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1

Hydrogen Induced Cracking of Drip Shield  

DOE Green Energy (OSTI)

One potential failure mechanism for titanium and its alloys under repository conditions is via the absorption of atomic hydrogen in the metal crystal lattice. The resulting decreased ductility and fracture toughness may lead to brittle mechanical fracture called hydrogen-induced cracking (HIC) or hydrogen embrittlement. For the current design of the engineered barrier without backfill, HIC may be a problem since the titanium drip shield can be galvanically coupled to rock bolts (or wire mesh), which may fall onto the drip shield, thereby creating conditions for hydrogen production by electrochemical reaction. The purpose of this scientific analysis and modeling activity is to evaluate whether the drip shield will fail by HIC or not under repository conditions within 10,000 years of emplacement. This Analysis and Model Report (AMR) addresses features, events, and processes related to hydrogen induced cracking of the drip shield. REV 00 of this AMR served as a feed to ''Waste Package Degradation Process Model Report'' and was developed in accordance with the activity section ''Hydrogen Induced Cracking of Drip Shield'' of the development plan entitled ''Analysis and Model Reports to Support Waste Package PMR'' (CRWMS M&O 1999a). This AMR, prepared according to ''Technical Work Plan for: Waste Package Materials Data Analyses and Modeling'' (BSC 2002), is to feed the License Application.

G. De

2003-02-24T23:59:59.000Z

2

Trace Detection of Metastable Helium Molecules in Superfluid Helium by Laser-Induced Fluorescence  

SciTech Connect

We describe an approach to detecting ionizing radiation that combines the special properties of superfluid helium with the sensitivity of quantum optics techniques. Ionization in liquid helium results in the copious production of metastable He{sub 2} molecules, which can be detected by laser-induced fluorescence. Each molecule can be probed many times using a cycling transition, resulting in the detection of individual molecules with high signal to noise. This technique could be used to detect neutrinos, weakly interacting massive particles, and ultracold neutrons, and to image superfluid flow in liquid {sup 4}He.

McKinsey, D. N.; Lippincott, W.H.; Nikkel, J.A.; Rellergert, W.G. [Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520 (United States)

2005-09-09T23:59:59.000Z

3

Hydrogen Induced Cracking Susceptibility of Titanium Alloys in ...  

Science Conference Proceedings (OSTI)

May 16, 2007 ... This report evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain ...

4

Helium-ion-induced release of hydrogen from graphite  

DOE Green Energy (OSTI)

The ion-induced release of hydrogen from AXF-5Q graphite was studied for 350-eV helium ions. The hydrogen was implanted into the graphite with a low energy (approx.200 eV) and to a high fluence. This achieved a thin (approx.10-nm), saturated near-surface region. The release of hydrogen was measured as a function of helium fluence. A model that includes ion-induced detrapping, retrapping, and surface recombination was used to analyze the experimental data. A value of (1.65 +- 0.2) x 10/sup -16/ cm/sup 2/ was obtained from the detrapping cross section, and a value of (0.5 to 4) x 10/sup -14/ cm/sup 4//atoms was obtained for the recombination coefficient. 11 refs., 4 figs.

Langley, R.A.

1987-01-01T23:59:59.000Z

5

Hydrogen-Induced Cracking of the Drip Shield  

DOE Green Energy (OSTI)

Hydrogen-induced cracking is characterized by the decreased ductility and fracture toughness of a material due to the absorption of atomic hydrogen in the metal crystal lattice. Corrosion is the source of hydrogen generation. For the current design of the engineered barrier without backfill, hydrogen-induced cracking may be a concern because the titanium drip shield can be galvanically coupled to rock bolts (or wire mesh), which may fall onto the drip shield, thereby creating conditions for hydrogen production by electrochemical reaction. The purpose of this report is to analyze whether the drip shield will fail by hydrogen-induced cracking under repository conditions within 10,000 years after emplacement. Hydrogen-induced cracking is a scenario of premature failure of the drip shield. This report develops a realistic model to assess the form of hydrogen-induced cracking degradation of the drip shield under the hydrogen-induced cracking. The scope of this work covers the evaluation of hydrogen absorbed due to general corrosion and galvanic coupling to less noble metals (e.g., Stainless Steel Type 316 and carbon steels) under the repository conditions during the 10,000-year regulatory period after emplacement and whether the absorbed hydrogen content will exceed the critical hydrogen concentration value, above which the hydrogen-induced cracking is assumed to occur. This report also provides the basis for excluding the features, events, and processes (FEPs) related to hydrogen-induced cracking of the drip shield with particular emphasis on FEP 2.1.03.04.OB, hydride cracking of drip shields (DTN: M00407SEPFEPLA.000 [DIRS 170760]). This report is prepared according to ''Technical Work Plan (TWP) for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 169944]).

F. Hua

2004-09-07T23:59:59.000Z

6

Hydrogen induced crack growth in Grade-12 titanium  

DOE Green Energy (OSTI)

Internal hydrogen induced crack growth rates were measured in Grade-12 titanium which is a candidate material for high-level nuclear waste containers. As-received and hydrogen charged samples (5 ppM to 330 ppM hydrogen) were used for slow crack growth measurements at constant loads using a Krak Gauge. The testing temperature ranged from room temperature to 148/sup 0/C. The crack growth kinetics under low to moderate loads are linear, but this linear rate is interrupted by discrete fast crack jump segments with parabolic or cubic type kinetics. These fast jump segments are thought to be associated with the passage of the crack front through the alpha-beta interface phase or with the initial loading sequence. By measuring striation spacings on the fracture surface, most crack growth rates observed are found to be in stage II. The striations are considered to be associated with hydride fracture. The crack path is either transgranular in the alpha phase or interfacial in the alpha phase adjacent to the beta phase. For transgranular growth, crack growth rates are constant and slower than those for interfacial growth which is associated with fast crack growth through a high hydrogen concentration region. Most stage II crack growth rates depend slightly on the stress intensity suggesting the contribution of plastic tearing process to stage II kinetics. The activation energies for crack growth are much lower than the activation energy of hydrogen diffusion through the alpha phase, implying that hydrogen is transported along dislocations, grain boundaries or interfaces. When the temperature is increased, the crack velocity first reaches a maximum and then decreases at higher temperatures. These temperature effects come from lower hydrogen concentration trapped at dislocations or from slower hydride nucleation kinetics, both at higher temperatures.

Ahn, T.M.; Lee, K.S.

1984-01-01T23:59:59.000Z

7

It's Elemental - The Element Helium  

NLE Websites -- All DOE Office Websites (Extended Search)

to the atmosphere through cracks in the crust. Helium is commercially recovered from natural gas deposits, mostly from Texas, Oklahoma and Kansas. Helium gas is used to inflate...

8

Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless  

NLE Websites -- All DOE Office Websites (Extended Search)

Environmentally Assisted Environmentally Assisted Cracking of Ni-Base Alloys Capabilities Materials Testing Environmentally Assisted Cracking (EAC) of Reactor Materials Corrosion Performance/Metal Dusting Overview Light Water Reactors Fatigue Testing of Carbon Steels and Low-Alloy Steels Environmentally Assisted Cracking of Ni-Base Alloys Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless Steels Steam Generator Tube Integrity Program Air Oxidation Kinetics for Zr-based Alloys Fossil Energy Fusion Energy Metal Dusting Publications List Irradiated Materials Steam Generator Tube Integrity Other Facilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Corrosion and Mechanics of Materials Light Water Reactors Bookmark and Share

9

The Helium Effect on Irradiation Induced Microstructures in CANDU ...  

Science Conference Proceedings (OSTI)

Effects of Water Radiolysis on Stellite-6 Corrosion: Dependence on pH and Temperature · Environmentally Assisted Cracking Susceptibility Assessment of AP ...

10

On Modeling Hydrogen-Induced Intergranular Cracking under ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well · Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...

11

Neutron-induced dpa, transmutations, gas production, and helium embrittlement of fusion materials  

E-Print Network (OSTI)

In a fusion reactor materials will be subjected to significant fluxes of high-energy neutrons. As well as causing radiation damage, the neutrons also initiate nuclear reactions leading to changes in the chemical composition of materials (transmutation). Many of these reactions produce gases, particularly helium, which cause additional swelling and embrittlement of materials. This paper investigates, using a combination of neutron-transport and inventory calculations, the variation in displacements per atom (dpa) and helium production levels as a function of position within the high flux regions of a recent conceptual model for the "next-step" fusion device DEMO. Subsequently, the gas production rates are used to provide revised estimates, based on new density-functional-theory results, for the critical component lifetimes associated with the helium-induced grain-boundary embrittlement of materials. The revised estimates give more optimistic projections for the lifetimes of materials in a fusion power plant co...

Gilbert, M R; Nguyen-Manh, D; Zheng, S; Packer, L W; Sublet, J -Ch

2013-01-01T23:59:59.000Z

12

Direct evidence of mismatching effect on H emission in laser-induced atmospheric helium gas plasma  

Science Conference Proceedings (OSTI)

A time-resolved orthogonal double pulse laser-induced breakdown spectroscopy (LIBS) with helium surrounding gas is developed for the explicit demonstration of time mismatch between the passage of fast moving impurity hydrogen atoms and the formation of thermal shock wave plasma generated by the relatively slow moving major host atoms of much greater masses ablated from the same sample. Although this so-called 'mismatching effect' has been consistently shown to be responsible for the gas pressure induced intensity diminution of hydrogen emission in a number of LIBS measurements using different ambient gases, its explicit demonstration has yet to be reported. The previously reported helium assisted excitation process has made possible the use of surrounding helium gas in our experimental set-up for showing that the ablated hydrogen atoms indeed move faster than the simultaneously ablated much heavier major host atoms as signaled by the earlier H emission in the helium plasma generated by a separate laser prior to the laser ablation. This conclusion is further substantiated by the observed dominant distribution of H atoms in the forward cone-shaped target plasma.

Zener Sukra Lie; Koo Hendrik Kurniawan [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); May On Tjia [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia); Rinda, Hedwig [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Suliyanti, Maria Margaretha [Research Center for Physics, Indonesia Institute of Sciences, Kawasan PUSPIPTEK, Serpong, Tangerang Selatan 15314, Banten (Indonesia); Syahrun Nur Abdulmadjid; Nasrullah Idris [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Alion Mangasi Marpaung [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, Rawamangun, Jakarta 12440 (Indonesia); Marincan Pardede [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Jobiliong, Eric [Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Muliadi Ramli [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Heri Suyanto [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Fukumoto, Kenichi; Kagawa, Kiichiro [Research Institute of Nuclear Engineering, University of Fukui, Fukui 910-8507 (Japan)

2013-02-07T23:59:59.000Z

13

Neutron-induced dpa, transmutations, gas production, and helium embrittlement of fusion materials  

E-Print Network (OSTI)

In a fusion reactor materials will be subjected to significant fluxes of high-energy neutrons. As well as causing radiation damage, the neutrons also initiate nuclear reactions leading to changes in the chemical composition of materials (transmutation). Many of these reactions produce gases, particularly helium, which cause additional swelling and embrittlement of materials. This paper investigates, using a combination of neutron-transport and inventory calculations, the variation in displacements per atom (dpa) and helium production levels as a function of position within the high flux regions of a recent conceptual model for the "next-step" fusion device DEMO. Subsequently, the gas production rates are used to provide revised estimates, based on new density-functional-theory results, for the critical component lifetimes associated with the helium-induced grain-boundary embrittlement of materials. The revised estimates give more optimistic projections for the lifetimes of materials in a fusion power plant compared to a previous study, while at the same time indicating that helium embrittlement remains one of the most significant factors controlling the structural integrity of fusion power plant components.

M. R. Gilbert; S. L. Dudarev; D. Nguyen-Manh; S. Zheng; L. W. Packer; J. -Ch. Sublet

2013-11-20T23:59:59.000Z

14

Interpretation of warm prestress-induced fracture toughness based on crack-tip constraint  

SciTech Connect

This study explores the possibility of using J-Q-related crack-tip constraint concepts to provide a basis for both the interpretation of warm prestress (WPS)-induced fracture toughness and their transferability to structural applications. A finite-element boundary-layer formulation based on small-scale yielding (SSY), remote mode I K-dominant assumptions is adopted. Effects of WPS-induced crack-tip constraint are quantified in terms of deviation in either the opening-mode or the mean stress component of the WPS crack-tip fields relative to the reference K-dominant SSY state associated with monotonic-loading conditions. Over the range of WPS load-paths considered the WPS-induced crack-tip constraint closely resembles a spatially varying hydrostatic stress field. Interpretation and transferability of WPS fracture toughness under SSY conditions are specified in terms of the unload and reload ratio.

Shum, D.K.M.

1993-06-01T23:59:59.000Z

15

A Parametric Study of the Lead-Induced Stress Corrosion Cracking of Alloy 690  

Science Conference Proceedings (OSTI)

Alloy 690 steam generator tubing, which has been the material of choice for replacement steam generators, is susceptible to lead-induced stress corrosion cracking (PbSCC) in alkaline environments. No obvious correlation was found between processing parameters or material characteristics and PbSCC susceptibility.

1999-04-22T23:59:59.000Z

16

Modeling Hydrogen-Induced Cracking of Titanium Alloys in Nuclear Waste Repository Environments  

DOE Green Energy (OSTI)

This paper reviews the current understanding of hydrogen-induced cracking (HIC) of Ti Grade 7 and other relevant titanium alloys within the context of the current waste package design for the repository environmental conditions anticipated within the Yucca Mountain repository. The review concentrates on corrosion processes possible in the aqueous environments expected within this site. A brief background discussion of the relevant properties of titanium alloys, the hydrogen absorption process, and the properties of passive film on titanium alloys is presented as the basis for the subsequent discussion of model developments. The key corrosion processes that could occur are addressed individually. Subsequently, the expected corrosion performance of these alloys under the specific environmental conditions anticipated at Yucca Mountain is considered. It can be concluded that, based on the conservative modeling approaches adopted, hydrogen-induced cracking of titanium alloys will not occur under nuclear waste repository conditions since there will not be sufficient hydrogen in the alloy after 10,000 years of emplacement.

F. Hua; K. Mon; P. Pasupathi; G. Gordon

2004-09-08T23:59:59.000Z

17

The effect of crack growth stability induced by residual compressive stresses on strength variability  

Science Conference Proceedings (OSTI)

Rising {ital T}- (or {ital R}-) curve behavior is increasingly being used in order to improve the mechanical reliability of ceramic materials. In this study, the possibility of inducing such behavior using residual compressive stresses is analyzed. The {ital T}-curves obtained for certain residual stress profiles induce crack stability when the stress minima (compressive stress maxima) lie away from the surface of the sample. The consequences of this stabilization on the strength characteristics are a significant reduction in the strength variability and strength insensitivity to the initial flaw size. In addition to these desirable features, considerable strengthening is also obtained. Hence, suitably engineered compressive stress profiles are shown to be a novel and alternative means of enhancing mechanical reliability.

Tandon, R.; Green, D.J. (Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States))

1992-03-01T23:59:59.000Z

18

Crater effects on H and D emission from laser induced low-pressure helium plasma  

Science Conference Proceedings (OSTI)

An experimental study has been performed on the effects of crater depth on the hydrogen and deuterium emission intensities measured from laser plasmas generated in low-pressure helium ambient gas from zircaloy-4 samples doped with different H and D impurity concentrations as well as a standard brass sample for comparison. The results show that aside from emission of the host atom, the emission intensities of other ablated atoms of significantly smaller masses as well as that of the He atom generally exhibit relatively rapid initial decline with increasing crater depth. This trend was found to have its origin in the decreasing laser power density arriving at the crater bottom and thereby weakened the shock wave generated in the crater. As the crater deepened, the declining trend of the intensity appeared to level off as a result of compensation of the decreasing laser power density by the enhanced plasma confinement at increasing crater depth. Meanwhile, the result also reveals the significant contribution of the He-assisted excitation process to the doped hydrogen and deuterium emission intensities, leading to similar crater-depth dependent variation patterns in contrast to that associated with the surface water, with growing dominance of this common feature at the later stage of the plasma expansion. Therefore, a carefully chosen set of gate delay and gate width which are properly adapted to the crater-depth dependent behavior of the emission intensity may produce the desired intrinsic emission data for quantitative depth profiling of H impurity trapped inside the zircaloy wall.

Pardede, Marincan; Lie, Tjung Jie; Kurniawan, Koo Hendrik [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Niki, Hideaki; Fukumoto, Kenichi [Program of Nuclear Power and Energy Safety Engineering, Graduate School of Engineering, Fukui University, Fukui 910-8507 (Japan); Maruyama, Tadashi [Integrated Research Institute, Tokyo Institute of Technology, 4259 Nagatsuda-cho, Midori-ku, Yokohama 226-8503 (Japan); Kagawa, Kiichiro [Department of Physics, Faculty of Education and Regional Studies, Fukui University, 9-1 bunkyo 3-chome, Fukui 910-8507 (Japan); Tjia, May On [Physics of Magnetism and Photonics Research Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia)

2009-09-15T23:59:59.000Z

19

Scaling laws, transient times and shell effects in helium induced nuclear fission  

E-Print Network (OSTI)

Fission excitation functions of He-3 and He-4 induced compound nuclei are shown to scale exactly according to the Bohr-Wheeler transition state prediction once the shell effects are accounted for. The presented method furthermore allows one to model-independently extract values for the shell effects which are in good agreement to those obtained from liquid-drop model calculations. The fact that no deviations from the transition state method have been observed within the experimentally investigated excitation energy regime allows one to assign an upper limit for the transient time of 10 zs.

Th. Rubehn; K. X. Jing; L. G. Moretto; L. Phair; K. Tso; G. J. Wozniak

1996-07-22T23:59:59.000Z

20

Experimental confirmation of photon-induced spin-flip transitions in helium via triplet metastable yield spectra  

SciTech Connect

Doubly excited states below the N=2 ionization threshold are populated by exciting helium atoms in a supersonic beam with monochromatized synchrotron radiation. The fluorescence decay of these states triggers a radiative cascade back to the ground state with large probability to populate long lived singlet and triplet helium metastable states. The yield of metastables is measured using a multichannel plate detector after the beam has passed a singlet-quenching discharge lamp. The variation of the yield observed with the lamp switched on or off is related to the triplet-singlet mixing of the doubly excited states.

Rubensson, Jan-Erik [Department of Physics and Astronomy, Box 530, S-75121 Uppsala (Sweden); Moise, Angelica; Richter, Robert [Sincrotrone Trieste, in Area Science Park, I-34149 Basovizza, Trieste (Italy); Mihelic, Andrej; Bucar, Klemen; Zitnik, Matjaz [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia)

2010-06-15T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Hydrogen induced surface cracking in an 8090 Al-Li alloy during high cycle fatigue  

Science Conference Proceedings (OSTI)

In recent years, there has been an increasing interest in understanding the effects of aggressive or moist environments on the properties of Al-Li alloys. However, most of the existing work has been focused on their stress corrosion cracking resistance. Consequently, only a few reports are available on the environmental fatigue strength of these alloys. Upon exposure to aggressive environments, the fatigue crack propagation resistance can be detrimentally affected. R. Piascik and R. Gangloff found enhanced cyclic crack growth rates in an Al-Li-Cu alloy when a critical water vapor pressure was exceeded. Thermodynamically, at atmospheric pressures, strong interactions between hydrogen and lithium are expected to give rise to stable lithium hydrides. Evidence for the development of hydride phases in Al-Li alloys exposed to hydrogen environments has been reported by various workers. Thus, it is likely that HE via hydride formation can be the relevant mechanisms in Al-Li alloys that have been in contact with hydrogen. Since lithium hydrides are stable up to temperatures of 773 K, previous hydrogen exposure can lead to an irreversible mode of embrittlement. Thus, it was the objective of the present work to investigate the effects of hydrogen during aging on the ensuing high cycle fatigue (HCF) performance of an 8090 Al-Li alloy.

Laffin, C.; Raghunath, C.R.; Lopez, H.F. (Univ. of Wisconsin, Milwaukee, WI (United States). Materials Dept.)

1993-10-01T23:59:59.000Z

22

AN EVALUATION OF HYDROGEN INDUCED CRACKING SUSCEPTIBILITY OF TITANIUM ALLOYS IN US HIGH-LEVEL NUCLEAR WASTE REPOSITORY ENVIRONMENTS  

DOE Green Energy (OSTI)

This paper evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain nuclear waste repository with particular emphasis on the. effect of the oxide passive film on the hydrogen absorption process of titanium alloys being evaluated. The titanium alloys considered in this review include Ti 2, 5 , 7, 9, 11, 12, 16, 17, 18, 24 and 29. In general, the concentration of hydrogen in a titanium alloy can increase due to absorption of atomic hydrogen produced from passive general corrosion of that alloy or galvanic coupling of it to a less noble metal. It is concluded that under the exposure conditions anticipated in the Yucca Mountain repository, the HIC of titanium drip shield will not occur because there will not be sufficient hydrogen in the metal even after 10,000 years of emplacement. Due to the conservatisms adopted in the current evaluation, this assessment is considered very conservative.

G. De; K. Mon; G. Gordon; D. Shoesmith; F. Hua

2006-02-21T23:59:59.000Z

23

Focused helium ion beam milling and deposition  

Science Conference Proceedings (OSTI)

The use of a helium ion microscope with an integrated gas injection system for nanofabrication is explored by demonstrating the milling of fine features into single layered graphene and the controlled deposition of tungsten and platinum wires from gaseous ... Keywords: Beam-induced deposition, Focused ion beam, Gas injection system, Graphene, Helium ion microscope

S. A. Boden; Z. Moktadir; D. M. Bagnall; H. Mizuta; H. N. Rutt

2011-08-01T23:59:59.000Z

24

Radiation-induced instability of MnS precipitates and its possible consequences on irradiation-induced stress corrosion cracking of austenitic stainless steels  

SciTech Connect

Irradiation-assisted stress corrosion cracking (IASCC) is a significant materials issue for the light water reactor (LWR) industry and may also pose a problem for fusion power reactors that will use water as coolant. A new metallurgical process is proposed that involves the radiation-induced release into solution of minor impurity elements not usually thought to participate in IASCC. MnS-type precipitates, which contain most of the sulfur in stainless steels, are thought to be unstable under irradiation. First, Mn transmutes strongly to Fe in thermalized neutron spectra. Second, cascade-induced disordering and the inverse Kirkendall effect operating at the incoherent interfaces of MnS precipitates are thought to act as a pump to export Mn from the precipitate into the alloy matrix. Both of these processes will most likely allow sulfur, which is known to exert a deleterious influence on intergranular cracking, to re-enter the matrix. To test this hypothesis, compositions of MnS-type precipitates contained in several unirradiated and irradiated heats of Type 304, 316, and 348 stainless steels (SSs) were analyzed by Auger electron spectroscopy. Evidence is presented that shows a progressive compositional modification of MnS precipitates as exposure to neutrons increases in boiling water reactors. As the fluence increases, the Mn level in MnS decreases, whereas the Fe level increases. The S level also decreases relative to the combined level of Mn and Fe. MnS precipitates were also found to be a reservoir of other deleterious impurities such as F and O which could be also released due to radiation-induced instability of the precipitates.

Chung, H.M.; Sanecki, J.E. [Argonne National Lab., IL (United States); Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States)

1996-12-01T23:59:59.000Z

25

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

Science Conference Proceedings (OSTI)

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.

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

1996-02-01T23:59:59.000Z

26

Cracking knuckles  

NLE Websites -- All DOE Office Websites (Extended Search)

Cracking knuckles Cracking knuckles Name: Renee Knuckles Location: N/A Country: N/A Date: N/A Question: Does cracking your joints especially the knuckles cause arthritis? What are some of the results of doing so? Replies: Cracking knuckles has NEVER been associated with causing arthritis. This concept is as wrong as saying weight lifting makes you short, or playing basketball makes you tall. The "popping" of the knuckles results from forcing joint fluid to very rapidly pass from one side of the joint to the other, where the "sides" are partitioned off by the main bones of the joint. Let me rephrase that: a joint is an area where two or more separate and distinct bones meet. The joint fluid provides a cushioning between the joints so that they don't grate into each other. Cracking your knuckles forces the joint fluid from one part of the joint to another, and the popping sound is just the result of the high pressured rushing of fluid.

27

Hydrogen Assisted Cracking  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking (EAC): Laboratory Research and Field Experiences: Hydrogen Assisted Cracking Program Organizers: Suresh Divi, TIMET

28

Status Review of Initiation of Environmentally Assisted Cracking and Short Crack Growth  

Science Conference Proceedings (OSTI)

This report reviews current knowledge of environmentally assisted cracking EAC initiation and short crack growth by stress corrosion cracking, strain-induced corrosion cracking, and, to a lesser extent, corrosion fatigue in nickel base alloys, austenitic stainless steels, and carbon and low-alloy steels exposed to typical pressurized water reactor PWR and boiling water reactor BWR aqueous environments. The document identifies key gaps in knowledge and recommends areas where additional experimental work i...

2005-12-06T23:59:59.000Z

29

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

Science Conference Proceedings (OSTI)

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.

Julian K. Benz; Richard N. Wright

2013-10-01T23:59:59.000Z

30

SCREENING TESTS FOR IMPROVED METHANE CRACKING MATERIALS  

DOE Green Energy (OSTI)

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.

Klein, J; Jeffrey Holder, J

2007-07-16T23:59:59.000Z

31

Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments  

SciTech Connect

The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the helium coolant. • Evaluate grain boundary engineering as a method to mitigate stress-assisted grain boundary oxidation and creep crack growth of candidate alloys in impure helium. The maximum primary helium coolant temperature in the high-temperature reactor is expected to be 850-1,000°C.Corrosion may involve oxidation, carburization, or decarburization mechanisms depending on the temperature, oxygen partial pressure, carbon activity, and alloy composition. These corrosion reactions can substantially affect long-term mechanical properties such as crack- growth rate and fracture toughness, creep rupture, and fatigue. Although there are some studies on the effects of impurities in helium coolant on creep rupture and fatigue strength, very little is known about their effects on creep crack initiation and crack growth rate at elevated temperatures.

Crone, Wendy; Cao, Guoping; Sridhara, Kumar

2013-05-31T23:59:59.000Z

32

Creep Crack Growth  

Science Conference Proceedings (OSTI)

Table 3   Creep crack growth constants b and m for various ferritic steels...and Banerji, â??Creep Crack Growth Behavior

33

Environmentally Assisted Cracking: Nuclear  

Science Conference Proceedings (OSTI)

About this Symposium. Meeting, Materials Science & Technology 2014. Symposium, Environmentally Assisted Cracking: Nuclear. Sponsorship. Organizer(s) ...

34

Shock Experiments on Pre-Compressed Fluid Helium  

Science Conference Proceedings (OSTI)

We summarize current methods and results for coupling laser-induced shocks into pre-compressed Helium contained in a diamond anvil cell (DAC). We are able to load helium, hydrogen, deuterium, and helium-hydrogen mixtures into a DAC and propagate a laser-generated shock into the pre-compressed sample. This technique has allowed us to measure the Hugoniot for helium at initial densities ranging from 1 to 3.5 times liquid density. We have developed and used a methodology whereby all of our measurements are referenced to crystalline quartz, which allows us to update our results as the properties of quartz are refined in the future. We also report the identification and elimination of severe electro-magnetic pulses (EMP) associated with plasma stagnation associated with ablation in a DAC.

Eggert, J. H.; Celliers, P. M.; Hicks, D. G.; Rygg, J. R.; Collins, G. W. [Lawrence Livermore National Laboratory, Livermore CA (United States); Brygoo, S.; Loubeyre, P. [Commissariat a l'Energie Atomique, Bruyeres-le-Chatel (France); McWilliams, R. S.; Spaulding, D.; Jeanloz, R. [University of California, Berkeley, CA (United States); Boehly, T. R. [University of Rochester, Rochester, NY (United States)

2009-09-10T23:59:59.000Z

35

Helium dilution refrigeration system  

DOE Patents (OSTI)

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

Roach, P.R.; Gray, K.E.

1988-09-13T23:59:59.000Z

36

Cracks Cleave Crystals  

E-Print Network (OSTI)

The problem of finding what direction cracks should move is not completely solved. A commonly accepted way to predict crack directions is by computing the density of elastic potential energy stored well away from the crack tip, and finding a direction of crack motion to maximize the consumption of this energy. I provide here a specific case where this rule fails. The example is of a crack in a crystal. It fractures along a crystal plane, rather than in the direction normally predicted to release the most energy. Thus, a correct equation of motion for brittle cracks must take into account both energy flows that are described in conventional continuum theories and details of the environment near the tip that are not.

Michael Marder

2004-03-05T23:59:59.000Z

37

Thermal integration of processes to recover helium  

SciTech Connect

New applications for helium have resulted in significant growth in helium demand in recent years. The primary source of helium in the USA is natural gas reservoirs. Typically natural gas reservoirs that contain helium also contain nitrogen. The presence of nitrogen requires that the heating value of the gas be upgraded using nitrogen rejection units (NRU). Thermal integration of the NRU process with the helium recovery process is described. Further integration of NRU and helium recovery process to produce cold helium gas suitable for use as a feed to a helium liquefier is also described. A key aspect of the integrated process is the use of refrigeration from the NRU to reduce power requirements, and capital cost for the helium recovery process.

Pahade, R.F.; Maloney, J.J.; Fisher, T.F. (Union Carbide Corp., Linde Div., Tonawanda, NY (US))

1988-01-01T23:59:59.000Z

38

The influence of crack-imbalance orientation and orbital evolution for an extended cracked Jeffcott rotor  

E-Print Network (OSTI)

Vibration peaks occurring at rational fractions of the fundamental rotating critical speed, here named Local Resonances, facilitate cracked shaft detection during machine shut-down. A modified Jeffcott-rotor on journal bearings accounting for gravity effects and oscillating around nontrivial equilibrium points is employed. Modal parameter selection allows this linear model to represent first mode characteristics of real machines. Orbit evolution and vibration patterns are analyzed, yielding useful results. Crack detection results indicate that, instead of 1x and 2x components, analysis of the remaining local resonances should have priority; this is due to crack-residual imbalance interaction and to 2x multiple induced origins. Therefore, local resonances and orbital evolution around 1/2, 1/3 and 1/4 of the critical speed are emphasized for various crack-imbalance orientations.

Julio Gomez-Mancilla; Jean-Jacques Sinou; V. R. Nosov; Fabrice Thouverez; A. Zambrano

2008-01-19T23:59:59.000Z

39

LPG storage vessel cracking experience  

SciTech Connect

In order to evaluate liquefied petroleum gas (LPG) handling and storage hazards, Caltex Petroleum Corp. (Dallas) surveyed several installations for storage vessel cracking problems. Cracking was found in approximately one-third of the storage vessels. In most cases, the cracking appeared to be due to original fabrication problems and could be removed without compromising the pressure containment. Several in-service cracking problems found were due to exposure to wet hydrogen sulfide. Various procedures were tried in order to minimize the in-service cracking potential. One sphere was condemned because of extensive subsurface cracking. This article's recommendations concern minimizing cracking on new and existing LPG storage vessels.

Cantwell, J.E. (Caltex Petroleum Corp., P.O. Box 619500, Dallas, TX (US))

1988-10-01T23:59:59.000Z

40

LPG storage vessel cracking experience  

SciTech Connect

As part of an overall company program to evaluate LPG handling and storage hazards the authors surveyed several installations for storage vessel cracking problems. Cracking was found in approximately one third of the storage vessels. In most cases the cracking appeared due to original fabrication problems and could be removed without compromising the pressure containment. Several in-service cracking problems due to exposure to wet hydrogen sulfide were found. Various procedures were tried in order to minimize the in-service cracking potential. One sphere was condemned because of extensive subsurface cracking. Recommendations are made to minimize cracking on new and existing LPG storage vessels.

Cantwell, J.E.

1988-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Pulsed helium ionization detection system  

DOE Patents (OSTI)

A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

Ramsey, R.S.; Todd, R.A.

1985-04-09T23:59:59.000Z

42

Corrosion Fatigue Crack Growth and Stress-Corrosion Cracking in ...  

Science Conference Proceedings (OSTI)

Abstract Scope, The high stress ratio (R=0.85) corrosion fatigue crack growth kinetics and stress-corrosion cracking resistance of sensitized (70-175 °C up to ...

43

Precision spectroscopy of the helium atom.  

SciTech Connect

Persistent efforts in both theory and experiment have yielded increasingly precise understanding of the helium atom. Because of its simplicity, the helium atom has long been a testing ground for relativistic and quantum electrodynamic effects in few-body atomic systems theoretically and experimentally. Comparison between theory and experiment of the helium spectroscopy in 1s2p{sup 3}P{sub J} can potentially extract a very precise value of the fine structure constant a. The helium atom can also be used to explore exotic nuclear structures. In this paper, we provide a brief review of the recent advances in precision calculations and measurements of the helium atom.

Hu, S.-M.; Lu, Z.-T.; Yan, Z.-C.; Physics; Univ. of Science and Technology of China; Univ. of Chicago; Univ. of New Brunswick

2009-06-01T23:59:59.000Z

44

High-temperature helium-loop facility  

Science Conference Proceedings (OSTI)

The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100/sup 0/F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system.

Tokarz, R.D.

1981-09-01T23:59:59.000Z

45

Nanostructuring of molybdenum and tungsten surfaces by low-energy helium ions  

Science Conference Proceedings (OSTI)

The formation of metallic nanostructures by exposure of molybdenum and tungsten surfaces to high fluxes of low energy helium ions is studied as a function of the ion energy, plasma exposure time, and surface temperature. Helium plasma exposure leads to the formation of nanoscopic filaments on the surface of both metals. The size of the helium-induced nanostructure increases with increasing surface temperature while the thickness of the modified layer increases with time. In addition, the growth rate of the nanostructured layer also depends on the surface temperature. The size of the nanostructure appears linked with the size of the near-surface voids induced by the low energy ions. The results presented here thus demonstrate that surface processing by low-energy helium ions provides an efficient route for the formation of porous metallic nanostructures.

De Temmerman, Gregory; Bystrov, Kirill; Zielinski, Jakub J.; Balden, Martin; Matern, Gabriele; Arnas, Cecile; Marot, Laurent [FOM Institute DIFFER, Ducth Institute For Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Max Planck Institute for Plasma Physics, EURATOM Association, 85748 Garching (Germany); Laboratoire PIIM, CNRS/Aix-Marseille Universit, 13397 Marseille (France); Department of Physics, University of Basel, Basel, CH-4056 (Switzerland)

2012-07-15T23:59:59.000Z

46

Metastable Helium Molecules as Tracers in Superfluid {sup 4}He  

SciTech Connect

Metastable helium molecules generated in a discharge near a sharp tungsten tip immersed in superfluid {sup 4}He are imaged using a laser-induced-fluorescence technique. By pulsing the tip, a small cloud of He{sub 2}* molecules is produced. We can determine the normal-fluid velocity in a heat-induced counterflow by tracing the position of a single molecule cloud. As we run the tip in continuous field-emission mode, a normal-fluid jet from the tip is generated and molecules are entrained in the jet. A focused 910 nm pump laser pulse is used to drive a small group of molecules to the first excited vibrational level of the triplet ground state. Subsequent imaging of the tagged molecules with an expanded 925 nm probe laser pulse allows us to measure the flow velocity of the jet. The techniques we developed provide new tools in quantitatively studying the normal fluid flow in superfluid helium.

Guo, W.; Wright, J. D.; Cahn, S. B.; Nikkel, J. A.; McKinsey, D. N. [Physics Department, Yale University, New Haven, Connecticut 06515 (United States)

2009-06-12T23:59:59.000Z

47

Catalytic cracking process  

Science Conference Proceedings (OSTI)

Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

Lokhandwala, Kaaeid A. (Union City, CA); Baker, Richard W. (Palo Alto, CA)

2001-01-01T23:59:59.000Z

48

Analysis of Cracked Pipe Weldments  

Science Conference Proceedings (OSTI)

EPRI estimation formulas for predicting loads necessary for crack initiation and instability can facilitate leak-before-break analysis of cracked nuclear piping. Finite-element calculations carried out in this study verified the accuracy of these formulas for analyzing through-the-wall cracks in bimetallic weldments.

1987-02-01T23:59:59.000Z

49

In Beam Tests of Implanted Helium Targets  

E-Print Network (OSTI)

Targets consisting of 3,4He implanted into thin aluminum foils (approximately 100, 200 or 600 ug/cm^2) were prepared using intense (a few uA) helium beams at low energy (approximately 20, 40 or 100 keV). Uniformity of the implantation was achieved by a beam raster across a 12 mm diameter tantalum collimator at the rates of 0.1 Hz in the vertical direction and 1 Hz in the horizontal direction. Helium implantation into the very thin (approximately 80-100 ug/cm^2) aluminum foils failed to produce useful targets (with only approximately 10% of the helium retained) due to an under estimation of the range by the code SRIM. The range of low energy helium in aluminum predicted by Northcliffe and Shilling and the NIST online tabulation are observed on the other hand to over estimate the range of low energy helium ions in aluminum. An attempt to increase the amount of helium by implanting a second deeper layer was also carried out, but it did not significantly increase the helium content beyond the blistering limit (approximately 6 x 10^17 helium/cm^2). The implanted targets were bombarded with moderately intense 4He and 16O beams of 50-100 particle nA . Rutherford Back Scattering of 1.0 and 2.5 MeV proton beams and recoil helium from 15.0 MeV oxygen beams were used to study the helium content and profile before, during and after bombardments. We observed the helium content and profile to be very stable even after a prolonged bombardment (up to two days) with moderately intense beams of 16O or 4He. Helium implanted into thin (aluminum) foils is a good choice for thin helium targets needed, for example, for a measurement of the 3he(a,g)7Be reaction and the associated S34 astrophysical cross section factor (S-factor).

J. E. McDonald; R. H. France III; R. A. Jarvis; M. W. Ahmed; M. A. Blackston; Th. Delbar; M. Gai; T. J. Kading; Y. Parpottas; B. A. Perdue; R. M. Prior; D. A. Rubin; M. C. Spraker; J. D. Yeomans; L. Weissman; H. R. Weller; E. L. Wilds Jr; ;; UHartford; GCSU; LNS/UConn; TUNL/Duke; UCL/LLN; Yale; NGCSU

2006-08-16T23:59:59.000Z

50

Iodine Stabilized Helium-Neon Laser  

Science Conference Proceedings (OSTI)

... stabilized lasers or spectral lamps that have been recommended for use by international consensus. The iodine stabilized helium-neon laser is just ...

51

Helium turbines for high-temperature reactors  

SciTech Connect

From joint meeting of the VDE and VDI; Dusseldorf, Ger. (17 Oct 1972). The designs of turbines with air and helium as working media are compared, and volume flow, mass flow, sound velocity, stage number, and other characteristics are individually dealt with. Similar comparisons are made regarding connecting lines and heat exchangers. The combination of the helium turbine with hightemperature reactors is described. Problems of the integrated and non- integrated method of single cycle plants and helium turbines, the use of dry cooling towers and the development of helium turbines are discussed. (GE)

Knuefer, H.

1973-12-01T23:59:59.000Z

52

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

SciTech Connect

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.

Bruemmer, Stephen M.; Thomas, Larry E.

2010-04-05T23:59:59.000Z

53

Fermilab Central Helium Liquefier Operations  

SciTech Connect

The Central Helium Liquefier (CHL), in conjunction with 24 satellite refrigerators, supplies refrigeration for the Fermilab superconducting accelerator. Liquid from the CHL is transported in a six kilometer circular transfer line and each satellite withdraws the amount required to boost its refrigeration capacity to the necessary level. Unused liquid is presently returned to compressor suction through a 250 kW calorimeter-heater. A helium gas flow of 1.1 kg/s is supplied to the cold box at 15 bars pressure. The gas flows through a demister and an oil adsorgber before it enters the cold box. In the cold box, manufactured by Koch Process Systems and Sulzer Brothers, Ltd., the gas is first cooled by liquid nitrogen and then the flow is split. Three quarters of the flow is further cooled by a series/parallel combination of three oil bearing turbines and then returned to the low pressure side of the heat exchangers. The return gas is used to cool the remaining high pressure gas which is then expanded to 3.5 bars in a 900 L receiver. From there the fluid is transferred into a distribution box, and then routed to either a collection dewar, directly to the ring, or to a heater. The liquid helium, which is utilized by the satellites to increase their cooling capacity, is warmed to near ambient temperature in the satellite heat exchangers. The satellite compressors return the excess inventory to the CHL via a 20 bar gas header. This gas is injected into the high pressure supply to the cold box. The system is shown.

Hodge, G.A.; Rihel, R.K.; Stone, M.E.; Walker, R.J.; /Fermilab

1983-01-01T23:59:59.000Z

54

Modernizing helium liquefier G-3  

SciTech Connect

The authors describe the process for modernizing the existing liquefier with minimum alteration of its cooling block, that liquefier being helium expansion-type liquefier G-3, made at the Institute of Physical Problems, Academy of Sciences of the USSR, which operates at a stable output of 40 liters/h. A nitrogen tank and a pistontype expander in the preliminary cooling stages and a throttle in the liquefaction stages are used in G-3. Improving the efficiency of such a cooling cycle is limited by the fact that the optimal parameters of throttle stage of liquefaction do not match with the optimal parameters of the expander in the preliminary cooling stages. Thus, for improving cycle efficiency the pressure in the preliminary stages must be increased but reduced in the liquefaction stage. This paper also presents the solution to this problem. It is further demonstrated that the use of vapor-liquid expander in the liquefaction stage of helium cooling cycle helps increase the output of the unit by 40% in a relatively simple way.

Golikov, G.E.; Danilov, I.B.

1985-02-01T23:59:59.000Z

55

Environmentally Assisted Cracking of Ni-Base Alloys [Corrosion and  

NLE Websites -- All DOE Office Websites (Extended Search)

LWRs > Environmentally Assisted LWRs > Environmentally Assisted Cracking of Ni-Base Alloys Capabilities Materials Testing Environmentally Assisted Cracking (EAC) of Reactor Materials Corrosion Performance/Metal Dusting Overview Light Water Reactors Fatigue Testing of Carbon Steels and Low-Alloy Steels Environmentally Assisted Cracking of Ni-Base Alloys Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless Steels Steam Generator Tube Integrity Program Air Oxidation Kinetics for Zr-based Alloys Fossil Energy Fusion Energy Metal Dusting Publications List Irradiated Materials Steam Generator Tube Integrity Other Facilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Corrosion and Mechanics of Materials Light Water Reactors

56

Analysis of Crack Growth Data  

Science Conference Proceedings (OSTI)

Table 3   Methods for calculating crack growth rates...the derivative at the midpoint of a data set. These methods use

57

Environmentally Assisted Cracking of Materials  

Science Conference Proceedings (OSTI)

Development of Alternating Current Potential Drop (ACPD) method for the detection of Primary Water Stress Corrosion Cracking initiation in Stainless Steels and ...

58

Environmentally Assisted Cracking of Materials  

Science Conference Proceedings (OSTI)

In-Situ Repairs of Oil Industry Pipelines, Tanks and Vessels by Welding Using Metal Arc Welding Under Oil (MAW-UO) · Interpretation of Crack Initiation and ...

59

PICEP: Pipe Crack Evaluation Program  

Science Conference Proceedings (OSTI)

We describe a computer program that calculates the crack-opening area, the critical (stable) crack length and the two-phase flow rate through cracks in ductile stainless steel pipes and steam generator tubes. The program is useful in performing leak-before-break calculations in order to demonstrate detectable leak rates prior to a through-wall flaw reaching critical size. Necessary input to the code includes a definition of material properties, loads, thermal-hydraulic conditions, pipe geometry, and crack orientation. User information is provided in the report.

Norris, D.; Okamoto, A.; Chexal, B.; Griesbach, T.

1984-08-01T23:59:59.000Z

60

Shale oil cracking. 1. Kinetics  

DOE Green Energy (OSTI)

Experiments were conducted to determine kinetics for thermal cracking of shale oil vapor over shale. Cracking temperatures of 504 to 610/sup 0/C and residence times of 2 to 11 seconds were used. A first-order Arrhenius rate expression and stoichiometry were obtained. Also observed were changes in the oil quality. Cracking decreased the H/C ratio, increased the nitrogen content, and decreased the pour point of the oil. Gas-phase oil cracking is contrasted to liquid-phase oil coking as a loss mechanism in oil-shale retorting.

Burnham, A.K.; Taylor, J.R.

1979-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

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

Science Conference Proceedings (OSTI)

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.

Hashida, Toshiyuki; Sato, Kazushi; Takahashi, Hideaki

1993-01-28T23:59:59.000Z

62

A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal...  

Open Energy Info (EERE)

Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal System Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Helium Isotope...

63

SAES ST 909 PILOT SCALE METHANE CRACKING TESTS  

DOE Green Energy (OSTI)

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.

Klein, J; Henry Sessions, H

2007-07-02T23:59:59.000Z

64

Theory and modelling of helium enrichment in plasma experiments with pump limiters  

DOE Green Energy (OSTI)

Helium enrichment in the exhaust gas stream flowing from a hydrogen-helium plasma is studied using an analytical theory and Monte Carlo simulations. To provide a sensitive experimental test in a tokamak, an unusual configuration, inverted from traditional designs, is proposed for a pump limiter. The principle can be tested in other plasma devices as well. The theory suggests that for typical plasma edge conditions in a confinement device, namely, n = 10/sup 13/cm/sup -3/ and T/sub i/ = T/sub e/ approx. = 5-30eV, helium enrichment in the neutral gas exhaust stream can be very high, in the range 5 to 7, relative to the helium-hydrogen ratio in the plasma. Such high enrichment factors are achieved by exploiting the difference between the ionization rates of hydrogen and helium and the negligible helium charge exchange rate at these plasma conditions. A limiter arrangement is proposed in which the natural curvature of the toroidal magnetic field is used to isolate, using the plasma itself, the point of plasma neutralization from the location of the gas exhaust. The plasma region then acts to preferentially screen the recycling hydrogen by the processes of ionization and of charge-exchange-induced losses at open boundaries. The theory and analysis suggests that an experiment can provide a sensitive test of modules used to describe the plasma edge and of atomic and surface physics data used in these models.

Prinja, A.K.; Conn, R.W.

1984-01-01T23:59:59.000Z

65

Effect of Thermomechanical Processing on Fatigue Crack ...  

Science Conference Proceedings (OSTI)

gechanical driving force such as crack opening distance (COD) . However, at hold time loading, the crack growth rate is drastically decreased with an increase of ...

66

Intergranular Stress Corrosion Cracking (IGSCC) Mechanism of ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2012. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title ...

67

Weldability Tests for Evaluating Cracking Susceptibility  

Science Conference Proceedings (OSTI)

Table 2   Weldability tests used to evaluate susceptibility to cracking...used to evaluate susceptibility to cracking Test Fields of use Controllable variables Type of data Specialized equipment Relative cost Lehigh restraint test Weld metal hot and cold cracking, root cracking,

68

Stable crack growth estimates based on effective crack length and crack-opening displacements  

SciTech Connect

A method was developed for estimating the amount of stable crack growth that has occurred in a fracture toughness specimen that were loaded into the plastic range and for which only a monotonically increasing load-displacement curve was measured. The method was applied to data from several pressure vessel steels. The resulting J vs ..delta..a values compare favorably with a resistance curve obtained by the multiple specimen heat-tinting technique for A533, Grade B, Class 1 steel. The method for estimating stable crack growth uses several existing concepts heretofore mainly used separately. These concepts include an approximate expression for J for the compact specimen proposed by Andrews, the effective crack length concept of McCabe and Landes, the UK representation of the crack profile as a pair of straight lines intersecting at a hinge point, and Well's expression, J = m sigma/sub y/delta, for relating the crack-opening displacement to the value of J. The value of the constraint factor, m, at the advancing crack tip is estimated by means of a relation between ductility and fracture toughness. When calculated with respect to the COD at the original fatigue crack tip, the constraint factor, m/sub o/, is found to have a value consistently close to 2.0 for compact and precracked Charpy specimens. The method of estimation requires no auxiliary load-deflection measurements or calculations, and so permits single specimen estimates of stable crack growth to be made without the necessity of making high precision unloading compliance measurements.

Merkle, J.G.; Hudson, C.E.

1979-01-01T23:59:59.000Z

69

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

Science Conference Proceedings (OSTI)

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.

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

2003-10-31T23:59:59.000Z

70

Aspects of Stress Corrosion Cracking Relevant to Irradiation-Assisted Stress Corrosion Cracking (IASCC)  

Science Conference Proceedings (OSTI)

This report provides a comprehensive survey of crack initiation issues in irradiation-assisted stress corrosion cracking (IASCC). It considers microcracking on smooth specimens and the transition from microcracking to stable crack propagation.

2002-05-02T23:59:59.000Z

71

Dynamic Simulation of a Helium Liquefier  

SciTech Connect

Dynamic behavior of a helium liquefier has been studied in detail with a Cryogenic Process REal-time SimulaTor (C-PREST) at the National Institute for Fusion Science (NIFS). The C-PREST is being developed to integrate large-scale helium cryogenic plant design, operation and maintenance for optimum process establishment. As a first step of simulations of cooldown to 4.5 K with the helium liquefier model is conducted, which provides a plant-process validation platform. The helium liquefier consists of seven heat exchangers, a liquid-nitrogen (LN2) precooler, two expansion turbines and a liquid-helium (LHe) reservoir. Process simulations are fulfilled with sequence programs, which were implemented with C-PREST based on an existing liquefier operation. The interactions of a JT valve, a JT-bypass valve and a reservoir-return valve have been dynamically simulated. The paper discusses various aspects of refrigeration process simulation, including its difficulties such as a balance between complexity of the adopted models and CPU time.

Maekawa, R.; Ooba, K.; Mito, T. [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan); Nobutoki, M. [Nippon Sanso Co., Kawasaki, Kanagawa, 210-0861 (Japan)

2004-06-23T23:59:59.000Z

72

Helium release from radioisotope heat sources  

DOE Green Energy (OSTI)

Diffusion of helium in /sup 238/PuO/sub 2/ fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel.

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01T23:59:59.000Z

73

Use Computational Model to Design and Optimize Welding Conditions to Suppress Helium Cracking during Welding  

Energy.gov (U.S. Department of Energy (DOE))

Today, welding is widely used for repair, maintenance and upgrade of nuclear reactor components. As a critical technology to extend the service life of nuclear power plants beyond 60 years, weld...

74

Predicting the Behavior of Small Fatigue Cracks - Programmaster.org  

Science Conference Proceedings (OSTI)

are effective at providing crack propagation resistance in many materials and composites, these mechanisms result in a crack size dependence (i.e., “small crack ...

75

Helium-filled aluminum flight tubes  

NLE Websites -- All DOE Office Websites (Extended Search)

Helium-filled aluminum flight tubes. Helium-filled aluminum flight tubes. Detector housing for the CCD camera lens, mirror, and scintillator. For more information, contact Instrument Scientist: Hassina Bilheux, bilheuxhn@ornl.gov, 865.384.9630 neutrons.ornl.gov/instruments/HFIR/factsheets/Instrument-cg1d.pdf The CG-1D beam is used for neutron imaging measurements using a white beam. Apertures (with different diameters D (pinhole geometry) are used at the entrance of the helium-filled flight path to allow L/D variation from 400 to 800. L is the distance between the aperture and the detector (where the image is produced). Samples sit on a translation/ rotation stage for alignment and tomography purposes. Detectors for CG-1D include

76

SCREW COMPRESSOR CHARACTERISTICS FOR HELIUM REFRIGERATION SYSTEMS  

SciTech Connect

The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression.At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss

Ganni, Venkatarao; Knudsen, Peter; Creel, Jonathan; Arenius, Dana; Casagrande, Fabio; Howell, Matt

2008-03-01T23:59:59.000Z

77

Properties of hydrogen/helium accretion plasmas  

DOE Green Energy (OSTI)

We study the properties of impulsively-heated plasmas initially composed of hydrogen and helium. We follow the time-dependent behavior of the ion and electron temperatures, the pair density, and the densities of hydrogen, helium, and nuclei formed in fusion and breakup reactions. We also consider neutron production and escape, and calculate the 0.431 and 0.478 MeV line luminosities from ..cap alpha..-..cap alpha.. fusion reactions, and the 2.22 MeV line luminosity from neutron capture on protons. 13 refs., 3 figs., 1 tab.

Guessoum, N.; Dermer, C.D.

1988-02-01T23:59:59.000Z

78

STUDY OF HELIUM RETENTION IN NANO-CAVITY ...  

Science Conference Proceedings (OSTI)

STUDY OF HELIUM RETENTION IN NANO-CAVITY TUNGSTEN AS A FIRST WALL IN A FUSION CHAMBER USING NEUTRON DEPTH ...

79

Search for the eta-mesic helium at COSY  

E-Print Network (OSTI)

We review status and perspectives of the search of the eta-mesic helium at the cooler synchrotron COSY.

P. Moskal

2009-09-22T23:59:59.000Z

80

Origin of undesirable cracks during layer transfer  

E-Print Network (OSTI)

We investigate the origin of undesirable transverse cracks often observed in thin films obtained by the layer transfer technique. During this process, two crystals bonded to each other containing a weak plan produced by ion implantation are heated to let a thin layer of one of the material on the other. The level of stress imposed on the film during the heating phase due to the mismatch of thermal expansion coefficients of the substrate and the film is shown to be the relevant parameter of the problem. In particular, it is shown that if the film is submitted to a tensile stress, the microcracks produced by ion implantation are not stable and deviate from their straight trajectory making the layer transfer process impossible. However, if the compressive stress exceeds a threshold value, after layer transfer, the film can buckle and delaminate, leading to transverse cracks induced by bending. As a result, we show that the imposed stress \\sigma_m - or equivalently the heating temperature - must be within the ran...

Ponson, Laurent; Atwater, Harry; Ravichandran, Guruswami; Bhattacharya, Kaushik

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Nonlinear structural crack growth monitoring  

DOE Patents (OSTI)

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.

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

2002-01-01T23:59:59.000Z

82

The effect of aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels  

Science Conference Proceedings (OSTI)

The effect of elevated temperature aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels is discussed in terms of the several parameters which influence such behavior. These parameters include water chemistry, impurities within the steels themselves, as well as factors such as the water flow rate, loading waveform and loading rates. Some of these parameters have similar effects upon both crack initiation and propagation, while others exhibit different effects in the two stages of cracking. In the case of environmentally-assisted crack (EAC) growth, the most important impurities within the steel are metallurgical sulfide inclusions which dissolve upon contact with the water. A ``critical`` concentration of sulfide ions at the crack tip can then induce environmentally-assisted cracking which proceeds at significantly increased crack growth rates over those observed in air. The occurrence, or non-occurrence, of EAC is governed by the mass-transport of sulfide ions to and from the crack-tip region, and the mass-transport is discussed in terms of diffusion, ion migration, and convection induced within the crack enclave. Examples are given of convective mass-transport within the crack enclave resulting from external free stream flow. The initiation of fatigue cracks in elevated temperature aqueous environments, as measured by the S-N fatigue lifetimes, is also strongly influenced by the parameters identified above. The influence of sulfide inclusions does not appear to be as strong on the crack initiation process as it is on crack propagation. The oxygen content of the environment appears to be the dominant factor, although loading frequency (strain rate) and temperature are also important factors.

James, L.A. [Westinghouse Electric Corp., West Mifflin, PA (United States). Bettis Atomic Power Lab.; Van Der Sluys, W.A. [Babcock and Wilcox Co., Alliance, OH (United States)

1996-01-01T23:59:59.000Z

83

Intergranular Cracking of Brass Sprinkler Heads  

Science Conference Proceedings (OSTI)

Symposium, Charles R. Morin Memorial Symposium on Failure Analysis and Prevention. Presentation Title, Intergranular Cracking of Brass Sprinkler Heads.

84

Stress Corrosion Cracking of Brass: A Comparative Study on ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well · Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...

85

On the Fatigue Crack Propagation Behavior of Superalloys at ...  

Science Conference Proceedings (OSTI)

ON THE FATIGUE CRACK PROPAGATION BEHAVIOR. OF SUPERALLOYS AT ... the FCP resistance of superalloys ... lead to poor crack propagation behavior.

86

Environmental Effects on Fatigue Crack Growth Rates in Sour ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well · Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...

87

Environmental Cracking Resistance of High Nickel Alloys (CRAs  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well · Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...

88

Corrosion and Cracking of Carbon Steel in Fuel Grade Ethanol  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well · Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...

89

Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well · Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...

90

L3 Milestone Use Computational Model to Design and Optimize Welding Conditions to Suppress Helium  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

L3 Milestone L3 Milestone Use Computational Model to Design and Optimize Welding Conditions to Suppress Helium Cracking during Welding June 2012 Wei Zhang and Zhili Feng, ORNL Eric Willis, EPRI Background and Objectives Today, welding is widely used for repair, maintenance and upgrade of nuclear reactor components. As a critical technology to extend the service life of nuclear power plants beyond 60 years, weld technology must be further developed to meet new challenges associated with the aging of the plants, such as control and mitigation of the detrimental effects of weld residual stresses and repair of highly irradiated materials. To meet this goal, fundamental understanding of the "welding" effect is necessary for development of new and improved welding technologies.

91

Time dependence of liquid-helium fluorescence  

SciTech Connect

The time dependence of extreme ultraviolet (EUV) fluorescence following an ionizing radiation event in liquid helium is observed and studied in the temperature range from 250 mK to 1.8 K. The fluorescence exhibits significant structure including a short ({approx}10 ns) strong initial pulse followed by single photons whose emission rate decays exponentially with a 1.6-{mu}s time constant. At an even longer time scale, the emission rate varies as '1/time' (inversely proportional to the time after the initial pulse). The intensity of the '1/time' component from {beta} particles is significantly weaker than those from {alpha} particles or neutron capture on {sup 3}He. It is also found that for {alpha} particles, the intensity of this component depends on the temperature of the superfluid helium. Proposed models describing the observed fluorescence are discussed.

McKinsey, D.N.; Brome, C.R.; Dzhosyuk, S.N.; Mattoni, C.E.H.; Yang, L.; Doyle, J.M. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Golub, R.; Habicht, K.; Korobkina, E. [Hahn-Meitner Institut, Berlin-Wannsee (Germany); Huffman, P.R.; Thompson, A.K. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Lamoreaux, S.K. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2003-06-01T23:59:59.000Z

92

Combined cold compressor/ejector helium refrigerator  

DOE Patents (OSTI)

A refrigeration apparatus having an ejector operatively connected with a cold compressor to form a two-stage pumping system. This pumping system is used to lower the pressure, and thereby the temperature of a bath of boiling refrigerant (helium). The apparatus as thus arranged and operated has substantially improved operating efficiency when compared to other processes or arrangements for achieving a similar low pressure.

Brown, Donald P. (Southold, NY)

1985-01-01T23:59:59.000Z

93

Studies of Helium Distribution in Metal Tritides  

SciTech Connect

The distribution of helium (3HE) in LiT, TiT2, and UT3, which are regarded as representative metal tritides, was investigated using pulse nuclear magnetic resonance (NMR) techniques. Analyses of the NMR lineshapes and nuclear relaxation times indicate the 3He atoms are trapped in microscopic gas bubbles for each tritide. The effects of concentration and temperature on the 3He distributions were investigated as well.

Bowman, Jr., R. C.; Attalla, A.

1976-03-01T23:59:59.000Z

94

Combined cold compressor/ejector helium refrigerator  

DOE Patents (OSTI)

A refrigeration apparatus having an ejector operatively connected with a cold compressor to form a two-stage pumping system. This pumping system is used to lower the pressure, and thereby the temperature of a bath of boiling refrigerant (helium). The apparatus as thus arranged and operated has substantially improved operating efficiency when compared to other processes or arrangements for achieving a similar low pressure.

Brown, D.P.

1984-06-05T23:59:59.000Z

95

Hydrogen Production Using the Modular Helium Reactor  

DOE Green Energy (OSTI)

The high-temperature characteristics of the Modular Helium Reactor (MHR) make it a strong candidate for the production of hydrogen using either thermochemical or high-temperature electrolysis (HTE) processes. Using heat from the MHR to drive a Sulfur-Iodine (S-I) thermochemical hydrogen process has been the subject of a DOE sponsored Nuclear Engineering Research Initiative (NERI) project lead by General Atomics, with participation from the Idaho National Engineering and Environmental Laboratory (INEEL) and Texas A&M University. While the focus of much of the initial work was on the S-I thermochemical production of hydrogen, recent activities have also included development of a preconceptual design for an integral HTE hydrogen production plant driven by the process heat and electricity produced by a 600 MWt MHR. This paper describes RELAP5-3D analyses performed to evaluate alternative primary system cooling configurations for the MHR to minimize peak reactor vessel and core temperatures while achieving core helium outlet temperatures in the range of 900 oC to 1000 oC, needed for the efficient production of hydrogen using either the S-I thermochemical or HTE process. The cooling schemes investigated are intended to ensure peak fuel temperatures do not exceed specified limits under normal or transient upset conditions, and that reactor vessel temperatures do not exceed ASME code limits for steady-state or transient conditions using standard LWR vessel materials. Preconceptual designs for both an S-I thermochemical and HTE hydrogen production plant driven by a 600 MWt MHR at helium outlet temperatures in the range of 900 oC to 1000 oC are described and compared. An initial SAPHIRE model to evaluate the reliability, maintainablility, and availability of the S-I hydrogen production plant is also discussed, and plans for future assessments of conceptual designs for both a S-I thermochemical and HTE hydrogen production plant coupled to a 600 MWt modular helium reactor are described.

E. A. Harvego; S. M. Reza; M. Richards; A. Shenoy

2005-05-01T23:59:59.000Z

96

The Helium spectrum in erupting solar prominences  

E-Print Network (OSTI)

Even quiescent solar prominences may become active and sometimes erupt. These events are occasionally linked to coronal mass ejections. However we know very little about the plasma properties during the activation and eruption processes. We present new computations of the helium line profiles emitted by an eruptive prominence. The prominence is modelled as a plane-parallel slab standing vertically above the solar surface and moving upward as a solid body. The helium spectrum is computed with a non local thermodynamic equilibrium radiative transfer code. The effect of Doppler dimming / brightening is investigated in the resonance lines of He I and He II formed in the EUV, as well as on the He I 10830 A and 5876 A lines. We focus on the line profile properties and the resulting integrated intensities. It is shown that the helium lines are very sensitive to Doppler dimming effects. We also study the effect of frequency redistribution in the formation mechanisms of the resonance lines and find that it is necessary to use partial redistribution in frequency for the resonance lines.

Nicolas Labrosse; Pierre Gouttebroze; Jean-Claude Vial

2006-09-18T23:59:59.000Z

97

A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal  

Open Energy Info (EERE)

Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal System Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal System Details Activities (3) Areas (1) Regions (0) Abstract: Fluids from springs, fumaroles, and wells throughout Dixie Valley, NV were analyzed for noble gas abundances and isotopic compositions. The helium isotopic compositions of fluids produced from the Dixie Valley geothermal field range from 0.70 to 0.76 Ra, are among the highest values in the valley, and indicate that similar to 7.5% of the total helium is derived from the mantle. A lack of recent volcanics or other potential sources requires flow of mantle-derived helium up along the

98

The influence of cracks in rotating shafts  

E-Print Network (OSTI)

In this paper, the influence of transverse cracks in a rotating shaft is analysed. The paper addresses the two distinct issues of the changes in modal properties and the influence of crack breathing on dynamic response during operation. Moreover, the evolution of the orbit of a cracked rotor near half of the first resonance frequency is investigated. The results provide a possible basis for an on-line monitoring system. In order to conduct this study, the dynamic response of a rotor with a breathing crack is evaluated by using the alternate frequency/time domain approach. It is shown that this method evaluates the nonlinear behaviour of the rotor system rapidly and efficiently by modelling the breathing crack with a truncated Fourier series. The dynamic response obtained by applying this method is compared with that evaluated through numerical integration. The resulting orbit during transient operation is presented and some distinguishing features of a cracked rotor are examined.

Jean-Jacques Sinou; A. W. Lees

2008-01-19T23:59:59.000Z

99

The Potential of Helium as a Guide to Uranium Ore  

Science Conference Proceedings (OSTI)

Martin Marietta Corp. and Earth Sciences, Inc., studied the effectiveness of helium surveying as a tool for uranium exploration. They generated basic data on the little-known distribution of helium in soils, tested various techniques for conducting surveys in the field, developed guidelines for helium surveys and interpretation, and stimulated interest, if it was warranted, in the further testing and application of promising approaches.

1978-07-01T23:59:59.000Z

100

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal...  

Open Energy Info (EERE)

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon- Evidence For Renewed Volcanic Activity Or A Long Term Steady State...

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

The Helium-3 Supply Crisis – Alternative Techniques to ...  

Science Conference Proceedings (OSTI)

... Helium-3 is a by-product of tritium decay after 12 years. Due to the nonetheless encouraging reduction in stocks of tritium ...

2010-04-16T23:59:59.000Z

102

NIST Studies How New Helium Ion Microscope Measures Up  

Science Conference Proceedings (OSTI)

... are studying helium ion microscopes to improve ... analogous to the scanning electron microscope, which was ... are far larger than electrons, they can ...

2012-11-02T23:59:59.000Z

103

Regional And Local Trends In Helium Isotopes, Basin And Range...  

Open Energy Info (EERE)

Superimposed on this general regional trend are isolated features with elevated helium isotope ratios (0.8-2.1 Ra) compared to the local background. Spring geochemistry and...

104

The effect of hydrogen isotopes and helium on the tensile properties of 21-6-9 stainless steel  

DOE Green Energy (OSTI)

High-energy-rate-forged (HERF) stainless steels are used as the materials of construction for pressure vessels designed for the containment of hydrogen and its isotopes. Hydrogen and helium, the decay product of tritium, are known to embrittle these materials. HERF stainless steels have a relatively good resistance to hydrogen-and-helium-induced embrittlement when compared to annealed stainless steels due to their high number density of dislocations, which act as traps for hydrogen and helium. However, the degree of embrittlement in these materials can vary considerably because of microstructure and yield strength variations introduced during the forging process. In this study the effect of hydrogen and tritium on the tensile properties of 21-6-9 stainless steel was measured as a function of HERF yield strength in the range of 660 to 930 MPa. The effect of microstructure was studied also be conducting tensile tests with HERF and annealed samples.

Morgan, M.J.; Lohmeier, D.

1990-12-31T23:59:59.000Z

105

The effects of hydrogen isotopes and helium on the tensile properties of 21-6-9 stainless steel  

DOE Green Energy (OSTI)

High-energy-rate-forged (HERF) stainless steels are used as the materials of construction for tritium and deuterium reservoirs. Hydrogen and helium, the decay product of tritium, are known to embrittle stainless steels (1--4). The resistance to hydrogen and helium induced embrittlement is relatively good for HERF stainless steels when compared to annealed stainless steels due to their high number density of dislocations, which act as traps for hydrogen and helium. However, the degree of the embrittlement in these materials can vary considerably because of microstructure and yield strength variations introduced during the forging process. In this study the effect of hydrogen and tritium on the room temperature tensile properties of 21-6-9 stainless steel was measured as a function of HERF yield strength in the range of 500 to 918 MPa. The effect of a microstructures was studied also by conducting tensile tests with both HERF samples and annealed samples.

Morgan, M.J.

1990-12-31T23:59:59.000Z

106

The effect of hydrogen isotopes and helium on the tensile properties of 21-6-9 stainless steel  

DOE Green Energy (OSTI)

High-energy-rate-forged (HERF) stainless steels are used as the materials of construction for pressure vessels designed for the containment of hydrogen and its isotopes. Hydrogen and helium, the decay product of tritium, are known to embrittle these materials. HERF stainless steels have a relatively good resistance to hydrogen-and-helium-induced embrittlement when compared to annealed stainless steels due to their high number density of dislocations, which act as traps for hydrogen and helium. However, the degree of embrittlement in these materials can vary considerably because of microstructure and yield strength variations introduced during the forging process. In this study the effect of hydrogen and tritium on the tensile properties of 21-6-9 stainless steel was measured as a function of HERF yield strength in the range of 660 to 930 MPa. The effect of microstructure was studied also be conducting tensile tests with HERF and annealed samples.

Morgan, M.J.; Lohmeier, D.

1990-01-01T23:59:59.000Z

107

Stress Corrosion Cracking - Programmaster.org  

Science Conference Proceedings (OSTI)

Oct 28, 2013 ... Atomic Ordering in Alloy 690 and Its Effect on Long-term Structural Stability and Stress Corrosion Cracking Susceptibility: Michael Kaufman1; ...

108

Creep Crack Growth Behaviour of Alloy 718  

Science Conference Proceedings (OSTI)

its creep crack growth is controlled by stress intensity factor regardless of load level .... energy. Since vacancies diffuse from a low strain energy position to a high ...

109

Quench Cracking Characterization of Superalloys Using Fracture ...  

Science Conference Proceedings (OSTI)

When the on-cooling thermal stress. (load) accumulated to a certain point, quench cracking happened abruptly. Based on the precrack length, the thermal stress ...

110

Evaluation of Stress-Corrosion Cracking  

Science Conference Proceedings (OSTI)

Table 3   Stress-corrosion cracking of selected material systems...chlorides, seawater Oil/gas production and transmission, oil refining,

111

Crystallographic Orientation Dependence of Fatigue Crack ...  

Science Conference Proceedings (OSTI)

In the present study, fatigue crack propagation behavior of rolled AZ31B magnesium ... Alloy Design for Enhancing the Fracture Resistance of Heat Treated High ...

112

Sulfide Stress Cracking in Steels - A Review  

Science Conference Proceedings (OSTI)

Symposium, Corrosion and Corrosion Protection of Materials in the Oil and Gas Industry. Presentation Title, Sulfide Stress Cracking in Steels - A Review.

113

Environmentally Assisted Cracking Susceptibility Assessment of AP ...  

Science Conference Proceedings (OSTI)

Presentation Title, Environmentally Assisted Cracking Susceptibility Assessment of AP 1000 Reactor Coolant Pump Flywheel Retainer Ring A289 18Cr-18Mn ...

114

Discontinuous surface cracks during stress corrosion cracking of stainless steel single crystal  

E-Print Network (OSTI)

Discontinuous surface cracks during stress corrosion cracking of stainless steel single crystal L Keywords: A. Stainless steel B. SEM C. Stress corrosion a b s t r a c t Single crystal 321 stainless steel, and the river-markings exhibited microshear facets along the {1 1 1} plane. Interaction between the main crack

Volinsky, Alex A.

115

Simulation program for central helium liquefier  

SciTech Connect

The computer program described here analyzes the performance of Fermilab Central Helium Liquefier (CHL) and predicts the values of the plant thermodynamic variables at all process points in the plant. To simulate CHL, this program is modified from the prototype program which was developed by Hitachi Ltd. a couple of years ago. This program takes care of only the steady state simulation and takes account of the change of the turbine efficiency, the pressure drops and the UA values of the heat exchangers. How to use the program is shown.

Kawamura, S.

1984-02-20T23:59:59.000Z

116

Assessment of methods for analyzing gaseous mixtures of hydrogen isotopes and helium  

DOE Green Energy (OSTI)

Mass spectrographic methods have served well in the past to analyze gaseous mixtures of the hydrogen isotopes. Alternate methods of analyses are reviewed which offer wider ranges and variety of isotopic determinations. This report describes possible improvements of the mass spectrographic determinations, gas chromatography, anti-Stokes Raman spectroscopy, microwave-induced optical emission spectroscopy, and methods of measuring tritium using radiation detection devices. Precision, accuracy, limitations, and costs are included for some of the methods mentioned. Costs range from $70,000 for the anti-Stokes Raman spectroscopy equipment, which can determine hydrogen isotopes but not helium, to less than $10,000 for the gas chromatographic equipment, which can determine hydrogen isotopes and helium with precision and accuracy comparable to those of the mass spectrometer.

Attalla, A.; Bishop, C.T.; Bohl, D.R.; Buxton, T.L.; Sprague, R.E.; Warner, D.K.

1976-10-20T23:59:59.000Z

117

Liquid uranium alloy-helium fission reactor  

DOE Patents (OSTI)

This invention describes a nuclear fission reactor which has a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200 to 1800/sup 0/C range, and even higher to 2500/sup 0/C.

Minkov, V.

1984-06-13T23:59:59.000Z

118

Liquid uranium alloy-helium fission reactor  

SciTech Connect

This invention teaches a nuclear fission reactor having a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200.degree.-1800.degree. C. range, and even higher to 2500.degree. C., limited only by the thermal effectiveness of the structural materials, increasing the efficiency of power generation from the normal 30-35% with 300.degree.-500.degree. C. upper limit temperature to 50-65%. Irradiation of the circulating liquid fuel, as contrasted to only localized irradiation of a solid fuel, provides improved fuel utilization.

Minkov, Vladimir (Skokie, IL)

1986-01-01T23:59:59.000Z

119

DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI  

SciTech Connect

A direct measure of the helium abundances from the near-infrared transition of He I at 1.08 {mu}m is obtained for two nearly identical red giant stars in the globular cluster Omega Centauri. One star exhibits the He I line; the line is weak or absent in the other star. Detailed non-local thermal equilibrium semi-empirical models including expansion in spherical geometry are developed to match the chromospheric H{alpha}, H{beta}, and Ca II K lines, in order to predict the helium profile and derive a helium abundance. The red giant spectra suggest a helium abundance of Y {<=} 0.22 (LEID 54064) and Y = 0.39-0.44 (LEID 54084) corresponding to a difference in the abundance {Delta}Y {>=} 0.17. Helium is enhanced in the giant star (LEID 54084) that also contains enhanced aluminum and magnesium. This direct evaluation of the helium abundances gives observational support to the theoretical conjecture that multiple populations harbor enhanced helium in addition to light elements that are products of high-temperature hydrogen burning. We demonstrate that the 1.08 {mu}m He I line can yield a helium abundance in cool stars when constraints on the semi-empirical chromospheric model are provided by other spectroscopic features.

Dupree, A. K.; Avrett, E. H., E-mail: dupree@cfa.harvard.edu, E-mail: eavrett@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2013-08-20T23:59:59.000Z

120

3:2:1 Crack Spread  

Gasoline and Diesel Fuel Update (EIA)

:2:1 Crack Spread :2:1 Crack Spread Figure 1 Source: U.S. Energy Information Administration, based on Thomson Reuters. A crack spread measures the difference between the purchase price of crude oil and the selling price of finished products, such as gasoline and distillate fuel, that a refinery produces from the crude oil. Crack spreads are an indicator of the short-term profit margin of oil refineries because they compare the cost of the crude oil inputs to the wholesale, or spot, prices of the outputs (although they do not include other variable costs or any fixed costs). The 3:2:1 crack spread approximates the product yield at a typical U.S. refinery: for every three barrels of crude oil the refinery processes, it makes two barrels of gasoline and one barrel of distillate

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Characterization of Environment-Dependent Fatigue Crack Growth ...  

Science Conference Proceedings (OSTI)

at high frequency levels to fully environment-dependent at very low frequency ... environment-dependent crack growth process, crack increment per cycle is ...

122

Computational Weld Mechanics of Hot Crack Nucleation in Nickel ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Computational weld mechanics (CWM) is used to estimate the likelihood of hot crack nucleation in a welded joint. A hot crack nucleates when ...

123

The Effect of Microstructure on the Fatigue Crack Growth Resistance ...  

Science Conference Proceedings (OSTI)

GROWTH RESISTANCE OF NICKEL BASE SUF'RRALLOYS. Randy Bowman ... damage are most resistant to crack growth. ... crack propagation. (FCP) was ...

124

High cycle fatigue and fatigue crack propagation behavior of ...  

Science Conference Proceedings (OSTI)

And fatigue crack propagation rates of modified A7075 showed slightly lower. Those superior fatigue strength and resistance of fatigue crack propagation of ...

125

Characterization of Elevated Temperature Fatigue Crack Growth Rates  

Science Conference Proceedings (OSTI)

temperature fatigue and the crack growth rates may be adequately correlated with the ... During creep crack growth the use of rate dependent elastic/plastic frac-.

126

Enhanced heat extraction from hot-dry-rock geothermal reservoirs due to interacting secondary thermal cracks. Final report  

DOE Green Energy (OSTI)

How the fluid circulating through the main hydraulic fracture and the thermally-induced secondary, growing, interacting cracks affects the time-varying temperature, deformations, stresses, thermal crack geometry, water flow rates through the main and thermal cracks, reservoir coolant outlet temperature, and reservoir thermal power of the cracked geothermal reservoir is investigated. First, a simplified version of the proposed hot-dry-rock reservoir is considered. A closed-form solution of the rock temperature without thermal crack was found and substituted into SAP-IV computer code to calculate the stresses. These stresses being superposed with earth stresses and fluid pressure were used in conjunction with the fracture mechanics criterion to determine the initiation of secondary thermal crack. After the initiation of secondary thermal crack, the rock temperature was then calculated by a two-dimensional heat conduction program AYER. The detailed procedures for carrying out these steps are listed. Solutions developed are applied to studying the time-varying temperature field, thermal stresses and crack geometry produced, and additional heat power generated in the reservoir. Conclusions were discussed and summarized. (MHR)

Hsu, Y.C.

1979-04-01T23:59:59.000Z

127

Some mechanistic observations on the crack growth characteristics of pressure vessel and piping steels in PWR environment  

SciTech Connect

The fatigue crack growth behavior of A533B and A508 pressure vessel steel and AISI Types 304 and 316 steels used in reactor coolant piping have been studied in a pressurized water reactor environment at 288/sup 0/C (550/sup 0/F). The influence of stress ratio (P/sub min//P/sub max/), frequency, ramp times, specimen orientation and material microstructures were included in the study. While none of the materials showed evidence of static crack growth in the environment, the ferritic steels did show an enhanced fatigue crack growth rate at test frequencies of five cycles per minute and lower. Based on fractographic examinations the enhanced growth rate is not the result of environmentally induced intergranular or cleavage modes of crack propagation. Instead, striation spacing measurements were found to agree with the macroscopic crack growth rate, demonstrating a time dependent environmental interaction which introduces a frequency dependent enhancement of the mechanically developed striations. Crack growth experiments using hold times have confirmed the absence of any superimposed contribution of static crack growth components. Fatigue crack growth tests were conducted in an environment of Hydrogen Sulfide gas to establish the contribution of hydrogen embrittlement and will also be described.

Bamford, W.H.; Moon, D.M.

1979-01-01T23:59:59.000Z

128

Superconducting cable cooling system by helium gas and a mixture of gas and liquid helium  

DOE Patents (OSTI)

Thermally contacting, oppositely streaming cryogenic fluid streams in the same enclosure in a closed cycle that changes from a cool high pressure helium gas to a cooler reduced pressure helium fluid comprised of a mixture of gas and boiling liquid so as to be near the same temperature but at different pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T.sub.1. By first circulating the fluid in a go leg from a refrigerator at one end of the line as a high pressure helium gas near the normal boiling temperature of helium; then circulating the gas through an expander at the other end of the line where the gas becomes a mixture of reduced pressure gas and boiling liquid at its boiling temperature; then by circulating the mixture in a return leg that is separated from but in thermal contact with the gas in the go leg and in the same enclosure therewith; and finally returning the resulting low pressure gas to the refrigerator for compression into a high pressure gas at T.sub.2 is a closed cycle, where T.sub.1 >T.sub.2, the temperature distribution is such that the line temperature is nearly constant along its length from the refrigerator to the expander due to the boiling of the liquid in the mixture. A heat exchanger between the go and return lines removes the gas from the liquid in the return leg while cooling the go leg.

Dean, John W. (Los Alamos, NM)

1977-01-01T23:59:59.000Z

129

Testing CPT Invariance with Antiprotonic Helium Atoms  

Science Conference Proceedings (OSTI)

The structure of matter is related to symmetries at every level of study. CPT symmetry is one of the most important laws of field theory: it states the invariance of physical properties when one simultaneously changes the signs of the charge and of the spatial and time coordinates of free elementary particles. Although in general opinion CPT symmetry is not violated in Nature, there are theoretical attempts to develop CPT-violating models. The Antiproton Decelerator at CERN has been built to test CPT invariance. The ASACUSA experiment compares the properties of particles and antiparticles by studying the antiprotonic helium atom via laser spectroscopy and measuring the mass, charge and magnetic moment of the antiproton as compared to those of the proton.

Horvath, Dezso [KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, Hungary and Institute of Nuclear Research (ATOMKI), Debrecen (Hungary)

2008-08-08T23:59:59.000Z

130

Compact hydrogen/helium isotope mass spectrometer  

DOE Patents (OSTI)

The compact hydrogen and helium isotope mass spectrometer of the present invention combines low mass-resolution ion mass spectrometry and beam-foil interaction technology to unambiguously detect and quantify deuterium (D), tritium (T), hydrogen molecule (H.sub.2, HD, D.sub.2, HT, DT, and T.sub.2), .sup.3 He, and .sup.4 He concentrations and concentration variations. The spectrometer provides real-time, high sensitivity, and high accuracy measurements. Currently, no fieldable D or molecular speciation detectors exist. Furthermore, the present spectrometer has a significant advantage over traditional T detectors: no confusion of the measurements by other beta-emitters, and complete separation of atomic and molecular species of equivalent atomic mass (e.g., HD and .sup.3 He).

Funsten, Herbert O. (Los Alamos, NM); McComas, David J. (Los Alamos, NM); Scime, Earl E. (Morgantown, WV)

1996-01-01T23:59:59.000Z

131

ACOUSTIC SIGNATURES OF THE HELIUM CORE FLASH  

SciTech Connect

All evolved stars with masses M {approx}< 2 M{sub Sun} undergo an initiating off-center helium core flash in their M{sub c} Almost-Equal-To 0.48 M{sub Sun} He core as they ascend the red giant branch (RGB). This off-center flash is the first of a few successive helium shell subflashes that remove the core electron degeneracy over 2 Myr, converting the object into a He-burning star. Though characterized by Thomas over 40 years ago, this core flash phase has yet to be observationally probed. Using the Modules for Experiments in Stellar Astrophysics (MESA) code, we show that red giant asteroseismology enabled by space-based photometry (i.e., Kepler and CoRoT) can probe these stars during the flash. The rapid ({approx}< 10{sup 5} yr) contraction of the red giant envelope after the initiating flash dramatically improves the coupling of the p-modes to the core g-modes, making the detection of l = 1 mixed modes possible for these 2 Myr. This duration implies that 1 in 35 stars near the red clump in the H-R diagram will be in their core flash phase. During this time, the star has a g-mode period spacing of {Delta}P{sub g} Almost-Equal-To 70-100 s, lower than the {Delta}P{sub g} Almost-Equal-To 250 s of He-burning stars in the red clump, but higher than the RGB stars at the same luminosity. This places them in an underpopulated part of the large frequency spacing ({Delta}{nu}) versus {Delta}P{sub g} diagram that should ease their identification among the thousands of observed red giants.

Bildsten, Lars; Paxton, Bill; Moore, Kevin; Macias, Phillip J. [Kavli Institute for Theoretical Physics and Department of Physics Kohn Hall, University of California, Santa Barbara, CA 93106 (United States)

2012-01-15T23:59:59.000Z

132

Numerical modeling of crack reorientation and link-up  

Science Conference Proceedings (OSTI)

The FRANC3D/BES software system has been used to simulate the reorientation and link-up of hydraulic fractures in three-dimensional (3D) problems. The adopted technique only needs to discretize the body surface and the crack surface. The crack propagation ... Keywords: FRANC3D/BES, crack propagation, multiple cracks

C. Y. Dong; C. J. de Pater

2002-11-01T23:59:59.000Z

133

Evolution of the Standard Helium Liquefier and Refrigerator Range designed by Air Liquide DTA, France  

E-Print Network (OSTI)

Evolution of the Standard Helium Liquefier and Refrigerator Range designed by Air Liquide DTA, France

Crispel, S; Caillaud, A; Delcayre, F; Grabie, V

2008-01-01T23:59:59.000Z

134

Transient Behaviour and Helium Discharge in Cryogenic Distribution Line (QRL) Headers Following Breakdown of Insulation Vacuum  

E-Print Network (OSTI)

Transient Behaviour and Helium Discharge in Cryogenic Distribution Line (QRL) Headers Following Breakdown of Insulation Vacuum

Chorowski, M

1997-01-01T23:59:59.000Z

135

Optimal control of fluid catalytic cracking processes  

Science Conference Proceedings (OSTI)

An investigation was made of the applicability of optimal control theory to the design of control systems for non-linear, multivariable chemical processes. A hypothetical fluid catalytic cracking process was selected as a typical representative of such ...

L. A. Gould; L. B. Evans; H. Kurihara

1970-09-01T23:59:59.000Z

136

Imprinting the memory into paste and its visualization as crack patterns in drying process  

E-Print Network (OSTI)

In the drying process of paste, we can imprint into the paste the order how it should be broken in the future. That is, if we vibrate the paste before it is dried, it remembers the direction of the initial external vibration, and the morphology of resultant crack patterns is determined solely by the memory of the direction. The morphological phase diagram of crack patterns and the rheological measurement of the paste show that this memory effect is induced by the plasticity of paste.

Akio Nakahara; Yousuke Matsuo

2005-01-19T23:59:59.000Z

137

SRS upgrades helium recovery system | National Nuclear Security  

NLE Websites -- All DOE Office Websites (Extended Search)

upgrades helium recovery system | National Nuclear Security upgrades helium recovery system | National Nuclear Security Administration Our Mission Managing the Stockpile Preventing Proliferation Powering the Nuclear Navy Emergency Response Recapitalizing Our Infrastructure Continuing Management Reform Countering Nuclear Terrorism About Us Our Programs Our History Who We Are Our Leadership Our Locations Budget Our Operations Media Room Congressional Testimony Fact Sheets Newsletters Press Releases Speeches Events Social Media Video Gallery Photo Gallery NNSA Archive Federal Employment Apply for Our Jobs Our Jobs Working at NNSA Blog Home > NNSA Blog > SRS upgrades helium recovery system SRS upgrades helium recovery system Posted By Office of Public Affairs Savannah River Site (SRS) Tritium Programs recently completed a project to design, build and relocate a new system for separating and capturing

138

The Liquefaction of Hydrogen and Helium Using Small Coolers  

E-Print Network (OSTI)

because the J-T valve and heat exchanger clogged because ofseparate J-T valve and J-T heat exchanger had to be used. Itadded J-T circuit and heat exchanger, to liquefy helium have

Green, Michael A.

2006-01-01T23:59:59.000Z

139

Helium Pumping Wall for a Liquid Lithium Tokamak Richard Majeski...  

NLE Websites -- All DOE Office Websites (Extended Search)

is that a permeable wall is used to separate out helium produced as ash by a burning fusion reactor. This would replace the divertor structure and associated pumps in a...

140

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs,  

Open Energy Info (EERE)

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon- Evidence For Renewed Volcanic Activity Or A Long Term Steady State System(Question) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon- Evidence For Renewed Volcanic Activity Or A Long Term Steady State System(Question) Details Activities (1) Areas (1) Regions (0) Abstract: Here we present the helium and carbon isotope results from the initial study of a fluid chemistry-monitoring program started in the summer of 2001 near the South Sister volcano in central Oregon. The Separation Creek area which is several miles due west of the volcano is the locus of

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Operations aspects of the Fermilab Central Helium Liquefier Facility  

SciTech Connect

The Fermilab Central Helium Liquefier (CHL) facility consists of helium and nitrogen reliquefier plants operated 24 hours-a-day to supply LHe at 4.6{degrees}K and LN{sub 2} for the Fermilab Tevatron superconducting proton-antiproton collider ring and to recover warm return gases. Operating aspects of CHL, including different equipment and systems reliability, availability, maintenance experience, safety concerns, and economics aspects are discussed.

Geynisman, M.G.; Makara, J.N.

1995-03-01T23:59:59.000Z

142

Operations aspects of the Fermilab Central Helium Liquefier facility  

SciTech Connect

The Fermilab Central Helium Liquefier (CHL) facility consists of helium and nitrogen reliquefier plants operated 24 hours-a-day to supply LHe at 4.6 K and LN{sub 2} for the Fermilab Tevatron superconducting proton-antiproton collider ring and to recover warm return gases. Operating aspects of CHL, including different equipment and systems reliability, availability, maintenance experience, safety concerns, and economics aspects are discussed.

Geynisman, M.G.; Makara, J.N.

1996-09-01T23:59:59.000Z

143

Recovery of purified helium or hydrogen from gas mixtures  

DOE Patents (OSTI)

A process is described for the removal of helium or hydrogen from gaseous mixtures also containing contaminants. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatomspheric pressure to preferentially absorb the contaminants in the fluorocarbon. Unabsorbed gas enriched in hydrogen or helium is withdrawn from the absorption zone as product. Liquid fluorocarbon enriched in contaminants is withdrawn separately from the absorption zone. (10 claims)

Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

1974-01-15T23:59:59.000Z

144

Environmentally assisted cracking in light water reactors.  

DOE Green Energy (OSTI)

This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from January to December 2002. Topics that have been investigated include: (a) environmental effects on fatigue crack initiation in carbon and low-alloy steels and austenitic stainless steels (SSs), (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic SSs in BWRs, (c) evaluation of causes and mechanisms of irradiation-assisted cracking of austenitic SS in PWRs, and (d) cracking in Ni-alloys and welds. A critical review of the ASME Code fatigue design margins and an assessment of the conservation in the current choice of design margins are presented. The existing fatigue {var_epsilon}-N data have been evaluated to define the effects of key material, loading, and environmental parameters on the fatigue lives of carbon and low-alloy steels and austenitic SSs. Experimental data are presented on the effects of surface roughness on fatigue crack initiation in these materials in air and LWR environments. Crack growth tests were performed in BWR environments on SSs irradiated to 0.9 and 2.0 x 10{sup 21} n x cm{sup -2}. The crack growth rates (CGRs) of the irradiated steels are a factor of {approx}5 higher than the disposition curve proposed in NUREG-0313 for thermally sensitized materials. The CGRs decreased by an order of magnitude in low-dissolved oxygen (DO) environments. Slow-strain-rate tensile (SSRT) tests were conducted in high-purity 289 C water on steels irradiated to {approx}3 dpa. The bulk S content correlated well with the susceptibility to intergranular SCC in 289 C water. The IASCC susceptibility of SSs that contain >0.003 wt. % S increased drastically. bend tests in inert environments at 23 C were conducted on broken pieces of SSRT specimens and on unirradiated specimens of the same materials after hydrogen charging. The results of the tests and a review of other data in the literature indicate that IASCC in 289 C water is dominated by a crack-tip grain-boundary process that involves S. An initial IASCC model has been proposed. A crack growth test was completed on mill annealed Alloy 600 in high-purity water at 289 C and 320 C under various environmental and loading conditions. The results from this test are compared with data obtained earlier on several other heats of Alloy 600.

Chopra, O. K.; Chung, H. M.; Clark, R. W.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.; Strain, R. V.

2007-11-06T23:59:59.000Z

145

Effect of Hot Cracks on EAC Crack Initiation and Growth in Nickel ...  

Science Conference Proceedings (OSTI)

No crack initiation/extension from hot cracks occured in any weld metals, which is ... Applicability of Lean Grade of Duplex Stainless Steels in Nuclear Power Plants .... Wear of Zircaloy-4 Grid Straps Due to Fretting and Periodic Impact with RV ...

146

TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW  

SciTech Connect

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.

Langton, C.

2012-05-11T23:59:59.000Z

147

Acoustic Emission and Guided Wave Monitoring of Fatigue Crack Growth on a Full Pipe Specimen  

Science Conference Proceedings (OSTI)

Continuous on-line monitoring of active and passive systems, structures and components in nuclear power plants will be critical to extending the lifetimes of nuclear power plants in the US beyond 60 years. Acoustic emission and guided ultrasonic waves are two tools for continuously monitoring passive systems, structures and components within nuclear power plants and are the focus of this study. These tools are used to monitor fatigue damage induced in a SA 312 TP304 stainless steel pipe specimen. The results of acoustic emission monitoring indicate that crack propagation signals were not directly detected. However, acoustic emission monitoring exposed crack formation prior to visual confirmation through the detection of signals caused by crack closure friction. The results of guided ultrasonic wave monitoring indicate that this technology is sensitive to the presence and size of cracks. The sensitivity and complexity of GUW signals is observed to vary with respect to signal frequency and path traveled by the guided ultrasonic wave relative to the crack orientation.

Meyer, Ryan M.; Cumblidge, Stephen E.; Ramuhalli, Pradeep; Watson, Bruce E.; Doctor, Steven R.; Bond, Leonard J.

2011-05-06T23:59:59.000Z

148

STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS  

SciTech Connect

Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.

Lam, P; Philip Zapp, P; Jonathan Duffey, J; Kerry Dunn, K

2009-05-01T23:59:59.000Z

149

Stress Corrosion Cracking Behavior of Cast Stainless Steels  

SciTech Connect

Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not detrimental to SCC resistance.

Teysseyre, Sebastien [University of Michigan; Busby, Jeremy T [ORNL; Was, Gary [University of Michigan

2009-01-01T23:59:59.000Z

150

Adsorbent-treated cat cracked gasoline in motor fuels  

SciTech Connect

A methof is described for supressing carburetor deposit formation of motor fuels containing untreated cat cracked gasoline by blending adsorbent-treated cat cracked gasoline into the motor fuel. Up to about 50 percent by weight of the total composition is adsorbent treated cat cracked gasoline, but preferably from about 5 to about 25 percent by weight of the total composition is adsorbent treated cat cracked gasoline. In a preferred embodiment a standard reference fuel capable of providing a predetermined level of carburetor deposit formation is provided by the addition of either adsorbent-treated cat cracked gasoline, untreated cat cracked gasoline, or aromatic amines to a base fuel.

Thomas, S.P.

1980-09-30T23:59:59.000Z

151

Crack detection using resonant ultrasound spectroscopy  

DOE Patents (OSTI)

This invention is comprised of a method and apparatus 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.

Migliori, A.; Bell, T.M.

1992-12-31T23:59:59.000Z

152

David Lee, Douglas Osheroff, Superfluidity, and Helium 3  

NLE Websites -- All DOE Office Websites (Extended Search)

David Lee, Douglas Osheroff, Superfluidity, and Helium 3 David Lee, Douglas Osheroff, Superfluidity, and Helium 3 Resources with Additional Information David M. Lee and Douglas D. Osheroff received the 1996 Nobel Prize in Physics for 'their discovery of superfluidity in helium-3'. "In 1976, Lee shared with Richardson and Osheroff their earliest recognition for studies of superfluidity, the Simon Memorial Prize of the British Physical Society. The Buckley Prize of the American Physical Society followed for the trio in 1981. ... Douglas D. Osheroff Douglas D. Osheroff Courtesy AIP Emilio Segrè Visual Archives, AIP Meggers Gallery of Nobel Laureates David Lee David M. Lee Photo by Janerik Henriksson, Courtesy AIP Emilio Segrè Visual Archievs, W.F. Meggers Gallery of Nobel Laureate From 1966-67, Lee was a visiting scientist at Brookhaven National Laboratory ... ."1 His research at Cornell University includes " Low Temperature Physics: Normal and superfluid 3He, studies of the orientation of solid helium by optical birefringence, solid 3He and 4He, lambda phase diagram of 3He - 4He mixtures, quasiparticle tunneling in superconductors, magnetic resonance and ultrasound techniques, cooling by adiabatic demagnetization and the Pomeranchuk technique, spin waves in spin polarized hydrogen gas, high concentrations of hydrogen and nitrogen atons via matrix isolation by impurity-helium solids, magnetism, electron spin resonance."2

153

Residual stresses and stress corrosion cracking in pipe fittings  

Science Conference Proceedings (OSTI)

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.

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

1994-06-01T23:59:59.000Z

154

Temperature and environmentally assisted cracking in low alloy steel  

Science Conference Proceedings (OSTI)

Environmental assisted cracking (EAC) can be defined as the propagation of fatigue cracks in water at rates from 3 to over 40 times the growth rates in air. For low alloy steels with sulfur contents > 0.0125% by weight, EAC is normal behavior in the 240 to 290C range. However, literature yields mixed results for low alloy steels with compositions just below this sulfur level; some reports indicate EAC while others do not. Also, several authors have reported an increased tendency toward EAC when the water temperatures were lowered. In the present work, five ASTM A 508 Class 2 forgings with ladle and check analyses that ranged from 0.010 to 0.019 wt% S were tested in high purity deaerated water in the temperature range of 93 to 260C. At 260C these forgings did not exhibit EAC, reinforcing earlier results for two similar forgings. This broad sampling indicates strong resistance to EAC for this class of forging at 260C. On the other hand, EAC occurred consistently in the three of these forgings that were tested below 204C, provided the test conditions (loading frequency, {Delta}K, and R) were high enough to produce a high baseline fatigue crack growth rate (FCGR), where the baseline FCGR is that expected in air. At 149C, EAC occurred at test conditions that combined to yield a baseline FCGR greater than {approx}2E-6 mm/s. At 204, 121, and 93C, this critical crack growth rate appeared to shift to lower baseline values. The EAC that occurred at lower temperatures was a factor of 3 to 12 times higher than baseline air rates, which was not as strong as the effect for higher sulfur steels at 240 to 290C. Also, no plateau in the growth rates occurred as it does with the higher sulfur steels. In another approach, EAC was induced at 93 and at 260C by raising the dissolved oxygen content of the water from 15 ppb.

Auten, T.A.; Monter, J.V.

1995-04-01T23:59:59.000Z

155

The study of stress application and corrosion cracking on Ni?16 Cr?9 Fe (Alloy 600) C-ring samples by polychromatic X-ray microdiffraction  

SciTech Connect

Microscopic strains associated with stress corrosion cracks have been investigated in stressed C-rings of Ni-16 Cr-9 Fe (Alloy 600) boiler tubing. Polychromatic X-ray microdiffraction was used to measure deviatoric strain tensors and the distribution of dislocations near cracks that had been propagated in electrochemically accelerated corrosion tests. An associated investigation of the C-ring-induced strains prior to corrosion showed significant tensile strain in the stress axis direction by the torsional closure of the alloy tube section in the C-ring test. Significant grain lattice rotation and pronounced plastic strain at some grain boundaries were noted. Stress-corrosion-cracking-generated intergranular cracks were produced in two Alloy 600 specimens after 6 h and 18 h tests. The diffraction patterns and resultant strain tensors were mapped around the cracked area to a 1 {mu}m spatial resolution. The strain tensor transverse to the crack growth direction showed tensile strain at the intergranular region just ahead of the crack tip for both specimens. Both cracks were found to follow grain boundary pathways that had the lowest angle of misorientation. Dislocation distributions within each grain were qualitatively obtained from the shapes of the diffraction spots and the effect of 'hard' and 'soft' grains on the crack pathway was explored for both 6 h and 18 h specimens. The Schmid factor of one of the grains adjacent to the crack at the 6 h and 18 h initiation sites was found to be the lowest, compared to Schmid factors calculated for surface grains away from the initiation site, and also along the crack path into the bulk.

Chao, Jing; Fuller, Marina L.Suominen; McIntyre, N. Stewart; Carcea, Anatolie G.; Newman, Roger C.; Kunz, Martin; Tamura, Nobumichi (Toronto); (UWO); (LBNL)

2012-03-27T23:59:59.000Z

156

Corrosion fatigue crack growth in clad low-alloy steel. Part 2, Water flow rate effects in high sulfur plate steel  

Science Conference Proceedings (OSTI)

Corrosion fatigue crack propagation tests were conducted on a high- sulfur ASTM A302-B plate steel overlaid with weld-deposited Alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 22.8--27.3 mm, and depths of 10.5--14.1 mm. The experiments were initiated in a quasi-stagnant low-oxygen (O{sub 2} < 10 ppb) aqueous environment at 243{degrees}C, under loading conditions ({Delta}K, R, cyclic frequency) conducive to environmentally-assisted cracking (EAC) under quasi-stagnant conditions. Following fatigue testing under quasi-stagnant conditions where EAC was observed, the specimens were then fatigue tested under conditions where active water flow of either 1.7 m/sec. or 4.7 m/sec. was applied parallel to the crack. Earlier experiments on unclad surface-cracked specimens of the same steel exhibited EAC under quasi- stagnant conditions, but water flow rates at 1.7 m/sec. and 5.0 m/sec. parallel to the crack mitigated EAC. In the present experiments on clad specimens, water flow at approximately the same as the lower of these velocities did not mitigate EAC, and a free stream velocity approximately the same as the higher of these velocities resulted in sluggish mitigation of EAC. The lack of robust EAC mitigation was attributed to the greater crack surface roughness in the cladding interfering with flow induced within the crack cavity. An analysis employing the computational fluid dynamics code, FIDAP, confirmed that frictional forces associated with the cladding crack surface roughness reduced the interaction between the free stream and the crack cavity.

James, L.A; Lee, H.B.; Wire, G.L.; Novak, S.R. [Bettis Atomic Power Lab., West Mifflin, PA (United States); Cullen, W.H. [Materials Engineering Associates, Inc., Lanham, MD (United States)

1996-04-01T23:59:59.000Z

157

Accelerated Fatigue Crack Growth Behavior of PWA 1480 Single ...  

Science Conference Proceedings (OSTI)

3 456. 610. 1520 30. AK . AKrss. MPa v'?! Fig. 10 Fatigue crack growth rate as a function of AKrss and AK. Prediction of the Microscopic Crack Behavior: An ...

158

Reading of cracked optical discs using iterative learning control  

Science Conference Proceedings (OSTI)

Optical discs, including Compact Discs (CDs), Digital Versatile Discs (DVDs), and Blu-ray Discs (BDs), can get cracked during storage and usage. Such cracks commonly lead to discontinuities in the data track, potentially preventing reading of the data ...

Maarten Steinbuch; Koos Van Berkel; George Leenknegt; Tom Oomen; Jeroen Van De Wijdeven

2009-06-01T23:59:59.000Z

159

Stress Corrosion Cracking of Steel In Concentrated Nitrate ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2011. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title, Stress ...

160

Interaction between Local Strains and Stress Corrosion Cracks ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Environmentally Assisted Cracking (EAC): Laboratory Research and Field ...

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Stress Corrosion Cracking Observation in API G-105 Grade Drill ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2011. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title, Stress ...

162

Environmentally Assisted Cracking of Stainless Steels and Nickel ...  

Science Conference Proceedings (OSTI)

Oct 10, 2012 ... Intergranular Stress Corrosion Cracking (IGSCC) Mechanism of Structural Component Materials in Pressurized Water Reactors : Young Suk ...

163

stress corrosion cracking of iron and nickel based alloys  

Science Conference Proceedings (OSTI)

This Table of Contents is from Chemistry and Electrochemistry of Corrosion and Stress Corrosion Cracking published by TMS.

164

U.S. Refinery Thermal Cracking, Visbreaking Downstream Charge ...  

U.S. Energy Information Administration (EIA)

U.S. Refinery Thermal Cracking, Visbreaking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

165

Guam Refinery Thermal Cracking/Visbreaking Downstream Charge ...  

U.S. Energy Information Administration (EIA)

Guam Refinery Thermal Cracking/Visbreaking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

166

Guam Refinery Thermal Cracking/Other (including Gas Oil ...  

U.S. Energy Information Administration (EIA)

Guam Refinery Thermal Cracking/Other (including Gas Oil) Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

167

U.S. Refinery Thermal Cracking, Fluid Coking Downstream Charge ...  

U.S. Energy Information Administration (EIA)

U.S. Refinery Thermal Cracking, Fluid Coking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

168

Girth Weld Cracking at Ethanol Terminal Facilities - Programmaster ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Failure Analysis and Prevention. Presentation Title, Girth Weld Cracking at ...

169

Puerto Rico Refinery Thermal Cracking/Visbreaking Downstream ...  

U.S. Energy Information Administration (EIA)

Puerto Rico Refinery Thermal Cracking/Visbreaking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

170

Latent Cracking of Tantalum - Titanium Welds Due to Hydrogen ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2012. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title, Latent ...

171

Molecular Dynamics of Fatigue Crack Growth in Nanocrystalline ...  

Science Conference Proceedings (OSTI)

Experimental techniques are prohibitive due to limitations of nano samples and advanced microscopic manipulators. In this study, crack propagation under ...

172

Honeywords: making password-cracking detectable  

Science Conference Proceedings (OSTI)

We propose a simple method for improving the security of hashed passwords: the maintenance of additional ``honeywords'' (false passwords) associated with each user's account. An adversary who steals a file of hashed passwords and inverts the hash function ... Keywords: authentication, chaffing, honeywords, login, password cracking, password hashes, passwords

Ari Juels, Ronald L. Rivest

2013-11-01T23:59:59.000Z

173

Fuzzy modeling of fluidized catalytic cracking unit  

Science Conference Proceedings (OSTI)

The paper deals with the fuzzy system identification of reactor-regenerator-stripper-fractionator's (RRSF) section of a fluidized catalytic cracking unit (FCCU). The fuzzy system identification based on the data collected from an operating refinery of ... Keywords: Dynamic fuzzy model, FCCU models, Fuzzy clustering, Fuzzy inference systems, Fuzzy models, Hybrid learning, Mountain clustering, Supervised learning, Unsupervised learning

Mohammad Fazle Azeem; Nesar Ahmad; M. Hanmandlu

2007-01-01T23:59:59.000Z

174

Cracked rotor vibrations by multifractal analysis  

E-Print Network (OSTI)

Multifractal analysis has been used to diagnoze cracked and healthy rotors. Is has been shown that the complexity and regularity criteria of the dynamical systems defined by the multiple scaling of the time series can indicate the damages of the rotating shaft.

Grzegorz Litak; Jerzy T. Sawicki

2008-04-15T23:59:59.000Z

175

Strip edge cracking simulation in cold rolling  

SciTech Connect

This research work focuses on a specific defect which occurs during cold rolling of steel strips: edge-serration. Investigations on the industrial processes have led to the conclusion that this defect is the result of the edge-trimming and cold rolling sequences. The aim of this research work is to analyze the effect of the cutting process and the cold rolling on cracks occurrence, especially on strip edges.This study is performed using an experimental testing stand called Upsetting Rolling Test (URT). It allows to reproduce cold rolling contact parameters such as forward slip, reduction ratio and friction coefficients. Specimens sampled near trimmed industrial strip edges are deformed using the URT stand. Two sets of specimens with different stress states, obtained by annealing, are submitted to two reduction passes with extreme forward slips.Scanning electron microscopy observations added to 3D optical surface profiler topographies show that on one hand, forward slip has a major effect on cracks opening. On the other hand, cracks opening decreases according to high roll strip speed gradient. Concerning the heat-treated specimens, no crack appeared after all reduction passes, showing a large influence of the cutting process and consequently of the local stress state in the vicinity of the burnish and fracture regions.

Hubert, C.; Dubar, L.; Dubar, M.; Dubois, A. [Univ Lille Nord de France, F-59000 Lille (France); UVHC, TEMPO EA 4542, F-59313 Valenciennes (France)

2011-01-17T23:59:59.000Z

176

Segmentation of cracks in shale rock  

Science Conference Proceedings (OSTI)

In this paper the use of morphological connected filters are studied for segmenting sheet- and thread-like cracks in images of shale rock. A volume formed from a stack of 2-D X-ray images is processed using 3-D attributes. The shape-preserving property ...

Erik R. Urbach; Marina Pervukhina; Leanne Bischof

2011-07-01T23:59:59.000Z

177

Digital radiographic systems detect boiler tube cracks  

SciTech Connect

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.

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

2008-06-15T23:59:59.000Z

178

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

E-Print Network (OSTI)

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 ...

Gibbs, Jonathan Paul

2011-01-01T23:59:59.000Z

179

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

E-Print Network (OSTI)

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 ...

Gibbs, Jonathan Paul

180

Isotope Effects and Helium Retention Behavior in Vanadium Tritide  

SciTech Connect

The relaxation times of the H, T, and 3He nuclei have been measured in vanadium hydride and tritide samples. Substantial isotope effects in both the phase transition temperatures and diffusion parameters have been found. When compared to hydrides, the tritide samples have lower transition temperatures and faster mobilities. The differences in the occupancies of the interstitial sites are largely responsible for these isotope effects. Most of the helium atoms generated by tritium decay remain trapped in microscopic bubbles formed with the VTx lattice. Evidence is presented for the gradual growth of the helium bubbles over periods of hundreds of days.

Bowman, Jr., R. C.; Attalla, A., and Craft, B. D.

1985-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Development of simplified crack arrest measurements and application procedures for gas storage tanks and pipelines. Final report, November 1986-February 1992  

SciTech Connect

There has been concern with regard to the presence of weld-induced fabrication flaws in 9 percent nickel steel LNG storage tanks. Previous studies have shown that structural integrity can be assured if the material has the ability to arrest a running crack with an adequate margin of safety. Current experiment used to demonstrate crack arrest capability requires large specimens and thus is not acceptable for routine industry applications. A simplified test and analysis method to determine crack arrest toughness is of great value to the gas industry.

Kanninen, M.F.; Dexter, R.J.; Tweedy, L.K.

1992-02-01T23:59:59.000Z

182

PICEP: Pipe Crack Evaluation Program (Revision 1): Special report  

Science Conference Proceedings (OSTI)

This report describes software for calculating single- or two-phase flow through cracks in pipes and steam generator tubes. Options are available for calculating the crack-opening area and the critical (stable) crack length. The program is useful in performing leak-before-break analysis to demonstrate detectable leak rates prior to crack growth instability. Input to the code includes material properties, loads, thermal-hydraulic conditions, pipe geometry, and crack type and orientation. Theory and user information are provided in this report. 16 refs., 7 figs.

Norris, D.M.; Chexal, B.

1987-12-01T23:59:59.000Z

183

A liquid helium cryogenic system design for the GEM magnet  

SciTech Connect

The Superconducting Super Collider (SSC) Gammas, Electrons, Muons (GEM) magnet is a large superconducting solenoid with a total mass of 1.05 {times} 10{sup 6} kg and a stored energy of 2.5 G. A cryogenic system to cool and to maintain the GEM magnet to liquid helium temperature is described. The system is designed to operate effectively under a variety of operating conditions, including cooldown/warm-up, steady state operations, and quench. Primary cooling during steady-state operation is based on natural circulation thermosiphon flow through cooling tubes in the solenoid support bobbin. Additional cooling loops are included for lead and joint cooling and conductor stabilization. A helium refrigerator/liquefier rated at 2 kill and 20 g/s will be specified to meet the refrigeration requirements. Cooldown of the magnet from 300 K to liquid nitrogen temperatures is accomplished using a counterflow helium-to-liquid-nitrogen heat exchanger independent of the helium refrigerator. The system incorporates provisions for maintenance access during accelerator beam operation.

Deis, G.; Warren, R.P. [Lawrence Livermore National Lab., CA (United States); Richied, D.E.; Martovetsky, N.N.; Krupczak, J.J.; Sidi-Yekhlef, A.; Pace, J.R.; Collins, C.A. [Superconducting Super Collider Lab., Dallas, TX (United States)

1993-06-01T23:59:59.000Z

184

The Liquefaction of Hydrogen and Helium Using Small Coolers  

DOE Green Energy (OSTI)

This report discusses the history of the liquefaction of hydrogen and helium using small coolers. This history dates form the 1960's when two stage GM coolers capable of reaching 7 K were used to liquefy helium and hydrogen by suing an added compressor and J-T circuit. Liquefaction using the added circuit failed to become mainstream because the J-T valve and heat exchanger clogged because of impurities in the gas being liquefied. Liquefaction using a GM cooler without an added J-T circuit proved to be difficult because the first stage was not used to pre-cool the gas coming to the second stage of the cooler. Once the gas being liquefied was pre-cooled using the cooler first stage, improvements in the liquefaction rates were noted. The advent of low temperature pulse tube cooler (down to 2.5 K) permitted one to achieve dramatic improvement is the liquefactions rates for helium. Similar but less dramatic improvements are expected for hydrogen as well. Using the PT-415 cooler, one can expect liquefaction rates of 15 to 20 liters per day for helium or hydrogen provided the heat leak into the cooler and the storage vessel is low. A hydrogen liquefier for MICE is presented at the end of this report.

Green, Michael A.

2006-02-12T23:59:59.000Z

185

Etching of Graphene Devices with a Helium Ion Beam  

E-Print Network (OSTI)

IM microscope image in Figure 2a, was He ion etched by sequen- tial imaging in high resolution. The grapheneEtching of Graphene Devices with a Helium Ion Beam Max C. Lemme, David C. Bell,,§ James R. Williams as for pos- sible nanoelectronics applications.1 3 Many experiments in the field are targeted at graphene

Lukin, Mikhail

186

Charge Distribution about an Ionizing Electron Track in Liquid Helium  

E-Print Network (OSTI)

The dependence on an applied electric field of the ionization current produced by an energetic electron stopped in liquid helium can be used to determine the spatial distribution of secondary electrons with respect to their geminate partners. An analytic expression relating the current and distribution is derived. The distribution is found to be non-Gaussian with a long tail at larger distances.

G. M. Seidel; T. M. Ito; A. Ghosh; B. Sethumadhavan

2013-10-04T23:59:59.000Z

187

TRANSMISSION ELECTRON MICROSCOPY STUDY OF HELIUM BEARING FUSION WELDS  

DOE Green Energy (OSTI)

A transmission electron microscopy (TEM) study was conducted to characterize the helium bubble distributions in tritium-charged-and-aged 304L and 21Cr-6Ni-9Mn stainless steel fusion welds containing approximately 150 appm helium-3. TEM foils were prepared from C-shaped fracture toughness test specimens containing {delta} ferrite levels ranging from 4 to 33 volume percent. The weld microstructures in the low ferrite welds consisted mostly of austenite and discontinuous, skeletal {delta} ferrite. In welds with higher levels of {delta} ferrite, the ferrite was more continuous and, in some areas of the 33 volume percent sample, was the matrix/majority phase. The helium bubble microstructures observed were similar in all samples. Bubbles were found in the austenite but not in the {delta} ferrite. In the austenite, bubbles had nucleated homogeneously in the grain interiors and heterogeneously on dislocations. Bubbles were not found on any austenite/austenite grain boundaries or at the austenite/{delta} ferrite interphase interfaces. Bubbles were not observed in the {delta} ferrite because of the combined effects of the low solubility and rapid diffusion of tritium through the {delta} ferrite which limited the amount of helium present to form visible bubbles.

Tosten, M; Michael Morgan, M

2008-12-12T23:59:59.000Z

188

PULSATIONS IN HYDROGEN BURNING LOW-MASS HELIUM WHITE DWARFS  

SciTech Connect

Helium core white dwarfs (WDs) with mass M {approx}< 0.20 M {sub sun} undergo several Gyr of stable hydrogen burning as they evolve. We show that in a certain range of WD and hydrogen envelope masses, these WDs may exhibit g-mode pulsations similar to their passively cooling, more massive carbon/oxygen core counterparts, the ZZ Cetis. Our models with stably burning hydrogen envelopes on helium cores yield g-mode periods and period spacings longer than the canonical ZZ Cetis by nearly a factor of 2. We show that core composition and structure can be probed using seismology since the g-mode eigenfunctions predominantly reside in the helium core. Though we have not carried out a fully nonadiabatic stability analysis, the scaling of the thermal time in the convective zone with surface gravity highlights several low-mass helium WDs that should be observed in search of pulsations: NLTT 11748, SDSS J0822+2753, and the companion to PSR J1012+5307. Seismological studies of these He core WDs may prove especially fruitful, as their luminosity is related (via stable hydrogen burning) to the hydrogen envelope mass, which eliminates one model parameter.

Steinfadt, Justin D. R. [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106 (United States); Bildsten, Lars [Kavli Institute for Theoretical Physics and Department of Physics, Kohn Hall, University of California, Santa Barbara, CA 93106 (United States); Arras, Phil, E-mail: jdrs@physics.ucsb.ed, E-mail: bildsten@kitp.ucsb.ed, E-mail: arras@virginia.ed [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States)

2010-07-20T23:59:59.000Z

189

Process for magnetic beneficiating petroleum cracking catalyst  

DOE Patents (OSTI)

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.

Doctor, Richard D. (Lisle, IL)

1993-01-01T23:59:59.000Z

190

Circumferential cracking of steam generator tubes  

SciTech Connect

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.

Karwoski, K.J.

1997-04-01T23:59:59.000Z

191

Process for magnetic beneficiating petroleum cracking catalyst  

DOE Patents (OSTI)

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.

Doctor, R.D.

1993-10-05T23:59:59.000Z

192

Structures for dense, crack free thin films  

DOE Patents (OSTI)

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.

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

2011-03-08T23:59:59.000Z

193

Methane cracking over a bituminous coal char  

Science Conference Proceedings (OSTI)

Methane cracking over a bed of Chinese bituminous coal char was studied using a fixed-bed reactor at atmospheric pressure and temperatures between 1073 and 1223 K. Methane conversion over the fresh char increased with increasing temperature to 90% at 1223 K. Hydrogen was the only gas-phase product that was detected during the experimentation. The char was shown to exert a significant catalytic effect on methane cracking by comparing results from experiments with the raw char and demineralised char as well as from blank experiments using quartz. It was further shown that the ash was not the source of the catalytic effect of the char. However, both methane conversion and hydrogen yield decreased with increasing reaction time, irrespective of other experimental conditions, indicating that the char rapidly became deactivated following the exposure to methane. It was speculated that the deposition of carbon from methane cracking was responsible for this deactivation, which is supported by scanning electron microscopy (SEM) image analysis. It was demonstrated that the catalytic activity of the deactivated char can be partially recovered by burning off the carbon deposits with an oxidizing gas mixture containing 0.46% oxygen. 10 refs., 11 figs., 1 tab.

Zhi-qiang Sun; Jin-hu Wu; Mohammad Haghighi; John Bromly; Esther Ng; Hui Ling Wee; Yang Wang; Dong-ke Zhang [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

2007-06-15T23:59:59.000Z

194

Impurity gettering in silicon using cavities formed by helium implantation and annealing  

DOE Patents (OSTI)

Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer.

Myers, Jr., Samuel M. (Albuquerque, NM); Bishop, Dawn M. (Albuquerque, NM); Follstaedt, David M. (Albuquerque, NM)

1998-01-01T23:59:59.000Z

195

Impurity gettering in silicon using cavities formed by helium implantation and annealing  

DOE Patents (OSTI)

Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer. 4 figs.

Myers, S.M. Jr.; Bishop, D.M.; Follstaedt, D.M.

1998-11-24T23:59:59.000Z

196

Visualization Study of Counterflow in Superfluid {sup 4}He using Metastable Helium Molecules  

SciTech Connect

Heat is transferred in superfluid {sup 4}He via a process known as thermal counterflow. It has been known for many years that above a critical heat current the superfluid component in this counterflow becomes turbulent. It has been suspected that the normal-fluid component may become turbulent as well, but experimental verification is difficult without a technique for visualizing the flow. Here we report a series of visualization studies on the normal-fluid component in a thermal counterflow performed by imaging the motion of seeded metastable helium molecules using a laser-induced-fluorescence technique. We present evidence that the flow of the normal fluid is indeed turbulent at relatively large velocities. Thermal counterflow in which both components are turbulent presents us with a theoretically challenging type of turbulent behavior that is new to physics.

Guo, W.; Cahn, S. B.; Nikkel, J. A.; McKinsey, D. N. [Physics Department, Yale University, New Haven, Connecticut 06515 (United States); Vinen, W. F. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

2010-07-23T23:59:59.000Z

197

Cold Vacuum Drying (CVD) Facility General Service Helium System Design Description  

DOE Green Energy (OSTI)

The purpose of this System Design Description (SDD) is to describe the characteristics of the Cold Vacuum Drying (CVD) Facility general service helium system. The general service helium system is a general service facility process support system, but does include safety-class structures, systems and components (SSCs) providing protection to the offsite public. The general service helium system also performs safety-significant functions that provide protection to onsite workers. The general helium system essential function is to provide helium (He) to support process functions during all phases of facility operations. General service helium is used to purge the cask and the MCO in order to maintain their internal atmospheres below hydrogen flammability concentrations. The general service helium system also supplies helium to purge the process water conditioning (PWC) lines and components and the vacuum purge system (VPS) vacuum pump. The general service helium system, if available following an Safety Class Instrument and Control System (SCIC) Isolation and Purge (IS0 and PURGE) Trip, can provide an alternate general service helium system source to supply the Safety-Class Helium (SCHe) System.

SHAPLEY, B.J.

2000-04-20T23:59:59.000Z

198

Crack tip plasticity in single crystal UO2: Atomistic simulations  

SciTech Connect

The fracture behavior of single crystal uranium dioxide is studied using molecular dynamics simulations at room temperature. Initially, an elliptical notch is created on either {111} or {110} planes, and tensile loading is applied normal to the crack planes. For cracks on both planes, shielding of crack tips by plastic deformation is observed, and crack extension occurs for crack on {111} planes only. Two plastic processes, dislocation emission and phase transformation are identified at crack tips. The dislocations have a Burgers vector of ?110?/2, and glide on {100} planes. Two metastable phases, the so-called Rutile and Scrutinyite phases, are identified during the phase transformation, and their relative stability is confirmed by separate density- functional-theory calculations. Examination of stress concentration near crack tips reveals that dislocation emission is not an effective shielding mechanism. The formation of new phases may effectively shield the crack provided all phase interfaces formed near the crack tips are coherent, as in the case of cracks residing on {110} planes.

Yongfeng Zhang; Paul C. Millett; Michael Tonks; Bulent Biner; Xiang-Yang Liu; David A. Andersson

2012-11-01T23:59:59.000Z

199

Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material  

Science Conference Proceedings (OSTI)

Stress corrosion cracking is one of the most common corrosion-related causes for premature breach of metal structural components. Stress corrosion cracking is the initiation and propagation of cracks in structural components due to three factors that must be present simultaneously: metallurgical susceptibility, critical environment, and static (or sustained) tensile stresses. This report was prepared according to ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The purpose of this report is to provide an evaluation of the potential for stress corrosion cracking of the engineered barrier system components (i.e., the drip shield, waste package outer barrier, and waste package stainless steel inner structural cylinder) under exposure conditions consistent with the repository during the regulatory period of 10,000 years after permanent closure. For the drip shield and waste package outer barrier, the critical environment is conservatively taken as any aqueous environment contacting the metal surfaces. Appendix B of this report describes the development of the SCC-relevant seismic crack density model (SCDM). The consequence of a stress corrosion cracking breach of the drip shield, the waste package outer barrier, or the stainless steel inner structural cylinder material is the initiation and propagation of tight, sometimes branching, cracks that might be induced by the combination of an aggressive environment and various tensile stresses that can develop in the drip shields or the waste packages. The Stainless Steel Type 316 inner structural cylinder of the waste package is excluded from the stress corrosion cracking evaluation because the Total System Performance Assessment for License Application (TSPA-LA) does not take credit for the inner cylinder. This document provides a detailed description of the process-level models that can be applied to assess the performance of Alloy 22 (used for the waste package outer barrier) and Titanium Grade 7 (used for the drip shield) that are subjected to the effects of stress corrosion cracking. The use of laser peening or other residual stress mitigation techniques is considered as a means of mitigating stress corrosion cracking in the waste package final closure lid weld.

G. Gordon

2004-10-13T23:59:59.000Z

200

Role of crack tip shielding in the initiation and growth of long and small fatigue cracks in composite microstructures  

Science Conference Proceedings (OSTI)

The role of crack tip shielding in retarding the initiation and growth of fatigue cracks has been examined in metallic composite microstructures (consisting of hard and soft phases), with the objective of achieving maximum resistance to fatigue. Specifically, duplex ferritic-martensitic structures have been developed in AISI 1008 and 1015 mild steels to promote shielding without loss in strength. The shielding is developed primarily from crack deflection and resultant crack closure, such that unusually high long crack propagation resistance is obtained. It is found that the fatigue threshold ..delta..K/sub TH/ in AISI 1008 can be increased by more than 100 pct to over 20 MPa ..sqrt..m, without sacrifice in strength, representing the highest ambient temperature threshold reported for a metallic alloy to date. Similar but smaller increases are found in AISI 1015. The effect of the dual-phase microstructures on crack initiation and small crack (10 to 1000 ..mu..m) growth, however, is markedly different, characteristic of behavior influenced by the mutual competition of intrinsic and extrinsic (shielding) ''toughening'' mechanisms. Accordingly, the composite microstructures which appear to show the highest resistance to the growth of long cracks, show the lowest resistance to crack initiation and small crack growth. In general, dual-phase steels are found to display remarkable fatigue properties, with fatigue limits as high as 58 pct of the tensile strengths and fatigue thresholds in the range of 13 to 20 MPa..sqrt..m.

Shang, J.K.; Tzou, J.L.; Ritchie, R.O. (Materials and Chemical Sciences Div., Lawrence Berkeley Lab., and Dept. of Materials Science and Mineral Engineering, Univ. of California, Berkeley, CA (US))

1987-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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201

Pulsed extraction of ionization from helium buffer gas  

E-Print Network (OSTI)

The migration of intense ionization created in helium buffer gas under the influence of applied electric fields is considered. First the chemical evolution of the ionization created by fast heavy-ion beams is described. Straight forward estimates of the lifetimes for charge exchange indicate a clear suppression of charge exchange during ion migration in low pressure helium. Then self-consistent calculations of the migration of the ions in the electric field of a gas-filled cell at the National Superconducting Cyclotron Laboratory (NSCL) using a Particle-In-Cell computer code are presented. The results of the calculations are compared to measurements of the extracted ion current caused by beam pulses injected into the NSCL gas cell.

D. J. Morrissey; G. Bollen; M. Facina; S. Schwarz

2008-08-13T23:59:59.000Z

202

Satellite spectra for helium-like titanium. Part II  

Science Conference Proceedings (OSTI)

K/sup ..cap alpha../ x-ray spectra of helium-like titanium, Ti XXI, from Tokamak Fusion Test Reactor (TFTR) plasmas have been observed with a high resolution crystal spectrometer and have been used as a diagnostic of central plasma parameters. The data allow detailed comparison with recent theoretical predictions for the Ti XXI helium-like lines and the associated satellite spectrum in the wavelength range from 2.6000 to 2.6400 A. Improved values for the excitation rate coefficients of the Ti XXI resonance line, the intercombination lines and the forbidden line, and new theoretical results on the wavelengths and transition probabilities for beryllium-like satellites due to transitions of the type 1s/sup 2/ 2lnl' - 1s2p2l'' nl'' with n = 2-4 have been calculated.

Bitter, M.; Hill, K.W.; Zarnstorff, M.; von Goeler, S.; Hulse, R.; Johnson, L.C.; Sauthoff, N.R.; Sesnic, S.; Young, K.M.; Tavernier, M.

1985-08-01T23:59:59.000Z

203

Shock Wave Structure for Argon, Helium, and Nitrogen  

E-Print Network (OSTI)

We compare the thickness of shock wave fronts at different Mach numbers, modeled via Navier-Stokes (NS) and Quasi-gasdynamic (QGD) equations, with experimental results from the literature. Monoatomic argon and helium, and diatomic nitrogen, are considered. In this modeling a finite-difference scheme with second-order spatial accuracy is employed. For argon the density thickness calculated via QGD and NS models are in good agreement with each other, and with the experimental results. For helium QGD and NS results agree well with those from the bimodal model. For nitrogen, the QGD results are closer to the experimental data than NS results. The QGD-based algorithm converges to the steady state solution faster than the NS-based one.

T. G. Elizarova; I. A. Shirokov; S. Montero

2004-07-28T23:59:59.000Z

204

A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor  

E-Print Network (OSTI)

A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

1998-01-01T23:59:59.000Z

205

Stimulated Brillouin Scattering from Helium-Hydrogen Plasmas  

DOE Green Energy (OSTI)

An extensive study of the stimulated Brillouin scattering (SBS) in helium-hydrogen plasmas has been performed using a gas jet at the Janus Laser Facility. We observe three regions of reflectivity by varying the probe intensity from 10{sup 14} to 10{sup 16}: saturated region, linear region, and near SBS threshold region. In the linear regime, adding small amounts of H to a He plasma reduces the SBS reflectivity by a factor of 4.

Froula, D H; Divol, L; Price, D; Gregori, G; Williams, E A; Glenzer, S H

2003-08-22T23:59:59.000Z

206

Open Questions in Stellar Helium Burning Addressed With Real Photons  

E-Print Network (OSTI)

The outcome of helium burning is the formation of the two elements, carbon and oxygen. The ratio of carbon to oxygen at the end of helium burning is crucial for understanding the final fate of a progenitor star and the nucleosynthesis of heavy elements in Type II supernova, with oxygen rich star predicted to collapse to a black hole, and a carbon rich star to a neutron star. Type Ia supernovae (SNeIa) are used as standard candles for measuring cosmological distances with the use of an empirical light curve-luminosity stretching factor. It is essential to understand helium burning that yields the carbon/oxygen white dwarf and thus the initial stage of SNeIa. Since the triple alpha-particle capture reaction, $^{8}Be(\\alpha,\\gamma)^{12}C$, the first burning stage in helium burning, is well understood, one must extract the cross section of the $^{12}C(\\alpha,\\gamma)^{16}O$ reaction at the Gamow window (300 keV) with high accuracy of approximately 10% or better. This goal has not been achieved despite repeated strong statements that appeared in the literature. In particular constraint from the beta-delayed alpha-particle emission of $^{16}N$ were shown to not sufficiently restrict the p-wave cross section factor; e.g. a low value of $S_{E1}(300)$ can not be ruled out. Measurements at low energies, are thus mandatory for determining the elusive cross section factor for the $^{12}C(\\alpha,\\gamma)^{16}O$ reaction. We are constructing a Time Projection Chamber (TPC) for use with high intensity photon beams extracted from the HI$\\gamma$S/TUNL facility at Duke University to study the $^{16}O(\\gamma,\\alpha)^{12}C$ reaction, and thus the direct reaction at energies as low as 0.7 MeV. This work is in progress.

Moshe Gai

2003-03-20T23:59:59.000Z

207

Semiclassical description of antiproton capture on atomic helium  

SciTech Connect

A semiclassical, many-body atomic model incorporating a momentum-dependent Heisenberg core to stabilize atomic electrons is used to study antiproton capture on helium. Details of the antiproton collisions leading to eventual capture are presented, including the energy and angular-momentum states of incident antiprotons which result in capture via single- or double-electron ionization, i.e., into He[sup 2+][ital [bar p

Beck, W.A. (Department of Physics, University of Washington, Seattle, Washington 98195 (United States) Quantum Medical Systems, Issaquah, Washington 98027 (United States)); Wilets, L. (Department of Physics, University of Washington, Seattle, Washington 98195 (United States)); Alberg, M.A. (Department of Physics, University of Washington, Seattle, Washington 98195 (United States) Department of Physics, Seattle University, Seattle, Washington 98122 (United States))

1993-10-01T23:59:59.000Z

208

Mathematical modeling of a Fermilab helium liquefier coldbox  

SciTech Connect

Fermilab Central Helium Liquefier (CHL) facility is operated 24 hours-a-day to supply 4.6{degrees}K for the Fermilab Tevatron superconducting proton-antiproton collider Ring and to recover warm return gases. The centerpieces of the CHL are two independent cold boxes rated at 4000 and 5400 liters/hour with LN{sub 2} precool. These coldboxes are Claude cycle and have identical heat exchangers trains, but different turbo-expanders. The Tevatron cryogenics demand for higher helium supply from CHL was the driving force to investigate an installation of an expansion engine in place of the Joule-Thompson valve. A mathematical model was developed to describe the thermo- and gas-dynamic processes for the equipment included in the helium coldbox. The model is based on a finite element approach, opposite to a global variables approach, thus providing for higher accuracy and conversion stability. Though the coefficients used in thermo- and gas-dynamic equations are unique for a given coldbox, the general approach, the equations, the methods of computations, and most of the subroutines written in FORTRAN can be readily applied to different coldboxes. The simulation results are compared against actual operating data to demonstrate applicability of the model.

Geynisman, M.G.; Walker, R.J.

1995-12-01T23:59:59.000Z

209

UCN production by multiphonon processes in superfluid Helium under pressure  

E-Print Network (OSTI)

Cold neutrons are converted to ultra-cold neutrons (UCN) by the excitation of a single phonon or multiphonons in superfluid helium. The dynamic scattering function S(q, omega) of the superfluid helium strongly depends on pressure, leading to a pressure- dependent differential UCN production rate. A phenomenological expression for the multiphonon part of the scattering function s(lambda) describing UCN production has been derived from inelastic neutron scattering data. When combined with the production rate from single phonon processes this allows us to calculate the UCN production for any incident neutron flux. For calculations of the UCN production from single phonon processes we propose to use the values for S*(SVP) = 0.118(8) and S*(20 bar) = 0.066(6). As an example we will calculate the expected UCN production rate at the cold neutron beam for fundamental physics PF1b at the Institut Laue Langevin. We conclude that UCN production in superfluid helium under pressure is not attractive.

P. Schmidt-Wellenburg; K. H. Andersen; O. Zimmer

2008-11-26T23:59:59.000Z

210

On the Evolution of Helium in Blue Compact Galaxies  

E-Print Network (OSTI)

We discuss the chemical evolution of dwarf irregular and blue compact galaxies in light of recent data, new stellar yields and chemical evolution models. We examine the abundance data for evidence of HII region self-enrichment effects, which would lead to correlations in the scatter of helium, nitrogen, and oxygen abundances around their mean trends. The observed helium abundance trends show no such correlations, though the nitrogen--oxygen trend does show strong evidence for real scatter beyond observational error. We construct simple models for the chemical evolution of these galaxies, using the most recent yields of \\he4, C, N and O in intermediate- and high-mass stars. The effects of galactic outflows, which can arise both from bulk heating and evaporation of the ISM, and from the partial escape of enriched supernova ejecta are included. In agreement with other studies, we find that supernova-enriched outflows can roughly reproduce the observed He, C, N, and O trends; however, in models that fit N versus O, the slopes $\\Delta Y/\\Delta$O and $\\Delta Y/\\Delta$N consistently fall more than $2\\sigma$ below the fit to observations. We discuss the role of the models and their uncertainties in the extrapolation of primordial helium from the data. We also explore the model dependence arising nucleosynthesis uncertainties associated with nitrogen yields in intermediate mass stars, the fate of $8-11 \\msol$ stars, and massive star winds.

Brian D. Fields; Keith A. Olive

1998-03-25T23:59:59.000Z

211

Relationships Between Stress Corrosion Cracking Tests and Utility ...  

Science Conference Proceedings (OSTI)

Aug 1, 1999 ... Several utility steam generator and stress corrosion cracking ... Superheated steam and neutral solution environments are found to be ...

212

Influence of Different Cooling Structure on Surface Crack of HSLA ...  

Science Conference Proceedings (OSTI)

Presentation Title, Influence of Different Cooling Structure on Surface Crack of .... of Si3N4-SiC Heat Absorption Ceramic Material Used for Tower Type Solar ...

213

Basic Aspects of Superalloy Design for Crack Growth Resistance  

Science Conference Proceedings (OSTI)

theories for fatigue and creep crack growth resistance that are particularly ... devices as the nuclear reactors and in such strategic and expensive vehicles.

214

Fatigue Property-Microstructure Relationships and Crack Growth  

Science Conference Proceedings (OSTI)

Feb 28, 2011 ... Effect of Microstructure on Fatigue Behavior of Two Pipeline Steels: .... to a transition crack length (LEFM applicable) is approximated using ...

215

In-vitro Evaluation of Stress Corrosion Cracking of Biomedical ...  

Science Conference Proceedings (OSTI)

In this study, the susceptibility to stress corrosion cracking of biodegradable and aluminium-free magnesium alloys, WZ21 and WE43, was investigated using ...

216

Corrosion Inhibition of Stress Corrosion Cracking and Localized ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Stress corrosion cracking of 7050 aluminum alloys in the turbo expander industry can cause expensive catastrophic failures, especially for turbo

217

Strain Rate Sensitivity of Alloy 718 Stress Corrosion Cracking  

Science Conference Proceedings (OSTI)

Stress corrosion cracking (SCC) tests were conducted in 36O'C pressurized- water-reactor. (PWR) primary water using. Alloy 718 heat-treated to produce.

218

Stress Corrosion Cracking of Aluminium-Free Magnesium Alloys in ...  

Science Conference Proceedings (OSTI)

Presentation Title, Stress Corrosion Cracking of Aluminium-Free Magnesium Alloys in a Simulated Human Body Fluid. Author(s), Lokesh Choudhary, R. K. Singh ...

219

Environmentally Assisted Cracking of Alloy 7050-T7451 Exposed to ...  

Science Conference Proceedings (OSTI)

Under cyclic loading notched specimens failed by transgranular stress corrosion cracking. Striations were observed on the cleavage-like facets. The number of ...

220

Stress Corrosion Crack Initiation of Alloy 690 in Subcritical and ...  

Science Conference Proceedings (OSTI)

Abstract Scope, The objective of this study is to investigate the structure and chemistry of corrosion and stress corrosion crack initiation in Alloy 690. To avoid

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

grain boundary oxidation and stress corrosion cracking in nickel ...  

Science Conference Proceedings (OSTI)

Accelerated stress corrosion cracking tests and exposures were conducted on alloy 600, Ni-9Fe, and Ni-9Fe-5Cr (LCr) in constant extension rate mode in ...

222

Model for the Superimposed Effects of Stress-Corrosion Cracking ...  

Science Conference Proceedings (OSTI)

Symposium, Fatigue and Corrosion Damage in Metallic Materials: Fundamentals, ... and a stress-corrosion cracking mode acting at high stress intensity in NaCl.

223

Stress Corrosion Cracking Threshold of Ti 6-4 Extrusions  

Science Conference Proceedings (OSTI)

Ti 6Al-4V extrusions with standard chemistry and extra low interstitial are evaluated for their stress corrosion cracking resistance. Also examined is the affect of ...

224

A Study on the Stress Corrosion Cracking Mechanism of Carbon ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Carbon steel is susceptible to stress corrosion cracking (SCC) in fuel grade ethanol (FGE). The research results obtained thus far have found ...

225

Stress Corrosion Cracking Initiation of Austenitic Alloys in ...  

Science Conference Proceedings (OSTI)

Presentation Title, Stress Corrosion Cracking Initiation of Austenitic Alloys in Supercritical Water. Author(s), Guoping Cao, Vahid Firouzdor, Todd Allen. On-

226

Galvanic Corrosion and Stress Corrosion Cracking of Steel and ...  

Science Conference Proceedings (OSTI)

No aluminum bolt AW 7075 failed in magnesium due to stress corrosion cracking (SCC). Even aluminum bolts in T6 condition can be used for automotive ...

227

Orientation Effects and Influence of Delta Phase on Fatigue Crack ...  

Science Conference Proceedings (OSTI)

including a hold time at maximum load lead to increased crack propagation rates when compared ... 720°C ;' 8 hours .! controlled cooling rate at 50°C per hour.

228

U.S. Refinery Thermal Cracking, Other (including Gas Oil ...  

U.S. Energy Information Administration (EIA)

U.S. Refinery Thermal Cracking, Other (including Gas Oil) Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

229

Stress Corrosion Cracking of Stabilized Austenitic Stainless Steels ...  

Science Conference Proceedings (OSTI)

Aug 1, 1999 ... Stress Corrosion Cracking of Stabilized Austenitic Stainless Steels in Various Types of Nuclear Power Plants by M.O. Speidel and R.

230

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

Open Energy Info (EERE)

P wave anisotropy, stress, and crack distribution at Coso geothermal field, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: P wave...

231

Failure Analysis of a Cracked Thermite Welded Rail Section  

Science Conference Proceedings (OSTI)

Brittle fracture followed the fatigue crack propagation causing complete separation of the rail. Although the excess material was thought to reinforce the rails it ...

232

Thermal Cracking of Large-Diameter 706 Ingots  

Science Conference Proceedings (OSTI)

responsible for the cracking. The most plausible scenario is that residual stresses generated by ... Analysis of Heat Up for Homogenization. Finite Element Model.

233

High-Temperature Stress Relaxation Cracking and Stress Rupture ...  

Science Conference Proceedings (OSTI)

An incident occurred that resulted in the cracking of gasifier internals, bulging and stress rupture of the shell and the escape of hot syngas, causing a fire.

234

Corrosion Fatigue and Crack Propagation of Different Austenitic ...  

Science Conference Proceedings (OSTI)

A FIB Study of the Resistance of Grain Boundaries to Short Fatigue Crack Propagation in Three-Dimensions in High Strength Al Alloys · A Non-Linear Damage ...

235

Effect of Interstitial Content on High Temperature Fatigue Crack ...  

Science Conference Proceedings (OSTI)

instance; resulted in fatigue crack propagation (FCP)' programs like ESDADTA(2) and ENSIP(3). Fatigue resistance of nickel base superalloys is affected by ...

236

Fatigue and Fatigue Crack Propagation Behaviors of High ...  

Science Conference Proceedings (OSTI)

The S-N fatigue and fatigue crack propagation (FCP) behaviors of high ... The mechanisms associated with the improved fatigue resistance for the high ...

237

Effect of Thermal-Mechanical Treatment on the Fatigue Crack ...  

Science Conference Proceedings (OSTI)

that fatigue crack propagation (FCP) resistance without holding time has no significant difference between three alloys with 718Plus being the best and 718 the ...

238

Intergranular Liquid Formation, Distribution, and Cracking in the ...  

Science Conference Proceedings (OSTI)

zone adjacent to the fusion zone. These intergranular cracks form when liquid ...... 718, and A286 in Light Water Reactor. Environments",. J. Mater. Eng., 2, pp.

239

Stress corrosion cracking of zirconium in nitric acid  

Science Conference Proceedings (OSTI)

The susceptibility of zirconium and its common alloys to stress corrosion cracking (SCC) in nitric acid was investigated by slow strain-rate and constant deflection techniques. Cracking occurred at 25/sup 0/C over a wide range of acid concentrations and electrochemical potentials. The crack velocity increased slightly with increasing temperature. The failure mode was transgranular and the morphology was similar to SCC failures of zirconium alloys in other environments. The fracture was very orientation-dependent suggesting that it occurs on a single crystallographic plane in the material. The results of the study are not consistent with a hydrogen mechanism for cracking.

Beavers, J.A.; Griess, J.C.; Boyd, W.K.

1980-01-01T23:59:59.000Z

240

One-Dimensional Cold Rolling Effects on Stress Corrosion Crack ...  

Science Conference Proceedings (OSTI)

A Microstructural Investigation on the Effect of Cold Work on Environmentally .... Stress Corrosion Cracking Behavior near the Fusion Boundary of Dissimilar ...

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Solidification Cracking Study of High Chromium Nickel-Base Filler ...  

Science Conference Proceedings (OSTI)

... and rank the relative cracking susceptibility of these filler metal specifications. ... Surface Processing of Ag /TiO2 Nanowire Membranes for Solar Photovoltaic ...

242

Research and Evaluation of Low Temperature Crack Propagation of ...  

Science Conference Proceedings (OSTI)

NRC/EPRI Welding Residual Stress Validation Program (Phase III) · On the Microstructure of Alloy 600 SCC Cracks Observed by TEM on PWR SG Pulled Tubes ...

243

DPQ Event Cracked Bushing Leads to Transformer Bank Failure  

Science Conference Proceedings (OSTI)

As part of EPRI's distribution power quality (DPQ) project this power quality (PQ) case study investigates cracked bushing recorded by PQ monitors that led to tranformer bank failure.

2003-12-31T23:59:59.000Z

244

Ranking the Susceptibility to Hydrogen-assisted Cracking in Super ...  

Science Conference Proceedings (OSTI)

Thus, SDSS welds are exposed to hydrogen charging to under CP. There have been reported hydrogen assisted cracking (HAC) failures in SDSS welds during ...

245

Helium-Based Soundwave Chiller: Trillium: A Helium-Based Sonic Chiller- Tons of Freezing with 0 GWP Refrigerants  

SciTech Connect

BEETIT Project: Penn State is designing a freezer that substitutes the use of sound waves and environmentally benign refrigerant for synthetic refrigerants found in conventional freezers. Called a thermoacoustic chiller, the technology is based on the fact that the pressure oscillations in a sound wave result in temperature changes. Areas of higher pressure raise temperatures and areas of low pressure decrease temperatures. By carefully arranging a series of heat exchangers in a sound field, the chiller is able to isolate the hot and cold regions of the sound waves. Penn State’s chiller uses helium gas to replace synthetic refrigerants. Because helium does not burn, explode or combine with other chemicals, it is an environmentally-friendly alternative to other polluting refrigerants. Penn State is working to apply this technology on a large scale.

None

2010-09-01T23:59:59.000Z

246

Short-Crack Response of Alloy 182 Weld Metal Undergoing Stress Corrosion Cracking in High-Temperature PWR Primary Water  

Science Conference Proceedings (OSTI)

Mechanistic investigations of environmentally assisted cracking (EAC), to date, have focused more on propagation relative to initiation. At the same time, components spend most of their life in the initiation and "short-crack" growth regimes. Prior exploratory work conducted at General Electric Global Research Center (GE GRC) showed that stainless steels, Alloy 600, and Alloy 182 weld metal exhibit lower average growth rates when the cracks are very short or small (1050 m). In those tests, the transition...

2008-10-31T23:59:59.000Z

247

Production of carbon monoxide-free hydrogen and helium from a high-purity source  

DOE Patents (OSTI)

The invention provides vacuum swing adsorption processes that produce an essentially carbon monoxide-free hydrogen or helium gas stream from, respectively, a high-purity (e.g., pipeline grade) hydrogen or helium gas stream using one or two adsorber beds. By using physical adsorbents with high heats of nitrogen adsorption, intermediate heats of carbon monoxide adsorption, and low heats of hydrogen and helium adsorption, and by using vacuum purging and high feed stream pressures (e.g., pressures of as high as around 1,000 bar), pipeline grade hydrogen or helium can purified to produce essentially carbon monoxide -free hydrogen and helium, or carbon monoxide, nitrogen, and methane-free hydrogen and helium.

Golden, Timothy Christopher (Allentown, PA); Farris, Thomas Stephen (Bethlehem, PA)

2008-11-18T23:59:59.000Z

248

Helium Recovery in the LHC Cryogenic System following Magnet Resistive Transitions  

E-Print Network (OSTI)

A resistive transition (quench) of the Large Hadron Collider magnets provokes the expulsion of helium from the magnet cryostats to the helium recovery system. A high-volume, vacuum-insulated recovery line connected to several uninsulated medium-pressure gas storage tanks, forms the main constituents of the system. Besides a dedicated hardware configuration, helium recovery also implies specific procedures that should follow a quench, in order to conserve the discharged helium and possibly make use of its refrigeration capability. The amount of energy transferred after a quench from the magnets to the helium leaving the cold mass has been estimated on the basis of experimental data. Based on these data, the helium thermodynamic state in the recovery system is calculated using a lumped parameter approach. The LHC magnet quenches are classified ina parametric way from their cryogenic consequences and procedures that should follow the quench are proposed.

Chorowski, M; Serio, L; Tavian, L; Wagner, U; Van Weelderen, R

1998-01-01T23:59:59.000Z

249

A nanomechanical investigation of the crack tip process zone of marble  

E-Print Network (OSTI)

This study explores the interaction between crack initiation and nanomechanical properties in the crack tip process zone (zone of microcracking at the tip of a propagating crack) of a brittle geomaterial. Samples of Carrara ...

Brooks, Zenzile (Zenzile Z.)

2010-01-01T23:59:59.000Z

250

Evaluation of Circumferential Cracking on Supercritical Boiler Waterwalls  

Science Conference Proceedings (OSTI)

Circumferential cracking of the fireside surfaces of supercritical waterwalls remains a problem for many coal-fired boilers. Two parallel test programs at Pennsylvania Power and Light's (PPL) Brunner Island Unit 3 attempted to correlate operating conditions with the development and propagation of circumferential cracks.

2008-03-31T23:59:59.000Z

251

Micro-crack Damage Evolution of Fracturing Rock Chaotic Characteristics  

Science Conference Proceedings (OSTI)

Chaotic theory and bifurcation of modern nonlinear science were used to study the evolution of micro-cracks under the hydraulic fracturing of the rock mass characteristics, the tensor damage variable which described the chao evolution of micro-cracks ... Keywords: chaos theory, bifurcation theory, damage evolution

Zhaowan Chun; Wang Tingting

2010-06-01T23:59:59.000Z

252

WATER PERMEABILITY OF CRACKED CEMENTITIOUS MICHAEL LEPECH & VICTOR C. LI  

E-Print Network (OSTI)

with inherently tight crack widths, typically less than 80 micron, even when strained up to 5% in uniaxial tension to undergo large deformations while maintaining load capacity. Of interest to this study are the tight crack mixture. Mixing proportions of both materials are shown in Table 1. The sand used in ECC had an average

Lepech, Michael D.

253

Fatigue-crack propagation behavior of Inconel 718  

DOE Green Energy (OSTI)

The techniques of linear-elastic fracture mechanics were used to characterize the effect of several variables (temperature, environment, cyclic frequency, stress ratio, and heat-treatment variations) upon the fatigue-crack growth behavior of Inconel 718 base metal and weldments. Relevant crack growth data on this alloy from other laboratories is also presented. (33 fig, 39 references) (auth)

James, L.A.

1975-09-01T23:59:59.000Z

254

Cold Vacuum Drying (CVD) Facility General Service Helium System Design Description  

DOE Green Energy (OSTI)

This document describes the Cold Vacuum Drying Facility general service helium system (GSHe). The GSHe is a general service facility process support system, but does include safety-class systems, structures and components providing protection to the offsite public. The GSHe also performs safety-significant functions that provide protection to onsite workers. The GSHe essential function is to provide helium to support process functions during all phases of facility operations. GSHe helium is used to purge the cask and the MCO in order to maintain their internal atmospheres below hydrogen flammability concentrations. The GSHe also supplies helium to purge the PWC lines and components and the VPS vacuum pump.

FARWICK, C.C.

1999-07-06T23:59:59.000Z

255

Interim Report on the Optimization and Feasibility Studies for the Neutron Detection without Helium-3 Project  

SciTech Connect

This report provides the status and results of the first year's effort in modeling and simulation to investigate alternatives to helium-3 for neutron detection in safeguards applications.

Ely, James H.

2012-03-19T23:59:59.000Z

256

EPRI NMAC Maintainability Review of the International Gas-Turbine Modular Helium Reactor Power Conversion Unit  

Science Conference Proceedings (OSTI)

This report provides information of interest to the designers of modular helium-reactor-driven gas turbines and persons considering the purchase of this type of plant.

2001-02-01T23:59:59.000Z

257

Ultra high vacuum pumping system and high sensitivity helium leak detector  

DOE Patents (OSTI)

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10{sup {minus}13} atm cc/s. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces back streaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium. 2 figs.

Myneni, G.R.

1997-12-30T23:59:59.000Z

258

Ultra high vacuum pumping system and high sensitivity helium leak detector  

DOE Patents (OSTI)

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10.sup.-13 atm cc s.sup.-1. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces backstreaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium.

Myneni, Ganapati Rao (Yorktown, VA)

1997-01-01T23:59:59.000Z

259

THE CONSTRUCTION AND TESTING OF A DOUBLE ACTING BELLOWS LIQUID HELIUM PUMP  

E-Print Network (OSTI)

Helium Pump (Without Heat Exchanger S Control Dewar) (LIQUIDcavities from the exit heat exchanger. Both of these valvescopper tube split flow heat exchanger which shares a common

Burns, W.A.

2010-01-01T23:59:59.000Z

260

Fatigue Crack Closure and Corrosion Fatigue in Al 7075 Alloy Using ...  

Science Conference Proceedings (OSTI)

Traditional methods to quantify crack closure load, such as load-displacement curves, are not very accurate. In this study, the degree of crack closure through ...

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

A Study on Fatigue-Crack-Deformation Behavior Following a Single ...  

Science Conference Proceedings (OSTI)

Apr 27, 2009 ... Width. Using this method, the respective crack—opening load (COL) at various crack-growth stages can be determined ?om the curve of the ...

262

Induction Heating Stress Improvement Effectiveness on Crack Growth in Operating Plants (BWRVIP-61)  

Science Conference Proceedings (OSTI)

New reports of intergranular stress corrosion cracking prompted this review of factors that could influence the performance of the pipe cracking remedy known as induction heating stress improvement.

1999-01-27T23:59:59.000Z

263

Assessment of Crack in Corrosion Defects in Natural Gas Transmission Pipelines.  

E-Print Network (OSTI)

??Pipelines are one of the safest forms of transportation for oil and gas. However, pipelines may experience some defects, such as cracks, corrosion and cracks… (more)

Hosseini, Seyed Aliakbar

2010-01-01T23:59:59.000Z

264

Results of crack-arrest tests on two irradiated high-copper welds  

SciTech Connect

The objective of this study was to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288{degree}C to an average fluence of 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). Evaluation of the results shows that the neutron-irradiation-induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves (for the range of test temperatures covered) did not seem to have been altered by irradiation compared to those of the ASME K{sub Ia} curve. 9 refs., 21 figs., 10 tabs.

Iskander, S.K.; Corwin, W.R.; Nanstead, R.K. (Oak Ridge National Lab., TN (USA))

1990-12-01T23:59:59.000Z

265

Helium measurements of pore-fluids obtained from SAFOD drillcore  

SciTech Connect

{sup 4}He accumulated in fluids is a well established geochemical tracer used to study crustal fluid dynamics. Direct fluid samples are not always collectable; therefore, a method to extract rare gases from matrix fluids of whole rocks by diffusion has been adapted. Helium was measured on matrix fluids extracted from sandstones and mudstones recovered during the San Andreas Fault Observatory at Depth (SAFOD) drilling in California, USA. Samples were typically collected as subcores or from drillcore fragments. Helium concentration and isotope ratios were measured 4-6 times on each sample, and indicate a bulk {sup 4}He diffusion coefficient of 3.5 {+-} 1.3 x 10{sup -8} cm{sup 2}s{sup -1} at 21 C, compared to previously published diffusion coefficients of 1.2 x 10{sup -18} cm{sup 2}s{sup -1} (21 C) to 3.0 x 10{sup -15} cm{sup 2}s{sup -1} (150 C) in the sands and clays. Correcting the diffusion coefficient of {sup 4}He{sub water} for matrix porosity ({approx}3%) and tortuosity ({approx}6-13) produces effective diffusion coefficients of 1 x 10{sup -8} cm{sup 2}s{sup -1} (21 C) and 1 x 10{sup -7} (120 C), effectively isolating pore fluid {sup 4}He from the {sup 4}He contained in the rock matrix. Model calculations indicate that <6% of helium initially dissolved in pore fluids was lost during the sampling process. Complete and quantitative extraction of the pore fluids provide minimum in situ porosity values for sandstones 2.8 {+-} 0.4% (SD, n=4) and mudstones 3.1 {+-} 0.8% (SD, n=4).

Ali, S.; Stute, M.; Torgersen, T.; Winckler, G.; Kennedy, B.M.

2010-04-15T23:59:59.000Z

266

A pencil beam algorithm for helium ion beam therapy  

Science Conference Proceedings (OSTI)

Purpose: To develop a flexible pencil beam algorithm for helium ion beam therapy. Dose distributions were calculated using the newly developed pencil beam algorithm and validated using Monte Carlo (MC) methods. Methods: The algorithm was based on the established theory of fluence weighted elemental pencil beam (PB) kernels. Using a new real-time splitting approach, a minimization routine selects the optimal shape for each sub-beam. Dose depositions along the beam path were determined using a look-up table (LUT). Data for LUT generation were derived from MC simulations in water using GATE 6.1. For materials other than water, dose depositions were calculated by the algorithm using water-equivalent depth scaling. Lateral beam spreading caused by multiple scattering has been accounted for by implementing a non-local scattering formula developed by Gottschalk. A new nuclear correction was modelled using a Voigt function and implemented by a LUT approach. Validation simulations have been performed using a phantom filled with homogeneous materials or heterogeneous slabs of up to 3 cm. The beams were incident perpendicular to the phantoms surface with initial particle energies ranging from 50 to 250 MeV/A with a total number of 10{sup 7} ions per beam. For comparison a special evaluation software was developed calculating the gamma indices for dose distributions. Results: In homogeneous phantoms, maximum range deviations between PB and MC of less than 1.1% and differences in the width of the distal energy falloff of the Bragg-Peak from 80% to 20% of less than 0.1 mm were found. Heterogeneous phantoms using layered slabs satisfied a {gamma}-index criterion of 2%/2mm of the local value except for some single voxels. For more complex phantoms using laterally arranged bone-air slabs, the {gamma}-index criterion was exceeded in some areas giving a maximum {gamma}-index of 1.75 and 4.9% of the voxels showed {gamma}-index values larger than one. The calculation precision of the presented algorithm was considered to be sufficient for clinical practice. Although only data for helium beams was presented, the performance of the pencil beam algorithm for proton beams was comparable. Conclusions: The pencil beam algorithm developed for helium ions presents a suitable tool for dose calculations. Its calculation speed was evaluated to be similar to other published pencil beam algorithms. The flexible design allows easy customization of measured depth-dose distributions and use of varying beam profiles, thus making it a promising candidate for integration into future treatment planning systems. Current work in progress deals with RBE effects of helium ions to complete the model.

Fuchs, Hermann; Stroebele, Julia; Schreiner, Thomas; Hirtl, Albert; Georg, Dietmar [Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); PEG MedAustron, 2700 Wiener Neustadt (Austria); Department of Nuclear Medicine, Medical University of Vienna, 1090 Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria)

2012-11-15T23:59:59.000Z

267

Cracking in liquid petroleum gas Horton spheres  

Science Conference Proceedings (OSTI)

A gas processing plant on the western coast of India produces sweet gas after processing sour natural gas. Liquid petroleum gas (LPG) is recovered from the sweet gas. The LPG, containing a H{sub 2}S concentration of 10 ppm to 20 ppm, is stored in Horton spheres, each 17 m in diameter with a capacity of {minus}27 C to 55 C. Horton spheres for containing liquid petroleum gas (LPG) were fabricated on-site using prestressed plates of high-strength carbon steel (CS) SA 537 Class-1 with post-weld heat treatment. High-residual tensile stresses and hydrogen absorption from H{sub 2}S present in LPG could be the cause of cracking at weld and heat-affected zone interfaces at high hardness locations. Recommendations are given for inspection and use of lower-strength CS and improved welding procedures.

Trivedi, D.K. Gupta, S.C. [Oil and Natural Gas Corp., Surat (India). Hazari Gas Processing Complex

1997-07-01T23:59:59.000Z

268

Gas Diffusion in Metals: Fundamental Study of Helium-Point Defect Interactions in Iron and Kinetics of Hydrogen Desorption from Zirconium Hydride  

E-Print Network (OSTI)

Gas Diffusion in Metals: Fundamental Study of Helium-PointGas Diffusion in Metals: Fundamental Study of Helium-Point138 8.1.1 Fundamental study of helium-point defect

Hu, Xunxiang

2013-01-01T23:59:59.000Z

269

THE NON-CONSTANT CTOD/CTOA IN CRACK PROPAGATION  

SciTech Connect

Unlike the common belief that crack propagation behavior can be predicted successfully by employing fracture criteria based on a constant crack tip opening displacement or angle (CTOD/CTOA), this paper shows that the initially non-constant portion of the CTOD/CTOA plays an essential role in predicting the fracture load for a growing crack. Three- and two-dimensional finite element analyses indicate that a severe underestimate of the experimental load vs. crack extension curve would occur if a constant CTOD/CTOA criterion is used. However, the use of a simplified, bilinear CTOD/CTOA criterion including its non-constant portion will closely duplicate the test data. Furthermore, as a result of using the experimental data from J-integral test with various crack length to specimen width ratios (a/W), it is demonstrated that the CTOD/CTOA is crack tip constraint dependent. The initially higher values of the CTOD/CTOA are in fact a natural consequence of crack growth process which is refl ected by the J-resistance curve and its slope (tearing modulus).

LAM, POH-SANG

2004-07-19T23:59:59.000Z

270

Analysis of Alloy 600 and X-750 stress corrosion cracks  

Science Conference Proceedings (OSTI)

A few months ago, KAPL evidence supported the view that Primary or Pure Water Stress Corrosion Cracking (PWSCC) of Alloy 600 results from a hydrogen mechanism. Figure 1 shows an Analytical Electron Microscope (AEM) analysis of a stress corrosion crack (SCC) crack in an A600 split tube U-bend specimen exposed to primary water at 338{degree}C (640{degrees}F) for 462 days. The features which appear to confirm a hydrogen mechanism are: (1) A very narrow (< 200 {angstrom}) crack with a sharp tip, nearly free of deposits. (2) No evidence of severe plastic deformation in the region immediately ahead of the crack tip. (3) A line of small voids preceding the main crack tip, of which the largest is about 5 x 10{sup {minus}6} cm in length. Shen and Shewmon proposed that PWSCC of Alloy 600 occurs due to small microvoids ahead of a main crack tip. The hypothesis is that such voids result from pockets of methane gas formed by the reaction of atomic hydrogen with carbon in the base metal. The voids are about 10 x 10{sup {minus}6} cm diameter, approximately a factor of 2 larger than the largest voids.

Thompson, C.D.; Lewis, N.; Krasodomski, H.

1993-06-01T23:59:59.000Z

271

Helium-Cooled Refractory Alloys First Wall and Blanket Evaluation  

Science Conference Proceedings (OSTI)

Under the APEX program the He-cooled system design task is to evaluate and recommend high power density refractory alloy first wall and blanket designs and to recommend and initiate tests to address critical issues. We completed the preliminary design of a helium-cooled, W-5Re alloy, lithium breeder design and the results are reported in this paper. Many areas of the design were assessed, including material selection, helium impurity control, and mechanical, nuclear and thermal hydraulics design, and waste disposal, tritium and safety design. System study results show that at a closed cycle gas turbine (CCGT) gross thermal efficiency of 57.5%, a superconducting coil tokamak reactor, with an aspect ratio of 4, and an output power of 2 GWe, can be projected to have a cost of electricity at 54.6 mill/kWh. Critical issues were identified and we plan to continue the design on some of the critical issues during the next phase of the APEX design study.

Wong, C.P.C.; Nygren, R.E.; Baxi, C.B.; Fogarty, P.; Ghoniem, N.; Khater, H.; McCarthy, K.; Merrill, B.; Nelson, B.; Reis, E.E.; Sharafat, S.; Schleicher, R.; Sze, D.K.; Ulrickson, M.; Willms, S.; Youssef, M.; Zinkel, S.

1999-08-01T23:59:59.000Z

272

Improved load ratio method for predicting crack length  

SciTech Connect

The elastic compliance from unloading/reloading sequences in a load-displacement record estimates well crack length in elastic-plastic fracture toughness tests of compact tension [C(T)] and bending type specimens. The need for partial unloading of the specimen makes it difficult to run the test under static loading and impossible under either dynamic loading or very high temperatures. Furthermore, fracture toughness testing in which crack length is determined from elastic compliance requires high precision testing equipment and highly skilled technicians. As a result, such tests are confined usually to research laboratories and seldom used under production settings. To eliminate these problems, an improved load ratio method of predicting crack length is proposed that utilizes only the recorded load versus load-line displacement curve (or load versus crack-mouth-opening displacement curve) without unloading/reloading sequences. As a result, the instrumentation is much simpler than in the elastic compliance or potential drop methods. If only a monotonic load-displacement record is to be measured the fracture toughness test becomes almost as simple to perform as a tension test. The method described here improves in three ways the ``original load ratio method`` proposed by Hu et al. First, a blunting term is added to the crack length before maximum load. Second, a strain hardening correction is included after maximum load. And, third, the initial crack length and the physical (final) crack length measured at the end of the test serve to anchor the predicted crack lengths, forcing agreement between predicted and measured values. The method predicts crack extension with excellent accuracy in specimens fabricated from A302, A508, and A533B piping and pressure vessel steels, A588 and A572 structural steels, and HY-80 ship steel.

Chen, X.; Albrecht, P. [Univ. of Maryland, College Park, MD (United States). Inst. for Systems Research; Wright, W. [Federal Highway Administration, McLean, VA (United States). Turner-Fairbank Highway Research Center; Joyce, J.A. [Naval Academy, Annapolis, MD (United States). Mechanical Engineering Dept.

1995-04-01T23:59:59.000Z

273

Prediction of Reflection Cracking in Hot Mix Asphalt Overlays  

E-Print Network (OSTI)

Reflection cracking is one of the main distresses in hot-mix asphalt (HMA) overlays. It has been a serious concern since early in the 20th century. Since then, several models have been developed to predict the extent and severity of reflection cracking in HMA overlays. However, only limited research has been performed to evaluate and calibrate these models. In this dissertation, mechanistic-based models are calibrated to field data of over 400 overlay test sections to produce a design process for predicting reflection cracks. Three cracking mechanisms: bending, shearing traffic stresses, and thermal stress are taken into account to evaluate the rate of growth of the three increasing levels of distress severity: low, medium, and high. The cumulative damage done by all three cracking mechanisms is used to predict the number of days for the reflection crack to reach the surface of the overlay. The result of this calculation is calibrated to the observed field data (severity and extent) which has been fitted with an S-shaped curve. In the mechanistic computations, material properties and fracture-related stress intensity factors are generated using efficient Artificial Neural Network (ANN) algorithms. In the bending and shearing traffic stress models, the traffic was represented by axle load spectra. In the thermal stress model, a recently developed temperature model was used to predict the temperature at the crack tips. This process was developed to analyze various overlay structures. HMA overlays over either asphalt pavement or jointed concrete pavement in all four major climatic zones are discussed in this dissertation. The results of this calculated mechanistic approach showed its ability to efficiently reproduce field observations of the growth, extent, and severity of reflection cracking. The most important contribution to crack growth was found to be thermal stress. The computer running time for a twenty-year prediction of a typical overlay was between one and four minutes.

Tsai, Fang-Ling

2010-12-01T23:59:59.000Z

274

THERMAL PERFORMANCE OF A DUAL-CHANNEL, HELIUM-COOLED, TUNGSTEN HEAT EXCHANGER  

E-Print Network (OSTI)

THERMAL PERFORMANCE OF A DUAL-CHANNEL, HELIUM-COOLED, TUNGSTEN HEAT EXCHANGER Dennis L. Youchison-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications-channel, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore

California at Los Angeles, University of

275

The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle  

E-Print Network (OSTI)

The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle Matthias R. Aellig Alamos National Lab., Los Alamos, NM 87545 Abstract We investigate the helium abundance in the solar wind of 1994 and early 2000 are analyzed. In agreement with similar work for previous solar cycles, we find

Richardson, John

276

Examination of cracked turbine discs from nuclear power plants  

SciTech Connect

Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station (BWR), and on two failed turbine discs from the Yankee-Rowe Nuclear Power Station (PWR). The Yankee-Rowe discs were subjected to SEM/EDAX, uniaxial tension tests, hardness testing, notch sensitivity tests, and environmental notched tensile tests. The results of this investigation support the model whereby the cracks initiated at startup of the turbine, probably from H/sub 2/S produced by hydrolysis of MoS/sub 2/, and grew at a rate consistent with published data for propagation of cracks in pure steam.

Czajkowski, C.J.; Weeks, J.R.

1983-03-01T23:59:59.000Z

277

Shale oil cracking. 2. Effect on oil composition  

DOE Green Energy (OSTI)

Results from spectroscopic investigations are presented that demonstrate the effect of oil cracking on shale oil composition. Techniques used include infrared spectroscopy, capillary column gas chromatography/mass spectroscopy and /sup 13/C nuclear magnetic resonance. We show that cracking causes an increase in aromatic and alkene content of the oil. We compare our results for oils prepared in the laboratory with oils prepared in the TOSCO-II semi-works and in modified and true-in-situ combustion retorts. We demonstrate that the napthalene/2-methyl-naphthalene ratio is a good indicator of cracking conditions in an oil shale retort.

Burnham, A.K.; Sanborn, R.H.; Crawford, R.W.; Newton, J.C.; Happe, J.A.

1980-08-01T23:59:59.000Z

278

Evaluation of Cracks in ABB HK Arc Chutes  

Science Conference Proceedings (OSTI)

The nuclear power industry has a number of medium voltage (5 Kv-15 Kv) ABB HK air-magnetic circuit breakers with cracks in various places on the ceramic liner plate and cold-molded asbestos portions of the arc chutes. These cracks may or may not be cosmetic. This "jump gap crack" issue has been discussed in several ABB circuit breaker users group meetings. Five utilities (Brunswick, Seabrook, TVA, Duke, and Vogtle) have previously expressed interest in this issue. The present ABB Quality Assurance Proced...

2005-05-03T23:59:59.000Z

279

Gas Diffusion in Metals: Fundamental Study of Helium-Point Defect Interactions in Iron and Kinetics of Hydrogen Desorption from Zirconium Hydride  

E-Print Network (OSTI)

Ullmaier. Helium and hydrogen effects on the embrittlementT. Troev. The effect of hydrogen and helium on microvoidp. 1-51. M. Steinbruck. Hydrogen absorption by zirconium

Hu, Xunxiang

2013-01-01T23:59:59.000Z

280

Regional And Local Trends In Helium Isotopes, Basin And Range Province,  

Open Energy Info (EERE)

And Local Trends In Helium Isotopes, Basin And Range Province, And Local Trends In Helium Isotopes, Basin And Range Province, Western North America- Evidence For Deep Permeable Pathways Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Regional And Local Trends In Helium Isotopes, Basin And Range Province, Western North America- Evidence For Deep Permeable Pathways Details Activities (1) Areas (1) Regions (0) Abstract: Fluids from the western margin of the Basin and Range have helium isotope ratios as high as ~6-7 Ra, indicating a strong mantle melt influence and consistent with recent and current volcanic activity. Moving away from these areas, helium isotope ratios decrease rapidly to 'background' values of around 0.6 Ra, and then gradually decrease toward the east to low values of ~0.1 Ra at the eastern margin of the Basin and

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Unique method for liquid nitrogen precooling of a plate fin heat exchanger in a helium refrigeration cycle  

E-Print Network (OSTI)

Unique method for liquid nitrogen precooling of a plate fin heat exchanger in a helium refrigeration cycle

Weber, T B; Howell, G; Racine, M; Weisend, J G

2004-01-01T23:59:59.000Z

282

On the Sensitivity of Massive Star Nucleosynthesis and Evolution to Solar Abundances and to Uncertainties in Helium Burning Reaction Rates  

E-Print Network (OSTI)

We explore the dependence of pre-supernova evolution and supernova nucleosynthesis yields on the uncertainties in helium burning reaction rates. Using the revised solar abundances of Lodders (2003) for the initial stellar composition, instead of those of Anders & Grevesse (1989), changes the supernova yields and limits the constraints that those yields place on the 12C(a,g)16O reaction rate. The production factors of medium-weight elements (A = 16-40) were found to be in reasonable agreement with observed solar ratios within the current experimental uncertainties in the triple alpha reaction rate. Simultaneous variations by the same amount in both reaction rates or in either of them separately, however, can induce significant changes in the central 12C abundance at core carbon ignition and in the mass of the supernova remnant. It therefore remains important to have experimental determinations of the helium burning rates so that their ratio and absolute values are known with an accuracy of 10% or better.

Clarisse Tur; Alexander Heger; Sam M. Austin

2007-05-30T23:59:59.000Z

283

Strategies for planar crack propagation based on the concept of material forces  

Science Conference Proceedings (OSTI)

This paper presents a computational framework for the simulation of planar crack growth (including kinking) driven by "material forces". An evolution law for the crack tip position is formulated, which is shown to give rise to different propagation strategies ... Keywords: Configurational forces, Crack curving, Crack propagation

Jim Brouzoulis; Fredrik Larsson; Kenneth Runesson

2011-03-01T23:59:59.000Z

284

Crack coalescence in rock-like material under cycling loading  

E-Print Network (OSTI)

A total of 170 tests (68 tests for monotonic loading, 102 tests for cyclic loading) have been performed to investigate crack initiation, propagation and coalescence. The specimens have two pre-existing flaws which are ...

Ko, Tae Young, 1973-

2005-01-01T23:59:59.000Z

285

Evaluation of Stress Corrosion Cracking Susceptibility of Drill Pipe ...  

Science Conference Proceedings (OSTI)

G-105 and S-135 grades of drill pipe steels have been used to study the effect of temperature and solution chemistry on the stress corrosion cracking behavior of ...

286

SLAC National Accelerator Laboratory - SLAC Research Cracks Puzzle...  

NLE Websites -- All DOE Office Websites (Extended Search)

Press Release Archive SLAC Research Cracks Puzzle of Enzyme Critical to Food Supply November 17, 2011 Menlo Park, Calif. - If we could make plant food from nitrogen the way nature...

287

3D Characterization and Modeling of Fatigue Cracks  

Science Conference Proceedings (OSTI)

The HEDM and CT are performed with high energy x-rays at the Advanced Photon Source (APS). One set of LSHR specimens has small cracks on the order of ...

288

Cracked shaft detection and diagnostics: A literature review  

E-Print Network (OSTI)

ABSTRACT—Cracks in shafts have long been identified as factors limiting the safe and reliable operation of turbomachines. They can sometimes result in catastrophic failure of equipment (rotor bursts) and, more often, in costly process upsets, repairs and premature scrapping and replacement of equipment. Cracked shafts still pose a significant and real threat to equipment in spite of the great advances made in the areas of metallurgy, manufacturing and design. In the past two decades, much research and many resources have gone into developing various on-line and off-line diagnostic techniques to effectively detect cracks before they cause serious damage. Because of the enormous amount of ongoing research in this area (more than 500 technical papers have been published in English alone in the past 30 years), there is a real need to periodically condense and summarize the information. This paper reviews literature on cracked shaft detection and diagnostics published after 1990.

Giridhar Sabnavis; R. Gordon Kirk; Mary Kasarda; Dane Quinn; Giridhar Sabnavis; R. Gordon Kirk; Mary Kasarda; Dane Quinn

2004-01-01T23:59:59.000Z

289

Effect of Oxygen Potential on Crack Growth in Alloy 617  

Science Conference Proceedings (OSTI)

Static crack growth rate increases from 4 x 10-9 m/sec to 4 x 10-8 m/sec when the oxygen concentration decreases from .001 to .0000001 atm. Proceedings ...

290

Process to minimize cracking of pyrolytic carbon coatings  

DOE Patents (OSTI)

Carbon-coated microspheroids useful as fuels in nuclear reactors are produced with a low percentage of cracked coatings and are imparted increased strength and mechanical stability characteristics by annealing immediately after the carbon coating processes.

Lackey, Jr., Walter J. (Oak Ridge, TN); Sease, John D. (Knoxville, TN)

1978-01-01T23:59:59.000Z

291

Temperature dependence of the intrinsic small fatigue crack growth behavior in Ni-base superalloys based on measurement of crack closure  

Science Conference Proceedings (OSTI)

The effect of temperature on the small fatigue crack growth behavior of a single crystal and directionally solidified Ni-base superalloys was investigated at temperatures between 873 to 1,123 K by measuring the crack closure. The results were also compared with those of the physically long crack. It was found that the propagation resistance and the fatigue threshold of the long cracks increased with temperature in all the materials. The long crack growth rates at three temperatures were approximately represented by an unique curve, after taking account of crack closure level and elastic modulus. In contrast, the small crack growth resistance decreased with temperature even when the crack closure phenomenon was taken into consideration. Furthermore, the small fatigue cracks exhibited considerably higher growth rates than the long cracks at a given effective stress intensity factor range and also grew under effective stress intensity factor ranges below the long crack threshold. The factors responsible for the lack of similitude in propagation rates between small and long cracks were also discussed, based on these observations and the chemical analysis near the crack tip using the electron probe microanalyzer.

Okazaki, M.; Yamada, H. [Nagaoka Univ. of Technology (Japan). Dept. of Mechanical Engineering; Nohmi, S. [Kawasaki Heavy Industries Co. Ltd., Akashi (Japan)

1996-04-01T23:59:59.000Z

292

Nucleation and growth of cracks in vitreous-bonded aluminum oxide at elevated temperatures  

Science Conference Proceedings (OSTI)

The nucleation and growth of cracks was studied at elevated temperatures on a grade of vitreous-bonded aluminium oxide that contained approx. =8 vol% glass at the grain boundaries. Cracks were observed to nucleate within the vitreous phase, close to the tensile surface of the flexural test specimens used in these experiments. Crack nucleation occurred at a strain of approx. =0.08% to 0.12% which corresponded to a crack nucleation time of approx. =35% of the time to failure by creep rupture. Once nucleated, cracks propagated along grain boundaries, as long as the stress for crack propagation was maintained. The crack velocity for cracks that were nucleated by the creep process was found to be linearly proportional to the apparent stress intensity factor, whereas for cracks that were nucleated by indentation, the crack velocity was proportional to the fourth power of the apparent stress intensity factor.

Jakus, K.; Wiederhorn, S.M.; Hockey, B.J.

1986-10-01T23:59:59.000Z

293

Reliability Centered Lifetime Prediction of Environmentally Assisted Cracking  

Science Conference Proceedings (OSTI)

This report describes the results of joint research sponsored by EPRI in cooperation with Tohoku University and a number of Japanese organizations to address the issue of environmentally assisted cracking (EAC) in boiling water reactors (BWRs) and pressurized water reactors (PWRs). The term EAC includes intergranular stress corrosion cracking and corrosion fatigue. The goal of this project was to develop a fundamental understanding of processes controlling EAC of stainless steels and nickel-base alloys i...

2003-09-02T23:59:59.000Z

294

Crack reconstruction using a level-set strategy  

Science Conference Proceedings (OSTI)

We present a level-set based technique to recover key characteristics of a defect or crack (e.g. location, length and shape) in a two-dimensional material from boundary electrical measurements. The key feature of this work is to extend the usual level-set ... Keywords: 02.30.Zz, 41.20.Cv, 42.30.Wb, Crack reconstruction, Electrical impedance tomography, Level-sets

Diego Álvarez; Oliver Dorn; Natalia Irishina; Miguel Moscoso

2009-09-01T23:59:59.000Z

295

Pion Electroproduction form Helium 3, Deuterium, and Hydrogen  

DOE Green Energy (OSTI)

A series of measurements for pion electroproduction from helium-3, deuterium, and hydrogen were completed at the Thomas Jefferson National Accelerator Facility by the NucPi Collaboration. E91003 began taking data in February 1998 and was completed in April 1998. The longitudinal and transverse parts of the differential cross section were extracted, by means of a Rosenbluth type separation, in the direction parallel to the virtual photon, at Q 2 = 0.4 GeV 2 , for W = 1.15 and W = 1.6 GeV. The mass dependence of the longitudinal cross section should provide insight into the surprising apparent absence of any significant cross section enhancement due to excess pions in the nuclear medium.

S. Avery

2002-05-01T23:59:59.000Z

296

Ionization of hydrogen and ionized helium by slow antiprotons  

E-Print Network (OSTI)

We study the ionization process involving antiproton and hydrogen in the energy range between 0.1 keV to 500 keV, using single center close coupling approximation. We construct the scattering wave function using B-spline bases. The results obtained for ionization of atomic hydrogen are compared with other existing theoretical calculations as well as with the available experimental data. The present results are found to be encouraging. We also employed this method to study the ionization of ionized helium in the energy range between 1 and 500 keV. On comparision, the present results are found to interpret well the cross section values calculated using other theories.

Sahoo, S; Walters, H R J

2004-01-01T23:59:59.000Z

297

Nuclear fusion in muonic deuterium-helium complex  

E-Print Network (OSTI)

Experimental study of the nuclear fusion reaction in charge-asymmetrical d-mu-3He complex is presented. The 14.6 MeV protons were detected by three pairs of Si(dE-E) telescopes placed around the cryogenic target filled with the deuterium + helium-3 gas at 34 K. The 6.85 keV gamma rays emitted during the de-excitation of d-mu-3He complex were detected by a germanium detector. The measurements were performed at two target densities, 0.0585 and 0.169 (relative to liquid hydrogen density) with an atomic concentration of 3He c=0.0469. The values of the effective rate of nuclear fusion in d-mu-3He was obtained for the first time, and the J=0 nuclear fusion rate in d-mu-3He was derived.

V. M. Bystritsky; M. Filipowicz; V. V. Gerasimov; P. E. Knowles; F. Mulhauser; N. P. Popov; V. A. Stolupin; V. P. Volnykh; J. Wozniak

2005-06-22T23:59:59.000Z

298

Superconducting cable cooling system by helium gas at two pressures  

DOE Patents (OSTI)

Thermally contacting, oppositely streaming, cryogenic fluid streams in the same enclosure in a closed cycle that changes the fluid from a cool high pressure helium gas to a cooler reduced pressure helium gas in an expander so as to be at different temperature ranges and pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T.sub.1. By first circulating the fluid from a refrigerator at one end of the line as a cool gas at a temperature range T.sub.2 to T.sub.3 in the go leg, then circulating the gas through an expander at the other end of the line where the gas becomes a cooler gas at a reduced pressure and at a reduced temperature T.sub.4 and finally by circulating the cooler gas back again to the refrigerator in a return leg at a temperature range T.sub.4 to T.sub.5, while in thermal contact with the gas in the go leg, and in the same enclosure therewith for compression into a higher pressure gas at T.sub.2 in a closed cycle, where T.sub.2 >T.sub.3 and T.sub.5 >T.sub.4, the fluid leaves the enclosure in the go leg as a gas at its coldest point in the go leg, and the temperature distribution is such that the line temperature decreases along its length from the refrigerator due to the cooling from the gas in the return leg.

Dean, John W. (Los Alamos, NM)

1977-01-01T23:59:59.000Z

299

Helium measurements of pore-fluids obtained from SAFOD drillcore  

Science Conference Proceedings (OSTI)

{sup 4}He accumulated in fluids is a well established geochemical tracer used to study crustal fluid dynamics. Direct fluid samples are not always collectable; therefore, a method to extract rare gases from matrix fluids of whole rocks by diffusion has been adapted. Helium was measured on matrix fluids extracted from sandstones and mudstones recovered during the San Andreas Fault Observatory at Depth (SAFOD) drilling in California, USA. Samples were typically collected as subcores or from drillcore fragments. Helium concentration and isotope ratios were measured 4-6 times on each sample, and indicate a bulk {sup 4}He diffusion coefficient of 3.5 {+-} 1.3 x 10{sup -8} cm{sup 2}s{sup -1} at 21 C, compared to previously published diffusion coefficients of 1.2 x 10{sup -18} cm{sup 2}s{sup -1} (21 C) to 3.0 x 10{sup -15} cm{sup 2}s{sup -1} (150 C) in the sands and clays. Correcting the diffusion coefficient of {sup 4}He{sub water} for matrix porosity ({approx}3%) and tortuosity ({approx}6-13) produces effective diffusion coefficients of 1 x 10{sup -8} cm{sup 2}s{sup -1} (21 C) and 1 x 10{sup -7} (120 C), effectively isolating pore fluid {sup 4}He from the {sup 4}He contained in the rock matrix. Model calculations indicate that fluids was lost during the sampling process. Complete and quantitative extraction of the pore fluids provide minimum in situ porosity values for sandstones 2.8 {+-} 0.4% (SD, n=4) and mudstones 3.1 {+-} 0.8% (SD, n=4).

Ali, S.; Stute, M.; Torgersen, T.; Winckler, G.; Kennedy, B.M.

2010-04-15T23:59:59.000Z

300

Electron correlation in two-photon double ionization of helium from attosecond to FEL pulses  

SciTech Connect

We investigate the role of electron correlation in the two-photon double ionization of helium for ultrashort pulses in the extreme ultraviolet (XUV) regime with durations ranging from a hundred attoseconds to a few femtoseconds. We perform time-dependent ab initio calculations for pulses with mean frequencies in the so-called 'sequential' regime ({Dirac_h}{omega} > 54.4 eV). Electron correlation induced by the time correlation between emission events manifests itself in the angular distribution of the ejected electrons, which strongly depends on the energy sharing between them. We show that for ultrashort pulses two-photon double ionization probabilities scale non-uniformly with pulse duration depending on the energy sharing between the electrons. Most interestingly we find evidence for an interference between direct ('nonsequential') and indirect ('sequential') double photoionization with intermediate shake-up states, the strength of which is controlled by the pulse duration. This observation may provide a route towards measuring the pulse duration of x-ray free-electron laser (XFEL) pulses.

Collins, Lee [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Electron correlation in two-photon double ionization of helium from attosecond to FEL pulses  

SciTech Connect

We investigate the role of electron correlation in the two-photon double ionization of helium for ultrashort pulses in the extreme ultraviolet (XUV) regime with durations ranging from a hundred attoseconds to a few femtoseconds. We perform time-dependent ab initio calculations for pulses with mean frequencies in the so-called 'sequential' regime ({Dirac_h}{omega} > 54.4 eV). Electron correlation induced by the time correlation between emission events manifests itself in the angular distribution of the ejected electrons, which strongly depends on the energy sharing between them. We show that for ultrashort pulses two-photon double ionization probabilities scale non-uniformly with pulse duration depending on the energy sharing between the electrons. Most interestingly we find evidence for an interference between direct ('nonsequential') and indirect ('sequential') double photoionization with intermediate shake-up states, the strength of which is controlled by the pulse duration. This observation may provide a route towards measuring the pulse duration of x-ray free-electron laser (XFEL) pulses.

Collins, Lee [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

302

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

DOE Patents (OSTI)

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.

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

2003-02-11T23:59:59.000Z

303

Forced flow supercritical helium in a closed heat transfer loop subjected to pulsed heat loads  

Science Conference Proceedings (OSTI)

The superconducting magnets of the tokamak JT-60SA are cooled by means of forced flows of supercritical helium at 4.4 K and 0.5 MPa. The closed loops transfer heat from the magnets to the refrigerator through heat exchangers immersed into a saturated liquid helium bath. An experimental loop was designed to represent a 1/20 scaled down mock-up of JT-60SA central solenoid cooling circuits. This design for keeping the same transit times in the helium circuits

2012-01-01T23:59:59.000Z

304

Apparatus to measure liquid helium boil-off from low-loss superconducting current leads  

DOE Green Energy (OSTI)

A low-loss liquid helium dewar was constructed to measure the liquid helium boil-off rate from high-temperature superconducting current leads. The dewar has a measured background heat leakage rate of 12 mW. Equations calculating the heat leakage rate from the measured vapor mass flow rate in liquid helium boil-off experiments are derived. Parameters that affect the experiments, such as density ratio, absolute pressure, and rate of pressure variation, are discussed. This study is important as superconducting current leads may be used in superconducting magnetic energy storage systems.

Cha, Y.S.; Niemann, R.C.; Hull, J.R. [Argonne National Lab., IL (United States). Energy Technology Div.

1995-06-01T23:59:59.000Z

305

DEUTERIUM, TRITIUM, AND HELIUM DESORPTION FROM AGED TITANIUM TRITIDES. PART I.  

DOE Green Energy (OSTI)

Six new samples of tritium-aged bulk titanium have been examined by thermal desorption and isotope exchange chemistry. The discovery of a lower temperature hydrogen desorption state in these materials, previously reported, has been confirmed in one of the new samples. The helium release of the samples shows the more severe effects obtained from longer aging periods, i.e. higher initial He/M ratios. Several of the more aged samples were spontaneously releasing helium. Part I will discuss the new results on the new lower temperature hydrogen desorption state found in one more extensively studied sample. Part II will discuss the hydrogen/helium release behavior of the remaining samples.

Shanahan, K; Jeffrey Holder, J

2006-07-10T23:59:59.000Z

306

DEUTERIUM, TRITIUM, AND HELIUM DESORPTION FROM AGED TITANIUM TRITIDES. PART II.  

DOE Green Energy (OSTI)

Six new samples of tritium-aged bulk titanium have been examined by thermal desorption and isotope exchange chemistry. The discovery of a lower temperature hydrogen desorption state in these materials, previously reported, has been confirmed in one of the new samples. The helium release of the samples shows the more severe effects obtained from longer aging periods, i.e. higher initial He/M ratios. Several of the more aged samples were spontaneously releasing helium. Part I discussed the new results on the new lower temperature hydrogen desorption state found in one more extensively studied sample. Part II will discuss the hydrogen/helium release behavior of the remaining samples.

Shanahan, K; Jeffrey Holder, J

2006-08-17T23:59:59.000Z

307

Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation  

Science Conference Proceedings (OSTI)

This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

Maziasz, P.J.

1985-11-01T23:59:59.000Z

308

A review of irradiation effects on LWR core internal materials - IASCC susceptibility and crack growth rates of austenitic stainless steels.  

SciTech Connect

Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of light water reactor (LWR) pressure vessels because of their relatively high strength, ductility, and fracture toughness. However, exposure to neutron irradiation for extended periods changes the microstructure (radiation hardening) and microchemistry (radiation-induced segregation) of these steels, and degrades their fracture properties. Irradiation-assisted stress corrosion cracking (IASCC) is another degradation process that affects LWR internal components exposed to neutron radiation. The existing data on irradiated austenitic SSs were reviewed to evaluate the effects of key parameters such as material composition, irradiation dose, and water chemistry on IASCC susceptibility and crack growth rates of these materials in LWR environments. The significance of microstructural and microchemistry changes in the material on IASCC susceptibility is also discussed. The results are used to determine (a) the threshold fluence for IASCC and (b) the disposition curves for cyclic and IASCC growth rates for irradiated SSs in LWR environments.

Chopra, O. K.; Roa, A. S.; Environmental Science Division; U.S. NRC

2010-12-15T23:59:59.000Z

309

Stress corrosion cracking of austenitic stainless steel core internal welds.  

SciTech Connect

Microstructural analyses by several advanced metallographic techniques were conducted on austenitic stainless steel mockup and core shroud welds that had cracked in boiling water reactors. Contrary to previous beliefs, heat-affected zones of the cracked Type 304L, as well as 304 SS core shroud welds and mockup shielded-metal-arc welds, were free of grain-boundary carbides, which shows that core shroud failure cannot be explained by classical intergranular stress corrosion cracking. Neither martensite nor delta-ferrite films were present on the grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the core shroud welds were significantly contaminated by oxygen and fluorine, which migrate to grain boundaries. Significant oxygen contamination seems to promote fluorine contamination and suppress thermal sensitization. Results of slow-strain-rate tensile tests also indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of core shroud welds.

Chung, H. M.; Park, J.-H.; Ruther, W. E.; Sanecki, J. E.; Strain, R. V.; Zaluzec, N. J.

1999-04-14T23:59:59.000Z

310

Crack Surface Roughness in Three-Dimensional Random Fuse Networks  

SciTech Connect

Using large system sizes with extensive statistical sampling, we analyze the scaling properties of crack roughness and damage profiles in the three-dimensional random fuse model. The analysis of damage profiles indicates that damage accumulates in a diffusive manner up to the peak load, and localization sets in abruptly at the peak load starting from a uniform damage landscape. The global crack width scales as $W \\sim L^{0.5}$ and is consistent with the scaling of localization length $\\xi \\sim L^{0.5}$ used in the data collapse of damage profiles in the post-peak regime. This consistency between the global crack roughness exponent and the post-peak damage profile localization length supports the idea that the post-peak damage profile is predominantly due to the localization produced by the catastrophic failure, which at the same time results in the formation of the final crack. Finally, the crack width distributions can be collapsed for different system sizes and follow a log-normal distribution.

Nukala, Phani K [ORNL; Zapperi, Stefano [University of La Sapienza, Rome; Simunovic, Srdjan [ORNL

2006-01-01T23:59:59.000Z

311

Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and  

Open Energy Info (EERE)

Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and Steamboat Springs Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and Steamboat Springs Details Activities (3) Areas (3) Regions (0) Abstract: Helium isotope ratios have been measured in geothermal fluids from Iceland, The Geysers, Raft River, Steamboat Springs and Hawaii. These ratios have been interpreted in terms of the processes which supply He in distinct isotopic ratios (i.e. magmatic He, ~10 Ra; atmospheric He, R,sub>a; and crustal He, ~0.1 Ra) and in terms of the processes which can alter the isotopic ratio (hydrologic mixing, U-Th series alpha production and weathering release of crustal He, magma aging and

312

Helium Isotopes In Geothermal And Volcanic Gases Of The Western United  

Open Energy Info (EERE)

Helium Isotopes In Geothermal And Volcanic Gases Of The Western United Helium Isotopes In Geothermal And Volcanic Gases Of The Western United States, I, Regional Variability And Magmatic Origin Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Helium Isotopes In Geothermal And Volcanic Gases Of The Western United States, I, Regional Variability And Magmatic Origin Details Activities (1) Areas (1) Regions (0) Abstract: Helium isotope ratios in gases of thirty hot springs and geothermal wells and of five natural gas wells in the western United States show no relationship to regional conductive heat flow, but do show a correlation with magma-based thermal activity and reservoir fluid temperature (or total convective heat discharge). Gases from high-T (> 200°C) reservoirs have 3He/4He > 2 _ the atmospheric value, with high He

313

Flow of mantle fluids through the ductile lower crust: Helium isotope trends  

E-Print Network (OSTI)

super-imposed on regional trends can identify potentialCrust: Helium Isotope Trends I B. Mack Kennedyl andlMatthijsin the west, a regional trend that correlates with the rates

Kennedy, B. Mack; van Soest, Matthijs C.

2008-01-01T23:59:59.000Z

314

Helium and lead isotope geochemistry of oceanic volcanic rocks from the East Pacific and South Atlantic  

E-Print Network (OSTI)

The isotopic evolution of helium and lead in the Earth is coupled by virtue of their common radioactive parents uranium and thorium. The isotopic signatures in oceanic volcanic rocks provide constraints on the temporal ...

Graham, David W. (David William)

1987-01-01T23:59:59.000Z

315

Flow of mantle fluids through the ductile lower crust: Helium isotope trends  

E-Print Network (OSTI)

of the latter is the Dixie Valley thermal system (Figure 2),that crossed through Dixie Valley revealed a zone of lowsuggesting that the Dixie Valley helium anomaly rellects a

Kennedy, B. Mack; van Soest, Matthijs C.

2008-01-01T23:59:59.000Z

316

Helium/Hydrogen Effects on the Properties of Materials for the APT Target/Blanket Region  

DOE Green Energy (OSTI)

This paper provides a technical basis to rationalize potential synergistic effects among displacement damage and the hydrogen and helium embrittlement processes and suggests that such synergistic effects may be of significant importance to component performance in intense spallation neutron sources.

Louthan, M.R.

1999-11-17T23:59:59.000Z

317

Carburization of austenitic alloys by gaseous impurities in helium  

SciTech Connect

The carburization behavior of Alloy 800H, Inconel Alloy 617 and Hastelloy Alloy X in helium containing various amounts of H/sub 2/, CO, CH/sub 4/, H/sub 2/O and CO/sub 2/ was studied. Corrosion tests were conducted in a temperature range from 649 to 1000/sup 0/C (1200 to 1832/sup 0/F) for exposure time up to 10,000 h. Four different helium environments, identified as A, B, C, and D, were investigated. Concentrations of gaseous impurities were 1500 ..mu..atm H/sub 2/, 450 ..mu..atm CO, 50 ..mu..atm CH/sub 4/ and 50 ..mu..atm H/sub 2/O for Environment A; 200 ..mu..atm H/sub 2/, 100 ..mu..atm CO, 20 ..mu..atm CH/sub 4/, 50 ..mu..atm H/sub 2/O and 5 ..mu..atm CO/sub 2/ for Environment B; 500 ..mu..atm H/sub 2/, 50 ..mu..atm CO, 50 ..mu..atm CH/sub 4/ and < 0.5 ..mu..atm H/sub 2/O for Environment C; and 500 ..mu..atm H/sub 2/, 50 ..mu..atm CO, 50 ..mu..atm CH/sub 4/ and 1.5 ..mu..atm H/sub 2/O for Environment D. Environments A and B were characteristic of high-oxygen potential, while C and D were characteristic of low-oxygen potential. The results showed that the carburization kinetics in low-oxygen potential environments (C and D) were significantly higher, approximately an order of magnitude higher at high temperatures, than those in high-oxygen potential environments (A and B) for all three alloys. Thermodynamic analyses indicated no significant differences in the thermodynamic carburization potential between low- and high-oxygen potential environments. It is thus believed that the enhanced carburization kinetics observed in the low-oxygen potential environments were related to kinetic effects. A qualitatively mechanistic model was proposed to explain the enhanced kinetics. The present results further suggest that controlling the oxygen potential of the service environment can be an effective means of reducing carburization of alloys.

Lai, G.Y.; Johnson, W.R.

1980-03-01T23:59:59.000Z

318

FITNESS-FOR-SERVICE ASSESSMENT FOR A RADIOACTIVE WASTE TANK THAT CONTAINS STRESS CORROSION CRACKS  

SciTech Connect

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The tanks are examined by ultrasonic (UT) methods for thinning, pitting, and stress corrosion cracking in order to assess fitness-for-service. During an inspection in 2002, ten cracks were identified on one of the tanks. Given the location of the cracks (i.e., adjacent to welds, weld attachments, and weld repairs), fabrication details (e.g., this tank was not stress-relieved), and the service history the degradation mechanism was stress corrosion cracking. Crack instability calculations utilizing API-579 guidance were performed to show that the combination of expected future service condition hydrostatic and weld residual stresses do not drive any of the identified cracks to instability. The cracks were re-inspected in 2007 to determine if crack growth had occurred. During this re-examination, one indication that was initially reported as a 'possible perpendicular crack <25% through wall' in 2002, was clearly shown not to be a crack. Additionally, examination of a new area immediately adjacent to other cracks along a vertical weld revealed three new cracks. It is not known when these new cracks formed as they could very well have been present in 2002 as well. Therefore, a total of twelve cracks were evaluated during the re-examination. Comparison of the crack lengths measured in 2002 and 2007 revealed that crack growth had occurred in four of the nine previously measured cracks. The crack length extension ranged from 0.25 to 1.8 inches. However, in all cases the cracks still remained within the residual stress zone (i.e., within two to three inches of the weld). The impact of the cracks that grew on the future service of Tank 15 was re-assessed. API-579 crack instability calculations were again performed, based on expected future service conditions and trended crack growth rates for the future tank service cycle. The analysis showed that the combined hydrostatic and weld residual stresses do not drive the identified cracks to instability. This tank expected to be decommissioned in the near future. However, if these plans are delayed, it was recommended that a third examination of selected cracks in the tank be performed in 2014.

Wiersma, B; James Elder, J; Rodney Vandekamp, R; Charles Mckeel, C

2009-04-23T23:59:59.000Z

319

THE GREEN BANK TELESCOPE H II REGION DISCOVERY SURVEY. IV. HELIUM AND CARBON RECOMBINATION LINES  

SciTech Connect

The Green Bank Telescope H II Region Discovery Survey (GBT HRDS) found hundreds of previously unknown Galactic regions of massive star formation by detecting hydrogen radio recombination line (RRL) emission from candidate H II region targets. Since the HRDS nebulae lie at large distances from the Sun, they are located in previously unprobed zones of the Galactic disk. Here, we derive the properties of helium and carbon RRL emission from HRDS nebulae. Our target sample is the subset of the HRDS that has visible helium or carbon RRLs. This criterion gives a total of 84 velocity components (14% of the HRDS) with helium emission and 52 (9%) with carbon emission. For our highest quality sources, the average {sup 4}He{sup +}/H{sup +} abundance ratio by number, (y {sup +}), is 0.068 {+-} 0.023(1{sigma}). This is the same ratio as that measured for the sample of previously known Galactic H II regions. Nebulae without detected helium emission give robust y {sup +} upper limits. There are 5 RRL emission components with y {sup +} less than 0.04 and another 12 with upper limits below this value. These H II regions must have either a very low {sup 4}He abundance or contain a significant amount of neutral helium. The HRDS has 20 nebulae with carbon RRL emission but no helium emission at its sensitivity level. There is no correlation between the carbon RRL parameters and the 8 {mu}m mid-infrared morphology of these nebulae.

Wenger, Trey V.; Bania, T. M. [Astronomy Department, 725 Commonwealth Avenue, Boston University, Boston, MA 02215 (United States)] [Astronomy Department, 725 Commonwealth Avenue, Boston University, Boston, MA 02215 (United States); Balser, Dana S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903-2475 (United States)] [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903-2475 (United States); Anderson, L. D. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)] [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)

2013-02-10T23:59:59.000Z

320

Angle of crack propagation for a vertical hydraulic fracture  

DOE Green Energy (OSTI)

Using the strain-energy-density-factor (S) theory, the positive fracture angle +theta/sub o/ (the initial fracture angle of crack propagation) of a near-vertical crack is predicted by using the opening- and sliding-mode stress-intensity factors in the presence of the overburden pressure, the least in situ horizontal principal stress, and the borehole fluid pressure. The crack spreads in the positive theta/sub o/ direction (counter-clockwise) in the plane for which S is a minimum, S/sub min/. It was verified that S/sub min/ is greater than or equal to S/sub c/. The quantity S/sub c/ is defined as the critical value of S, and remains essentially constant. Of interest is the numerical example for calculating fracture angle and the critical uniform borehole fluid pressure required to initiate fracture at such an angle for the present LASL Dry Hot Rock Geothermal Energy Program. (auth)

Sarda, J.P.; Hsu, Y.C.

1975-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Characterization of geothermal reservoir crack patterns using shear-wave  

Open Energy Info (EERE)

geothermal reservoir crack patterns using shear-wave geothermal reservoir crack patterns using shear-wave splitting Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Characterization of geothermal reservoir crack patterns using shear-wave splitting Details Activities (1) Areas (1) Regions (0) Abstract: Microearthquakes recorded by a downhole, three-component seismic network deployed around the Coso, California, geothermal reservoir since 1992 display distinctive shear-wave splitting and clear polarization directions. From the polarizations the authors estimated three predominant subsurface fracture directions, and from the time delays of the split waves they determined tomographically the 3-D fracture density distribution in the reservoir. Author(s): Lou, M.; Rial, J.A. Published: Geophysics, 3/1/1997

322

Shear-wave splitting and reservoir crack characterization: the Coso  

Open Energy Info (EERE)

Shear-wave splitting and reservoir crack characterization: the Coso Shear-wave splitting and reservoir crack characterization: the Coso geothermal field Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Shear-wave splitting and reservoir crack characterization: the Coso geothermal field Details Activities (1) Areas (1) Regions (0) Abstract: This paper aims to improve current understanding of the subsurface fracture system in the Coso geothermal field, located in east-central California. The Coso reservoir is in active economic development, so that knowledge of the subsurface fracture system is of vital importance for an accurate evaluation of its geothermal potential and day-to-day production. To detect the geometry and density of fracture systems we applied the shear-wave splitting technique to a large number of

323

Cracking Condition of Cohesionless Porous Materials in Drying Processes  

E-Print Network (OSTI)

The invasion of air into porous systems in drying processes is often localized in soft materials, such as colloidal suspensions and granular pastes, and it typically develops in the form of cracks before ordinary drying begins. To investigate such processes, we construct an invasion percolation model on a deformable lattice for cohesionless elastic systems, and with this model we derive the condition under which cracking occurs. A Griffith-like condition characterized by a dimensionless parameter is proposed, and its validity is checked numerically. This condition indicates that the ease with which cracking occurs increases as the particles composing the material become smaller, as the rigidity of the system increases, and as the degree of heterogeneity characterizing the drying processes decreases.

So Kitsunezaki

2013-01-15T23:59:59.000Z

324

Stress corrosion cracking of candidate waste container materials  

SciTech Connect

Six alloys have been selected as candidate container materials for the storage of high-level nuclear waste at the proposed Yucca Mountain site in Nevada. These materials are Type 304L stainless steel (SS), Type 316L SS, Incology 825, P-deoxidized Cu, Cu-30%Ni, and Cu-7% Al. The present program has been initiated to determine whether any of these materials can survive for 300 years in the site environment without developing through-wall stress corrosion cracks, and to assess the relative resistance of these materials to stress corrosion cracking (SCC). A series of slow-strain-rate tests (SSRTs) in simulated Well J-13 water which is representative of the groundwater present at the Yucca Mountain site has been completed, and crack-growth-rate (CGR) tests are also being conducted under the same environmental conditions. 13 refs., 60 figs., 22 tabs.

Maiya, P.S.; Soppet, W.K.; Park, J.Y.; Kassner, T.F.; Shack, W.J.; Diercks, D.R.

1990-11-01T23:59:59.000Z

325

Cracking a Cold Case and Enduring Mystery | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Cracking a Cold Case and Enduring Mystery Cracking a Cold Case and Enduring Mystery Cracking a Cold Case and Enduring Mystery July 1, 2013 - 3:04pm Addthis Chris Brandon of the ROMACONS project collects a sample of ancient Roman concrete drilled from a breakwater in Pozzuoli Bay, near Naples, Italy. The breakwater dates back to roughly 37 B.C. | Photo courtesy of J.P. Oleson. Chris Brandon of the ROMACONS project collects a sample of ancient Roman concrete drilled from a breakwater in Pozzuoli Bay, near Naples, Italy. The breakwater dates back to roughly 37 B.C. | Photo courtesy of J.P. Oleson. Charles Rousseaux Charles Rousseaux Senior Writer, Office of Science What are the key facts? Modern concrete buildings -- most made with Portland cement -- are built to last for a hundred or so years. But Roman concrete has withstood

326

Conditions For Successful Helium Detonations In Astrophysical Environments  

E-Print Network (OSTI)

Several models for type Ia-like supernovae events rely on the production of a self-sustained detonation powered by nuclear reactions.In the absence of hydrogen, the fuel that powers these detonations typically consists of either pure helium (He) or a mixture of carbon and oxygen (C/O). Studies that systematically determine the conditions required to initiate detonations in C/O material exist, but until now no analogous investigation of degenerate He matter has been conducted. We perform one-dimensional reactive hydrodynamical simulations at a variety of initial density and temperature combinations and find critical length scales for the initiation of He detonations that range between 1 -- $10^{10}$ cm. These sizes are consistently smaller than the corresponding Chapman-Jouguet (CJ) length scales by a factor of ~100, providing opportunities for thermonuclear explosions in a wider range of low mass white dwarfs (WDs) than previously thought possible. We find that virialized WDs with as little mass as 0.24 $M_\\o...

Holcomb, Cole; De Colle, Fabio; Ramirez-Ruiz, Enrico

2013-01-01T23:59:59.000Z

327

Once-ionized helium in superstrong magnetic fields  

E-Print Network (OSTI)

It is generally believed that magnetic fields of some neutron stars, the so-called magnetars, are enormously strong, up to 10^{14} - 10^{15} G. Recent investigations have shown that the atmospheres of magnetars are possibly composed of helium. We calculate the structure and bound-bound radiative transitions of the He^+ ion in superstrong fields, including the effects caused by the coupling of the ion's internal degrees of freedom to its center-of-mass motion. We show that He^+ in superstrong magnetic fields can produce spectral lines with energies of up to about 3 keV, and it may be responsible for absorption features detected recently in the soft X-ray spectra of several radio-quiet isolated neutron stars. Quantization of the ion's motion across a magnetic field results in a fine structure of spectral lines, with a typical spacing of tens electron-volts in magnetar-scale fields. It also gives rise to ion cyclotron transitions, whose energies and oscillator strengths depend on the state of the bound ion.

George G. Pavlov; Victor G. Bezchastnov

2005-05-23T23:59:59.000Z

328

USE OF THE MODULAR HELIUM REACTOR FOR HYDROGEN PRODUCTION  

DOE Green Energy (OSTI)

OAK-B135 A significant ''Hydrogen Economy'' is predicted that will reduce our dependence on petroleum imports and reduce pollution and greenhouse gas emissions. Hydrogen is an environmentally attractive fuel that has the potential to displace fossil fuels, but contemporary hydrogen production is primarily based on fossil fuels. The author has recently completed a three-year project for the US Department of Energy (DOE) whose objective was to ''define an economically feasible concept for production of hydrogen, using an advanced high-temperature nuclear reactor as the energy source''. Thermochemical water-slitting, a chemical process that accomplishes the decomposition of water into hydrogen and oxygen, met this objective. The goal of the first phase of this study was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen, and to select one for further detailed consideration. They selected the Sulfur-Iodine cycle. In the second phase, they reviewed all the basic reactor types for suitability to provide the high temperature heat needed by the selected thermochemical water splitting cycle and chose the helium gas-cooled reactor. In the third phase they designed the chemical flowsheet for the thermochemical process and estimated the efficiency and cost of the process and the projected cost of producing hydrogen. These results are summarized in this report.

SCHULTZ,KR

2003-09-01T23:59:59.000Z

329

Helium Behavior in Oxide Nuclear Fuels: First Principles Modeling  

Science Conference Proceedings (OSTI)

UO2 and (U, Pu)O2 solid solutions (the so-called MOX) nowadays are used as commercial nuclear fuels in many countries. One of the safety issues during the storage of these fuels is related to their self-irradiation that produces and accumulates point defects and helium therein. We present density functional theory (DFT) calculations for UO2, PuO2 and MOX containing He atoms in octahedral interstitial positions. In particular, we calculated basic MOX properties and He incorporation energies as functions of Pu concentration within the spin-polarized, generalized gradient approximation (GGA) DFT calculations. We also included the on-site electron correlation corrections using the Hubbard model (in the framework of the so-called DFT + U approach). We found that PuO2 remains semiconducting with He in the octahedral position while UO2 requires a specific lattice distortion. Both materials reveal a positive energy for He incorporation, which, therefore, is an exothermic process. The He incorporation energy increases with the Pu concentration in the MOX fuel.

Gryaznov, D.; Rashkeev, Sergey N.; Kotomin, E. A.; Heifets, Eugene; Zhukovskii, Yuri F.

2010-10-01T23:59:59.000Z

330

Dynamic crack initiation toughness : experiments and peridynamic modeling.  

SciTech Connect

This is a dissertation on research conducted studying the dynamic crack initiation toughness of a 4340 steel. Researchers have been conducting experimental testing of dynamic crack initiation toughness, K{sub Ic}, for many years, using many experimental techniques with vastly different trends in the results when reporting K{sub Ic} as a function of loading rate. The dissertation describes a novel experimental technique for measuring K{sub Ic} in metals using the Kolsky bar. The method borrows from improvements made in recent years in traditional Kolsky bar testing by using pulse shaping techniques to ensure a constant loading rate applied to the sample before crack initiation. Dynamic crack initiation measurements were reported on a 4340 steel at two different loading rates. The steel was shown to exhibit a rate dependence, with the recorded values of K{sub Ic} being much higher at the higher loading rate. Using the knowledge of this rate dependence as a motivation in attempting to model the fracture events, a viscoplastic constitutive model was implemented into a peridynamic computational mechanics code. Peridynamics is a newly developed theory in solid mechanics that replaces the classical partial differential equations of motion with integral-differential equations which do not require the existence of spatial derivatives in the displacement field. This allows for the straightforward modeling of unguided crack initiation and growth. To date, peridynamic implementations have used severely restricted constitutive models. This research represents the first implementation of a complex material model and its validation. After showing results comparing deformations to experimental Taylor anvil impact for the viscoplastic material model, a novel failure criterion is introduced to model the dynamic crack initiation toughness experiments. The failure model is based on an energy criterion and uses the K{sub Ic} values recorded experimentally as an input. The failure model is then validated against one class of problems showing good agreement with experimental results.

Foster, John T.

2009-10-01T23:59:59.000Z

331

Weld solidification cracking in 304 to 204L stainless steel  

Science Conference Proceedings (OSTI)

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.

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

332

Weld solidification cracking in 304 to 304L stainless steel  

Science Conference Proceedings (OSTI)

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.

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

333

Relative Humidity and the Susceptibility of Austenitic Stainless Steel to Stress Corrosion Cracking in an impure Plutonium Oxide Environment  

SciTech Connect

Laboratory tests to investigate the corrosivity of moist plutonium oxide/chloride salt mixtures on 304L and 316L stainless steel coupons showed that corrosion occurred in selected samples. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The exposures were conducted in sealed containers in which the oxide-salt mixtures were loaded with about 0.6 wt % water from a humidified helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration, the composition of the salt and the moisture present in the test environment. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride and 0.6 wt% water. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl{sub 2}. The cracking was associated with the heat-affected zone of an autogenous weld that ran across the center of the coupon. Cracking was not observed in coupons exposed to the headspace gas above the solid mixture, or in coupons exposed to other mixtures with either no CaCl{sub 2} or 0.92 wt% CaCl{sub 2}. SCC was present where the 0.6 wt % water content exceeded the value needed to fully hydrate the available CaCl{sub 2}, but was absent where the water content was insufficient. These results reveal the significance of the relative humidity in the austenitic stainless steels environment to their susceptibility to corrosion. The relative humidity in the test environment was controlled by the water loading and the concentration of the hydrating salts such as CaCl{sub 2}. For each salt or salt mixture there is a threshold relative humidity below which the necessary liquid electrolyte cannot exist, and therefore below which the SCC risk is very low. This threshold is a thermodynamic quantity known as the deliquescence relative humidity that is dependent on the identity of the salt but is independent of the quantity of salt. Below the deliquescence RH there should be low corrosion risk, and above it the corrosion risk increases rapidly as a liquid phase, which is initially saturated with salt, grows and becomes more widespread in the container.

Zapp, P.; Duffey, J.; Lam, P.; Dunn, K.

2010-05-05T23:59:59.000Z

334

FITNESS-FOR-SERVICE ASSESSMENT FOR A RADIOACTIVE WASTE TANK THAT CONTAINS STRESS CORROSION CRACKS  

Science Conference Proceedings (OSTI)

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The tanks are examined by ultrasonic (UT) methods for thinning, pitting, and stress corrosion cracking in order to assess fitness-for-service. During an inspection in 2002, ten cracks were identified on one of the tanks. Given the location of the cracks (i.e., adjacent to welds, weld attachments, and weld repairs), fabrication details (e.g., this tank was not stress-relieved), and the service history the degradation mechanism was stress corrosion cracking. Crack instability calculations utilizing API-579 guidance were performed to show that the combination of expected future service condition hydrostatic and weld residual stresses do not drive any of the identified cracks to instability. The cracks were re-inspected in 2007 to determine if crack growth had occurred. During this re-examination, one indication that was initially reported as a 'possible perpendicular crack API-579 crack instability calculations were again performed, based on expected future service conditions and trended crack growth rates for the future tank service cycle. The analysis showed that the combined hydrostatic and weld residual stresses do not drive the identified cracks to instability. This tank expected to be decommissioned in the near future. However, if these plans are delayed, it was recommended that a third examination of selected cracks in the tank be performed in 2014.

Wiersma, B; James Elder, J; Rodney Vandekamp, R; Charles Mckeel, C

2009-04-23T23:59:59.000Z

335

Hydrogen sulfide stress corrosion cracking in materials for geothermal power  

DOE Green Energy (OSTI)

Studies to evaluate the performance of alloys used in geothermal power systems are reported. Alloys which are commercially available and those which have modified metallurgical structures and/or composition modifications were tested to determine the corrosive effects of the H/sub 2/S and thermal environments in geothermal fluids. Hydrogen embrittlement and sulfide stress corrosion cracking were tested. Test results showing the effects of alloy composition, tempering temperatures, fluid temperature and salt content, and ageing on sulfide stress cracking are tabulated. (LCL)

Hehemann, R.F.; Troiano, A.R.; Abu-Khater, B.; Ferrigno, S.

1976-01-01T23:59:59.000Z

336

Hartree-Fock calculations for the photoionisation of helium and helium-like ions in neutron star magnetic fields  

E-Print Network (OSTI)

We derive the photoionisation cross section in dipole approximation for many-electron atoms and ions for neutron star magnetic field strengths in the range of 10^7 to 10^9 T. Both bound and continuum states are treated in adiabatic approximation in a self-consistent way. Bound states are calculated by solving the Hartree-Fock-Roothaan equations using finite-element and B-spline techniques while the continuum orbital is calculated by direct integration of the Hartree-Fock equations in the mean-field potential of the remaining bound orbitals. We take into account mass and photon density in the neutron star's atmosphere as well as thermal occupation of the levels. The data are of importance for the quantitative interpretation of observed x-ray spectra that originate from the thermal emission of isolated neutron stars. They can serve as input for modeling neutron star atmospheres as regards chemical composition, magnetic field strength, temperature, and redshift. Our main focus in this paper lies on helium, heliu...

Kersting, Thorsten; Diemand, Peter; Wunner, Günter

2013-01-01T23:59:59.000Z

337

Thermal stress cracking and enhancement of heat extraction from fractured geothermal reservoirs  

DOE Green Energy (OSTI)

The effects of thermal stress cracking, upon heat extraction were studied. Very fundamental approximate analyses were performed to elucidate the mechanics of thermal stress cracking, and the main results are summarized.

Murphy, H.D.

1978-01-01T23:59:59.000Z

338

Crack Growth in Solid Oxide Fuel Cell Materials: From Discrete to Continuum Damage Modeling  

Science Conference Proceedings (OSTI)

This paper addresses the cracking problem of glass and ceramic materials used in solid oxide fuel cells (SOFCs). Analyses of an internal crack and of an interface crack between dissimilar materials were conducted using a modified boundary layer modeling approach. In this approach, fracture is allowed to occur in a small process window situated at an initial crack tip. Elastic displacement crack-tip fields are prescribed as remote boundary conditions. Crack propagation was first modeled discretely. Next, a continuum damage mechanics (CDM) model for brittle materials was developed to capture damage and crack growth in the process window. In particular, the damage model was applied to a glass-ceramic material that had been developed in-house for sealing purposes. Discrete and continuum damage solutions were then compared. Finally, the CDM model was used to determine the crack propagation direction as a function of a mode mixity measure.

Nguyen, Ba Nghiep; Koeppel, Brian J.; Ahzi, Said; Khaleel, Mohammad A.; Singh, Prabhakar

2006-04-01T23:59:59.000Z

339

Laboratory And Field Investigations To Address Erosion, Volume Change And Desiccation Cracking Of Compost Amended Expansive Subsoils.  

E-Print Network (OSTI)

??Puppala, Anand Desiccations cracks are formed during drying process of fine grained cohesive soils in summer and these cracks often appear on unpaved subgrades due… (more)

Intharasombat, Napat

2007-01-01T23:59:59.000Z

340

Status Report on Studies of Recovery Boiler Composite Floor Tube Cracking  

DOE Green Energy (OSTI)

likelihood of cracking. This report is the latest in a series of progress reports presented on this project.

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

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Influence of p-method finite element parameters on predictions of crack front geometry  

Science Conference Proceedings (OSTI)

The effect of various p-method finite element model parameters on the prediction of planar crack front geometry in three dimensional structures is evaluated. An automatic crack growth method was developed using the commercial software StressCheck coupled ... Keywords: ?, Corner crack, Crack front, Finite element, Mesh, Stress intensity factor, a, b, b/a, c, ctrat, ipr, m, mrat, p-method, trans

Diane Wowk, Kyle Gamble, Ross Underhill

2013-10-01T23:59:59.000Z

342

Effect of Specimen Size on the Crack Growth Rate Behavior of Irradiated Type 304 Stainless Steel  

Science Conference Proceedings (OSTI)

BackgroundCracks in actual plant components are mainly under plane strain. In order to generate relevant crack growth rate data in the laboratory, specimens where most of the crack front is under plane strain should be used. Since the ASTM E399 size criterion for linear elastic plane-strain fracture toughness is probably conservative, it seems appropriate to also apply it to SCC tests. However, in stress corrosion crack growth rate (CGR) tests on austenitic stainless ...

2012-12-21T23:59:59.000Z

343

Influences of gaseous environment on low growth-rate fatigue crack propagation in steels. Annual report No. 1, January 1980. Report No. FPL/R/80/1030  

DOE Green Energy (OSTI)

The influence of gaseous environment is examined on fatigue crack propagation behavior in steels. Specifically, a fully martensitic 300-M ultrahigh strength steel and a fully bainitic 2-1/4Cr-1Mo lower strength steel are investigated in environments of ambient temperature moist air and low pressure dehumidified hydrogen and argon gases over a wide range of growth rates from 10/sup -8/ to 10/sup -2/ mm/cycle, with particular emphasis given to behavior near the crack propagation threshold ..delta..K/sub 0/. It is found that two distinct growth rate regimes exist where hydrogen can markedly accelerate crack propagation rates compared to air, (1) at near-threshold levels below (5 x 10/sup -6/ mm/cycle) and (2) at higher growth rates, typically around 10/sup -5/ mm/cycle above a critical maximum stress intensity K/sub max//sup T/. Hydrogen-assisted crack propagation at higher growth rates is attributed to a hydrogen embrittlement mechanism, with K/sub max//sup T/ nominally equal to K/sub Iscc/ (the sustained load stress corrosion threshold) in high strength steels, and far below K/sub Iscc/ in the strain-rate sensitive lower strength steels. Hydrogen-assisted crack propagation at near-threshold levels is attributed to a new mechanism involving fretting-oxide-induced crack closure generated in moist (or oxygenated) environments. The absence of hydrogen embrittlement mechanisms at near-threshold levels is supported by tests showing that ..delta..K/sub 0/ values in dry gaseous argon are similar to ..delta..K/sub 0/ values in hydrogen. The potential ramifications of these results are examined in detail.

Ritchie, R.O.; Suresh, S.; Toplosky, J.

1980-01-01T23:59:59.000Z

344

D0 Silicon Upgrade: Commissioning Test Results for D-Zero's Helium Refrigerator  

Science Conference Proceedings (OSTI)

The test objectives are: (1) Make liquid helium and measure refrigerator capacity; (2) Measure liquid helium dewar heat leak, transfer line heat leak, and liquid nitrogen consumption rates; (3) Operate all cryogenic transfer lines; (4) Get some running time on all components; (5) Debug mechanical components, instrumentation, DMACs user interface, tune loops, and otherwise shake out any problems; (6) Get some operating time in to get familiar with system behavior; (7) Revise and/or improve operating procedures to actual practice; and (8) Identify areas for future improvement. D-Zero's stand alone helium refrigerator (STAR) liquified helium at a rate of 114 L/hr. This is consistent with other STAR installations. Refrigeration capacity was not measured due to lack of a calibrated heat load. Measured heat leaks were within design values. The helium dewar loss was measured at 2 to 4 watts or 9% per day, the solenoid and VLPC helium transfer lines had a heat leak of about 20 watts each. The liquid nitrogen consumption rates of the mobile purifier, STAR, and LN2 subcooler were measured at 20 gph, 20 to 64 gph, and 3 gph respectively. All cryogenic transfer lines including the solenoid and visible light photon counter (VLPC) transfer lines were cooled to their cryogenic operating temperatures. This included independent cooling of nitrogen shields and liquid helium components. No major problems were observed. The system ran quite well. Many problems were identified and corrected as they came up. Areas for improvement were noted and will be implemented in the future. The instrumentation and control system operated commendably during the test. The commissioning test run was a worthwhile and successful venture.

Rucinski, Russ; /Fermilab

1997-06-30T23:59:59.000Z

345

ALTERNATIVES TO HELIUM-3 FOR NEUTRON MULTIPLICITY DETECTORS  

Science Conference Proceedings (OSTI)

Collaboration between the Pacific Northwest National Laboratory (PNNL) and the Los Alamos National Laboratory (LANL) is underway to evaluate neutron detection technologies that might replace the high-pressure helium (3He) tubes currently used in neutron multiplicity counter for safeguards applications. The current stockpile of 3He is diminishing and alternatives are needed for a variety of neutron detection applications including multiplicity counters. The first phase of this investigation uses a series of Monte Carlo calculations to simulate the performance of an existing neutron multiplicity counter configuration by replacing the 3He tubes in a model for that counter with candidate alternative technologies. These alternative technologies are initially placed in approximately the same configuration as the 3He tubes to establish a reference level of performance against the 3He-based system. After these reference-level results are established, the configurations of the alternative models will be further modified for performance optimization. The 3He model for these simulations is the one used by LANL to develop and benchmark the Epithermal Neutron Multiplicity Counter (ENMC) detector, as documented by H.O. Menlove, et al. in the 2004 LANL report LA-14088. The alternative technologies being evaluated are the boron-tri-fluoride-filled proportional tubes, boron-lined tubes, and lithium coated materials previously tested as possible replacements in portal monitor screening applications, as documented by R.T. Kouzes, et al. in the 2010 PNNL report PNNL-72544 and NIM A 623 (2010) 1035–1045. The models and methods used for these comparative calculations will be described and preliminary results shown

Ely, James H.; Siciliano, Edward R.; Swinhoe, Martyn T.

2012-02-07T23:59:59.000Z

346

Helium-cooled molten-salt fusion breeder  

Science Conference Proceedings (OSTI)

We present a new conceptual design for a fusion reactor blanket that is intended to produce fissile material for fission power plants. Fast fission is suppressed by using beryllium instead of uranium to multiply neutrons. Thermal fission is suppressed by minimizing the fissile inventory. The molten-salt breeding medium (LiF + BeF/sub 2/ + ThF/sub 4/) is circulated through the blanket and to the on-line processing system where /sup 233/U and tritium are continuously removed. Helium cools the blanket and the austenitic steel tubes that contain the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion by molten salt. We estimate that a breeder having 3000 MW of fusion power will produce 6500 kg of /sup 233/U per year. This amount is enough to provide makeup for 20 GWe of light-water reactors per year or twice that many high-temperature gas-cooled reactors or Canadian heavy-water reactors. Safety is enhanced because the afterheat is low and blanket materials do not react with air or water. The fusion breeder based on a pre-MARS tandem mirror is estimated to cost $4.9B or 2.35 times a light-water reactor of the same power. The estimated cost of the /sup 233/U produced is $40/g for fusion plants costing 2.35 times that of a light-water reactor if utility owned or $16/g if government owned.

Moir, R.W.; Lee, J.D.; Fulton, F.J.; Huegel, F.; Neef, W.S. Jr.; Sherwood, A.E.; Berwald, D.H.; Whitley, R.H.; Wong, C.P.C.; Devan, J.H.

1984-12-01T23:59:59.000Z

347

Hydrogen and helium traces in type Ib-c supernovae  

E-Print Network (OSTI)

The spectroscopic properties of a selected optical photospheric spectra of core collapse supernovae (CCSNe) are investigated.Special attention is devoted to traces of hydrogen at early phases. The generated spectra are found to match the observed ones reasonably well, including a list of only 23 candidate ions. Guided by SN Ib 1990I, the observed trough near 6300\\AA is attributed to H$\\alpha$ in almost all Type Ib events, although in some objects it becomes too weak to be discernible, especially at later phases. Alternative line identifications are discussed. Differences in the way hydrogen manifests its presence within CCSNe are highlighted. In Type Ib SNe, the H$\\alpha$ contrast velocity (i.e. line velocity minus the photospheric velocity) seems to increase with time at early epochs, reaching values as high as 8000 km s$^{-1}$ around 15-20 days after maximum and then remains almost constant. The derived photospheric velocities, indicate a lower velocity for Type II SNe 1987A and 1999em as compared to SN Ic 1994I and SN IIb 1993J, while Type Ib events display a somewhat larger variation. The scatter, around day 20, is measured to be $\\sim$5000 km s$^{-1}$. Following two simple approaches, rough estimates of ejecta and hydrogen masses are given. A mass of hydrogen of approximately 0.02 $M_\\odot$ is obtained for SN 1990I, while SNe 1983N and 2000H ejected $\\sim$0.008 $M_\\odot$ and $\\sim$0.08 $M_\\odot$ of hydrogen, respectively. SN 1993J has a higher hydrogen mass, $\\sim 0.7$ $M_\\odot$ with a large uncertainty. A low mass and thin hydrogen layer with very high ejection velocities above the helium shell, is thus the most likely scenario for Type Ib SNe. Some interesting and curious issues relating to oxygen lines suggest future investigations.

A. Elmhamdi; I. J. Danziger; D. Branch; B. Leibundgut; E. Baron; R. P. Kirshner

2005-12-22T23:59:59.000Z

348

A computational study of the time dependent crack growth process  

SciTech Connect

Universal studies of creep crack growth for (1) constant load and (2) variable load cases are presented. Results of the constant load cases is compared to experiment. The behavior of displacements and integral creep for fracture parameters are discussed for both load cases. The need for using a constitutive law which can handle cyclic creep is discussed.

Brust, F.W.; Krishnaswamy, P.

1992-01-01T23:59:59.000Z

349

Ductile Fracture Handbook, Volume 1: Circumferential Throughwall Cracks  

Science Conference Proceedings (OSTI)

Over the past 10 years, the focus of fracture research related to nuclear power plants has shifted from brittle fractures to fractures of steels used for piping and vessels. This handbook developed by EPRI and Novetech Corporation is the first single-source document containing formulas for evaluating throughwall cracks in these tough ductile steels.

1989-07-01T23:59:59.000Z

350

Method of making crack-free zirconium hydride  

DOE Patents (OSTI)

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.

Sullivan, Richard W. (Denver, CO)

1980-01-01T23:59:59.000Z

351

Fatigue crack growth estimation by relevance vector machine  

Science Conference Proceedings (OSTI)

The investigation of damage propagation mechanisms on a selected safety-critical component or structure requires the quantification of its remaining useful life (RUL) to verify until when it can continue performing the required function. In this work, ... Keywords: Bayesian techniques, Fatigue crack growth, Prognostics, Relevance vector machine, Residual useful life, Support vector machine

Enrico Zio; Francesco Di Maio

2012-09-01T23:59:59.000Z

352

Solvent control of crack dynamics in a reversible hydrogel  

E-Print Network (OSTI)

The resistance to fracture of reversible biopolymer hydrogels is an important control factor of the cutting/slicing and eating characteristics of food gels. It is also critical for their utilization in tissue engineering, for which mechanical protection of encapsulated components is needed. Its dependence on loading rate and, recently, on the density and strength of cross-links has been investigated. But no attention was paid so far to solvent nor to environment effects. Here we report a systematic study of crack dynamics in gels of gelatin in water/glycerol mixtures. We show on this model system that: (i) increasing solvent viscosity slows down cracks; (ii) soaking with solvent increases markedly gel fragility; (iii) tuning the viscosity of the (miscible) environmental liquid affects crack propagation via diffusive invasion of the crack tip vicinity. The results point toward the fact that fracture occurs by viscoplastic chain pull-out. This mechanism, as well as the related phenomenology, should be common to all reversibly cross-linked (physical) gels.

Tristan Baumberger; Christiane Caroli; David Martina

2006-05-16T23:59:59.000Z

353

Catalytic cracking. (Latest citations from the Compendex database). Published Search  

Science Conference Proceedings (OSTI)

The bibliography contains citations concerning applications of catalytic cracking processes in fluidized bed systems, moving beds, refineries, vacuum distillations, and reformers. Design aspects, modeling, control systems, and operating procedures are also discussed. (Contains a minimum of 149 citations and includes a subject term index and title list.)

Not Available

1993-07-01T23:59:59.000Z

354

Incipient Crack Detection in Composite Wind Turbine Blades  

DOE Green Energy (OSTI)

This paper presents some analysis results for incipient crack detection in a 9-meter CX-100 wind turbine blade that underwent fatigue loading to failure. The blade was manufactured to standard specifications, and it underwent harmonic excitation at its first resonance using a hydraulically-actuated excitation system until reaching catastrophic failure. This work investigates the ability of an ultrasonic guided wave approach to detect incipient damage prior to the surfacing of a visible, catastrophic crack. The blade was instrumented with piezoelectric transducers, which were used in an active, pitchcatch mode with guided waves over a range of excitation frequencies. The performance results in detecting incipient crack formation in the fiberglass skin of the blade is assessed over the range of frequencies in order to determine the point at which the incipient crack became detectable. Higher excitation frequencies provide consistent results for paths along the rotor blade's carbon fiber spar cap, but performance falls off with increasing excitation frequencies for paths off of the spar cap. Lower excitation frequencies provide more consistent performance across all sensor paths.

Taylor, Stuart G. [Los Alamos National Laboratory; Choi, Mijin [Chonbuk National University, Korea; Jeong, Hyomi [Chonbuk National University, Korea; Jang, Jae Kyeong [Chonbuk National University, Korea; Park, Gyuhae [Chonnam National University, Korea; Farinholt, Kevin [Commonwealth Center for Advanced Manufacturing, VA; Farrar, Charles R. [Los Alamos National Laboratory; Ammerman, Curtt N. [Los Alamos National Laboratory; Todd, Michael D. [Los Alamos National Laboratory; Lee, Jung-Ryul [Chonbuk National University, Korea

2012-08-28T23:59:59.000Z

355

Early Development Of Stress Corrosion Cracks At The Grain Scale: Incomplete Random Tessellation Model  

E-Print Network (OSTI)

Early Development Of Stress Corrosion Cracks At The Grain Scale: Incomplete Random Tessellation is needed to quantify those effects more accurately. 1 INTRODUCTION Intergranular stress corrosion cracking to the dependence of microscopic stress fields at crack tips on the random orientation of neighboring grains

Cizelj, Leon

356

Age-based preventive maintenance for passive components submitted to stress corrosion cracking  

Science Conference Proceedings (OSTI)

This paper deals with an age-based preventive maintenance for critical systems or structures subject to a gradual degradation phenomenon such as stress corrosion cracking. We analyze a system subjected to different cracks. A crack can be only detected ... Keywords: Age-based maintenance, Counting processes, Gamma process, Non-homogeneous Poisson process, SCC models

I. T. Castro; Anne Barros; Antoine Grall

2011-07-01T23:59:59.000Z

357

Permeability and elastic properties of cracked glass under pressure A. OugierSimonin,1  

E-Print Network (OSTI)

on slow crack growth and stress corrosion processes [Wiederhorn, 1966; Anderson and Grew, 1977; Atkinson for independent controls of the confining pressure, the axial stress, and pore pressure. We produced cracks, to our knowledge, none con- sidered crack evolution under compressive stress. Some of this work explored

Fortin, Jérôme

358

How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks  

SciTech Connect

Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (<600 mu m) cracks propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses generally quoted for bone.

Ritchie, Robert O; Koester, K. J.; Ager III, J. W.; Ritchie, R.O.

2008-05-10T23:59:59.000Z

359

Uplift Pressures in Cracks in Concrete Gravity Dams--An Experimental Study: Volume 8  

Science Conference Proceedings (OSTI)

Uplift pressure distribution in cracks in concrete dams is affected by a combination of several factors, such as crack properties, drain dimensions, and the type of flow in the crack. This study shows that most uplift pressure distributions can be controlled using a vertical drain system with diameters from two to four inches and spacing of about ten feet.

1992-12-20T23:59:59.000Z

360

Detecting and Imaging He2 Molecules in Superfluid Helium by Laser-Induced Fluorescence  

E-Print Network (OSTI)

Dissertation Director: Professor Daniel N. McKinsey September 2008 #12;Copyright c 2008 by Wade G. Rellergert

McKinsey, Daniel

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Spallation-Fission Competition in Heaviest Elements; Helium Ion Induced Reactions in Plutonium Isotopes  

E-Print Network (OSTI)

Nuclear Energy Series, Plutonium Project Record, Vol. 1 4Nuclear Energy S e r i e s , Plutonium P r o j e c t RecordNuclear Energy S e r i e s , Plutonium P r o j e c t Record,

Glass, Richard A.; Carr, Robert J.; Cobble, James W.; Seaborg, Glenn T.

1956-01-01T23:59:59.000Z

362

Analysis of crack propagation and arrest in welded LNG (liquefied natural gas) storage tanks. Final report, March 1984-October 1986  

Science Conference Proceedings (OSTI)

The extensive safe-operating experience that has been accumulated in LNG storage tanks is strongly indicative of a high degree of structural integrity. Nevertheless, concern has arisen with regard to the presence of weld-induced fabrication flaws in these tanks. When such flaws exist, it may not be possible to preclude the initiation of unstable crack growth during operation. However, if it can be shown that the material has the ability to arrest a running crack, an adequate margin of safety can still be demonstrated. A comprehensive program of experimentation was undertaken in companion programs to develop the crack-arrest properties that are needed for such a demonstration. But, because the 9% nickel steel used for LNG tank materials is very ductile and tough, its fracture properties are not well characterized by the quasi-static linear elastic-fracture-mechanics techniques available to these researchers. The research was therefore aimed at assisting the experimental work by providing more-realistic dynamic and nonlinear fracture-mechanics analyses. These analyses were intended to enhance the experimental program and to help insure that the results of the research are appropriate for the assessment of LNG storage-tank integrity. Specifically, the application of these advanced analysis techniques has demonstrated the mildly anticonservative nature of conventional fracture-mechanics treatments for the materials and structural geometry of interest. Nevertheless, provided a defected region in a storage tank is not overly large, the tank materials examined in this research possess high-enough-crack arrest toughness values to preclude complete tank rupture.

Kanninen, M.F.; Dexter, R.J.; Polch, E.Z.; Popelar, C.H.

1986-12-31T23:59:59.000Z

363

EFFECTS OF CHEMISTRY AND OTHER VARIABLES ON CORROSION AND STRESS CORROSION CRACKING IN HANFORD DOUBLE SHELL TANKS  

SciTech Connect

Laboratory testing was performed to develop a comprehensive understanding of the corrosivity of the tank wastes stored in Double-Shell Tanks using simulants primarily from Tanks 241-AP-105, 241-SY-103 and 241-AW-105. Additional tests were conducted using simulants of the waste stored in 241-AZ-102, 241-SY-101, 241-AN-107, and 241-AY-101. This test program placed particular emphasis on defining the range of tank waste chemistries that do not induce the onset of localized forms of corrosion, particularly pitting and stress corrosion cracking. This document summarizes the key findings of the research program.

BROWN MH

2008-11-13T23:59:59.000Z

364

Estimation of tritium and helium inventory in the tritium handling system in Korea  

Science Conference Proceedings (OSTI)

In Korea, the Wolsong Tritium Removal Facility (WTRF) is under construction to reduce the amount of tritium present in the moderator and coolant of the CANDU type Wolsong nuclear power plants. Recently, a study on the tritium handling system for recovery of the tritium collected from the WTRF was started. Some tritium would enter the steel of the container walls and subsequently decay to helium. This helium can deteriorate the mechanical properties of the material of the tritium handling system. To evaluate the tritium and helium inventory in the stainless steel wall of this system, the time-dependent diffusion equation was developed, solved and the results are presented in this paper. These results were compared to previous work that evaluated the tritium inventory in the stainless steel wall of 50-L tritium containers. Tritium and helium concentration profiles and the corresponding inventories were evaluated with respect to the various parameters such as exposure time, temperature, and partial pressure. After 24 years, the helium inventory in the wall of the tritium handling system exceeds the tritium inventory. (authors)

Yook, D.; Lee, S.; Lee, K. [Dept. of Nuclear Eng., KAIST, 373-1, Kusong-dong, Yusong-gu, Daejon 305-701 (Korea, Republic of); Song, K. M.; Shon, S. H. [KEPRI, 103-16 Munji-Dong, Yuseong-Gu, Daejeon, 305-380 (Korea, Republic of)

2008-07-15T23:59:59.000Z

365

HELIUM SHELL DETONATIONS ON LOW-MASS WHITE DWARFS AS A POSSIBLE EXPLANATION FOR SN 2005E  

SciTech Connect

Recently, several Type Ib supernovae (SNe; with the prototypical SN 2005E) have been shown to have atypical properties. These SNe are faint (absolute peak magnitude of {approx} - 15) and fast SNe that show unique composition. They are inferred to have low ejecta mass (a few tenths of a solar mass) and to be highly enriched in calcium, but poor in silicon elements and nickel. These SNe were therefore suggested to belong to a new class of calcium-rich faint SNe explosions. Their properties were proposed to be the result of helium detonations that may occur on helium accreting white dwarfs. In this paper, we theoretically study the scenario of helium detonations and focus on the results of detonations in accreted helium layers on low-mass carbon-oxygen (CO) cores. We present new results from one-dimensional simulations of such explosions, including their light curves and spectra. We find that when the density of the helium layer is low enough the helium detonation produces large amounts of intermediate elements, such as calcium and titanium, together with a large amount of unburnt helium. Alternatively, enough carbon enrichment of the accreted helium as a result of convective undershoot at the early stages of the runaway can avoid the production of iron group elements as the alpha particles are consumed avoiding iron production. Our results suggest that the properties of calcium-rich faint SNe could indeed be consistent with the helium-detonation scenario on small CO cores. Above a certain density (larger CO cores) the detonation leaves mainly {sup 56}Ni and unburnt helium, and the predicted spectrum will unlikely fit the unique features of this class of SNe. Finally, none of our studied models reproduces the bright, fast-evolving light curves of another type of peculiar SNe suggested to originate in helium detonations (SNe 1885A, 1939B, and 2002bj).

Waldman, Roni; Livne, Eli; Glasner, Ami [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Sauer, Daniel [Stockholm University, Department for Astronomy, AlbaNova University Center, 106 91 Stockholm (Sweden); Perets, Hagai [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mazzali, Paolo [Max-Planck Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching (Germany); Truran, James W. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Gal-Yam, Avishay [Benoziyo Center for Astrophysics, Faculty of Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

2011-09-01T23:59:59.000Z

366

How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks  

Science Conference Proceedings (OSTI)

Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses generally quoted for bone.

Ritchie, Robert O; Koester, K. J.; Ager III, J. W.; Ritchie, R.O.

2008-05-10T23:59:59.000Z

367

Cooling Strings of Superconducting Devices below 2 K the Helium II Bayonet Heat Exchanger  

E-Print Network (OSTI)

High-energy particle accelerators and colliders contain long strings of superconducting devices - acceleration RF cavities and magnets - operating at high field, which may require cooling in helium II below 2 K. In order to maintain adequate operating conditions, the applied or generated heat loads must be extracted and transported with minimum temperature difference. Conventional cooling schemes based on conductive or convective heat transport in pressurized helium II very soon reach their intrinsic limits of thermal impedance over extended lengths. We present the concept of helium II bayonet heat exchanger, which has been developed at CERN for the magnet cooling scheme of the Large Hadron Collider (LHC), and describe its specific advantages as a slim, quasi-isothermal heat sink. Experimental results obtained on several test set-ups, and a prototype magnet string have permitted to validate its performance and sizing rules, for transporting linear heat loads in the W.m-1 range over distances of several tens o...

Lebrun, P; Tavian, L; Van Weelderen, R

1998-01-01T23:59:59.000Z

368

Flow Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope  

Open Energy Info (EERE)

Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope Trends Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Flow Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope Trends Details Activities (5) Areas (5) Regions (0) Abstract: Heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust. Minimum He-3/He-4 ratios in surface fluids from the northern Basin and Range Province, western North America, increase systematically from low crustal values in the east to high mantle values in the west, a regional trend that correlates with the rates of active crustal deformation. The highest ratios occur where the extension and shear strain rates are greatest. The

369

Blunt-crack band propagation in finite-element analysis for concrete structures. [LMFBR  

SciTech Connect

The knowledge of concrete fracture is needed in nuclear reactor safety. The question of safety arises from the potential of concrete to crack under thermal loading. It has been postulated that structural concrete could be exposed to very high temperature, which may result from hot reactor coolant or even core debris coming in direct contact with the concrete. The utilization of the blunt crack approach for simulating concrete cracking in a general-purpose code is explored. The difficulties encountered in establishing the proper direction of crack propagation in an arbitrary discretization are described. Crack propagation is considered within the context of two types of solution techniques: (1) implicit solution of the static crack advance, and (2) explicit time integration using a dynamic relaxation technique to simulate the static crack advance. Also, in both solution techniques an elastic model is used to characterize the concrete.

Pfeiffer, P.A.; Bazant, Z.P.; Marchertas, A.H.

1983-01-01T23:59:59.000Z

370

Stress corrosion cracking of candidate waste container materials; Final report  

Science Conference Proceedings (OSTI)

Six alloys have been selected as candidate container materials for the storage of high-level nuclear waste at the proposed Yucca mountain site in Nevada. These materials are Type 304L stainless steel (SS). Type 316L SS, Incoloy 825, phosphorus-deoxidized Cu, Cu-30%Ni, and Cu-7%Al. The present program has been initiated to determine whether any of these materials can survive for 300 years in the site environment without developing through-wall stress corrosion cracks. and to assess the relative resistance of these materials to stress corrosion cracking (SCC)- A series of slow-strain-rate tests (SSRTs) and fracture-mechanics crack-growth-rate (CGR) tests was performed at 93{degree}C and 1 atm of pressure in simulated J-13 well water. This water is representative, prior to the widespread availability of unsaturated-zone water, of the groundwater present at the Yucca Mountain site. Slow-strain-rate tests were conducted on 6.35-mm-diameter cylindrical specimens at strain rates of 10-{sup {minus}7} and 10{sup {minus}8} s{sup {minus}1} under crevice and noncrevice conditions. All tests were interrupted after nominal elongation strain of 1--4%. Scanning electron microscopy revealed some crack initiation in virtually all the materials, as well as weldments made from these materials. A stress- or strain-ratio cracking index ranks these materials, in order of increasing resistance to SCC, as follows: Type 304 SS < Type 316L SS < Incoloy 825 < Cu-30%Ni < Cu and Cu-7%Al. Fracture-mechanics CGR tests were conducted on 25.4-mm-thick compact tension specimens of Types 304L and 316L stainless steel (SS) and Incoloy 825. Crack-growth rates were measured under various load conditions: load ratios M of 0.5--1.0, frequencies of 10{sup {minus}3}-1 Hz, rise nines of 1--1000s, and peak stress intensities of 25--40 MPa{center_dot}m {sup l/2}.

Park, J.Y.; Maiya, P.S.; Soppet, W.K.; Diercks, D.R.; Shack, W.J.; Kassner, T.F. [Argonne National Lab., IL (United States)

1992-06-01T23:59:59.000Z

371

Helium and Hydrogen Release Measurements on Various Alloys Irradiated in SINQ  

SciTech Connect

Three irradiations have been performed in the Swiss Spallation Neutron Source (SINQ) to establish a materials database for mixed proton and neutron fluxes for future spallation neutron and other accelerator sources. Materials included in the second irradiation, STIP-II, included mainly austenitic and martensitic steels. Samples of 316LN, F82H, Al, and Zircaloy-2 from STIP ?II have been analyzed for their total helium and hydrogen contents and their release characteristics. In terms of total gas content, the helium and hydrogen results are similar to those observed earlier from STIP-I. Specifically, the helium contents tended to be somewhat higher (up to 50%) than calculated for both low and high dose samples. 3He/4He ratios were generally in agreement with expectations except for the Ziracaloy-2 which showed very low values, likely from increased 3He generation from decay of irradiation-generated tritium. Hydrogen contents on the other hand tended inversely with dose, suggesting increased hydrogen loss at the higher dose (and higher temperature) locations from diffusion. Hydrogen levels in the Zircaloy were considerably higher than expected ({approx}10,000 to 25,000 appm), suggesting additional pickup of hydrogen from the irradiation environment. Hydrogen levels in the aluminum were similar to predicted. Helium and hydrogen release measurements from the temperature ramp experiments showed considerable levels of deuterium and tritium species which generally mirrored those of hydrogen. Hydrogen release occurred from about 300 for the aluminum to about 800 C for the Zircaloy-2. For the Zircaloy-2 and the steels, helium release began to occur at about 1100 C, which is consistent with previous measurements on irradiated steels. For the aluminum, helium release began at just under 600 C.

Oliver, Brian M.; Dai, Yong; Causey, Rion A.

2006-09-15T23:59:59.000Z

372

Integrating Broad-Band High-Fidelity Acoustic Emission Sensors and Array Processing to Study Drying Shrinkage Cracking in Concrete  

E-Print Network (OSTI)

, cracks can create stress concentrations which can cause further cracking at loads which are well under energy released from the formation of a crack is converted into stress waves which in turn produce Shrinkage Cracking in Concrete Gregory C. McLaskeya,1 , Steven D. Glasera , Christian U. Grosseb

Glaser, Steven D.

373

Solutions for Liquid Nitrogen Pre-Cooling in Helium Refrigeration Cycles  

E-Print Network (OSTI)

Pre-cooling of helium by means of liquid nitrogen is the oldest and one of the most common process features used in helium liquefiers and refrigerators. Its two principle tasks are to allow or increase the rate of pure liquefaction, and to permit the initial cool-down of large masses to about 80 K. Several arrangements for the pre-cooling process are possible depending on the desired application. Each arrangement has its proper advantages and drawbacks. The aim of this paper is to review the possible process solutions for liquid nitrogen pre-cooling and their particularities.

Wagner, U

2000-01-01T23:59:59.000Z

374

Detection and Imaging of He{sub 2} Molecules in Superfluid Helium  

SciTech Connect

We present data that show a cycling transition can be used to detect and image metastable He{sub 2} triplet molecules in superfluid helium. We demonstrate that limitations on the cycling efficiency due to the vibrational structure of the molecule can be mitigated by the use of repumping lasers. Images of the molecules obtained using the method are also shown. This technique gives rise to a new kind of ionizing radiation detector. The use of He{sub 2} triplet molecules as tracer particles in the superfluid promises to be a powerful tool for visualization of both quantum and classical turbulence in liquid helium.

Rellergert, W. G.; Cahn, S. B.; Garvan, A.; Hanson, J. C.; Lippincott, W. H.; Nikkel, J. A.; McKinsey, D. N. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States)

2008-01-18T23:59:59.000Z

375

Particle Detection in Superfluid Helium: R&D for Low Energy Solar Neutrinos  

DOE Green Energy (OSTI)

This report presents a summary of the results from R&D conducted as a feasibility study in the Department of Physics of Brown University for detection of low energy solar neutrinos utilizing a superfluid helium target. The report outlines the results in several areas: 1) development of experimental facilities, 2) energy deposition by electrons and alphas in superfluid helium, 3) development of wafer and metallic magnetic calorimeters, 4) background studies, 5) coded apertures and conceptual design, 6) Detection of single electrons and 7) a simulation of expected performance of a full scale device. Recommendations for possible future work are also presented. A bibliography of published papers and unpublished doctoral theses is included.

Lanou, Robert E., Jr.

2006-03-31T23:59:59.000Z

376

Nanometer-scale tunnel formation in metallic glass by helium ion irradiation  

SciTech Connect

We have shown that upon high fluence helium ion irradiation, metallic glass Cu{sub 50}Zr{sub 45}Ti{sub 5} becomes highly porous at the depth of the helium projected range. The resulting porous region is characterized by the formation of a tunnel like structure and self-linkage of nanometer size gas bubbles. Furthermore, the irradiation leads to the formation of nanometer size Cu{sub x}Zr{sub y} crystals that are randomly distributed. The results of this study indicate that the He-filled bubbles have attractive interactions and experience considerable mobility. Movement of the bubbles is believed to be assisted by ballistic collisions.

Shao Lin [Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843 (United States); Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Gorman, Brian P. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401 (United States); Aitkaliyeva, Assel [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); David Theodore, N. [CHD-Fab, Freescale Semiconductor, Inc., Chandler, Arizona 85224 (United States); Xie Guoqiang [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2012-07-23T23:59:59.000Z

377

High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium  

SciTech Connect

Work on the HTGR Helium Compatibility Task accomplished during the period March 31, 1977 through September 30, 1979, is documented in this report. Emphasis is on the results and analyses of creep data to 10,000 h and the detailed metallurgical evaluations performed on candidate alloy specimens tested for up to 10,000 h. Long-term creep and unstressed aging data in controlled-impurity helium and in air at 800, 900, and 1000/sup 0/C are reported for alloys included in the program in FY-76, including the wrought solid-solution-strengthened alloys, Hastelloy X, Hastelloy S, RA 333, and HD 556, and the centrifugally cast austenitic alloys, HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900.

Lechtenberg, T.A.; Stevenson, R.D.; Johnson, W.R.

1980-05-01T23:59:59.000Z

378

SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH A SOLAR CYCLE  

E-Print Network (OSTI)

SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH A SOLAR CYCLE Justin C. Kasper,1 Michael L. Stevens, and Alan J. Lazarus Kavli Institute for Astrophysics of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind

Richardson, John

379

Experimental measurement methods and data on irradiation of functional design materials by helium ions in linear accelerator  

E-Print Network (OSTI)

The experimental research on the irradiation of the functional design materials by the Helium ions in the linear accelerator is conducted. The experimental measurements techniques and data on the irradiation of the functional design materials by the Helium ions with the energy up to 4 MeV, including the detailed scheme of experimental measurements setup, are presented. The new design of accelerating structure of the IH-type such as POS-4, using the method of alternate-phase focusing with the step-by-step change of the synchronous phase along the focusing periods in a linear accelerator, is developed with the aim to irradiate the functional design materials by the Helium ions. The new design of the injector of the charged Helium ions with the energy of 120 KeV at the output of an accelerating tube and the accelerating structure of the type of POS-4 for the one time charged Helium ions acceleration in the linear accelerator are researched and developed. The special chamber for the irradiation of functional design materials by the Helium ions is also created. In the process of experiment, the temperature of a sample, the magnitude of current of Helium ions beam and the irradiation dose of sample are measured precisely. The experimental measurement setup and techniques are fully tested and optimized in the course of the research on the electro-physical properties of irradiated samples and the thermal-desorption of Helium ions in a wide range of temperatures

R. A. Anokhin; V. N. Voyevodin; S. N. Dubnyuk; A. M. Egorov; B. V. Zaitsev; A. F. Kobets; O. P. Ledenyov; K. V. Pavliy; V. V. Ruzhitsky; G. D. Tolstolutskaya

2013-09-03T23:59:59.000Z

380

"Cracking-the-whip" effect stretches driven polymers  

E-Print Network (OSTI)

Cracking the whip accelerates the tail of a chain to hit the air loudly and clearly. We proved that the similar acceleration effect causes coil deformation of driven chain-like polymers. We first preformed Monte Carlo simulations of a single driven polymer coil to demonstrate its deformation in company with faster or slower deviations of velocities. We then performed parallel Brownian Dynamics simulations to demonstrate that the coil deformation can be caused by the so-called "cracking-the-whip" effect due to non-synchronous biased Brownian motions of monomers inherited in Monte Carlo simulations. Since such non-synchronous motions represent random perturbations in the environmentally dependent potential energy landscape or mobility, reflecting heterogeneous dynamics of polymers in the liquid phase, our observations bring new insights into the non-linear dynamics of driven chain-like polymers.

Juan Li; Wenbing Hu

2013-10-31T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Modeling of solar receiver for cracking of liquid petroleum gas  

SciTech Connect

The paper presents the model of an industrial solar receiver/reactor for thermal cracking of liquid petroleum gas (LPG) at the typical temperature range of 800--850 C. The concentrated solar radiation enters the receiver located on the ground and provided with a compound parabolic concentrator (CPC) at the ceiling. This is achieved with a reflecting solar tower. The radiative model uses the classical concept of equivalent gray plane to represent a panel of 40 cracking tubes placed in parallel of a refractory wall of the receiver. The radiative flux distribution on each wall is calculated and the chemistry in each reactor tube is evaluated until convergence is achieved. The design of an industrial size receiver, its behavior, and performance have been evaluated using this model. The computer program based on this model was run for a variety of flow conditions, feed compositions, and pressures.

Segal, A.; Epstein, M. [Weizmann Inst. of Science, Rehovot (Israel). Solar Research Facilities Unit

1997-02-01T23:59:59.000Z

382

Environmentally assisted cracking of light-water reactor materials  

SciTech Connect

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.

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

1996-02-01T23:59:59.000Z

383

Method for making dense crack free thin films  

DOE Patents (OSTI)

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.

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

2007-01-16T23:59:59.000Z

384

Gas Turbine Rotor Life: General Electric FA Disc Cracking  

Science Conference Proceedings (OSTI)

This report covers the integrated results of the investigation into the occurrence of cooling slot and other rim cracking found in GE 7FA and 9FA gas turbine first and second stage rotor discs. Sections of the report address dimensional characterization, rim temperature measurement, metallurgical results, analytical methods, evaluation of mitigation approaches, and damage tolerance. Structural stress analysis assessed the effectiveness of the blend-polish-peen slot modification and a redesigned ...

2010-12-08T23:59:59.000Z

385

Stress relief cracking in creep resisting low alloy ferritic steels.  

E-Print Network (OSTI)

The Problem of Stress Relief Cracking in Low Alloy Steels During the welding of a ferritic steel, the HAZ adjacent to the weld transforms to austenite, the grains close to the fusion zone attaining particularly high tempel'ature and undergoing considerable... growth. At the same time, carbides tend to dissolve, dissolution being more complete in the coarse 14 grained region because it attains a higher temperature. The HAZ is cooled rapidly by the cold parent metal and, as a result, re- precipitation...

Tait, Robert Andrew

1976-10-26T23:59:59.000Z

386

Evaluation of Fundamental Linkage Among Stress Corrosion Cracking (SCC) Phenomena  

Science Conference Proceedings (OSTI)

Many in-core components of stainless steels in light water reactors (LWRs) are susceptible to a degradation process known as irradiation assisted stress corrosion cracking (IASCC). This report describes the results of environmental testing on irradiated Type 304 stainless steel in boiling water reactor (BWR) and pressurized water reactor (PWR) environments to assess their susceptibility to IASCC. The work was sponsored by the Cooperative IASCC Research (CIR I) Program, an international research effort ma...

2002-10-23T23:59:59.000Z

387

Computer Simulation of Intergranular Stress Corrosion Cracking via Hydrogen Embrittlement  

DOE Green Energy (OSTI)

Computer simulation has been applied to the investigation of intergranular stress corrosion cracking in Ni-based alloys based on a hydrogen embrittlement mechanism. The simulation employs computational modules that address (a) transport and reactions of aqueous species giving rise to hydrogen generation at the liquid-metal interface, (b) solid state transport of hydrogen via intergranular and transgranular diffusion pathways, and (c) fracture due to the embrittlement of metallic bonds by hydrogen. A key focus of the computational model development has been the role of materials microstructure (precipitate particles and grain boundaries) on hydrogen transport and embrittlement. Simulation results reveal that intergranular fracture is enhanced as grain boundaries are weakened and that microstructures with grains elongated perpendicular to the stress axis are more susceptible to cracking. The presence of intergranular precipitates may be expected to either enhance or impede cracking depending on the relative distribution of hydrogen between the grain boundaries and the precipitate-matrix interfaces. Calculations of hydrogen outgassing and in gassing demonstrate a strong effect of charging method on the fracture behavior.

Smith, R.W.

2000-04-01T23:59:59.000Z

388

Comparing Methods of Estimating Crack Volume in Shrink-Swell Soils  

E-Print Network (OSTI)

Predicting soil crack formation and closure in high shrink-swell soils is crucial for modeling water movement and solute transport. However, soil cracking, as it occurs in natural conditions, is not well understood. The objectives of this research are to 1) compare shrinking and swelling of two Vertisols with different mineralogy and 2) compare two methods for estimating soil crack volume. The first soil monitored, Ships Clay (Very-fine, mixed, thermic Chromic Hapluderts) has mixed mineralogy and is located in Snook, TX. The second soil monitored is a Burleson Clay (Fine, smectitic, thermic Udic Haplusterts), which has smectitic mineralogy and is located 1 mile southwest of the Ships site. During two drying events, vertical subsidence and cracking were measured on both soils. Vertical subsidence was measured at three locations in each soil with rods fixed at four depths. Rod movement was converted to soil crack volume by assuming equi-dimensional shrinkage. A second method for estimating crack volume used direct measurements of cracks in the field. This second method was time consuming and the accuracy is unknown. A neutron moisture meter access tube was installed to measure soil moisture at each subsidence location. A total of 20 levling and moisture measurements were completed and 10 hand measurements of cracking were made. At the completion of the study, full characterization of each measurement location was performed, including COLE measurements. These COLE measurements were used as a third method of estimating crack volume in relation to soil moisture. Total crack volume will be compared at both sites to show the differences in the drying and cracking patterns. Crack volume as a function of moisture will be used to show how soil cracking and moisture relate. The two methods of estimating crack volume will be compared to see where possible cracking was measured with subsidence but not seen visually. The results showed the leveling-predicted crack volume was ten times that of the hand measured crack volume but followed the same temporal trend. The leveling-predicted crack volume is the most accurate of the three methods. COLE was also shown to be a good predictor a soils shrink-swell potential.

Rivera, Leonardo D.

2011-08-04T23:59:59.000Z

389

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

DOE Green Energy (OSTI)

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.

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

2002-08-01T23:59:59.000Z

390

First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium  

SciTech Connect

While metallic fuels have a long history of reactor use, their fundamental physical and thermodynamic properties are not well understood. Many metallic nuclear fuels are body-centered cubic alloys of uranium that swell under fission conditions, creating fission product gases such as helium, xenon and krypton. In this paper, helium, xenon, and krypton point defects are investigated in the a and ? phases of metallic uranium using first principles calculations. A density functional theory (DFT) framework is utilized with projector augmented-wave (PAW) pseudopotentials. Formation and incorporation energies of He, Xe, and Kr are calculated at various defect positions for the prediction of fission gas behavior in uranium. In most cases, defect energies follow a size effect, with helium incorporation and formation energies being the smallest. The most likely position for the larger Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed. This is the first detailed study of the stability and incorporation of fission gases in uranium.

B. Beeler; B. Good; S. Rashkeev; M. Baskes; M. Okuniewski

2012-06-01T23:59:59.000Z

391

A Concept for A Dark Matter Detector Using Liquid Helium-4  

E-Print Network (OSTI)

Direct searches for light dark matter particles (mass $<10$ GeV) are especially challenging because of the low energies transferred in elastic scattering to typical heavy nuclear targets. We investigate the possibility of using liquid Helium-4 as a target material, taking advantage of the favorable kinematic matching of the Helium nucleus to light dark matter particles. Monte Carlo simulations are performed to calculate the charge, scintillation, and triplet helium molecule signals produced by recoil He ions, for a variety of energies and electric fields. We show that excellent background rejection can be achieved based on the ratios between different signal channels. We also present some concepts for a liquid-helium-based dark matter detector. Key to the proposed approach is the use of a large electric field to extract electrons from the event site, and the amplification of this charge signal, through proportional scintillation, liquid electroluminescence, or roton emission. The sensitivity of the proposed detector to light dark matter particles is estimated for various electric fields and light collection efficiencies.

Wei Guo; Daniel N. McKinsey

2013-02-03T23:59:59.000Z

392

Helium Adsorption in Silica Aerogel near the Liquid-Vapor Critical Point  

E-Print Network (OSTI)

We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95 % and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel’s very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales. I.

Tobias Herman; James Day; John Beamish

2008-01-01T23:59:59.000Z

393

A temperature-controlled device for volumetric measurements of Helium adsorption in porous  

E-Print Network (OSTI)

a set-up for studying adsorption of helium in silica aerogels, where the adsorbed amount is easily- dation experiments and a first application to aerogels. This device is well adapted to study hysteresis, such as grafoil, carbon nanotubes, or silica glasses. The case of silica aerogels has attracted attention

Paris-Sud XI, Université de

394

Helium adsorption in silica aerogel near the liquid-vapor critical point  

E-Print Network (OSTI)

We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95% and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel's very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales.

Tobias Herman; James Day; John Beamish

2005-05-18T23:59:59.000Z

395

Electron-impact excitation-autoionization of helium in the S-wave limit  

Science Conference Proceedings (OSTI)

Excitation of the autoionizing states of helium by electron impact is shown in calculations in the s-wave limit to leave a clear signature in the singly differential cross section for the (e,2e) process. It is suggested that such behavior should be seen generally in (e,2e) experiments on atoms that measure the single differential cross section.

Horner, Daniel A.; McCurdy, C. William; Rescigno, Thomas N.

2004-10-01T23:59:59.000Z

396

RECONCILING THE GALACTIC BULGE TURNOFF AGE DISCREPANCY WITH ENHANCED HELIUM ENRICHMENT  

SciTech Connect

We show that the factor {approx}2 discrepancy between spectroscopic and photometric age determinations of the Galactic bulge main-sequence turnoff can be naturally explained by positing an elevated helium enrichment for the bulge relative to that assumed by standard isochrones. Helium enhancement relative to standard isochrones is confirmed at the 2.3{sigma} level. We obtain an upper bound on the helium enrichment for the metal-rich ([Fe/H] Almost-Equal-To +0.30) stars of {Delta}Y Almost-Equal-To +0.11 relative to canonical expectations, given the requirement that the spectroscopic and photometric ages be consistent and the limiting condition of instantaneous star formation. We discuss phenomenological evidence that the bulge may have had a chemical evolution that is distinct from the solar neighborhood in this manner, and we make several testable predictions. Should this emerging picture of the bulge as helium-enhanced hold, it will require the development of new isochrones, new model atmospheres, and modified analysis and cosmological interpretation of the integrated light of other bulges and elliptical galaxies.

Nataf, David M.; Gould, Andrew P. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

2012-06-01T23:59:59.000Z

397

Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak  

DOE R&D Accomplishments (OSTI)

Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

1993-03-00T23:59:59.000Z

398

On the micromechanisms of fatigue-crack propagation in aluminum- lithium alloys: Sheet vs. plate material  

Science Conference Proceedings (OSTI)

Micromechanisms influencing the propagation of long (>10 mm) fatigue cracks in aluminum-lithium alloys are examined by specifically comparing crack-growth kinetics in a peak-aged Al-Li-Cu-Zr alloy 2090, processed as 1.6-mm thin (T83) sheet and 12.7-mm thick (T81) plate. It is found that in general crack-growth rates are significantly faster in the sheet material at equivalent stress-intensity levels, due to differences in the role of crack-tip shielding, resulting from crack deflection and consequent crack closure from wedging of fracture-surface asperities. Microstructurally, such differences are related to variations in the degree of recrystallization, grain structure and deformation texture in the two wrought-product forms. 14 refs., 4 figs.

Rao Venkateswara, K.T.; Ritchie, R.O. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Bucci, R.J. (Aluminum Co. of America, Alcoa Center, PA (United States). Alcoa Labs.)

1989-12-01T23:59:59.000Z

399

Shock Experiments on Pre-Compressed Fluid Helium and Hydrogen  

DOE Green Energy (OSTI)

The summary of the report is: (1) We have proposed, used, and validated (using aerogel and D{sub 2}) quartz as an impedance-match standard; (2) We have collected extensive EOS data on He, D{sub 2}, and H{sub 2} at conditions relevant to giant planet interiors; (3) We observe relatively soft EOS's for all three materials; (4) We observe temperature-induced ionization in He (5) Our analysis indicates a strong electronic-gap density dependence; and (6) Our results favor planetary models for Jupiter that include partitioning of heavy elements into a relatively large core.

Eggert, J

2009-11-05T23:59:59.000Z

400

Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results  

SciTech Connect

The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243{degrees}C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling.

Li, Y.Y.

1997-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

LARGE NUMBERS OF UNDETECTED CRACKS IN THE WORLD’S PWRS  

E-Print Network (OSTI)

Documents of the Davis-Besse incident reveal a strong possibility that there are large numbers of undetected cracks in the world’s pressurized water reactors, particularly in the US. This suspicion has been confirmed by the discovery of an additional crack at Davis-Besse itself. (568.5402) NIRS/WISE Amsterdam – The cracks are nothing new: they were first discovered in Bugey-3,

unknown authors

2002-01-01T23:59:59.000Z

402

Survey of helium in soils and soil gases and mercury in soils at Roosevelt Hot Springs Known Geothermal Resource Area, Utah  

SciTech Connect

The concentrations of helium and mercury in soils and of helium in soil gases were surveyed in part of the Roosevelt Hot Springs Known Geothermal Resource Area to see what relationship helium and mercury concentrations might have to geothermal features of the area. High concentrations of helium occurred over the producing geothermal field, in an area of high temperature gradients. Low concentrations of helium in soils occurred over an area of visible hydrotheormal activity. High concentrations of mercury coincided with areas of high thermal gradients and low resistivity.

Hinkle, M.E.

1980-01-01T23:59:59.000Z

403

Elevated-Temperature Creep-Fatigue Crack-Growth Behavior of ...  

Science Conference Proceedings (OSTI)

the nickel-base HAYNES R-41, HAYNES 230 and HASTELLOY. X superalloys at temperatures ... The crack-growth tests for R-41 alloy were conducted using a.

404

An introduction to crack spreads - Today in Energy - U.S ...  

U.S. Energy Information Administration (EIA)

Crack spreads are differences between wholesale petroleum product prices and crude oil prices. These spreads are often used to estimate refining margi ...

405

A model of crack based on dislocations in smectic A liquid crystals  

E-Print Network (OSTI)

A plastic crack model for smectic A liquid crystals under longitudinal shear is suggested. The solution of screw dislocation in smectic A is the key in which the correct result is just obtained by overcoming a longstanding puzzle [19]. We further use the dislocation pile-up principle and the singular integral equation method, construct the solution of the crack in the phase. From the solution we can determine the size of the plastic zone at the crack tip and the crack tip opening (tearing) displacement, which are parameters being relevant to the local stability/instability of materials. The results may be useful in developing soft-matter mechanics.

Tian You Fan

2012-10-30T23:59:59.000Z

406

Cyclic Deformation and Fatigue Cracking Mechanisms of F.C.C. ...  

Science Conference Proceedings (OSTI)

Fatigue Crack Tip Mechanics Following a Tensile Overload · Fatigue Weak-Link Density and Strength Distribution in High Strength Al Wrought and Cast Alloys.

407

Manufacturing of Crack-Free Hastelloy-X Components by Selective ...  

Science Conference Proceedings (OSTI)

Lubricants in Deposition and Machining of Wire and Arc Additive Manufactured Structures · Manufacturing of Crack-Free Hastelloy-X Components by Selective ...

408

Physics-Based Stress Corrosion Cracking Component Reliability  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Physics-Based Stress Corrosion Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework Draft Report Supporting Technology Inputs to the Risk- Informed Safety Margin Characterization Pathway of the DOE Light Water Reactor Sustainability Program Stephen D. Unwin Kenneth I. Johnson Robert F. Layton Peter P. Lowry Scott E. Sanborn Mychailo B. Toloczko PNNL-20596 July 2011 Physics-Based SCC Reliability Model in a Cumulative Damage Framework 2 Physics-Based SCC Reliability Model in a Cumulative Damage Framework 3 Table of Contents Executive Summary............................................................................... 4 1. Introduction .......................................................................... 5

409

Repair welding of fusion reactor components. Second year technical report  

SciTech Connect

Experiments have shown that irradiated Type 316 stainless steel is susceptible to heat-affected-zone (HAZ) cracking upon cooling when welded using the gas tungsten arc (GTA) process under lateral constraint. The cracking has been hypothesized to be caused by stress-assisted helium bubble growth and rupture at grain boundaries. This study utilized an experimental welding setup which enabled different compressive stresses to be applied to the plates during welding. Autogenous GTA welds were produced in Type 316 stainless steel doped with 256 appm helium. The application of a compressive stress, 55 MPa, during welding suppressed the previously observed catastrophic cracking. Detailed examinations conducted after welding showed a dramatic change in helium bubble morphology. Grain boundary bubble growth along directions parallel to the weld was suppressed. Results suggest that stress-modified welding techniques may be used to suppress or eliminate helium-induced cracking during joining of irradiated materials.

Chin, B.A.

1993-05-15T23:59:59.000Z

410

Repair welding of fusion reactor components  

SciTech Connect

Experiments have shown that irradiated Type 316 stainless steel is susceptible to heat-affected-zone (HAZ) cracking upon cooling when welded using the gas tungsten arc (GTA) process under lateral constraint. The cracking has been hypothesized to be caused by stress-assisted helium bubble growth and rupture at grain boundaries. This study utilized an experimental welding setup which enabled different compressive stresses to be applied to the plates during welding. Autogenous GTA welds were produced in Type 316 stainless steel doped with 256 appm helium. The application of a compressive stress, 55 MPa, during welding suppressed the previously observed catastrophic cracking. Detailed examinations conducted after welding showed a dramatic change in helium bubble morphology. Grain boundary bubble growth along directions parallel to the weld was suppressed. Results suggest that stress-modified welding techniques may be used to suppress or eliminate helium-induced cracking during joining of irradiated materials.

Chin, B.A.

1993-05-15T23:59:59.000Z

411

Plant Design and Cost Estimation of a Natural Circulation Lead-Bismuth Reactor with Helium Power Conversion Cycle  

E-Print Network (OSTI)

The analysis of an indirect helium power conversion system with lead-bismuth natural circulation primary system has been performed. The work of this report is focused on 1) identifying the allowable design region for the ...

Kim, D.

412

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: Effect of helium  

E-Print Network (OSTI)

Prominences are partially ionized, magnetized plasmas embedded in the solar corona. Damped oscillations and propagating waves are commonly observed. These oscillations have been interpreted in terms of magnetohydrodynamic (MHD) waves. Ion-neutral collisions and non-adiabatic effects (radiation losses and thermal conduction) have been proposed as damping mechanisms. We study the effect of the presence of helium on the time damping of non-adiabatic MHD waves in a plasma composed by electrons, protons, neutral hydrogen, neutral helium (He I), and singly ionized helium (He II) in the single-fluid approximation. The dispersion relation of linear non-adiabatic MHD waves in a homogeneous, unbounded, and partially ionized prominence medium is derived. The period and the damping time of Alfven, slow, fast, and thermal waves are computed. A parametric study of the ratio of the damping time to the period with respect to the helium abundance is performed. The efficiency of ion-neutral collisions as well as thermal conduc...

Soler, R; Ballester, J L

2009-01-01T23:59:59.000Z

413

Condensation of helium in aerogels as an experimental realization of the out-of-equilibrium Random Field Ising Model  

E-Print Network (OSTI)

Condensation of helium in aerogels as an experimental realization of the out-of-equilibrium Random that the condensation of 4He in base-catalysed silica aerogels of large porosity presents a similar out

Recanati, Catherine

414

Condensation of helium in aerogels as an experimental realization of the out-of-equilibrium Random Field Ising Model  

E-Print Network (OSTI)

Condensation of helium in aerogels as an experimental realization of the out-of-equilibrium Random-catalysed silica aerogels of large porosity presents a similar out-of-equilibrium behavior when the temperature

415

A Liquid-Helium-Cooled Absolute Reference Cold Load forLong-Wavelength Radiometric Calibration  

SciTech Connect

We describe a large (78-cm) diameter liquid-helium-cooled black-body absolute reference cold load for the calibration of microwave radiometers. The load provides an absolute calibration near the liquid helium (LHe) boiling point, accurate to better than 30 mK for wavelengths from 2.5 to 25 cm (12-1.2 GHz). The emission (from non-LHe temperature parts of the cold load) and reflection are small and well determined. Total corrections to the LHe boiling point temperature are {le} 50 mK over the operating range. This cold load has been used at several wavelengths at the South Pole and at the White Mountain Research Station. In operation, the average LHe loss rate was {le} 4.4 l/hr. Design considerations, radiometric and thermal performance and operational aspects are discussed. A comparison with other LHe-cooled reference loads including the predecessor of this cold load is given.

Bensadoun, M.; Witebsky, C.; Smoot, George F.; De Amici,Giovanni; Kogut, A.; Levin, S.

1990-05-01T23:59:59.000Z

416

Laser spectroscopy of the antiprotonic helium atom – its energy levels and state lifetimes  

E-Print Network (OSTI)

The antiprotonic atom is a three-body exotic system consisting of an antiproton, an electron and a helium nucleus. Its surprising longevity was found and has been studied for more than 10 years. In this work, transition energies and lifetimes of this exotic atom were systematically studied by using the antiproton beam of AD(Antiproton Decelerator) facility at CERN, with an RFQ antiproton decelerator, a narrow-bandwidth laser, Cerenkov counters with fast-response photomultiplier tubes, and cryogenic helium target systems. Thirteen transition energies were determined with precisions of better than 200 ppb by a laser spectroscopy method, together with the elimination of the shift effect caused by collisions with surrounding atoms. Fifteen lifetimes (decay rates) of short-lived states were determined from the time distributions of the antiproton-annihilation signals and the resonance widths of the atomic spectral lines. The relation between the magnitude of the decay rates and the transition multipolarity was inv...

Hidetoshi, Yamaguchi

2003-01-01T23:59:59.000Z

417

Final Technical Report for the Neutron Detection without Helium-3 Project  

SciTech Connect

This report details the results of the research and development work accomplished for the ‘Neutron Detection without Helium-3’ project conducted during the 2011-2013 fiscal years. The primary focus of the project was to investigate commercially available technologies that might be used in safeguards applications in the relatively near term. Other technologies that are being developed may be more applicable in the future, but were outside the scope of this study.

Ely, James H.; Bliss, Mary; Kouzes, Richard T.; Lintereur, Azaree T.; Robinson, Sean M.; Siciliano, Edward R.; Swinhoe, Martyn T.; Woodring, Mitchell L.

2013-11-01T23:59:59.000Z

418

Measurement of the magnetic fine structure of the 10G and 10H states of helium  

Science Conference Proceedings (OSTI)

The magnetic fine-structure intervals separating the four members of the 10G and 10H manifolds of helium have been measured with a precision of 0.1% using a fast-beam microwave-optical resonance technique. The results are found to be in good agreement with theory, illustrating that the two-electron wave function is very nearly hydrogenic. The measurements are also used to determine the small exchange energies of the 10G and 10H states.

Hessels, E.A.; Sturrus, W.G.; Lundeen, S.R.; Cok, D.R.

1987-06-01T23:59:59.000Z

419

A Simulation Study for the Virtual Commissioning of the CERN Central Helium Liquefier  

E-Print Network (OSTI)

This paper describes the implication of dynamic simulation in cryogenics processes. The simulation aims to prepare plant commissioning and operation, and to validate the efficiency of the new process control logic. PLC programs have been tested on a process simulator integrating physical models of valves, heat exchangers, turbines, phase separator, and helium data. The model has shown the capacity to reproduce cold-box dynamic behaviour, from 300 K to 4.5 K.

Rogez, E; Moraux, A; Pezzetti, M; Gayet, P; Coppier, H

2008-01-01T23:59:59.000Z

420

Modeling and Simulation Optimization and Feasibility Studies for the Neutron Detection without Helium-3 Project  

Science Conference Proceedings (OSTI)

This report details the results of the modeling and simulation work accomplished for the ‘Neutron Detection without Helium-3’ project during the 2011 and 2012 fiscal years. The primary focus of the project is to investigate commercially available technologies that might be used in safeguards applications in the relatively near term. Other technologies that are being developed may be more applicable in the future, but are outside the scope of this study.

Ely, James H.; Siciliano, Edward R.; Swinhoe, Martyn T.; Lintereur, Azaree T.

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

SUPERBURST MODELS FOR NEUTRON STARS WITH HYDROGEN- AND HELIUM-RICH ATMOSPHERES  

SciTech Connect

Superbursts are rare day-long type I X-ray bursts due to carbon flashes on accreting neutron stars in low-mass X-ray binaries. They heat the neutron star envelope such that the burning of accreted hydrogen and helium becomes stable, and the common shorter X-ray bursts are quenched. Short bursts reappear only after the envelope cools down. We study multi-zone one-dimensional models of the neutron star envelope, in which we follow carbon burning during the superburst, and we include hydrogen and helium burning in the atmosphere above. We investigate the cases of both a solar-composition and a helium-rich atmosphere. This allows us to study for the first time a wide variety of thermonuclear burning behavior as well as the transitions between the different regimes in a self-consistent manner. For solar composition, burst quenching ends much sooner than previously expected. This is because of the complex interplay between the 3{alpha}, hot CNO, and CNO breakout reactions. Stable burning of hydrogen and helium transitions via marginally stable burning (mHz quasi-periodic oscillations) to less energetic bursts with short recurrence times. We find a short-lived bursting mode where weaker and stronger bursts alternate. Eventually the bursting behavior changes back to that of the pre-superburst bursts. Because of the scarcity of observations, this transition has not been directly detected after a superburst. Using the MINBAR burst catalog we identify the shortest upper limit on the quenching time for 4U 1636-536, and derive further constraints on the timescale on which bursts return.

Keek, L. [National Superconducting Cyclotron Laboratory, Department of Physics and Astronomy, and Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States); Heger, A. [School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); In 't Zand, J. J. M., E-mail: keek@nscl.msu.edu [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands)

2012-06-20T23:59:59.000Z

422

Influence of Radiolysis and Hydrogen Embrittlement on the In-Service Cracking of PWR Internal Structures  

Science Conference Proceedings (OSTI)

Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steel components exposed to a high neutron flux in light water reactors is becoming an increasing concern for nuclear power plant owners. This study investigates the interaction between hydrogen in the metal and the water environment that may exacerbate the cracking process in PWRs.

1999-11-10T23:59:59.000Z

423

On saturation-strip model of a permeable crack in a piezoelectric ceramic  

E-Print Network (OSTI)

, h0, in the analysis of electrical and mechanical fields in the vicinity of a permeable crack tip under both mechanical as well electrical loads. Both local and global energy release rates. This permeable saturation crack model reveals that there exists a possible leaky mode for electrical field, which

Li, Shaofan

424

Thermal stress cracking and the enhancement of heat extraction from fractured geothermal reservoirs  

DOE Green Energy (OSTI)

Given sufficient time, the extraction of heat from geothermal reservoirs formed by the hydraulic fracturing of competent rock will eventually result in the formation of thermal stress cracks in the reservoir. These cracks penetrate the rock in a manner such that the penetration-to-spacing ratio is approximately one. The penetration depends upon the extent of cooling and the square root of time. Initially then, the cracks are closely spaced and penetrate but little, so that a crazing pattern is apparent; but with increasing time some of these cracks, now more widely spaced, grow deeper. Eventually these larger cracks attain a critical aperture such that significant rates of water flow can be established within them and thus the newly created heat transfer area becomes useful for heat extraction. At the same time that cracks are forming within the main reservoir, thermal cracking also occurs in the wellbores that communicate with the reservoir. These cracks eventually convey water to and from the reservoir, thus leading to a decrease in the flow impedances that are often concentrated in the wellbore regions.

Murphy, H.D.

1978-04-01T23:59:59.000Z

425

Apparatus and method for prevention of cracking in welded brittle alloys  

DOE Patents (OSTI)

An apparatus and method for reducing cracking in a heated material as the material cools. The apparatus includes a variable frequency electric signal generator that is coupled to a transducer. The transducer produces a variable frequency acoustic signal in response to the variable frequency electric signal, which is applied to the heated material to reduce cracking as the material cools.

Kronberg, James W. (Aiken, SC); Younkins, Robert M. (New Ellenton, SC)

2000-01-01T23:59:59.000Z

426

Delamination of a sensitized commercial AlMg alloy during fatigue crack growth  

E-Print Network (OSTI)

as sensitization to corrosion and stress corrosion cracking [1,3,4,8], with exposure to tem- peratures between 50,9­12]. The presence and growth of b-phase have been shown to severely degrade the corrosion resistance and stressDelamination of a sensitized commercial Al­Mg alloy during fatigue crack growth J.K. Brosi and J

Rollins, Andrew M.

427

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

E-Print Network (OSTI)

the free energy, and thus the energy barrier, via numerous competing mech- anisms like stress corrosion speed of crack growth with increasing G; a weak stress- sensitive regime II follows where transportAverage crack front velocity during subcritical fracture propagation in a heterogeneous medium

Ampuero, Jean Paul

428

Prediction of Environmental Crack Growth in Nuclear Power Plant Components: Volumes 1-3  

Science Conference Proceedings (OSTI)

In-service assessment of crack growth rates plays a crucial role in decisions involving component integrity and life. The research presented in this three-volume report examines many important aspects of the crack tip damage processes in aqueous environments, providing an improved scientific basis for life prediction technology development.

1993-11-04T23:59:59.000Z

429

Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2  

Science Conference Proceedings (OSTI)

Fatigue crack growth rates of Ti 6-2-2-2-2 as a function of stress ratio, temperature (24 or 177 degrees C), tensile orientation and environment (laboratory air or ultrahigh vacuum) are presented. Fatigue crack growth rates of Ti 6-2-2-2-2 are also compared ...

Smith Stephen W.; Piascik Robert S.

2001-03-01T23:59:59.000Z

430

Behavior of Stress Corrosion Cracking for Type 316L Stainless Steel ...  

Science Conference Proceedings (OSTI)

Crack Growth Rates of Irradiated Commercial Stainless Steels in BWR and PWR ... Detailed Root Cause Analysis of SG Tube ODSCC Indications within the Tube Sheets of NPP Biblis Unit A .... Radiation Damage in Fe-C-Met Model Alloys ... Stress Corrosion Cracking Behavior near the Fusion Boundary of Dissimilar Weld

431

Factors influencing helium measurements for detection of control rod failures in BWR  

SciTech Connect

Much effort has been made to minimize the number and consequences of fuel failures at nuclear power plants. The consequences of control rod failures have also gained an increased attention. In this paper we introduce a system for on-line surveillance of control rod integrity which has several advantages comparing to the surveillance methods available today in boiling water reactors (BWRs). This system measures the helium released from failed control rods containing boron carbide (B4C). However, there are a number of factors that might influence measurements, which have to be taken into consideration when evaluating the measured data. These factors can be separated into two groups: 1) local adjustments, made on the sampling line connecting the detector to the off-gas system, and 2) plant operational parameters. The adjustments of the sample line conditions include variation of gas flow rate and gas pressure in the line. Plant operational factors that may influence helium measurements can vary from plant to plant. The factors studied at Leibstadt nuclear power plant (KKL) were helium impurities in injected hydrogen gas, variation of the total off-gas flow and regular water refill. In this paper we discuss these factors and their significance and present experimental results of measurements at KKL. (authors)

Larsson, I.; Sihver, L. [Div. of Nuclear Engineering, Dept. of Applied Physics, Chalmers Univ. of Technology, SE-412 96 Gothenburg (Sweden); Loner, H.; Ledergerber, G. [Kernkraftwerk Leibstadt, CH-5325 Leibstadt (Switzerland); Schnurr, B. [E.ON Kernkraft GmbH, D-84049 Essenbach (Germany)

2012-07-01T23:59:59.000Z

432

A systematic regional trend in helium isotopes across the northernbasin and range province, Western North America  

Science Conference Proceedings (OSTI)

An extensive study of helium isotopes in fluids collectedfrom surface springs, fumaroles and wells across the northern Basin andRange Province reveals a systematic trend of decreasing 3He/4He ratiosfrom west to east. The western margin of the Basin and Range ischaracterized by mantle-like ratios (6-8 Ra) associated with active orrecently active crustal magma systems (e.g., Coso, Long Valley,Steamboat, and the Cascade volcanic complex). Moving towards the east,the ratios decline systematically to a background value of ~;0.1 Ra. Theregional trend is consistent with extensive mantle melting concentratedalong the western margin and is coincident with an east-to-west increasein the magnitude of northwest strain. The increase in shear strainenhances crustal permeability resulting in high vertical fluid flow ratesthat preserve the high helium isotope ratios at the surface. Superimposedon the regional trend are "helium spikes," local anomalies in the heliumisotope composition. These "spikes" reflect either local zones of mantlemelting or locally enhanced crustal permeability. In the case of theDixie Valley hydrothermal system, it appears to be a combination ofboth.

Kennedy, B. Mack; van Soest, Matthijs C.

2006-05-01T23:59:59.000Z

433

FLOATING PRESSURE CONVERSION AND EQUIPMENT UPGRADES OF TWO 3.5KW, 20K, HELIUM REFRIGERATORS  

SciTech Connect

Two helium refrigerators, each rated for 3.5 KW at 20 K, are used at NASA's Johnson Space Center (JSC) in Building No. 32 to provide cryogenic-pumping within two large thermal-vacuum chambers. These refrigerators were originally commissioned in 1996. New changes to the controls of these refrigerators were recently completed. This paper describes some of the control issues that necessitated the controls change-over. It will describe the modifications and the new process control which allows the refrigerators to take advantage of the Ganni Cycle “floating pressure” control technology. The controls philosophy change-over to the floating pressure control technology was the first application on a helium gas refrigeration system. Previous implementations of the floating pressure technology have been on 4 K liquefaction and refrigeration systems, which have stored liquid helium volumes that have level indications used for varying the pressure levels (charge) in the system for capacity modulation. The upgrades have greatly improved the performance, stability, and efficiency of these two refrigerators. The upgrades have also given the operators more information and details about the operational status of the main components (compressors, expanders etc.) of the refrigerators at all operating conditions (i.e. at various loads in the vacuum chambers). The performance data of the two systems, pre and post upgrading are presented.

J. Homan, V. Ganni, A. Sidi-Yekhlef, J. Creel, R. Norton, R. Linza, G. Vargas, J. Lauterbach, J. Urbin, D. Howe

2010-04-01T23:59:59.000Z

434

Determination of tritium permeation rate through T-22 in GCFR helium environment  

SciTech Connect

Measurements were made on tritium permeation rates through T-22 tubular samples in the temperature range of 300/sup 0/ to 550/sup 0/C. The tritium source consists of tritium in helium containing hydrogen at 6 vol % and sufficient water vapor to maintain a hydrogen-to-water-pressure ratio of 10, the total pressure being 1.01 x 10/sup 5/ Pa (1 atm). Two tritium sources at specific activities of 2.6 x 10/sup -3/ and 3.1 x 10/sup -2/ ..mu..Ci/std cc, respectively, were used for determining how the permeation rate varies with tritium concentration. The T-22 tubular samples have a wall thickness of 0.437 x 10/sup -2/ m (0.172 in.), and two samples are used for checking the reproducibility of the results. During the measurements, the tritium diffusing through the wall of the sample is swept out with a helium-steam mixture by bubbling helium at atmospheric pressure through a water reservoir maintained at 90/sup 0/C.

Yang, L.; Baugh, W.A.

1980-01-01T23:59:59.000Z

435

Spectroscopic studies on the formation of coke on individual Fluid Catalytic Cracking particles: the effect of poisoning metal compounds.  

E-Print Network (OSTI)

??The formation of coke on individual Fluid Catalytic Cracking (FCC) catalyst particles was studied using UV/Vis microspectroscopy and confocal fluorescence microscopy, with n-hexane cracking as… (more)

Goetze, J.G.

2013-01-01T23:59:59.000Z

436

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

SciTech Connect

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.

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

437

Assessment of Cracks in Stress Concentration Regions with Localized Plastic Zones  

SciTech Connect

Marty brittle fracture evaluation procedures include plasticity corrections to elastically computed stress intensity factors. These corrections, which are based on the existence of a plastic zone in the vicinity of the crack tip, can overestimate the plasticity effect for a crack embedded in a stress concentration region in which the elastically computed stress exceeds the yield strength of the material in a localized zone. The interactions between the crack, which acts to relieve the high stresses driving the crack, plasticity effects in the stress concentration region, and the nature and source of the loading are examined by formulating explicit flaw finite element models for a crack emanating from the root of a notch located in a panel subject to an applied tensile stress. The results of these calculations provide conditions under which a crack-tip plasticity correction based on the Irwin plastic zone size overestimates the plasticity effect. A failure assessment diagram (FAD) curve is used to characterize the effect of plasticity on the crack driving force and to define a less restrictive plasticity correction for cracks at notch roots when load-controlled boundary conditions are imposed. The explicit flaw finite element results also demonstrate that stress intensity factors associated with load-controlled boundary conditions, such as those inherent in the ASME Boiler and Pressure Vessel Code as well as in most handbooks of stress intensity factors, can be much higher than those associated with displacement-controlled conditions, such as those that produce residual or thermal stresses. Under certain conditions, the inclusion of plasticity effects for cracks loaded by displacement-controlled boundary conditions reduces the crack driving force thus justifying the elimination of a plasticity correction for such loadings. The results of this study form the basis for removing unnecessary conservatism from flaw evaluation procedures that utilize plasticity corrections.

Friedman, E.

1998-11-25T23:59:59.000Z

438

BWRVIP-99-A: BWR Vessel and Internals Project, Crack Growth Rates in Irradiated Stainless Steels in BWR Internal Components  

Science Conference Proceedings (OSTI)

The BWR Vessel and Internals Project (BWRVIP) has developed methodologies to evaluate crack growth in internal components of stainless steel and nickel-base alloys in the BWR vessel. One BWRVIP report—BWRVIP-14—developed an approach to evaluate crack growth by intergranular stress corrosion cracking in austenitic stainless steel core shrouds exposed to a limited amount of neutron irradiation. Subsequently another report—BWRVIP-99—was prepared to provide a crack growth methodology applicable to irradiated...

2008-11-24T23:59:59.000Z

439

LATERALLY PROPAGATING DETONATIONS IN THIN HELIUM LAYERS ON ACCRETING WHITE DWARFS  

SciTech Connect

Theoretical work has shown that intermediate mass (0.01 M{sub Sun} < M{sub He} < 0.1 M{sub Sun }) helium shells will unstably ignite on the accreting white dwarf (WD) in an AM CVn binary. For more massive (M > 0.8 M{sub Sun }) WDs, these helium shells can be dense enough (>5 Multiplication-Sign 10{sup 5} g cm{sup -3}) that the convectively burning region runs away on a timescale comparable to the sound travel time across the shell, raising the possibility for an explosive outcome rather than an Eddington limited helium novae. The nature of the explosion (i.e., deflagration or detonation) remains ambiguous, is certainly density dependent, and likely breaks spherical symmetry. In the case of detonation, this causes a laterally propagating front whose properties in these geometrically thin and low-density shells we begin to study here. Our calculations show that the radial expansion time of <0.1 s leads to incomplete helium burning, in agreement with recent work by Sim and collaborators, but that the nuclear energy released is still adequate to realize a self-sustaining laterally propagating detonation. These detonations are slower than the Chapman-Jouguet speed of 1.5 Multiplication-Sign 10{sup 9} cm s{sup -1}, but still fast enough at 0.9 Multiplication-Sign 10{sup 9} cm s{sup -1} to go around the star prior to the transit through the star of the inwardly propagating weak shock. Our simulations resolve the subsonic region behind the reaction front in the detonation wave. The two-dimensional nucleosynthesis is shown to be consistent with a truncated one-dimensional Zeldovich-von Neumann-Doering calculation at the slower detonation speed. The ashes from the lateral detonation are typically He rich, and consist of predominantly {sup 44}Ti, {sup 48}Cr, along with a small amount of {sup 52}Fe, with very little {sup 56}Ni and with significant {sup 40}Ca in carbon-enriched layers. If this helium detonation results in a Type Ia supernova, its spectral signatures would appear for the first few days after explosion.

Townsley, Dean M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487-0324 (United States); Moore, Kevin; Bildsten, Lars, E-mail: Dean.M.Townsley@ua.edu [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States)

2012-08-10T23:59:59.000Z

440

Extent of surface regions near corner points of notched cracked bodies subjected to mode-I loading  

Science Conference Proceedings (OSTI)

In the present paper, the extent of surface regions in cracked bodies subjected to mode-I loading was examined, which is important for a proper definition of finite element meshes. Different specimen geometries with and without lateral notches, representative ... Keywords: Crack shape evolution, Extent of surface region, Fatigue crack growth, Finite element method, Stress triaxiality

R. Branco; F. V. Antunes; L. C. H. Ricardo; J. D. Costa

2012-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Applying neural networks, genetic algorithms and fuzzy logic for the identification of cracks in shafts by using coupled response measurements  

Science Conference Proceedings (OSTI)

This paper considers the dynamic behavior of a shaft with two transverse cracks characterized by three measures: position, depth and relative angle. Both cracks are considered to lie along arbitrary angular positions with respect to the longitudinal ... Keywords: Coupling, Crack identification, Genetic algorithms, Neural networks, Shaft

K. M. Saridakis; A. C. Chasalevris; C. A. Papadopoulos; A. J. Dentsoras

2008-06-01T23:59:59.000Z

442

EMAT based inspection of natural gas pipelines for SSC cracks  

NLE Websites -- All DOE Office Websites (Extended Search)

EMAT-Based Inspection of Natural Gas EMAT-Based Inspection of Natural Gas Pipelines for Stress Corrosion Cracks FY2004 Report Venugopal K. Varma, Raymond W. Tucker, Jr., and Austin P. Albright Oak Ridge National Laboratory Oak Ridge, Tennessee 37831 1 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name,

443

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

2012-09-16T23:59:59.000Z

444

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

Tsoy, L A; Komarov, A G; Tsoy, A N

2012-01-01T23:59:59.000Z

445

CRACK GROWTH ANALYSIS OF SOLID OXIDE FUEL CELL ELECTROLYTES  

DOE Green Energy (OSTI)

Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis, and statistics are available and reasonably well developed. These design codes also incorporate material data such as elastic constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells. Rings cut from the tubes were characterized for microstructure, phase stability, mechanical strength (Weibull modulus) and fracture mechanisms. The strength at operating condition of SOFCs (1000 C) decreased to 95 MPa as compared to room temperature strength of 230 MPa. However, the Weibull modulus remains relatively unchanged. Slow crack growth (SCG) parameter, n = 17 evaluated at room temperature in air was representative of well studied brittle materials. Based on the results, further work was planned to evaluate the strength degradation, modulus and failure in more representative environment of the SOFCs.

S. Bandopadhyay; N. Nagabhushana

2003-10-01T23:59:59.000Z

446

Evaluation of the filler effects on fatique cracking and permanent deformation of asphalt concrete mixtures  

E-Print Network (OSTI)

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. The addition of hydrated lime produces a filler effect where the result is a stiffening of the asphalt mixture, thus improving the resistance to permanent deformation. The fatigue characteristics of the asphalt mixtures did not worsen from this stiffening effect, but were either improved or similar. The Superpave Performance Grade was not significantly indicative of the filler effects induced by the hydrated lime. However, evaluation of the physical properties, G*/sin5 and G*sin5 were indicative of significant filler effects induced by the hydrated lime. Creep properties, stiffness and m-value showed no substantial change with the addition of lime. The use of 10 to 20% mass concentration of hydrated lime can effectively improve the rutting resistance of the unaged and aged binder with little practical effect on the low temperature and fatigue properties. The filler effects produced through the addition of hydrated lime to the asphalt yielded asphalt mixtures less susceptible to rutting. In most cases, the fatigue life of the asphalt mixtures improved as well. The reference modulus and creep compliance of the asphalt mixtures with lime had shown to have greater fatigue life. In most cases, Stone Matrix Asphalt (SMA) mixtures with lime showed greater resistance to rutting, as well as greater fatigue life. The filler effects from the hydrated lime, as well as the stone-on-stone contact and stiffening from the mastic (two characteristics of SMA mixtures) improved these properties. The addition of hydrated lime to asphalt improved the G*/sin5 and G*sin8 of the asphalt binders. The use of these asphalt binders in asphalt concrete mixtures increased the resistance to rutting and fatigue life. It is apparent that a correlation exists between the asphalt binder and mixture test results.

Izzo, Richard P

1997-01-01T23:59:59.000Z

447

Effect of PCC Joint Skew on Reflective Cracking in HMA Overlays  

E-Print Network (OSTI)

Reflective cracking is a relatively premature distress that occurs in HMA materials overlaying cracked and jointed underlying pavements. The high concentration of stresses and strains in the vicinity of the discontinuity of the old pavement causes the cracks to reflect into the newly placed HMA overlay. While it is a common practice to use skewed transverse joints in rigid pavements to improve the latter's performance, the impact of such a practice on the cracking of a potential HMA overlay has not been examined so far. In this context, this study investigates the effect of using skewed transverse joints in rigid pavements on reflective cracking development in the HMA overlay. Advanced three-dimensional Finite Element models including viscoelastic material properties for the HMA overlay, 3D beam modeling of dowel bars, non-uniform tire-pavement contact stresses, friction interfaces, and infinite boundary elements were constructed for both normal and skewed transverse joints using ABAQUS v-6.11. The potential for reflective cracking was monitored through the fracture mechanics J-integral parameter. Results obtained show, among other things, that the practice of skewing transverse joints increases the potential for reflective cracking development in the asphalt concrete overlay.

Ziad G. Ghauch

2011-10-14T23:59:59.000Z

448

Crack Formation in the Presence of an Electric Field in Droplets of Laponite Gel  

E-Print Network (OSTI)

When a colloidal gel dries through evaporation, cracks are usually formed, which often reveal underlying processes at work during desiccation. Desiccating colloid droplets of few hundred $\\mu l$ size show interesting effects of pattern formation and cracking which makes this an active subject of current research. Since aqueous gels of clay are known to be strongly affected by an electric field, one may expect crack patterns to exhibit a field effect. In the present study we allow droplets of laponite gel to dry under a radial electric field. This gives rise to highly reproducible patterns of cracks, which depend on the strength, direction and time of exposure to the electric field. For a continuously applied DC voltage, cracks always appear on dissipation of a certain constant amount of energy. If the field is switched off before cracks appear, the observed results are shown to obey a number of empirical scaling relations, which enable us to predict the time of appearance and the number of cracks under specified conditions.

Tajkera Khatun; Tapati Dutta; Sujata Tarafdar

2013-08-14T23:59:59.000Z

449

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

Science Conference Proceedings (OSTI)

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.

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

2006-05-31T23:59:59.000Z

450

A heat exchanger between forced flow helium gas at 14 to 18 K and liquid hydrogen at 20 K circulated by natural convection  

E-Print Network (OSTI)

LBNL-53719 A HEAT EXCHANGER BETWEEN FORCED FLOW HELIUM GAShydrogen absorber and the heat exchanger between the liquidpasses through the heat exchanger in the absorber shell. The

Green, M.A.; Ishimoto, S.; Lau, W.; Yang, S.

2003-01-01T23:59:59.000Z

451

A passively-safe fusion reactor blanket with helium coolant and steel structure  

Science Conference Proceedings (OSTI)

Helium is attractive for use as a fusion blanket coolant for a number of reasons. It is neutronically and chemically inert, nonmagnetic, and will not change phase during any off-normal or accident condition. A significant disadvantage of helium, however, is its low density and volumetric heat capacity. This disadvantage manifests itself most clearly during undercooling accident conditions such as a loss of coolant accident (LOCA) or a loss of flow accident (LOFA). This thesis describes a new helium-cooled tritium breeding blanket concept which performs significantly better during such accidents than current designs. The proposed blanket uses reduced-activation ferritic steel as a structural material and is designed for neutron wall loads exceeding 4 MW/m{sup 2}. The proposed geometry is based on the nested-shell concept developed by Wong, but some novel features are used to reduce the severity of the first wall temperature excursion. These features include the following: (1) A ``beryllium-joint`` concept is introduced, which allows solid beryllium slabs to be used as a thermal conduction path from the first wall to the cooler portions of the blanket. The joint concept allows for significant swelling of the beryllium (10 percent or more) without developing large stresses in the blanket structure. (2) Natural circulation of the coolant in the water-cooled shield is used to maintain shield temperatures below 100 degrees C, thus maintaining a heat sink close to the blanket during the accident. This ensures the long-term passive safety of the blanket.

Crosswait, K.M.

1994-04-01T23:59:59.000Z

452

Microstructural damage produced by helium in aged /sup 238/PuO/sub 2/ fuels  

DOE Green Energy (OSTI)

Microstructural damage is produced in aged /sup 238/PuO/sub 2/ fuels used to power radioisotopic heat sources by the generation and release of the helium arising from alpha decay of the fuel. We obtained information about the nature and extent of this damage from metallographic examination of fuel pellets ranging in density from 87 to 94% with a grain size range of 6 to 30 ..mu..m that either were stored at ambient temperature for 18 months and then heated at 900, 1150, or 1360/sup 0/C or were stored at 900, 1150, or 1350/sup 0/C for 27 months. Microstructural damage was not observed in the fuel pellets stored at ambient temperature and then heated at 900/sup 0/C, but grain boundary bubble damage was observed in the pellets stored at ambient temperature and then heated at either 1150 or 1350/sup 0/C. More extensive damage occurred in those pellets heated at 1350/sup 0/C. Four of the higher density pellets (92 and 94% dense) stored at 900/sup 0/C shattered during storage and the rest appeared to be highly strained. The pellets stored at 1150/sup 0/C were damaged only slightly but were somewhat strained and appeared to have released their helium inventory only partially. All pellets stored at 1350/sup 0/C showed swelling and extensive void agglomeration. These data suggest that the best fuel operating temperature, as far as helium damage is concerned, would be approx. 1200/sup 0/C because below this temperature the fuel becomes highly strained and above this temperature the fuel swells ad becomes somewhat friable. Both these situations could adversely affect the impact behavior of the fuel from the standpoint of strength and fines generation.

Land, C.C.

1980-01-01T23:59:59.000Z

453

Theoretical study of sodium and potassium resonance lines pressure broadened by helium atoms  

SciTech Connect

We perform fully quantum mechanical calculations in the binary approximation of the emission and absorption profiles of the sodium 3s-3p and potassium 4s-4p resonance lines under the influence of a helium perturbing gas. We use carefully constructed potential energy surfaces and transition dipole moments to compute the emission and absorption coefficients at temperatures from 158 to 3000 K. Contributions from quasibound states are included. The resulting red and blue wing profiles agree well with previous theoretical calculations and with experimental measurements.

Zhu, Cheng; Babb, James F.; Dalgarno, Alex [ITAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)

2006-01-15T23:59:59.000Z

454

Theoretical study of pressure broadening of lithium resonance lines by helium atoms  

SciTech Connect

Quantum mechanical calculations are performed of the emission and absorption profiles of the lithium 2s-2p resonance line under the influence of a helium perturbing gas. We use carefully constructed potential energy surfaces and transition dipole moments to compute the emission and absorption coefficients at temperatures from 200 to 3000 K at wavelengths between 500 nm and 1000 nm. Contributions from quasibound states are included. The resulting red and blue wing profiles are compared with previous theoretical calculations and with an experiment, carried out at a temperature of 670 K.

Zhu Cheng; Babb, James F.; Dalgarno, Alex [ITAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)

2005-05-15T23:59:59.000Z

455

Operating experience with gas-bearing circulators in a high-pressure helium loop  

Science Conference Proceedings (OSTI)

A high-pressure engineering test loop has been designed and constructed at the Oak Ridge National Laboratory for circulating helium through a test chamber at temperatures to 1000/sup 0/C. The purpose of this loop is to determine the thermal and structural performance of proposed components for the primary loops of gas-cooled nuclear reactors. Five MW of power is available to provide the required gas temperature at the test chamber, and an air-cooled heat exchanger, rated at 4.4 MW, serves as a heat sink. This report contains results of tests performed on gas-bearing circulators.

Sanders, J.P.; Gat, Uri; Young, H.C.

1987-01-01T23:59:59.000Z

456

Low-energy scattering of antihydrogen by helium and molecular hydrogen  

SciTech Connect

In this paper, we describe in detail calculations that we have carried out of cross sections for rearrangement processes in very low-energy helium+antihydrogen (H-bar) scattering that result in He{sup +}p-bar+Ps or Hep-bar+e{sup +} or {alpha}p-bar+Ps{sup -}. The interaction between the leptons is taken into account very accurately. Results are presented for all three processes. A description is also given of a preliminary calculation of elastic and antiproton annihilation cross sections for very low-energy H{sub 2}+H-bar scattering.

Armour, E. A. G.; Todd, A. C.; Liu, Y.; Gregory, M. R. [School of Mathematical Sciences, Nottingham University, Nottingham NG7 2RD (United Kingdom); Jonsell, S. [Department of Physics, University of Wales Swansea, Swansea SA2 8PP (United Kingdom); Plummer, M. [CLRC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom)

2008-08-08T23:59:59.000Z

457

Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector  

E-Print Network (OSTI)

We analyze accumulation of ultracold neutrons (UCN) in a superfluid-helium converter vessel surrounded by a magnetic multipole reflector. Employing formulas valid for trapped UCN in mechanical equilibrium we solved the rate equation and obtained results for the saturation density of low field seeking UCN for any field strength of the multipolar field. The addition of magnetic storage can increase the density and energy of the UCN produced and serves to mitigate the effects of wall losses on the source performance. This work was performed in preparation of the UCN source project SuperSUN at the ILL.

O. Zimmer; R. Golub

2013-03-08T23:59:59.000Z

458

Deep Burn Develpment of Transuranic Fuel for High-Temperature Helium-Cooled Reactors - July 2010  

SciTech Connect

The DB Program Quarterly Progress Report for April - June 2010, ORNL/TM/2010/140, was distributed to program participants on August 4. This report discusses the following: (1) TRU (transuranic elements) HTR (high temperature helium-cooled reactor) Fuel Modeling - (a) Thermochemical Modeling, (b) 5.3 Radiation Damage and Properties; (2) TRU HTR Fuel Qualification - (a) TRU Kernel Development, (b) Coating Development, (c) ZrC Properties and Handbook; and (3) HTR Fuel Recycle - (a) Recycle Processes, (b) Graphite Recycle, (c) Pyrochemical Reprocessing - METROX (metal recovery from oxide fuel) Process Development.

Snead, Lance Lewis [ORNL; Besmann, Theodore M [ORNL; Collins, Emory D [ORNL; Bell, Gary L [ORNL

2010-08-01T23:59:59.000Z

459

Decoding sequential vs non-sequential two-photon double ionizationof helium using nuclear recoil  

SciTech Connect

Above 54.4 eV, two-photon double ionization of helium isdominated by a sequential absorption process, producing characteristicbehavior in the single and triple differential cross sections. We showthat the signature of this process is visible in the nuclear recoil crosssection, integrated over all energy sharings of the ejected electrons,even below the threshold for the sequential process. Since nuclear recoilmomentum imaging does not require coincident photoelectron measurement,the predicted images present a viable target for future experiments withnew short-pulse VUV and soft X-ray sources.

Horner, Daniel A.; Rescigno, Thomas N.; McCurdy, C. William

2008-01-07T23:59:59.000Z

460

Triple Differential Cross sections and Nuclear Recoil in Two-Photon Double Ionization of Helium  

SciTech Connect

Triple differential cross sections (TDCS) for two-photon double ionization of helium are calculated using the method of exterior complex scaling both above and below the threshold for sequential ionization (54.4 eV). It is found that sequential ionization produces characteristic behavior in the TDCS that identifies that process when it is in competition with nonsequential ionization. Moreover we see the signature in the TDCS and nuclear recoil cross sections of"virtual sequential ionization" below the threshold for the sequential process.

Horner, Daniel A.; McCurdy, C. William; Rescigno, Thomas N

2008-04-29T23:59:59.000Z

Note: This page contains sample records for the topic "helium induced cracking" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


461

Main features of direct cycle helium gas turbines integrated with a high temperature reactor  

SciTech Connect

From international nuclear industries fair; Basel, Switzerland (16 Oct 1972). The main features and advantages of direct cycle helium gas turbines integrated with a high temperature reactor are presented. The proposed design concept is based on a logical extension of existirg knowledge and experience on currently built gas cooled reactors and industrial gas turbines. The direct cycle gas turbine offers many advantages in the form of high reliability, safety and simplicity; it emerges as a potential competitor to the main power generation prime mover, the steam turbine. (auth)

Burylo, P.

1972-01-01T23:59:59.000Z

462

Cryogenic design of the liquid helium experiment ``critical dynamics in microgravity``  

Science Conference Proceedings (OSTI)

Although many well controlled experiments have been conducted to measure the static properties of systems near criticality, few experiments have explored the transport properties in systems driven far away from equilibrium as a phase transition occurs. The cryogenic design of an experiment to study the dynamic aspect of critical phenomena is reported here. Measurements of the thermal gradient across the superfluid (He II) -- normal fluid (He I) interface in helium under microgravity conditions will be performed as a heat flux holds the system away from equilibrium. New technologies are under development for this experiment, which is in the definition phase for a space shuttle flight.

Moeur, W.A. [New Mexico Univ., Albuquerque, NM (United States); Adriaans, M.J.; Boyd, S.T. [Sandia National Labs., Albuquerque, NM (United States); Strayer, D.M. [Jet Propulsion Lab., Pasadena, CA (United States); Duncan, R.V. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States)

1995-10-01T23:59:59.000Z

463

A helium-cooled blanket design of the low aspect ratio reactor  

Science Conference Proceedings (OSTI)

An aggressive low aspect ratio scoping fusion reactor design indicated that a 2 GW(e) reactor can have a major radius as small as 2.9 m resulting in a device with competitive cost of electricity at 49 mill/kWh. One of the technology requirements of this design is a high performance high power density first wall and blanket system. A 15 MPa helium-cooled, V-alloy and stagnant LiPb breeder first wall and blanket design was utilized. Due to the low solubility of tritium in LiPb, there is the concern of tritium migration and the formation of V-hydride. To address these issues, a lithium breeder system with high solubility of tritium has been evaluated. Due to the reduction of blanket energy multiplication to 1.2, to maintain a plant Q of > 4, the major radius of the reactor has to be increased to 3.05 m. The inlet helium coolant temperature is raised to 436 C in order to meet the minimum V-alloy temperature limit everywhere in the first wall and blanket system. To enhance the first wall heat transfer, a swirl tape coolant channel design is used. The corresponding increase in friction factor is also taken into consideration. To reduce the coolant system pressure drop, the helium pressure is increased from 15 to 18 MPa. Thermal structural analysis is performed for a simple tube design. With an inside tube diameter of 1 cm and a wall thickness of 1.5 mm, the lithium breeder can remove an average heat flux and neutron wall loading of 2 and 8 MW/m(2), respectively. This reference design can meet all the temperature and material structural design limits, as well as the coolant velocity limits. Maintaining an outlet coolant temperature of 650 C, one can expect a gross closed cycle gas turbine thermal efficiency of 45%. This study further supports the use of helium coolant for high power density reactor design. When used with the low aspect ratio reactor concept a competitive fusion reactor can be projected at 51.9 mill/kWh.

Wong, C.P.; Baxi, C.B.; Reis, E.E. [General Atomics, San Diego, CA (United States); Cerbone, R.; Cheng, E.T. [TSI Research, Solana Beach, CA (United States)

1998-03-01T23:59:59.000Z

464

Primordial Helium Abundance from CMB: a constraint from recent observations and a forecast  

E-Print Network (OSTI)

We study a constraint on the primordial helium abundance $Y_p$ from current and future observations of CMB. Using the currently available data from WMAP, ACBAR, CBI and BOOMERANG, we obtained the constraint as $Y_p = 0.25 \\pm 0.10$ at 1$\\sigma$ level. We also provide a forecast for Planck using the Markov Chain Monte Carlo approach. In addition to forecasting the constraint on $Y_p$, we investigate how assumptions for $Y_p$ affect the constraints on the other cosmological parameters.

Ichikawa, Kazuhide; Takahashi, Tomo

2007-01-01T23:59:59.000Z

465

Primordial Helium Abundance from CMB: a constraint from recent observations and a forecast  

E-Print Network (OSTI)

We studied a constraint on the primordial helium abundance Y_p from current and future observations of CMB. Using the currently available data from WMAP, ACBAR, CBI and BOOMERANG, we obtained the constraint as Y_p = 0.25^{+0.10}_{-0.07} at 68% C.L. We also provide a forecast for the Planck experiment using the Markov chain Monte Carlo approach. In addition to forecasting the constraint on Y_p, we investigate how assumptions for Y_p affect constraints on the other cosmological parameters.

Kazuhide Ichikawa; Toyokazu Sekiguchi; Tomo Takahashi

2007-12-28T23:59:59.000Z

466

High-energy electron-helium scattering in a Nd:YAG laser field  

SciTech Connect

We report measurements of the scattering of electrons by helium atoms in the presence of 1.17 eV photons from a Nd:YAG laser. The incident energy of the electrons was in the range 50-350 eV, and the polarization of the laser was arranged to be parallel to electrons scattered through 135 deg. Energy-shifted peaks corresponding both to one- and two-photon emission were observed. Calculations using the Kroll-Watson approximation are perfectly consistent with the data.

Harak, B. A. de [Physics Department, Illinois Wesleyan University, P.O. Box 2900, Bloomington, Illinois 61702-2900 (United States); Ladino, L.; MacAdam, K. B.; Martin, N. L. S. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)

2011-02-15T23:59:59.000Z

467

Studies on the disbonding initiation of interfacial cracks.  

SciTech Connect

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.<