and piping steels, (b) crack growth in cast duplex and austenitic stainless steels (SSs), (c) irradiation-assisted stress corrosion cracking (IASCC) of austenitic SSs, and (d) EAC in high- nickel alloys. The effect of strain rate during different portions of the loading cycle on fatigue life of carbon and low-alloy steels in 289{degree}C water was determined. Crack growth studies on wrought and cast SSs have been completed. The effect of dissolved-oxygen concentration in high-purity water on IASCC of irradiated Type 304 SS was investigated and trace elements in the steel that increase susceptibility to intergranular cracking were identified. Preliminary results were obtained on crack growth rates of high-nickel alloys in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320{degree}C. The program on Environmentally Assisted Cracking of Light Water Reactor Materials is currently focused on four tasks: fatigue initiation in pressure vessel and piping steels, fatigue and environmentally assisted crack growth in cast duplex and austenitic SS, irradiation-assisted stress corrosion cracking of austenitic SSs, and environmentally assisted crack growth in high-nickel alloys. Measurements of corrosion-fatigue crack growth rates (CGRs) of wrought and cast stainless steels has been essentially completed. Recent progress in these areas is outlined in the following sections.

  19. Cascading of fluid cracking catalysts

    SciTech Connect (OSTI)

    Kovach, S.M.; Miller, C.B.

    1986-05-27T23:59:59.000Z

    A process is described for conversion of hydrocarbon feedstocks by cascading a cracking catalyst containing zeolite in an acidic matrix from one hydrocarbon processing unit to another, wherein there are at least three different interconnected hydrocarbon processing units comprising a first unit having a regeneration zone and a riser zone, a second unit having having a regeneration zone and a riser zone, and a third unit having a riser zone and a regeneration zone, each unit having different processing conditions.

  20. Delayed coking of decant oil and coal in a laboratory-scale coking unit

    SciTech Connect (OSTI)

    Oemer Guel; Leslie R. Rudnick; Harold H. Schobert [Pennsylvania State University Park, PA (United States). Energy Institute, C205 Coal Utilization Laboratory

    2006-08-15T23:59:59.000Z

    In this paper, we describe the development of a laboratory-scale delayed coker and present results of an investigation on the recovered liquid from the coking of decant oil and decant oil/coal mixtures. Using quantitative gas chromatography/mass spectroscopy (GC/MS) and {sup 1}H and {sup 13}C NMR, a study was made of the chemical composition of the distillate liquids isolated from the overheads collected during the coking and co-coking process. {sup 1}H and {sup 13}C NMR analyses of combined liquids from coking and co-coking did not show any substantial differences. These NMR results of coking and co-coking liquids agree with those of GC/MS. In these studies, it was observed that co-coking with coal resulted in a decrease in the paraffins contents of the liquid. The percentage of cycloparaffins, indenes, naphthalenes, and tetralins did not change significantly. In contrast, alkyl benzenes and polycyclic aromatic hydrocarbons in the distillate were higher in the co-coking experiments which may have resulted from the distillation of thermally cracked coal macromolecules and the contribution of these molecules to the overall liquid composition. 40 refs., 3 figs., 13 tabs.

  1. Stiffness reduction and stress transfer in composite laminates with transverse matrix cracks

    E-Print Network [OSTI]

    Praveen, Grama Narasimhaprasad

    2012-06-07T23:59:59.000Z

    -staggered cracking. Laminates with staggered cracks showed a greater reduction in effective modulus at lower crack densities. The crack opening displacements at different crack densities were normalized in a way as to compare with the solution for an isolated crack...

  2. A new mineralogical approach to predict coefficient of thermal expansion of aggregate and concrete

    E-Print Network [OSTI]

    Neekhra, Siddharth

    2005-02-17T23:59:59.000Z

    the construction allows for accurate prediction of the potential thermal change on crack development and crack width and enhances the overall design process. Siliceous gravel use results in larger crack width than does the limestone and at low temperature... increment between the contacts to the flask volume, the amount of aggregate in the flask, and the thermal characteristics of the aggregate. For measurements made below the freezing point of water, a non-reactive liquid, such as toluene, which does...

  3. ABSTRACT. The stress-relief cracking (SRC) susceptibility of single-pass welds

    E-Print Network [OSTI]

    DuPont, John N.

    steel, HCM2S, has been evaluated and compared to 2.25Cr-1Mo steel using Gleeble thermal simulation and pressure vessels for chemical and fossil power plants. Many components in these power plants oper- ate techniques. HCM2S was found to be more susceptible to stress-relief cracking than 2.25Cr-1Mo steel. Simulated

  4. Microstructural development and solidification cracking susceptibility of Cu deposits on steel: Part I

    E-Print Network [OSTI]

    DuPont, John N.

    Microstructural development and solidification cracking susceptibility of Cu deposits on steel industry is interested in depositing Cu onto steel using direct metal deposition techniques in order to improve thermal management of mold dies manufactured from steel alloys. However, Cu is a known promoter

  5. A NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED

    E-Print Network [OSTI]

    Paulino, Glaucio H.

    materials with high fracture toughness and elevated temperature resistance. Ideally, the ceramic side of the FGM provides thermal and corrosion resistance while the metallic side gives the necessary strengthA NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED MATERIALS

  6. Methodology for predicting asphalt concrete overlay life against reflection cracking

    E-Print Network [OSTI]

    Jayawickrama, Priyantha Warnasuriya

    1985-01-01T23:59:59.000Z

    of thermal expansion = change in temperature E K - (so gT) vc/h F3(c/h) +(I-u ) By defining, !40) (41) Jc/h F3(c/h) T Kt (42 ) 29 ~Summa r The proper variables to be used in a design equation and the form of the equation to be used is best... obtained are presented in this chapter. The stress intensity factor computations were carr1ed out for different crack-tip positions and for different levels of aggregate interlock act1on. These results were obtained for each of the three mechanisms...

  7. Study on grain boundary character and strain distribution of intergranular cracking in the CGHAZ of T23 steel

    SciTech Connect (OSTI)

    Jin, Y.J.; Lu, H., E-mail: shweld@sjtu.edu.cn; Yu, C.; Xu, J.J.

    2013-10-15T23:59:59.000Z

    Intergranular reheat cracking in the coarse-grained heat-affected zone of T23 steel was produced by strain to fracture tests on a Gleeble 3500 thermal–mechanical simulator. Then the grain boundary character, as well as the strain distribution after reheat crack propagation, was studied by electron backscatter diffraction technique. The results showed that incoherent ?3 boundaries were seldom found on the prior austenite grain boundaries. Therefore, only the type of random high-angle boundaries played a crucial role in the intergranular cracking. Microstructurally cavities and small cracks were preferentially initiated from high-angle grain boundaries. Low-angle grain boundaries and high-angle ones with misorientation angles less than 15° were more resistant to the cracking. More importantly, the fraction of high-angle grain boundaries increased with the plastic strain induced by both temperature gradient and stress in the coarse-grained heat-affected zone, which contributed to the crack initiation and propagation. Furthermore, the strain distributions in the vicinity of cavities and cracks revealed the accommodation processes of plastic deformation during stress relaxation. It also reflected the strength differences between grain interior and grain boundary at different heat-treated temperatures, which had a large influence on the cracking mechanism. - Highlights: • The coincidence site lattice boundaries play little role in the reheat cracking. • Cavity and crack occur at high-angle grain boundaries rather than low-angle ones. • The strain leads low-angle grain boundaries to transform to high-angle ones. • Strain distribution differs for cavity and crack zones at different temperatures.

  8. Congestion delays at hub airports

    E-Print Network [OSTI]

    St. George, Martin J.

    1986-01-01T23:59:59.000Z

    A deterministic model was developed to study the effects of inefficient scheduling on flight delays at hub airports. The model bases the delay calculation on published schedule data and on user-defined airport capacities. ...

  9. Crack stability analysis of low alloy steel primary coolant pipe

    SciTech Connect (OSTI)

    Tanaka, T.; Kameyama, M. [Kansai Electric Power Company, Osaka (Japan); Urabe, Y. [Mitsubishi Heavy Industries, Ltd., Takasago (Japan)] [and others

    1997-04-01T23:59:59.000Z

    At present, cast duplex stainless steel has been used for the primary coolant piping of PWRs in Japan and joints of dissimilar material have been applied for welding to reactor vessels and steam generators. For the primary coolant piping of the next APWR plants, application of low alloy steel that results in designing main loops with the same material is being studied. It means that there is no need to weld low alloy steel with stainless steel and that makes it possible to reduce the welding length. Attenuation of Ultra Sonic Wave Intensity is lower for low alloy steel than for stainless steel and they have advantageous inspection characteristics. In addition to that, the thermal expansion rate is smaller for low alloy steel than for stainless steel. In consideration of the above features of low alloy steel, the overall reliability of primary coolant piping is expected to be improved. Therefore, for the evaluation of crack stability of low alloy steel piping to be applied for primary loops, elastic-plastic future mechanics analysis was performed by means of a three-dimensioned FEM. The evaluation results for the low alloy steel pipings show that cracks will not grow into unstable fractures under maximum design load conditions, even when such a circumferential crack is assumed to be 6 times the size of the wall thickness.

  10. Biomaterials 24 (2003) 52095221 Crack blunting, crack bridging and resistance-curve fracture

    E-Print Network [OSTI]

    Ritchie, Robert

    Biomaterials 24 (2003) 5209­5221 Crack blunting, crack bridging and resistance-curve fracture focused on a description of the fracture toughness properties of dentin in terms of resistance-curve (R-curve) behavior, i.e., fracture resistance increasing with crack extension, particularly in light of the relevant

  11. Standard cosmology delayed

    SciTech Connect (OSTI)

    Choudhury, Debajyoti [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Ghoshal, Debashis [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Sen, Anjan Ananda, E-mail: debajyoti.choudhury@gmail.com, E-mail: dghoshal@mail.jnu.ac.in, E-mail: anjan.ctp@jmi.ac.in [Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi 110025 (India)

    2012-02-01T23:59:59.000Z

    The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

  12. Standard Cosmology Delayed

    E-Print Network [OSTI]

    Debajyoti Choudhury; Debashis Ghoshal; Anjan Ananda Sen

    2012-02-06T23:59:59.000Z

    The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

  13. Standard Cosmology Delayed

    E-Print Network [OSTI]

    Choudhury, Debajyoti; Sen, Anjan Ananda

    2011-01-01T23:59:59.000Z

    The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

  14. Programmable Differential Delay Circuit With Fine Delay Adjustment

    DOE Patents [OSTI]

    DeRyckere, John F. (Eau Claire, WI); Jenkins, Philip Nord (Eau Claire, WI); Cornett, Frank Nolan (Chippewa Falls, WI)

    2002-07-09T23:59:59.000Z

    Circuitry that provides additional delay to early arriving signals such that all data signals arrive at a receiving latch with same path delay. The delay of a forwarded clock reference is also controlled such that the capturing clock edge will be optimally positioned near quadrature (depending on latch setup/hold requirements). The circuitry continuously adapts to data and clock path delay changes and digital filtering of phase measurements reduce errors brought on by jittering data edges. The circuitry utilizes only the minimum amount of delay necessary to achieve objective thereby limiting any unintended jitter. Particularly, this programmable differential delay circuit with fine delay adjustment is designed to allow the skew between ASICS to be minimized. This includes skew between data bits, between data bits and clocks as well as minimizing the overall skew in a channel between ASICS.

  15. Modeling delay in genetic networks: From delay birth-death processes to delay stochastic differential equations

    E-Print Network [OSTI]

    Ott, William

    genetic circuits17­26 ; the infusion of delay dramatically enhances the stability of such circuits27

  16. Characterization of Fatigue Cracking and Healing of Asphalt Mixtures

    E-Print Network [OSTI]

    Luo, Xue

    2012-07-16T23:59:59.000Z

    Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing methods to characterize...

  17. Development of crack shape: LBB methodology for cracked pipes

    SciTech Connect (OSTI)

    Moulin, D.; Chapuliot, S.; Drubay, B. [Commissariat a l Energie Atomique, Gif sur Yvette (France)

    1997-04-01T23:59:59.000Z

    For structures like vessels or pipes containing a fluid, the Leak-Before-Break (LBB) assessment requires to demonstrate that it is possible, during the lifetime of the component, to detect a rate of leakage due to a possible defect, the growth of which would result in a leak before-break of the component. This LBB assessment could be an important contribution to the overall structural integrity argument for many components. The aim of this paper is to review some practices used for LBB assessment and to describe how some new R & D results have been used to provide a simplified approach of fracture mechanics analysis and especially the evaluation of crack shape and size during the lifetime of the component.

  18. Crack shape developments and leak rates for circumferential complex-cracked pipes

    SciTech Connect (OSTI)

    Brickstad, B.; Bergman, M. [SAQ Inspection Ltd., Stockholm (Sweden)

    1997-04-01T23:59:59.000Z

    A computerized procedure has been developed that predicts the growth of an initial circumferential surface crack through a pipe and further on to failure. The crack growth mechanism can either be fatigue or stress corrosion. Consideration is taken to complex crack shapes and for the through-wall cracks, crack opening areas and leak rates are also calculated. The procedure is based on a large number of three-dimensional finite element calculations of cracked pipes. The results from these calculations are stored in a database from which the PC-program, denoted LBBPIPE, reads all necessary information. In this paper, a sensitivity analysis is presented for cracked pipes subjected to both stress corrosion and vibration fatigue.

  19. SciTech Connect: CRACK TIP PLASTICITY AND FRACTURE INITIATION...

    Office of Scientific and Technical Information (OSTI)

    N50000* --Metals, Ceramics, & Other Materials; CRACKS; FRACTURE PROPERTIES; METALS BUILDING MATERIALSfracture of metal, crack tip plasticity and initiation criteria for;...

  20. Life prediction for bridged fatigue cracks

    SciTech Connect (OSTI)

    Cox, B.N.

    1994-08-01T23:59:59.000Z

    One of the more promising classes of composites touted for high temperature applications, and certainly the most available, is that of relatively brittle matrices, either ceramic or intermetallic, reinforced by strong, aligned, continuous fibers. Under cyclic loading in the fiber direction, these materials develop matrix cracks that often run perpendicular to the fibers, while the fibers remain intact in the crack wake, supplying bridging tractions across the fracture surfaces. The bridging tractions shield the crack tip from the applied load, dramatically reducing the crack velocity from that expected in an unreinforced material subjected to the same value, {Delta}K{sub a}, of the cyclic applied stress intensity factor. An important issue in reliability is the prediction of the growth rates of the bridged cracks. The growth rates of matrix fatigue cracks bridged by sliding fibers are now commonly predicted by models based on the micromechanics of frictional interfaces. However, there exist many reasons, both theoretical and experimental, for suspecting that the most popular micromechanical models are probably wrong in detail in the context of fatigue cracks. Furthermore, a review of crack growth data reveals that the validity of the micromechanics-based predictive model has never been tested and may never be tested. In this paper, two alternative approaches are suggested to the engineering problem of predicting the growth rates of bridged cracks without explicit recourse to micromechanics. Instead, it is shown that the material properties required to analyze bridging effects can be deduced directly from crack growth data. Some experiments are proposed to test the validity of the proposals.

  1. Delayed neutron emission measurements for U-235 and Pu-239

    E-Print Network [OSTI]

    Chen, Yong

    2009-05-15T23:59:59.000Z

    The delayed neutron emission rates of U-235 and Pu-239 samples were measured accurately from a thermal fission reaction. A Monte Carlo calculation using the Geant4 code was used to demonstrate the neutron energy independence of the detector used...

  2. Fundamentals of Delayed Coking Joint Industry Project

    SciTech Connect (OSTI)

    Michael Volk Jr; Keith Wisecarver

    2005-10-01T23:59:59.000Z

    Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking. The following deliverables are scheduled from the two projects of the three-year JIP: (1) A novel method for enhancing liquid yields from delayed cokers and data that provide insight as to the optimum temperature to remove hydrogen sulfide from furnace gases. (2) An understanding of what causes foaming in c

  3. Early stages in the development of stress corrosion cracks

    SciTech Connect (OSTI)

    Jones, R.H.; Simonen, E.P.

    1993-12-01T23:59:59.000Z

    Processes in growth of short cracks and stage I of long stress corrosion cracks were identified and evaluated. There is evidence that electrochemical effects can cause short stress corrosion cracks to grow at rates faster or slower than long cracks. Short cracks can grow at faster rates than long cracks for a salt film dissolution growth mechanism or from reduced oxygen inhibition of hydrolytic acidification. An increasing crack growth rate with increasing crack length could result from a process of increasing crack tip concentration of a critical anion, such as Cl{sup {minus}}, with increasing crack length in a system where the crack velocity is dependent on the Cl{sup {minus}} or some other anion concentration. An increasing potential drop between crack tip and mouth would result in an increased anion concentration at the crack tip and hence an increasing crack velocity. Stage I behavior of long cracks is another early development stage in the life of a stress corrosion crack which is poorly understood. This stage can be described by da/dt = AK{sup m} where da/dt is crack velocity, A is a constant, K is stress intensity and m ranges from 2 to 24 for a variety of materials and environments. Only the salt film dissolution model was found to quantitatively describe this stage; however, the model was only tested on one material and its general applicability is unknown.

  4. Modeling delay in genetic networks: From delay birth-death processes to delay stochastic differential equations

    SciTech Connect (OSTI)

    Gupta, Chinmaya; López, José Manuel; Azencott, Robert; Ott, William [Department of Mathematics, University of Houston, Houston, Texas 77004 (United States); Bennett, Matthew R. [Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77204, USA and Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77005 (United States); Josi?, Krešimir [Department of Mathematics, University of Houston, Houston, Texas 77004 (United States); Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204 (United States)

    2014-05-28T23:59:59.000Z

    Delay is an important and ubiquitous aspect of many biochemical processes. For example, delay plays a central role in the dynamics of genetic regulatory networks as it stems from the sequential assembly of first mRNA and then protein. Genetic regulatory networks are therefore frequently modeled as stochastic birth-death processes with delay. Here, we examine the relationship between delay birth-death processes and their appropriate approximating delay chemical Langevin equations. We prove a quantitative bound on the error between the pathwise realizations of these two processes. Our results hold for both fixed delay and distributed delay. Simulations demonstrate that the delay chemical Langevin approximation is accurate even at moderate system sizes. It captures dynamical features such as the oscillatory behavior in negative feedback circuits, cross-correlations between nodes in a network, and spatial and temporal information in two commonly studied motifs of metastability in biochemical systems. Overall, these results provide a foundation for using delay stochastic differential equations to approximate the dynamics of birth-death processes with delay.

  5. Understanding crack versus cavitation in pressure-sensitive adhesives: the role of kinetics

    E-Print Network [OSTI]

    Jérémie Teisseire; F. Nallet; P. Fabre; Cyprien Gay

    2006-09-18T23:59:59.000Z

    We perform traction experiments on viscous liquids highly confined between parallel plates, a geometry known as the probe-tack test in the adhesion community. Direct observation during the experiment coupled to force measurement shows the existence of several mechanisms for releasing the stress. Bubble nucleation and instantaneous growth had been observed in a previous work. Upon increasing further the traction velocity or the viscosity, the bubble growth is progressively delayed. At high velocities, cracks at the interface between the plate and the liquid appear before the bubbles have grown to their full size. Bubbles and cracks are thus observed concomitantly. At even higher velocities, cracks develop fully so early that the bubbles are not even visible. We present a theoretical model that describes these regimes, using a Maxwell fluid as a model for the actual fluid, a highly viscous silicon oil. We present the resulting phase diagramme for the different force peak regimes. The predictions are compatible with the data. Our results show that in addition to cavitation, interfacial cracks are encountered in a probe-tack traction test with viscoelastic, \\emph{liquid} materials and not solely with viscoelastic solids like adhesives.

  6. The Effects of Test Temperature, Temper, and Alloyed Copper on the Hydrogen-Controlled Crack Growth Rate of an Al-Zn-Mg-(Cu) Alloy

    SciTech Connect (OSTI)

    G.A. Young, Jr.; J.R. Scully

    2000-09-17T23:59:59.000Z

    The hydrogen embrittlement controlled stage II crack growth rate of AA 7050 (6.09 wt.% Zn, 2.14 wt% Mg, 2.19 wt.% Cu) was investigated as a function of temper and alloyed copper level in a humid air environment at various temperatures. Three tempers representing the underaged, peak aged, and overaged conditions were tested in 90% relative humidity (RH) air at temperatures between 25 and 90 C. At all test temperatures, an increased degree of aging (from underaged to overaged) produced slower stage II crack growth rates. The stage II crack growth rate of each alloy and temper displayed Arrhenius-type temperature dependence with activation energies between 58 and 99 kJ/mol. For both the normal copper and low copper alloys, the fracture path was predominantly intergranular at all test temperatures (25-90 C) in each temper investigated. Comparison of the stage II crack growth rates for normal (2.19 wt.%) and low (0.06 wt.%) copper alloys in the peak aged and overaged tempers showed the beneficial effect of copper additions on stage II crack growth rate in humid air. In the 2.19 wt.% copper alloy, the significant decrease ({approx} 10 times at 25 C) in stage II crack growth rate upon overaging is attributed to an increase in the apparent activation energy for crack growth. IN the 0.06 wt.% copper alloy, overaging did not increase the activation energy for crack growth but did lower the pre-exponential factor, {nu}{sub 0}, resulting in a modest ({approx} 2.5 times at 25 C) decrease in crack growth rate. These results indicate that alloyed copper and thermal aging affect the kinetic factors that govern stage II crack growth rate. Overaged, copper bearing alloys are not intrinsically immune to hydrogen environment assisted cracking but are more resistant due to an increased apparent activation energy for stage II crack growth.

  7. Catalytic cracking of residual petroleum fractions

    SciTech Connect (OSTI)

    Moore, H.F.; Mayo, S.L.; Goolsby, T.L. (Research and Development Dept., Ashland Petroleum Co., Ashland, KY (US))

    1991-01-01T23:59:59.000Z

    This paper reports on Arabian Light crude oil vacuum bottoms fractionated into five high-boiling fractions by wiped film evaporation, and the fractions subjected to catalytic cracking in a fixed-fluidized bed using a commercial equilibrium cracking catalyst. Density, aromaticity, and heteroatom content generally increased with boiling point, as did metals content except for vanadium and iron which demonstrated possible bimodal distributions. The cracking response of these fractions showed increasing yields of dry gas and coke, with decreasing gasoline yields, as a function of increasing apparent boiling point as would normally be expected. Surprisingly, however, local maxima were observed for wet gas yield and total conversion, with local minima for cycle oil and slurry yields, in the region of the 1200-1263{degrees}F (650-680{degrees}C) middle fraction. All fractions showed significant response to cracking, with coke yields generally being the only negative factor observed.

  8. Parallel interacting edge cracks under pure bending

    E-Print Network [OSTI]

    Moran, Ivan

    1991-01-01T23:59:59.000Z

    . Once the applicability of the Williams' equations, have been proved or disproved, the power of the singularity represented by the first term of equation 1. 1 and the polynomial expansion can be truncated in order to extract information... of Williams' approach for the case of cracked bodies under pure bending is demonstrated. Four point bending load is applied on specimens with either a vertical or a slant crack giving Mode I or Mixed Mode I ? II respectively. The existence...

  9. Studies on fruit cracking of tomatoes

    E-Print Network [OSTI]

    Cotner, Sam Don

    1966-01-01T23:59:59.000Z

    STUDIES ON FRUIT CRACKING OF TOMATOES A Thesis Sam Don Cotner Submitted to the Graduate College of' ths Texas A&M University in partial fulfillment of the requirements i' or the degree of MASTER OF SCIENCE January~ 1966 Major Subject...: Horticulture STUDlES ON FRUIT CRACKING OF TOMATOES A Thesis Sam Dcn Cotnsr Approved as to style and content by; (Chairman of tes Member (Head o Department) mbsr) January 1966 TABLE OF CONTENTS Chapter I. INTRODUCTION . II. REVIEW OF LITERATURE Page...

  10. An investigation of penetrant techniques for detection of machining-induced surface-breaking cracks on monolithic ceramics

    SciTech Connect (OSTI)

    Forster, G.A.; Ellingson, W.A.

    1996-02-01T23:59:59.000Z

    The purpose of this effort was to evaluate penetrant methods for their ability to detect surface-breaking cracks in monolithic ceramic materials with an emphasis on detection of cracks generated by machining. There are two basic penetrant types, visible and fluorescent. The visible penetrant method is usually augmented by powder developers and cracks detected can be seen in visible light. Cracks detected by fluorescent penetrant are visible only under ultraviolet light used with or without a developer. The developer is basically a powder that wicks up penetrant from a crack to make it more observable. Although fluorescent penetrants were recommended in the literature survey conducted early in this effort, visible penetrants and two non-standard techniques, a capillary gaseous diffusion method under development at the institute of Chemical Physics in Moscow, and the {open_quotes}statiflux{close_quotes} method which involves use of electrically charged particles, were also investigated. SiAlON ring specimens (1 in. diameter, 3/4 in. wide) which had been subjected to different thermal-shock cycles were used for these tests. The capillary gaseous diffusion method is based on ammonia; the detector is a specially impregnated paper much like litmus paper. As expected, visible dye penetrants offered no detection sensitivity for tight, surface-breaking cracks in ceramics. Although the non-standard statiflux method showed promise on high-crack-density specimens, it was ineffective on limited-crack-density specimens. The fluorescent penetrant method was superior for surface-breaking crack detection, but successful application of this procedure depends greatly on the skill of the user. Two presently available high-sensitivity fluorescent penetrants were then evaluated for detection of microcracks on Si{sub 3}N{sub 4} and SiC from different suppliers. Although 50X optical magnification may be sufficient for many applications, 200X magnification provides excellent delectability.

  11. Recent evaluations of crack-opening-area in circumferentially cracked pipes

    SciTech Connect (OSTI)

    Rahman, S.; Brust, F.; Ghadiali, N.; Wilkowski, G.; Miura, N.

    1997-04-01T23:59:59.000Z

    Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. The leak rates depend on the crack-opening area of the through-wall crack in the pipe. In addition to LBB analyses which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessing temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section XI. The objectives of this study were to review, evaluate, and refine current predictive models for performing crack-opening-area analyses of circumferentially cracked pipes. The results from twenty-five full-scale pipe fracture experiments, conducted in the Degraded Piping Program, the International Piping Integrity Research Group Program, and the Short Cracks in Piping and Piping Welds Program, were used to verify the analytical models. Standard statistical analyses were performed to assess used to verify the analytical models. Standard statistical analyses were performed to assess quantitatively the accuracy of the predictive models. The evaluation also involved finite element analyses for determining the crack-opening profile often needed to perform leak-rate calculations.

  12. TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

    SciTech Connect (OSTI)

    Langton, C.

    2012-05-11T23:59:59.000Z

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  13. The analysis of cracks in high-pressure piping and their effects on strength and lifetime of construction components at the Ignalina nuclear plant

    SciTech Connect (OSTI)

    Aleev, A.; Petkevicius, K.; Senkus, V. [and others

    1997-04-01T23:59:59.000Z

    A number of cracks and damages of other sorts have been identified in the high-pressure parts at the Ignalina Nuclear Plant. They are caused by inadequate production- and repair technologies, as well as by thermal, chemical and mechanical processes of their performance. Several techniques are available as predictions of cracks and other defects of pressurized vessels. The choice of an experimental technique should be based on the level of its agreement with the actual processes.

  14. Thermal Fluids

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Thermal Fluids The Thermal Fluids and Heat Transfer program works on thermal hydraulic reactor safety code development and experimental heat transferthermal hydraulics. The...

  15. Characterization of geothermal reservoir crack patterns using...

    Open Energy Info (EERE)

    directions. From the polarizations the authors estimated three predominant subsurface fracture directions, and from the time delays of the split waves they determined...

  16. E-Print Network 3.0 - axially cracked pressure Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Collection: Engineering 2 MATERIAL POINT METHOD CALCULATIONS WITH EXPLICIT CRACKS, FRACTURE PARAMETERS, AND CRACK Summary: under axial impact with a crack in the central disk....

  17. E-Print Network 3.0 - anomolous fatigue crack Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Science ; Engineering 6 Cracking Resistance of Asphalt Rubber Mix Versus Summary: vs. Fracture Mechanics Conventional Fatigue Testing Crack initiation Fracture Mechanics Crack......

  18. Gels under stress: the origins of delayed collapse

    E-Print Network [OSTI]

    Lisa J. Teece; James M. Hart; Kerry Yen Ni Hsu; Stephen Gilligan; Malcolm A. Faers; Paul Bartlett

    2014-03-12T23:59:59.000Z

    Attractive colloidal particles can form a disordered elastic solid or gel when quenched into a two-phase region, if the volume fraction is sufficiently large. When the interactions are comparable to thermal energies the stress-bearing network within the gel restructures over time as individual particle bonds break and reform. Typically, under gravity such weak gels show a prolonged period of either no or very slow settling, followed by a sudden and rapid collapse - a phenomenon known as delayed collapse. The link between local bond breaking events and the macroscopic process of delayed collapse is not well understood. Here we summarize the main features of delayed collapse and discuss the microscopic processes which cause it. We present a plausible model which connects the kinetics of bond breaking to gel collapse and test the model by exploring the effect of an applied external force on the stability of a gel.

  19. Linking Grain Boundary Microstructure to Stress Corrosion Cracking of Cold Rolled Alloy 690 in PWR Primary Water

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Olszta, Matthew J.; Toloczko, Mychailo B.; Thomas, Larry E.

    2012-10-01T23:59:59.000Z

    Grain boundary microstructures and microchemistries are examined in cold-rolled alloy 690 tubing and plate materials and comparisons are made to intergranular stress corrosion cracking (IGSCC) behavior in PWR primary water. Chromium carbide precipitation is found to be a key aspect for materials in both the mill annealed and thermally treated conditions. Cold rolling to high levels of reduction was discovered to produce small IG voids and cracked carbides in alloys with a high density of grain boundary carbides. The degree of permanent grain boundary damage from cold rolling was found to depend directly on the initial IG carbide distribution. For the same degree of cold rolling, alloys with few IG precipitates exhibited much less permanent damage. Although this difference in grain boundary damage appears to correlate with measured SCC growth rates, crack tip examinations reveal that cracked carbides appeared to blunt propagation of IGSCC cracks in many cases. Preliminary results suggest that the localized grain boundary strains and stresses produced during cold rolling promote IGSCC susceptibility and not the cracked carbides and voids.

  20. Environmentally assisted cracking of LWR materials.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Kassner, T. F.; Park, J. H.; Shack, W. J.; Zhang, J.; Brust, F. W.; Dong, P.

    1997-12-05T23:59:59.000Z

    The effect of dissolved oxygen level on fatigue life of austenitic stainless steels is discussed and the results of a detailed study of the effect of the environment on the growth of cracks during fatigue initiation are presented. Initial test results are given for specimens irradiated in the Halden reactor. Impurities introduced by shielded metal arc welding that may affect susceptibility to stress corrosion cracking are described. Results of calculations of residual stresses in core shroud weldments are summarized. Crack growth rates of high-nickel alloys under cyclic loading with R ratios from 0.2-0.95 in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320 C are summarized.

  1. Crack detection using resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, A.; Bell, T.M.; Rhodes, G.W.

    1994-10-04T23:59:59.000Z

    Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component. 5 figs.

  2. Crack detection using resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, Albert (Santa Fe, NM); Bell, Thomas M. (Santa Fe, NM); Rhodes, George W. (Albuquerque, NM)

    1994-01-01T23:59:59.000Z

    Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component.

  3. Fast electromigration crack in nanoscale aluminum film

    SciTech Connect (OSTI)

    Emelyanov, O. A., E-mail: oaemel2@gmail.com; Ivanov, I. O. [St. Petersburg State Polytechnical University, Saint-Petersburg (Russian Federation)

    2014-08-14T23:59:59.000Z

    The current-induced breakage of 20?nm thin aluminum layers deposited onto capacitor grade polypropylene (PP) films is experimentally studied. Biexponential current pulses of different amplitude (10–15?A) and duration (0.1–1??s) were applied to the samples. Breakage occurred after fast development of electromigrating ?200?nm-wide cracks with initial propagation velocity of ?1?m/s under a high current density of ?10{sup 12?}A/m{sup 2}. The cracks stopped when their lengths reached 250–450??m. This behavior is explained by the balance of electromigration and stress-induced atomic fluxes.

  4. Effects of restraint on expansion due to delayed ettringite formation

    SciTech Connect (OSTI)

    Bouzabata, Hassina [Universite de Toulouse, UPS, INSA, LMDC (Laboratoire Materiaux et Durabilite des Constructions), 135, avenue de Rangueil, F-31 077 Toulouse Cedex 04 (France); Laboratoire Materiaux et Durabilite des Constructions, Department of Civil Engineering, University of Constantine (Algeria); Multon, Stephane, E-mail: multon@insa-toulouse.fr [Universite de Toulouse, UPS, INSA, LMDC (Laboratoire Materiaux et Durabilite des Constructions), 135, avenue de Rangueil, F-31 077 Toulouse Cedex 04 (France); Sellier, Alain [Universite de Toulouse, UPS, INSA, LMDC (Laboratoire Materiaux et Durabilite des Constructions), 135, avenue de Rangueil, F-31 077 Toulouse Cedex 04 (France); Houari, Hacene [Laboratoire Materiaux et Durabilite des Constructions, Department of Civil Engineering, University of Constantine (Algeria)

    2012-07-15T23:59:59.000Z

    Delayed ettringite formation (DEF) is a chemical reaction that causes expansion in civil engineering structures. The safety level of such damaged structures has to be reassessed. To do this, the mechanical conditions acting on DEF expansions have to be analysed and, in particular, the variation of strength with expansion and the effect of restraint on the DEF expansion. This paper highlights several points: DEF expansion is isotropic in stress-free conditions, compressive stresses decrease DEF expansion in the direction subjected to restraint and lead to cracks parallel to the restraint, and expansion measured in the stress-free direction of restrained specimens is not modified. Thus restraint causes a decrease of the volumetric expansion and DEF expansion under restraint is anisotropic. Moreover, the paper examines the correlation between DEF expansion and concrete damage, providing data that can be used for the quantification of the effect of stresses on DEF induced expansion.

  5. Interim Report on Thermal Cycling Model Development for Representative Unisolable Piping Configurations (MRP-81)

    SciTech Connect (OSTI)

    J. Keller, A. Bilanin

    2002-11-30T23:59:59.000Z

    Thermal fatigue can lead to cracking in dead-ended branch lines attached to PWR primary coolant piping. This interim report describes the results of on-going research to provide an improved screening tool for identification of susceptible piping.

  6. Crack closure effects on fatigue crack growth thresholds and remaining life in an HSLA steel

    SciTech Connect (OSTI)

    Todd, J.A.; Mostovoy, S. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Mechanical, Materials and Aerospace Engineering; Chen, L. [Texas Instruments, Attleboro, MA (United States); Yankov, E.Y. [A. Finkl and Sons, Chicago, IL (United States)

    1997-02-01T23:59:59.000Z

    The effects of crack closure on the near-threshold corrosion fatigue crack growth behavior of Mil S-24645 HSLA steel and its weld metal have been investigated in air, ASTM seawater at the free corrosion potential, and ASTM seawater at {minus}0.8V and {minus}1.0V (SCE) using frequencies of 10, 2, and 0.2 Hz, and a stress ratio, R = 0.1. Remaining life, in the presence and absence of crack closure, has been estimated as a function of applied stress range for a structure containing a 3-mm-deep surface semi-elliptical flaw.

  7. Environmentally assisted cracking in Light Water Reactors: Semiannual report, April 1993--September 1993. Volume 17

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Karlsen, T.; Kassner, T.F.; Michaud, W.F.; Ruther, W.E.; Sanecki, J.E.; Shack, W.J.; Soppet, W.K. [Argonne National Lab., IL (United States)

    1994-06-01T23:59:59.000Z

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRS) during the six months from April 1993 to September 1993. EAC and fatigue of piping, pressure vessels, and core components in LWRs are important concerns as extended reactor lifetimes are envisaged. Topics that have been investigated include (a) fatigue of low-alloy steel used in piping, steam generators, and reactor pressure vessels; (b) EAC of cast stainless steels (SSs); and (c) radiation-induced segregation and irradiation-assisted stress corrosion cracking of Type 304 SS after accumulation of relatively high fluence. Fatigue tests were conducted on medium-sulfur-content A106-Gr B piping and A533-Gr B pressure vessel steels in simulated PWR water and in air. Additional crack growth data were obtained on fracture-mechanics specimens of cast austenitic SSs in the as-received and thermally aged conditions in simulated boiling-water reactor (BWR) water at 289{degree}C. The data were compared with predictions based on crack growth correlations for wrought austenitic SS in oxygenated water developed at ANL and rates in air from Section 11 of the ASME Code. Microchemical and microstructural changes in high- and commercial-purity Type 304 SS specimens from control-blade absorber tubes and a control-blade sheath from operating BWRs were studied by Auger electron spectroscopy and scanning electron microscopy.

  8. Grain Boundary Structure Effects on Intergranular Stress Corrosion Cracking of

    E-Print Network [OSTI]

    Olson, Tamara

    Grain Boundary Structure Effects on Intergranular Stress Corrosion Cracking of Alloy X­750 Y. Pan B­of­freedom) and correlations with intergranular stress corrosion cracking observed in Alloy X­750. Orientation imaging

  9. Reflective Cracking Study: HVS Test Section Forensic Investigation

    E-Print Network [OSTI]

    Jones, David; Steven, B.; Harvey, John T

    2008-01-01T23:59:59.000Z

    the asphalt concrete. Summary of Testing on the Underlyingtesting performed to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete.concrete. It describes the forensic investigation of the HVS rutting and reflective cracking testing

  10. Evaluation of the delayed neutron characteristic for transmutation of the high-level waste using fast reactor technology

    SciTech Connect (OSTI)

    Ignatjev, S.V. [State Scientific Centre of Russian Federation, Obninsk (Russian Federation). Inst. of Physics and Power Engineering

    1995-12-31T23:59:59.000Z

    The method for evaluation of delayed fission neutron time and energy distributions is proposed. The method is tested for the case of U-235 thermal fission and used for Pu-238, Am-241, and Np-237 fission by the fast reactor spectrum neutrons. In the last case new data on different types of the delayed neutron spectra have been obtained.

  11. Environmentally assisted cracking in light water reactors

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Gruber, E.E. [and others

    1996-07-01T23:59:59.000Z

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from April 1995 to December 1995. Topics that have been investigated include fatigue of carbon and low-alloy steel used in reactor piping and pressure vessels, EAC of Alloy 600 and 690, and irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS. Fatigue tests were conducted on ferritic steels in water that contained various concentrations of dissolved oxygen (DO) to determine whether a slow strain rate applied during different portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Crack-growth-rate tests were conducted on compact-tension specimens from several heats of Alloys 600 and 690 in simulated LWR environments. Effects of fluoride-ion contamination on susceptibility to intergranular cracking of high- and commercial- purity Type 304 SS specimens from control-tensile tests at 288 degrees Centigrade. Microchemical changes in the specimens were studied by Auger electron spectroscopy and scanning electron microscopy to determine whether trace impurity elements may contribute to IASCC of these materials.

  12. Digital radiographic systems detect boiler tube cracks

    SciTech Connect (OSTI)

    Walker, S. [EPRI, Charlotte, NC (United States)

    2008-06-15T23:59:59.000Z

    Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.

  13. CRACKING OF PIc NUCLEAR CONTAINMENT STRUCTURES

    E-Print Network [OSTI]

    CRACKING OF PIc NUCLEAR CONTAINMENT STRUCTURES By Sami H. Rizkalla,l Sidney H. Simmonds': and James structures for some Canadian nuclear reactors consist of a heavy concrete base, a cylindrical wall, a ring the design accident pressure. This would result in the walls and dome of the containment being stressed

  14. NORTHWESTERN UNIVERSITY Autonomous Crack Comparometer Phase II

    E-Print Network [OSTI]

    program between the two universities. Thanks are also given to the staff of the Infrastructure Technology Institute and in particular Dan Marron for all his advice and assistance during the project. I would like that daily and weekly weather related crack displacements are greater than those produced by dynamic events

  15. Stress corrosion cracking and crack tip characterization of Alloy X-750 in light water reactor environments

    E-Print Network [OSTI]

    Gibbs, Jonathan Paul

    2011-01-01T23:59:59.000Z

    Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288°C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

  16. Stress Corrosion Cracking and Crack Tip Characterization of Alloy X-750 in Light Water Reactor Environments

    E-Print Network [OSTI]

    Gibbs, Jonathan Paul

    Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288°C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

  17. Enhanced ultrasonic detection of fatigue cracks by laser-induced crack closure

    E-Print Network [OSTI]

    Nagy, Peter B.

    , corrosion, etc. . Sec- ond, it is important to distinguish small fatigue cracks as early as possible after threshold in aluminum, aluminum­ lithium, and titanium alloys.1 For example, extensive multiple-site fatigue

  18. CRACK STATISTIC OF CRYSTALLINE SILICON PHOTOVOLTAIC MODULES M. Kntges1

    E-Print Network [OSTI]

    the risk of cracks, as well as for statistical power loss assessment. Keywords: PV module, micro cracks separation, thus resulting in inactive cell parts. For this special case a clear assessment of the power loss this gap and provide a first statistic of cracks in PV modules for future power loss assessment

  19. Characterization of cracking restraint at sawcut joints using the German Cracking Frame

    E-Print Network [OSTI]

    Vepakomma, Shilpa

    2002-01-01T23:59:59.000Z

    . . 7 Percentage cracks vs. time aAer placement in bike trail concrete. . . , . . . . . . 8. Development of cracking stress and strength vs. time atter placement of bike trail concrete 9. Equivalent temperature difference (between the slab top... and bottom) vs. time after placement in the bike trail concrete. . . . . . . . . . . . . , , . . . . . . . . 10, Relative humidity at 0. 75 inches below surface vs. time after placement for the bike trail concrete 11. Calculated shrinkage vs. time aAer...

  20. UWB delay and multiply receiver

    DOE Patents [OSTI]

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Romero, Carlos E.

    2013-09-10T23:59:59.000Z

    An ultra-wideband (UWB) delay and multiply receiver is formed of a receive antenna; a variable gain attenuator connected to the receive antenna; a signal splitter connected to the variable gain attenuator; a multiplier having one input connected to an undelayed signal from the signal splitter and another input connected to a delayed signal from the signal splitter, the delay between the splitter signals being equal to the spacing between pulses from a transmitter whose pulses are being received by the receive antenna; a peak detection circuit connected to the output of the multiplier and connected to the variable gain attenuator to control the variable gain attenuator to maintain a constant amplitude output from the multiplier; and a digital output circuit connected to the output of the multiplier.

  1. Delayed neutrons as a probe of nuclear charge distribution in fission of heavy nuclei by neutrons

    E-Print Network [OSTI]

    Isaev, S G; Piksaikin, V M; Roshchenko, V A

    2001-01-01T23:59:59.000Z

    A method of the determination of cumulative yields of delayed neutron precursors is developed. This method is based on the iterative least-square procedure applied to delayed neutron decay curves measured after irradiation of sup 2 sup 3 sup 5 U sample by thermal neutrons. Obtained cumulative yields in turns were used for deriving the values of the most probable charge in low-energy fission of the above-mentioned nucleus.

  2. Why Do Kraft Recovery Boiler Composite Floor Tubes Crack?

    SciTech Connect (OSTI)

    Keiser, J.R.

    2001-10-22T23:59:59.000Z

    Cracks were first reported in 1992 in co-extruded 304L stainless steel/SA210 Gd Al carbon steel floor tubes of North American black liquor recovery boilers. Since then, a considerable amount of information has been collected on the tube environment, crack characteristics, the stress state of the tubes, and the crack initiation and propagation mechanisms. These studies have identified both operating procedures that apparently can greatly lessen the likelihood of crack formation in the stainless steel layer and alternate materials that appear to be much more resistant to cracking than is 304L stainless.

  3. Stress corrosion cracking behavior of Alloy 600 in high temperature water

    SciTech Connect (OSTI)

    Webb, G.L.; Burke, M.G.

    1995-07-01T23:59:59.000Z

    SCC susceptibility of Alloy 600 in deaerated water at 360 C (statically loaded U-bend specimens) is dependent on microstructure and whether the material was cold-worked and annealed (CWA) or hot-worked and annealed (HWA). All cracking was intergranular, and materials lacking grain boundary carbides were most susceptible to SCC initiation. CWA tubing materials are more susceptible to SCC initiation than HWA ring-rolled forging materials with similar microstructures (optical metallography). In CWA tubing materials, one crack dominated and grew to a visible size. HWA materials with a low hot-working finishing temperature (<925 C) and final anneals at 1010-1065 C developed both large cracks (similar to those in CWA materials) and small intergranular microcracks detectable only by destructive metallography. HWA materials with a high hot-working finishing temperature (>980 C) and a high-temperature final anneal (>1040 C), with grain boundaries that are fully decorated, developed only microcracks in all specimens. These materials did not develop large, visually detectable cracks, even after more than 300 weeks exposure. A low-temperature thermal treatment (610 C for 7h), which reduces or eliminates SCC in Alloy 600, did not eliminate microcrack formation in high temperature processed HWA materials. Conventional metallographic and analytical electron microscopy (AEM) were done on selected materials to identify the factors responsible for the observed differences in cracking behavior. Major difference between high-temperature HWA and low-temperature HWA and CWA materials was that the high temperature processing and final annealing produced predominantly ``semi-continuous`` dendritic M{sub 7}C{sub 3} carbides along grain boundaries with a minimal amount of intragranular carbides. Lower temperature processing produced intragranular M7C3 carbides, with less intergranular carbides.

  4. Heavy-Section Steel Technology Program: Recent developments in crack initiation and arrest research

    SciTech Connect (OSTI)

    Pennell, W.E.

    1991-01-01T23:59:59.000Z

    Technology for the analysis of crack initiation and arrest is central to the reactor pressure vessel fracture-margin-assessment process. Regulatory procedures for nuclear plants utilize this technology to assure the retention of adequate fracture-prevention margins throughout the plant operating license period. As nuclear plants age and regulatory procedures dictate that fracture-margin assessments be performed, interest in the fracture-mechanics technology incorporated into those procedures has heightened. This has led to proposals from a number of sources for development and refinement of the underlying crack-initiation and arrest-analysis technology. This paper presents an overview of ongoing Heavy-Section Steel Technology (HSST) Program research aimed at refining the fracture toughness data used in the analysis of fracture margins under pressurized-thermal-shock loading conditions. 33 refs., 13 figs.

  5. Soil cracking modelling using the mesh-free SPH method

    E-Print Network [OSTI]

    Bui, H H; Kodikara, J; Sanchez, M

    2015-01-01T23:59:59.000Z

    The presence of desiccation cracks in soils can significantly alter their mechanical and hydrological properties. In many circumstances, desiccation cracking in soils can cause significant damage to earthen or soil supported structures. For example, desiccation cracks can act as the preference path way for water flow, which can facilitate seepage flow causing internal erosion inside earth structures. Desiccation cracks can also trigger slope failures and landslides. Therefore, developing a computational procedure to predict desiccation cracking behaviour in soils is vital for dealing with key issues relevant to a range of applications in geotechnical and geo-environment engineering. In this paper, the smoothed particle hydrodynamics (SPH) method will be extended for the first time to simulate shrinkage-induced soil cracking. The main objective of this work is to examine the performance of the proposed numerical approach in simulating the strong discontinuity in material behaviour and to learn about the crack ...

  6. Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking

    SciTech Connect (OSTI)

    Das, Subodh K.

    2006-01-09T23:59:59.000Z

    A successful four-year project on the modeling and optimization of direct chill (DC) casting to reduce ingot cracking has been completed. The project involved close collaboration among private industries, national laboratories, and universities. During the four-year project, 16 quarterly meetings brought the industrial partners and the research team together for discussion of research results and research direction. The industrial partners provided guidance, facilities, and experience to the research team. The research team went to two industrial plants to measure temperature distributions in commercial 60,000-lb DC casting ingot. The collaborative research resulted in several major accomplishments or findings: (1) Surface cracks were shown to be a result of hot tearing rather than cold cracks, as was thought before this project. These cracks form on the surface of a DC cast ingot just above the impingement point of the secondary cooling water jets. The cracks form along dendrite and grain boundaries, where solute and impurity elements are highly segregated. This understanding led to the development of a new technique for determining the mechanical properties in the nonequilibrium mushy zone of alloys and to thermodynamic predictions of the hot tearing propensity of DC cast ingots. (2) The apparent heat transfer coefficient (HTC) at the ingot surface in the water cooling region during DC casting was determined on the basis of temperature measurements in commercial DC casting ingots and an inverse heat transfer analysis. HTCs were calculated as a function of temperature and time, and covered the different regimes of heat transfer expected during DC casting. The calculated values were extrapolated to include the effect of water flow rate. The calculated HTCs had a peak at around 200 C, corresponding to the high heat transfer rates during nucleate boiling, and the profile was consistent with similar data published in the literature. (3) A new method, termed the reheating-cooling method (RCM), was developed and validated for measuring mechanical properties in the nonequilibrium mushy zones of alloys. The new method captures the brittle nature of aluminum alloys at temperatures close to the nonequilibrium solidus temperature, while specimens tested using the reheating method exhibit significant ductility. The RCM has been used for determining the mechanical properties of alloys at nonequilibrium mushy zone temperatures. Accurate data obtained during this project show that the metal becomes more brittle at high temperatures and high strain rates. (4) The elevated-temperature mechanical properties of the alloy were determined. Constitutive models relating the stress and strain relationship at elevated temperatures were also developed. The experimental data fit the model well. (5) An integrated 3D DC casting model has been used to simulate heat transfer, fluid flow, solidification, and thermally induced stress-strain during casting. A temperature-dependent HTC between the cooling water and the ingot surface, cooling water flow rate, and air gap were coupled in this model. An elasto-viscoplastic model based on high-temperature mechanical testing was used to calculate the stress during casting. The 3D integrated model can be used for the prediction of temperature, fluid flow, stress, and strain distribution in DC cast ingots. (6) The cracking propensity of DC cast ingots can be predicted using the 3D integrated model as well as thermodynamic models. Thus, an ingot cracking index based on the ratio of local stress to local alloy strength was established. Simulation results indicate that cracking propensity increases with increasing casting speed. The composition of the ingots also has a major effect on cracking formation. It was found that copper and zinc increase the cracking propensity of DC cast ingots. The goal of this Aluminum Industry of the Future (IOF) project was to assist the aluminum industry in reducing the incidence of stress cracks in DC castings from a current level of 5% down to 2%. This could lead to energy savings

  7. The Stress Corrosion Crack Growth Rate of Alloy 600 Heat Affected Zones Exposed to High Purity Water

    SciTech Connect (OSTI)

    George A. Young; Nathan Lewis

    2003-04-05T23:59:59.000Z

    Grain boundary chromium carbides improve the resistance of nickel based alloys to primary water stress corrosion cracking (PWSCC). However, in weld heat affected zones (HAZ's), thermal cycles from fusion welding can solutionize beneficial grain boundary carbides, produce locally high residual stresses and strains, and promote PWSCC. The present research investigates the crack growth rate of an A600 HAZ as a function of test temperature. The A600 HAZ was fabricated by building up a gas-tungsten-arc-weld deposit of EN82H filler metal onto a mill-annealed A600 plate. Fracture mechanics based, stress corrosion crack growth rate testing was performed in high purity water between 600 F and 680 F at an initial stress intensity factor of 40 ksi {radical}in and at a constant electrochemical potential. The HAZ samples exhibited significant SCC, entirely within the HAZ at all temperatures tested. While the HAZ samples showed the same temperature dependence for SCC as the base material (HAZ: 29.8 {+-} 11.2{sub 95%} kcal/mol vs A600 Base: 35.3 {+-} 2.58{sub 95%} kcal/mol), the crack growth rates were {approx} 30X faster than the A600 base material tested at the same conditions. The increased crack growth rates of the HAZ is attributed to fewer intergranular chromium rich carbides and to increased plastic strain in the HAZ as compared to the unaffected base material.

  8. SCREENING TESTS FOR IMPROVED METHANE CRACKING MATERIALS

    SciTech Connect (OSTI)

    Klein, J; Jeffrey Holder, J

    2007-07-16T23:59:59.000Z

    Bench scale (1 to 6 gram) methane cracking tests have been performed on a variety of pure elements, some alloys, and SAES{reg_sign} commercial getters St 101, St 198, St 707, St 737, and St 909 to determine methane cracking performance (MCP) of 5% methane in a helium carrier at 700 C, 101.3 kPa (760 torr) with a 10 sccm feed. The MCP was almost absent from some materials tested while others showed varying degrees of MCP. Re, Cr, V, Gd, and Mo powders had good MCP, but limited capacities. Nickel supported on kieselguhr (Ni/k), a Zr-Ni alloy, and the SAES{reg_sign} getters had good MCP in a helium carrier. The MCP of these same materials was suppressed in a hydrogen carrier stream and the MCP of the Zr-based materials was reduced by nitride formation when tested with a nitrogen carrier gas.

  9. Fluid catalytic cracking of heavy petroleum fractions

    SciTech Connect (OSTI)

    McHenry, K.W.

    1981-06-30T23:59:59.000Z

    A process is claimed for fluid catalytic cracking of residuum and other heavy oils comprising of gas oil, petroleum residue, reduced and whole crudes and shale oil to produce gasoline and other liquid products which are separated in various streams in a fractionator and associated vapor recovery equipment. The heat from combustion of coke on the coked catalyst is removed by reacting sulfur-containing coke deposits with steam and oxygen in a separate stripper-gasifier to produce a low btu gas stream comprising of sulfur compounds, methane, carbon monoxide, hydrogen, and carbon dioxide at a temperature of from about 1100/sup 0/F. To about 2200/sup 0/F. The partially regenerated catalyst then undergoes complete carbon removal in a regeneration vessel. The regenerated catalyst is recycled for re-use in the cracking of heavy petroleum fractions. The liquid products are gasoline, distillates, heavy fuel oil, and light hydrocarbons.

  10. Circumferential cracking of steam generator tubes

    SciTech Connect (OSTI)

    Karwoski, K.J.

    1997-04-01T23:59:59.000Z

    On April 28, 1995, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 95-03, {open_quote}Circumferential Cracking of Steam Generator Tubes.{close_quote} GL 95-03 was issued to obtain information needed to verify licensee compliance with existing regulatory requirements regarding the integrity of steam generator tubes in domestic pressurized-water reactors (PWRs). This report briefly describes the design and function of domestic steam generators and summarizes the staff`s assessment of the responses to GL 95-03. The report concludes with several observations related to steam generator operating experience. This report is intended to be representative of significant operating experience pertaining to circumferential cracking of steam generator tubes from April 1995 through December 1996. Operating experience prior to April 1995 is discussed throughout the report, as necessary, for completeness.

  11. Process for magnetic beneficiating petroleum cracking catalyst

    DOE Patents [OSTI]

    Doctor, Richard D. (Lisle, IL)

    1993-01-01T23:59:59.000Z

    A process for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded.

  12. Process for magnetic beneficiating petroleum cracking catalyst

    DOE Patents [OSTI]

    Doctor, R.D.

    1993-10-05T23:59:59.000Z

    A process is described for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded. 1 figures.

  13. Delayed Neutron and Delayed Photon Characteristics from Photofission of Actinides

    SciTech Connect (OSTI)

    Dore, D.; Berthoumieux, E.; Leprince, A.; Ridikas, D. [DSM/IRFUS/PhN, CEA/Saclay, Gif-sur-Yvette, F-91191 (France); Ledoux, X. [CEA/DAM/DIF, Arpajon, F-91297 (France); Agelou, M.; Carrel, F.; Gmar, M. [CEA, LIST, Gif-sur-Yvette, F-91191 (France)

    2011-12-13T23:59:59.000Z

    Delayed neutron (DN) and delayed photon (DP) emissions from photofission reactions play an important role for applications involving nuclear material detection and characterization. To provide new, accurate, basic nuclear data for evaluations and data libraries, an experimental programme of DN and DP measurements has been undertaken for actinides with bremsstrahlung endpoint energy in the giant resonance region ({approx}15 MeV). In this paper, the experimental setup and the data analysis method will be described. Experimental results for DN and DP characteristics will be presented for {sup 232}Th, {sup 235,238}U, {sup 237}Np, and {sup 239}Pu. Finally, an example of an application to study the contents of nuclear waste packages will be briefly discussed.

  14. Structures for dense, crack free thin films

    DOE Patents [OSTI]

    Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

    2011-03-08T23:59:59.000Z

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  15. CDF central preshower and crack detector upgrade

    SciTech Connect (OSTI)

    Artikov, A.; Boudagov, J.; Chokheli, D.; Drake, G.; Gallinaro, M.; Giunta, M.; Grudzinski, J.; Huston, J.; Iori, M.; Kim, D.; Kim, M.; /Dubna, JINR /Argonne /Rockefeller

    2007-02-01T23:59:59.000Z

    The CDF Central Preshower and Crack Detector Upgrade consist of scintillator tiles with embedded wavelength-shifting fibers, clear-fiber optical cables, and multi-anode photomultiplier readout. A description of the detector design, test results from R&D studies, and construction phase are reported. The upgrade was installed late in 2004, and a large amount of proton-antiproton collider data has been collected since then. Detector studies using those data are also discussed.

  16. High Quality Compact Delay Test Generation

    E-Print Network [OSTI]

    Wang, Zheng

    2011-08-08T23:59:59.000Z

    Delay testing is used to detect timing defects and ensure that a circuit meets its timing specifications. The growing need for delay testing is a result of the advances in deep submicron (DSM) semiconductor technology and the increase in clock...

  17. Creep and Creep-Fatigue Crack Growth at Structural Discontinuities and Welds

    SciTech Connect (OSTI)

    Dr. F. W. Brust; Dr. G. M. Wilkowski; Dr. P. Krishnaswamy; Mr. Keith Wichman

    2010-01-27T23:59:59.000Z

    The subsection ASME NH high temperature design procedure does not admit crack-like defects into the structural components. The US NRC identified the lack of treatment of crack growth within NH as a limitation of the code and thus this effort was undertaken. This effort is broken into two parts. Part 1, summarized here, involved examining all high temperature creep-fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within NH. The second part of this task, which has just started, is to develop design rules for possible implementation within NH. This second part is a challenge since all codes require step-by-step analysis procedures to be undertaken in order to assess the crack growth and life of the component. Simple rules for design do not exist in any code at present. The codes examined in this effort included R5, RCC-MR (A16), BS 7910, API 579, and ATK (and some lesser known codes). There are several reasons that the capability for assessing cracks in high temperature nuclear components is desirable. These include: (1) Some components that are part of GEN IV reactors may have geometries that have sharp corners - which are essentially cracks. Design of these components within the traditional ASME NH procedure is quite challenging. It is natural to ensure adequate life design by modeling these features as cracks within a creep-fatigue crack growth procedure. (2) Workmanship flaws in welds sometimes occur and are accepted in some ASME code sections. It can be convenient to consider these as flaws when making a design life assessment. (3) Non-destructive Evaluation (NDE) and inspection methods after fabrication are limited in the size of the crack or flaw that can be detected. It is often convenient to perform a life assessment using a flaw of a size that represents the maximum size that can elude detection. (4) Flaws that are observed using in-service detection methods often need to be addressed as plants age. Shutdown inspection intervals can only be designed using creep and creep-fatigue crack growth techniques. (5) The use of crack growth procedures can aid in examining the seriousness of creep damage in structural components. How cracks grow can be used to assess margins on components and lead to further safe operation. After examining the pros and cons of all these methods, the R5 code was chosen as the most up-to-date and validated high temperature creep and creep fatigue code currently used in the world at present. R5 is considered the leader because the code: (1) has well established and validated rules, (2) has a team of experts continually improving and updating it, (3) has software that can be used by designers, (4) extensive validation in many parts with available data from BE resources as well as input from Imperial college's database, and (5) was specifically developed for use in nuclear plants. R5 was specifically developed for use in gas cooled nuclear reactors which operate in the UK and much of the experience is based on materials and temperatures which are experienced in these reactors. If the next generation advanced reactors to be built in the US used these same materials within the same temperature ranges as these reactors, then R5 may be appropriate for consideration of direct implementation within ASME code NH or Section XI. However, until more verification and validation of these creep/fatigue crack growth rules for the specific materials and temperatures to be used in the GEN IV reactors is complete, ASME should consider delaying this implementation. With this in mind, it is this authors opinion that R5 methods are the best available for code use today. The focus of this work was to examine the literature for creep and creep-fatigue crack growth procedures that are well established in codes in other countries and choose a procedure to consider implementation into ASME NH. It is very important to recognize that all creep and creep fatigue crack growth procedures that are part of high temperature

  18. Hierarchical Petascale Simulation Framework for Stress Corrosion Cracking

    SciTech Connect (OSTI)

    Vashishta, Priya

    2014-12-01T23:59:59.000Z

    Reaction Dynamics in Energetic Materials: Detonation is a prototype of mechanochemistry, in which mechanically and thermally induced chemical reactions far from equilibrium exhibit vastly different behaviors. It is also one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. The CACS group has performed multimillion-atom reactive MD simulations to reveal a novel two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine (RDX) crystal. Rapid production of N2 and H2O within ~10 ps is followed by delayed production of CO molecules within ~ 1 ns. They found that further decomposition towards the final products is inhibited by the formation of large metastable C- and O-rich clusters with fractal geometry. The CACS group has also simulated the oxidation dynamics of close-packed aggregates of aluminum nanoparticles passivated by oxide shells. Their simulation results suggest an unexpectedly active role of the oxide shell as a nanoreactor.

  19. Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking

    SciTech Connect (OSTI)

    Das, S.K.; Ningileri, S.; Long, Z.; Saito, K.; Khraisheh, M.; Hassan, M.H.; Kuwana, K.; Han, Q.; Viswanathan, S.; Sabau, A.S.; Clark, J.; Hyrn, J. (ANL)

    2006-08-15T23:59:59.000Z

    Approximately 68% of the aluminum produced in the United States is first cast into ingots prior to further processing into sheet, plate, extrusions, or foil. The direct chill (DC) semi-continuous casting process has been the mainstay of the aluminum industry for the production of ingots due largely to its robust nature and relative simplicity. Though the basic process of DC casting is in principle straightforward, the interaction of process parameters with heat extraction, microstructural evolution, and development of solidification stresses is too complex to analyze by intuition or practical experience. One issue in DC casting is the formation of stress cracks [1-15]. In particular, the move toward larger ingot cross-sections, the use of higher casting speeds, and an ever-increasing array of mold technologies have increased industry efficiencies but have made it more difficult to predict the occurrence of stress crack defects. The Aluminum Industry Technology Roadmap [16] has recognized the challenges inherent in the DC casting process and the control of stress cracks and selected the development of 'fundamental information on solidification of alloys to predict microstructure, surface properties, and stresses and strains' as a high-priority research need, and the 'lack of understanding of mechanisms of cracking as a function of alloy' and 'insufficient understanding of the aluminum solidification process', which is 'difficult to model', as technology barriers in aluminum casting processes. The goal of this Aluminum Industry of the Future (IOF) project was to assist the aluminum industry in reducing the incidence of stress cracks from the current level of 5% to 2%. Decreasing stress crack incidence is important for improving product quality and consistency as well as for saving resources and energy, since considerable amounts of cast metal could be saved by eliminating ingot cracking, by reducing the scalping thickness of the ingot before rolling, and by eliminating butt sawing. Full-scale industrial implementation of the results of the proposed research would lead to energy savings in excess of 6 trillion Btu by the year 2020. The research undertaken in this project aimed to achieve this objective by a collaboration of industry, university, and national laboratory personnel through Secat, Inc., a consortium of aluminum companies. During the four-year project, the industrial partners and the research team met in 16 quarterly meetings to discuss research results and research direction. The industrial partners provided guidance, facilities, and experience to the research team. The research team went to two industrial plants to measure temperature distributions in commercial 60,000-lb DC casting ingot production. The project focused on the development of a fundamental understanding of ingot cracking and detailed models of thermal conditions, solidification, microstructural evolution, and stress development during the initial transient in DC castings of the aluminum alloys 3004 and 5182. The microstructure of the DC casting ingots was systematically characterized. Carefully designed experiments were carried out at the national laboratory and university facilities as well as at the industrial locations using the industrial production facilities. The advanced computational capabilities of the national laboratories were used for thermodynamic and kinetic simulations of phase transformation, heat transfer and fluid flow, solidification, and stress-strain evolution during DC casting. The achievements of the project are the following: (1) Identified the nature of crack formation during DC casting; (2) Developed a novel method for determining the mechanical properties of an alloy at the nonequilibrium mushy zone of the alloy; (3) Measured heat transfer coefficients (HTCs) between the solidifying ingot and the cooling water jet; (4) Determined the material constitutive model at high temperatures; and (5) Developed computational capabilities for the simulation of cracking formation in DC casting ingot. The models and the database de

  20. Method and apparatus for generating a natural crack

    DOE Patents [OSTI]

    Fulton, F.J.; Honodel, C.A.; Holman, W.R.; Weingart, R.C.

    1982-05-06T23:59:59.000Z

    A method and apparatus for generating a measurable natural crack includes forming a primary notch in the surface of a solid material. A nonsustained single pressure pulse is then generated in the vicinity of the primary notch, reuslting in the formation of a shock wave which travels through the material. The shock wave creates a measurable natural crack within the material which extends from the primary notch. The natural crack formed possesses predictable geometry, location and orientation.

  1. CYCLIC PLASTICITY OF A CRACKED STRUCTURE SUBJECTED TO MIXED MODE LOADING

    E-Print Network [OSTI]

    CYCLIC PLASTICITY OF A CRACKED STRUCTURE SUBJECTED TO MIXED MODE LOADING Sylvie Pommier1, a 1 LMT, mixed mode crack propagation, plasticity, crack deflection. Abstract. Cyclic plasticity in the crack tip stresses in the overload's plastic zone. Moreover, if the overload's ratio is large enough, the crack may

  2. LOW-FREQUENCY PHASED-ARRAY METHODS FOR CRACK DETECTION IN CAST AUSTENITIC PIPING COMPONENTS

    SciTech Connect (OSTI)

    Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.; Doctor, Steven R.

    2008-01-01T23:59:59.000Z

    Studies at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, are being conducted to evaluate nondestructive examination (NDE) approaches for inspecting coarse-grained, austenitic stainless steel reactor components. The work provides information to the United States Nuclear Regulatory Commission (NRC) on the utility, effectiveness, limitations, and reliability of advanced inspection techniques for application on safety-related components in commercial nuclear power plants. This paper describes results from recent assessments using a low-frequency phased-array methodology for detecting cracks in cast austenitic piping welds. Piping specimens that contain thermal and mechanical fatigue cracks located adjacent to welds were examined. The specimens have surface geometrical conditions and weld features that simulate portions of primary piping systems in many U.S. pressurized water reactors (PWRs). In addition, segments of vintage centrifugally cast piping were examined to assess inherent acoustic noise and scattering due to grain structures and determine consistency of ultrasonic (UT) responses from varied circumferential locations. The phased-array UT methods were applied from the outside surface of the specimens using automated scanning devices and water coupling, and employed a modified instrument operating between 500 kHz and 1.0 MHz. Composite volumetric images of the specimens were generated. Results from laboratory studies for assessing crack detection and sizing effectiveness are discussed, including acoustic parameters observed in centrifugally cast piping base materials.

  3. P wave anisotropy, stress, and crack distribution at Coso geothermal...

    Open Energy Info (EERE)

    Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: P wave anisotropy, stress, and crack distribution at Coso geothermal field, California...

  4. High-Resolution Crack Imaging Reveals Degradation Processes in...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Reveals Degradation Processes in Nuclear Reactor Structural Materials. Abstract: Corrosion and cracking represent critical failure mechanisms for structural materials in many...

  5. Physics-Based Stress Corrosion Cracking Component Reliability

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework Draft Report Supporting Technology Inputs to the Risk-...

  6. White-Etching Crack Failure Overview, Tomography Analysis, and...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    White-Etching Crack Failure Overview, Tomography Analysis, and Test Development Presented by Aaron Greco of Argonne National Laboratory at the Wind Turbine Tribology Seminar 2014....

  7. Investigation of White Etching Crack (WEC) Formation Mechanisms...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Investigation of White Etching Crack (WEC) Formation Mechanisms Under Non-hydrogen Charged Test Conditions Presented by Alex Richardson, Afton Chemical (representing University of...

  8. Tribological Analysis of White Etching Crack (WEC) Failures in...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Crack (WEC) Failures in Rolling Element Bearings Presented by Arnaud Ruellan, INSA de Lyon at the Wind Turbine Tribology Seminar 2014. 20141030NREL2014ArgonneRuellancomV...

  9. Cracking in reinforced concrete bent caps

    E-Print Network [OSTI]

    Young, Bradley S.

    2000-01-01T23:59:59.000Z

    ) . . . . . . . . . . . . . . . . 4. 2 Group It2 Response (Specimens 3C, 3D, 4C, 4E, 5D, 5E) . . . 4. 3 Group tt3 Response (Specimens 6F, 6G, 7F, 7H, 8G, 8H) . . . 4. 4 General Response 4. 5 Sununary. . . . . 49 . . . . 58 . . . . 64 70 . . . 75 5. STRUT-AND-TIE MODELING... be expressed as the product of the steel strain (s, ) at that level multiplied by the crack spacing (s, ); 20 w =z*s C S C (2. 6) a linear strain gradient can be used to project the maximum strain occurring at the level of the flexural reinforcement...

  10. 3:2:1 Crack Spread

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) " ,"Click worksheet9,1,50022,3,,,,6,1,,781Title: Telephone:short version)ecTotal (Data from:2:1 Crack Spread

  11. Crack opening area estimates in pressurized through-wall cracked elbows under bending

    SciTech Connect (OSTI)

    Franco, C.; Gilles, P.; Pignol, M.

    1997-04-01T23:59:59.000Z

    One of the most important aspects in the leak-before-break approach is the estimation of the crack opening area corresponding to potential through-wall cracks at critical locations during plant operation. In order to provide a reasonable lower bound to the leak area under such loading conditions, numerous experimental and numerical programs have been developed in USA, U.K. and FRG and widely discussed in literature. This paper aims to extend these investigations on a class of pipe elbows characteristic of PWR main coolant piping. The paper is divided in three main parts. First, a new simplified estimation scheme for leakage area is described, based on the reference stress method. This approach mainly developed in U.K. and more recently in France provides a convenient way to account for the non-linear behavior of the material. Second, the method is carried out for circumferential through-wall cracks located in PWR elbows subjected to internal pressure. Finite element crack area results are presented and comparisons are made with our predictions. Finally, in the third part, the discussion is extended to elbows under combined pressure and in plane bending moment.

  12. Controlling the Delay of Small Flows in Datacenters

    E-Print Network [OSTI]

    Carra, Damiano

    and CAPEX and ignore designs which could help reduce delay of delay sensitive flows. The flow routing

  13. Composite tube cracking in kraft recovery boilers: A state-of-the-art review

    SciTech Connect (OSTI)

    Singbeil, D.L.; Prescott, R. [Pulp and Paper Research Inst. of Canada, Vancouver, British Columbia (Canada); Keiser, J.R.; Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

    1997-07-01T23:59:59.000Z

    Beginning in the mid-1960s, increasing energy costs in Finland and Sweden made energy recovery more critical to the cost-effective operation of a kraft pulp mill. Boiler designers responded to this need by raising the steam operating pressure, but almost immediately the wall tubes in these new boilers began to corrode rapidly. Test panels installed in the walls of the most severely corroding boiler identified austenitic stainless steel as sufficiently resistant to the new corrosive conditions, and discussions with Sandvik AB, a Swedish tube manufacturer, led to the suggestion that coextruded tubes be used for water wall service in kraft recovery boilers. Replacement of carbon steel by coextruded tubes has solved most of the corrosion problems experienced by carbon steel wall tubes, however, these tubes have not been problem-free. Beginning in early 1995, a multidisciplinary research program funded by the US Department of Energy was established to investigate the cause of cracking in coextruded tubes and to develop improved materials for use in water walls and floors of kraft recovery boilers. One portion of that program, a state-of-the-art review of public- and private-domain documents related to coextruded tube cracking in kraft recovery boilers is reported here. Sources of information that were consulted for this review include the following: tube manufacturers, boiler manufacturers, public-domain literature, companies operating kraft recovery boilers, consultants and failure analysis laboratories, and failure analyses conducted specifically for this project. Much of the information contained in this report involves cracking problems experienced in recovery boiler floors and those aspects of spout and air-port-opening cracking not readily attributable to thermal fatigue. 61 refs.

  14. Development of reduced crude cracking catalysts

    SciTech Connect (OSTI)

    Hettinger, W.P. Jr. (Ashland Petroleum Company, KY (USA))

    1987-08-01T23:59:59.000Z

    In 1974 OPEC imposed an embargo on oil to the United States and caused a rapid rise in the price of a barrel of oil. At the time of the embargo, Ashland imported a considerable portion of its oil from the Middle East, thus raising the question of oil availability. As the problem increased in severity, Messrs. George Meyer, Oliver Zandona and Llyod Busch, began to explore alternative ways of squeezing more product from a given barrel of crude. After considering many alternatives, they arrived at the innovative thought that it might be possible to catalytically crack the 1050{degree}F plus fraction of the barrel directly to gasoline which would in effect, give them an additional volume of crude oil. Also, if vacuum fractionation were eliminated and if the entire 650{degree}F plus (reduced crude) portion of the barrel processed, this would further reduce operating costs. With these objectives and some new process innovations in mind, they began reduced crude cracking experimentation in a small 12,000 B/D FCC operating unit at Louisville. It was from these goals, concepts and a small operating unit, that the RCC process was born.

  15. E-Print Network 3.0 - applications crack growth Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    that the critical crack-tip opening angle (CTOA) value measured on the specimen... fracture changes a Mode-I type of crack growth to a mixed-mode IIII type of crack growth. It...

  16. The Influence of Crystallographic Orientation on Crack Tip Displacements of

    E-Print Network [OSTI]

    Cizelj, Leon

    consists of 212 randomly shaped, sized and oriented grains, loaded monotonically in uniaxial tension to a maximum load of 0.9Rp0.2 (240 MPa). The influence that a random grain structure imposes on a Stage I crack will preferably follow the slip plane where the crack tip opening displacement is highest, we show

  17. Fracture mechanics analysis of slow crack growth in polyethylene

    E-Print Network [OSTI]

    Self, Robert Alan

    1997-01-01T23:59:59.000Z

    Slow crack growth in polyethylene is often the limiting factor in long-term service of plastic pipe or other structural applications. A new test method and analysis method was developed to study slow crack growth in polyethylene. Two high density...

  18. NORTHWESTERN UNIVERSITY Crack Response to Weather Effects, Blasting, and Construction

    E-Print Network [OSTI]

    NORTHWESTERN UNIVERSITY Crack Response to Weather Effects, Blasting, and Construction Vibrations Acknowledgements iii Abstract iv List of Figures v List of Tables xi Chapter 1- Introduction 1 Chapter 2- Blast Vibration Response, Southbury, Connecticut 5 Structural Description Instrumentation Blast Response Crack

  19. Crack-based analysis of concrete with brittle reinforcement

    E-Print Network [OSTI]

    Burgoyne, Chris

    { FaberMaunsell Ltd; University of Cambridge Brittle reinforcement (such as fibre-reinforced plastic to the surround- ing concrete, at a crack surface sL=sR s on the left/right side of a crack u increase in unbonded

  20. Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models

    SciTech Connect (OSTI)

    Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L.

    1995-02-22T23:59:59.000Z

    The Ford/Andresen slip dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material condition. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

  1. SciTech Connect: Stress corrosion cracking of alloy 600 using...

    Office of Scientific and Technical Information (OSTI)

    Stress corrosion cracking of alloy 600 using the constant strain rate test Citation Details In-Document Search Title: Stress corrosion cracking of alloy 600 using the constant...

  2. E-Print Network 3.0 - assisted cracking resistance Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    crack... and the time-dependent, environmentally-assisted, crack initiation and subcritical growth in the oxide layer... of exploring these prin- ciples is seen in Figure 5....

  3. E-Print Network 3.0 - automated crack inspection Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    through micro cracks in the composite material... system with micro cracking induced damage is carried out. The effective permeability due ... Source: Popov, Peter - Institute of...

  4. Delays, Unstable Particles, and Transport Theory

    E-Print Network [OSTI]

    P. Danielewicz; S. Pratt

    1997-02-18T23:59:59.000Z

    Delays associated with elementary interaction processes are investigated. The case of broad resonances is discussed in the context of reaction simulations.

  5. On the combination of delayed neutron and delayed gamma techniques for fission rate measurement in nuclear fuel

    SciTech Connect (OSTI)

    Perret, G.; Jordan, K. A. [Paul Scherrer Institut, Villigen, 5232 (Switzerland)

    2011-07-01T23:59:59.000Z

    Novel techniques to measure newly induced fissions in spent fuel after re-irradiation at low power have been developed and tested at the Proteus zero-power research reactor. The two techniques are based on the detection of high energy gamma-rays emitted by short-lived fission products and delayed neutrons. The two techniques relate the measured signals to the total fission rate, the isotopic composition of the fuel, and nuclear data. They can be combined to derive better estimates on each of these parameters. This has potential for improvement in many areas. Spent fuel characterisation and safeguard applications can benefit from these techniques for non-destructive assay of plutonium content. Another application of choice is the reduction of uncertainties on nuclear data. As a first application of the combination of the delayed neutron and gamma measurement techniques, this paper shows how to reduce the uncertainties on the relative abundances of the longest delayed neutron group for thermal fissions in {sup 235}U, {sup 239}Pu and fast fissions in {sup 238}U. The proposed experiments are easily achievable in zero-power research reactors using fresh UO{sub 2} and MOX fuel and do not require fast extraction systems. The relative uncertainties (1{sigma}) on the relative abundances are expected to be reduced from 13% to 4%, 16% to 5%, and 38% to 12% for {sup 235}U, {sup 238}U and {sup 239}Pu, respectively. (authors)

  6. Influence of uniaxial pressure on the critical temperature for long delays in GaAs junction lasers

    SciTech Connect (OSTI)

    Morosini, M.B.Z.; Patel, N.B.; Nunes, F.D.

    1980-09-01T23:59:59.000Z

    In this work we report on the influence of uniaxial pressure applied perpendicularly to junction laser on the behavior of the critical temperature for the onset of long delays in GaAs junction lasers. Experimental data showing this influence for lasers operating in a TE or TM polarization are presented and explained on the basis of a thermal theory of long delays and related phenomena.

  7. Insights into Stress Corrosion Cracking Mechanisms from High-Resolution Measurements of Crack-Tip Structures and Compositions

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Thomas, Larry E.

    2010-04-05T23:59:59.000Z

    The fundamental basis for mechanistic understanding and modeling of SCC remains in question for many systems. Specific mechanisms controlling SCC can vary with changes in alloy characteristics, applied/residual stress or environmental conditions. The local crack electrochemistry, crack-tip mechanics and material metallurgy are the main factors controlling crack growth. These localized properties are difficult or impossible to measure in active cracks. Nevertheless, it is essential to quantitatively interrogate these crack-tip conditions if mechanistic understanding is to be obtained. A major recent advance has been the ability to investigate SCC cracks and crack tips using high-resolution ATEM techniques. ATEM enables the characterization of SCC cracks including trapped tip solution chemistries, corrosion product/film compositions and structures, and elemental composition gradients and defect microstructures along the crack walls and at the crack tip. A wide variety of methods for imaging and analyses at resolutions down to the atomic level can be used to examine the crack and corrosion film characteristics. Surface films and reaction layers have been examined by cross-sectional TEM techniques, but little work had been conducted on environmentally induced internal cracks until that of Lewis and co-workers [1-3] and the current authors [4-17]. This capability combined with modern ATEM techniques has enabled exciting new insights into corrosion processes occurring at buried interfaces and is being used to identify mechanisms controlling IGSCC in boiling water reactor (BWR) and pressurized water reactor (PWR) components. The objective of this paper is to summarize certain results focused on IGSCC of Fe- base and Ni-base stainless alloys in high-temperature water environments. Representative crack-tip examples will be shown to illustrate specific aspects that are characteristic of SCC in the material/environment combinations. Differences and similarities in crack-tip structures- chemistries will be highlighted comparing Fe-base 316/304SS to Ni-base alloy 600/182 and for tests in oxidizing versus hydrogenated water environments.

  8. Design of a novel conduction heating based stress-thermal cycling apparatus for composite materials and its utilization to characterize composite microcrack damage thresholds

    E-Print Network [OSTI]

    Ju, Jaehyung

    2006-10-30T23:59:59.000Z

    performed as a function of mechanical inplane strain levels, heating rates, and number of thermal cycles. The apparatus generated cracks related to the in-plane stresses (or strains) on plies. The design and analysis concept of the synergistic stress...

  9. Saber's heavy oil cracking refinery project

    SciTech Connect (OSTI)

    Benefield, C.S.; Glasscock, W.L.

    1983-03-01T23:59:59.000Z

    Perhaps more than any other industry, petroleum refining has been subjected to the radical swings in business and political climates of the past several decades. Because of the huge investments and long lead times to construct refining facilities, stable government policies, predictable petroleum prices, secure feedstock supplies and markets, and reliable cost estimates are necessary ingredients to effectively plan new refinery projects. However, over the past ten years the political and economic climates have provided anything but these conditions. Yet, refiners have demonstrated a willingness to undertake risks by continuing to expand and modernize their refineries. The refining business -- just as most businesses -- responds to economic incentives. These incentives, when present, result in new technology and capacity additions. In the 1940's, significant technology advances were commercialized to refine higher-octane motor gasolines. Such processes as continuous catalytic cracking (Houdry Process Corporation), fluid catalytic cracking (Standard Oil Development Company), HF alkylation (UOP and Phillips Petroleum Company), and catalytic reforming (UOP) began to supply a growing gasoline market, generated from the war effort and the ever increasing numbers of automobiles on the road. The post-war economy of the 1950's and 1960's further escalated demand for refined products, products which had to meet higher performance specifications and be produced from a wider range of raw materials. The refining industry met the challenge by introducing hydro-processing technology, such as hydrocracking developed in 1960. But, the era must be characterized by the large crude processing capacity additions, required to meet demand from the rapidly expanding U.S. economy. In 1950, refining capacity was 6.2 million BPD. By 1970, capacity had grown to 11.9 million BPD, an increase of 91%.

  10. Implications of early stages in the growth of stress corrosion cracking on component reliability

    SciTech Connect (OSTI)

    Jones, R.H.; Simonen, E.P.

    1995-04-01T23:59:59.000Z

    Environment-induced crack growth generally progresses through several stages prior to component failure. Crack initiation, short crack growth, and stage 1 growth are early stages in crack development that are summarized in this paper. The implications of these stages on component reliability, derive from the extended time that the crack exists in the early stages because crack velocity is slow. The duration of the early stages provides a greater opportunity for corrective action if cracks can be detected. Several important factors about the value of understanding short crack behavior include: (1) life prediction requires a knowledge of the total life cycle of the crack including the early stages, (2) greater reliability is possible if the transition between short and long crack behavior is known component life after this transition is short and (3) remedial actions are more effective for short than long cracks.

  11. Cracking blends of gas oil and residual oil

    SciTech Connect (OSTI)

    Myers, G.D.

    1988-03-01T23:59:59.000Z

    In a catalytic cracking process unit wherein a gas oil feed is cracked in a cracking zone at an elevated temperature in the presence of a cracking catalyst, the cracking catalyst is regenerated in a regeneration zone by burning coke of the catalyst, and catalyst is circulated between the cracking zone and the regeneration zone. The improvement is described for obtaining a naphtha product of improved octane number comprising introducing sufficient of a nickel and vanadium metals-containing heavy feedstock with the gas oil feed introduced into the cracking zone to deposit nickel and vanadium metals on the catalyst and raise the nickel and metals-content of the catalyst to a level ranging from about 1500 to about 6000 parts per million of the metals expressed as equivalent nickel, based on the weight of the catalyst, and maintaining the nickel and vanadium metals level on the catalyst by withdrawing high nickel and vanadium metals containing catalyst and adding low nickel and vanadium metals-containing catalyst to the regeneration zone.

  12. Benchmark Results for Delayed Neutron Data

    SciTech Connect (OSTI)

    Marck, S.C. van der; Meulekamp, R. Klein; Hogenbirk, A.; Koning, A.J. [Nuclear Research and Consultancy Group NRG, P.O. Box 25, NL-1755 ZG Petten (Netherlands)

    2005-05-24T23:59:59.000Z

    We have calculated the effective delayed neutron fraction {beta}eff for 32 benchmark configurations for which measurements have been reported. We use these results to test the delayed neutron data of JEFF-3.0, ENDF/B-VI.8, and JENDL-3.3.

  13. The Tunnel Vision Syndrome: Massively Delaying Progress

    E-Print Network [OSTI]

    Hartenstein, Reiner

    The Tunnel Vision Syndrome: Massively Delaying Progress Reiner Hartenstein, Professor, IEEE fellow facet as the complete answer are far from solving the problem. What is the reason of these slow-down- stream-based computing was delayed for decades by the tunnel vision syndrome. The History of Systolic

  14. FPGA Interconnect Delay Fault Testing Erik Chmelar

    E-Print Network [OSTI]

    Stanford University

    A satisfactory FPGA testing method meets several crite- ria. First, the routing resources must be explicitlyFPGA Interconnect Delay Fault Testing Erik Chmelar Center for Reliable Computing Stanford is a scalable manufactur- ing test method for all SRAM-based FPGAs, able to detect multiple interconnect delay

  15. Beta-Delayed Two-Particle Emission

    SciTech Connect (OSTI)

    Borge, M.J.G.

    2000-12-31T23:59:59.000Z

    A panorama of beta-delayed nuclear decay is sketched. Beginning with beta-delayed two-neutron emission, the author moves on to beta-delayed two-proton emission and beta-delayed multiparticle emission. After touching briefly on the theoretical approach to understanding these phenomena, he reports on two experiments done at ISOLDE (CERN) on the decay of {sup 31}Ar with the goal of studying the mechanisms of {beta}-delayed two proton emission. This example shows the potentiality of the new technology that allows design setups with high efficiency for multiparticle detection. In combination with high-purity sources and the use of low-energy beams to produce point-like sources, information at the drip line can be extracted that is of comparable quality to that obtained near stability.

  16. Possible Fine Structure in the Delayed Neutron Yields in the Resonance Region for Pu-239

    SciTech Connect (OSTI)

    Ohsawa, Takaaki; Torii, Takayuki [Department of Electrical and Electronic Engineering, Kinki University, Higashi-osaka 577-8502 (Japan); Hambsch, Franz-Josef [EC-JRC-Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium)

    2005-05-24T23:59:59.000Z

    A method of analysis of fluctuation in the delayed neutron yield on the basis of the multimodal fission model was applied to the low-energy resolved resonances for Pu-239. The present calculation using recent data of the fluctuation of the mode branching ratios for the resolved resonances showed both positive and negative resonance structure in the delayed neutron yield relative to the thermal neutron value. This is in contrast to the U-235 case, for which mainly negative dips of about -3.5% were predicted.

  17. Thermal neutron imaging support with other laboratories BL06-IM-TNI

    SciTech Connect (OSTI)

    Vanier,P.E.

    2008-06-17T23:59:59.000Z

    The goals of this project are: (1) detect and locate a source of thermal neutrons; (2) distinguish a localized source from uniform background; (3) show shape and size of thermalizing material; (4) test thermal neutron imager in active interrogation environment; and (5) distinguish delayed neutrons from prompt neutrons.

  18. A three-dimensional validation of crack curvature in muscovite mica

    SciTech Connect (OSTI)

    J. C. Hill; J. W. Foulk III; P. A. Klein; E. P. Chen

    2001-01-07T23:59:59.000Z

    Experimental and computational efforts focused on characterizing crack tip curvature in muscovite mica. Wedge-driven cracks were propagated under monochromatic light. Micrographs verified the subtle curvature of the crack front near the free surface. A cohesive approach was employed to model mixed-mode fracture in a three-dimensional framework. Finite element calculations captured the crack curvature observed in experiment.

  19. Author's personal copy Effect of fluid salinity on subcritical crack propagation in calcite

    E-Print Network [OSTI]

    Author's personal copy Effect of fluid salinity on subcritical crack propagation in calcite Fatma Accepted 22 October 2012 Available online 31 October 2012 Keywords: Subcritical crack growth Calcite Salt Damage The slow propagation of cracks, also called subcritical crack growth, is a mechanism of fracturing

  20. Automated crack control analysis for concrete pavement construction

    E-Print Network [OSTI]

    Jang, Se Hoon

    2005-11-01T23:59:59.000Z

    The focus of this research is on the control of random cracking in concrete paving by using sawcut notch locations in the early stages of construction. This is a major concern in concrete pavement construction. This research also addresses a...

  1. Field Examples of Axial Cracked Bearings in Wind Turbine Gearboxes...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Field Examples of Axial Cracked Bearings in Wind Turbine Gearboxes Presented by Paul John Baker of FrontierPro Services at the Wind Turbine Tribology Seminar 2014. 141030 Axial...

  2. Modeling of crack initiation, propagation and coalescence in rocks

    E-Print Network [OSTI]

    Gonçalves da Silva, Bruno Miguel

    2009-01-01T23:59:59.000Z

    Natural or artificial fracturing of rock plays a very important role in geologic processes and for engineered structures in and on rock. Fracturing is associated with crack initiation, propagation and coalescence, which ...

  3. PLASMA Approximate Dynamic Programming finally cracks the locomotive optimization problem

    E-Print Network [OSTI]

    Powell, Warren B.

    PLASMA ­ Approximate Dynamic Programming finally cracks the locomotive optimization problem schedules and new operating policies. PLASMA is currently running at Norfolk Southern for strategic of PLASMA: Each locomotive is modeled individually, making it possible to capture both horsepower

  4. J-integral values for cracks in conventional fatigue specimens

    SciTech Connect (OSTI)

    O`Donnell, T.P.; O`Donnell, W.J. [O`Donnell Consulting Engineers, Pittsburgh, PA (United States)

    1996-12-01T23:59:59.000Z

    Comprehensive S-N fatigue data has been developed worldwide using conventional low-cycle fatigue tests. Such tests use smooth unnotched specimens subjected to controlled axial deflection or strain ranges. The tests must be run in the plastic regime in order to achieve the required cycles-to-failure. Recent developments have highlighted the need to understand and interpret the significance of the resulting strain range vs. cycles to failure data in terms of crack initiation and propagation. Since conventional fatigue tests are conducted in the plastic regime, linear elastic fracture mechanics cannot be used to accurately quantify crack growth in such tests. Elastic-plastic J-integral theory, however, has been shown to provide excellent correlations of crack growth in the elastic, elastic-plastic and grossly-plastic regimes for a wide range of geometric and loading conditions. The authors are applying this theory to the low-cycle fatigue specimen crack behavior. As cracks progress in conventional fatigue specimens, bending becomes significant. Since fatigue testing machines are quite stiff relative to the small fatigue specimens, the ends of the specimen are constrained to remain parallel, and this reduces bending in the cracked cross-section. Three-dimensional finite element elastic-plastic analyses are required to include these constraints in the J-integral solutions.

  5. Assessment of crack opening area for leak rates

    SciTech Connect (OSTI)

    Sharples, J.K.; Bouchard, P.J.

    1997-04-01T23:59:59.000Z

    This paper outlines the background to recommended crack opening area solutions given in a proposed revision to leak before break guidance for the R6 procedure. Comparisons with experimental and analytical results are given for some selected cases of circumferential cracks in cylinders. It is shown that elastic models can provide satisfactory estimations of crack opening displacement (and area) but they become increasingly conservative for values of L{sub r} greater than approximately 0.4. The Dugdale small scale yielding model gives conservative estimates of crack opening displacement with increasing enhancement for L{sub r} values greater than 0.4. Further validation of the elastic-plastic reference stress method for up to L{sub r} values of about 1.0 is presented by experimental and analytical comparisons. Although a more detailed method, its application gives a best estimate of crack opening displacement which may be substantially greater than small scale plasticity models. It is also shown that the local boundary conditions in pipework need to be carefully considered when evaluating crack opening area for through-wall bending stresses resulting from welding residual stresses or geometry discontinuities.

  6. ffe1098 FFE March 7, 2007 21:55 Crack tip displacements of microstructurally small cracks in 316L steel

    E-Print Network [OSTI]

    Cizelj, Leon

    steel and their dependence on crystallographic orientations of grains I. SIMONOVSKI1 , KARL orientations on a short Stage I surface crack in a 316L stainless steel. The analysis is based on a plane

  7. Strengthening, Crack Arrest And Multiple Cracking In Brittle Materials Using Residual Stresses.

    DOE Patents [OSTI]

    Green, David J. (State College, PA); Sglavo, Vincenzo M. (Roncegno, IT); Tandon, Rajan (Fremont, CA)

    2003-02-11T23:59:59.000Z

    Embodiments include a method for forming a glass which displays visible cracking prior to failure when subjected to predetermined stress level that is greater than a predetermined minimum stress level and less than a failure stress level. The method includes determining a critical flaw size in the glass and introducing a residual stress profile to the glass so that a plurality of visible cracks are formed prior to failure when the glass is subjected to a stress that is greater than the minimum stress level and lower than the critical stress. One method for forming the residual stress profile includes performing a first ion exchange so that a first plurality of ions of a first element in the glass are exchanged with a second plurality of ions of a second element that have a larger volume than the first ions. A second ion exchange is also performed so that a plurality of the second ions in the glass are exchanged back to ions of the first element.

  8. Matrix fatigue cracking mechanisms of alpha(2) TMC for hypersonic applications

    SciTech Connect (OSTI)

    Gabb, T.P.; Gayda, J.

    1994-02-01T23:59:59.000Z

    The objective of this work was to understand matrix cracking mechanisms in a unidirectional alpha[sub 2] TMC in possible hypersonic applications. A (0)[sub 8] SCS-6/Ti-24Al-11Nb (at. percent) TMC was first subjected to a variety of simple isothermal and nonisothermal fatigue cycles to evaluate the damage mechanisms in simple conditions. A modified ascent mission cycle test was then performed to evaluate the combined effects of loading modes. This cycle mixes mechanical cycling at 150 and 483 C, sustained loads, and a slow thermal cycle to 815 C. At low cyclic stresses and strains more common in hypersonic applications, environment-assisted surface cracking limited fatigue resistance. This damage mechanism was most acute for out-of-phase nonisothermal cycles having extended cycle periods and the ascent mission cycle. A simple linear fraction damage model was employed to help understand this damage mechanism. Time-dependent environmental damage was found to strongly influence out-of-phase and mission life, with mechanical cycling damage due to the combination of external loading and CTE mismatch stresses playing a smaller role. The mechanical cycling and sustained loads in the mission cycle also had a smaller role.

  9. Matrix fatigue cracking in {alpha}{sub 2} titanium matrix composites for hypersonic applications

    SciTech Connect (OSTI)

    Gabb, T.P.; Gayda, J. [NASA Lewis Research Center, Cleveland, OH (United States)

    1996-12-31T23:59:59.000Z

    The objective of this work was to understand matrix cracking mechanisms in a unidirectional {alpha}{sub 2} titanium matrix composite (TMC) in possible hypersonic applications. A [0]{sub 8} SCS-6/Ti-24Al-11Nb (atomic %) TMC was first subjected to a variety of simple isothermal and nonisothermal fatigue cycles to evaluate the damage mechanisms in simple conditions. A modified ascent mission cycle test was then performed to evaluate the combined effects of loading modes. This cycle mixes mechanical cycling at 150 and 483 C, sustained loads, and a slow thermal cycle to 815 C. At low cyclic stresses and strains more common in hypersonic applications, environment-assisted surface cracking limited fatigue resistance. This damage mechanism was most acute for out-of-phase nonisothermal cycles having extended cycle periods and the ascent mission cycle. A simple linear fraction damage model was employed to help understand this damage mechanism. Time-dependent environmental damage was found to strongly influence out-of-phase and mission life, with mechanical cycling damage due to the combination of external loading and CTE mismatch stresses playing a smaller role. The mechanical cycling and sustained loads in the mission cycle also had a smaller role.

  10. Crack growth rates and fracture toughness of irradiated austenitic stainless steels in BWR environments.

    SciTech Connect (OSTI)

    Chopra, O. K.; Shack, W. J.

    2008-01-21T23:59:59.000Z

    In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and stress corrosion cracking conditions were determined. A superposition model was used to represent the cyclic CGRs of austenitic SSs. The effects of neutron irradiation on the fracture toughness of these steels, as well as the effects of material and irradiation conditions and test temperature, have been evaluated. A fracture toughness trend curve that bounds the existing data has been defined. The synergistic effects of thermal and radiation embrittlement of cast austenitic SS internal components have also been evaluated.

  11. Multiple use of waste catalysts with and without regeneration for waste polymer cracking

    SciTech Connect (OSTI)

    Salmiaton, A., E-mail: mie@eng.upm.edu.my [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia (UPM), 43400 UPM Serdang, Selangor (Malaysia); Garforth, A.A. [School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Sackville Street, Manchester M60 1QD (United Kingdom)

    2011-06-15T23:59:59.000Z

    Waste plastics contain a substantial number of valuable chemicals. The wastes from post-consumer as well as from industrial production can be recycled to valuable chemical feedstock, which can be used in refineries and/or petrochemical industries. This chemical recycling process is an ideal approach in recycling the waste for a better environment. Polymer cracking using a laboratory fluidised bed reactor concentrated on the used highly contaminated catalyst, E-Cat 2. Even though E-Cat 2 had low activity due to fewer acid sites, the products yielded were similar with amorphous ASA and were far better than thermal cracking. The high levels of heavy metals, namely nickel and vanadium, deposited during their lifetime as an FCC catalyst, did not greatly affect on the catalyst activity. It was also shown that E-Cat 2 could be used with and without regeneration. Although there was more deactivation when there was no regeneration step, the yield of gases (C{sub 2}-C{sub 7}) remained fairly constant. For the first time, these results indicate that 'waste' FCC catalyst (E-Cat) is a good candidate for future feedstock recycling of polymer waste. The major benefits of using E-Cat are a low market price, the ability to tolerate reuse and regeneration capacity.

  12. Construction project delay-analysis techniques

    E-Print Network [OSTI]

    Al-Humaidi, Hanouf M

    2012-06-07T23:59:59.000Z

    of this rcscarch bcncfit different parties among the construction industry such as the owners, dcsigncrs, contractors, and lawyers. DEDICATION For my parents, Haya and Mohammad, whose love and support have guided me throughout and carried me at times. Fo&r... OWNER PROJECT 3 AS-BUILT WITHOUT DELAY SCHEDULE APPENDIX D PUBLIC OWNER 3 SNAPSHOT SCHEDULE ON APRIL 21, 1997 . APPENDIX E PUBLIC OWNER 3 SNAPSHOT SCHEDULE ON MAY 10 ", 1997. APPENDIX F PUBLIC OWNER 3 DELAY-ANALYSIS USING ANALYSIS...

  13. Identification and use of surrogate precursors to represent delayed neutron groups

    SciTech Connect (OSTI)

    Loaiza, D.J. [Los Alamos National Lab., NM (United States); Haskin, F.E. [Univ. of New Mexico, Albuquerque, NM (United States)

    1998-09-01T23:59:59.000Z

    Time-dependent delayed neutron activities have traditionally been represented by six delayed neutron precursor groups, whose yields and decay constants are obtained from nonlinear least-squares fits to out-of-pile measurements. The group decay constants obtained in this manner are empirical. They do not coincide with decay constants of specific delayed neutron precursors. Different values are used for each fissionable nuclide, and the values used also depend on the energy spectrum of the neutrons causing fission. Having a different value of the six-group decay constants for each fissionable nuclide complicates the analysis of the dynamic behavior of fast reactors. A fast reactor containing six principal fissioning nuclides of uranium and plutonium must, in effect, be described by 36 delayed neutron groups. The use of group decay constants that depend on the neutron energy spectrum makes it difficult to select values that describe the dynamic response of epithermal systems because virtually all delayed neutron activity measurements have been performed for fast or thermal spectra. Clearly, it would be desirable to have a single set of group decay constants that could be applied to all fissionable nuclei. A set of seven fixed decay constants is associated with a specific, dominant delayed neutron precursor. In effect, each group is represented by a single surrogate precursor. Using recently measured delayed neutron activities for {sup 235}U and {sup 237}Np, the proposed set of decay constants actually improved the fit to the data. For other fissionable nuclei, a method has been devised to obtain yields consistent with the proposed set of decay constants from the traditional six-group parameters. This transformation is accomplished without altering the inferred reactivity scale.

  14. High-Resolution Characterizations of Stress-Corrosion Cracks in Austenitic Stainless Steel from Crack Growth Tests in BWR-Simulated Environments

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Thomas, Larry E.

    2005-07-20T23:59:59.000Z

    Mechanisms controlling environmental degradation and cracking in light-water-reactor (LWR) systems have been investigated by analytical transmission electron microscopy (ATEM) of cracks and crack tips. The current work focuses on intergranular stress corrosion cracking (IGSCC) of 300-series, austenitic stainless steels in high-temperature LWR environments. Comparisons are made between cold-worked 304SS containing stress-corrosion cracks produced in a simulated boiling-water-reactor (BWR) environment during crack-growth tests, and a 304SS core component with cracks produced during 26-year BWR service. Similar corrosion products consisting of duplex-layered spinel oxides were found along the walls of open cracks in the service and laboratory test samples. These oxide films consisted of oriented Cr-rich spinel up to ~30 nm thick along the metal crack walls and large-grained Fe-rich spinel at the crack centers. Cracks in the service sample were generally more filled with oxide, perhaps reflecting the much longer times available for corrosion to occur after the crack passage. Crack tips in the BWR top-guide sample exhibited unique and unexpected structures with oxide-filled cracks <10 nm wide ending in finger-like attack and locally “dealloyed” zones of Fe/Cr-depleted, Ni-rich metal. Alloy compositions measured at numerous crack tips were 40 wt% Fe, 4 wt% Cr and 55 wt% Ni immediately ahead of the degradation front versus approximately 70 wt% Fe, 19 wt% Cr and 9 wt% Ni in the bulk 304SS. Laboratory samples with cracks grown over much shorted times (~1.5 months) did not show the distinctive crack tip structures or strong Ni enrichment in the metal ahead of the crack tips as for the service sample. This suggests that although selective oxidation processes occur during degradation, significant composition differences may only develop after crack propagation has slowed or stopped. Additional nanometer-scale measurements elucidating corrosion processes occurring during crack advance are presented to provide insights into mechanisms controlling IGSCC.

  15. On the modeling of time-varying delays

    E-Print Network [OSTI]

    Shah, Chirag Laxmikant

    2004-09-30T23:59:59.000Z

    This thesis is an effort to develop generalized dynamic models for systems with time-varying time delays. Unlike the simple time-delay model characterized by a transportation lag in the case of a fixed time delay, time-varying delays exhibit quite...

  16. Influence of cracking on the diffusion properties of cement-based materials. Part I: Influence of continuous cracks on the steady-state regime

    SciTech Connect (OSTI)

    Gerard, B.; Marchand, J.

    2000-01-01T23:59:59.000Z

    The influence of traversing cracks on the steady-state diffusion properties of concrete was studied. The effect of both anisotropic and isotropic crack networks was first theoretically assessed using an analytical approach. To simplify the transport equations, cracks were assumed to be of uniform size and evenly distributed on a one- or two-dimensional grid. Results of the theoretical analysis were then compared to experimental data. Both series of results indicate that cracking can markedly alter the diffusion properties of the material and favor the penetration (or the leaching) of drifting species. A simple method to predict the effect of cracking on the concrete diffusivity is proposed. Predictions are made on the basis of two parameters: the crack density and the mean crack aperture. This method can provide a first estimate of the diffusion properties of severely damaged concrete elements.

  17. Delay correlation analysis and representation for vital complaint VHDL models

    DOE Patents [OSTI]

    Rich, Marvin J.; Misra, Ashutosh

    2004-11-09T23:59:59.000Z

    A method and system unbind a rise/fall tuple of a VHDL generic variable and create rise time and fall time generics of each generic variable that are independent of each other. Then, according to a predetermined correlation policy, the method and system collect delay values in a VHDL standard delay file, sort the delay values, remove duplicate delay values, group the delay values into correlation sets, and output an analysis file. The correlation policy may include collecting all generic variables in a VHDL standard delay file, selecting each generic variable, and performing reductions on the set of delay values associated with each selected generic variable.

  18. Stress-corrosion cracking in BWR and PWR piping

    SciTech Connect (OSTI)

    Weeks, R.W.

    1983-07-01T23:59:59.000Z

    Intergranular stress-corrosion cracking of weld-sensitized wrought stainless steel piping has been an increasingly ubiquitous and expensive problem in boiling-water reactors over the last decade. In recent months, numerous cracks have been found, even in large-diameter lines. A number of potential remedies have been developed. These are directed at providing more resistant materials, reducing weld-induced stresses, or improving the water chemistry. The potential remedies are discussed, along with the capabilities of ultrasonic testing to find and size the cracks and related safety issues. The problem has been much less severe to date in pressurized-water reactors, reflecting the use of different materials and much lower coolant oxygen levels.

  19. Hydrocarbon cracking with yttrium exchanged zeolite y catalyst

    SciTech Connect (OSTI)

    Lochow, C.F.; Kovacs, D.B.

    1987-05-12T23:59:59.000Z

    A process is described for cracking a gas oil boiling range hydrocarbon feedstock comprising the step of contacting the feedstock in a catalytic cracking zone under catalytic cracking conditions to produce convulsion products comprising gasoline with a catalyst composition. The process comprises: a Y crystalline aluminosilicate zeolite, having the structure of faujasite and having uniform pore diameters and a silica to alumina mole ratio of at least about 5; an inorganic oxide matrix; and the zeolite having been ion exchanged with a mixture of rare earths prior to compositing with the matrix; and the zeolite having been subsequently further ion exchanged with yttrium following compositing with the matrix, whereby the catalyst composition contains 0.30 to 3.0 wt% yttrium.

  20. Protocol development for evaluation of commercial catalytic cracking catalysts

    SciTech Connect (OSTI)

    Mitchell, M.M. Jr.; Moore, H.F. (Ashland Petroleum Co., KY (USA))

    1988-09-01T23:59:59.000Z

    A complete, new set of testing protocols has been developed for qualification of catalysts for Ashland's commercial catalytic cracking units. The objective of this test development is to identify new generations of improved cracking catalysts. Prior test protocols have classically utilized microactivity (MAT) testing of steamed virgin catalysts, while more advanced methods have utilized fixed fluid bed and/or circulating pilot units. Each of these techniques, however, have been limited by their correlation to commercial operations, weaknesses in metallation and preparation of pseudo-equilibrium catalysts, and mechanical constraints on the use of heavy, vacuum bottoms-containing feedstocks. These new protocols have been baselined, compared to commercial Ashland results on known catalytic cracking catalysts, and utilized to evaluate a range of potentially new catalyst samples.

  1. Method for fabrication of crack-free ceramic dielectric films

    DOE Patents [OSTI]

    Ma, Beihai; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan; Narayanan, Manoj

    2014-02-11T23:59:59.000Z

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprise the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. Also provided was a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  2. Determination of Godiva`s effective delayed neutron fraction using newly calculated delayed neutron spectra

    SciTech Connect (OSTI)

    Spriggs, G.D.; Campbell, J.M. [Los Alamos National Lab., NM (United States); Busch, R.D. [Univ. of New Mexico, Albuquerque, NM (United States)

    1999-09-01T23:59:59.000Z

    When calculating the effective delayed neutron fraction {beta}{sub eff} for a given reactor system, the assumed delayed neutron group spectra and the assumed number of delayed neutrons born per fission {nu}{sub d} can have a major impact on the final value. Over the years, the recommended values for the delayed neutron spectra and for {nu}{sub d} have slowly changed. To ascertain whether or not these changes have increased the accuracy of {beta}{sub eff} calculations in fast {sup 235}U systems, the authors have reevaluated {beta}{sub eff} for the benchmark system Godiva-I using newly calculated delayed neutron spectra and Tuttle`s recommended values of {nu}{sub d} for both {sup 235}U and {sup 238}U.

  3. Weld solidification cracking in 304 to 204L stainless steel

    SciTech Connect (OSTI)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-09-15T23:59:59.000Z

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  4. Weld solidification cracking in 304 to 304L stainless steel

    SciTech Connect (OSTI)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  5. Time-delayed quantum feedback control

    E-Print Network [OSTI]

    Arne L. Grimsmo

    2015-02-24T23:59:59.000Z

    A theory of time-delayed coherent quantum feedback is developed. More specifically, we consider a quantum system coupled to a bosonic reservoir creating a unidirectional feedback loop. It is shown that the dynamics can be mapped onto a fictitious quantum cascade, where the system is driven by past versions of itself. The derivation of this model relies on a tensor network representation of the system-reservoir time-propagator. For concreteness, this general theory is applied to a driven two-level atom scattering into a coherent feedback loop. We demonstrate how delay effects can qualitatively change the dynamics of the atom, and how quantum control can be implemented in the presence of time-delays. A realization with a superconducting qubit serving as an artificial atom is discussed.

  6. Reflective Cracking Study: First-level Report on HVS Testing on Section 588RF - 90 mm AR4000-DOverlay

    E-Print Network [OSTI]

    Jones, David; Wu, R; Harvey, John T

    2008-01-01T23:59:59.000Z

    testing being performed to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete.concrete. It describes the results of the fourth HVS reflective cracking testingconcrete. It describes the results of the fourth HVS reflective cracking testing

  7. Reflective Cracking Study: First-Level Report on HVS Testing on Section 590RF - 90 mm MB4-G Overlay

    E-Print Network [OSTI]

    Jones, David; Tsai, Bor-Wen; Harvey, John T

    2008-01-01T23:59:59.000Z

    testing being performed to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete.concrete. It describes the results of the first HVS reflective cracking testingconcrete. It describes the results of the first HVS reflective cracking testing

  8. Model of crack propagation in a clay soil

    E-Print Network [OSTI]

    Carriere, Patrick Edwidge

    2012-06-07T23:59:59.000Z

    of independent variables for maximum R to determine A for crack de th, 2 Number of variables in model (p) R Variables in model 0. 703913 0. 916176 0. 988151 0. 997207 0. 999328 H*CLrH*M~CL H, H*M, H~M*CL H, CL, H*M, H*M*CL H, CL, H"M, H*CL, H...: Agricultural Engineering MODEL OF CRACK PROPAGATION IN A CLAY SOIL A Thesis by PATRICK EDWIDGE CARRIERE Approved as to style and content by: John L. Nieber (Chairman of Committee) Donald L. Reddell (Member) Kirk W, Brown (Member ) Wilbert H...

  9. Stress relief cracking in creep resisting low alloy ferritic steels.

    E-Print Network [OSTI]

    Tait, Robert Andrew

    1976-10-26T23:59:59.000Z

    , for their inspiration by example, to Messrs. R.Turkentine, S. Charter, D. Evans, P.Hull and D.Duke, for their guidance and assistfu.ce during all stages of the experi- mental work; also to Professor G.S.Kent, Dr.M.N.Mct1orris, Professor T.P.Hughes, Dr... >eased and inter>granular> cavitation cracking increased. Indeed the mixed upper> and lower> bainite matr>ix pr>oduced by oil quenching, showed ver>y br>ittle behaviOUr> associated with little opening of the intergranular cr>acKs. The implication...

  10. Stress Corrosion Crack Detection on HU-25 Guardian Aircraft

    SciTech Connect (OSTI)

    Blackmon, R.; Huffman, J.; Mello, C.W.; Moore, D.G.; Walkington, P.D.

    1999-02-17T23:59:59.000Z

    Several ultrasonic inspection methods were developed at the Federal Aviation Administration's Airworthiness Assurance NDI Validation Center (AANC) to easily and rapidly detect hidden stress corrosion cracks in all vertical windshield posts on the US Coast Guard (USCG) HU-25 Guardian aircraft. The inspection procedure locates cracks as small as 2.0 millimeters emanating from internal fastener holes and determines their length. A test procedure was developed and a baseline assessment of the USCG fleet was conducted. Inspection results on twenty-five aircraft revealed a good correlation with results made during subsequent structural disassembly and visual inspection.

  11. Monitoring Cracking of a Smectitic Vertisol using Three-dimensional Electrical Resistivity Tomography

    E-Print Network [OSTI]

    Ackerson, Jason Paul

    2013-11-20T23:59:59.000Z

    Upon desiccation, the matrix of Vertisols and other expansive soils shrinks. Matrix shrinkage results in the formation of cracks that can alter the hydrology of the soil. Despite the importance of cracks, many hydrologic models do not account...

  12. E-Print Network 3.0 - assisted crack growth Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    cal crack growth by stress... for the first time in sapphire for both modes of subcritical cracking. It was found that growth rates were... growth rates could be closely...

  13. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

    using aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"ings of Aquifer Thermal Energy Storage Workshop, Lawrence

  14. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

    aquifers for thermal energy storage. Problems outlined aboveModeling of Thermal Energy Storage in Aquifers," Proceed-ings of Aquifer Thermal Energy Storage Workshop, Lawrence

  15. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

    using aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"Proceed- ings of Aquifer Thermal Energy Storage Workshop,

  16. E-Print Network 3.0 - amplitude fatigue crack Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with an initial crack. Constant ... Source: Fatemi, Ali - Department of Mechanical, Industrial and Manufacturing Engineering, University of Toledo Collection: Materials...

  17. NIH Public Policy Delay before Open

    E-Print Network [OSTI]

    Polz, Martin

    Publisher NIH Public Policy Compliance Delay before Open Access NIH Partner? Who Submits article American Physiological Society Yes 12 months Yes Publisher (author needs to report NIH funding) also offers stage (however, agreement allows for this posting at no cost for NIH funded articles) Cell Cycle

  18. Thin film cracking and ratcheting caused by temperature cycling

    E-Print Network [OSTI]

    Suo, Zhigang

    Thin film cracking and ratcheting caused by temperature cycling M. Huang and Z. Suo Mechanical caused by ratcheting in an adjacent ductile layer. For example, on a silicon die directly attached corners. Aided by cycling temperature, the shear stresses cause ratcheting in the aluminum pads

  19. Cracks and Atoms** By Dominic Holland* and Michael Marder

    E-Print Network [OSTI]

    Texas at Austin. University of

    Cracks and Atoms** By Dominic Holland* and Michael Marder 1. Introduction Many materials scientists the atomic scale on the mechanical response of materials. On the one hand, there is a reluctance to believe that the invisible atomic scale is important for macroscopic mechanical deformation. Out of sight, out of mind

  20. Method of making crack-free zirconium hydride

    DOE Patents [OSTI]

    Sullivan, Richard W. (Denver, CO)

    1980-01-01T23:59:59.000Z

    Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

  1. CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR

    E-Print Network [OSTI]

    CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR James R. Rice* ABSTRACT An exact linear elastic-perfectly plastic solution is presented for the problem of a sharp notch coordinates corresponding to given stresses, position of the elastic-plastic boundary, and accompanying

  2. MATHEMATICAL MODEL OF DELAMINATION CRACKS ON IMPERFECT INTERFACES

    E-Print Network [OSTI]

    Bath, University of

    monolith combustors that are being incorporated into new proto-type designs of gas turbines. The 1 #12. In the application in a gas turbine combustor, temperatures of the catalyst layer could vary from ambient conditionsMATHEMATICAL MODEL OF DELAMINATION CRACKS ON IMPERFECT INTERFACES Y. A. Antipov 1 , O. Avila

  3. Stress corrosion cracking under low stress: Continuous or discontinuous Longkui K. Zhu a

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Stress corrosion cracking under low stress: Continuous or discontinuous cracks? Longkui K. Zhu a , Yu Yan a , Jinxu X. Li a , Lijie J. Qiao a, , Alex A. Volinsky b,a a Corrosion and Protection Center. Stress corrosion C. Anodic dissolution a b s t r a c t Two-dimensional and three-dimensional crack

  4. Influence of Impurity Segregation on Temper Embrittlement and on Slow Fatigue Crack

    E-Print Network [OSTI]

    Ritchie, Robert

    of segregated impurity atoms (temper embrittlement) and hydrogen atoms, evolved from crack tip surface reactions with water vapor in the moist air environment (hydrogen embrittlement). The signifi- cance of crack closureInfluence of Impurity Segregation on Temper Embrittlement and on Slow Fatigue Crack Growth

  5. White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel!

    E-Print Network [OSTI]

    Cambridge, University of

    ! 1! White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel! ! W!phenomena!such!as!the!appearance!of!"white(etching!areas"!or!"white(etching! cracks",!crack!particular!kind!of!microstructural!damage!in!the!form!of!regions!of!the! structure,! which! appear! white! in

  6. A creep model for austenitic stainless steels incorporating cavitation and wedge cracking

    E-Print Network [OSTI]

    Mahesh, Sivasambu

    A creep model for austenitic stainless steels incorporating cavitation and wedge cracking S Mahesh evolution in the form of cavitation and wedge- cracking on grain boundary facets is considered. Both: Austenitic stainless steel, creep, grain boundary sliding, cavitation, wedge- cracking. Submitted to

  7. A new approach to the subcritical cracking of ceramic Pierre Ladev`eze,a,1

    E-Print Network [OSTI]

    A new approach to the subcritical cracking of ceramic fibers Pierre Ladev`eze,a,1 , Martin Geneta a Cachan Cedex, France Abstract A new modeling approach to subcritical crack propagation (i.e. static fa, the result comes down to the widely-used Paris-like subcritical crack propagation law. For the general case

  8. Average crack front velocity during subcritical fracture propagation in a heterogeneous medium

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Average crack front velocity during subcritical fracture propagation in a heterogeneous medium relaxation tests, exploring subcritical to critical regimes. Transparency of the material (PMMA) allows kinetic crack propagation is usually referred to as sub-critical crack growth or sub- critical regime

  9. On the physics of moisture-induced cracking in metal-glass ,,copper-silica... interfaces

    E-Print Network [OSTI]

    Ritchie, Robert

    September 2007 Environmentally dependent subcritical crack growth, or stress-corrosion cracking, along on the moisture content in gaseous environments. Water and several organic liquids, namely n-butanol, methanol, additionally, subcritical crack growth17 and cyclically induced fracture18 at or near these interfaces when

  10. Leakage Minimization Using Self Sensing and Thermal Alireza Vahdatpour

    E-Print Network [OSTI]

    Potkonjak, Miodrag

    architecture, measuring and modeling techniques, and algorithms for on-line power and energy optimization that can be used for real-time and low overhead measurement of temperature on chip positions where our Measurement, Design Keywords Leakage Energy, Thermal Management, Delay 1. INTRODUCTION There are two principal

  11. Thermal Stress Cracking of Sliding Gate Plates Hyoung-Jun Lee1

    E-Print Network [OSTI]

    Thomas, Brian G.

    , Warrendale, PA. #12;may b aspira b). Th indica show Previ their differ tempe mech [1]. A pressu be very

  12. Seven surrogate precursors for modeling delayed neutron decay and predicting reactivity

    SciTech Connect (OSTI)

    Loaiza, D.J.; Haskin, F.E.

    1997-12-31T23:59:59.000Z

    The use of a different set of group decay constants for each fissionable nuclide complicates analysis of the dynamic behavior of fast reactors. A fast reactor containing six principal fissioning nuclides of uranium and plutonium must, in effect, be described by 36 delayed neutron groups. Additionally, the use of group decay constants that depend on the neutron energy spectrum makes it difficult to select values that describe the dynamic response of epithermal systems because virtually all delayed neutron activity measurements have been performed for fast or thermal-neutron-induced fission. Clearly, it would be desirable to have a single set of group decay constants that could be applied to all fissionable nuclides. A set of seven fixed decay constants is proposed herein. Each of the proposed decay constants is associated with a specific, dominant delayed neutron precursor. In effect, each group is represented by a single surrogate precursor. Using recently measured delayed neutron activities for U-235 and Np-237, the proposed set of decay constants actually improved the goodness of fit to the data. For other fissionable nuclides lacking experimental data, a method has been devised to obtain yields consistent with the proposed set of decay constants from the traditional six-group parameters. This transformation is accomplished without altering the traditional inferred reactivity scale.

  13. Ultrasonic Flaw Detection of Cracks and Machined Flaws as Observed Through Austenitic Stainless Steel Piping Welds

    SciTech Connect (OSTI)

    Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.

    2009-07-01T23:59:59.000Z

    Piping welds in the pressure boundary of light water reactors (LWRs) are subject to a volumetric examination based on Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Due to access limitations and high background radiation levels, the technique used is primarily ultrasonic rather than radiographic. Many of the austenitic welds in safety-related piping systems provide limited access to both sides of the weld, so a far-side examination is necessary. Historically, far-side inspections have performed poorly because of the coarse and elongated grains that make up the microstructures of austenitic weldments. The large grains cause the ultrasound to be scattered, attenuated, and redirected. Additionally, grain boundaries or weld geometry may reflect coherent ultrasonic echoes, making flaw detection and discrimination a more challenging endeavor. Previous studies conducted at the Pacific Northwest National Laboratory (PNNL) on ultrasonic far-side examinations in austenitic piping welds involved the application of conventional transducers, use of low-frequency Synthetic Aperture Focusing Techniques (SAFT), and ultrasonic phased-array (PA) methods on specimens containing implanted thermal fatigue cracks and machined reflectors [1-2]. From these studies, PA inspection provided the best results, detecting nearly all of the flaws from the far side. These results were presented at the Fifth International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurised Components in 2006. This led to an invitation to examine field-removed specimens containing service-induced intergranular stress corrosion cracks (IGSCC) at the Electric Power Research Institute’s (EPRI) Nondestructive Evaluation (NDE) Center, in Charlotte, North Carolina. Results from this activity are presented.

  14. FURTHER EXAMINATION OF CRACK TIP MICROSTRUCTURES IN F82H ON THE LOWER SHELF

    SciTech Connect (OSTI)

    Gelles, David S.; Odette, George R.; Spatig, P.

    2003-09-03T23:59:59.000Z

    Dislocation microstructures have been further examined near the crack tip of a compact tension specimen of unirradiated F82H loaded to 25.6 MPa m square root at –196 degrees C after fatigue precracking. A specimen was prepared by sectioning, dimple grinding and ion milling to produce electron transparency just ahead of the crack tip. Further ion milling has allowed improved examination of the microstructure immediately ahead of the crack tip. It is found that subgrain structure is relatively unaffected near the crack tip whereas 3 micron from the crack tip, dislocation loop structure was identified.

  15. The effective delayed neutron fraction for bare-metal criticals

    SciTech Connect (OSTI)

    Pearlstein, S.

    1999-12-01T23:59:59.000Z

    Given sufficient material, a large number of actinides could be used to form bare-metal criticals. The effective delayed neutron fraction for a bare critical comprised of a fissile material is comparable with the absolute delayed neutron fraction. The effective delayed neutron fraction for a bare critical composed of a fissionable material is reduced by factors of 2 to 10 when compared with the absolute delayed neutron fraction. When the effective delayed neutron fraction is small, the difference between delayed and prompt criticality is small, and extreme caution must be used in critical assemblies of these materials. This study uses an approximate but realistic model to survey the actinide region to compare effective delayed neutron fractions with absolute delayed neutron fractions.

  16. A framework for delay emulation of large-scale internetworks

    E-Print Network [OSTI]

    Venkata, Shravan Rangaraju

    2001-01-01T23:59:59.000Z

    . The framework models and dynamically adapts the test traffic according to the network delay characteristics observed on the Internet in real-time. The proposed framework consists of three main modules: Virtual Host Configuration Module, Delay Estimator...

  17. Delay Analysis of Graphene Field-Effect Transistors

    E-Print Network [OSTI]

    Wang, Han

    In this letter, we analyze the carrier transit delay in graphene field-effect transistors (GFETs).The extraction of the intrinsic delay provides a new way to directly estimate carrier velocity from the experimental data, ...

  18. Characteristics of lead induced stress corrosion cracking of alloy 690 in high temperature

    SciTech Connect (OSTI)

    Chung, K.K. [Korea Inst. of Nuclear Safety, Taejon (Korea, Republic of); Lim, J.K. [Chonbuk National Univ., Chonju (Korea, Republic of); Watanabe, Yutaka; Shoji, Tetsuo [Tohoku Univ., Sendai (Japan). Research Inst. for Fracture Technology

    1996-10-01T23:59:59.000Z

    Slow strain rate tests (SSRT) were conducted on alloy 690 in various lead chloride solutions and metal lead added to 100 ppm chloride solution at 288 C. The corrosion potential (rest potential) for the alloy was measured with SSRT tests. The cracking was observed by metallographic examination and electron probe micro analyzer. Also, the corrosion behavior of the alloy was evaluated by anodic polarized measurement at 30 C. Resulting from the tests, cracking was characterized by cracking behavior, crack length and crack growth rate, and lead effects on cracking. The cracking was mainly intergranular in mode, approximately from 60 um to 450 um in crack length, and approximately 10{sup {minus}6} to 10{sup {minus}7} mmS-1 in crack velocity. The cracking was evaluated through the variation the corrosion potential in potential-time and lead behavior during SSRTs. The lead effect in corrosion was evaluated through active to passive transition behavior in anodic polarized curves. The corrosion reactions in the cracking region were confirmed by electron probe microanalysis. Alloy 690 is used for steam generation tubes in pressurized water reactors.

  19. q-deformed logistic map with delay feedback

    E-Print Network [OSTI]

    Manish Dev Shrimali; Subhashish Banerjee

    2012-03-14T23:59:59.000Z

    The delay logistic map with two types of q-deformations: Tsallis and Quantum-group type are studied. The stability of the map and its bifurcation scheme is analyzed as a function of the deformation and delay feedback parameters. Chaos is suppressed in a certain region of deformation and feedback parameter space. The steady state obtained by delay feedback is maintained in one type of deformation while chaotic behavior is recovered in another type with increasing delay.

  20. SRS delayed neutron instruments for safeguards measurements

    SciTech Connect (OSTI)

    Studley, R.V. [Westinghouse SRC, Aiken, SC (United States)

    1993-12-31T23:59:59.000Z

    Six analytical systems measuring delayed neutrons have been used for safeguards measurements at the Savannah River Site (SRS). A predecessor, the 252Cf Activation Analysis Facility installed at the Savannah River Technology Center (formally SR Laboratory) has been used since 1974 to analyze small samples, measuring both delayed neutrons and gammas. The six shufflers, plus one currently being fabricated, were developed, designed and fabricated by the LANL N-1 group. These shufflers have provided safeguards measurements of product (2 each), in-process scrap (2 each plus a conceptual replacement) and process waste (2 each plus one being fabricated). One shuffler for scrap assay was the first shuffler to be installed (1978) in a process. Another (waste) was the first installed in a process capable of assaying barrels. A third (waste) is the first pass-through model and a fourth (product) is the most precise ({+-}.12%) and accurate NDA instrument yet produced.

  1. Coherence delay augmented laser beam homogenizer

    DOE Patents [OSTI]

    Rasmussen, P.; Bernhardt, A.

    1993-06-29T23:59:59.000Z

    The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

  2. Method for reducing ignition delay of fuels

    SciTech Connect (OSTI)

    Hoppie, L.O.

    1984-05-15T23:59:59.000Z

    A method of reducing ignition delay /tau/, of fuels to negligible values and negligible differences is disclosed. Fuels conditioned to have such negligible values and differences are readily used in multiple fuel engines, such fuels self-ignite substantially instantaneously when injected into an oxidant, require substantially no heat transfer from the oxidant to effect the self-ignition, and the self-ignition is sufficient to sustain continued combustion.

  3. Coherence delay augmented laser beam homogenizer

    DOE Patents [OSTI]

    Rasmussen, Paul (Livermore, CA); Bernhardt, Anthony (Berkeley, CA)

    1993-01-01T23:59:59.000Z

    The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

  4. E-Print Network 3.0 - activation delay time Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Activity Analysis and PreLayout Activity Prediction for FPGAs Summary: activity on a net changes when delays are zero (zero delay activity) versus when logic delays... are...

  5. State Control Design for Linear Systems with Distributed Time Delays

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    State Control Design for Linear Systems with Distributed Time Delays Daniel Gontkovic and Róbert with distributed time delays. Using an extended form of the Lyapunov- Krasovskii functional the controller design involving distributed time delays is a problem of large practical interest where intensive activity are done

  6. Maximizing Crosstalk-Induced Slowdown During Path Delay Test

    E-Print Network [OSTI]

    Gope, Dibakar

    2012-10-19T23:59:59.000Z

    in path delay for c5315 .................................................................... 57 Figure 11 Increase in path delay for c2670 .................................................................... 60 Figure 12 Increase in path delay for c... for critical paths considering single aggressor crosstalk effect with due consideration to the timing alignment and direction. This method has similar CPU efficiency to that of [17] and [18]. However, they did not take into account the possible impact...

  7. Fatigue and Creep Crack Propagation behaviour of Alloy 617 in the Annealed and Aged Conditions

    SciTech Connect (OSTI)

    Julian K. Benz; Richard N. Wright

    2013-10-01T23:59:59.000Z

    The crack propagation behaviour of Alloy 617 was studied under various conditions. Elevated temperature fatigue and creep-fatigue crack growth experiments were conducted at 650 and 800 degrees C under constant stress intensity (triangle K) conditions and triangular or trapezoidal waveforms at various frequencies on as-received, aged, and carburized material. Environmental conditions included both laboratory air and characteristic VHTR impure helium. As-received Alloy 617 displayed an increase in the crack growth rate (da/dN) as the frequency was decreased in air which indicated a time-dependent contribution component in fatigue crack propagation. Material aged at 650°C did not display any influence on the fatigue crack growth rates nor the increasing trend of crack growth rate with decreasing frequency even though significant microstructural evolution, including y’ (Ni3Al) after short times, occurred during aging. In contrast, carburized Alloy 617 showed an increase in crack growth rates at all frequencies tested compared to the material in the standard annealed condition. Crack growth studies under quasi-constant K (i.e. creep) conditions were also completed at 650 degrees C and a stress intensity of K = 40 MPa9 (square root)m. The results indicate that crack growth is primarily intergranular and increased creep crack growth rates exist in the impure helium environment when compared to the results in laboratory air. Furthermore, the propagation rates (da/dt) continually increased for the duration of the creep crack growth either due to material aging or evolution of a crack tip creep zone. Finally, fatigue crack propagation tests at 800 degrees C on annealed Alloy 617 indicated that crack propagation rates were higher in air than impure helium at the largest frequencies and lowest stress intensities. The rates in helium, however, eventually surpass the rates in air as the frequency is reduced and the stress intensity is decreased which was not observed at 650 degrees C.

  8. Initiation of environmentally-assisted cracking in low-alloy steels

    SciTech Connect (OSTI)

    Wire, G.L.; Li, Y.Y.

    1996-06-01T23:59:59.000Z

    Environmentally-Assisted Cracking (EAC) in low alloy steels is activated by a critical level of sulfide ions at the crack tip, which is produced from dissolution of sulfide inclusions (MnS, FeS, etc.) in the steel following exposure by a growing crack. EAC of concern herein is the increase of fatigue crack growth rate of up to 40 to 100 times the rate in air that occurs at 240--300 C in high temperature LWR or boiler water environments. The initiation of EAC is the onset of the higher fatigue crack growth rates in fully developed cracks already presumed to be present due to fatigue, stress corrosion cracking, or induced by fabrication. Initiation of EAC is induced by a change in loading parameters causing the fatigue crack growth rate to increase from a small multiple (2--4) to 40--100 times the air rate. A steady state theory developed by Combrade, suggests that EAC will initiate only above a critical crack velocity and cease below this same velocity. However, more recent tests show that EAC can persist down to much lower velocities (100 times lower) in low oxygen water at slightly lower temperatures. A special set of experiments on high sulfur plate material demonstrate that EAC will not initiate from surface cracks with low sulfide inventories at low crack tip velocities. Transient diffusion calculations show that a finite crack extension at a high crack tip velocity is necessary to initiate EAC, providing a possible explanation for the lack of high crack growth observations reported in low alloy steels in structural applications involving low oxygen environments.

  9. Coupled heat conduction and thermal stress formulation using explicit integration. [LMFBR

    SciTech Connect (OSTI)

    Marchertas, A.H.; Kulak, R.F.

    1982-06-01T23:59:59.000Z

    The formulation needed for the conductance of heat by means of explicit integration is presented. The implementation of these expressions into a transient structural code, which is also based on explicit temporal integration, is described. Comparisons of theoretical results with code predictions are given both for one-dimensional and two-dimensional problems. The coupled thermal and structural solution of a concrete crucible, when subjected to a sudden temperature increase, shows the history of cracking. The extent of cracking is compared with experimental data.

  10. A few-group delayed neutron model based on a consistent set of decay constants

    SciTech Connect (OSTI)

    Campbell, J.M.; Spriggs, G.D.

    1998-01-22T23:59:59.000Z

    As part of an international effort, the Los Alamos National Laboratory has been asked to (1) determine if there is a set of dominant precursors that are common to all fissionable isotopes and all incident neutron energies, (2) expand the existing experimentally-measured few-group models commonly used in the nuclear industry into their 8-group equivalent using a consistent set of decay constants corresponding to these dominant precursors, and (3) formulate new group spectra for the equivalent 8-group model. In response to this request, LANL has calculated the theoretical delayed neutron yield for 14 different isotopes using three different incident neutron spectra (i.e., thermal, fast, and 14.1 MeV) using the current fission-yield and emission probability data found in ENDF-VI. An example of these results is shown in a figure in which the theoretical delayed neutron yields for the 271 precursors produced during thermal fission of {sup 235}U are plotted against the half-lives of the precursors. By comparing the results of all 14 isotopes, a preliminary set of precursors has been identified that are dominant within the various half-life regimes of the delayed neutron precursors. Also plotted on a figure are the group yields of the 8-group equivalent model of Keepin`s 6-group model. And finally, an example of the delayed neutron spectra for group 7 in the 8-group equivalent model is shown. A final report summarizing all results is expected to be released for review by the international steering committee by the summer of 1998.

  11. Environmentally assisted cracking of light-water reactor materials

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Kassner, T.F.; Shack, W.J.

    1996-02-01T23:59:59.000Z

    Environmentally assisted cracking (EAC) of lightwater reactor (LWR) materials has affected nuclear reactors from the very introduction of the technology. Corrosion problems have afflicted steam generators from the very introduction of pressurized water reactor (PWR) technology. Shippingport, the first commercial PWR operated in the United States, developed leaking cracks in two Type 304 stainless steel (SS) steam generator tubes as early as 1957, after only 150 h of operation. Stress corrosion cracks were observed in the heat-affected zones of welds in austenitic SS piping and associated components in boiling-water reactors (BRWs) as early as 1965. The degradation of steam generator tubing in PWRs and the stress corrosion cracking (SCC) of austenitic SS piping in BWRs have been the most visible and most expensive examples of EAC in LWRs, and the repair and replacement of steam generators and recirculation piping has cost hundreds of millions of dollars. However, other problems associated with the effects of the environment on reactor structures and components am important concerns in operating plants and for extended reactor lifetimes. Cast duplex austenitic-ferritic SSs are used extensively in the nuclear industry to fabricate pump casings and valve bodies for LWRs and primary coolant piping in many PWRs. Embrittlement of the ferrite phase in cast duplex SS may occur after 10 to 20 years at reactor operating temperatures, which could influence the mechanical response and integrity of pressure boundary components during high strain-rate loading (e.g., seismic events). The problem is of most concern in PWRs where slightly higher temperatures are typical and cast SS piping is widely used.

  12. Thermal conductivity of thermal-battery insulations

    SciTech Connect (OSTI)

    Guidotti, R.A.; Moss, M.

    1995-08-01T23:59:59.000Z

    The thermal conductivities of a variety of insulating materials used in thermal batteries were measured in atmospheres of argon and helium using several techniques. (Helium was used to simulate the hydrogen atmosphere that results when a Li(Si)/FeS{sub 2} thermal battery ages.) The guarded-hot-plate method was used with the Min-K insulation because of its extremely low thermal conductivity. For comparison purposes, the thermal conductivity of the Min-K insulating board was also measured using the hot-probe method. The thermal-comparator method was used for the rigid Fiberfrax board and Fiberfrax paper. The thermal conductivity of the paper was measured under several levels of compression to simulate the conditions of the insulating wrap used on the stack in a thermal battery. The results of preliminary thermal-characterization tests with several silica aerogel materials are also presented.

  13. SAES ST 909 PILOT SCALE METHANE CRACKING TESTS

    SciTech Connect (OSTI)

    Klein, J; Henry Sessions, H

    2007-07-02T23:59:59.000Z

    Pilot scale (500 gram) SAES St 909 methane cracking tests were conducted to determine material performance for tritium process applications. Tests that ran up to 1400 hours have been performed at 700 C, 202.7 kPa (1520 torr) with a 30 sccm feed of methane, with various impurities, in a 20 vol% hydrogen, balance helium, stream. A 2.5 vol% methane feed was reduced below 30 ppm for 631 hours. A feed of 1.1 vol% methane plus 1.4 vol% carbon dioxide was reduced below 30 ppm for 513 hours. The amount of carbon dioxide gettered by St 909 can be equated to an equivalent amount of methane gettered to estimate a reduced bed life for methane cracking. The effect of 0.4 vol % and 2.1 vol% nitrogen in the feed reduced the time to exceed 30 ppm methane to 362 and 45 hours, respectively, but the nitrogen equivalence to reduced methane gettering capacity was found to be dependent on the nitrogen feed composition. Decreased hydrogen concentrations increased methane getter rates while a drop of 30 C in one bed zone increased methane emissions by over a factor of 30. The impact of gettered nitrogen can be somewhat minimized if the nitrogen feed to the bed has been stopped and sufficient time given to recover the methane cracking rate.

  14. Delay time and Hartman effect in strain engineered graphene

    SciTech Connect (OSTI)

    Chen, Xi, E-mail: xchen@shu.edu.cn; Deng, Zhi-Yong [Department of Physics, Shanghai University, 200444 Shanghai (China); Ban, Yue, E-mail: yban@shu.edu.cn [Department of Electronic Information Materials, Shanghai University, 200444 Shanghai (China)

    2014-05-07T23:59:59.000Z

    Tunneling times, including group delay and dwell time, are studied for massless Dirac electrons transmitting through a one-dimensional barrier in strain-engineered graphene. The Hartman effect, the independence of group delay on barrier length, is induced by the strain effect, and associated with the transmission gap and the evanescent mode. The influence of barrier height/length and strain modulus/direction on the group delay is also discussed, which provides the flexibility to control the group delay with applications in graphene-based devices. The relationship between group delay and dwell time is finally derived to clarify the nature of the Hartman effect.

  15. Mixed-mode, high-cycle fatigue-crack growth thresholds in I. A comparison of large-and short-crack behavior

    E-Print Network [OSTI]

    Ritchie, Robert

    ) in a Ti±6Al±4V turbine blade alloy with a bimodal microstructure. Speci®cally, the eect of combined mode I machined to within $200 lm of the precrack tip. For such short cracks, wherein the magnitude of crack, particularly in association with fretting fatigue in the blade dovetail/disk contact section [3]. For fatigue

  16. Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods

    SciTech Connect (OSTI)

    Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Denslow, Kayte M.; Diaz, Aaron A.; Doctor, Steven R.

    2007-03-01T23:59:59.000Z

    Studies conducted at the Pacific Northwest National Laboratory in Richland, Washington, have focused on assessing the effectiveness and reliability of novel approaches to nondestructive examination (NDE) for inspecting coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the U.S. Nuclear Regulatory Commission on the effectiveness and reliability of advanced NDE methods as related to the inservice inspection of safety-related components in pressurized water reactors (PWRs). This report provides progress, recent developments, and results from an assessment of low frequency ultrasonic testing (UT) for detection of inside surface-breaking cracks in cast stainless steel reactor piping weldments as applied from the outside surface of the components. Vintage centrifugally cast stainless steel piping segments were examined to assess the capability of low-frequency UT to adequately penetrate challenging microstructures and determine acoustic propagation limitations or conditions that may interfere with reliable flaw detection. In addition, welded specimens containing mechanical and thermal fatigue cracks were examined. The specimens were fabricated using vintage centrifugally cast and statically cast stainless steel materials, which are typical of configurations installed in PWR primary coolant circuits. Ultrasonic studies on the vintage centrifugally cast stainless steel piping segments were conducted with a 400-kHz synthetic aperture focusing technique and phased array technology applied at 500 kHz, 750 kHz, and 1.0 MHz. Flaw detection and characterization on the welded specimens was performed with the phased array method operating at the frequencies stated above. This report documents the methodologies used and provides results from laboratory studies to assess baseline material noise, crack detection, and length-sizing capability for low-frequency UT in cast stainless steel piping.

  17. Microstructural and solidification cracking evaluation of electron beam welds in 304L

    SciTech Connect (OSTI)

    Sturgill, P.L.; Campbell, R.D.; Henningsen, J.L.

    1991-01-01T23:59:59.000Z

    Weld hot cracking of stainless steels is a major materials-related problem in the welding industry. This present investigation evaluates the crack susceptibility of highly-constrained EB welds made in materials whose DeLong ferrite potentials range from zero to nine FN. In addition, the effect of piece part strength level on cracking is examined. This study has revealed that these deep penetration EB welds have regions that solidify as primary austenite, even when the DeLong ferrite potential is as high as 9 FN. This points out the critical role that solidification rate plays in the crack susceptibility of these highly restrained welds. In addition, 0 FN to 0 FN welds had primarily transverse cracks while 6 FN to 0 FN welds had primarily centerline cracks. Of particular interest is the observation that cracks still occur if a high ferrite (greater than 6 FN) component is welded to a zero FN component. Cracking is always associated with regions which solidify as primary austenite and these cracks occur because there are areas in the weld which do not mix. Thus it is not a recommended production practice to compensate for low ferrite in one piece part with high ferrite in its mate. Finally, it is shown that a DeLong FN threshold of 4 to prevent cracking in EB welds in not valid. 21 refs., 16 figs.

  18. Stress Corrosion Cracking and Non-Destructive Examination of Dissimilar Metal Welds and Alloy 600

    SciTech Connect (OSTI)

    Jackson, Deborah A. [U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001 (United States)

    2002-07-01T23:59:59.000Z

    The United States Nuclear Regulatory Commission (USNRC) has conducted research since 1977 in the areas of environmentally assisted cracking and assessment and reliability of non-destructive examination (NDE). Recent occurrences of cracking in Alloy 82/182 welds and Alloy 600 base metal at several domestic and overseas plants have raised several issues relating to both of these areas of NRC research. The occurrences of cracking were identified by the discovery of boric acid deposits resulting from through-wall cracking in the primary system pressure boundary. Analyses indicate that the cracking has occurred due to primary water stress corrosion cracking (PWSCC) in Alloy 82/182 welds. This cracking has occurred in two different locations: in hot leg nozzle-to-safe end welds and in control rod drive mechanism (CRDM) nozzle welds. The cracking associated with safe-end welds is important due to the potential for a large loss of reactor coolant inventory, and the cracking of CRDM nozzle base metal and welds, particularly circumferential cracking of CRDM nozzle base metal, is important due to the potential for a control rod to eject resulting in a loss of coolant accident. The industry response in the U.S. to this cracking is being coordinated through the Electric Power Research Institute's Materials Reliability Project (EPRI-MRP) in a comprehensive, multifaceted effort. Although the industry program is addressing many of the issues raised by these cracking occurrences, confirmatory research is necessary for the staff to evaluate the work conducted by industry groups. Several issues requiring additional consideration regarding the generic implications of these isolated events have been identified. This paper will discuss the recent events of significant cracking in domestic and foreign plants, discuss the limitations of NDE in detecting SCC, identify deficiencies in information available in this area, discuss the USNRC approach to address these issues, and discuss the development of an international cooperative effort. (authors)

  19. Fatigue Crack Propagation from Notched Specimens of 304 SS in elevated Temperature Aqueous Environment

    SciTech Connect (OSTI)

    Wire, G. L.; Mills, W. J.

    2002-08-01T23:59:59.000Z

    Fatigue crack propagation (FCP) rates for 304 stainless steel (304SS) were determined in 24 degree C and 288 degree C air and 288 degree C water using double-edged notch (DEN) specimens of 304 stainless steel (304 SS). Test performed at matched loading conditions in air and water at 288 degree C with 20-6- cc h[sub]2/kg h[sub]2O provided a direct comparison of the relative crack growth rates in air and water over a wide range of crack growth rates. The DEN crack extension ranged from short cracks (0.03-0.25 mm) to long cracks up to 4.06 mm, which are consistent with conventional deep crack tests. Crack growth rates of 304 SS in water were about 12 times the air rate. This 12X environmental enhancement persisted to crack extensions up to 4.06 mm, far outside the range associated with short crack effects. The large environmental degradation for 304 SS crack growth is consistent with the strong reduction of fatigue life in high hydrogen water. Further, very similar environmental effects w ere reported in fatigue crack growth tests in hydrogen water chemistry (HWC). Most literature data in high hydrogen water show only a mild environmental effect for 304 SS, of order 2.5 times air or less, but the tests were predominantly performed at high cyclic stress intensity or equivalently, high air rates. The environmental effect in low oxygen environments at low stress intensity depends strongly on both the stress ratio, R, and the load rise time, T[sub]r, as recently reported for austenitic stainless steel in BWR water. Fractography was performed for both tests in air and water. At 288 degree C in water, the fracture surfaces were crisply faceted with a crystallographic appearance, and showed striations under high magnification. The cleavage-like facets on the fracture surfaces suggest that hydrogen embrittlement is the primary cause of accelerated cracking.

  20. High Temperature Thermal Array for Next Generation Solar Thermal...

    Broader source: Energy.gov (indexed) [DOE]

    High Temperature Thermal Array for Next Generation Solar Thermal Power Production High Temperature Thermal Array for Next Generation Solar Thermal Power Production This...

  1. The Thermal Expansion, Elastic and Fracture Properties of Porous Cordierite at Elevated Temperatures

    SciTech Connect (OSTI)

    Shyam, Amit [ORNL; Lara-Curzio, Edgar [ORNL; Pandey, Amit [ORNL; Watkins, Thomas R [ORNL; More, Karren [Oak Ridge National Laboratory (ORNL)

    2012-01-01T23:59:59.000Z

    The properties that determine the thermal shock resistance in materials are reported for porous cordierite, a leading candidate material for the fabrication of diesel particulate filters. Fracture toughness and slow crack growth tests were performed on test specimens obtained from the walls of diesel particulate filter monolithic substrates using the double-torsion test method at temperatures between 20 C and 900 C. The thermal expansion and elastic properties were characterized between 20 C and 1000 C. The role of the microstructure of porous cordierite in determining its unusual thermal expansion and elevated temperature Young's modulus and fracture toughness are discussed.

  2. -delayed proton emission branches in 43Cr

    SciTech Connect (OSTI)

    Pomorski, M. [University of Warsaw; Miernik, K. [University of Warsaw; Dominik, W. [University of Warsaw; Janas, Z. [University of Warsaw; Pfutzner, M. [University of Warsaw; Bingham, C. R. [University of Tennessee, Knoxville (UTK); Czyrkowski, H. [University of Warsaw; Cwiok, Mikolaj [Warsaw University; Darby, Iain [University of Tennessee, Knoxville (UTK); Dabrowski, Ryszard [Warsaw University; Ginter, T. N. [Michigan State University, East Lansing; Grzywacz, Robert Kazimierz [ORNL; Karny, M. [University of Warsaw; Korgul, A. [University of Warsaw; Kusmierz, W. [University of Warsaw; Liddick, Sean [University of Tennessee, Knoxville (UTK); Rajabali, M. M. [University of Tennessee, Knoxville (UTK); Rykaczewski, Krzysztof Piotr [ORNL; Stolz, A. [Michigan State University, East Lansing

    2011-01-01T23:59:59.000Z

    The + decay of very neutron-deficient 43Cr was studied by means of an imaging time projection chamber that allowed recording tracks of charged particles. Events of -delayed emission of one, two, and three protons were clearly identified. The absolute branching ratios for these channels were determined to be (81 4)%, (7.1 0.4)%, and (0.08 0.03)%, respectively. 43Cr is thus established as the second case in which the -3p decay occurs. Although the feeding to the proton-bound states in 43V is expected to be negligible, the large branching ratio of (12 4)% for decays without proton emission is found.

  3. Seasonal thermal energy storage

    SciTech Connect (OSTI)

    Allen, R.D.; Kannberg, L.D.; Raymond, J.R.

    1984-05-01T23:59:59.000Z

    This report describes the following: (1) the US Department of Energy Seasonal Thermal Energy Storage Program, (2) aquifer thermal energy storage technology, (3) alternative STES technology, (4) foreign studies in seasonal thermal energy storage, and (5) economic assessment.

  4. Subcritical Crack Growth in Ceramic Composites at High Temperature Measured Using Digital Image Correlation

    SciTech Connect (OSTI)

    Mumm, D.R.; Morris, W.L.; Dadkhah, M.S.; Cox, B.N.

    1996-01-11T23:59:59.000Z

    An in situ experimental technique is described that allows high resolution, high sensitivity determination of displacements and full-field strains during high temperature mechanical testing. The technique is used to investigate elevated temperature crack growth in SiC/Nicalon sub f composites. At 1150 degrees C, the reinforcing fibers have a higher creep susceptibility than the matrix. Fiber creep leads to relaxation of crack bridging tractions, resulting in subcritical crack growth. Differential image analysis is used to measure the crack opening displacement profile u(x) of an advancing, bridged crack. With appropriate modeling, such data can be used to determine the traction law, from which the mechanics of cracking and failure may be determined.

  5. Thermal unobtainiums? The perfect thermal conductor and

    E-Print Network [OSTI]

    Braun, Paul

    contribute to thermal resistance · Isotopically pure diamond has highest thermal conductivity of any material materials: disordered layered crystals Conclude with some thoughts on promising, high-risk, research even in a computer model. #12;Thermal resistance is created by Umklapp scattering (U

  6. Thermal Control & System Integration

    Broader source: Energy.gov [DOE]

    The thermal control and system integration activity focuses on issues such as the integration of motor and power control technologies and the development of advanced thermal control technologies....

  7. Significance of crack opening monitoring for determining the growth behavior of hydrofractures

    SciTech Connect (OSTI)

    Hashida, Toshiyuki; Sato, Kazushi; Takahashi, Hideaki

    1993-01-28T23:59:59.000Z

    A method for determining the size of a crack induced by hydraulic fracturing is presented. The procedure is based on the measurement of the crack opening displacement and the fracture mechanics approach. The proposed method has been tested by conducting laboratory small-scale hydraulic fracturing tests on a granite. It is shown from the preliminary tests that the method provides a reasonable prediction of experimentally observed crack sizes.

  8. Delayed neutron detection with an integrated differential die-away and delayed neutron instrument

    SciTech Connect (OSTI)

    Blanc, Pauline [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory; Lee, Taehoon [Los Alamos National Laboratory; Hu, Jianwei S [Los Alamos National Laboratory; Hendricks, John [Los Alamos National Laboratory; Croft, Stephen [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    The Next Generation Safeguards Initiative (NGSI) of the U.S. Department of Energy (DOE) has funded a multilab/university collaboration to quantify the plutonium (Pu) mass and detect the diversion of pins from spent nuclear fuel. The first two years of this NGSI effort was focused on quantifying the capability of a range of nondestructive assay (NDA) techniques with Monte Carlo (MCNPX) modeling and the second current phase involves measuring Spent Fuel. One of the techniques of interest in this paper involves measuring delayed neutrons. A delayed neutron instrument using 36 fission chambers and a 14 MeV neutron generator so called DT generator (Deuterium + Tritium) surrounding the fuel was previously studied as part of the NGSI effort. This paper will quantify the capability of a standalone delayed neutron instrument using 4 {sup 3}He gas filled tubes and a DT generator with significant spectrum tailoring, located far from the fuel. So that future research can assess how well a delayed neutron instrument will function as part of an integrated NDA system. A new design is going to be used to respond to the need of the techniques. This design has been modeled for a water media and is currently being optimized for borated water and air media as part of ongoing research. This new design was selected in order to minimize the fission of {sup 238}U, to use a more realistic neutron generator design in the model, to reduce cost and facilitate the integration of a delayed neutron (DN) with a differential die-away (DDA) instrument. Since this paper will focus on delayed neutron detection, the goal is to quantify the signal from {sup 235}U, {sup 239}Pu and {sup 241}Pu, which are the isotopes present in Spent Fuel that respond significantly to a neutron interrogation. This report will quantify the capability of this new delayed neutron design to measure the combined mass of {sup 235}U, {sup 239}Pu and {sup 241}Pu for 16 of the 64 assemblies of the NGSI Spent Fuel library in one of the three media, water.

  9. Stress-corrosion cracking of steels in ammonia with consideration given to OTEC design: a survey

    SciTech Connect (OSTI)

    Teel, R.B.

    1980-03-01T23:59:59.000Z

    Carbon steel, alloy steel, and high-strength, quenched and tempered steel, when under applied or residual stress and especially when cold formed and/or welded without subsequent thermal stress relief, are subject to failure by stress-corrosion cracking (SCC) in air-contaminated dry ammonia. Water as well as hydrazine when present in small amounts have been shown to be effective inhibitors in an all steel system. Galvanic corrosion between dissimilar metals and/or accelerated failure by SCC of stressed steel as a result of galvanic coupling may be of concern. Where water has proven effective as an inhibitor of SCC in an all steel system, it may not be adequate in a mixed metal system. With aluminum tubes, the tube sheet will either have to be solid aluminum, aluminum clad steel or some nonconductive coating will be necessary to effectively remove the cathodic alloy from the galvanic circuit. Research is required to determine the severity of the coupling effect between dissimilar alloys in ammonia under OTEC conditions; especially the possibility of accelerated SCC failures of stressed steel where the presence of an inhibitor in the ammonia may not be sufficient to override the galvanic coupling effect.

  10. Evaluation of low-cycle fatigue crack growth and subsequent ductile fracture for cracked pipe experiments using cyclic J-integral

    SciTech Connect (OSTI)

    Miura, Naoki; Fujioka, Terutaka; Kashima, Koichi [CRIEPI, Tokyo (Japan); Miyazaki, Katsumasa; Kanno, Satoshi; Hayashi, Makoto; Ishiwata, Masayuki; Gotoh, Nobuho [Hitachi, Ltd., Ibaraki (Japan)

    1996-12-01T23:59:59.000Z

    Piping for LWR power plants is required to satisfy the Leak-Before-Break concept for postulated (not actual) defects. With this in mind, numerous research has so far been conducted on the fatigue crack growth under cyclic loading, and on the ductile crack growth under excessive loading. Study on cracked pipe fracture under cyclic loading gains much attention from the viewpoint of the Leak-Before-Break concept for seismic loading that accompanies large-scale yielding. An evaluation method based on cyclic J-integral was newly developed to predict the low-cycle fatigue crack growth and the subsequent ductile fracture for cyclic loading that accompanies large-scale yielding. Cyclic J-integral was introduced to describe the crack growth up to failure. The method was applied to 4-inch diameter circumferentially through-wall-cracked carbon steel base metal pipes and welded pipe joints subjected to cyclic 4-point bending at room temperature and high temperature of approximately 300 C. Fatigue crack growth behavior and failure life were successfully predicted by the proposed approach.

  11. Assessment and prediction of drying shrinkage cracking in bonded mortar overlays

    SciTech Connect (OSTI)

    Beushausen, Hans, E-mail: hans.beushausen@uct.ac.za; Chilwesa, Masuzyo

    2013-11-15T23:59:59.000Z

    Restrained drying shrinkage cracking was investigated on composite beams consisting of substrate concrete and bonded mortar overlays, and compared to the performance of the same mortars when subjected to the ring test. Stress development and cracking in the composite specimens were analytically modeled and predicted based on the measurement of relevant time-dependent material properties such as drying shrinkage, elastic modulus, tensile relaxation and tensile strength. Overlay cracking in the composite beams could be very well predicted with the analytical model. The ring test provided a useful qualitative comparison of the cracking performance of the mortars. The duration of curing was found to only have a minor influence on crack development. This was ascribed to the fact that prolonged curing has a beneficial effect on tensile strength at the onset of stress development, but is in the same time not beneficial to the values of tensile relaxation and elastic modulus. -- Highlights: •Parameter study on material characteristics influencing overlay cracking. •Analytical model gives good quantitative indication of overlay cracking. •Ring test presents good qualitative indication of overlay cracking. •Curing duration has little effect on overlay cracking.

  12. Mixed Mode Static and Fatigue Crack Growth in Wind Blade Paste Adhesives

    E-Print Network [OSTI]

    , static GIc and mixed mode fracture, and fatigue crack growth resistance. I. Introduction Wind turbine blades are large composite structures which are typically resin infusion molded in sections

  13. Modeling of interaction between corrosion-induced concrete cover crack and steel corrosion rate.

    E-Print Network [OSTI]

    Cao, Chong

    2012-01-01T23:59:59.000Z

    ??Chloride-induced corrosion of steel reinforcement in concrete may cause severe damage to RC structures. Longitudinal cover cracks may form during the rust expansion process. Currently,… (more)

  14. Effects of weld residual stresses on crack-opening area analysis of pipes for LBB applications

    SciTech Connect (OSTI)

    Dong, P.; Rahman, S.; Wilkowski, G. [and others

    1997-04-01T23:59:59.000Z

    This paper summarizes four different studies undertaken to evaluate the effects of weld residual stresses on the crack-opening behavior of a circumferential through-wall crack in the center of a girth weld. The effect of weld residual stress on the crack-opening-area and leak-rate analyses of a pipe is not well understood. There are no simple analyses to account for these effects, and, therefore, they are frequently neglected. The four studies involved the following efforts: (1) Full-field thermoplastic finite element residual stress analyses of a crack in the center of a girth weld, (2) A comparison of the crack-opening displacements from a full-field thermoplastic residual stress analysis with a crack-face pressure elastic stress analysis to determine the residual stress effects on the crack-opening displacement, (3) The effects of hydrostatic testing on the residual stresses and the resulting crack-opening displacement, and (4) The effect of residual stresses on crack-opening displacement with different normal operating stresses.

  15. E-Print Network 3.0 - alligator cracking Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    search results for: alligator cracking Page: << < 1 2 3 4 5 > >> 1 Project Summary Report 7-4975-S PROJECTSUMMARYREPORT CENTER FOR TRANSPORTATION RESEARCH Summary: . For...

  16. Innovative Approach to Establish Root Causes for Cracking in Aggressive Reactor Environments

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Thomas, Larry E.; Vetrano, John S.; Simonen, Edward P.

    2003-10-31T23:59:59.000Z

    The research focuses on the high-resolution characterization of degradation microstructures and microchemistries in specimens tested under controlled conditions for the environment and for the material where in-service complexities can be minimized. Thermodynamic and kinetic modeling of crack-tip processes is employed to analyze corrosion-induced structures and gain insights into degradation mechanisms. Novel mechanistic ''fingerprinting'' of crack-tip structures is used to isolate causes of environmental cracking in tandem with quantitative measurements of crack growth. Sample preparation methods and advanced analytical techniques are used to characterize corrosion/oxidation reactions and crack-tip structures at near atomic dimensions in order to gain insight into fundamental environmental cracking mechanisms. Reactions at buried interfaces, not accessible by conventional approaches, are being systematically interrogated. Crack-growth experiments in high-temperature water environments are evaluating and isolating the effects of material condition (matrix strength, grain boundary composition and precipitation) on stress corrosion cracking (SCC). The fundamental understanding of crack advance mechanisms will establish the basis to design new corrosion-resistant alloys for current light-water reactors and advanced reactor systems.

  17. E-Print Network 3.0 - assisted fatigue crack Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Grain-Boundary Adhesion Summary: unless they experience environmentally assisted subcritical growth during cyclic loading.7 Fatigue-crack... (moist air and dry N2). The...

  18. Simulation of the ultrasonic array response from real branched cracks using an efficient finite element method

    SciTech Connect (OSTI)

    Felice, Maria V. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, United Kingdom and Rolls-Royce plc., Bristol BS34 7QE (United Kingdom); Velichko, Alexander; Wilcox, Paul D. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Barden, Tim J.; Dunhill, Tony K. [Rolls-Royce plc., Bristol BS34 7QE (United Kingdom)

    2014-02-18T23:59:59.000Z

    A hybrid model to simulate the ultrasonic array response from stress corrosion cracks is presented. These cracks are branched and difficult to detect so the model is required to enable optimization of an array design. An efficient frequency-domain finite element method is described and selected to simulate the ultrasonic scattering. Experimental validation results are presented, followed by an example of the simulated ultrasonic array response from a real stress corrosion crack whose geometry is obtained from an X-ray Computed Tomography image. A simulation-assisted array design methodology, which includes the model and use of real crack geometries, is proposed.

  19. Reactivity impact of delayed neutron spectra on MCNP calculations

    SciTech Connect (OSTI)

    Mosteller, R.D.; Werner, C.J.

    2000-07-01T23:59:59.000Z

    The new features in MCNP4C, the latest version of the MCNP Monte Carlo code, include the capability to sample from delayed as well as prompt fission emission spectra. Previous versions of MCNP all have sampled exclusively from prompt spectra. Delayed neutrons typically account for <1% of all neutrons emitted from fission, but the emission spectra for delayed neutrons are somewhat softer than those for prompt neutrons. Because of the softer spectrum, delayed neutrons are less likely to leak from the system, and they also are less likely to cause fission in isotopes that have an effective threshold for fission (e.g., {sup 238}U and {sup 240}Pu). Consequently, the inclusion of delayed neutron spectra can have a small but significant effect on reactivity calculations. This study performs MCNP4C calculations for a series of established benchmarks and quantifies the reactivity impact of the delayed neutron spectra.

  20. Thermal barrier coating resistant to sintering

    DOE Patents [OSTI]

    Subramanian, Ramesh; Seth, Brig B.

    2005-08-23T23:59:59.000Z

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process. The sintering inhibiting material (22) has a morphology adapted to improve the functionality of the sintering inhibiting material (22), characterized as continuous, nodule, rivulet, grain, crack, flake and combinations thereof and being disposed within at least some of the vertical and horizontal gaps.

  1. Nonlinear FE analysis of cracks in tension and shear

    E-Print Network [OSTI]

    Kesse, G.; Lees, Janet M.

    2007-05-01T23:59:59.000Z

    Carbon FRP Shear Reinforcement. PhD thesis, University of Cambridge, UK, 2003. 3. Bazant Z. P. and Planas J. Fracture and Size Effect in Con- crete and Other Quasibrittle Materials. CRC Press, Boca Raton, Florida, 1998. Nonlinear FE analysis of cracks... of plain concrete to cyclic tension. ACI Materials Journal, 1987, 84, No. 5, 365–373. 9. Paulay T. and Loeber P. J. Shear transfer by aggregate inter- lock. ACI Special Publication, SP-42, 1974, 1, 1–14. 10. Houde J. and Mirza M. S. A finite element...

  2. On the approximation of crack shapes found during inservice inspection

    SciTech Connect (OSTI)

    Bhate, S.R.; Chawla, D.S.; Kushwaha, H.S. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01T23:59:59.000Z

    This paper addresses the characterization of axial internal flaw found during inservice inspection of a pipe. J-integral distribution for various flaw shapes is obtained using line spring finite, element method. The peak J-value and its distribution across the crack is found to be characteristic feature of each shape. The triangular shape yields peak J-value away from the center, the point of depth. The elliptic approximation results in large overestimate of J-value for unsymmetric flaws. Triangular approximation is recommended for such flaws so that further service can be obtained from the component.

  3. Experimental control of chaos by variable and distributed delay feedback

    E-Print Network [OSTI]

    Thomas Jüngling; Aleksandar Gjurchinovski; Viktor Urumov

    2012-02-02T23:59:59.000Z

    We report on a significant improvement of the classical time-delayed feedback control method for stabilization of unstable periodic orbits or steady states. In an electronic circuit experiment we were able to realize time-varying and distributed delays in the control force leading to successful control for large parameter sets including large time delays. The presented technique makes advanced use of the natural torsion of the orbits, which is also necessary for the original control method to work.

  4. arabidopsis delays leaf: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    mediated by delayed responses Katul, Gabriel 4 Chloroplast protein degradation during natural leaf senescence in Arabidopsis thaliana. Open Access Theses and Dissertations...

  5. Thermal Management of Solar Cells

    E-Print Network [OSTI]

    Saadah, Mohammed Ahmed

    2013-01-01T23:59:59.000Z

    a better thermal conductance and when ceramic particles areor ceramic fillers that enhances thermal conductivity. Solid

  6. Delayed neutrons measurement at the MEGAPIE target

    E-Print Network [OSTI]

    Stefano Panebianco; Pavel Bokov; Diane Dore; Xavier Ledoux; Alain Letourneau; Aurelien Prevost; Danas Ridikas

    2007-05-25T23:59:59.000Z

    In the framework of the Neutronic and Nuclear Assessment Task Group of the MEGAPIE experiment we measured the delayed neutron (DN) flux at the top of the target. The measurement was proposed mainly for radioprotection purposes since the DN flux at the top of the target has been estimated to be of the same order of magnitude as the prompt neutron flux. Given the strong model-dependence of DN predictions, the measurement of DN contribution to the total neutron activity at the top of the target was thus desired. Moreover, this measurement is complementary to the DN experiments performed at PNPI (Gatchina) on solid lead and bismuth targets. The DN measurement at MEGAPIE was performed during the start-up phase of the target. In this paper we present a detailed description of the experimental setup and some preliminary results on decay spectra.

  7. Delayed neutrons measurement at the MEGAPIE target

    E-Print Network [OSTI]

    Panebianco, Stefano; Dore, Diane; Ledoux, Xavier; Letourneau, Alain; Prevost, Aurelien; Ridikas, Danas

    2007-01-01T23:59:59.000Z

    In the framework of the Neutronic and Nuclear Assessment Task Group of the MEGAPIE experiment we measured the delayed neutron (DN) flux at the top of the target. The measurement was proposed mainly for radioprotection purposes since the DN flux at the top of the target has been estimated to be of the same order of magnitude as the prompt neutron flux. Given the strong model-dependence of DN predictions, the measurement of DN contribution to the total neutron activity at the top of the target was thus desired. Moreover, this measurement is complementary to the DN experiments performed at PNPI (Gatchina) on solid lead and bismuth targets. The DN measurement at MEGAPIE was performed during the start-up phase of the target. In this paper we present a detailed description of the experimental setup and some preliminary results on decay spectra.

  8. Delayed neutron alignment in sup 117 I

    SciTech Connect (OSTI)

    Paul, E.S.; Waring, M.P.; Clark, R.M.; Forbes, S.A.; Fossan, D.B.; Hughes, J.R.; LaFosse, D.R.; Liang, Y.; Ma, R.; Vaska, P.; Wadsworth, R. (Oliver Lodge Laboratory, University of Liverpool, P.O. Box 147, Liverpool L69 3BX (United Kingdom) Department of Physics, State University of New York at Stony Brook, Stony Brook, New York 11794 (United States) Department of Physics, University of York, Heslington, York YO1 5DD (United Kingdom) Medical Department, Brookhaven National Laboratory, Upton, New York 11973 (United States))

    1992-06-01T23:59:59.000Z

    The rotational alignment of {ital h}{sub 11/2} neutrons is considerably delayed ({Delta}{h bar}{omega}{similar to}0.11 MeV) in the {pi}{ital h}{sub 11/2}(550)1/2{sup {minus}} intruder band in {sup 117}I when compared to bands built on normal-parity states. Comparison with cranked shell-model calculations suggests that this effect may indicate a larger quadrupole deformation for the intruder orbital. A strong neutron-proton interaction between the aligning {ital h}{sub 11/2} neutrons and the {ital h}{sub 11/2} proton intruder may also play a role. In addition, noncollective oblate states at {ital I}{sup {pi}}=39/2{sup {minus}},43/2{sup {minus}}, and 45/2{sup {minus}} compete energetically with rotational states of the intruder band which may also perturb the neutron alignment.

  9. Scattering and; Delay, Scale, and Sum Migration

    SciTech Connect (OSTI)

    Lehman, S K

    2011-07-06T23:59:59.000Z

    How do we see? What is the mechanism? Consider standing in an open field on a clear sunny day. In the field are a yellow dog and a blue ball. From a wave-based remote sensing point of view the sun is a source of radiation. It is a broadband electromagnetic source which, for the purposes of this introduction, only the visible spectrum is considered (approximately 390 to 750 nanometers or 400 to 769 TeraHertz). The source emits an incident field into the known background environment which, for this example, is free space. The incident field propagates until it strikes an object or target, either the yellow dog or the blue ball. The interaction of the incident field with an object results in a scattered field. The scattered field arises from a mis-match between the background refractive index, considered to be unity, and the scattering object refractive index ('yellow' for the case of the dog, and 'blue' for the ball). This is also known as an impedance mis-match. The scattering objects are referred to as secondary sources of radiation, that radiation being the scattered field which propagates until it is measured by the two receivers known as 'eyes'. The eyes focus the measured scattered field to form images which are processed by the 'wetware' of the brain for detection, identification, and localization. When time series representations of the measured scattered field are available, the image forming focusing process can be mathematically modeled by delayed, scaled, and summed migration. This concept of optical propagation, scattering, and focusing have one-to-one equivalents in the acoustic realm. This document is intended to present the basic concepts of scalar scattering and migration used in wide band wave-based remote sensing and imaging. The terms beamforming and (delayed, scaled, and summed) migration are used interchangeably but are to be distinguished from the narrow band (frequency domain) beamforming to determine the direction of arrival of a signal, and seismic migration in which wide band time series are shifted but not to form images per se. Section 3 presents a mostly graphically-based motivation and summary of delay, scale, and sum beamforming. The model for incident field propagation in free space is derived in Section 4 under specific assumptions. General object scattering is derived in Section 5 and simplified under the Born approximation in Section 6. The model of this section serves as the basis in the derivation of time-domain migration. The Foldy-Lax, full point scatterer scattering, method is derived in Section 7. With the previous forward models in hand, delay, scale, and sum beamforming is derived in Section 8. Finally, proof-of-principle experiments are present in Section 9.

  10. Optically controlled delays for broadband pulses

    E-Print Network [OSTI]

    Sun, Q. Q.; Rostovtsev, Y. V.; Dowling, J. P.; Scully, Marlan O.; Zubairy, M. Suhail

    2005-01-01T23:59:59.000Z

    susceptibility is given by #4;#1;#1;#5;p#2; #12; ? #6;#7;#8;p #5; #5;2 . #1;7#2; Therefore, at a position z, the delayed probe pulse is given by p#1;t,z#2; = p0 exp ? #1;t ? z/vg#2;22T2 , #1;8#2; where the group velocity of the optical pulse is vg#12... Security Agency, and the Army Research Office. #3;1#4; T. Kamiya, F. Saito, O. Wada, and H. Yajima, Femtosecond Technology #1;Springer, Berlin, 1999#2;. #3;2#4; S. E. Harris and L. V. Hau, Phys. Rev. Lett. 82, 4611 #1;1999#2;; P. C. Ku, C. J. Chang...

  11. Prediction of PWSCC in nickel base alloys using crack growth rate models

    SciTech Connect (OSTI)

    Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L. [Knolls Atomic Power Lab., Schenectady, NY (United States)

    1995-12-31T23:59:59.000Z

    The Ford/Andresen slip-dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material conditions. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip-dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip-dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

  12. Fatigue and environmentally assisted cracking in light water reactors

    SciTech Connect (OSTI)

    Kassner, T.F.; Ruther, W.E.; Chung, H.M.; Hicks, P.D.; Hins, A.G.; Park, J.Y.; Shack, W.J.

    1992-03-01T23:59:59.000Z

    Fatigue and stress corrosion cracking (SCC) for low-alloy steel used in piping and in steam generator and reactor pressure vessels have been investigated. Fatigue data were obtained on medium-sulfur-content A533-Gr B and A106-Gr B steels in high-purity (HP) deoxygenated water, in simulated pressurized water reactor water, and in air. Analytical studies focused on the behavior of carbon steels in boiling water reactor (BWR) environments. Crack-growth rates of composite fracture-mechanics specimens of A533-Gr B/Inconel-182/Inconel-600 (plated with nickel) and homogeneous specimens of A533-Gr B steel were determined under small-amplitude cyclic loading in HP water with {approx}300 pbb dissolved oxygen. Radiation-induced segregation and irradiation-assisted SCC of Type 304 SS after accumulation of relatively high fluence also have been investigated. Microchemical and microstructural changes in HP and commercial-purity Type 304 SS specimens from control-blade absorber tubes used in two operating BWRs were studied by Auger electron spectroscopy and scanning electron microscopy, and slow-strain-rate tensile tests were conducted on tubular specimens in air and in simulated BWR water at 289{degrees}C.

  13. Residual stresses and stress corrosion cracking in pipe fittings

    SciTech Connect (OSTI)

    Parrington, R.J.; Scott, J.J.; Torres, F.

    1994-06-01T23:59:59.000Z

    Residual stresses can play a key role in the SCC performance of susceptible materials in PWR primary water applications. Residual stresses are stresses stored within the metal that develop during deformation and persist in the absence of external forces or temperature gradients. Sources of residual stresses in pipe fittings include fabrication processes, installation and welding. There are a number of methods to characterize the magnitude and orientation of residual stresses. These include numerical analysis, chemical cracking tests, and measurement (e.g., X-ray diffraction, neutron diffraction, strain gage/hole drilling, strain gage/trepanning, strain gage/section and layer removal, and acoustics). This paper presents 400 C steam SCC test results demonstrating that residual stresses in as-fabricated Alloy 600 pipe fittings are sufficient to induce SCC. Residual stresses present in as-fabricated pipe fittings are characterized by chemical cracking tests (stainless steel fittings tested in boiling magnesium chloride solution) and by the sectioning and layer removal (SLR) technique.

  14. Catalytic cracking of a Gippsland reduced crude on zeolite catalysts

    SciTech Connect (OSTI)

    Guerzoni, F.N.; Abbot, J. (Univ. of Tasmania (Australia))

    1994-06-01T23:59:59.000Z

    Cracking reactions of a Gippsland reduced crude have been investigated at 520[degrees]C over HY and HZSM-5. Gasolines with similar characteristics can be obtained on both zeolites, although the mechanistic routes to these products are quite distinct. Changes in aromatic product selectivities are consistent with the zeolite pore geometries. Minor quantities of aromatics are formed via hydrogen transfer processes involving product olefins and naphthenes over the faujasite and the cyclization (and to a lesser extent oligomerization) of olefinic species on the pentasil. Dehydrogenation of naphthenic species in the feedstock is also important for aromatic formation. While paraffins are formed via hydrogen transfer processes together with cracking and isomerization of feed paraffins on HY, only the latter route can explain formation of saturated species on HZSM-5. The removal of linear paraffins from the GRC was traced as a function of conversion on HY. It was found that the relative reactivity of the linear paraffins increased monotonically with paraffin chain length. 43 refs., 11 figs., 8 tabs.

  15. Erasure of Time Delay Signatures in the Output of an Optoelectronic Feedback Laser with Modulated Delays and Chaos Synchronization

    E-Print Network [OSTI]

    E. M. Shahverdiev; K. A. Shore

    2009-06-17T23:59:59.000Z

    By studying the autocorrelation function of the optoelectronic feedback semiconductor laser output we establish that the signatures of time delays can be erased in systems incorporating modulated feedback time delays. This property is of importance for the suitability of such laser systems for secure chaos-based communication systems. We also make the first report on chaos synchronization in both unidirectionally and bidirectionally coupled multiple time delay chaotic semiconductor lasers with modulated optoelectronic feedbacks.

  16. Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks: Shrinkage-Reducing Admixtures, Internal Curing, and Cracking Performance

    E-Print Network [OSTI]

    Pendergrass, Ben Andrew

    2014-05-31T23:59:59.000Z

    ABSTRACT The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks is described based on laboratory tests of mixtures containing shrinkage-reducing admixtures and mineral admixtures in conjunction...

  17. Dynamical behaviours in time-delay systems with delayed feedback and digitized coupling

    E-Print Network [OSTI]

    Chiranjit Mitra; G. Ambika; Soumitro Banerjee

    2014-11-05T23:59:59.000Z

    We consider a network of delay dynamical systems connected in a ring via unidirectional positive feedback with constant delay in coupling. For the specific case of Mackey-Glass systems on the ring topology, we capture the phenomena of amplitude death, isochronous synchronization and phase-flip bifurcation as the relevant parameters are tuned. Using linear stability analysis and master stability function approach, we predict the region of amplitude death and synchronized states respectively in the parameter space and study the nature of transitions between the different states. For a large number of systems in the same dynamical configuration, we observe splay states, mixed splay states and phase locked clusters. We extend the study to the case of digitized coupling and observe that these emergent states still persist. However, the sampling and quantization reduce the regions of amplitude death and induce phase-flip bifurcation.

  18. Pattern of Thermal Fluctuations in a Recovery Boiler Floor

    SciTech Connect (OSTI)

    Abdullah, Z.; Gorog, J.P.; Keiser, J.R.; Meyers, L.E.; Swindeman, R.W.

    1999-04-25T23:59:59.000Z

    The floor of a black liquor recovey boiler at a mill in central Canada has experienced cracking and delamination of the composite tubing near the spout wall and deformation of the floor panels that is most severe in the vicinity of the spout wall. One possible explanation for the observed damage is impacts of salt cake falling from the convective section onto the floor. In order to determine if such impacts do occur, strain gauges and thermocouples were installed on the boiler floor in areas where cracking and deformation were most frequent. The data obtained from these instruments indicate that brief, sudden temperature fluctuations do occur, and changes in the strain experienced by the affected tube occur simultaneously. These fluctuations appear to occur less often along the spout wall and more frequently with increasing distance from the wall. The frequency of these temperature fluctuations is insufficient for thermal fatigue to be the sole cause of the cracking observed on the tubes, but the data are consistent with what might be expected from pieces of falling salt cake.

  19. Pattern of thermal fluctuations in a recovery boiler floor

    SciTech Connect (OSTI)

    Keiser, J.R.; Meyers, L.E.; Swindeman, R.W.; Gorog, J.P.; Abdullah, Z.

    1999-07-01T23:59:59.000Z

    The floor of a black liquor recovery boiler at a mill in central Canada has experienced cracking and delamination of the composite tubing near the spout wall and deformation of the floor panels that is most severe in the vicinity of the spout wail. One possible explanation for the observed damage is impacts of salt cake falling from the convective section onto the floor. In order to determine if such impacts do occur, strain gauges and thermocouples were installed on the boiler floor in areas where cracking and deformation were most frequent. The data obtained from these instruments indicate that brief, sudden temperature fluctuations do occur, and changes in the strain experienced by-the affected tube occur simultaneously. These fluctuations appear to occur less often along the spout wall and more frequently with increasing distance from the wall. The frequency of these temperature fluctuations is insufficient for thermal fatigue to be the sole cause of the cracking observed on the tubes, but the data are consistent with what might be expected from pieces of falling salt cake.

  20. THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice*

    E-Print Network [OSTI]

    THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice* ABSTRACT This paper briefly reviews progres~in the elastic plastic analysisof crack extension. Analytical results for plane strain and plane stress deformation fields are noted, and elastic-plastic fracture instability as well as transitional

  1. Thermo-optical modulation for improved ultrasonic fatigue crack detection in Ti6Al4V

    E-Print Network [OSTI]

    Nagy, Peter B.

    scatterers, such as surface grooves, corrosion pits, coarse grains, etc. that might hide the fatigue crack to grow at unexpectedly high growth rates well below the large-crack threshold in aluminum, aluminum­lithium) and secondary irregulari- ties (e.g. uneven machining, mechanical wear, corrosion, etc.). Second

  2. Interaction between corrosion crack width and steel loss in RC beams corroded under load

    SciTech Connect (OSTI)

    Malumbela, Goitseone, E-mail: malumbela@mopipi.ub.b [Dpt. of Civil Eng., Univ. of Cape Town, Private Bag X3, Rondebosch, 7700 (South Africa); Alexander, Mark; Moyo, Pilate [Dpt. of Civil Eng., Univ. of Cape Town, Private Bag X3, Rondebosch, 7700 (South Africa)

    2010-09-15T23:59:59.000Z

    This paper presents results and discussions on an experimental study conducted to relate the rate of widening of corrosion cracks with the pattern of corrosion cracks as well as the level of steel corrosion for RC beams (153 x 254 x 3000 mm) that were corroded whilst subjected to varying levels of sustained loads. Steel corrosion was limited to the tensile reinforcement and to a length of 700 mm at the centre of the beams. The rate of widening of corrosion cracks as well as strains on uncracked faces of RC beams was constantly monitored during the corrosion process, along the corrosion region and along other potential cracking faces of beams using a demec gauge. The distribution of the gravimetric mass loss of steel along the corrosion region was measured at the end of the corrosion process. The results obtained showed that: the rate of widening of each corrosion crack is dependent on the overall pattern of the cracks whilst the rate of corrosion is independent of the pattern of corrosion cracks. A mass loss of steel of 1% was found to induce a corrosion crack width of about 0.04 mm.

  3. Ultrasonic ply-by-ply detection of matrix cracks in laminated composites

    E-Print Network [OSTI]

    Ganpatye, Atul Shridatta

    2005-02-17T23:59:59.000Z

    on the internal damage state of the composite tank wall. Damage in the form of matrix cracks in the composite material of the tank is responsible for the through-the-thickness permeation of LH2. In this context, the detection of matrix cracks takes...

  4. Effect of Blast Design on Crack Response C.H. Dowding

    E-Print Network [OSTI]

    Effect of Blast Design on Crack Response C.H. Dowding Professor of Civil & Environmental to assess the effect of changes in blast design on the house response. Velocity response was measured some 11 velocity transducers and 3 crack sensors measured excitation and response for each blast

  5. Statistical fracture modeling: crack path and fracture criteria with application to homogeneous and

    E-Print Network [OSTI]

    Ritchie, Robert

    Statistical fracture modeling: crack path and fracture criteria with application to homogeneous; accepted 23 January 2002 Abstract Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows

  6. Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D

    E-Print Network [OSTI]

    Zhou, Wei

    Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D W. Zhou*, T. Z. Long and C. K ductility, and the HAZ was found to be the `weakest link'. Keywords: Magnesium alloy, AZ91D, TIG welding, Hot cracking, Liquation, Fracture Introduction Magnesium alloys have high strength/weight ratio

  7. Brittle fracture in a periodic structure with internal potential energy. Spontaneous crack propagation

    E-Print Network [OSTI]

    Mark Ayzenberg-Stepanenko; Gennady Mishuris; Leonid Slepyan

    2014-02-12T23:59:59.000Z

    Spontaneous brittle fracture is studied based on the recently introduced model (Mishuris and Slepyan, Brittle fracture in a periodic structure with internal potential energy. Proc. Roy. Soc. A, in press). A periodic structure is considered, where only the prospective crack-path layer is specified as a discrete set of alternating initially stretched and compressed bonds. A bridged crack destroying initially stretched bonds may propagate under a certain level of the internal energy without external sources. The general analytical solution with the crack speed $-$ energy relation is presented in terms of the crack-related dynamic Green's function. For the anisotropic two-line chain and lattice considered earlier in quasi-statics, the dynamic problem is examined in detail. The crack speed is found to grow unboundedly as the energy approaches its upper limit. It is revealed that the spontaneous fracture can occur in the form of a pure bridged, partially bridged or fully open crack depending on the internal energy level. Generally, the steady-state mode of the crack propagation is found to be realised, whereas an irregular growth, clustering and the crack speed oscillations are detected in a vicinity of the lower bound of the energy.

  8. DEVELOPMENT OF NONLINEAR TIME REVERSED ACOUSTICS (NLTRA) FOR APPLICATIONS TO CRACK DETECTION IN SOLIDS

    E-Print Network [OSTI]

    of Nondestructive Evaluation (NDE) exhibit extremely high sensitivity to the presence of cracks. Time Reverse stones and long-distance communication in the ocean. The Nondestructive Evaluation (NDE) applications,4] and detection of cracks in a thin air-filled hollow cylinder [5]. A review of TRA applications to NDE is given

  9. ccsd-00095604,version1-18Sep2006 Understanding crack versus cavitation in pressure-sensitive

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ccsd-00095604,version1-18Sep2006 Understanding crack versus cavitation in pressure show that in addition to cavitation, interfacial cracks are encountered in a probe-tack traction test mechanisms in usual adhesives. The most common one is cavitation, as evidenced by the first tests

  10. Autonomous Crack Displacement Monitoring of a Residence Near a Quarry David E. Kosnik, Northwestern University

    E-Print Network [OSTI]

    Autonomous Crack Displacement Monitoring of a Residence Near a Quarry David E. Kosnik, Northwestern remote mon- itoring of cracks in interior and exterior walls of a residence near a limestone quarry for construction and raw materials. For instance, neighbors of road aggregate quarries often perceive

  11. Autonomous Remote Crack Displacement Monitoring of a Residence Near a Limestone

    E-Print Network [OSTI]

    Autonomous Remote Crack Displacement Monitoring of a Residence Near a Limestone Quarry, Naples a limestone quarry. The object is to quantitatively compare crack re- sponse to blast-induced ground motion for construction and raw materials. For instance, neighbors of road aggregate quarries often perceive

  12. Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams

    SciTech Connect (OSTI)

    Khan, Inamullah; François, Raoul [Université de Toulouse, UPS, INSA, LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, Avenue de Rangueil, F-31077 Toulouse (France)] [Université de Toulouse, UPS, INSA, LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, Avenue de Rangueil, F-31077 Toulouse (France); Castel, Arnaud [Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW (Australia)] [Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW (Australia)

    2014-02-15T23:59:59.000Z

    This paper studies the evolution of reinforcement corrosion in comparison to corrosion crack width in a highly corroded reinforced concrete beam. Cracking and corrosion maps of the beam were drawn and steel reinforcement was recovered from the beam to observe the corrosion pattern and to measure the loss of mass of steel reinforcement. Maximum steel cross-section loss of the main reinforcement and average steel cross-section loss between stirrups were plotted against the crack width. The experimental results were compared with existing models proposed by Rodriguez et al., Vidal et al. and Zhang et al. Time prediction models for a given opening threshold are also compared to experimental results. Steel cross-section loss for stirrups was also measured and was plotted against the crack width. It was observed that steel cross-section loss in the stirrups had no relationship with the crack width of longitudinal corrosion cracks. -- Highlights: •Relationship between crack and corrosion of reinforcement was investigated. •Corrosion results of natural process and then corresponds to in-situ conditions. •Comparison with time predicting model is provided. •Prediction of load-bearing capacity from crack pattern was studied.

  13. Analysis of the tube-sheet cracking in slurry oil steam , L.J. Qiao a,

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Analysis of the tube-sheet cracking in slurry oil steam generators L.K. Zhu a , L.J. Qiao a, , X and increased costs. In this study, the mechanisms of the tube- sheet cracking in slurry oil steam generators steam generator is a kind of shell and tube heat exchanger extensively used in the oil refinement

  14. Efficient solution of multiple cracks in great number using eigen COD boundary integral equations with iteration procedure

    E-Print Network [OSTI]

    Liu, Yijun

    as the fibre-reinforced brittle materials after certain extent of tensile damage. The prediction of crack in an infinite domain under fictitious traction acting on the crack surface. With the concept of eigen COD

  15. Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within the oxide layer

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within with stress-induced surface oxide thicken- ing and moisture-assisted subcritical cracking in the amor- phous

  16. Reflective Cracking Study: First-level Report on HVS Testing on Section 586RF - 45 mm MB15-GOverlay

    E-Print Network [OSTI]

    Jones, David; Wu, R; Harvey, John T

    2008-01-01T23:59:59.000Z

    of the asphalt concrete layer. Testing was stopped when thetesting being performed to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete.concrete. It describes the results of the fifth HVS reflective cracking testing

  17. Reflective Cracking Study: First-Level Report on HVS Testing on Section 589RF - 45 mm MB4-G Overlay

    E-Print Network [OSTI]

    Jones, David; Harvey, John T; Wu, R; Lea, J.

    2008-01-01T23:59:59.000Z

    of the asphalt concrete layer. Testing was stopped when thetesting being performed to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete.concrete. It describes the results of the second HVS reflective cracking testing

  18. Fatigue crack propagation in a quasi one-dimensional elasto-plastic model

    E-Print Network [OSTI]

    Tomás M. Guozden; Eduardo A. Jagla

    2012-06-27T23:59:59.000Z

    Fatigue crack advance induced by the application of cyclic quasistatic loads is investigated both numerically and analytically using a lattice spring model. The system has a quasi-one-dimensional geometry, and consists in two symmetrical chains that are pulled apart, thus breaking springs which connect them, and producing the advance of a crack. Quasistatic crack advance occurs as a consequence of the plasticity included in the springs which form the chains, and that implies a history dependent stress-strain curve for each spring. The continuous limit of the model allows a detailed analytical treatment that gives physical insight of the propagation mechanism. This simple model captures key features that cause well known phenomenology in fatigue crack propagation, in particular a Paris-like law of crack advance under cyclic loading, and the overload retardation effect.

  19. Characterization of elevated temperature crack growth in Hastelloy-X using integral parameters

    SciTech Connect (OSTI)

    Kim, K.S. [Pohang Univ. of Science and Technology (Korea, Republic of). Dept. of Mechanical Engineering; Van Stone, R.H. [General Electric Aircraft Engines, Cincinnati, OH (United States)

    1995-07-01T23:59:59.000Z

    Linear elastic fracture mechanics approaches are not suitable for prediction of fatigue crack growth in the nonlinear regime at elevated temperatures. The objective of this paper is to investigate the ability of the integral parameters by Blackburn (J*), by Kishimoto et al. ({cflx J}), and by Atluri et al. ({Delta}Tp*, {Delta}Tp) to correlate crack growth data of Hastelloy-X at elevated temperatures under nominally elastic and nominally plastic loading. Crack growth is analyzed using a finite element method, and the integral parameters are computed from the results of analysis. The experimental crack growth rates are correlated with these parameters. It is found that J*, {cflx J}, and {Delta}Tp* can correlate crack growth data within an acceptable accuracy.

  20. Vickers microindentation toughness of a sintered SiC in the median-crack regime

    SciTech Connect (OSTI)

    Ghosh, Asish; Kobayashi, A.S. (Washington Univ., Seattle, WA (United States). Coll. of Engineering); Li, Zhuang (Argonne National Lab., IL (United States)); Henager, C.H. Jr. (Pacific Northwest Lab., Richland, WA (United States)); Bradt, R.C. (Nevada Univ., Reno, NV (United States). Mackay School of Mines)

    1991-01-01T23:59:59.000Z

    The Vickers microindentation method for the determination of the fracture toughness of ceramics was investigated in the median crack regime for a sintered alpha SiC. The results are compared with fracture toughness measurements by conventional fracture mechanics technique and also with the reported indentation toughness for the low-load Palmqvist crack regime. Indentation toughnesses in the median crack regime vary widely depending on the choice of the specific equation which is applied. The indentation toughnesses are also load (crack length) dependent. A decreasing R-curve trend results, in contradiction to the flat R-curve that has been observed with conventional fracture mechanics techniques. It is concluded that the Vickers microindentation method is not a reliable technique for the determination of the fracture toughness of ceramics in the median crack regime.

  1. Robust Airline Schedule Planning: Minimizing Propagated Delay in ...

    E-Print Network [OSTI]

    2011-10-06T23:59:59.000Z

    highly brittle, performing poorly in practice as delays propagate rapidly throughout the network. The. Bureau of .... In contrast to airline recovery, where the objective is to achieve the best ..... weather conditions, air traffic flow management, passenger delays, equipment failure, and so on. ...... Airport Handling Manual. 2010.

  2. MCNP6 enhancements of delayed-particle production

    SciTech Connect (OSTI)

    McKinney, G. W. [Los Alamos National Laboratory, MS C921, P.O. Box 1663, Los Alamos, NM 87545 (United States)

    2012-07-01T23:59:59.000Z

    Over the last decade, there has been an increased interest in the production of delayed-particle signatures from neutron and photon interactions with matter. To address this interest, various radiation transport codes have developed a wide range of delayed-particle physics packages. With the recent merger of the Monte Carlo transport codes MCNP5 and MCNPX, MCNP6 inherited the comprehensive model-based delayed-particle production capabilities developed in MCNPX over the last few years. An integral part of this capability consists of the depletion code CINDER90 which was incorporated into MCNPX in 2004. During this last year, significant improvements have been made to the MCNP6 physics and algorithms associated with delayed-particle production, including the development of a delayed-beta capability, an algorithm enhancement for the delayed-neutron treatment, and a database enhancement for delayed-gamma emission. The delayed-beta feature represents an important component in modeling background signals produced by active interrogation sources. Combined, these improvements provide MCNP6 with a flexible state-of-the-art physics package for generating high-fidelity signatures from fission and activation. This paper provides details of these enhancements and presents results for a variety of fission and activation examples. (authors)

  3. M/M/1 Queueing System with Delayed Controlled Vacation

    E-Print Network [OSTI]

    Zhao, Yiqiang Q.

    M/M/1 Queueing System with Delayed Controlled Vacation Yonglu Deng , Zhongshan University W. John systems using a time division multiple access (TDMA) scheme (Frey and Takahashi, [7]). Researchers have that of a server's cold switch-on. The case of delayed vacation has also very recently been studied by Frey

  4. Utility Maximization for Delay Constrained QoS in Wireless

    E-Print Network [OSTI]

    Utility Maximization for Delay Constrained QoS in Wireless I-Hong Hou CSL and Department of CS of utility maxi- mization for clients with delay based QoS requirements in wireless networks. We adopt that the utility of a client is a function of the timely throughput it obtains. We treat the timely throughput

  5. MISO Broadcast Channel with Delayed and Evolving CSIT

    E-Print Network [OSTI]

    Gesbert, David

    MISO Broadcast Channel with Delayed and Evolving CSIT Jinyuan Chen and Petros Elia Mobile--The work considers the two-user MISO broadcast channel with a gradual and delayed accumulation of channel-input single-output broadcast channel (MISO BC) with an M-transmit antenna (M 2) transmitter communicating

  6. Convex Delay Models for Transistor Sizing Mahesh Ketkar

    E-Print Network [OSTI]

    Sapatnekar, Sachin

    for developing accurate con- vex delay models to be used for transistor sizing. A new rich class of convex]: minimize Area or Power subject to Delay Tspec: (1) There have been many significant attempts to solve. in the development of closed form models for inverters and then mapping other gates to an equivalent inverter [5, 6

  7. Regenerative memory in time-delayed neuromorphic photonic systems

    E-Print Network [OSTI]

    Romeira, B; Figueiredo, José M L; Barland, S; Javaloyes, J

    2015-01-01T23:59:59.000Z

    We investigate a regenerative memory based upon a time-delayed neuromorphic photonic oscillator and discuss the link with temporal localized structures. Our experimental implementation is based upon a optoelectronic system composed of a nanoscale nonlinear resonant tunneling diode coupled to a laser that we link to the paradigm of neuronal activity, the FitzHugh-Nagumo model with delayed feedback.

  8. Review of industry efforts to manage pressurized water reactor feedwater nozzle, piping, and feedring cracking and wall thinning

    SciTech Connect (OSTI)

    Shah, V.N.; Ware, A.G.; Porter, A.M.

    1997-03-01T23:59:59.000Z

    This report presents a review of nuclear industry efforts to manage thermal fatigue, flow-accelerated corrosion, and water hammer damage to pressurized water reactor (PWR) feedwater nozzles, piping, and feedrings. The review includes an evaluation of design modifications, operating procedure changes, augmented inspection and monitoring programs, and mitigation, repair and replacement activities. Four actions were taken: (a) review of field experience to identify trends of operating events, (b) review of technical literature, (c) visits to PWR plants and a PWR vendor, and (d) solicitation of information from 8 other countries. Assessment of field experience is that licensees have apparently taken sufficient action to minimize feedwater nozzle cracking caused by thermal fatigue and wall thinning of J-tubes and feedwater piping. Specific industry actions to minimize the wall-thinning in feedrings and thermal sleeves were not found, but visual inspection and necessary repairs are being performed. Assessment of field experience indicates that licensees have taken sufficient action to minimize steam generator water hammer in both top-feed and preheat steam generators. Industry efforts to minimize multiple check valve failures that have allowed backflow of steam from a steam generator and have played a major role in several steam generator water hammer events were not evaluated. A major finding of this review is that analysis, inspection, monitoring, mitigation, and replacement techniques have been developed for managing thermal fatigue and flow-accelerated corrosion damage to feedwater nozzles, piping, and feedrings. Adequate training and appropriate applications of these techniques would ensure effective management of this damage.

  9. Delays associated with elementary processes in nuclear reaction simulations

    SciTech Connect (OSTI)

    Danielewicz, P.; Pratt, S. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)] [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); [Grand Accelerateur National dIons Lourds (GANIL), BP 5027, F-14021 Caen Cedex (France)

    1996-01-01T23:59:59.000Z

    Scatterings, particularly those involving resonances, and other elementary processes do not happen instantaneously. In the context of semiclassical nuclear reaction simulations, we consider delays associated with an interaction for incident quantum wave packets. As a consequence, we express delays associated with elementary processes in terms of elements of the scattering matrix and phase shifts for elastic scattering. We show that, within the second order in density, the simulation must account for delays in scattering consistently with the mean field in order to properly model thermodynamic properties such as pressure and free-energy density. Delays associated with nucleon-nucleon and pion-nucleon scattering in free space are analyzed with their nontrivial energy dependence. Finally, an example of {ital s}-channel scattering of massless partons is studied, and scattering schemes in nuclear reaction simulations are investigated in the context of scattering delays. {copyright} {ital 1996 The American Physical Society.}

  10. Holographic thermalization patterns

    E-Print Network [OSTI]

    Stefan Stricker

    2014-03-11T23:59:59.000Z

    We investigate the behaviour of various correlators in N=4 super Yang Mills theory, taking finite coupling corrections into account. In the thermal limit we investigate the flow of the quasinormal modes as a function of the 't Hooft coupling. Then by using a specific model of holographic thermalization we investigate the deviation of the spectral densities from their thermal limit in an out-of-equilibrium situation. The main focus lies on the thermalization pattern with which the various plasma constituents of different energies approach their final thermal distribution as the coupling constant decreases from the infinite coupling limit. All results point towards the weakening of the usual top down thermalization pattern.

  11. HEATS: Thermal Energy Storage

    SciTech Connect (OSTI)

    None

    2012-01-01T23:59:59.000Z

    HEATS Project: The 15 projects that make up ARPA-E’s HEATS program, short for “High Energy Advanced Thermal Storage,” seek to develop revolutionary, cost-effective ways to store thermal energy. HEATS focuses on 3 specific areas: 1) developing high-temperature solar thermal energy storage capable of cost-effectively delivering electricity around the clock and thermal energy storage for nuclear power plants capable of cost-effectively meeting peak demand, 2) creating synthetic fuel efficiently from sunlight by converting sunlight into heat, and 3) using thermal energy storage to improve the driving range of electric vehicles (EVs) and also enable thermal management of internal combustion engine vehicles.

  12. A continuing investigation into the stress field around two parallet-edge cracks in a finite body

    E-Print Network [OSTI]

    Gilman, Justin Patrick

    2005-02-17T23:59:59.000Z

    ,7 ........................................................................................... 5 2.1 Two Parallel Edge Cracks in a Four Point Bending Member.............................. 7 2.2 Westergaard Stress Functions and Resulting Stress Intensity Factors for a Crack with Applied Tractions Along Its Faces... .................................................................... 31 4.2 Mesh Created for Numerical Model (Zoomed in on Crack Interaction Region) ............................................................................................. 32 5.1 Open Mode Stress Intensity Factor Percent...

  13. EFFECT OF STRESS GRADIENT AT THE VICINITY OF A CRACK TIP ON IONIC DIFFUSION IN SILICATE GLASSES: AN AFM STUDY.

    E-Print Network [OSTI]

    Demouchy, Sylvie

    1 EFFECT OF STRESS GRADIENT AT THE VICINITY OF A CRACK TIP ON IONIC DIFFUSION IN SILICATE GLASSES.marliere@univ-montp2.fr ABSTRACT The slow advance of a crack in sodo-silicate glasses was studied at nanometer scale-micrometric vicinity of the tip of a crack running in silicate glass with mobile ions (as sodium cations) and check

  14. Status of six-group delayed neutron data and relationships between delayed neutron parameters from the macroscopic and microscopic approaches

    SciTech Connect (OSTI)

    Parish, T.A.; Charlton, W.S. [Texas A and M Univ., College Station, TX (United States). Nuclear Engineering Dept.; Shinohara, N.; Andoh, M. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan); Brady, M.C. [Duke Engineering and Services, Inc., Charlotte, NC (United States); Raman, S. [Oak Ridge National Lab., TN (United States)

    1999-02-01T23:59:59.000Z

    Work performed in part for an American Nuclear Society Standards Committee Subgroup (ANS 19.9) to assess the status of delayed neutron data is summarized. Recent measurements of delayed neutron emission conducted at Texas A and M University are also described. During the last 10 yr, there have been advances in nuclear data libraries (e.g., improved fission product yields) that make it possible to quantitatively predict delayed neutron emission from basic data. The six-group delayed neutron data available in the literature from both macroscopic level experiments and microscopic level calculations for several actinide isotopes are compared. Results are also presented from recent experimental measurements of delayed neutron emission and delineates some of the relationships between these measurements and microscopic level predictions. For example, from the experimental measurements, Keepin`s delayed neutron group 1 is shown to correspond mainly to a single isotope. {sup 87}Br, as expected from microscopic level theory, and Keepin`s group 2 is shown to correspond to primarily two separate isotopes. {sup 137}I and {sup 88}Br. In the future, it may be useful to use properties of specific isotopes to replace Keepin`s delayed neutron groups 1, 2, 3, and 4 for prescribing delayed neutron data for actinides.

  15. Monitoring Thermal Fatigue Damage In Nuclear Power Plant Materials Using Acoustic Emission

    SciTech Connect (OSTI)

    Meyer, Ryan M.; Ramuhalli, Pradeep; Watson, Bruce E.; Pitman, Stan G.; Roosendaal, Timothy J.; Bond, Leonard J.

    2012-04-26T23:59:59.000Z

    Proactive aging management of nuclear power plant passive components requires technologies to enable monitoring and accurate quantification of material condition at early stages of degradation (i.e., pre-macrocrack). Acoustic emission (AE) is well-suited to continuous monitoring of component degradation and is proposed as a method to monitor degradation during accelerated thermal fatigue tests. A key consideration is the ability to separate degradation responses from external sources such as water spray induced during thermal fatigue testing. Water spray provides a significant background of acoustic signals, which can overwhelm AE signals caused by degradation. Analysis of AE signal frequency and energy is proposed in this work as a means for separating degradation signals from background sources. Encouraging results were obtained by applying both frequency and energy filters to preliminary data. The analysis of signals filtered using frequency and energy provides signatures exhibiting several characteristics that are consistent with degradation accumulation in materials. Future work is planned to enable verification of the efficacy of AE for thermal fatigue crack initiation detection. While the emphasis has been placed on the use of AE for crack initiation detection during accelerated aging tests, this work also has implications with respect to the use of AE as a primary tool for early degradation monitoring in nuclear power plant materials. The development of NDE tools for characterization of aging in materials can also benefit from the use of a technology such as AE which can continuously monitor and detect crack initiation during accelerated aging tests.

  16. Non-thermal Plasma Chemistry Non-thermal Thermal

    E-Print Network [OSTI]

    Greifswald, Ernst-Moritz-Arndt-Universität

    -thermal Plasma Chemical Flow Reactor #12;Werner von Siemens ,, ... construction of an apparatus generation (1857) pollution control volatile organic components, NOx reforming, ... radiation sources excimer;Leuchtstoffröhre Plasma-Bildschirm Energiesparlampe #12;electrical engineering light sources textile industry

  17. Ashland Oil Inc. has new heavy oil cracking technology

    SciTech Connect (OSTI)

    Not Available

    1980-04-21T23:59:59.000Z

    Ashland's new ''Reduced Crude Conversion'' is a fluid catalytic cracking process that permits more efficient use of the bottoms of the crude barrel, including the production of a given amount of gasoline from 20% less crude. Gasoline yields go from 49.8% for Arabian light crudes to 56.9% for Murban crudes. The new process, details of which have not been revealed, operates at ''high'' temperatures and about 1 atm; requires no feed hydrogen (and therefore, according to Ashland, compares favorably with hydrocracking); is not inhibited by catalyst poisons such as nickel and vanadium, even though these metals might adhere to the proprietary catalyst; and probably uses a zeolite catalyst. Ashland is planning a $70 million, 40,000 bbl/day unit which is scheduled to go on stream in 1982 at its Catlettsburg, Ky., refinery.

  18. Syneresis and delayed detachment in agar plates

    E-Print Network [OSTI]

    Thibaut Divoux; Bosi Mao; Patrick Snabre

    2014-10-30T23:59:59.000Z

    Biogels made of crosslinked polymers such as proteins or polysaccharides behave as porous soft solids and store large amount of solvent. These gels undergo spontaneous aging, called syneresis that consists in the shrinkage of the gel matrix and the progressive expulsion of the solvent, which eventually leads to the gel detachment from its container. Here we report on the syneresis phenomena in agar plates that consist in Petri dishes filled with a gel mainly composed of agar. Direct observations and speckle pattern correlation analyses allow us to rationalize the delayed detachment of the gel from the sidewall of the Petri dish. The detachment time $t^*$ is mainly controlled by the gel minimum thickness $e_{min}$ along the periphery of the plate: $t^*$ increases as a robust function of $e_{min}$ that neither depends on the age of the gel nor on any previous mass loss. Time-resolved correlation spectroscopy reveals that the speckle decorrelation rate increases a few hours before $t^*$ and that the gel detachment can be anticipated. This work provides quantitative observables to predict the shelf life of agar plates and highlights the key role of the competition between the syneresis and the gel adhesion to the wall in the detachment process.

  19. Thermal contact resistance

    E-Print Network [OSTI]

    Mikic, B. B.

    1966-01-01T23:59:59.000Z

    This work deals with phenomena of thermal resistance for metallic surfaces in contact. The main concern of the work is to develop reliable and practical methods for prediction of the thermal contact resistance for various ...

  20. Thermal-mechanical fatigue behavior of nickel-base superalloys. Final Report

    SciTech Connect (OSTI)

    Pelloux, R.M.; Marchand, N.

    1986-03-01T23:59:59.000Z

    The main achievements of a 36-month research program are presented. The main objective was to gain more insight into the problem of crack growth under thermal mechanical fatigue (TMF) conditions. This program was conducted at M.I.T. for the period of September 1982 to September 1985. The program was arranged into five technical tasks. Under Task I, the literature of TMF data was reviewed. The goal was to identify the crack propagation conditions in aircraft engines (hot section) and to assess the validity of conventional fracture mechanics parameters to address TMF crack growth. The second task defined the test facilities, test specimen and the testing conditions needed to establish the effectiveness of data correlation parameters identified in Task I. Three materials (Inconel X-750, Hastelloy-X, and B-1900) were chosen for the program. Task II was accomplished in collaboration with Pratt and Whitney Aircraft engineers. Under Task III, a computerized testing system to measure the TMF behavior (LCF and CG behaviors) of various alloys systems was built. The software used to run isothermal and TMF tests was also developed. Built around a conventional servohydraulic machine, the system is capable of push-pull tests under stress or strain and temperature controlled conditions in the temperature range of 25C to 1050C. A crack propagation test program was defined and conducted under Task IV. The test variables included strain range, strain rate (frequency) and temperature. Task V correlated and generalized the Task IV data for isothermal and variable temperature conditions so that several crack propagation parameters could be compared and evaluated. The structural damage (mode of cracking and dislocation substructure) under TMF cycling was identified and contrasted with the isothermal damage to achieve a sound fundamental mechanistic understanding of TMF.

  1. Thermal Processes | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    Hydrogen Production Current Technology Thermal Processes Thermal Processes Some thermal processes use the energy in various resources, such as natural gas, coal, or biomass,...

  2. Evaluation and application of delayed neutron precursor data

    SciTech Connect (OSTI)

    Brady, M.C.

    1989-04-01T23:59:59.000Z

    Up to 1300 nuclides are yielded in fission. Of these, 271 have been identified as precursors for delayed neutron emission. An extensive reference library of delayed neutron data has been compiled which contains fission yields and branchings, delay neutron emission probabilities and spectra for each of these 271 precursor nuclides. The emphasis of the present work has been in improving the spectral data. Experimental spectra from laboratories in the United States, Germany, and Sweden have been incorporated in this evaluation. The experimental spectra have been augmented with model calculations such that the spectra included in the final library extend over the full theoretical energy range for delayed neutron emission. Models were also used to predict spectra for nuclides with no measured data. The data compiled in the precursor library have been used to calculate the aggregate behavior of delayed neutrons for the 43 fissioning systems having evaluated fission yields. Delayed neutron activities predicted using the explicit precursor data have also been approximated by three, six, nine and twelve time-groups using least squares techniques. The fitted six group data, being the more conventional representation, were also used to predict a consistent set of six-group spectra. Comparisons with the University of Lowell's recently published measurements of /sup 235/U delay interval spectra were also made. Beta-effective calculations for a simple Godiva system were performed and were compared to the experimental value.

  3. Development of a statistically based access delay timeline methodology.

    SciTech Connect (OSTI)

    Rivera, W. Gary; Robinson, David Gerald; Wyss, Gregory Dane; Hendrickson, Stacey M. Langfitt

    2013-02-01T23:59:59.000Z

    The charter for adversarial delay is to hinder access to critical resources through the use of physical systems increasing an adversary's task time. The traditional method for characterizing access delay has been a simple model focused on accumulating times required to complete each task with little regard to uncertainty, complexity, or decreased efficiency associated with multiple sequential tasks or stress. The delay associated with any given barrier or path is further discounted to worst-case, and often unrealistic, times based on a high-level adversary, resulting in a highly conservative calculation of total delay. This leads to delay systems that require significant funding and personnel resources in order to defend against the assumed threat, which for many sites and applications becomes cost prohibitive. A new methodology has been developed that considers the uncertainties inherent in the problem to develop a realistic timeline distribution for a given adversary path. This new methodology incorporates advanced Bayesian statistical theory and methodologies, taking into account small sample size, expert judgment, human factors and threat uncertainty. The result is an algorithm that can calculate a probability distribution function of delay times directly related to system risk. Through further analysis, the access delay analyst or end user can use the results in making informed decisions while weighing benefits against risks, ultimately resulting in greater system effectiveness with lower cost.

  4. Delayed feedback control of fractional-order chaotic systems

    E-Print Network [OSTI]

    Aleksandar Gjurchinovski; Trifce Sandev; Viktor Urumov

    2011-07-06T23:59:59.000Z

    We study the possibility to stabilize unstable steady states and unstable periodic orbits in chaotic fractional-order dynamical systems by the time-delayed feedback method. By performing a linear stability analysis, we establish the parameter ranges for successful stabilization of unstable equilibria in the plane parametrizad by the feedback gain and the time delay. An insight into the control mechanism is gained by analyzing the characteristic equation of the controlled system, showing that the control scheme fails to control unstable equilibria having an odd number of positive real eigenvalues. We demonstrate that the method can also stabilize unstable periodic orbits for a suitable choice of the feedback gain, providing that the time delay is chosen to coincide with the period of the target orbit. In addition, it is shown numerically that delayed feedback control with a sinusoidally modulated time delay significantly enlarges the stability region of the steady states in comparison to the classical time-delayed feedback scheme with a constant delay.

  5. Thermal imaging measurement of lateral diffusivity and non-invasive material defect detection

    DOE Patents [OSTI]

    Sun, Jiangang (Westmont, IL); Deemer, Chris (Downers Grove, IL)

    2003-01-01T23:59:59.000Z

    A system and method for determining lateral thermal diffusivity of a material sample using a heat pulse; a sample oriented within an orthogonal coordinate system; an infrared camera; and a computer that has a digital frame grabber, and data acquisition and processing software. The mathematical model used within the data processing software is capable of determining the lateral thermal diffusivity of a sample of finite boundaries. The system and method may also be used as a nondestructive method for detecting and locating cracks within the material sample.

  6. Multiwavelength Thermal Emission

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Multiwavelength Astronomy NASA #12;Thermal Emission #12;Thermal Emission Non-thermal p-p collisions Optical IR Radio/ Microwave sources of emission massive stars, WHIM, Ly many dust, cool objects-ray ~GeV Gamma-ray ~TeV sources of emission AGN, clusters, SNR, binaries, stars AGN (obscured), shocks

  7. Thermal Performance Benchmarking (Presentation)

    SciTech Connect (OSTI)

    Moreno, G.

    2014-11-01T23:59:59.000Z

    This project will benchmark the thermal characteristics of automotive power electronics and electric motor thermal management systems. Recent vehicle systems will be benchmarked to establish baseline metrics, evaluate advantages and disadvantages of different thermal management systems, and identify areas of improvement to advance the state-of-the-art.

  8. Thermal neutron detection system

    DOE Patents [OSTI]

    Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

    2000-01-01T23:59:59.000Z

    According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

  9. Concrete cover cracking with reinforcement corrosion of RC beam during chloride-induced corrosion process

    SciTech Connect (OSTI)

    Zhang Ruijin, E-mail: rjzhang@mail.neu.edu.c [Modern Design and Analysis Research Institute, Northeastern University, Shenyang (China); Castel, Arnaud; Francois, Raoul [LMDC - Laboratoire Materiaux et Durabilite des Constructions, Universite de Toulouse, UPS, INSA, Toulouse (France)

    2010-03-15T23:59:59.000Z

    This paper deals with the evolution of the corrosion pattern based on two beams corroded by 14 years (beam B1CL1) and 23 years (beam B2CL1) of conservation in a chloride environment. The experimental results indicate that, at the cracking initiation stage and the first stage of cracking propagation, localized corrosion due to chloride ingress is the predominant corrosion pattern and pitting corrosion is the main factor that influences the cracking process. As corrosion cracking increases, general corrosion develops rapidly and gradually becomes predominant in the second stage of cracking propagation. A comparison between existing models and experimental results illustrates that, although Vidal et al.'s model can better predict the reinforcement corrosion of beam B1CL1 under localized corrosion, it cannot predict the corrosion of beam B2CL1 under general corrosion. Also, Rodriguez's model, derived from the general corrosion due to electrically accelerated corrosion experiments, cannot match natural chloride corrosion irrespective of whether corrosion is localized or general. Thus, for natural general corrosion in the second stage of cracking propagation, a new model based on the parameter of average steel cross-section loss is put forward to predict steel corrosion from corrosion cracking.

  10. Conditions under which cracks occur in modified 13% chromium steel in wet hydrogen sulfide environments

    SciTech Connect (OSTI)

    Hara, T.; Asahi, H.

    2000-05-01T23:59:59.000Z

    Occurrence of cracks in an API 13% Cr steel, modified 13% Cr steel, and duplex stainless steel were compared in various wet, mild hydrogen sulfide (H{sub 2}S) environments. The conditions under which cracks occurred in the modified 13% Cr steel in oil and gas production environments were made clear. No cracks occurred if pH > depassivation pH (pH{sub d}) and redox potential of sulfur (E{sub S(red/ax)}) < pitting potential (V{sub c}). Hydrogen embrittlement-type cracks occurred in pH > Ph{sub d} and E{sub S(red/ax)} > V{sub c}. The pH inside the pit decreased drastically and hydrogen embrittlement occurred. Cracks of the hydrogen embrittlement type occurred if pH < pH{sub d} and threshold hydrogen concentration under which cracks occur (H{sub th}) < hydrogen concentration in steel (H{sub 0}). No cracks occurred if pH < pH{sub d} and H{sub th} > H{sub 0}.

  11. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    SciTech Connect (OSTI)

    Krishnan, S.; Bhasin, V.; Mahajan, S.C. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01T23:59:59.000Z

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.

  12. Threshold velocity for environmentally-assisted cracking in low alloy steels

    SciTech Connect (OSTI)

    Wire, G.L.; Kandra, J.T.

    1997-04-01T23:59:59.000Z

    Environmentally Assisted Cracking (EAC) in low alloy steels is generally believed to be activated by dissolution of MnS inclusions at the crack tip in high temperature LWR environments. EAC is the increase of fatigue crack growth rate of up to 40 to 100 times the rate in air that occurs in high temperature LWR environments. A steady state theory developed by Combrade, suggested that EAC will initiate only above a critical crack velocity and cease below this same velocity. A range of about twenty in critical crack tip velocities was invoked by Combrade, et al., to describe data available at that time. This range was attributed to exposure of additional sulfides above and below the crack plane. However, direct measurements of exposed sulfide densities on cracked specimens were performed herein and the results rule out significant additional sulfide exposure as a plausible explanation. Alternatively, it is proposed herein that localized EAC starting at large sulfide clusters reduces the calculated threshold velocity from the value predicted for a uniform distribution of sulfides. Calculations are compared with experimental results where the threshold velocity has been measured, and the predicted wide range of threshold values for steels of similar sulfur content but varying sulfide morphology is observed. The threshold velocity decreases with the increasing maximum sulfide particle size, qualitatively consistent with the theory. The calculation provides a basis for a conservative minimum velocity threshold tied directly to the steel sulfur level, in cases where no details of sulfide distribution are known.

  13. Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management

    E-Print Network [OSTI]

    Bouchez, Marc; Visez, Nicolas; Herbinet, Olivier; Fournet, René; Marquaire, Paul-Marie

    2009-01-01T23:59:59.000Z

    The last years saw a renewal of interest for hypersonic research in general and regenerative cooling specifically, with a large increase of the number of dedicated facilities and technical studies. In order to quantify the heat transfer in the cooled structures and the composition of the cracked fuel entering the combustor, an accurate model of the thermal decomposition of the fuel is required. This model should be able to predict the fuel chemical composition and physical properties for a broad range of pressures, temperatures and cooling geometries. For this purpose, an experimental and modeling study of the thermal decomposition of generic molecules (long-chain or polycyclic alkanes) that could be good surrogates of real fuels, has been started at the DCPR laboratory located in Nancy (France). This successful effort leads to several versions of a complete kinetic model. These models do not assume any effect from the material that constitutes the cooling channel. A specific experimental study was performed ...

  14. Full-field characterization of thermal diffusivity in continuous- fiber ceramic composite materials and components

    SciTech Connect (OSTI)

    Steckenrider, J.S.; Ellingson, W.A. [Argonne National Lab., IL (United States); Rothermel, S.A. [South Dakota State Univ., Brookings, SD (United States)

    1995-05-01T23:59:59.000Z

    Continuous-fiber ceramic matrix composites (CFCCs) are currently being developed for various high-temperature applications, including use in advanced heat engines. Among the material classes of interest for such applications are silicon carbide (SiC)-fiber-reinforced SiC (SiC{sub (f)}/SiC), SiC-fiber-reinforced silicon nitride (SiC {sub (f)}/Si{sub 3}N{sub 4}), aluminum oxide (Al{sub 2}O{sub 3})-fiber-reinforced Al{sub 2}O{sub 3} (Al{sub 2}O{sub 3}{sub (f)}/Al{sub 2}O{sub 3}), and others. In such composites, the condition of the interfaces (between the fibers and matrix) are critical to the mechanical and thermal behavior of the component (as are conventional mechanical defects such as cracks, porosity, etc.). For example, oxidation of this interface (especially on carbon coated fibers) can seriously degrade both mechanical and thermal properties. Furthermore, thermal shock damage can degrade the matrix through extensive crack generation. A nondestructive evaluation method that could be used to assess interface condition, thermal shock damage, and to detect other ``defects`` would thus be very beneficial, especially if applicable to full-scale components. One method under development uses infrared thermal imaging to provide ``single-shot`` full-field assessment of the distribution of thermal properties in large components by measuring thermal diffusivity. By applying digital image filtering, interpolation, and least-squares-estimation techniques for noise reduction, we can achieve acquisition and analysis times of minutes or less with submillimeter spatial resolution. The system developed at Argonne has been used to examine the effects of thermal shock, oxidation treatment, density variations, and variations in oxidation resistant coatings in a full array of test specimens. Subscale CFCC components with nonplanar geometries have also been studied for manufacturing-induced variations in thermal properties.

  15. Crack growth rates of nickel alloy welds in a PWR environment.

    SciTech Connect (OSTI)

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.; Energy Technology

    2006-05-31T23:59:59.000Z

    In light water reactors (LWRs), vessel internal components made of nickel-base alloys are susceptible to environmentally assisted cracking. A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals. A program is being conducted at Argonne National Laboratory to evaluate the resistance of Ni alloys and their welds to environmentally assisted cracking in simulated LWR coolant environments. This report presents crack growth rate (CGR) results for Alloy 182 shielded-metal-arc weld metal in a simulated pressurized water reactor (PWR) environment at 320 C. Crack growth tests were conducted on 1-T compact tension specimens with different weld orientations from both double-J and deep-groove welds. The results indicate little or no environmental enhancement of fatigue CGRs of Alloy 182 weld metal in the PWR environment. The CGRs of Alloy 182 in the PWR environment are a factor of {approx}5 higher than those of Alloy 600 in air under the same loading conditions. The stress corrosion cracking for the Alloy 182 weld is close to the average behavior of Alloy 600 in the PWR environment. The weld orientation was found to have a profound effect on the magnitude of crack growth: cracking was found to propagate faster along the dendrites than across them. The existing CGR data for Ni-alloy weld metals have been compiled and evaluated to establish the effects of key material, loading, and environmental parameters on CGRs in PWR environments. The results from the present study are compared with the existing CGR data for Ni-alloy welds to determine the relative susceptibility of the specific Ni-alloy weld to environmentally enhanced cracking.

  16. Simulations of Failure via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels

    SciTech Connect (OSTI)

    Lu, Hongbing; Bukkapatnam, Satish; Harimkar, Sandip; Singh, Raman; Bardenhagen, Scott

    2014-01-09T23:59:59.000Z

    Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear fuels are critical to understand the burnup, and thus the fuel efficiency.

  17. Design of coupling for synchronization in time-delayed systems

    E-Print Network [OSTI]

    Dibakar Ghosh; Ioan Grosu; Syamal Kumar Dana

    2012-07-03T23:59:59.000Z

    We report a design of delay coupling for targeting desired synchronization in delay dynamical systems. We target synchronization, antisynchronization, lag-, antilag- synchronization, amplitude death (or oscillation death) and generalized synchronization in mismatched oscillators. A scaling of the size of an attractor is made possible in different synchronization regimes. We realize a type of mixed synchronization where synchronization, antisynchronization coexist in different pairs of state variables of the coupled system. We establish the stability condition of synchronization using the Krasovskii-Lyapunov function theory and the Hurwitz matrix criterion. We present numerical examples using the Mackey-Glass system and a delay R\\"{o}ssler system.

  18. Time dependence of delayed neutron emission for fissionable isotope identification

    SciTech Connect (OSTI)

    Kinlaw, M.T.; Hunt, A.W. [Idaho Accelerator Center, Idaho State University, Pocatello, Idaho 83209-8263 (United States); Department of Physics, Idaho State University, Pocatello, Idaho 83209-8106 (United States)

    2005-06-20T23:59:59.000Z

    The time dependence of delayed neutron emission was examined as a method of fissionable isotope identification. A pulsed bremsstrahlung photon beam was used to induce photofission reactions in {sup 238}U, {sup 232}Th, and {sup 239}Pu targets. The resulting delayed neutron emission was recorded between irradiating pulses and is a well-known technique for fissionable material detection. Monitoring the decay of delayed neutron emission between irradiating pulses demonstrates the ability to not only detect the presence of fissionable materials, but also to identify which fissionable isotope is present.

  19. Impact of delayed neutron precursor mobility in fissile solution systems

    SciTech Connect (OSTI)

    Kiedrowski, B. C. [X-Computational Physics Div., Los Alamos National Laboratory, MS A143, P.O. Box 1663, Los Alamos, NM 87545 (United States)

    2012-07-01T23:59:59.000Z

    A research version of the Monte Carlo software package MCNP6 is modified to incorporate advection and diffusion of delayed neutron precursors, resulting in the emission of delayed neutrons at locations different from the original fission sites. Results of two test problems, a pipe carrying flowing fissile solution and a sphere of fissile solution with precursor diffusion, show that the fission product mobility tends to perturb the fundamental mode, has a negative reactivity effect, and, perhaps most importantly, causes a decrease in the effective delayed neutron fraction. (authors)

  20. Coupled Thermal-Hydrological-Mechanical-Chemical Model And Experiments...

    Broader source: Energy.gov (indexed) [DOE]

    of mechanistic crack growth and grain contact models for chemically induced subcritical crack growth and pressure solution, with porosity-permeability changes * Conduct...

  1. Coupled Thermal-Hydrological-Mechanical-Chemical Model and Experiments...

    Broader source: Energy.gov (indexed) [DOE]

    of mechanistic crack growth and grain contact models for chemically induced subcritical crack growth and pressure solution, with porosity-permeability changes * Conduct...

  2. The stress field around two parallel edge cracks in a finite body

    E-Print Network [OSTI]

    Hardin, Patrick Wayne

    2012-06-07T23:59:59.000Z

    the application of the Schwarz alternating method in conjunction with complex mapping techniques for modelling the stress fields around two arbitrarily oriented cracks in an infinite body (see Fig. 1. 4). M P 0. 83W I. 83W Again 19. Isolated, Single...-Ended Crack Located in a Finite Body. " Zo r A I I 0 I Figure IA. Two Aibitnuily Oiiented Conchs Located in an Infinite Body. t CHAFIXR II FULL-FIELD REPRESENTATION OF THE STRESS FIELD SURROUNDING TWO EDGE CRACKS OVERVIEW OF THE METHODOLOGY USED...

  3. A numerical study of crack initiation in a bcc iron system based on dynamic bifurcation theory

    SciTech Connect (OSTI)

    Li, Xiantao, E-mail: xli@math.psu.edu [Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-10-28T23:59:59.000Z

    Crack initiation under dynamic loading conditions is studied under the framework of dynamic bifurcation theory. An atomistic model for BCC iron is considered to explicitly take into account the detailed molecular interactions. To understand the strain-rate dependence of the crack initiation process, we first obtain the bifurcation diagram from a computational procedure using continuation methods. The stability transition associated with a crack initiation, as well as the connection to the bifurcation diagram, is studied by comparing direct numerical results to the dynamic bifurcation theory [R. Haberman, SIAM J. Appl. Math. 37, 69–106 (1979)].

  4. Response Surfaces for optimal weight of cracked composite panels: noise and accuracy

    E-Print Network [OSTI]

    Melih Papila; Raphael T. Haftka

    Two levels of fidelity are used for minimum weight design of a composite blade-stiffened panel subject to crack propagation constraints. The low fidelity approach makes use of an equivalent strain constraint calculated by a closed form solution for the stress intensity factor. The high fidelity approach uses the stress intensity factor directly as the constraint and computes it from the stress distribution around the crack. A number of panels were optimized by both approaches for different values of applied load, crack length, and blade height, and response surface approximations for optimal weight as function of these configuration variables were constructed. Computational cost, noise and accuracy for the results are compared.

  5. E-Print Network 3.0 - av delay programming Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Complexity of Delay Management Technical Report 456, Department of Computer Science, ETH Zurich Summary: The Computational Complexity of Delay Management Technical Report 456,...

  6. Formulation and solution of the delayed gamma dose rate problem using the concept of effective delayed gamma production cross section

    SciTech Connect (OSTI)

    Liew, S.L.; Ku, L.P.

    1989-06-01T23:59:59.000Z

    With appropriate approximations, the delayed gamma dose rate problem can be formulated in terms of the effective delayed gamma production cross section. The coupled neutron-delayed-gamma transport equations then take the same form as the coupled neutron-prompt-gamma transport equations and they can, therefore, be solved directly in the same manner. This eliminates the need for the tedious and error prone flux coupling step in conventional calculations. Mathematical formulation and solution algorithms are derived. The advantages of this method are illustrated by an example of its application in the solution of a practical design problem. 62 refs., 10 figs., 1 tab.

  7. Opportunities for Process Monitoring Techniques at Delayed Access Facilities

    SciTech Connect (OSTI)

    Curtis, Michael M.; Gitau, Ernest TN; Johnson, Shirley J.; Schanfein, Mark; Toomey, Christopher

    2013-09-20T23:59:59.000Z

    Except for specific cases where the International Atomic Energy Agency (IAEA) maintains a continuous presence at a facility (such as the Japanese Rokkasho Reprocessing Plant), there is always a period of time or delay between the moment a State is notified or aware of an upcoming inspection, and the time the inspector actually enters the material balance area or facility. Termed by the authors as “delayed access,” this period of time between inspection notice and inspector entrance to a facility poses a concern. Delayed access also has the potential to reduce the effectiveness of measures applied as part of the Safeguards Approach for a facility (such as short-notice inspections). This report investigates the feasibility of using process monitoring to address safeguards challenges posed by delayed access at a subset of facility types.

  8. Preliminary Pulsing Experiments to Measure Delayed Neutron Emission Parameters

    SciTech Connect (OSTI)

    Charlton, W.S.; Parish, T.A.; Raman, S.

    1998-10-05T23:59:59.000Z

    Recent interest in delayed neutron parameters including comparisons between macroscopic (experimental) and microscopic (calculated) results have prompted a set of experiments using the 1MW Triga Reactor at the Texas A and M University (TAMU) Nuclear Science Center (NSC) designed to measure the complete set of seven-group delayed neutron parameters for several higher actinides. Operating the Nuclear Science Center Reactor (NSCR) in a pulsed mode, a complete set of delayed neutron parameters were measured for Np-237 and Am-243. The total delayed neutron yield per 100 fissions for Np-237 and Am-243 was found to be 1.14 {+-} 0.07 and 0.85 {+-} 0.05, respectively. Comparisons to previous measurements are made where such measurements are available.

  9. Robust crew pairing : delays analysis and implementation of optimization approaches

    E-Print Network [OSTI]

    Leroyer, Pierre, S.M. Massachusetts Institute of Technology

    2006-01-01T23:59:59.000Z

    With increasing delays and airport congestion that disturb airline operations, the development of robust schedules is becoming crucial. Increased traffic and poor weather are a few of the causes of airport congestion, ...

  10. Chimera and globally clustered chimera: Impact of time delay

    E-Print Network [OSTI]

    Sheeba, Jane H; Lakshmanan, M

    2010-01-01T23:59:59.000Z

    Following a short report of our preliminary results [Phys. Rev. E 79, 055203(R) (2009)], we present a more detailed study of the effects of coupling delay in diffusively coupled phase oscillator populations. We find that coupling delay induces chimera and globally clustered chimera (GCC) states in delay coupled populations. We show the existence of multi-clustered states that act as link between the chimera and the GCC states. A stable GCC state goes through a variety of GCC states, namely periodic, aperiodic, long-- and short--period breathers and becomes unstable GCC leading to global synchronization in the system, on increasing time delay. We provide numerical evidence and theoretical explanations for the above results and discuss possible applications of the observed phenomena.

  11. On delay-sensitive communication over wireless systems

    E-Print Network [OSTI]

    Liu, Lingjia

    2009-05-15T23:59:59.000Z

    consider a number of objectives. 1. Develop an integrated methodology for the analysis of wireless systems that support delay-sensitive applications based, in part, on large deviation theory. 2. Use this methodology to identify fundamental performance...

  12. Delayed neutron energy spectrum measurements of actinide waste isotopes

    E-Print Network [OSTI]

    Comfort, Christopher M.

    2012-06-07T23:59:59.000Z

    was irradiated using the Texas A&M Nuclear Science Center Reactor (NSCR). Three proton recoil detectors, operating individually, in conjunction with MCNP calculated response functions, were used to measure the delayed neutron energy spectra of each isotope...

  13. Utilization-based delay guarantee techniques and their applications

    E-Print Network [OSTI]

    Wang, Shengquan

    2009-05-15T23:59:59.000Z

    have become popular for both civilian and mission critical applications. The variable service capacity of a wireless link presents more of a challenge in providing delay-guaranteed services in wireless networks. Finally, we study ways to provide...

  14. additional delayed regional: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    results for five active galactic nuclei. We recovered velocity-delay maps using the maximum-entropy method for four objects: Mrk 335, Mrk 1501, 3C120, and PG2130+099. For the...

  15. Studies on the disbonding initiation of interfacial cracks.

    SciTech Connect (OSTI)

    McAdams, Brian J. (Lehigh University, Bethlehem, PA); Pearson, Raymond A. (Lehigh University, Bethlehem, PA)

    2005-08-01T23:59:59.000Z

    With the continuing trend of decreasing feature sizes in flip-chip assemblies, the reliability tolerance to interfacial flaws is also decreasing. Small-scale disbonds will become more of a concern, pointing to the need for a better understanding of the initiation stage of interfacial delamination. With most accepted adhesion metric methodologies tailored to predict failure under the prior existence of a disbond, the study of the initiation phenomenon is open to development and standardization of new testing procedures. Traditional fracture mechanics approaches are not suitable, as the mathematics assume failure to originate at a disbond or crack tip. Disbond initiation is believed to first occur at free edges and corners, which act as high stress concentration sites and exhibit singular stresses similar to a crack tip, though less severe in intensity. As such, a 'fracture mechanics-like' approach may be employed which defines a material parameter--a critical stress intensity factor (K{sub c})--that can be used to predict when initiation of a disbond at an interface will occur. The factors affecting the adhesion of underfill/polyimide interfaces relevant to flip-chip assemblies were investigated in this study. The study consisted of two distinct parts: a comparison of the initiation and propagation phenomena and a comparison of the relationship between sub-critical and critical initiation of interfacial failure. The initiation of underfill interfacial failure was studied by characterizing failure at a free-edge with a critical stress intensity factor. In comparison with the interfacial fracture toughness testing, it was shown that a good correlation exists between the initiation and propagation of interfacial failures. Such a correlation justifies the continuing use of fracture mechanics to predict the reliability of flip-chip packages. The second aspect of the research involved fatigue testing of tensile butt joint specimens to determine lifetimes at sub-critical load levels. The results display an interfacial strength ranking similar to that observed during monotonic testing. The fatigue results indicate that monotonic fracture mechanics testing may be an adequate screening tool to help predict cyclic underfill failure; however lifetime data is required to predict reliability.

  16. On the Approximation of Distributed-Delay Control Laws

    E-Print Network [OSTI]

    Mirkin, Leonid

    -dimensional internal feedback of the form P -P e-sh (here P is the delay-free plant and h is the loop delay) that aims can be replaced with . = Pa -P e-sh (modified/generalized Smith predictor), where Pa is a rational e-Agh (sI - Ag)-1 Bg. The finite impulse response (FIR) com- pletion h{G e-sh } of G e-sh is defined

  17. Device For Trapping Laser Pulses In An Optical Delay Line

    DOE Patents [OSTI]

    Yu, David U. L. (Rancho Palos Verdes, CA); Bullock, Donald L. (Los Angeles, CA)

    1997-12-23T23:59:59.000Z

    A device for maintaining a high-energy laser pulse within a recirculating optical delay line for a period time to optimize the interaction of the pulse with an electron beam pulse train comprising closely spaced electron micropulses. The delay line allows a single optical pulse to interact with many of the electron micropulses in a single electron beam macropulse in sequence and for the introduction of additional optical pulses to interact with the micropulses of additional electron beam macropulses. The device comprises a polarization-sensitive beam splitter for admitting an optical pulse to and ejecting it from the delay line according to its polarization state, a Pockels cell to control the polarization of the pulse within the delay line for the purpose of maintaining it within the delay line or ejecting it from the delay line, a pair of focusing mirrors positioned so that a collimated incoming optical pulse is focused by one of them to a focal point where the pulse interacts with the electron beam and then afterwards the pulse is recollimated by the second focusing mirror, and a timing device which synchronizes the introduction of the laser pulse into the optical delay line with the arrival of the electron macropulse at the delay line to ensure the interaction of the laser pulse with a prescribed number of electron micropulses in sequence. In a first embodiment of the invention, the principal optical elements are mounted with their axes collinear. In a second embodiment, all principal optical elements are mounted in the configuration of a ring.

  18. A study of the mechanism of laser welding defects in low thermal expansion superalloy GH909

    SciTech Connect (OSTI)

    Yan, Fei; Wang, Chunming, E-mail: yanxiangfei225@163.com; Wang, Yajun; Hu, Xiyuan; Wang, Tianjiao; Li, Jianmin; Li, Guozhu

    2013-04-15T23:59:59.000Z

    In this paper, we describe experimental laser welding of low-thermal-expansion superalloy GH909. The main welding defects of GH909 by laser in the weld are liquation cracks and porosities, including hydrogen and carbon monoxide porosity. The forming mechanism of laser welding defects was investigated. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum, X-ray diffractometer and other methodologies. The results demonstrated that porosities appearing in the central weld were related to incomplete removal of oxide film on the surface of the welding samples. The porosities produced by these bubbles were formed as a result of residual hydrogen or oxygenium in the weld. These elements failed to escape from the weld since laser welding has both a rapid welding speed and cooling rate. The emerging crack in the heat affected zone is a liquation crack and extends along the grain boundary as a result of composition segregation. Laves–Ni{sub 2}Ti phase with low melting point is a harmful phase, and the stress causes grain boundaries to liquefy, migrate and even crack. Removing the oxides on the surface of the samples before welding and carefully controlling technological parameters can reduce welding defects and improve formation of the GH909 alloy weld. - Highlights: ? It is a new process for the forming of GH909 alloy via laser welding. ? The forming mechanism of laser welding defects in GH909 has been studied. ? It may be a means to improve the efficiency of aircraft engine production.

  19. Technique for the identification of dominant delayed neutron precursors.

    SciTech Connect (OSTI)

    Loaiza, D. J. (David J.); Haskin, E. (Eric)

    2001-01-01T23:59:59.000Z

    A technique for the identification of delayed neutron precursors has been developed based on the product of cumulative yield and probability of neutron emission. The motivation behind this work is to fix the decay constants of delayed neutrons to those of the dominant delayed neutron precursors. The desirability of identifying a single set of decay constants that would apply to all fissionable isotopes and be independent of the neutron energy spectrum has been addressed by several authors. The main advantages of a fixed-decay constant representation are simplifying the analysis of epithemal and fast reactors with multiple fissioning isotopes, and improving the fit to experimental data while preserving the inferred positive reactivity scale associated with the original six-group representation. It is well known that 27 1 delayed neutron precursors exist, but only a select number of those precursors contribute significantly to the decay of delayed neutron. Using data compiled by England and Rider, which lists fission yield and probability of neutron emission values for the 27 1 known delayed neutron precursors in 32 fissioning systems, thirteen precursors were identified that are consistently dominant for alI fissioning systems.

  20. Delayed-fission properties of neutron-deficient americium nuclei

    SciTech Connect (OSTI)

    Hall, H.L. (California Univ., Berkeley, CA (USA). Dept. of Chemistry)

    1989-10-23T23:59:59.000Z

    Characteristics of the delayed-fission decay mode in light americium nuclei have been investigated. Measurements on the unknown isotopes {sup 230}Am and {sup 236}Am were attempted, and upper limits on the delayed-fission branches of these nuclei were determined. Evidence of the existence of {sup 236}Am was observed in radiochemical separations. Total kinetic energy and mass-yield distributions of the electron-capture delayed-fission mode were measured for {sup 232}Am (t{sub 1/2} = 1.31 {plus minus} 0.04 min) and for {sup 234}Am (t{sub 1/2} = 2.32 {plus minus} 0.08 min), and delayed-fission probabilities of 6.9 {times} 10{sup {minus}4} and 6.6 {times} 10{sup {minus}5}, respectively, were determined. The total kinetic energy and the asymmetric mass-yield distributions are typical of fission of mid-range actinides. No discernible influence of the anomalous triple-peaked mass division characteristic of the thorium-radium region was detected. Measurements of the time correlation between the electron-capture x-rays and the subsequent fission conform that the observed fissions arise from the electron-capture delayed-fission mechanism. Delayed fission has provided a unique opportunity to extend the range of low-energy fission studies to previously inaccessible regions. 71 refs., 44 figs., 13 tabs.

  1. Evaluation of the filler effects on fatique cracking and permanent deformation of asphalt concrete mixtures

    E-Print Network [OSTI]

    Izzo, Richard P

    1997-01-01T23:59:59.000Z

    The addition of hydrated lime to asphalt has shown to be beneficial with an improvement in the Theological properties of the binder, as well as resistance to permanent deformation (rutting) and fatigue cracking of asphalt concrete mixtures...

  2. A program to design asphalt concrete overlays to mitigate reflection cracking

    E-Print Network [OSTI]

    Satyanarayana Rao, Sindhu

    2002-01-01T23:59:59.000Z

    of the research are to understand the occurrence and behavior of reflection cracking and for devising ways of mitigating them and to put together an effective and complete package of computer programs to design asphalt concrete overlays. Another primary objective...

  3. Cracked lifting lug welds on ten-ton UF{sub 6} cylinders

    SciTech Connect (OSTI)

    Dorning, R.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31T23:59:59.000Z

    Ten-ton, Type 48X, UF{sub 6} cylinders are used at the Portsmouth Gaseous Diffusion Plant to withdraw enriched uranium hexafluoride from the cascade, transfer enriched uranium hexafluoride to customer cylinders, and feed enriched product to the cascade. To accomplish these activities, the cylinders are lifted by cranes and straddle carriers which engage the cylinder lifting lugs. In August of 1988, weld cracks on two lifting lugs were discovered during preparation to lift a cylinder. The cylinder was rejected and tagged out, and an investigating committee formed to determine the cause of cracking and recommend remedial actions. Further investigation revealed the problem may be general to this class of cylinder in this use cycle. This paper discusses the actions taken at the Portsmouth site to deal with the cracked lifting lug weld problem. The actions include inspection activities, interim corrective actions, metallurgical evaluation of cracked welds, weld repairs, and current monitoring/inspection program.

  4. Reaction kinetics of olefin saturation in the hydrodesulfurization of fluid catalytic cracked naphtha

    E-Print Network [OSTI]

    Schumann, Brian Herbert

    2012-06-07T23:59:59.000Z

    U.S. governmental agencies are calling for strict environmental regulations on the quality of gasoline. Fluid catalytic cracked naphtha is an important blending component of the gasoline pool. The majority of the sulfur in the gasoline pool comes...

  5. THE EFFECT OF SILICON ON THE ENVIRONMENTAL CRACKING BEHAVIOR OF A HIGH STRENGTH STEEL

    E-Print Network [OSTI]

    Cedeno, M.H.C.

    2010-01-01T23:59:59.000Z

    Low-Alloy, High-Strength Steel, Advanced Research ProjectsTests of High Strength Steels, BISRA Report September 1971.Cracking in High Strength Steels and in Titanium and

  6. Linear elastic fracture mechanics in anisotropic solids : application to fluid-driven crack propagation

    E-Print Network [OSTI]

    Laubie, Hadrien Hyacinthe

    2013-01-01T23:59:59.000Z

    Fracture mechanics is a field of continuum mechanics with the objective to predict how cracks initiate and propagate in solids. It has a wide domain of application. While aerospace engineers want to make sure a defect in ...

  7. On the fracture toughness of ferroelectric ceramics with electric field applied parallel to the crack front

    E-Print Network [OSTI]

    On the fracture toughness of ferroelectric ceramics with electric field applied parallel crack growth. The effects of electric field on the fracture toughness of both initially unpoled and poled materials are investigated. Results for the predicted fracture toughness, remanent strain

  8. Spatial and Temporal Distribution of Desiccation Cracks in Shrink-Swell Soils

    E-Print Network [OSTI]

    Neely, Haly Lury

    2014-04-17T23:59:59.000Z

    Soil crack volume estimates, which are important for hydrology models on shrink-swell soils, are currently based on field measurements of vertical shrinkage and an assumption of isotropic shrinkage; however, few studies have validated the resulting...

  9. Integrating Gas Turbines with Cracking Heaters - Impact on Emissions and Energy Efficiency

    E-Print Network [OSTI]

    Platvoet, E.

    2011-01-01T23:59:59.000Z

    Turbine Exhaust Gas (TEG) contains high levels of oxygen, typically 15 vol. percent, due to gas turbine blade material temperature limits. As such it can be used as an oxidant for combustion in cracking furnaces and reformers. Its high temperature...

  10. Aluminum nitride transitional layer for reducing dislocation density and cracking of AIGan epitaxial films

    DOE Patents [OSTI]

    Allerman, Andrew A. (Tijeras, NM); Crawford, Mary H. (Albuquerque, NM); Koleske, Daniel D. (Albuquerque, NM); Lee, Stephen R. (Albuquerque, NM)

    2011-03-29T23:59:59.000Z

    A denticulated Group III nitride structure that is useful for growing Al.sub.xGa.sub.1-xN to greater thicknesses without cracking and with a greatly reduced threading dislocation (TD) density.

  11. Effect of oxygen potential on high temperature crack growth in alloy 617

    E-Print Network [OSTI]

    Benz, Julian K

    2009-01-01T23:59:59.000Z

    The effect of oxygen partial pressure on crack growth rates in Alloy 617 has been studied using both static and fatigue loading at 650°C. Tests were conducted at a constant stress intensity factor, K, for static loading ...

  12. Fission product chain yields and delayed neutrons: ANS standards 5. 2 and 5. 8

    SciTech Connect (OSTI)

    England, T.R. (Los Alamos National Lab., NM (United States)); Brady, M.C. (Oak Ridge National Lab., TN (United States)); Rider, B.F.

    1990-01-01T23:59:59.000Z

    Chain yields are the addition of the direct values along constant (Z + N) paths. The addition must also account for decay branching, especially for delayed neutrons that couple the mass chains. The result is the familiar double-humped plot of yield per fission versus mass number. The lines of stable nuclides and most probable yield are shown in the (Z,N) plane. Some modern measurements provide direct yields; other provide cumulative values for long-lived or stable products. Yield evaluations must account for each type of measurement and the degree of decay coupling, beginning with direct yields. For some fissioning nuclides at thermal or fast neutron incident energies, the amount of data is enormous; and for other nuclide-energy combinations, the data must be developed from systematics. Many applications of chain yields can use the same systematics to estimate independent values. The ANS 5.2 standard is currently in rough draft form for comment from working group members.

  13. Dominant delayed neutron precursors to model reactivity predictions for multiple fissioning nuclides

    SciTech Connect (OSTI)

    Loaiza, D.J.; Haskin, F.E.

    2000-01-01T23:59:59.000Z

    The product of cumulative yield and probability of neutron emission is used to assess the relative importance of known delayed neutron precursors. Thirteen precursors are consistently dominant. Nonlinear fits to experimental delayed neutron decay data distinguish the decay constants of the three longest-lived dominant precursors: {sup 87}Br, {sup 137}I, and {sup 88}Br. Sensitivity calculations based on a six-to seven-group transformation lead to a proposed seven-group formulation in which the group decay constants are those of dominant precursors: {sup 87}Br, {sup 137}I, {sup 88}Br, {sup 93}Rb, {sup 139}I, {sup 91}Br, and {sup 96}Rb. An alternative six-group formulation is obtained by using the mean of the {sup 137}I and {sup 88}Br decay constants for group 2. The use of the suggested dominant precursor decay constants improves the goodness of fit to experimental data compared to that obtained from nonlinear least squares in which both group yields and decay constants are determined empirically. Reactivity worth and transient analyses confirm that the positive reactivity scale is preserved in the transformation. A known bias in the negative reactivity scale is eliminated by forcing the half-life of the longest-lived group to be the 55.9-s half-life of {sup 87}Br. The proposed use of dominant precursor decay constants offers significant simplifications in data analysis and the analysis of fast, epithermal, and thermal reactors with multiple fissioning nuclides.

  14. Electrochemical aspects of stress-corrosion cracking in. cap alpha. -brass

    SciTech Connect (OSTI)

    Burstein, G T; Newman, R C

    1981-01-01T23:59:59.000Z

    This paper considers a number of aspects of the stress-corrosion cracking of brass from the point of view of the localized electrochemical processes occurring at the tip of a propagating crack. The principal system examined is the intergranular SCC of 70-30 brass in near-neutral ammoniacal solutions, for which a detailed mechanism is developed. In addition, the effects of nitrite ions in promoting SCC of both brass and copper are considered.

  15. A quantitative determination of the conditions for hot cracking during welding for aluminum alloys

    E-Print Network [OSTI]

    Steenbergen, James Everett

    1969-01-01T23:59:59.000Z

    A QUANTITATIVE DETERMINATION OF THE CONDITIONS FOR HOT CRACKING DURING WELDING FOR ALUMINUM ALLOYS A Thesis by JAMES EVERETT STEENBERGEN Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE January 1969 Major Subject: Materials Engineering A QUANTITATIVE DETERMINATION OF THE CONDITIONS FOR HOT CRACKING DURING WELDING FOR ALUMINUM ALLOYS A Thesis by JAMES EVERETT STEENBERGEN (Chairman of Committee) ( ead...

  16. Geometry dependence of crack growth resistance curves in thin sheet aluminum alloys

    E-Print Network [OSTI]

    Stricklin, Lance Lee

    1988-01-01T23:59:59.000Z

    GEOMETRY DEPENDENCE OF CRACK GROWTH RESISTANCE CURVES IN THIN SHEET ALUMINUM ALLOYS A Thesis by LANCE LEE STRICKLIN Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE December 1988 Major Subject: Mechanical Engineering GEOMETRY DEPENDENCE OF CRACK GROWTH RESISTANCE CURVES IN THIN SHEET ALUMINUM ALLOYS A Thesis by LANCE LEE STRICKLIN Approved as to style and content by: Ted L. Anderson...

  17. A finite element model for laminated composite plates with matrix cracks and delaminations

    E-Print Network [OSTI]

    Buie, Kevin Daniel

    1988-01-01T23:59:59.000Z

    A FINITE ELEMENT MODEL FOR LAMINATED COMPOSITE PLATES WITH MATRIX CRACKS AND DELAMINATIONS A Thesis by KEVIN DANIEL BUIE Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of' the requirements... for the degree of MASTER OF SCIENCE December 1988 Major Subject: Aerospace Engineering A FINITE ELEMENT MODEL FOR LAMINATED COMPOSITE PLATES WITH MATRIX CRACKS AND DELAMINATIONS A Thesis by KEVIN DANIEL BUIE Approved as to style and content by: David H...

  18. On grouting using a suspension of ultrafine clay on artificially cracked rock samples

    SciTech Connect (OSTI)

    Ito, Y.; Sakaguchi, T.; Nishiyama, K. [Kumagai Gumi Co., Ltd., Tokyo (Japan). Nuclear and Energy Dept.; Fujiwara, A. [Radioactive Waste Management Center, Tokyo (Japan). Second Research Div.

    1993-12-31T23:59:59.000Z

    Recently there has been increasing social interest in the effective disposal of low-level radioactive wastes. The use of underground rock caverns is considered as a possible repository space. This paper presents a new grouting method which uses a suspension of liquefied ultrafine clay in fractured rock masses. In order to demonstrate the effect to block open cracks, two experiments were carried out on large-sized granite samples with open cracks. The experiments proved the method to be highly effective.

  19. Mode I transverse cracking in an epoxy and a graphite fiber reinforced epoxy

    E-Print Network [OSTI]

    Williams, David Robert

    1981-01-01T23:59:59.000Z

    tension specimens tested under intermittent fixed grip conditions. The graphite/epoxy composite manifests a significant increase in fracture toughness with crack length as the crack length to specimen width ratio I'a/w) exceeds 0. 5. This increase... in toughness is correlated with an increase in fiber break- age and pullout and permanent matrix deformation. Results obtained in this study are compared with results from studies of delamination fracture toughness of the same composite material to show...

  20. Laboratory Evaluation of Hot-Mix Asphalt Concrete Fatigue Cracking Resistance

    E-Print Network [OSTI]

    Jamison, Brandon Parker

    2012-02-14T23:59:59.000Z

    LABORATORY EVALUATION OF HOT-MIX ASPHALT CONCRETE FATIGUE CRACKING RESISTANCE A Thesis by BRANDON PARKER JAMISON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 2010 Major Subject: Civil Engineering LABORATORY EVALUATION OF HOT-MIX ASPHALT CONCRETE FATIGUE CRACKING RESISTANCE A Thesis by BRANDON PARKER JAMISON Submitted to the Office of Graduate...

  1. Sulphide stress cracking resistance of supermartensitic stainless steel for OCTG

    SciTech Connect (OSTI)

    Scoppio, L.; Barteri, M. [Centro Sviluppo Materiali S.p.A., Rome (Italy); Cumino, G. [Dalmine Tubi Industriali S.r.l., Bergamo (Italy)

    1997-08-01T23:59:59.000Z

    Supermartensitic stainless steels, recently made available as oil country tubular goods (OCTG), have been developed as a valuable cost effective alternative to duplex stainless steel for high CO{sub 2}, medium/high chlorides, and very low H{sub 2}S environments. Experimental tests were carried out to determine the localized corrosion and the sulfide stress cracking (SSC) resistance of supermartensitic steel UNS S41425 to be used as OCTG in slightly sour oil and gas wells and to compare its performance with standard L80 API grade UNS S42000 13% Cr steel, considered as a reference. Supermartensitic steels with yield range as per L80, C95, P110, API5CT, were developed and corrosion and mechanical properties were determined. The influence of different chloride contents (NaCl 10 {divided_by} 50 g/l), hydrogen sulfide partial pressure (0.1 {divided_by} 100 kPa) and pH (2.7 {divided_by} 4.5) has been investigated in order to simulate production service conditions. Modified NACE constant load test and slow strain rate (SSR) test were performed. SSR gave the most severe evaluation for the SSC resistance. In the SSR test supermartensitic steel is deeply influenced by the chloride concentration. Supermartensitic steel corrosion resistance is by far superior to that of 13% Cr.

  2. Weibull Effective Area for Hertzian Ring Crack Initiation Stress

    SciTech Connect (OSTI)

    Jadaan, Osama M. [University of Wisconsin, Platteville; Wereszczak, Andrew A [ORNL; Johanns, Kurt E [ORNL

    2011-01-01T23:59:59.000Z

    Spherical or Hertzian indentation is used to characterize and guide the development of engineered ceramics under consideration for diverse applications involving contact, wear, rolling fatigue, and impact. Ring crack initiation can be one important damage mechanism of Hertzian indentation. It is caused by sufficiently-high, surface-located, radial tensile stresses in an annular ring located adjacent to and outside of the Hertzian contact circle. While the maximum radial tensile stress is known to be dependent on the elastic properties of the sphere and target, the diameter of the sphere, the applied compressive force, and the coefficient of friction, the Weibull effective area too will be affected by those parameters. However, the estimations of a maximum radial tensile stress and Weibull effective area are difficult to obtain because the coefficient of friction during Hertzian indentation is complex, likely intractable, and not known a priori. Circumventing this, the Weibull effective area expressions are derived here for the two extremes that bracket all coefficients of friction; namely, (1) the classical, frictionless, Hertzian case where only complete slip occurs, and (2) the case where no slip occurs or where the coefficient of friction is infinite.

  3. Automated inspection of surface breaking cracks using GMR sensor arrays

    SciTech Connect (OSTI)

    Pelkner, Matthias; Reimund, Verena; Erthner, Thomas; Panke, Nicolai; Kreutzbruck, Marc [BAM Federal Institute for Material Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

    2014-02-18T23:59:59.000Z

    We present a prototype for automated magnetic stray field testing of ferromagnetic roller bearings. For this purpose NDE-adapted GMR sensor arrays (giant magneto resistance) are used for the detection of surface breaking cracks. The sensors are miniaturized down to the lower ?m-regime to achieve adequate spatial resolution. In doing so, sensor arrays with up to 48 elements are used to inspect the bearing surface within a few seconds only. In contrast to magnetic particle inspection (MPI), where the global magnetization requires a further inspection step and succeeding demagnetization, the presented prototype only locally magnetize the surface area in the vicinity of the GMR Sensors. For the local magnetization, the applied sub-surface magnetic field was simulated and proofed for detecting flaws with a depth of a few 10 ?m. By multiplexing the sensor array with an adapted read out electronics we quasi simultaneously detect the normal field component of about 100?m above the surface. The detection of artificial notches with a depth of 40 ?m and more could be resolved with a SNR better than 20 dB. The presented testing facility is fast and provides a step towards automated testing of safety relevant steel components.

  4. Methodology for extracting local constants from petroleum cracking flows

    DOE Patents [OSTI]

    Chang, Shen-Lin (Woodridge, IL); Lottes, Steven A. (Naperville, IL); Zhou, Chenn Q. (Munster, IN)

    2000-01-01T23:59:59.000Z

    A methodology provides for the extraction of local chemical kinetic model constants for use in a reacting flow computational fluid dynamics (CFD) computer code with chemical kinetic computations to optimize the operating conditions or design of the system, including retrofit design improvements to existing systems. The coupled CFD and kinetic computer code are used in combination with data obtained from a matrix of experimental tests to extract the kinetic constants. Local fluid dynamic effects are implicitly included in the extracted local kinetic constants for each particular application system to which the methodology is applied. The extracted local kinetic model constants work well over a fairly broad range of operating conditions for specific and complex reaction sets in specific and complex reactor systems. While disclosed in terms of use in a Fluid Catalytic Cracking (FCC) riser, the inventive methodology has application in virtually any reaction set to extract constants for any particular application and reaction set formulation. The methodology includes the step of: (1) selecting the test data sets for various conditions; (2) establishing the general trend of the parametric effect on the measured product yields; (3) calculating product yields for the selected test conditions using coupled computational fluid dynamics and chemical kinetics; (4) adjusting the local kinetic constants to match calculated product yields with experimental data; and (5) validating the determined set of local kinetic constants by comparing the calculated results with experimental data from additional test runs at different operating conditions.

  5. Hydrogen-induced cracking along the fusion boundary of dissimilar metal welds

    SciTech Connect (OSTI)

    Rowe, M.D.; Nelson, T.W.; Lippold, J.C. [Ohio State Univ., Columbus, OH (United States)

    1999-02-01T23:59:59.000Z

    Presented here are the results from a series of experiments in which dissimilar metals welds were made using the gas tungsten arc welding process with pure argon or argon-6% hydrogen shielding gas. The objective was to determine if cracking near the fusion boundary of dissimilar metal welds could be caused by hydrogen absorbed during welding and to characterize the microstructures in which cracking occurred. Welds consisted of ER308 and ER309LSi austenitic stainless steel and ERNiCr-3-nickel-based filler metals deposited on A36 steel base metal. Cracking was observed in welds made with all three filler metals. A ferrofluid color metallography technique revealed that cracking was confined to regions in the weld metal containing martensite. Microhardness indentations indicated that martensitic regions in which cracking occurred had hardness values from 400 to 550 HV. Cracks did not extend into bulk weld metal with hardness less than 350 HV. Martensite formed near the fusion boundary in all three filler metals due to regions of locally increased base metal dilution.

  6. Effects of hydrogen on electropotential monitoring of stress corrosion crack growth

    SciTech Connect (OSTI)

    Thompson, C.D.; Carey, D.M.; Perazzo, N.L.

    1997-08-01T23:59:59.000Z

    Electropotential monitoring (EPM) has a crack growth measurement resolution that is an order of magnitude greater than methods that rely on crack mouth opening displacement. However, two phenomena have been identified that compromise the accuracy of the EPM technique. Coolant hydrogen concentrations above those needed to chemically reduce nickel oxide to metallic nickel cause EPM to underestimate the true crack length. The metallic nickel provides an electrical conduction path at contact points across the irregular crack surface thereby lowering the EPM potential. The coolant hydrogen concentration at which this reduction occurs is temperature dependent and correlates with an abrupt decrease in the rate of SCC crack growth. It was also found that EPM can indicate large crack growth when none actually exists. At temperatures > 315 C (600 F) the electrical resistivity of mill annealed Alloy 600 increased by as much as 5% in a period of weeks or months. Each 1% increase in resistivity results in a bias in the EPM indicated cracklength of about 0.2 mm (0.008 inches). Smaller changes in the electrical resistivity of other alloys have been measured which rank as EN52> X-750> 304SS> nickel. It has been shown that these resistivity changes occur during exposure to high temperature water or inert gas. Strategies to minimize the effects of these two phenomena on EPM measurement are discussed.

  7. Steady-state propagation of a Mode III crack in couple stress elastic materials

    E-Print Network [OSTI]

    G. Mishuris; A. Piccolroaz; E. Radi

    2012-07-14T23:59:59.000Z

    This paper is concerned with the problem of a semi-infinite crack steadily propagating in an elastic solid with microstructures subject to antiplane loading applied on the crack surfaces. The loading is moving with the same constant velocity as that of the crack tip. We assume subsonic regime, that is the crack velocity is smaller than the shear wave velocity. The material behaviour is described by the indeterminate theory of couple stress elasticity developed by Koiter. This constitutive model includes the characteristic lengths in bending and torsion and thus it is able to account for the underlying microstructure of the material as well as for the strong size effects arising at small scales and observed when the representative scale of the deformation field becomes comparable with the length scale of the microstructure, such as the grain size in a polycrystalline or granular aggregate. The present analysis confirms and extends earlier results on the static case by including the effects of crack velocity and rotational inertia. By adopting the criterion of maximum total shear stress, we discuss the effects of microstructural parameters on the stability of crack propagation.

  8. Sonic IR crack detection of aircraft turbine engine blades with multi-frequency ultrasound excitations

    SciTech Connect (OSTI)

    Zhang, Ding; Han, Xiaoyan [Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202 (United States); Newaz, Golam [Department of Mechanical Engineering, Wayne State University, Detroit, MI 48202 (United States)

    2014-02-18T23:59:59.000Z

    Effectively and accurately detecting cracks or defects in critical engine components, such as turbine engine blades, is very important for aircraft safety. Sonic Infrared (IR) Imaging is such a technology with great potential for these applications. This technology combines ultrasound excitation and IR imaging to identify cracks and flaws in targets. In general, failure of engine components, such as blades, begins with tiny cracks. Since the attenuation of the ultrasound wave propagation in turbine engine blades is small, the efficiency of crack detection in turbine engine blades can be quite high. The authors at Wayne State University have been developing the technology as a reliable tool for the future field use in aircraft engines and engine parts. One part of the development is to use finite element modeling to assist our understanding of effects of different parameters on crack heating while experimentally hard to achieve. The development has been focused with single frequency ultrasound excitation and some results have been presented in a previous conference. We are currently working on multi-frequency excitation models. The study will provide results and insights of the efficiency of different frequency excitation sources to foster the development of the technology for crack detection in aircraft engine components.

  9. Thermal comfort during surgery

    E-Print Network [OSTI]

    Manning, David Harold

    1978-01-01T23:59:59.000Z

    THERMAL COMFORT DURING SURGERY A Thesis by DAVID HAROLD MANNING Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1978 Major Subject: Industrial... Engineering THERMAL COMFORT DURING SURGERY A Thesis by DAVID HAROLD MANNING Approved as to style and content by: airman of C it ee Head of Department Member Me er December 1978 ABSTRACT Thermal Comfort During Surgery (December 1978) David Harold...

  10. Thermal Infrared Remote Sensing

    E-Print Network [OSTI]

    Thermal Infrared Remote Sensing Thermal Infrared Remote Sensing #12;0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4 and x-ray Ultraviolet Infrared Microwave and radio waves Wavelength in meters (m) Electromagnetic.77 700 red limit 30k0.041 2.48 green500 near-infrared far infrared ultraviolet Thermal Infrare refers

  11. Thermal neutron imaging in an active interrogation environment

    SciTech Connect (OSTI)

    Vanier,P.E.; Forman, L., and Norman, D.R.

    2009-03-10T23:59:59.000Z

    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

  12. Thermal Neutron Imaging in an Active Interrogation Environment

    SciTech Connect (OSTI)

    Vanier, Peter E. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Forman, Leon [Ion Focus Technology, Inc., Miller Place, NY 11764 (United States); Norman, Daren R. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

    2009-03-10T23:59:59.000Z

    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutron-emitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

  13. Contact fatigue behavior and gas cell thermal wave NDE of sintered reaction bonded silicon nitride

    SciTech Connect (OSTI)

    Barla, J.R.; Edler, J.P.; Lin, H. [Eaton Corp. R & D, Southfield, MI (United States)] [and others

    1996-12-31T23:59:59.000Z

    Silicon nitride is being evaluated for potential applications as structural components subjected to contact fatigue loading. A new testing and evaluation methodology for evaluation of Hertzian contact fatigue damage in ceramic materials has been developed and is described. Contact fatigue damage is induced in three test specimens simultaneously. The material investigated is Eaton Corporation`s low cost E - Process Silicon Nitride. Tests were conducted at several Hertzian stress levels to evaluate contact fatigue damage behavior. Gas cell thermal wave NDE was employed to study the induced subsurface damage. Damage behavior was also investigated using optical microscopy. Two specimens were evaluated in detail; one that was tested for 17,400 cycles, P{sub max} = 2700 N and one that was tested for 1 x 10{sup 6} cycles, P{sub max} = 1800 N. The 2700 N specimen has a partial cone crack and contains a small concentration of vertical and shallow horizontal cracks. No evidence of a cone crack was detected on the 1800 N specimen. However, a larger concentration of horizontal microcracks at and just below the surface is present in this specimen, with particle debris in and around the surface contact area. Correlation of the optical microscopy observations with gas cell thermal wave NDE of the subsurface damage in these two specimens is discussed.

  14. MacroscoMacroscopic Cracking Determination in LaBS Glasspic Cracking Determination in LaBS Glass

    SciTech Connect (OSTI)

    Marra, James

    2005-08-01T23:59:59.000Z

    The DOE/EM plans to conduct the Plutonium Vitrification Project at the Savannah River Site (SRS). An important part of this project is to reduce the attractiveness of the plutonium by fabricating a plutonium glass form and immobilizing the Pu form within the high level waste (HLW) glass prepared in the Defense Waste Processing Facility (DWPF). This requires that a project schedule that is consistent with EM plans for DWPF and cleanup of the SRS be developed. Critical inputs to key decisions in the vitrification project schedule are near-term data that will increase confidence that the lanthanide borosilicate (LaBS) glass product is suitable for disposal in the Yucca Mountain Repository. A workshop was held on April 28, 2005 at Bechtel SAIC Company (BSC) facility in Las Vegas, NV to define the near term data needs. Dissolution rate data and the fate of plutonium oxide and the neutron absorbers during the dissolution process were defined as key data needs. A suite of short-term tests were defined at the workshop to obtain the needed data. The objectives of these short-term tests are to obtain data that can be used to show that the dissolution rate of a LaBS glass is acceptable and to show that the extent of Pu separation from neutron absorbers, as the glass degrades and dissolves, is not likely to lead to criticality concerns. An additional data need was identified regarding the degree of macroscopic cracking and/or voiding that occurs during processing of the Pu glass waste form and subsequent pouring of HLW glass in the DWPF. A final need to evaluate new frit formulations that may increase the durability of the plutonium glass and/or decrease the degree to which neutron absorbers separate from the plutonium during dissolution was identified. This task plan covers the need to evaluate the degree of macroscopic cracking and/or voiding that occurs during processing of the Vitrified Plutonium Waste Form (i.e. the can-in-canister configuration containing the vitrified Pu product). Separate task plans were developed for Pu glass performance testing of the current baseline LaBS glass composition and development of alternative frit formulations. Recent results from Pressurized Unsaturated Flow (PUF) testing showed the potential separation of Pu from Gd during the glass dissolution process [3]. Post-test analysis of the LaBS glass from a 6-year PUF test showed a region where Pu had apparently accumulated in a Pu-bearing disk-like phase that had become separated from neutron absorber (Gd). It should be noted that this testing was conducted on the early LaBS Frit A glass composition that was devoid of HfO{sub 2} as a neutron absorber. PUF testing is currently being initiated using the LaBS Frit B composition that contains HfO{sub 2}. The potential for fissile material and neutron absorber separation is a criticality risk for the repository. The surface area that is available for leaching (i.e. due to the degree of cracking or voiding within the Pu glass cylinder) is a factor in modeling the amount of fissile material and neutron absorber released during the dissolution process. A mathematical expression for surface area is used in the Total Systems Performance Assessment (TSPA) performed by BSC personnel. Specifically, the surface area available for leaching is being used in current external criticality assessments. The planned processing steps for producing a VPWF assembly involves processing Pu feed and LaBS frit to produce a can of Pu LaBS glass, packaging this can into a second can (i.e. bagless transfer) for removal from the glovebox processing environment, placing a series of bagless transfer cans into a DWPF canister, and pouring HLW glass into the DWPF canister to encapsulate bagless transfer cans. The objective of this task is to quantify the degree of cracking and/or voiding that will occur during the processing of the VPWF.

  15. Variable pressure thermal insulating jacket

    DOE Patents [OSTI]

    Nelson, P.A.; Malecha, R.F.; Chilenskas, A.A.

    1994-09-20T23:59:59.000Z

    A device for controlled insulation of a thermal device is disclosed. The device includes a thermal jacket with a closed volume able to be evacuated to form an insulating jacket around the thermal source. A getter material is in communication with the closed volume of the thermal jacket. The getter material can absorb and desorb a control gas to control gas pressure in the volume of the thermal jacket to control thermal conductivity in the thermal jacket. 10 figs.

  16. NANO REVIEW Open Access Thermal conductivity and thermal boundary

    E-Print Network [OSTI]

    Boyer, Edmond

    NANO REVIEW Open Access Thermal conductivity and thermal boundary resistance of nanostructures and the thermal transport prop- erties is a key point to design materials with preferred thermal properties with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity

  17. DEVELOPMENT AND CONSTRUCTION OF LOW-CRACKING HIGH-PERFORMANCE CONCRETE (LC-HPC) BRIDGE DECKS: FREE SHRINKAGE TESTS, RESTRAINED RING TESTS, CONSTRUCTION EXPERIENCE, AND CRACK SURVEY RESULTS

    E-Print Network [OSTI]

    Yuan, Jiqiu

    2011-12-31T23:59:59.000Z

    The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained during the construction of 13 LC-HPC bridge decks in Kansas, along...

  18. Inuence of foreign-object damage on crack initiation and early crack growth during high-cycle fatigue of Ti6Al4V

    E-Print Network [OSTI]

    Ritchie, Robert

    incidence of late of HCF- related engine failures, particularly involving titanium alloy fan and compressor.g., stones, primarily on the fan blades, can cause (de- pending on the impact severity) immediate blade of small surface fatigue cracks in a Ti±6Al±4V alloy, processed for typical turbine blade applications

  19. Thermal protection apparatus

    DOE Patents [OSTI]

    Bennett, G.A.; Elder, M.G.; Kemme, J.E.

    1984-03-20T23:59:59.000Z

    The disclosure is directed to an apparatus for thermally protecting sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components such as electronics to a heat sink such as ice.

  20. Mechanical Engineering & Thermal Group

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    Mechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has, and ground- based mechanical systems. Instrument Design Building on decades of design experience that has evolved with the complexity of instrument design demands, LASP mechanical engineers develop advanced

  1. Thermal protection apparatus

    DOE Patents [OSTI]

    Bennett, Gloria A. (Los Alamos, NM); Elder, Michael G. (Los Alamos, NM); Kemme, Joseph E. (Albuquerque, NM)

    1985-01-01T23:59:59.000Z

    An apparatus which thermally protects sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components to a heat sink such as ice.

  2. Acoustic Emission and Guided Ultrasonic Waves for Detection and Continuous Monitoring of Cracks in Light Water Reactor Components

    SciTech Connect (OSTI)

    Meyer, Ryan M.; Coble, Jamie B.; Ramuhalli, Pradeep; Watson, Bruce E.; Cumblidge, Stephen E.; Doctor, Steven R.; Bond, Leonard J.

    2012-06-28T23:59:59.000Z

    Acoustic emission (AE) and guided ultrasonic waves (GUW) are considered for continuous monitoring and detection of cracks in Light Water Reactor (LWR) components. In this effort, both techniques are applied to the detection and monitoring of fatigue crack growth in a full scale pipe component. AE results indicated crack initiation and rapid growth in the pipe, and significant GUW responses were observed in response to the growth of the fatigue crack. After initiation, the crack growth was detectable with AE for approximately 20,000 cycles. Signals associated with initiation and rapid growth where distinguished based on total rate of activity and differences observed in the centroid frequency of hits. An intermediate stage between initiation and rapid growth was associated with significant energy emissions, though few hits. GUW exhibit a nearly monotonic trend with crack length with an exception of measurements obtained at 41 mm and 46 mm.

  3. Environmentally assisted cracking in light water reactors. Semiannual report, July 1998-December 1998.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Gruber, E. E.; Kassner, T. F.; Ruther, W. E.; Shack, W. J.; Smith, J. L.; Soppet, W. K.; Strain; R. V. (Energy Technology); ( APS-USR)

    1999-10-01T23:59:59.000Z

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors from July 1998 to December 1998. Topics that have been investigated include (a) environmental effects on fatigue S-N behavior of primary pressure boundary materials, (b) irradiation-assisted stress corrosion cracking of austenitic stainless steels (SSs), and (c) EAC of Alloys 600 and 690. Fatigue tests have been conducted to determine the crack initiation and crack growth characteristics of austenitic SSs in LWR environments. Procedures are presented for incorporating the effects of reactor coolant environments on the fatigue life of pressure vessel and piping steels. Slow-strain-rate tensile tests and posttest fractographic analyses were conducted on several model SS alloys irradiated to {approx}0.3 and 0.9 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV) in helium at 289 C in the Halden reactor. The results have been used to determine the influence of alloying and impurity elements on the susceptibility of these steels to irradiation-assisted stress corrosion cracking. Fracture toughness J-R curve tests were also conducted on two heats of Type 304 SS that were irradiated to {approx}0.3 x 10{sup 21} n {center_dot} cm{sup -2} in the Halden reactor. Crack-growth-rate tests have been conducted on compact-tension specimens of Alloys 600 and 690 under constant load to evaluate the resistance of these alloys to stress corrosion cracking in LWR environments.

  4. Solar thermal aircraft

    DOE Patents [OSTI]

    Bennett, Charles L. (Livermore, CA)

    2007-09-18T23:59:59.000Z

    A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  5. Tunable thermal link

    DOE Patents [OSTI]

    Chang, Chih-Wei; Majumdar, Arunava; Zettl, Alexander K.

    2014-07-15T23:59:59.000Z

    Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.

  6. Thermal Recovery Methods

    SciTech Connect (OSTI)

    White, P.D.; Moss, J.T.

    1983-01-01T23:59:59.000Z

    Thermal Recovery Methods describes the basic concepts of thermal recovery and explains the injection patterns used to exploit reservoir conditions. Basic reservoir engineering is reviewed with an emphasis on changes in flow characteristics caused by temperature. The authors discuss an energy balance for steam and combustion drive, and they explain in situ reactions. Heat loss, combustion drive, and steam displacement also are examined in detail, as well as cyclic steam injection, downhole ignition, well heating, and low-temperature oxidation. Contents: Thermal processes; Formation and reservoir evaluations; Well patterns and spacing; Flow and process equations; Laboratory simulation of thermal recovery; Heat loss and transmission; Displacement and production; Equipment; Basic data for field selection; Laboratory evaluation of combustion characteristics; Thermal properties of reservoirs and fluids.

  7. Thermal treatment wall

    DOE Patents [OSTI]

    Aines, Roger D. (Livermore, CA); Newmark, Robin L. (Livermore, CA); Knauss, Kevin G. (Livermore, CA)

    2000-01-01T23:59:59.000Z

    A thermal treatment wall emplaced to perform in-situ destruction of contaminants in groundwater. Thermal destruction of specific contaminants occurs by hydrous pyrolysis/oxidation at temperatures achievable by existing thermal remediation techniques (electrical heating or steam injection) in the presence of oxygen or soil mineral oxidants, such as MnO.sub.2. The thermal treatment wall can be installed in a variety of configurations depending on the specific objectives, and can be used for groundwater cleanup, wherein in-situ destruction of contaminants is carried out rather than extracting contaminated fluids to the surface, where they are to be cleaned. In addition, the thermal treatment wall can be used for both plume interdiction and near-wellhead in-situ groundwater treatment. Thus, this technique can be utilized for a variety of groundwater contamination problems.

  8. Microsecond switchable thermal antenna

    SciTech Connect (OSTI)

    Ben-Abdallah, Philippe, E-mail: pba@institutoptique.fr; Benisty, Henri; Besbes, Mondher [Laboratoire Charles Fabry, UMR 8501, Institut d'Optique, CNRS, Université Paris-Sud 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex (France)

    2014-07-21T23:59:59.000Z

    We propose a thermal antenna that can be actively switched on and off at the microsecond scale by means of a phase transition of a metal-insulator material, the vanadium dioxide (VO{sub 2}). This thermal source is made of a periodically patterned tunable VO{sub 2} nanolayer, which support a surface phonon-polariton in the infrared range in their crystalline phase. Using electrodes properly registered with respect to the pattern, the VO{sub 2} phase transition can be locally triggered by ohmic heating so that the surface phonon-polariton can be diffracted by the induced grating, producing a highly directional thermal emission. Conversely, when heating less, the VO{sub 2} layers cool down below the transition temperature, the surface phonon-polariton cannot be diffracted anymore so that thermal emission is inhibited. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.

  9. Multi-rhythmicity in an optoelectronic oscillator with large delay

    E-Print Network [OSTI]

    Weicker, Lionel; Rosin, David P; Gauthier, Daniel J

    2014-01-01T23:59:59.000Z

    An optoelectronic oscillator exhibiting a large delay in its feedback loop is studied both experimentally and theoretically. We show that multiple square-wave oscillations may coexist for the same values of the parameters (multi-rhythmicity). Depending on the sign of the phase shift, these regimes admit either periods close to an integer fraction of the delay or periods close to an odd integer fraction of twice the delay. These periodic solutions emerge from successive Hopf bifurcation points and stabilize at a finite amplitude following a scenario similar to Eckhaus instability in spatially extended systems. We find quantitative agreements between experiments and numerical simulations. The linear stability of the square-waves is substantiated analytically by determining stable fixed points of a map.

  10. Pulsed Photofission Delayed Gamma Ray Detection for Nuclear Material Identification

    SciTech Connect (OSTI)

    John Kavouras; Xianfei Wen; Daren R. Norman; Dante R. Nakazawa; Haori Yang

    2012-11-01T23:59:59.000Z

    Innovative systems with increased sensitivity and resolution are in great demand to detect diversion and to prevent misuse in support of nuclear materials management for the U.S. fuel cycle. Nuclear fission is the most important multiplicative process involved in non-destructive active interrogation. This process produces the most easily recognizable signature for nuclear materials. High-energy gamma rays can also excite a nucleus and cause fission through a process known as photofission. After photofission reactions, delayed signals are easily distinguishable from the interrogating radiation. Linac-based, advanced inspection techniques utilizing the fission signals after photofission have been extensively studied for homeland security applications. Previous research also showed that a unique delayed gamma ray energy spectrum exists for each fissionable isotope. Isotopic composition measurement methods based on delayed gamma ray spectroscopy will be the primary focus of this work.

  11. Growth of geologic fractures into large-strain populations: review of nomenclature, subcritical crack growth, and some implications

    E-Print Network [OSTI]

    Growth of geologic fractures into large-strain populations: review of nomenclature, subcritical at the earliest stages of fracture nucleation). Slow, subcritical crack growth in rock is associated

  12. Thermal decomposition of charring materials

    SciTech Connect (OSTI)

    Nurbakhsh, S.

    1989-01-01T23:59:59.000Z

    Experimental techniques and methods were developed to investigate the transient process of wood pyrolysis under different levels of external radiation, moisture content of the wood sample, and oxygen concentration of the ambient atmosphere. A unique small-scale combustion-wind tunnel was constructed to conduct the pyrolysis experiments and to obtain the time dependent gasification mass flux, surface and in-depth temperatures, and evolved products of pyrolysis (CO, CO{sub 2}, H{sub 2}O, and total hydrocarbons (THC)) for thermally thick samples of Douglas-fir. Experiments were performed both in inert atmosphere (nitrogen), and in air at several different heat fluxes and three different moisture contents of wood. Time dependent empirical chemical composition, char yield, and the heat of combustion of the pyrolysis products were determined. The experimental results indicate that the presence of moisture reduces the pyrolysis mass flux and delays the occurrence of its maxima. Presence of oxygen drastically increases the pyrolysis mass flux but its effect specially at lower temperatures depends on the experimental conditions such as the boundary layer thickness over the wood surface. Char yield, chemical composition of the volatiles, and the heat of combustion were found to vary during the pyrolysis process and with changes in the environmental conditions and wood moisture content. The pyrolysis temperature assumption often used for the simplified modeling of wood pyrolysis was examined in detail by considering two otherwise identical models; one with infinitely fast decomposition kinetics and the other with finite rate chemistry. It was concluded that the pyrolysis temperature is not a material property and different pyrolysis temperatures are needed for every problem.

  13. Delayed pulsar kicks from the emission of sterile neutrinos

    SciTech Connect (OSTI)

    Kusenko, Alexander; Mandal, Bhabani Prasad; Mukherjee, Alok [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Department of Physics, Banaras Hindu University, Varanasi-221005 (India)

    2008-06-15T23:59:59.000Z

    The observed velocities of pulsars suggest the possibility that sterile neutrinos with mass of several keV are emitted from a cooling neutron star. The same sterile neutrinos could constitute all or part of cosmological dark matter. The neutrino-driven kicks can exhibit delays depending on the mass and the mixing angle, which can be compared with the pulsar data. We discuss the allowed ranges of sterile neutrino parameters, consistent with the latest cosmological and x-ray bounds, which can explain the pulsar kicks for different delay times.

  14. Time delayed laser networks: phase versus chaos synchronization

    E-Print Network [OSTI]

    Reidler, I; Aviad, Y; Guberman, S; Friesem, A A; Rosenbluh, M; Davidson, N; Kanter, I

    2013-01-01T23:59:59.000Z

    The synchronization of chaotic lasers and the optical phase synchronization of light originating in multiple coupled lasers have both been extensively studied, however, the interplay between these two phenomena, especially at the network level is unexplored. Here we experimentally compare chaos synchronization of laser networks with heterogeneous coupling delay times to phase synchronization of similar networks. While chaotic lasers exhibit deterioration in synchronization as the network time delay heterogeneity increases, phase synchronization is found to be independent of heterogeneity. The experimental results are found to be in agreement with numerical simulations for semiconductor lasers.

  15. Time delayed laser networks: phase versus chaos synchronization

    E-Print Network [OSTI]

    I. Reidler; M. Nixon; Y. Aviad; S. Guberman; A. A. Friesem; M. Rosenbluh; N. Davidson; I. Kanter

    2013-04-03T23:59:59.000Z

    The synchronization of chaotic lasers and the optical phase synchronization of light originating in multiple coupled lasers have both been extensively studied, however, the interplay between these two phenomena, especially at the network level is unexplored. Here we experimentally compare chaos synchronization of laser networks with heterogeneous coupling delay times to phase synchronization of similar networks. While chaotic lasers exhibit deterioration in synchronization as the network time delay heterogeneity increases, phase synchronization is found to be independent of heterogeneity. The experimental results are found to be in agreement with numerical simulations for semiconductor lasers.

  16. High-Temperature Thermal Array for Next Generation Solar Thermal...

    Broader source: Energy.gov (indexed) [DOE]

    Thermal Array for Next Generation Solar Thermal Power Production Award Number: DE-EE00025828 Report Date: March 15, 2013 PI: Stephen Obrey * Technical approach is focused on...

  17. The effect of residuals on the presence of intergranular surface cracks on continuously cast billets

    SciTech Connect (OSTI)

    Wijngaarden, M.J.U.T. van; Visagie, G.P.

    1996-12-31T23:59:59.000Z

    During 1991, Iscor Vereeniging experienced a dramatic increase in the rejection rate of specialty steel bars rolled from continuously cast billets due to the presence of seams on the bars. The seams originated from tearing of the billets during the first 2 passes in the roughing mill during hot rolling. The defective billets were found to contain fine intergranular cracks on the surface. Such cracks have been described in the literature and have been attributed to the presence of high levels of residuals resulting in the well-known phenomenon of surface hot shortness which results from the enrichment of residuals at the grain boundaries after preferential oxidation of iron during scaling of the steel. The present investigation revealed that the effect of residuals on intergranular surface cracking is a complex interaction between steel composition and casting conditions such as casting speed, intensity of secondary cooling, section size, and mold type. This paper quantifies the effect of residuals on the intergranular surface cracking of continuously cast billets and quantitatively relates the incidence of these cracks to parameters which can be controlled during steelmaking and continuous casting.

  18. Belgian approach to steam generator tube plugging for primary water stress corrosion cracking

    SciTech Connect (OSTI)

    Frederick, G. (TRACTEBEL, Brussels (Belgium)); Hernalsteen, P.; Dobbeni, D. (Laboratoire Belge de l'Industrie Electrique (LABORELEC), Linkebeek (Belgium))

    1990-03-01T23:59:59.000Z

    For a number of years, three Belgian nuclear power plants have experienced primary water stress corrosion cracking (PWSCC) in the expansion transition area on a very large number of tubes. One of the plants has part depth rolled tubes and the others have full depth expansion. The report presents a review of the leakage experience associated with (PWSCC) in the Doel 2, Doel 3 and Tihange 2 Nuclear Power Plants and illustrates the type of cracking observed on pulled tubes from Doel 2 and Doel 3. The Belgian units operate with numerous through wall cracks without impairing the safety and the reliability of the plants. This is achieved by a safety approach based on the extensive use of advanced non-destructive examination (NDE) techniques and the development of new plugging limits. These limits are derived from a realistic interpretation of NRC Regulatory Guide 1.121 and are backed up by a substantial experimental program. The report summarizes the establishment of plugging limits for both axial and circumferential cracks in the roll transition area of full depth rolled tubes. The LABORELEC eddy current rotating probe (RPC) technology and associated crack sizing methodology are also described. 8 refs., 2 figs., 1 tab.

  19. Cracking of simulated oil refinery off-gas over a coal char, petroleum coke, and quartz

    SciTech Connect (OSTI)

    Yuan Zhang; Jin-hu Wu; Dong-ke Zhang [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

    2008-03-15T23:59:59.000Z

    The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only over the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.

  20. Materials Science and Engineering A 490 (2008) 2635 Mechanisms of cracking and delamination within thick thermal barrier

    E-Print Network [OSTI]

    Hutchinson, John W.

    and sub-surface delaminations, as well as spalls. Estimates of the residual stress gradients made on cross limited by deposits of calcium-magnesium-alumino-silicate (CMAS) [1­3]. These deposits melt and wet with a TBC generated by electron beam physical vapor deposition (EB-PVD) [2]. That assessment ascertained

  1. Multilayer thermal barrier coating systems

    DOE Patents [OSTI]

    Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

    2000-01-01T23:59:59.000Z

    The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

  2. Solar Thermal Conversion

    SciTech Connect (OSTI)

    Kreith, F.; Meyer, R. T.

    1982-11-01T23:59:59.000Z

    The thermal conversion process of solar energy is based on well-known phenomena of heat transfer (Kreith 1976). In all thermal conversion processes, solar radiation is absorbed at the surface of a receiver, which contains or is in contact with flow passages through which a working fluid passes. As the receiver heats up, heat is transferred to the working fluid which may be air, water, oil, or a molten salt. The upper temperature that can be achieved in solar thermal conversion depends on the insolation, the degree to which the sunlight is concentrated, and the measures taken to reduce heat losses from the working fluid.

  3. Thermal insulations using vacuum panels

    DOE Patents [OSTI]

    Glicksman, Leon R. (Lynnfield, MA); Burke, Melissa S. (Pittsburgh, PA)

    1991-07-16T23:59:59.000Z

    Thermal insulation vacuum panels are formed of an inner core of compressed low thermal conductivity powders enclosed by a ceramic/glass envelope evaluated to a low pressure.

  4. A DELAYED NONLINEAR PBPK MODEL FOR GENISTEIN DOSIMETRY IN RATS

    E-Print Network [OSTI]

    A DELAYED NONLINEAR PBPK MODEL FOR GENISTEIN DOSIMETRY IN RATS #3; MICHAEL G. ZAGER y , HIEN T on laboratory animals and human volunteers [4], and critical literature reviews [32]. Phytoestrogens, a class endocrine-related e#11;ects such as reduced birth weight in rats and humans. In its conjugated form

  5. Kalman filter analysis of delayed neutron nondestructive assay measurements.

    SciTech Connect (OSTI)

    Aumeier, S. E.

    1998-04-29T23:59:59.000Z

    The ability to nondestructively determine the presence and quantity of fissile and fertile nuclei in various matrices is important in several nuclear applications including international and domestics safeguards, radioactive waste characterization and nuclear facility operations. Material irradiation followed by delayed neutron counting is a well known and useful nondestructive assay technique used to determine the fissile-effective content of assay samples. Previous studies have demonstrated the feasibility of using Kalman filters to unfold individual isotopic contributions to delayed neutron measurements resulting from the assay of mixes of uranium and plutonium isotopes. However, the studies in question used simulated measurement data and idealized parameters. We present the results of the Kalman filter analysis of several measurements of U/Pu mixes taken using Argonne National Laboratory's delayed neutron nondestructive assay device. The results demonstrate the use of Kalman filters as a signal processing tool to determine the fissile and fertile isotopic content of an assay sample from the aggregate delayed neutron response following neutron irradiation.

  6. Electron-capture delayed fission properties of {sup 242}Es

    SciTech Connect (OSTI)

    Shaughnessy, D. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Chemistry Department, University of California, Berkeley, California 94720 (United States); Adams, J. L. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Gregorich, K. E. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Lane, M. R. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Laue, C. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Lee, D. M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); McGrath, C. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Patin, J. B. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Strellis, D. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Sylwester, E. R. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Chemistry Department, University of California, Berkeley, California 94720 (United States)] (and others)

    2000-04-01T23:59:59.000Z

    Electron-capture delayed fission of {sup 242}Es produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at 87 MeV (on target) was observed to decay with a half-life of 11{+-}3 s, consistent with the reported {alpha}-decay half-life of {sup 242}Es of 16{sub -4}{sup +6} s. The mass-yield distribution of the fission fragments is highly asymmetric. The average pre-neutron emission total kinetic energy of the fragments was measured to be 183{+-}18 MeV. Based on the ratio of the measured number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 242}Cf (100% {alpha} branch), the probability of delayed fission was determined to be 0.006{+-}0.002. This value for the delayed fission probability fits the experimental trend of increasing delayed fission probability with increasing Q value for electron capture. (c) 2000 The American Physical Society.

  7. Delayed Gamma-Ray Spectroscopy for Spent Nuclear Fuel Assay

    SciTech Connect (OSTI)

    Campbell, Luke W.; Hunt, Alan W.; Ludewigt, Bernhard A.; Mozin, Vladimir V.

    2012-04-01T23:59:59.000Z

    High-energy, beta-delayed gamma-ray spectroscopy is investigated as a non-destructive assay technique for the determination of plutonium mass in spent nuclear fuel. This approach exploits the unique isotope-specific signatures contained in the delayed gamma-ray emission spectra detected following active interrogation with an external neutron source. A high fidelity modeling approach is described that couples radiation transport, analytical decay/depletion, and a newly developed gamma-ray emission source reconstruction code. Initially simulated and analyzed was a “one-pass” delayed gamma-ray assay that focused on the long-lived signatures. Also presented are the results of an independent study that investigated “pulsed mode” measurements, to capture the more isotope-specific, short-lived signatures. Initial modeling results outlined in this paper suggest that delayed gamma-ray assay of spent nuclear fuel assemblies can be accomplished with a neutron generator of sufficient strength and currently available gamma-ray detectors.

  8. Ultra LowVoltage Delay Locked Loop Using Carbon Nanotubes

    E-Print Network [OSTI]

    Ayers, Joseph

    Ultra LowVoltage Delay Locked Loop Using Carbon Nanotubes J.S. Ajit Northeastern University Dept, MA 02115 E-mail: ybk@ece.neu.edu AbstractCarbon Nanotube FET technology is investigated for both the shrinking process to continue, and for the development of novel architectures, is the carbon

  9. Dynamics of connected vehicle systems with delayed acceleration feedback

    E-Print Network [OSTI]

    Daly, Samantha

    predecessor is measured by radar and the vehicle is actuated accordingly. Since the delay in these systems conclusions are verified by simulations at the nonlinear level. Ã? 2014 Elsevier Ltd. All rights reserved. 1 limited ability to change the dynamics at the system level, which is necessary if one wishes to eliminate

  10. MANAGING WIRE DELAY IN CHIP MULTIPROCESSOR CACHES Bradford M. Beckmann

    E-Print Network [OSTI]

    Wood, David A.

    . In contrast, transmission lines can reduce on-chip wire delay by an order of magnitude versus conventional wires and provide low latency to all shared cache banks. We demonstrate on-chip transmission lines provided by transmission lines and reduce off-chip misses versus a design using conventional wires. We

  11. Extending Qualitative Modelling for Simulation of TimeDelayed Behaviour

    E-Print Network [OSTI]

    Miguel, Ian

    industrial plants is to choose a measured variable and maintain the re­ quired value of this variable through a process of mea­ surement, comparison, and adjustment. A time delay between a disturbance in the plant applicable to simulators that enable synchronous tracking. The rest of this paper is arranged as follows

  12. Delay analysis of bursty tasks using workload arrival functions

    E-Print Network [OSTI]

    Kim, Junwhan

    2001-01-01T23:59:59.000Z

    and the integrated methodologies with variable workloads are introduced. However, these methodologies have some limitations when they are applied to task systems instead of traffic. In this thesis, we propose that the end-to-end delay computed by the decomposed...

  13. Task Assignment in a Server Farm with Switching Delays and

    E-Print Network [OSTI]

    Hyytiä, Esa

    costs Holding costs (per job) Objective to balance between Energy consumption Performance (e.g., latency Energy- and Delay-aware cost structure Switching costs Running costs Holding costs (per job) Objective to balance between Energy consumption Performance (e.g., latency) Heterogeneous servers, job-specific costs

  14. Efficient Path Delay Test Generation with Boolean Satisfiability

    E-Print Network [OSTI]

    Bian, Kun

    2013-12-10T23:59:59.000Z

    delay test generator CodGen. A mixed structural-functional approach was implemented in CodGen where longest paths were detected using the K Longest Path Per Gate (KLPG) algorithm and path justification and dynamic compaction were handled with the SAT...

  15. Practical delay modeling of externally recirculated burned gas fraction for

    E-Print Network [OSTI]

    stringent norms on fuel consumption and pollutant emissions for automotive engines have substantially- setts Avenue, Cambridge MA 02139, USA e-mail: dbp@mit.edu Thomas Leroy and Jonathan Chauvin IFP Energies a significant delay trans- port which should be taken into account to accurately estimate and control the (dis

  16. Fast amplitude and delay measurement for characterization of optical devices

    E-Print Network [OSTI]

    Thompson, Michael Thomas

    2006-10-30T23:59:59.000Z

    to determine the chromatic dispersion in the device under test by taking the derivative of the group delay with respect to optical wavelength. The measurement setup allows both step-tunable and sweeping laser sources. A modulation frequency of up to 2.7 GHz...

  17. Turbo King: Framework for Large-Scale Internet Delay Measurements

    E-Print Network [OSTI]

    Loguinov, Dmitri

    servers (which is called cache pollution) and requires large traffic overhead when deployed in large consuming half the bandwidth needed by King and reducing the impact of cache pollution by several orders building an all-to-all delay matrix between approximately 220, 000 BGP prefixes advertised in the Internet

  18. Task 3.9 -- Catalytic tar cracking. Semi-annual report, January 1--June 30, 1995

    SciTech Connect (OSTI)

    Young, B.C.; Timpe, R.C.

    1995-12-31T23:59:59.000Z

    Tar produced in the gasification of coal is deleterious to the operation of downstream equipment including fuel cells, gas turbines, hot-gas stream cleanup filters, and pressure swing adsorption systems. Catalytic cracking of tars to smaller hydrocarbons can be an effective means to remove these tars from gas streams and, in the process, generate useful products, e.g., methane gas, which is crucial to the operation of molten carbonate fuel cells. The objectives of this project are to investigate whether gasification tars can be cracked by synthetic nickel-substituted micamontmorillonite, zeolite, or dolomite material; and whether the tars can be cracked selectively by these catalysts to produce a desired liquid and/or gas stream. Results to date are presented in the cited papers.

  19. ISO test method to determine sustained-load-cracking resistance of aluminium cylinders

    SciTech Connect (OSTI)

    Bhuyan, G.S. [Powertech Labs. Inc., Surrey, British Columbia (Canada); Rana, M.D. [Praxair, Inc., Tonawanda, NY (United States)

    1999-08-01T23:59:59.000Z

    Leak as well as rupture types of failures related to sustained-load-cracking (SLC) have been observed in high-pressure gas cylinders fabricated from certain aluminium alloy. The stable crack growth mechanism observed primarily in the cylinder neck and shoulder area have been identified as the SLC mechanism occurring at room temperature without any environmental effect. The International Organization for standardization (ISO) Sub-Committee 3, Working Group 16 has developed a test method to measure the SLC resistance using fracture mechanics specimens along with an acceptance criterion for aluminium cylinders. The technical rationale for the proposed test method and the physical significance of the acceptance criterion to the cylinder performance in terms of critical stress-crack size relationship is presented. Application of the developed test method for characterizing new aluminium alloy for manufacturing cylinders is demonstrated. SLC characteristics of several aluminium cylinders as well as on-board cylinders for natural gas vehicles assessed by the authors are discussed.

  20. Progressive flow cracking of coal/oil mixtures with high metals content catalyst

    SciTech Connect (OSTI)

    Zandona, O.J.

    1989-10-10T23:59:59.000Z

    This patent describes a process for economically producing liquid fuel products at least partly from coal. It comprises: introducing a progressive flow catalytic cracking zone a charge stock comprising a pumpable mixture of solid, particulate coal and carbo-metallic oil and forming within the zone a stream having a linear velocity of at least about 25 feet per second. The stream comprising the charge stock and a hydrocarbon zeolite cracking catalyst promoting dehydrogenation of the charge stock; forming mobile hydrogen within the zone by the dehydrogenation; introducing the mobile hydrogen into the stream by dehydrogenation of the charge stock in the absence of added molecular hydrogen, thereby producing liquid products from the charge stock while laying down coke on the hydrocarbon cracking catalyst in the range of about 0.3% to about 3% and thereby producing spent catalyst; separating from the spent catalyst the liquid products.

  1. Method and apparatus for detecting external cracks from within a metal tube

    DOE Patents [OSTI]

    Caffey, Thurlow W. H. (Albuquerque, NM)

    2001-08-07T23:59:59.000Z

    A method and tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is described for the detection of external sidewall cracks and other anomalies in boiler tubes and other enclosures. The invention utilizes the concept of radar backscatter rather than eddy-currents or ultrasound, which are sometimes used in prior art crack-detection methods. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to -40 dB in thin-walled boiler tubes.

  2. Ultrasonic inspection of austenitic stainless steel welds with artificially produced stress corrosion cracks

    SciTech Connect (OSTI)

    Dugan, Sandra; Wagner, Sabine [Materials Testing Institute University of Stuttgart (MPA), Pfaffenwaldring 32, 70569 Stuttgart (Germany)

    2014-02-18T23:59:59.000Z

    Austenitic stainless steel welds and nickel alloy welds, which are widely used in nuclear power plants, present major challenges for ultrasonic inspection due to the grain structure in the weld. Large grains in combination with the elastic anisotropy of the material lead to increased scattering and affect sound wave propagation in the weld. This results in a reduced signal-to-noise ratio, and complicates the interpretation of signals and the localization of defects. Mechanized ultrasonic inspection was applied to study austenitic stainless steel test blocks with different types of flaws, including inter-granular stress corrosion cracks (IGSCC). The results show that cracks located in the heat affected zone of the weld are easily detected when inspection from both sides of the weld is possible. In cases of limited accessibility, when ultrasonic inspection can be carried out only from one side of a weld, it may be difficult to distinguish between signals from scattering in the weld and signals from cracks.

  3. Mode III interfacial crack in the presence of couple stress elastic materials

    E-Print Network [OSTI]

    Andrea Piccolroaz; Gennady Mishuris; Enrico Radi

    2011-04-02T23:59:59.000Z

    In this paper we are concerned with the problem of a crack lying at the interface between dissimilar materials with microstructure undergoing antiplane deformations. The micropolar behaviour of the materials is described by the theory of couple stress elasticity developed by Koiter (1964). This constitutive model includes the characteristic lengths in bending and torsion and thus it is able to account for the underlying microstructure of the two materials. We perform an asymptotic analysis to investigate the behaviour of the solution near the crack tip. It turns out that the stress singularity at the crack tip is strongly influenced by the microstructural parameters and it may or may not show oscillatory behaviour depending on the ratio between the characteristic lengths.

  4. Evaluation of cracking in the 241-AZ tank farm ventilation line at the Hanford Site

    SciTech Connect (OSTI)

    ANANTATMULA, R.P.

    1999-10-20T23:59:59.000Z

    In the period from April to October of 1988, a series of welding operations on the outside of the AZ Tank Farm ventilation line piping at the Hanford Site produced unexpected and repeated cracking of the austenitic stainless steel base metal and of a seam weld in the pipe. The ventilation line is fabricated from type 304L stainless steel pipe of 24 inch diameter and 0.25 inch wall thickness. The pipe was wrapped in polyethylene bubble wrap and buried approximately 12 feet below grade. Except for the time period between 1980 and 1987, impressed current cathodic protection has been applied to the pipe since its installation in 1974. The paper describes the history of the cracking of the pipe, the probable cracking mechanisms, and the recommended future action for repair/replacement of the pipe.

  5. Method for cracking hydrocarbon compositions using a submerged reactive plasma system

    DOE Patents [OSTI]

    Kong, P.C.

    1997-05-06T23:59:59.000Z

    A method is described for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap there between. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition. 6 figs.

  6. Method for cracking hydrocarbon compositions using a submerged reactive plasma system

    DOE Patents [OSTI]

    Kong, Peter C. (Idaho Falls, ID)

    1997-01-01T23:59:59.000Z

    A method for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap therebetween. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition.

  7. Manipulation of Thermal Phonons

    E-Print Network [OSTI]

    Hsu, Chung-Hao

    2013-03-28T23:59:59.000Z

    to manipulate the behavior of phonons is crucial for both energy applications and the cooling of integrated circuits. A novel class of artificially periodic structured materials — phononic crystals — might make manipulation of thermal phonons possible. In many...

  8. Thermally Polymerized Rylene Nanoparticles

    E-Print Network [OSTI]

    Andrew, Trisha Lionel

    Rylene dyes functionalized with varying numbers of phenyl trifluorovinyl ether (TFVE) moieties were subjected to a thermal emulsion polymerization to yield shape-persistent, water-soluble chromophore nanoparticles. Perylene ...

  9. Thermal Insulation Systems

    E-Print Network [OSTI]

    Stanley, T. F.

    1982-01-01T23:59:59.000Z

    Thermal insulation systems are receiving a high degree of attention in view of increasing energy cost. Industrial, commercial and residential energy users are all well aware of energy cost increases and great emphasis is being directed to energy...

  10. Thermally driven circulation

    E-Print Network [OSTI]

    Nelken, Haim

    1987-01-01T23:59:59.000Z

    Several problems connected by the theme of thermal forcing are addressed herein. The main topic is the stratification and flow field resulting from imposing a specified heat flux on a fluid that is otherwise confined to a ...

  11. Contact thermal lithography

    E-Print Network [OSTI]

    Schmidt, Aaron Jerome, 1979-

    2004-01-01T23:59:59.000Z

    Contact thermal lithography is a method for fabricating microscale patterns using heat transfer. In contrast to photolithography, where the minimum achievable feature size is proportional to the wavelength of light used ...

  12. Photovoltaic-thermal collectors

    DOE Patents [OSTI]

    Cox, III, Charles H. (Carlisle, MA)

    1984-04-24T23:59:59.000Z

    A photovoltaic-thermal solar cell including a semiconductor body having antireflective top and bottom surfaces and coated on each said surface with a patterned electrode covering less than 10% of the surface area. A thermal-absorbing surface is spaced apart from the bottom surface of the semiconductor and a heat-exchange fluid is passed between the bottom surface and the heat-absorbing surface.

  13. Dynamic modelling for thermal micro-actuators using thermal networks

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Dynamic modelling for thermal micro-actuators using thermal networks Beatriz L´opez-Wallea,1 and analytical calculations. Key words: Micro-actuators, Thermal modelling, Electrical analogy, Thermal network 1 and MicroMechatronic Systems Department (AS2M), 24 rue Alain Savary, 25000 Besan¸con, France Abstract

  14. A study of microstrip delay lines on high dielectric constant substrates

    E-Print Network [OSTI]

    Ashour, Thomas Joseph

    1996-01-01T23:59:59.000Z

    . . . . 83 VII. B. Conclusions. . . . . REFERENCES . . VITA . . . . 87 LIST OF FIGURES FIGURE Page 1 A 578ps delay line on CB material 2 A 1, 200 ps spiral delay line on duroid. . 19 3 274 ps delay lines on duroid with thickness, h, of (a) 10 mils... and (b) 5 mila. . . . 20 4 S-parameter data of 274 ps delay lines having h of (a)10 mils and (b) 5 mils. . . 22 5 Microstrip delay line test setup. . . 25 6 Top and side view of test fixture, launchers, and delay circuit. . . . . . . . . . 25 7 The (a...

  15. Crack detection on HC-130H aircraft using low frequency eddy current

    SciTech Connect (OSTI)

    Moore, D.G. [Sandia National Labs., Albuquerque, NM (United States); Mihelic, J.E.; Barnes, J.D. [Coast Guard, Elizabeth City, NC (United States). Aircraft Repair and Supply Center

    1998-02-01T23:59:59.000Z

    An eddy current inspection method was developed at the Federal Aviation Administration`s Airworthiness Assurance NDI Validation Center (AANC) to easily and rapidly detect subsurface fatigue cracks in the wheel well fairing on the US Coast Guard (USCG) HC-130H aircraft caused by fatigue. The inspection procedure locates cracks as small as 10.2 millimeters in length at 2.54 mm below the skin surface at raised fastener sites. The test procedure developed baseline three USCG aircraft. Inspection results on the three aircraft reveals good correlation with results made during subsequent structural disassembly.

  16. Carbon fiber composite characterization in adverse thermal environments.

    SciTech Connect (OSTI)

    Gomez-Vasquez, Sylvia; Brown, Alexander L.; Hubbard, Joshua A.; Ramirez, Ciro J.; Dodd, Amanda B.

    2011-05-01T23:59:59.000Z

    The behavior of carbon fiber aircraft composites was studied in adverse thermal environments. The effects of resin composition and fiber orientation were measured in two test configurations: 102 by 127 millimeter (mm) test coupons were irradiated at approximately 22.5 kW/m{sup 2} to measure thermal response, and 102 by 254 mm test coupons were irradiated at approximately 30.7 kW/m{sup 2} to characterize piloted flame spread in the vertically upward direction. Carbon-fiber composite materials with epoxy and bismaleimide resins, and uni-directional and woven fiber orientations, were tested. Bismaleimide samples produced less smoke, and were more resistant to flame spread, as expected for high temperature thermoset resins with characteristically lower heat release rates. All materials lost approximately 20-25% of their mass regardless of resin type, fiber orientation, or test configuration. Woven fiber composites displayed localized smoke jetting whereas uni-directional composites developed cracks parallel to the fibers from which smoke and flames emanated. Swelling and delamination were observed with volumetric expansion on the order of 100% to 200%. The purpose of this work was to provide validation data for SNL's foundational thermal and combustion modeling capabilities.

  17. An experimental study on the effects of compressive stress on the fatigue crack growth of low-alloy steel

    SciTech Connect (OSTI)

    Jones, D.P.; Hoppe, R.G. [Westinghouse Electric Corp., West Mifflin, PA (United States). Bettis Atomic Power Lab.; Hechmer, J.L. [Babcock and Wilcox Co., Barberton, OH (United States); James, B.A. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgy

    1993-12-01T23:59:59.000Z

    A series of fatigue crack growth rate tests was conducted in order to study effects of negative stress ratio on fatigue crack growth rate of low-alloy steel in air. Four-point bend specimens were used to simulate linear stress distributions typical of pressure vessel applications. This type of testing adds to knowledge on negative stress ratio effects for low-alloy steels obtained in the past from uniform tension-compression tests. Applied bending stress range was varied over twice the yield strength. Load control was used for tests for which the stress range was less than twice the yield strength and deflection control was used for the higher stress range tests. Crack geometries were both short and long fatigue cracks started at notches and tight fatigue cracks for which crack closure could occur over the full crack face. Results are presented in terms of the stress intensity factor ratio R = K{sub MIN}/K{sub MAX}. The negative R-ratio test results were correlated to an equation of the form da/dN = C[{Delta}K/(A-R)]{sup n}, where A, C, and n are curve fitting parameters. It was found that effects of negative R-ratio on fatigue crack growth rates for even the high stress range tests could be bounded by correlating the above equation to only positive R-ratio test results and extending the resulting equation into the negative R-ratio regime.

  18. Applying diffuse ultrasound under dynamic loading to improve closed crack characterization in concrete , A. Quiviger1,2

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    in concrete C. Payan1 , A. Quiviger1,2 , V. Garnier1 , J.F. Chaix1 , J. Salin2 1 Aix Marseille Université studies show the ability of diffuse ultrasound to characterize surface breaking cracks in concrete the sensitivity of the method for various crack depths and highlight its potential for concrete nondestructive

  19. Micromechanisms of short fatigue crack growth in an Al-Si piston alloy. T.O. Mbuya1

    E-Print Network [OSTI]

    1 Micromechanisms of short fatigue crack growth in an Al-Si piston alloy. T.O. Mbuya1 , and P behaviour of a model cast aluminium piston alloy has been investigated. This has been achieved using. Keywords: Fatigue; Short fatigue cracks; Fatigue micromechanics; Al-Si ; Fatigue ; piston alloys 1

  20. Diffusion and Catalytic Cracking of 1,3,5 Tri-iso-propyl-benzene in FCC Catalysts

    E-Print Network [OSTI]

    Al-Khattaf, Sulaiman

    1 Diffusion and Catalytic Cracking of 1,3,5 Tri-iso- propyl-benzene in FCC Catalysts S.Al-Khattaf1 describes catalytic cracking experiments developed in a novel CREC Riser Simulator using 1,3,5-Tri-iso

  1. Crack Propagation Fracture Toughness of Several Wood Species Elijah Wilson, Meisam Shir Mohammadi, and John A. Nairn

    E-Print Network [OSTI]

    Nairn, John A.

    1 Crack Propagation Fracture Toughness of Several Wood Species Elijah Wilson, Meisam Shir Mohammadi In materials with process zones, such as fiber bridging zones in wood, it is crucial to characterize fracture toughness as a function of crack growth, known as the material's R curve. Here, a new fracture testing

  2. IMAGING OF EARLY-STAGE CRACKING ON REAL-SIZE CONCRETE STRUCTURE FROM 4-POINTS BENDING TEST

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    IMAGING OF EARLY-STAGE CRACKING ON REAL-SIZE CONCRETE STRUCTURE FROM 4-POINTS BENDING TEST Yuxiang difficulty on complexes material such as concrete, which is in part due the use of coherent waves in a very the application of this new technique on a real-size 15 tons concrete structure for imaging early-stage cracking

  3. Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model and Computations

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model In this paper we present the development of the macroscopic model describing the hydro-mechanical coupling model in the micro-porous domain saturated by a fluid. In the crack/vug domain the Stokes equation

  4. Preliminary Simulations for Geometric Optimization of a High-Energy Delayed Gamma Spectrometer for Direct Assay of Pu in Spent Nuclear Fuel

    SciTech Connect (OSTI)

    Kulisek, Jonathan A.; Campbell, Luke W.; Rodriguez, Douglas C.

    2012-06-07T23:59:59.000Z

    High-energy, beta-delayed gamma-ray spectroscopy is under investigation as part of the Next Generation Safeguard Initiative effort to develop non-destructive assay instruments for plutonium mass quantification in spent nuclear fuel assemblies. Results obtained to date indicate that individual isotope-specific signatures contained in the delayed gamma-ray spectra can potentially be used to quantify the total fissile content and individual weight fractions of fissile and fertile nuclides present in spent fuel. Adequate assay precision for inventory analysis can be obtained using a neutron generator of sufficient strength and currently available detection technology. In an attempt to optimize the geometric configuration and material composition for a delayed gamma measurement on spent fuel, the current study applies MCNPX, a Monte Carlo radiation transport code, in order to obtain the best signal-to-noise ratio. Results are presented for optimizing the neutron spectrum tailoring material, geometries to maximize thermal or fast fissions from a given neutron source, and detector location to allow an acceptable delayed gamma-ray signal while achieving a reasonable detector lifetime while operating in a high-energy neutron field. This work is supported in part by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

  5. Reflective Cracking Study: First-level Report on HVS Testing on Section 591RF - 45 mm MAC15TR-GOverlay

    E-Print Network [OSTI]

    Jones, David; Wu, R.; Harvey, John T

    2008-01-01T23:59:59.000Z

    of the asphalt concrete layer. Testing was stopped when thetesting being performed to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete.concrete. It describes the results of the sixth HVS reflective cracking testing

  6. Article for thermal energy storage

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    2000-06-27T23:59:59.000Z

    A thermal energy storage composition is provided which is in the form of a gel. The composition includes a phase change material and silica particles, where the phase change material may comprise a linear alkyl hydrocarbon, water/urea, or water. The thermal energy storage composition has a high thermal conductivity, high thermal energy storage, and may be used in a variety of applications such as in thermal shipping containers and gel packs.

  7. Simulation and Experiment of Thermal Fatigue in the CPV Die Attach: Preprint

    SciTech Connect (OSTI)

    Bosco, N.; Silverman, T.; Kurtz, S.

    2012-05-01T23:59:59.000Z

    FEM simulation and accelerated thermal cycling have been performed for the CPV die attach. Trends in fatigue damage accumulation and equivalent test time are explored and found to be most sensitive to temperature ramp rate. Die attach crack growth is measured through cycling and found to be in excellent agreement with simulations of the inelastic strain energy accumulated. Simulations of an entire year of weather data provides for the relative ranking of fatigue damage between four cites as well as their equivalent accelerated test time.

  8. Scheduling algorithms for throughput maximization in time-varying networks with reconfiguration delays

    E-Print Network [OSTI]

    Celik, Guner Dincer

    2012-01-01T23:59:59.000Z

    We consider the control of possibly time-varying wireless networks under reconfiguration delays. Reconfiguration delay is the time it takes to switch network resources from one subset of nodes to another and it is a ...

  9. Environmentally assisted cracking in light water reactors. Semiannual report, April 1994--September 1994, Volume 19

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Gavenda, D.J. [and others

    1995-09-01T23:59:59.000Z

    This report summarizes work performed by Argonne National Laboratory (ANL) on fatigue and environmentally assisted cracking (EAC) in light water reactors from April to September 1994. Topics that have been investigated include (a) fatigue of carbon and low-alloy steel used in piping and reactor pressure vessels, (b) EAC of austenitic stainless steels (SSs) and Alloy 600, and (c) irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS. Fatigue tests have been conducted on A106-Gr B and A533-Gr B steels in oxygenated water to determine whether a slow strain rate applied during different portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Crack growth data were obtained on fracture-mechanics specimens of SSs and Alloy 600 to investigate EAC in simulated boiling water reactor (BWR) and pressurized water reactor environments at 289{degrees}C. The data were compared with predictions from crack growth correlations developed at ANL for SSs in water and from rates in air from Section XI of the ASME Code. Microchemical changes in high- and commercial-purity Type 304 SS specimens from control-blade absorber tubes and a control-blade sheath from operating BWRs were studied by Auger electron spectroscopy and scanning electron microscopy to determine whether trace impurity elements may contribute to IASCC of these materials.

  10. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    SciTech Connect (OSTI)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

    1996-12-01T23:59:59.000Z

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  11. Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking

    DOE Patents [OSTI]

    Steeves, Arthur F. (Schenectady, NY); Stewart, James C. (Loudonville, NY)

    1981-01-01T23:59:59.000Z

    A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

  12. Effect of matrix acidity on resid cracking activity of FCC catalysts

    SciTech Connect (OSTI)

    Alerasool, S.; Doolin, P.K.; Hoffman, J.F. [Ashland Petroleum Company, Ashland, KY (United States)

    1996-10-01T23:59:59.000Z

    The importance of matrix acid sites on the cracking of large resid molecules in heavy crude fractions is discussed. The challenge of measuring fresh matrix acidity was overcome by first destroying the zeolite by treating the catalyst with concentrated acid and then titrating the acid sites by thermogravimetry of pyridine. Due to differences in hydrothermal stability, the acidity of matrix in its fresh form did not correlate with the commercial resid cracking activity on an equilibrated catalyst. To overcome this drawback, the zeolite was destroyed by steaming at 870{degrees}C. Such severe treatment created a matrix that closely resembled that of the commercially equilibrated catalyst. Changes in the nature of acid sites were investigated by performing diffuse reflectance infrared spectroscopy (DRIFTS) measurements on fresh and steamed matrices. While Lewis acid sites were predominant on most fresh matrices, the population of Bronsted acid sites increased as a result of hydrothermal deactivation. The correlations between each type of acidity and commercial resid cracking are discussed. The incorporation of acid density, type, and stability into a comprehensive model is shown to be an important prerequisite for designing robust resid cracking catalysts.

  13. Modeling of crack tip high inertia zone in dynamic brittle fracture

    E-Print Network [OSTI]

    Karedla-Ravi, Shankar

    2007-09-17T23:59:59.000Z

    energy dissipation around the crack tip and is assumed to be a function of external energy per volume input into the system. Finite element analysis is performed on PMMA with constant velocity boundary conditions and mesh discretization based on the work...

  14. Elastic-Plastic Models for Stable Crack Growtht *James R. Rice

    E-Print Network [OSTI]

    Elastic-Plastic Models for Stable Crack Growtht by *James R. Rice Mareh 1973 'PCAbh ~ ~ e c.\\. (n do not fully recover their strain upon unloading. The idealized non-linear elastic (left) and rigid-plastic,. there is ~ strain concentration created at the cut-ahead tip in the rigid-plastic material and the deformation field

  15. Crack propagation induced heating in crystalline energetic materials W. Holmes,a)

    E-Print Network [OSTI]

    Fayer, Michael D.

    Crack propagation induced heating in crystalline energetic materials W. Holmes,a) R. S. Francis of the heating of molecular vibrations and the possible initiation of chemical reaction from heat dissipated that vibrational temperatures can reach 800 K in 55 ps and exceed 550 K for 1 ns after the initial heating

  16. The crystallography of fatigue crack initiation in Incoloy-908 and A-286 steel

    SciTech Connect (OSTI)

    Krenn, C.R. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States)

    1996-12-01T23:59:59.000Z

    Fatigue crack initiation in the austenitic Fe-Ni superalloys Incoloy-908 and A-286 is examined using local crystallographic orientation measurements. Results are consistent with sharp transgranular initiation and propagation occurring almost exclusively on {l_brace}111{r_brace} planes in Incoloy-908 but on a variety of low index planes in A-286. This difference is attributed to the influence of the semicoherent grain boundary {eta} phase in A-286. Initiation in each alloy occurred both intergranularly and transgranularly and was often associated with blocky surface oxide and carbide inclusions. Taylor factor and resolved shear stress and strain crack initiation hypotheses were tested, but despite an inconclusive suggestion of a minimum required {l_brace}111{r_brace} shear stress, none of the hypotheses were found to convincingly describe preferred initiation sites, even within the subsets of transgranular cracks apparently free from the influence of surface inclusions. Subsurface inclusions are thought to play a significant role in crack initiation. These materials have applications for use in structural conduit for high field superconducting magnets designed for fusion energy use.

  17. A micromechanical approach of crack-induced damage in orthotropic media : application to a

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    with experimental data available for a ceramic matrix composite (unidirectional SiC-SiC). Key words: Homogenization; Eshelby tensor; Anisotropy; Damage; Brittle materials; Ceramic Matrix Composites; Micromechanics; Cracks matrix composite Vincent MONCHIET a , Cosmin GRUESCU b , Oana CAZACU c , Djimedo KONDO d, a

  18. Title: Crack Diagnostics via Fourier Transform: Real and Imaginary Components vs. Power Spectral Density

    E-Print Network [OSTI]

    Giurgiutiu, Victor

    Title: Crack Diagnostics via Fourier Transform: Real and Imaginary Components vs. Power Spectral simultaneously the real and imaginary components of the Fourier transforms as diagnostics features approach consists of using new features based on the real and imaginary parts of the Fourier transform

  19. INTERFACE CRACK PROPAGATION IN POROUS AND TIME-DEPENDENT MATERIALS ANALYZED WITH

    E-Print Network [OSTI]

    Boyer, Edmond

    INTERFACE CRACK PROPAGATION IN POROUS AND TIME-DEPENDENT MATERIALS ANALYZED WITH DISCRETE MODELS and the FPZ. From the point of view of design of structures, e.g. reinforced concrete structures, this size size, size effects, creep, ageing, fracture, viscoelastic- ity, time effect, concrete failure, discrete

  20. Micro-meter Crack Response to Rock Blast Vibrations, Wind Gusts & Weather Effects

    E-Print Network [OSTI]

    Micro-meter Crack Response to Rock Blast Vibrations, Wind Gusts & Weather Effects C. H. Dowding,1 effects. These measurements substantiate the conservancy of the 12.5 mm/s (0.5 in./s) blasting vibration blasting. Measurements in this case study now extend weather effects to include wind. While it has been