WorldWideScience

Sample records for graphite sublimation tests

  1. Modelling of pulsed electron beam induced graphite ablation: Sublimation versus melting

    Science.gov (United States)

    Ali, Muddassir; Henda, Redhouane

    2017-12-01

    Pulsed electron beam ablation (PEBA) has recently emerged as a very promising technique for the deposition of thin films with superior properties. Interaction of the pulsed electron beam with the target material is a complex process, which consists of heating, phase transition, and erosion of a small portion from the target surface. Ablation can be significantly affected by the nature of thermal phenomena taking place at the target surface, with subsequent bearing on the properties, stoichiometry and structure of deposited thin films. A two stage, one-dimensional heat conduction model is presented to describe two different thermal phenomena accounting for interaction of a graphite target with a polyenergetic electron beam. In the first instance, the thermal phenomena are comprised of heating, melting and vaporization of the target surface, while in the second instance the thermal phenomena are described in terms of heating and sublimation of the graphite surface. In this work, the electron beam delivers intense electron pulses of ∼100 ns with energies up to 16 keV and an electric current of ∼400 A to a graphite target. The temperature distribution, surface recession velocity, ablated mass per unit area, and ablation depth for the graphite target are numerically simulated by the finite element method for each case. Based on calculation findings and available experimental data, ablation appears to occur mainly in the regime of melting and vaporization from the surface.

  2. Sublimator Driven Coldplate Engineering Development Unit Test Results

    Science.gov (United States)

    Sheth, Rubik B.; Stephan, Ryan A.; Leimkuehler, Thomas O.

    2010-01-01

    The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially increasing reliability and reducing complexity while saving both mass and power. Because the SDC requires a consumable feedwater, it can only be used for short mission durations. Additionally, the SDC is ideal for a vehicle with small transport distances and low heat rejection requirements. An SDC Engineering Development Unit was designed and fabricated. Performance tests were performed in a vacuum chamber to quantify and assess the performance of the SDC. The test data was then used to develop correlated thermal math models. Nonetheless, an Integrated Sublimator Driven Coldplate (ISDC) concept is being developed. The ISDC couples a coolant loop with the previously described SDC hardware. This combination allows the SDC to be used as a traditional coldplate during long mission phases and provides for dissimilar system redundancy

  3. Thermal shock test of TiC and graphite

    International Nuclear Information System (INIS)

    Shirakawa, H.; Okamura, J.; Son, P.; Miyake, M.

    1989-01-01

    Thermal shock tests were performed by pulse electron beam heating on chemically vapor deposited coatings of TiC on Poco graphite, bulk TiC, and several kinds of isotropic graphite. The specimens were heated at various power densities (10-45 MW/m 2 ) for various pulse durations (1-2 s) to examine the dependence of thermal failures on heating conditions. The TiC coating on graphite suffered cracking, surface melting and evaporation by the thermal pulse. The surface melting limit, defined as F τ 1/2 , where F is the minimum power density that causes surface melting for a specified pulse duration τ, was approximately 48 MWs 1/2 /m 2 for the TiC coating. The combined-Carbon/Titanium ratio of the coating after electron beam heating decreased with increasing power density and pulse duration. The bulk TiC specimens were so brittle that they fractured at heat load conditions where the coating showed no damage. The graphite specimens showed sublimation as a principal damage mechanism by the thermal pulse, and the sublimation weight loss decreased with increasing the thermal conductivity of the specimen. It was confirmed that the TiC coating on graphite had favorable resistance to thermal shock as compared to the bulk TiC and that graphite with high thermal conductivity is promising material as a high heat flux component. (orig.)

  4. Deposition of polycrystalline Cd{sub 1-x}Zn{sub x} Te films on ZnTe/graphite and graphite substrates by close-spaced sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Tamotsu; Akiba, Sho; Takahashi, Kohei; Nagatsuka, Satsuki; Kanda, Yohei [Department of Electrical and Electronic Engineering, Kisarazu National College of Technology, 2-11-1 Kiyomidai-higashi, Kisarazu, Chiba 292-0041 (Japan); Tokuda, Satoshi; Kishihara, Hiroyuki; Sato, Toshiyuki [Technology Research Laboratory, Shimadzu Corporation, 3-9-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan)

    2014-07-15

    The effects of a ZnTe layer on the deposition of a Cd{sub 1-x}Zn{sub x}Te (CZT) layer in the initial stage of the close-spaced sublimation (CSS) deposition were investigated. The deposition rate was almost constant in the initial stage of the CdTe deposition on the ZnTe/graphite substrates. However, the deposition rate within 1 minute was lower than that after 1 minute in the CdTe deposition on graphite substrates. This result suggests that nucleation of CdTe directly deposited on graphite substrate is difficult when compared to that with a ZnTe layer. Furthermore, the effects of CdCl{sub 2} and ZnTe additions to the CdTe sources in the CSS deposition were also investigated. Both the grain size and the intensity of donor-acceptor pair (DAP) emission in photoluminescence (PL) spectra were decreased by the effect of CdCl{sub 2} addition. Zn content in CZT films was controlled by the ZnTe ratio in the CdTe/ZnTe powder sources. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. High temperature tests for graphite materials

    OpenAIRE

    Zhmurikov, Evgenij

    2015-01-01

    This study was performed within the framework of the EURISOL for facilities SPIRAL-II (GANIL, France) and SPES (LNL, Italy), and aims to investigate the anticipated strength properties of fine-grained graphite at elevated temperatures. It appears that the major parameters that affect to the lifetime of a graphite target of this IP are the temperature and heating time. High temperature tests were conducted to simulate the heating under the influence of a beam of heavy particles by passing thro...

  6. Sublimator Driven Coldplate Engineering Development Unit Test Results and Development of Second Generation SDC

    Science.gov (United States)

    Stephan, Ryan A.; Sheth, Rubik B.

    2009-01-01

    The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially increasing reliability and reducing complexity while saving both mass and power. Furthermore, the Integrated Sublimator Driven Coldplate (ISDC) concept couples a coolant loop with the previously described SDC hardware. This combination allows the SDC to be used as a traditional coldplate during long mission phases. The previously developed SDC technology cannot be used for long mission phases due to the fact that it requires a consumable feedwater for heat rejection. Adding a coolant loop also provides for dissimilar redundancy on the Altair Lander ascent module thermal control system, which is the target application for this technology. Tests were performed on an Engineering Development Unit at NASA s Johnson Space Center to quantify and assess the performance of the SDC. Correlated thermal math models were developed to help explain the test data. The paper also outlines the preliminary results of an ISDC concept being developed.

  7. Acceptance test for graphite components and construction status of HTTR

    International Nuclear Information System (INIS)

    Iyoku, T.; Ishihara, M.; Maruyama, S.; Shiozawa, S.; Tsuji, N.; Miki, T.

    1996-01-01

    In March, 1991, the Japan Atomic Energy Research Institute (JAERI) started to constructed the High Temperature engineering Test Reactor(HTTR) which is a 30-MW(thermal) helium gas-cooled reactor with a core composed of prismatic graphite blocks piled on the core support graphite structures. Two types of graphite materials are used in the HTTR. One is the garde IG-110, isotropic fine grain graphite, another is the grade PGX, medium-to-fine grained molded graphite. These materials were selected on the basis of the appropriate properties required by the HTTR reactor design. Industry-wide standards for an acceptance test of graphite materials used as main components of a nuclear reactor had not been established. The acceptance standard for graphite components of the HTTR, therefore, was drafted by JAERI and reviewed by specialists outside JAERI. The acceptance standard consists of the material testing, non-destructive examination such as the ultrasonic and eddy current testings, dimensional and visual inspections and assembly test. Ultrasonic and eddy current testings are applied to graphite logs to detect an internal flaw and to graphite components to detect a surface flaw, respectively. The assembly test is performed at the works, prior to their installation in the reactor pressure vessel, to examine fabricating precision of each component and alignment of piled-up structures. The graphite components of the HTTR had been tested on the basis of the acceptance standard. It was confirmed that the graphite manufacturing process was well controlled and high quality graphite components were provided to the HTTR. All graphite components except for the fuel graphite blocks are to be installed in the reactor pressure vessel of the HTTR in September 1995. The paper describes the construction status of the HTTR focusing on the graphite components. The acceptance test results are also presented in this paper. (author). Figs

  8. On Sublimation.

    Science.gov (United States)

    Civitarese, Giuseppe

    2016-10-01

    Although it encapsulates the Freudian theory of art, the theory of sublimation has become outmoded. What is more, since its inception there has always been something ill-defined about it. Does it use sexualized or de-sexualized drive energy? Is it a defence or an alternative to defence? Does it serve Eros or Thanatos? Is it useful in clinical work or is it unusable? The only, albeit uncertain, aid to a definition relies on the extrinsic criterion of concrete artistic realization. My aim here to revisit and possibly 'reinvent' sublimation in the light of certain principles of the pre-Romantic aesthetics of the sublime. Both are theories of spiritual elevation, in other words, elevation that moves towards abstract thinking, and of man's 'moral' achievement; and both attempt to explain the mystery of aesthetic experience. On the one hand, the aesthetics of the sublime offers a modern myth that helps us articulate a series of factors occasionally referred to by various authors as constitutive of sublimation but which have not been incorporated into a single organic framework: loss and early mourning work; the earlier existence of a catastrophic factor - to be regarded, depending on the situation, as either traumatic or simply 'negative'; the correspondence with a process of somatopsychic categorization which coincides with subjectivity. On the other hand, it also helps us grasp the experience of negative pleasure empathically, living it 'from the inside'. Copyright © 2016 Institute of Psychoanalysis.

  9. Graphite selection for the FMIT test cell

    International Nuclear Information System (INIS)

    Morgan, W.C.

    1982-06-01

    This document provides the basis for procuring a grade of graphite, at minimum cost, having minimum dimensional changes at low irradiation temperatures (nominal range 90 to 140 0 C). In light of those constraints, the author concludes that the most feasible approach is to attempt to reproduce a grade of graphite (TSGBF) which has exhibited a high degree of dimensional stability during low-temperature irradiations and on which irradiation-induced changes in other physical properties have been measured. The effects of differences in raw materials, especially coke morphology, and processing conditions, primarily graphitization temperture are briefly reviewed in terms of the practicality of producing a new grade of graphite with physical properties and irradiation-induced changes which would be very similar to those of TSGBF graphite. The production history and physical properties of TSGBF are also reviewed; no attempt is made, to project changes in dimensions or physical properties under the projected irradiation conditions

  10. Graphite

    Science.gov (United States)

    Robinson, Gilpin R.; Hammarstrom, Jane M.; Olson, Donald W.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Graphite is a form of pure carbon that normally occurs as black crystal flakes and masses. It has important properties, such as chemical inertness, thermal stability, high electrical conductivity, and lubricity (slipperiness) that make it suitable for many industrial applications, including electronics, lubricants, metallurgy, and steelmaking. For some of these uses, no suitable substitutes are available. Steelmaking and refractory applications in metallurgy use the largest amount of produced graphite; however, emerging technology uses in large-scale fuel cell, battery, and lightweight high-strength composite applications could substantially increase world demand for graphite.Graphite ores are classified as “amorphous” (microcrystalline), and “crystalline” (“flake” or “lump or chip”) based on the ore’s crystallinity, grain-size, and morphology. All graphite deposits mined today formed from metamorphism of carbonaceous sedimentary rocks, and the ore type is determined by the geologic setting. Thermally metamorphosed coal is the usual source of amorphous graphite. Disseminated crystalline flake graphite is mined from carbonaceous metamorphic rocks, and lump or chip graphite is mined from veins in high-grade metamorphic regions. Because graphite is chemically inert and nontoxic, the main environmental concerns associated with graphite mining are inhalation of fine-grained dusts, including silicate and sulfide mineral particles, and hydrocarbon vapors produced during the mining and processing of ore. Synthetic graphite is manufactured from hydrocarbon sources using high-temperature heat treatment, and it is more expensive to produce than natural graphite.Production of natural graphite is dominated by China, India, and Brazil, which export graphite worldwide. China provides approximately 67 percent of worldwide output of natural graphite, and, as the dominant exporter, has the ability to set world prices. China has significant graphite reserves, and

  11. Development of fracture toughness test method for nuclear grade graphite

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C. H.; Lee, J. S.; Cho, H. C.; Kim, D. J.; Lee, D. J. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2006-02-15

    Because of its high strength and stability at very high temperature, as well as very low thermal neutron absorption cross-section, graphite has been widely used as a structural material in Gas Cooled Reactors (GCR). Recently, many countries are developing the Very High Temperature gas cooled Reactor (VHTR) because of the potentials of hydrogen production, as well as its safety and viable economics. In VHTR, helium gas serves as the primary coolant. Graphite will be used as a reflector, moderator and core structural materials. The life time of graphite is determined from dimensional changes due to neutron irradiation, which closely relates to the changes of crystal structure. The changes of both lattice parameter and crystallite size can be easily measured by X-ray diffraction method. However, due to high cost and long time of neutron irradiation test, ion irradiation test is being performed instead in KAERI. Therefore, it is essential to develop the technique for measurement of ion irradiation damage of nuclear graphite. Fracture toughness of nuclear grade graphite is one of the key properties in the design and development of VHTR. It is important not only to evaluate the various properties of candidate graphite but also to assess the integrity of nuclear grade graphite during operation. Although fracture toughness tests on graphite have been performed in many laboratories, there have been wide variations in values of the calculated fracture toughness, due to the differences in the geometry of specimens and test conditions. Hence, standard test method for nuclear graphite is required to obtain the reliable fracture toughness values. Crack growth behavior of nuclear grade graphite shows rising R-curve which means the increase in crack growth resistance as the crack length increases. Crack bridging and microcracking have been proposed to be the dominant mechanisms of rising R-curve behavior. In this paper, the technique to measure the changes of crystallite size and

  12. Fracture toughness testing of a reactor grade graphite

    Energy Technology Data Exchange (ETDEWEB)

    Roeding, M.; Klein, G.; Schiffers, H.; Nickel, H.

    1976-03-15

    Fracture mechanics is a well established tool for the assessment of brittle fracture in metallic structural materials. In this paper an attempt is made to apply fracture mechanics to a reactor-grade graphite. The effect of several test parameters on the stress intensity factor was measured; this was found to lie in the range 25 and 50 N/mm/sup -3/2/. The results are discussed in terms of the well known mechanical characteristics of graphite.

  13. Nondestructive testing on graphite structures for high temperature engineering test reactor (HTTR)

    International Nuclear Information System (INIS)

    Ishihara, Masahiro; Kambe, Mamoru; Tsuji, Nobumasa.

    1994-01-01

    The application of ultrasonic (for internal defects) and eddy current testing (for surface defects) were investigated on the structures of nuclear-grade IG-110 and PGX graphite for the HTTR. The equipment were developed in order to detect the specific configuration of graphite blocks and the testing conditions were defined as the practical testing methods. The established testing methods are being used for the acceptance tests of graphite structures in the HTTR. (author)

  14. Testing of Small Graphite Samples for Nuclear Qualification

    Energy Technology Data Exchange (ETDEWEB)

    Julie Chapman

    2010-11-01

    Accurately determining the mechanical properties of small irradiated samples is crucial to predicting the behavior of the overal irradiated graphite components within a Very High Temperature Reactor. The sample size allowed in a material test reactor, however, is limited, and this poses some difficulties with respect to mechanical testing. In the case of graphite with a larger grain size, a small sample may exhibit characteristics not representative of the bulk material, leading to inaccuracies in the data. A study to determine a potential size effect on the tensile strength was pursued under the Next Generation Nuclear Plant program. It focuses first on optimizing the tensile testing procedure identified in the American Society for Testing and Materials (ASTM) Standard C 781-08. Once the testing procedure was verified, a size effect was assessed by gradually reducing the diameter of the specimens. By monitoring the material response, a size effect was successfully identified.

  15. Progress in Developing Finite Element Models Replicating Flexural Graphite Testing

    International Nuclear Information System (INIS)

    Bratton, Robert

    2010-01-01

    This report documents the status of flexural strength evaluations from current ASTM procedures and of developing finite element models predicting the probability of failure. This work is covered under QLD REC-00030. Flexural testing procedures of the American Society for Testing and Materials (ASTM) assume a linear elastic material that has the same moduli for tension and compression. Contrary to this assumption, graphite is known to have different moduli for tension and compression. A finite element model was developed and demonstrated that accounts for the difference in moduli tension and compression. Brittle materials such as graphite exhibit significant scatter in tensile strength, so probabilistic design approaches must be used when designing components fabricated from brittle materials. ASTM procedures predicting probability of failure in ceramics were compared to methods from the current version of the ASME graphite core components rules predicting probability of failure. Using the ASTM procedures yields failure curves at lower applied forces than the ASME rules. A journal paper was published in the Journal of Nuclear Engineering and Design exploring the statistical models of fracture in graphite.

  16. Project accent: graphite irradiated creep in a materials test reactor

    International Nuclear Information System (INIS)

    Brooking, M.

    2014-01-01

    Atkins manages a pioneering programme of irradiation experiments for EDF Energy. One of these projects is Project ACCENT, designed to obtain evidence of a beneficial physical property of the graphite, which may extend the life of the Advanced Gas-cooled Reactors (AGRs). The project team combines the in-house experience of EDF Energy with two supplier organisations (providing the material test reactors and testing facilities) and supporting consultancies (Atkins and an independent technical expert). This paper describes: - Brief summary of the Project; - Discussion of the challenges faced by the Project; and - Conclusion elaborating on the aims of the Project. These challenging experiments use bespoke technology and both un-irradiated (virgin) and irradiated AGR graphite. The results will help to better understand graphite irradiation-induced creep (or stress modified dimensional change) properties and therefore more accurately determine lifetime and safe operating envelopes of the AGRs. The first round of irradiation has been completed, with a second round about to commence. This is a key step to realising the full lifetime ambition for AGRs, demonstrating the relaxation of stresses within the graphite bricks. (authors)

  17. Study on practical of eddy current testing of core and core support graphite components in HTTR

    International Nuclear Information System (INIS)

    Ishihara, Masahiro; Iyoku, Tatsuo; Ooka, Norikazu; Shindo, Yoshihisa; Kawae, Hidetoshi; Hayashi, Motomitsu; Kambe, Mamoru; Takahashi, Masaaki; Ide, Akira.

    1994-01-01

    Core and core support graphite components in the HTTR (High Temperature Engineering Test Reactor) are mainly made of nuclear-grade IG-110 and PGX graphites. Nondestructive inspection with Eddy Current Testing (ECT) is planned to be applied to these components. The method of ECT has been already established for metallic components, however, cannot be applied directly to the graphite ones, because the characteristics of graphite are quite different in micro-structure from those of metals. Therefore, ECT method and condition were studied for the application of the ECT to the graphite components. This paper describes the study on practical method and conditions of ECT for above mentioned graphite structures. (author)

  18. Eddy current testing on structures of nuclear-grade IG-110 graphite for acceptance test in HTTR

    International Nuclear Information System (INIS)

    Ishihara, Masahiro; Saikusa, Akio; Iyoku, Tatsuo

    1993-09-01

    Core and core support graphite structures in the HTTR are mainly made of IG-110 graphite which is fine-grained isotropic and nuclear-grade. Nondestructive inspection with eddy current testing is planned to be applied to these graphite structures. Eddy current testing is widely applied to metallic structures and its testing method has been already established. On the other hand, the characteristics of graphite are quite different in micro-structure from these of metals. Therefore, the eddy current testing method provided for metallic structures can not be applied directly to graphite structures. Thus the eddy current testing method and condition were established for the graphite structures made of IG-110 graphite. (author)

  19. Instant Sublime Text starter

    CERN Document Server

    Haughee, Eric

    2013-01-01

    A starter which teaches the basic tasks to be performed with Sublime Text with the necessary practical examples and screenshots. This book requires only basic knowledge of the Internet and basic familiarity with any one of the three major operating systems, Windows, Linux, or Mac OS X. However, as Sublime Text 2 is primarily a text editor for writing software, many of the topics discussed will be specifically relevant to software development. That being said, the Sublime Text 2 Starter is also suitable for someone without a programming background who may be looking to learn one of the tools of

  20. Final report on graphite irradiation test OG-2

    International Nuclear Information System (INIS)

    Price, R.J.; Beavan, L.A.

    1975-01-01

    Results are presented of dimensional, thermal expansivity, thermal conductivity, Young's modulus, and tensile strength measurements on specimens of nuclear graphites irradiated in capsule OG-2. About half the irradiation space was allocated to H-451 near-isotropic petroleum-coke-based graphite or its subsized prototype grade H-429. Most of these specimens had been previously irradiated. Virgin specimens of another near-isotropic graphite, grade TS-1240, were irradiated. Some previously irradiated specimens of needle-coke-based H-327 graphite and pitch-coke-based P 3 JHAN were also included

  1. Graphite electrode arc melter demonstration Phase 2 test results

    International Nuclear Information System (INIS)

    Soelberg, N.R.; Chambers, A.G.; Anderson, G.L.; O'Connor, W.K.; Oden, L.L.; Turner, P.C.

    1996-06-01

    Several U.S. Department of Energy organizations and the U.S. Bureau of Mines have been collaboratively conducting mixed waste treatment process demonstration testing on the near full-scale graphite electrode submerged arc melter system at the Bureau's Albany (Oregon) Research Center. An initial test series successfully demonstrated arc melter capability for treating surrogate incinerator ash of buried mixed wastes with soil. The conceptual treatment process for that test series assumed that buried waste would be retrieved and incinerated, and that the incinerator ash would be vitrified in an arc melter. This report presents results from a recently completed second series of tests, undertaken to determine the ability of the arc melter system to stably process a wide range of open-quotes as-receivedclose quotes heterogeneous solid mixed wastes containing high levels of organics, representative of the wastes buried and stored at the Idaho National Engineering Laboratory (INEL). The Phase 2 demonstration test results indicate that an arc melter system is capable of directly processing these wastes and could enable elimination of an up-front incineration step in the conceptual treatment process

  2. Graphite electrode arc melter demonstration Phase 2 test results

    Energy Technology Data Exchange (ETDEWEB)

    Soelberg, N.R.; Chambers, A.G.; Anderson, G.L.; O`Connor, W.K.; Oden, L.L.; Turner, P.C.

    1996-06-01

    Several U.S. Department of Energy organizations and the U.S. Bureau of Mines have been collaboratively conducting mixed waste treatment process demonstration testing on the near full-scale graphite electrode submerged arc melter system at the Bureau`s Albany (Oregon) Research Center. An initial test series successfully demonstrated arc melter capability for treating surrogate incinerator ash of buried mixed wastes with soil. The conceptual treatment process for that test series assumed that buried waste would be retrieved and incinerated, and that the incinerator ash would be vitrified in an arc melter. This report presents results from a recently completed second series of tests, undertaken to determine the ability of the arc melter system to stably process a wide range of {open_quotes}as-received{close_quotes} heterogeneous solid mixed wastes containing high levels of organics, representative of the wastes buried and stored at the Idaho National Engineering Laboratory (INEL). The Phase 2 demonstration test results indicate that an arc melter system is capable of directly processing these wastes and could enable elimination of an up-front incineration step in the conceptual treatment process.

  3. Graphite Isotope Ratio Method Development Report: Irradiation Test Demonstration of Uranium as a Low Fluence Indicator

    International Nuclear Information System (INIS)

    Reid, B.D.; Gerlach, D.C.; Love, E.F.; McNeece, J.P.; Livingston, J.V.; Greenwood, L.R.; Petersen, S.L.; Morgan, W.C.

    1999-01-01

    This report describes an irradiation test designed to investigate the suitability of uranium as a graphite isotope ratio method (GIRM) low fluence indicator. GIRM is a demonstrated concept that gives a graphite-moderated reactor's lifetime production based on measuring changes in the isotopic ratio of elements known to exist in trace quantities within reactor-grade graphite. Appendix I of this report provides a tutorial on the GIRM concept

  4. Fabrication and testing of fire resistant graphite composite panels

    Science.gov (United States)

    Roper, W. D.

    1986-01-01

    Eight different graphite composite panels were fabricated using four different resin matrices. The resin matrices included Hercules 71775, a blend of vinylpolystyrpyridine and bismaleimide, H795, a bismaleimide, Cycom 6162, a phenolic, and PSP 6022m, a polystyrylpyridine. Graphite panels were fabricated using fabric or unidirectional tape. Described are the processes for preparing these panels and some of their mechanical, thermal and flammability properties. Panel properties are compared with state-of-the-art epoxy fiberglass composite panels.

  5. Evaluation of Accelerated Graphitic Corrosion Test of Gray Cast Iron

    International Nuclear Information System (INIS)

    Kim, Jeong Hyeon; Hong, Jong Dae; Chang Heui; Na, Kyung Hwan; Lee, Jae Gon

    2011-01-01

    In operating nuclear power plants, gray cast iron is commonly used as materials for various non-safety system components including pipes in fire water system, valve bodies, bonnets, and pump castings. In such locations, operating condition does not require alloy steels with excellent mechanical properties. But, a few corrosion related degradation, or graphitic corrosion is frequently occurred to gray cast iron during the long-term operation in nuclear power plant. Graphitic corrosion is selective leaching of iron from gray cast iron, where iron gets removed and graphite grains remain intact. In U.S.A., one-time visual inspection and hardness measurement are required from regulatory body to detect the graphitic corrosion for the life extension evaluation of the operating nuclear power plant. In this study, experiments were conducted to make accelerated graphitic corrosion of gray cast iron using electrochemical method, and hardness was measured for the specimens to establish the correlation between degree of graphitic corrosion and surface hardness of gray cast iron

  6. Final report on graphite irradiation test OG-3

    International Nuclear Information System (INIS)

    Price, R.J.; Beavan, L.A.

    1977-01-01

    The results of dimensional, thermal expansivity, thermal conductivity, Young's modulus, and tensile strength measurements on graphite specimens irradiated in capsule OG-3 are presented. The graphite grades investigated included near-isotropic H-451 (three different preproduction lots), TS-1240, and SO818; needle coke H-327; and European coal tar pitch coke grades P 3 JHA 2 N, P 3 JHAN, and ASI2-500. Data were obtained in the temperature range 823 0 K to 1673 0 K. The peak fast neutron fluence in the experiment was 3 x 10 25 n/m 3 (E greater than 29 fJ)/sub HTGR/; the total accumulated fluence exceeded 9 x 10 25 n/m 2 on some H-451 specimens and 6 x 10 25 n/m 2 on some TS-1240 specimens. Irradiation-induced dimensional changes on H-451 graphite differed slightly from earlier predictions. For an irradiation temperature of about 1225 0 K, axial shrinkage rates at high fluences were somewhat higher than predicted, and the fluence at which radial expansion started (about 9 x 10 25 n/m 2 at 1275 0 K) was lower. TS-1240 graphite underwent smaller dimensional changes than H-451 graphite, while limited data on SO818 and ASI2-500 graphites showed similar behavior to H-451. P 3 JHAN and P 3 JHA 2 N graphites displayed anisotropic behavior with rapid axial shrinkage. Comparison of dimensional changes between specimens from three logs of H-451 and of TS-1240 graphites showed no significant log-to-log variations for H-451, and small but significant log-to-log variations for TS-1240. The thermal expansivity of the near-isotropic graphites irradiated at 865-1045 0 K first increased by 5 percent to 10 percent and then decreased. At higher irradiation temperatures the thermal expansivity decreased by up to 50 percent. Changes in thermal conductivity were consistent with previously established curves. Specimens which were successively irradiated at two different temperatures took on the saturation conductivity for the new temperature

  7. Application of ISRM testing methods to fracture toughness testing of graphite

    International Nuclear Information System (INIS)

    Hashida, T.; Fukasawa, T.; Takahashi, H.; Ishiyama, S.; Oku, T.

    1987-01-01

    Fracture toughness measurements of nuclear grade graphites, IG11 and PGX, were made by means of AE technique. Tests were conducted on edge-notched round bend bar, edge-notched short bar and round compact tension specimens. These round-shaped specimens used in this study have been proposed for standard fracture toughness tests of rock as a draft of testing standard of International Society for Rock Mechanics (ISRM). Taking the observed nonlinear deformation behavior into account, J-integral approach was utilized to determine the fracture toughness of the graphites. It is shown that the critical J integral determined by AE technique, J iAE , is independent of specimen geometry. Based on this experimental results, the fracture toughness K IC of the graphites was determined from the J iAE values. K IC value of IG11 was 1.04 MPa√m, and 0.77 MPa√m for PGX respectively. Furthermore, the specimen size effect of the fracture toughness determined by the J-integral/AE method is discussed. (author)

  8. Irradiation test plan of oxidation-resistant graphite in WWR-K Research Reactor

    International Nuclear Information System (INIS)

    Sumita, Junya; Shibata, Taiju; Sakaba, Nariaki; Osaki, Hirotaka; Kato, Hideki; Fujitsuka, Kunihiro; Muto, Takenori; Gizatulin, Shamil; Shaimerdenov, Asset; Dyussambayev, Daulet; Chakrov, Petr

    2014-01-01

    Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor (HTGR) which is a graphite-moderated and helium gas-cooled reactor. In the case of air ingress accident in HTGR, SiO_2 protective layer is formed on the surface of SiC layer in TRISO CFP and oxidation of SiC does not proceed and fission products are retained inside the fuel particle. A new safety concept for the HTGR, called Naturally Safe HTGR, has been recently proposed. To enhance the safety of Naturally Safe HTGR ultimately, it is expected that oxidation-resistant graphite is used for graphite components to prevent the TRISO CFPs and fuel compacts from failure. SiC coating is one of candidate methods for oxidation-resistant graphite. JAEA and four graphite companies launched R&Ds to develop the oxidation-resistant graphite and the International Science and Technology Center (ISTC) partner project with JAEA and INP was launched to investigate the irradiation effects on the oxidation-resistant graphite. To determine grades of the oxidation-resistant graphite which will be adopted as irradiation test, a preliminary oxidation test was carried out. This paper described the results of the preliminary oxidation test, the plan of out-of-pile test, irradiation test and post-irradiation test (PIE) of the oxidation-resistant graphite. The results of the preliminary oxidation test showed that the integrity of the oxidation resistant graphite was confirmed and that all of grades used in the preliminary test can be adopted as the irradiation test. Target irradiation temperature was determined to be 1473 (K) and neutron fluence was determined to be from 0.54 × 10"2"5through 1.4 × 10"2"5 (/m"2, E>0.18MeV). Weight change, oxidation rate, activation energy, surface condition, etc. will be evaluated in out-of-pile test and weight change, irradiation effect on oxidation rate and activation energy, surface condition, etc. will be evaluated in PIE. (author)

  9. Sublimation, culture, and creativity.

    Science.gov (United States)

    Kim, Emily; Zeppenfeld, Veronika; Cohen, Dov

    2013-10-01

    Combining insights from Freud and Weber, this article explores whether Protestants (vs. Catholics and Jews) are more likely to sublimate their taboo feelings and desires toward productive ends. In the Terman sample (Study 1), Protestant men and women who had sexual problems related to anxieties about taboos and depravity had greater creative accomplishments, as compared to those with sexual problems unrelated to such concerns and to those reporting no sexual problems. Two laboratory experiments (Studies 2 and 3) found that Protestants produced more creative artwork (sculptures, poems, collages, cartoon captions) when they were (a) primed with damnation-related words, (b) induced to feel unacceptable sexual desires, or (c) forced to suppress their anger. Activating anger or sexual attraction was not enough; it was the forbidden or suppressed nature of the emotion that gave the emotion its creative power. The studies provide possibly the first experimental evidence for sublimation and suggest a cultural psychological approach to defense mechanisms.

  10. An explication of the Graphite Structural Design Code of core components for the High Temperature Engineering Test Reactor

    International Nuclear Information System (INIS)

    Iyoku, Tatsuo; Ishihara, Masahiro; Toyota, Junji; Shiozawa, Shusaku

    1991-05-01

    The integrity evaluation of the core graphite components for the High Temperature Engineering Test Reactor (HTTR) will be carried out based upon the Graphite Structural Design Code for core components. In the application of this design code, it is necessary to make clear the basic concept to evaluate the integrity of core components of HTTR. Therefore, considering the detailed design of core graphite structures such as fuel graphite blocks, etc. of HTTR, this report explicates the design code in detail about the concepts of stress and fatigue limits, integrity evaluation method of oxidized graphite components and thermal irradiation stress analysis method etc. (author)

  11. Biaxial testing for nuclear grade graphite by ball on three balls assessment

    International Nuclear Information System (INIS)

    Mohd Reusmaazran Yusof; Yusof Abdullah

    2012-01-01

    Nuclear grade (high-purity) graphite for fuel element and moderator material in Advanced Gas Cooling Reactors (AGR) displays large scatter in strength and a non-linear stress-strain response from the damage accumulation. These responses can be characterized as quasi-brittle behaviour. Current assessments of fracture in core graphite components are based on the linear elastic approximation and thus represent a major assumption. The quasi-brittle behaviour gives challenge to assess the real nuclear graphite component. The selected test method would help to bridge the gap between microscale to macro-scale in real reactor component. The small scale tests presented here can contribute some statistical data to manifests the failure in real component. The evaluation and choice of different solution design of biaxial test will be discussed in this paper. The ball on-three ball test method was used for assessment test follows by numerous of analytical method. The results shown that biaxial strength of the EY9 grade graphite depends on the method used for evaluation. Some of the analytical methods use to calculate biaxial strength were found not to be valid and therefore should not be used to assess the mechanical properties of nuclear graphite. (author)

  12. Sublime Imperfections : Annotated Reading List

    NARCIS (Netherlands)

    Rutten, E.

    2016-01-01

    In this reading list, I share thoughts on scholars and journalists from which the Sublime Imperfections project takes its inspiration. The authors of the texts that I clustered ponder the nexus between the imperfect and the sublime, they rethink repair and breakdown, they critically interrogate and

  13. Modelling Sublimation of Carbon Dioxide

    Science.gov (United States)

    Winkel, Brian

    2012-01-01

    In this article, the author reports results in their efforts to model sublimation of carbon dioxide and the associated kinetics order and parameter estimation issues in their model. They have offered the reader two sets of data and several approaches to determine the rate of sublimation of a piece of solid dry ice. They presented several models…

  14. Los cuerpos sublimes

    Directory of Open Access Journals (Sweden)

    Juan Pablo Zangara

    2015-09-01

    Full Text Available La narración de crímenes en la prensa de masas y las pantallas parece constituir una versión contemporánea del magnetismo según Edgar Allan Poe. La estetización mediática (ya no la información de una serie reciente de feminicidios permite reconocer una cierta lógica de lo sublime como clave de la producción de noticias-mercancías. En su variante clásica, la ficción policial funciona como una matriz ideológica decisiva de la enunciación periodística.

  15. Interim results: fines recycle testing using the 4-inch diameter primary graphite burner

    International Nuclear Information System (INIS)

    Palmer, W.B.

    1975-05-01

    The results of twenty-two HTGR primary burner runs in which graphite fines were recycled pneumatically to the 4-inch diameter pilot-plant primary fluidized-bed burner are described. The result of the tests showed that zero fines accumulation can easily be achieved while operating at plant equivalent burn rates. (U.S.)

  16. Cooperative program for design, fabrication, and testing of graphite/epoxy composite helicopter shafting

    Science.gov (United States)

    Wright, C. C.; Baker, D. J.; Corvelli, N.; Thurston, L.; Clary, R.; Illg, W.

    1971-01-01

    The fabrication of UH-1 helicopter tail rotor drive shafts from graphite/epoxy composite materials is discussed. Procedures for eliminating wrinkles caused by lack of precure compaction are described. The development of the adhesive bond between aluminum end couplings and the composite tube is analyzed. Performance tests to validate the superiority of the composite materials are reported.

  17. Brazing graphite to graphite

    International Nuclear Information System (INIS)

    Peterson, G.R.

    1976-01-01

    Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of graphite

  18. Observations in the statistical analysis of NBG-18 nuclear graphite strength tests

    International Nuclear Information System (INIS)

    Hindley, Michael P.; Mitchell, Mark N.; Blaine, Deborah C.; Groenwold, Albert A.

    2012-01-01

    Highlights: ► Statistical analysis of NBG-18 nuclear graphite strength test. ► A Weibull distribution and normal distribution is tested for all data. ► A Bimodal distribution in the CS data is confirmed. ► The CS data set has the lowest variance. ► A Combined data set is formed and has Weibull distribution. - Abstract: The purpose of this paper is to report on the selection of a statistical distribution chosen to represent the experimental material strength of NBG-18 nuclear graphite. Three large sets of samples were tested during the material characterisation of the Pebble Bed Modular Reactor and Core Structure Ceramics materials. These sets of samples are tensile strength, flexural strength and compressive strength (CS) measurements. A relevant statistical fit is determined and the goodness of fit is also evaluated for each data set. The data sets are also normalised for ease of comparison, and combined into one representative data set. The validity of this approach is demonstrated. A second failure mode distribution is found on the CS test data. Identifying this failure mode supports the similar observations made in the past. The success of fitting the Weibull distribution through the normalised data sets allows us to improve the basis for the estimates of the variability. This could also imply that the variability on the graphite strength for the different strength measures is based on the same flaw distribution and thus a property of the material.

  19. Outgassing tests on graphites in temperature range 100-1600 degrees C

    International Nuclear Information System (INIS)

    Alessandrini, C.; Apicella, M.L.; Verdini, L.

    1993-01-01

    Graphite is a an interesting material for plasma-facing components in fusion experiments, mainly because of its low atomic number and excellent thermal properties. Nevertheless, it contains a large amount of gaseous impurities, which can be released by plasma-surface interactions and affect the purity of the deuterium-tritium plasma. To investigate the outgassing behaviour of graphites, CFC's and doped C composites, a facility was set up to perform outgassing tests on samples, as a function of temperature in the range between 100 and 1600 degrees C. The experimental apparatus, designed to work in UHV conditions, allows outgassing measurements by a quadrupole mass spectrometer (1-200 AMU) using two different methods. The test facility, the quadrupole calibration and preliminary quantitative outgassing measurements on SEP CARB N112 samples are described

  20. Special graphites; Graphites speciaux

    Energy Technology Data Exchange (ETDEWEB)

    Leveque, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    A large fraction of the work undertaken jointly by the Commissariat a l'Energie Atomique (CEA) and the Pechiney Company has been the improvement of the properties of nuclear pile graphite and the opening up of new fields of graphite application. New processes for the manufacture of carbons and special graphites have been developed: forged graphite, pyro-carbons, high density graphite agglomeration of graphite powders by cracking of natural gas, impervious graphites. The physical properties of these products and their reaction with various oxidising gases are described. The first irradiation results are also given. (authors) [French] Ameliorer les proprietes du graphite nucleaire pour empilements et ouvrir de nouveaux domaines d'application au graphite constituent une part importante de l'effort entrepris en commun par le Commissariat a l'Energie Atomique (CEA) et la compagnie PECHINEY. Des procedes nouveaux de fabrication de carbones et graphites speciaux ont ete mis au point: graphite forge, pyrocarbone, graphite de haute densite, agglomeration de poudres de graphite par craquage de gaz naturel, graphites impermeables. Les proprietes physiques de ces produits ainsi que leur reaction avec differents gaz oxydants sont decrites. Les premiers resultats d'irradiation sont aussi donnes. (auteurs)

  1. Safety evaluation for packaging (onsite) plutonium recycle test reactor graphite cask

    International Nuclear Information System (INIS)

    Romano, T.

    1997-01-01

    This safety evaluation for packaging (SEP) provides the evaluation necessary to demonstrate that the Plutonium Recycle Test Reactor (PRTR) Graphite Cask meets the requirements of WHC-CM-2-14, Hazardous Material Packaging and Shipping, for transfer of Type B, fissile, non-highway route controlled quantities of radioactive material within the 300 Area of the Hanford Site. The scope of this SEP includes risk, shieldling, criticality, and.tiedown analyses to demonstrate that onsite transportation safety requirements are satisfied. This SEP also establishes operational and maintenance guidelines to ensure that transport of the PRTR Graphite Cask is performed safely in accordance with WHC-CM-2-14. This SEP is valid until October 1, 1999. After this date, an update or upgrade to this document is required

  2. Safety evaluation for packaging (onsite) plutonium recycle test reactor graphite cask

    Energy Technology Data Exchange (ETDEWEB)

    Romano, T.

    1997-09-29

    This safety evaluation for packaging (SEP) provides the evaluation necessary to demonstrate that the Plutonium Recycle Test Reactor (PRTR) Graphite Cask meets the requirements of WHC-CM-2-14, Hazardous Material Packaging and Shipping, for transfer of Type B, fissile, non-highway route controlled quantities of radioactive material within the 300 Area of the Hanford Site. The scope of this SEP includes risk, shieldling, criticality, and.tiedown analyses to demonstrate that onsite transportation safety requirements are satisfied. This SEP also establishes operational and maintenance guidelines to ensure that transport of the PRTR Graphite Cask is performed safely in accordance with WHC-CM-2-14. This SEP is valid until October 1, 1999. After this date, an update or upgrade to this document is required.

  3. Basic data for surveillance test on core support graphite structures for the high temperature engineering test reactor (HTTR)

    International Nuclear Information System (INIS)

    Sumita, Junya; Shibata, Taiju; Kikuchi, Takayuki; Iyoku, Tatsuo; Fujimoto, Nozomu; Ishihara, Masahiro; Sawa, Kazuhiro

    2007-02-01

    Both of the visual inspection by a TV camera and the measurement of material properties by surveillance test on core support graphite structures are planned for the High Temperature Engineering Test Reactor (HTTR) to confirm their structural integrity and characteristics. The surveillance test is aimed to investigate the change of material properties by aging effects such as fast neutron irradiation and oxidation. The obtained data will be used not only for evaluating the structural integrity of the core support graphite structures of the HTTR but also for design of advanced Very High Temperature Reactor (VHTR) discussed at generation IV international forum. This report describes the initial material properties of surveillance specimens before installation and installed position of surveillance specimens in the HTTR. (author)

  4. Sublime Views and Beautiful Explanations

    DEFF Research Database (Denmark)

    Barry, Daved; Meisiek, Stefan; Hatch, Mary Jo

    To create a generative theory that provides beautiful explanations and sublime views requires both a crafts and an art approach to scientific theorizing. The search for generativity leads scholars to perform various theorizing moves between the confines of simple, yet eloquent beauty...

  5. Testing of a graphite based extinguishing powder for use on liquid metal fires

    International Nuclear Information System (INIS)

    Menzenhauer, P.; Ochs, G.; Peppler, W.

    1977-11-01

    A graphite based extinguishing powder, newly developed by a French firm for use on liquid metal fires has been tested on a sodium fire in a pan of 0.96 m 2 using 60 kg of sodium. The behaviour and extinguishing power are reported and compared with those of other materials tested in earlier experiments. The new powder has excellent efficiency in dealing with sodium pool fires. Application is simple. The amount required is more than an order magnitude less than that of currently available alternatives. The powder is not corrosive. (orig.) [de

  6. Standard Test Methods for Properties of Continuous Filament Carbon and Graphite Fiber Tows

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1999-01-01

    1.1 These test methods cover the preparation and tensile testing of resin-impregnated and consolidated test specimens made from continuous filament carbon and graphite yarns, rovings, and tows to determine their tensile properties. 1.2 These test methods also cover the determination of the density and mass per unit length of the yarn, roving, or tow to provide supplementary data for tensile property calculation. 1.3 These test methods include a procedure for sizing removal to provide the preferred desized fiber samples for density measurement. This procedure may also be used to determine the weight percent sizing. 1.4 These test methods include a procedure for determining the weight percent moisture adsorption of carbon or graphite fiber. 1.5 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of t...

  7. The Sublime in churches and mosques

    NARCIS (Netherlands)

    Doudouh, N.; van Ginderen, S.

    2012-01-01

    Fear gives us the ability to experience the sublime in various situations when we talk about the sublime in architecture.According to Edmund Burke what causes this fear on a person, is darkness and vastness. Can it be that places of worship have been built for the purpose of expressing the sublime?

  8. Sublime science: Teaching for scientific sublime experiences in middle school classrooms

    Science.gov (United States)

    Cavanaugh, Shane

    (approximately 50 students participated) and the other on ecology (24 students participated). Both units proved to be a success in terms of the learning that resulted and in the positive experiences of the students and myself as the teacher. In both cases, students were give a pre and post multiple-choice test that covered questions typical of those found on the state's achievement exam and the schools' regular tests covering weather and ecology. Both groups of students showed a significant increase in learning. In an attempt to gain an understanding of student experiences with this type of learning, surveys and interviews were administered. The units appear to have profoundly affected students' ideas of weather and ecology---many reporting to see these concepts in new, richer ways. The goal of teaching for scientific sublime experiences is not only content knowledge, but to transform students' understanding of the world. Based on student comments and observations of classroom discussions, I feel that I largely achieved my goal.

  9. Structural Testing of a Stitched/Resin Film Infused Graphite-Epoxy Wing Box

    Science.gov (United States)

    Jegley, Dawn C.; Bush, Harold G.

    2001-01-01

    The results of a series of tests conducted at the NASA Langley Research Center to evaluate the behavior of an all-composite full-scale wing box are presented. The wing box is representative of a section of a 220-passenger commercial transport aircraft wing box and was designed and constructed by The Boeing Company as part of the NASA Advanced Subsonics Technology (AST) program. The semi-span wing was fabricated from a graphite-epoxy material system with cover panels and spars held together using Kevlar stitches through the thickness. No mechanical fasteners were used to hold the stiffeners to the skin of the cover panels. Tests were conducted with and without low-speed impact damage, discrete source damage and repairs. Up-bending, down-bending and brake roll loading conditions were applied. The structure with non-visible impact damage carried 97% of Design Ultimate Load prior to failure through a lower cover panel access hole.

  10. Kinetic and diffusion evaporation of substances on sublimation in vacuum

    International Nuclear Information System (INIS)

    Martinson, I.G.

    2006-01-01

    Diffusion-kinetic model of sublimation of substances in vacuum determining fields of the evaporation according to temperature - kinetic and diffusion is performed. The model is experimentally confirmed in the tests with benzoic acid and naphthalene, by calculation of the rate of Zn, Co, V, W sublimation and the value of coefficient of evaporation α. The model provides an explanation for derivation of low values of evaporation coefficient α, to 10 -10 , for easy to fusible substances, and α=1 for substances with high temperature of fusion [ru

  11. Development of in-service inspection system for core support graphite structures in the high temperature engineering test reactor (HTTR)

    Energy Technology Data Exchange (ETDEWEB)

    Sumita, Junya; Hanawa, Satoshi; Kikuchi, Takayuki; Ishihara, Masahiro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    2003-03-01

    Visual inspection of core support graphite structures using TV camera as in-service inspection and measurement of material characteristics using surveillance test specimens are planned in the High Temperature Engineering Test Reactor (HTTR) to confirm structural integrity of the core support graphite structures. For the visual inspection, in-service inspection system developed from September 1996 to June 1998, and pre-service inspection using the system was carried out. As the result of the pre-service inspection, it was validated that high quality of visual inspection with TV camera can be carried out, and also structural integrity of the core support graphite structures at the initial stage of the HTTR operation was confirmed. (author)

  12. Enthalpies of sublimation of fullerenes by thermogravimetry

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Herrera, Melchor; Campos, Myriam; Torres, Luis Alfonso; Rojas, Aarón, E-mail: arojas@cinvestav.mx

    2015-12-20

    Graphical abstract: - Highlights: • Enthalpies of sublimation of fullerenes were measured by thermogravimetry. • Results of enthalpies of sublimation are comparable with data reported in literature. • Not previously reported enthalpy of sublimation of C{sub 78} is supplied in this work. • Enthalpies of sublimation show a strong dependence with the number of carbon atoms in the cluster. • Enthalpies of sublimation are congruent with dispersion forces ruling cohesion of solid fullerene. - Abstract: The enthalpies of sublimation of fullerenes, as measured in the interval of 810–1170 K by thermogravimetry and applying the Langmuir equation, are reported. The detailed experimental procedure and its application to fullerenes C{sub 60}, C{sub 70}, C{sub 76}, C{sub 78} and C{sub 84} are supplied. The accuracy and uncertainty associated with the experimental results of the enthalpy of sublimation of these fullerenes show that the reliability of the measurements is comparable to that of other indirect high-temperature methods. The results also indicate that the enthalpy of sublimation increases proportionally to the number of carbon atoms in the cluster but there is also a strong correlation between the enthalpy of sublimation and the polarizability of each fullerene.

  13. Schopenhauer, Nietzsche, and the Aesthetically Sublime

    Science.gov (United States)

    Vandenabeele, Bart

    2003-01-01

    Much has been written on the relationship between Arthur Schopenhauer and Friedrich Nietzsche. Much remains to be said, however, concerning their respective theories of the sublime. In this article, the author first argues against the traditional, dialectical view of Schopenhauer's theory of the sublime that stresses the crucial role the sublime…

  14. Sacred Space and Sublime Sacramental Piety

    DEFF Research Database (Denmark)

    Petersen, Nils Holger

    2012-01-01

    Analyses and Discussions of Mozart's Sacramental Litanies K. 125 and K. 243 in relation to the notions of the Sacred and the Sublime.......Analyses and Discussions of Mozart's Sacramental Litanies K. 125 and K. 243 in relation to the notions of the Sacred and the Sublime....

  15. Graphite materials testing in the ATR for lifetime management of Magnox reactors

    International Nuclear Information System (INIS)

    Grover, S.B.; Metcalfe, M.P.

    2002-01-01

    A major feature of the Magnox gas cooled reactor design is the graphite core, which acts as the moderator but also provides the physical structure for fuel, control rods, instrumentation and coolant gas channels. The lifetime of a graphite core is dependent upon two principal aging processes: irradiation damage and radiolytic oxidation. Irradiation damage from fast neutrons creates lattice defects leading to changes in physical and mechanical properties and the accumulation of stresses. Radiolytic oxidation is caused by the reaction of oxidizing species from the carbon dioxide coolant gas with the graphite, these species being produced by gamma radiation. Radiolytic oxidation reduces the density and hence the moderating capability of the graphite, but also reduces strength affecting the integrity of core components. In order to manage continued operation over the planned lifetimes of their power stations, BNFL needed to extend their database of the effects of these two phenomena on their graphite cores through an irradiation experiment. This paper will discuss the background, purpose, and the processes taken and planned (i.e. post irradiation examination) to ensure meaningful data on the graphite core material is obtained from the irradiation experiment. (author)

  16. Graphite Materials Testing in the ATR for Lifetime Management of Magnox Reactors

    International Nuclear Information System (INIS)

    Grover, S.B.; Metcalfe, M.P.

    2002-01-01

    A major feature of the Magnox gas cooled reactor design is the graphite core, which acts as the moderator but also provides the physical structure for fuel, control rods, instrumentation and coolant gas channels. The lifetime of a graphite core is dependent upon two principal aging processes: irradiation damage and radiolytic oxidation. Irradiation damage from fast neutrons creates lattice defects leading to changes in physical and mechanical properties and the accumulation of stresses. Radiolytic oxidation is caused by the reaction of oxidizing species from the carbon dioxide coolant gas with the graphite, these species being produced by gamma radiation. Radiolytic oxidation reduces the density and hence the moderating capability of the graphite, but also reduces strength affecting the integrity of core components. In order to manage continued operation over the planned lifetimes of their power stations, BNFL needed to extend their database of the effects of these two phenomena on the ir graphite cores through an irradiation experiment. This paper will discuss the background, purpose, and the processes taken and planned (i.e. post irradiation examination) to ensure meaningful data on the graphite core material is obtained from the irradiation experiment

  17. Special graphites

    International Nuclear Information System (INIS)

    Leveque, P.

    1964-01-01

    A large fraction of the work undertaken jointly by the Commissariat a l'Energie Atomique (CEA) and the Pechiney Company has been the improvement of the properties of nuclear pile graphite and the opening up of new fields of graphite application. New processes for the manufacture of carbons and special graphites have been developed: forged graphite, pyro-carbons, high density graphite agglomeration of graphite powders by cracking of natural gas, impervious graphites. The physical properties of these products and their reaction with various oxidising gases are described. The first irradiation results are also given. (authors) [fr

  18. Testing of different data libraries in activation analysis of concrete and graphite from nuclear installations

    International Nuclear Information System (INIS)

    Cometto, M.; Ancius, D.; Ridikas, D.

    2003-01-01

    With the aging of the nuclear park, decommissioning and dismantling of nuclear installations after their service life is becoming an important issue for the nuclear industry. The radiological characterisation of the equipment and structures present in the reactor and its environment is an essential stage in a decommissioning project since it permits to define and optimize the decommissioning strategy and the disassembling operations. In addition, correct activation estimates are essential for determining the quantity and the nature of the radiological waste generated during decommissioning. The adoption of efficient dismantling procedures and the optimization of the mass flow going to different waste repositories might reduce substantially the total cost of decommissioning. The present work has been done in the framework of the decommissioning and dismantling of the experimental reactor of the University of Strasbourg (RUS). A methodology that combines theoretical calculations and direct measurements has been developed for determining the long-term induced activity in the graphite, concrete and materials present in the reactor. After characterisation of the different elements present in the reactor, it is then possible to plan efficiently the disassembling and dismantling of the system and to optimise the mass flow going to different waste repositories. From a scientific perspective, the comparison of theoretical predictions with experimental values validates the approach and the methodology used in the present study and tests the consistency and the reliability of the nuclear data used for activation analysis. (orig.)

  19. Report on the study of erosion and H-recycle/inventory of carbon/graphite

    International Nuclear Information System (INIS)

    Haasz, A.A.; Davis, J.W.

    1990-04-01

    This study investigated the erosion and hydrogen retention capacity of graphite under plasma exposure by performing controlled plasma simulation experiments using a low-energy high-flux mass analyzed ion accelerator. The authors studied radiation-enhanced sublimation (RES) of graphite, the effect of ion angle of incidence on physical sputtering, the effect of oxygen on hydrocarbon formation during O 2 /H 2 impact, chemical erosion of boron carbide, and the effect of thermal atoms on self-sputtering of graphite. The flux dependence of RES is nearly linear (power of .91) for the extended flux range of 10 13 - 10 17 H + /cm 2 s. Physical sputtering yields were enhanced for off-normal angles of incidence, especially for highly-oriented polished surfaces. Oxygen did not appear to have an effect on the hydrocarbon formation rate; however, some erosion through CO formation was observed. Although large transients were observed in hydrocarbon production in B 4 C, steady-state levels were typically about two orders of magnitude below the erosion rate of graphite. To investigate carbon self-sputtering, thermal H 0 atoms were added to impacting C + ions, simulating a condition existing in the tokamak plasma edge. This led to a synergistic enhancement of the chemical erosion process. For C + /H+0 flux ratios of less than about 10 -1 the chemical erosion yield exceeds unity. Work on hydrogen retention concentrated on the study of H + trapping in different types of graphites as a function of flux and fluence of incident H + . The amount of H trapped in the near-surface region of graphite reaches a saturation level, a function of graphite temperature and impacting H + energy. The amount of H trapped in graphite beyond the ion range was found to increase with increasing fluence and varied for different graphites tested. It seems that hydrogen diffuses through grain boundaries and open porosity in the material until trapped by available carbon bonds

  20. Development and prototype testing of MgCl 2 /graphite foam latent heat thermal energy storage system

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dileep; Yu, Wenhua; Zhao, Weihuan; Kim, Taeil; France, David M.; Smith, Roger K.

    2018-01-01

    Composites of graphite foam infiltrated with a magnesium chloride phase-change material have been developed as high-temperature thermal energy storage media for concentrated solar power applications. This storage medium provides a high thermal energy storage density, a narrow operating temperature range, and excellent heat transfer characteristics. In this study, experimental investigations were conducted on laboratory-scale prototypes with magnesium chloride/graphite foam composite as the latent heat thermal energy storage system. Prototypes were designed and built to monitor the melt front movement during the charging/discharging tests. A test loop was built to ensure the charging/discharging of the prototypes at temperatures > 700 degrees C. Repeated thermal cycling experiments were carried out on the fabricated prototypes, and the experimental temperature profiles were compared to the predicted results from numerical simulations using COMSOL Multiphysics software. Experimental results were found to be in good agreement with the simulations to validate the thermal models.

  1. Sublimation thermodynamics of four fluoroquinolone antimicrobial compounds

    International Nuclear Information System (INIS)

    Blokhina, Svetlana; Sharapova, Angelica; Ol’khovich, Marina; Perlovich, German

    2017-01-01

    Highlights: • The vapor pressures of ciprofloxacin, enrofloxacin, norfloxacin and levofloxacin were measured. • The values of enthalpies, entropies and Gibbs energies of sublimation were calculated at T = 298.15 K. • Thermophysical characteristics of the studied compounds were determined. • The influence hydrogen bonds in crystal lattices on the sublimation enthalpy was discussed. - Abstract: The transpiration method was used to measure the vapor pressures as a function of temperature of the following antimicrobial drugs: ciprofloxacin, enrofloxacin, norfloxacin and levofloxacin. Based on these results standard molar enthalpies, entropies and Gibbs energies of sublimation at T = 298.15 K were calculated and a correlation between the crystal lattice energy and the saturation vapor pressure in a number of fluoroquinolones was found. The thermophysical characteristics of the compounds studied were determined by DSC. The influence of different structural fragments of molecules substituents and the effects of hydrogen bonds in crystal lattices on the sublimation enthalpy was discussed.

  2. Development and testing of nuclear graphite for the German pebble-bed high temperature reactor

    International Nuclear Information System (INIS)

    Haag, G.; Delle, W.; Nickel, H.; Theymann, W.; Wilhelmi, G.

    1987-01-01

    Several types of high temperature reactors have been developed in the Federal Republic of Germany. They are all based on spherical fuel elements being surrounded by graphite as reflector material. As an example, HTR-500 developed by the Hochtemperatur Reaktorbau GmbH is shown. The core consists of the top reflector, the side reflector with inner and outer parts, the bottom reflector and the core support columns. The most serious problem with respect to fast neutron radiation damage had to be solved for the materials of those parts near the pebble bed. Regarding the temperature profile in the core, the top reflector is at 300 deg C, and as cooling gas flows from the top downward, the temperature of the inner side reflector rises to about 700 deg C at the bottom. Fortunately, the highest fast neutron load accumulated during the life time of a reactor corresponds to the lowest temperature. This makes graphite components easier to survive neutron exposure without being mechanically damaged, although the maximum fast neutron fluence is as high as 4 x 10 22 /cm 2 at about 400 deg C. HTR graphite components are divided into four classes according to loading. The raw materials for nuclear graphite, the development of pitch coke nuclear graphite, the irradiation behavior of ATR-2E and ASR-IRS and others are reported. (Kako, I.)

  3. Tests for removal of Co-60 and Eu-154 from irradiated graphite in the TRIGA Reactor

    International Nuclear Information System (INIS)

    Arsene, Carmen

    2009-01-01

    The irradiated graphite in Romania is mainly generated in the thermal columns of TRIGA and WWER-S research reactors (about 9 tones). It was found that the radionuclide content of the graphite irradiated in the TRIGA research reactor is mainly due to C-14 (103 Bq/g), Eu-152 (600-700 Bq/g) and Co-60 (130-150 Bq/g) and low amounts of Eu-154 and Cs-137, depending on location in the thermal column and on irradiation history. In order to minimize the waste inventory and volume in view of their final disposal, in the present paper we show the results of experiments performed for developing and optimizing methods for the chemical decontamination of the irradiated graphite. These procedures are based on strong alkaline solutions for Eu-152 and strong acid solutions for Co-60. The influence of the process parameters on the decontamination factor is investigated. (authors)

  4. Behavior of LASL-made graphite, ZrC, and ZrC-containing coated particles in irradiation tests HT-28 and HT-29

    International Nuclear Information System (INIS)

    Reiswig, R.D.; Wagner, P.; Hollabaugh, C.M.; White, R.W.; O'Rourke, J.A.; Davidson, K.V.; Schell, D.H.

    1976-01-01

    Three types of materials, extruded graphite, hot-pressed ZrC, and particles with ZrC coatings, were irradiated in ORNL High Fluence Isotope Reactor Irradiation tests HT-28 and HT-29. The ZrC seemed unaffected. The graphite changed in dimensions, x-ray diffraction parameters, and thermal conductivity. The four types of coated particles tested all resisted the irradiation well, except one set of particles with double-graded C-ZrC-C coats. Overall, the results were considered encouraging for use of ZrC and extruded graphite fuel matrices. 16 fig

  5. Performance of brazed graphite, carbon-fiber composite, and TZM materials for actively cooled structures: qualification tests

    International Nuclear Information System (INIS)

    Smid, I.; Croessmann, C. D.; Watson, R. D.; Linke, J.; Cardella, A.; Bolt, H.; Reheis, N.; Kny, E.

    1995-01-01

    The divertor of a near-term fusion device has to withstand high heat fluxes, heat shocks, and erosion caused by the plasma. Furthermore, it has to be maintainable through remote techniques. Above all, a good heat removal capability across the interface (low-Z armor/heat sink) plus overall integrity after many operational cycles are needed. To meet all these requirements, an active metal brazing technique is applied to bond graphite and carbon-fiber composite materials to a heat sink consisting of a Mo-41Re coolant tube through a TZM body. Plain brazed graphite and TZM tiles are tested for their fusion-relevant properties. The interfaces appear undamaged after thermal cycling when the melting point of the braze joint is not exceeded and when the graphite armor is > 4 mm thick. High heat flux tests are performed on three actively cooled divertor targets. The braze joints show no sign of failure after exposure to thermal loads ∼ 25 % higher than the design value surface heat flux of 10 MW/m 2 . (author)

  6. Oxidation Resistant Graphite Studies

    Energy Technology Data Exchange (ETDEWEB)

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

  7. Neutron integral test of graphite cross sections in MeV energy region for the JENDL-3T through an analysis of WINFRITH shielding experiment

    International Nuclear Information System (INIS)

    Ueki, Kohtaro; Sakurai, Kiyoshi.

    1988-01-01

    The neutron integral tests of graphite cross sections in MeV neutron energy region for the ENDF/B-IV, JENDL-2, JENDL-3PR1 and -3T were performed through the Monte Carlo analysis of the graphite shielding experiment at the WINFRITH. The measured values were on the reaction rates of 115 In(n,n') 115m In, 27 Al(n,α) 24 Na, 32 S(n,p) 32 P, and 103 Rh(n,n') 103m Rh threshold detectors located in the graphite slabs, so that the experiment on the graphite was good at the integral test of neutron cross sections in MeV energy resion. (author)

  8. Schopenhauer e os paradoxos do sublime

    Directory of Open Access Journals (Sweden)

    François Arnaud

    2012-08-01

    Full Text Available http://dx.doi.org/10.5007/1677-2954.2012v11nesp1p153 A principal distinção entre a concepção schopenhaueriana e kantiana do sublime reside, segundo este artigo, no fato que o observador, no último caso, deve ser submetido a um perigo apenas possível, enquanto no primeiro caso ele deve ser realmente amedrontado. O principal impulso do sentimento do sublime é de fato, em Schopenhauer, a intervenção da vontade, que deve ser portanto realmente ameaçada. Daí resultam alguns paradoxos e originalidades da teoria do sublime de Schopenhauer, principalmente de um ponto de vista ético, cujos vestígios eu tento seguir.

  9. The enthalpy of sublimation of cubane

    International Nuclear Information System (INIS)

    Bashir-Hashemi, A.; Chickos, James S.; Hanshaw, William; Zhao Hui; Farivar, Behzad S.; Liebman, Joel F.

    2004-01-01

    The sublimation enthalpy of cubane, a key reference material for force field and quantum mechanical computations, was measured by combining the vaporization enthalpy at T = 298.15 K to the sum of the fusion enthalpy measured at T = 405 K and a solid-solid phase transition that occurs at T 394 K. The fusion and solid-solid phase transitions were measured previously. A sublimation enthalpy value of (55.2 ± 2.0) kJ mol -1 at T = 298.15 K was obtained. This value compares quite favorably the value obtained by comparing the sublimation enthalpy of similar substances as a function of their molar masses but is at odds with earlier measurements

  10. The enthalpy of sublimation of cubane

    Energy Technology Data Exchange (ETDEWEB)

    Bashir-Hashemi, A.; Chickos, James S.; Hanshaw, William; Zhao Hui; Farivar, Behzad S.; Liebman, Joel F

    2004-12-15

    The sublimation enthalpy of cubane, a key reference material for force field and quantum mechanical computations, was measured by combining the vaporization enthalpy at T = 298.15 K to the sum of the fusion enthalpy measured at T = 405 K and a solid-solid phase transition that occurs at T 394 K. The fusion and solid-solid phase transitions were measured previously. A sublimation enthalpy value of (55.2 {+-} 2.0) kJ mol{sup -1} at T = 298.15 K was obtained. This value compares quite favorably the value obtained by comparing the sublimation enthalpy of similar substances as a function of their molar masses but is at odds with earlier measurements.

  11. Electrochemical treatment of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Podlovilin, V.I.; Egorov, I.M.; Zhernovoj, A.I.

    1983-01-01

    In the course of investigating various modes of electrochemical treatment (ECT) it has been found that graphite anode treatment begins under the ''glow mode''. A behaviour of some marks of graphite with the purpose of ECT technique development in different electrolytes has been tested. Electrolytes have been chosen of three types: highly alkaline (pH 13-14), neutral (pH-Z) and highly acidic (pH 1-2). For the first time parallel to mechanical electroerosion treatment, ECT of graphite and carbon graphite materials previously considered chemically neutral is proposed. ECT of carbon graphite materials has a number of advantages as compared with electroerrosion and mechanical ones with respect to the treatment rate and purity (ronghness) of the surface. A small quantity of sludge (6-8%) under ECT is in highly alkali electrolytes.

  12. Electrochemical treatment of graphite

    International Nuclear Information System (INIS)

    Podlovilin, V.I.; Egorov, I.M.; Zhernovoj, A.I.

    1983-01-01

    In the course of investigating various modes of electroche-- mical treatment (ECT) it has been found that graphite anode treatment begins under the ''glow mode''. A behaviour of some marks of graphite with the purpose of ECT technique development in different electrolytes has been tested. Electrolytes have been chosen of three types: highly alkaline (pH 13-14), neutral (pH-Z) and highly acidic (pH 1-2). For the first time parallel to mechanical electroerosion treatment ECT graphite and carbon graphite materials previously considered chemically neutral is proposed. ECT of carbon graphite materials has a number of advantages as compared with electroerrosion and mechanical ones this is treatment rate and purity (ronghness) of the surface. A sMall quantity of sludge (6-8%) under ECT is in highly alkali electrolytes

  13. Molecular-dynamics study of the dynamical excitations in commensurate monolayer films of nitrogen molecules on graphite: A test of the corrugation in the nitrogen-graphite potential

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, Ludwig Walter

    1995-01-01

    The dynamical excitations in a commensurate monolayer solid of N2 molecules adsorbed on graphite have been studied using molecular-dynamics simulations. Velocity and rotational correlation functions as well as coherent intermediate scattering functions and dynamical structure factors have been ca...

  14. Recommended sublimation pressure and enthalpy of benzene

    Czech Academy of Sciences Publication Activity Database

    Růžička, K.; Fulem, Michal; Červinka, C.

    2014-01-01

    Roč. 68, Jan (2014), s. 40-47 ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : benzene * vapor pressure * heat capacity * ideal - gas thermodynamic properties * sublimation enthalpy * recommended vapor pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.679, year: 2014

  15. Sublimation From Snow in Northern Environments

    Science.gov (United States)

    Pomeroy, J. W.

    2002-12-01

    Sublimation from snow is an often neglected component of water and energy balances. Research under the Mackenzie GEWEX Study has attempted to understand the snow and atmospheric processes controlling sublimation and to estimate the magnitude of sublimation in high latitude catchments. Eddy correlation units were used to measure vertical water vapour fluxes from a high latitude boreal forest, snow-covered tundra and shrub-covered tundra in Wolf Creek Research Basin, near Whitehorse Yukon, Territory Canada. Over Jan-Apr. water vapour fluxes from the forest canopy amounted to 18.3 mm, a significant loss from winter snowfall of 54 mm. Most of this loss occurred when the canopy was snow-covered. The weight of snow measured on a suspended, weighed tree indicates that this flux is dominated by sublimation of intercepted snow. In the melt period (April), water vapour fluxes were uniformly small ranging from 0.21 mm/day on the tundra slope, 0.23 mm/day for the forest and 0.27 mm/day for the shrub-tundra. During the melt period the forest and shrub canopies was snow-free and roots were frozen, so the primary source of water vapour from all sites was the surface snow.

  16. Alan Paton's Sublime: Race, Landscape and the Transcendence of ...

    African Journals Online (AJOL)

    This article develops a postcolonial reading of the sublime by suggesting that aesthetic theories of the sublime were, in their classical philosophical formulations by Edmund Burke and Immanuel Kant, founded on problematic assumptions of racial difference. In the colonial sphere, it is argued, the sublime could discursively ...

  17. Characterization of Ignalina NPP RBMK Reactors Graphite

    International Nuclear Information System (INIS)

    Hacker, P.J.; Neighbour, G.B.; Levinskas, R.; Milcius, D.

    2001-01-01

    The paper concentrates on the investigations of the initial physical properties of graphite used in production of graphite bricks of Ignalina NPP. These graphite bricks are used as nuclear moderator and major core structural components. Graphite bulk density is calculated by mensuration, pore volumes are measured by investigation of helium gas penetration in graphite pore network, the Young's modulus is determined using an ultrasonic time of flight method, the coefficient of thermal expansion is determined using a Netzsch dilatometer 402C, the fractured and machined graphite surfaces are studied using SEM, impurities are investigated qualitatively by EDAX, the degree of graphitization of the material is tested using X-ray diffraction. (author)

  18. Graphite in Science and Nuclear Technology

    OpenAIRE

    Zhmurikov, Evgenij

    2015-01-01

    This review is devoted to the application of graphite and graphite composites in the science and technology. Structure and electrical properties, technological aspects of producing of high-strength artificial graphite and dynamics of its destruction are considered. These type of graphite are traditionally used in the nuclear industry, so author concentrates on actual problems of application and testing of graphite materials in modern science and technology. Translated from chapters 1 of monog...

  19. Mesostructure of graphite composite and its lifetime

    OpenAIRE

    Zhmurikov, Evgenij

    2015-01-01

    This review is devoted to the application of graphite and graphite composites in science and technology. Structure and electrical properties, as so technological aspects of producing of high strength artificial graphite and dynamics of its destruction are considered. These type of graphite are traditionally used in the nuclear industry. Generally, the review relies, on the original results and concentrates on actual problems of application and testing of graphite materials in modern nuclear p...

  20. Estimation of Wear Behavior of Polyphenylene Sulphide Composites Reinforced with Glass/Carbon Fibers, Graphite and Polytetrafluoroethylene, by Pin-on-disc Test

    Directory of Open Access Journals (Sweden)

    M.A.C. Besnea

    2015-03-01

    Full Text Available Wear behavior of polyphenylene sulphide composites was investigated according to load and test speed. Two types of materials were studied: first, with 40 wt% glass fiber, and second, with 10 wt% carbon fiber, 10 wt% graphite and 10 wt%. Tribological tests were performed on the universal tribometer UMT-2, using a pin-on-disc device. The friction coefficient and wear rate for the composites were analyzed. As a result of experimental tests, it was established that polymer composite with polyphenylene sulphide matrix, carbon fibers, graphite and polytetrafluorethylene exhibit good wear behavior under operating conditions.

  1. Fabrication and Testing of Carbon Fiber, Graphite-Epoxy Panels for Submillimeter Telescope Use

    Science.gov (United States)

    Rieger, H.; Helwig, G.; Parks, R. E.; Ulich, B. L.

    1983-12-01

    An experimental carbon-fiber, graphite-epoxy, aluminum Flexcore sandwich panel roughly 1-m square was made by Dornier System, Friedrichshafen, West Germany. The panel was a pre-prototype of the panels to be used in the dish of the 10-m diameter Sub-Millimeter Telescope, a joint project of the Max-Planck-Institute fur Radioastronomie, Bonn, West Germany, and Steward Observatory, the University of Arizona in Tucson. This paper outlines the fabrication process for the panel and indicates the surface accuracy of the panel replication process. To predict the behavior of the panel under various environmental loads, the panel was modeled structurally using anisotropic elements for the core material. Results of this analysis along with experimental verification of these predictions are also given.

  2. The sublimation kinetics of GeSe single crystals

    Science.gov (United States)

    Irene, E. A.; Wiedemeier, H.

    1975-01-01

    The sublimation kinetics of (001) oriented GeSe single crystal platelets was studied by high-temperature mass spectroscopy, quantitative vacuum microbalance techniques, and hot stage optical microscopy. For a mean experimental temperature of 563 K, the activation enthalpy and entropy are found to equal 32.3 kcal/mole and 19.1 eu, respectively. The vaporization coefficient is less than unity for the range of test temperatures, and decreases with increasing temperature. The combined experimental data are correlated by means of a multistep surface adsorption mechanism.

  3. Freezer-sublimer for gaseous diffusion plant

    International Nuclear Information System (INIS)

    Reti, G.R.

    1978-01-01

    A method and apparatus is disclosed for freezing and subliming uranium hexafluoride (UF 6 ) as part of a gaseous diffusion plant from which a quantity of the UF 6 inventory is intermittently withdrawn and frozen to solidify it. A plurality of upright heat pipes holds a coolant and is arranged in a two compartment vessel, the lower compartment is exposed to UF 6 , the higher one serves for condensing the evaporated coolant by means of cooling water. In one embodiment, each pipe has a quantity of coolant such as freon, hermetically sealded therein. In the other embodiment, each pipe is sealed only at the lower end while the upper end communicates with a common vapor or cooling chamber which contains a water cooled condenser. The cooling water has a sufficiently low temperature to condense the evaporated coolant. The liquid coolant flows gravitationally downward to the lower end portion of the pipe. UF 6 gas is flowed into the tank where it contacts the finned outside surface of the heat pipes. Heat from the gas evaporates the coolant and the gas in turn is solidified on the exterior of the heat pipe sections in the tank. To recover UF 6 gas from the tank, the solidified UF 6 is sublimed by passing compressed UF 6 gas over the frozen UF 6 gas on the pipes or by externally heating the lower ends of the pipes sufficiently to evaporate the coolant therein above the subliming temperature of the UF 6 . The subliming UF 6 gas then condenses the coolant in the vertical heat pipes, so that it can gravitationally flow back to the lower end portions

  4. Art, Terrorism and the Negative Sublime

    Directory of Open Access Journals (Sweden)

    Arnold Berleant

    2009-01-01

    Full Text Available The range of the aesthetic has expanded to cover not only a wider range of objects and situations of daily life but also to encompass the negative. This includes terrorism, whose aesthetic impact is central to its use as a political tactic. The complex of positive and negative aesthetic values in terrorism are explored, introducing the concept of the sublime as a negative category to illuminate the analysis and the distinctive aesthetic of terrorism.

  5. Rare earths refining by vacuum sublimation method

    International Nuclear Information System (INIS)

    Rytus, N.N.

    1983-01-01

    The process of rare earths refining by the sUblimation; method in high and superhigh oil-free vacuum, is investigated. The method is effective for rare earths obtaining and permits to prepare metal samples with a high value of electric resistance ratio γ=RsUb(298 K)/Rsub(4.2 K). The estimation of general purity is performed for Sm, Eu, Yb, Tm, Dy, Ho, Er and Se

  6. Artificial graphites

    International Nuclear Information System (INIS)

    Maire, J.

    1984-01-01

    Artificial graphites are obtained by agglomeration of carbon powders with an organic binder, then by carbonisation at 1000 0 C and graphitization at 2800 0 C. After description of the processes and products, we show how the properties of the various materials lead to the various uses. Using graphite enables us to solve some problems, but it is not sufficient to satisfy all the need of the application. New carbonaceous material open application range. Finally, if some products are becoming obsolete, other ones are being developed in new applications [fr

  7. Experiments On Sublimating Carbon Dioxide Ice And Implications For Contemporary Surface Processes On Mars.

    Science.gov (United States)

    Mc Keown, L E; Bourke, M C; McElwaine, J N

    2017-10-27

    Carbon dioxide is Mars' primary atmospheric constituent and is an active driver of Martian surface evolution. CO 2 ice sublimation mechanisms have been proposed for a host of features that form in the contemporary Martian climate. However, there has been very little experimental work or quantitative modelling to test the validity of these hypotheses. Here we present the results of the first laboratory experiments undertaken to investigate if the interaction between sublimating CO 2 ice blocks and a warm, porous, mobile regolith can generate features similar in morphology to those forming on Martian dunes today. We find that CO 2 sublimation can mobilise grains to form (i) pits and (ii) furrows. We have documented new detached pits at the termini of linear gullies on Martian dunes. Based on their geomorphic similarity to the features observed in our laboratory experiments, and on scaling arguments, we propose a new hypothesis that detached pits are formed by the impact of granular jets generated by sublimating CO 2 . We also study the erosion patterns formed underneath a sublimating block of CO 2 ice and demonstrate that these resemble furrow patterns on Mars, suggesting similar formation mechanisms.

  8. Standard test method for graphite furnace atomic absorption spectrometric determination of lead and cadmium extracted from ceramic foodware

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2000-01-01

    1.1 This test method covers procedures for using graphite furnace atomic absorption spectroscopy (GFAAS) to quantitatively determine lead and cadmium extracted by acetic acid at room temperature from the food-contact surface of foodware. The method is applicable to food-contact surfaces composed of silicate-based materials (earthenware, glazed ceramicware, decorated ceramicware, decorated glass, and lead crystal glass) and is capable of determining lead concentrations greater than 0.005 to 0.020 g/mL and cadmium concentrations greater than 0.0005 to 0.002 g/mL, depending on instrument design. 1.2 This test method also describes quality control procedures to check for contamination and matrix interference during GFAAS analyses and a specific sequence of analytical measurements that demonstrates proper instrument operation during the time period in which sample solutions are analyzed. 1.3 Cleaning and other contamination control procedures are described in this test method. Users may modify contamination cont...

  9. Kinetics of dihydro-dibenz[b,f]azepine derivatives sublimation

    International Nuclear Information System (INIS)

    Krongauz, V.V.; Ling, M.T.K.; Woo, L.; Purohit, U.

    2007-01-01

    Sublimation of dihydro-dibenz[b,f]azepine derivatives upon heating was studied and confirmed by thermogravimetry (TGA) and differential scanning calorimetry (DSC). DSC was used to analyze thermodynamics of melting. The kinetics of dihydro-dibenz[b,f]azepine derivatives sublimation were monitored by TGA as a function of temperature. Activation energies of sublimation were deduced and correlated with melting enthalpies and molecular structure. The results indicated that the sublimation was controlled by intermolecular forces in the crystalline lattice of dihydro-dibenz[b,f]azepine derivatives

  10. A graphite foam reinforced by graphite particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.J.; Wang, X.Y.; Guo, L.F.; Wang, Y.M.; Wang, Y.P.; Yu, M.F.; Lau, K.T.T. [DongHua University, Shanghai (China). College of Material Science and Engineering

    2007-11-15

    Graphite foam was obtained after carbonization and graphitization of a pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite particles in a high pressure and temperature chamber. The graphite foam possessed high mechanical strength and exceptional thermal conductivity after adding the graphite particles. Experimental results showed that the thermal conductivity of modified graphite foam reached 110W/m K, and its compressive strength increased from 3.7 MPa to 12.5 MPa with the addition of 5 wt% graphite particles. Through the microscopic observation, it was also found that fewer micro-cracks were formed in the cell wall of the modified foam as compared with pure graphite foam. The graphitization degree of modified foam reached 84.9% and the ligament of graphite foam exhibited high alignment after carbonization at 1200{sup o}C for 3 h and graphitization at 3000{sup o}C for 10 min.

  11. Irradiation Creep in Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Ubic, Rick; Butt, Darryl; Windes, William

    2014-03-13

    An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarly characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.

  12. Reassessing Aesthetic Appreciation of Nature in the Kantian Sublime

    Science.gov (United States)

    Brady, Emily

    2012-01-01

    The sublime has been a relatively neglected topic in recent work in philosophical aesthetics, with existing discussions confined mainly to problems in Kant's theory. Given the revival of interest in his aesthetic theory and the influence of the Kantian sublime compared to other eighteenth-century accounts, this focus is not surprising. Kant's…

  13. Por uma metafísica do sublime

    Directory of Open Access Journals (Sweden)

    Martha de Almeida

    2009-12-01

    Full Text Available The sublime has been analyzed since ancient times with a striking compared with tragedy, whether as a literary genre, whether through Poetics, Aristotle's catharsis we translate the feeling the sublime. In modernity, new names were coming to work with this theory: Hume himself, in his essay The Tragedy, was impressed by the ability of this art form has to produce such strong effects on the viewer. But who else has strengthened analysis of the sublime in modernity, providing the basis for their own Kant was Edmund Burke, with his piece A philosophical investigation on the ideas of the sublime and the beautiful. The third criticism of Kant devoted a special moment to the analysis of the sublime, which had served as basis also for Schopenhauer, however, from her built his own aesthetic that would be of paramount importance Nieztsche for the young, mainly due to the consideration of music as sublime art. Nietzsche, then built his tragic wisdom, with based on the experience of the sublime tragedy.The question this paper wants to treat it exactly: It is possible think of a metaphysics of the sublime, based on Nietzsche?

  14. Purification and preparation of graphite oxide from natural graphite

    Energy Technology Data Exchange (ETDEWEB)

    Panatarani, C., E-mail: c.panatarani@phys.unpad.ac.id; Muthahhari, N.; Joni, I. Made [Instrumentation Systems and Functional Material Processing Laboratory, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Padjadjaran University, Jl. Raya Bandung-Sumedang KM 21, Jatinangor, 45363, Jawa Barat (Indonesia); Rianto, Anton [Grafindo Nusantara Ltd., Belagio Mall Lantai 2, Unit 0 L3-19, Kawasan Mega Kuningan, Kav. B4 No.3, Jakarta Selatan (Indonesia)

    2016-03-11

    Graphite oxide has attracted much interest as a possible route for preparation of natural graphite in the large-scale production and manipulation of graphene as a material with extraordinary electronic properties. Graphite oxide was prepared by modified Hummers method from purified natural graphite sample from West Kalimantan. We demonstrated that natural graphite is well-purified by acid leaching method. The purified graphite was proceed for intercalating process by modifying Hummers method. The modification is on the reaction time and temperature of the intercalation process. The materials used in the intercalating process are H{sub 2}SO{sub 4} and KMNO{sub 4}. The purified natural graphite is analyzed by carbon content based on Loss on Ignition test. The thermo gravimetricanalysis and the Fouriertransform infrared spectroscopy are performed to investigate the oxidation results of the obtained GO which is indicated by the existence of functional groups. In addition, the X-ray diffraction and energy dispersive X-ray spectroscopy are also applied to characterize respectively for the crystal structure and elemental analysis. The results confirmed that natural graphite samples with 68% carbon content was purified into 97.68 % carbon content. While the intercalation process formed a formation of functional groups in the obtained GO. The results show that the temperature and reaction times have improved the efficiency of the oxidation process. It is concluded that these method could be considered as an important route for large-scale production of graphene.

  15. The Sublime, Ugliness and Contemporary Art: A Kantian Perspective

    Directory of Open Access Journals (Sweden)

    Mojca Kuplen

    2015-06-01

    Full Text Available The aim of this paper is twofold. First, to explain the distinction between Kant’s notions of the sublime and ugliness, and to answer an important question that has been left unnoticed in contemporary studies, namely why it is the case that even though both sublime and ugliness are contrapurposive for the power of judgment, occasioning the feeling of displeasure, yet that after all we should feel pleasure in the former, while not in the latter. Second, to apply my interpretation of the sublime and ugliness to contemporary art, and to resolve certain issues that have been raised in accounting for the possibility of artistic sublimity. I argue that an experience of a genuine artistic sublimity is an uncommon occurrence. I propose that the value of contemporary art can be best explained by referring to Kant’s notion of ugliness and his theory of aesthetic ideas.

  16. Management of UKAEA graphite liabilities

    International Nuclear Information System (INIS)

    Wise, M.

    2001-01-01

    The UK Atomic Energy Authority (UKAEA) is responsible for managing its liabilities for redundant research reactors and other active facilities concerned with the development of the UK nuclear technology programme since 1947. These liabilities include irradiated graphite from a variety of different sources including low irradiation temperature reactor graphite (the Windscale Piles 1 and 2, British Energy Pile O and Graphite Low Energy Experimental Pile at Harwell and the Material Testing Reactors at Harwell and Dounreay), advanced gas-cooled reactor graphite (from the Windscale Advanced Gas-cooled Reactor) and graphite from fast reactor systems (neutron shield graphite from the Dounreay Prototype Fast Reactor and Dounreay Fast Reactor). The decommissioning and dismantling of these facilities will give rise to over 6,000 tonnes of graphite requiring disposal. The first graphite will be retrieved from the dismantling of Windscale Pile 1 and the Windscale Advanced Gas-cooled Reactor during the next five years. UKAEA has undertaken extensive studies to consider the best practicable options for disposing of these graphite liabilities in a manner that is safe whilst minimising the associated costs and technical risks. These options include (but are not limited to), disposal as Low Level Waste, incineration, or encapsulation and disposal as Intermediate Level Waste. There are a number of technical issues associated with each of these proposed disposal options; these include Wigner energy, radionuclide inventory determination, encapsulation of graphite dust, galvanic coupling interactions enhancing the corrosion of mild steel and public acceptability. UKAEA is currently developing packaging concepts and designing packaging plants for processing these graphite wastes in consultation with other holders of graphite wastes throughout Europe. 'Letters of Comfort' have been sought from both the Low Level Waste and the Intermediate Level Waste disposal organisations to support the

  17. Graphite nodules in fatigue-tested cast iron characterized in 2D and 3D

    DEFF Research Database (Denmark)

    Mukherjee, Krishnendu; Fæster, Søren; Hansen, Niels

    2017-01-01

    Thick-walled ductile iron casts have been studied by applying (i) cooling rate calculations by FVM, (ii) microstructural characterization by 2D SEM and 3D X-ray tomography techniques and (iii) fatigue testing of samples drawn from components cast in sand molds and metal molds. An analysis has shown...... correlations between cooling rate, structure and fatigue strengths demonstrating the benefit of 3D structural characterization to identify possible causes of premature fatigue failure of ductile cast iron....

  18. Sublime frequencies:  The construction of sublime listening experiences in the sonification of scientific data.

    Science.gov (United States)

    Supper, Alexandra

    2014-02-01

    In the past two decades, the sonification of scientific data - an auditory equivalent of data visualization in which data are turned into sounds - has become increasingly widespread, particularly as an artistic practice and as a means of popularizing science. Sonification is thus part of the recent trend, discussed in public understanding of science literature, towards increased emphasis on 'interactivity' and 'crossovers' between science and art as a response to the perceived crisis in the relationship between the sciences and their publics. However, sonification can also be understood as the latest iteration in a long tradition of theorizing the relations between nature, science and human experience. This article analyses the recent public fascination with sonification and argues that sonification grips public imaginations through the promise of sublime experiences. I show how the 'auditory sublime' is constructed through varying combinations of technological, musical and rhetorical strategies. Rather than maintain a singular conception of the auditory sublime, practitioners draw on many scientific and artistic repertoires. However, sound is often situated as an immersive and emotional medium in contrast to the supposedly more detached sense of vision. The public sonification discourse leaves intact this dichotomy, reinforcing the idea that sound has no place in specialist science.

  19. Graphite surveillance in N Reactor

    International Nuclear Information System (INIS)

    Woodruff, E.M.

    1991-09-01

    Graphite dimensional changes in N Reactor during its 24 yr operating history are reviewed. Test irradiation results, block measurements, stack profiles, top of reflector motion monitors, and visual observations of distortion are described. 18 refs., 14 figs., 1 tab

  20. Thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

    2011-01-01

    A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

  1. The Religious-Sublime in Music, Literature and Architecture

    DEFF Research Database (Denmark)

    Cifuentes-Aldunate, Claudio

    2018-01-01

    The present article is an attempt to propose the semiotic aspect that produces the ”religious- sublime”. Most of the semiotic characteristics that we use to represent (and produce) the signifiers of the religious-sublime, nevertheless, share their mechanisms with other modalities of ”sublimeness......”. The sublime will be regarded as the representation (in the sense of staging) of a perception. I will propose how the subjective perception – in this case of the divinity - is (re)constructed by the subject in a piece of Spanish Gothic literature, in sacred music and in architecture – the room which houses...

  2. AGC-3 Graphite Preirradiation Data Analysis Report

    Energy Technology Data Exchange (ETDEWEB)

    William Windes; David Swank; David Rohrbaugh; Joseph Lord

    2013-09-01

    This report describes the specimen loading order and documents all pre-irradiation examination material property measurement data for the graphite specimens contained within the third Advanced Graphite Capsule (AGC-3) irradiation capsule. The AGC-3 capsule is third in six planned irradiation capsules comprising the Advanced Graphite Creep (AGC) test series. The AGC test series is used to irradiate graphite specimens allowing quantitative data necessary for predicting the irradiation behavior and operating performance of new nuclear graphite grades to be generated which will ascertain the in-service behavior of the graphite for pebble bed and prismatic Very High Temperature Reactor (VHTR) designs. The general design of AGC-3 test capsule is similar to the AGC-2 test capsule, material property tests were conducted on graphite specimens prior to loading into the AGC-3 irradiation assembly. However the 6 major nuclear graphite grades in AGC-2 were modified; two previous graphite grades (IG-430 and H-451) were eliminated and one was added (Mersen’s 2114 was added). Specimen testing from three graphite grades (PCEA, 2114, and NBG-17) was conducted at Idaho National Laboratory (INL) and specimen testing for two grades (IG-110 and NBG-18) were conducted at Oak Ridge National Laboratory (ORNL) from May 2011 to July 2013. This report also details the specimen loading methodology for the graphite specimens inside the AGC-3 irradiation capsule. The AGC-3 capsule design requires "matched pair" creep specimens that have similar dose levels above and below the neutron flux profile mid-plane to provide similar specimens with and without an applied load. This document utilized the neutron flux profile calculated for the AGC-3 capsule design, the capsule dimensions, and the size (length) of the selected graphite and silicon carbide samples to create a stacking order that can produce "matched pairs" of graphite samples above and below the AGC-3 capsule elevation mid-point to

  3. Graphite for high-temperature reactors

    International Nuclear Information System (INIS)

    Hammer, W.; Leushacke, D.F.; Nickel, H.; Theymann, W.

    1976-01-01

    The different graphites necessary for HTRs are being developed, produced and tested within the Federal German ''Development Programme Nuclear Graphite''. Up to now, batches of the following graphite grades have been manufactured and fully characterized by the SIGRI Company to demonstrate reproducibility: pitch coke graphite AS2-500 for the hexagonal fuel elements and exchangeable reflector blocks; special pitch coke graphite ASI2-500 for reflector blocks of the pebble-bed reactor and as back-up material for the hexagonal fuel elements; graphite for core support columns. The material data obtained fulfill most of the requirements under present specifications. Production of large-size blocks for the permanent side reflector and the core support blocks is under way. The test programme covers all areas important for characterizing and judging HTR-graphites. In-pile testing comprises evaluation of the material for irradiation-induced changes of dimensions, mechanical and thermal properties - including behaviour under temperature cycling and creep behaviour - as well as irradiating fuel element segments and blocks. Testing out-of-pile includes: evaluation of corrosion rates and influence of corrosion on strength; strength measurements; including failure criteria. The test programme has been carried out extensively on the AS2-graphite, and the results obtained show that this graphite is suitable as HTGR fuel element graphite. (author)

  4. Bridged graphite oxide materials

    Science.gov (United States)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  5. AGC-2 Graphite Preirradiation Data Package

    Energy Technology Data Exchange (ETDEWEB)

    David Swank; Joseph Lord; David Rohrbaugh; William Windes

    2012-10-01

    The NGNP Graphite R&D program is currently establishing the safe operating envelope of graphite core components for a Very High Temperature Reactor (VHTR) design. The program is generating quantitative data necessary for predicting the behavior and operating performance of the new nuclear graphite grades. To determine the in-service behavior of the graphite for pebble bed and prismatic designs, the Advanced Graphite Creep (AGC) experiment is underway. This experiment is examining the properties and behavior of nuclear grade graphite over a large spectrum of temperatures, neutron fluences and compressive loads. Each experiment consists of over 400 graphite specimens that are characterized prior to irradiation and following irradiation. Six experiments are planned with the first, AGC-1, currently being irradiated in the Advanced Test Reactor (ATR) and pre-irradiation characterization of the second, AGC-2, completed. This data package establishes the readiness of 512 specimens for assembly into the AGC-2 capsule.

  6. Nietzsche's View of Sublimation in the Educational Process

    Science.gov (United States)

    Sharp, Ann Margaret

    1975-01-01

    Article outlined Nietzsche's beliefs on the primary aim of education, the conscious production of the free man through the process of sublimation, the active redirecting of one's life energy in the service of creativity. (Editor/RK)

  7. Some attributes of snow occurrence and snowmelt/sublimation rates ...

    African Journals Online (AJOL)

    Some attributes of snow occurrence and snowmelt/sublimation rates in the Lesotho ... and trimmed MODIS SNOMAP image using the ArcGIS Spatial Analyst tool. ... and hydrology, earth surface processes, and rural livelihoods in the Lesotho ...

  8. Scanning electron microscope observations of sublimates from Merapi Volcano, Indonesia

    Science.gov (United States)

    Symonds, R.

    1993-01-01

    Sublimates were sampled from high-temperature (up to 800??C) fumaroles at Merapi volcano in January 1984. Sampling is accomplished by inserting silica tubes into high-temperature vents. Volcanic glass flows through the tubes and sublimates precipitate on the inner walls in response to the temperature gradient. With decreasing temperature (800-500??C) in the tubes, there are five sublimate zones. Texturally, the sublimate phases grade from large, well-formed crystals at their highest-temperature occurrence to more numerous, smaller crystals that are less perfect at lower temperatures. These changes imply that the crystal nucleation and growth rates increase and decrease, respectively, as temperature decreases. Overall, the textural data suggest that the gas is saturated or slightly super-saturated with the phases at their hottest occurrence, but that the gas becomes increasingly super-saturated with the phases at lower temperatures. -from Author

  9. Process for purifying graphite

    International Nuclear Information System (INIS)

    Clausius, R.A.

    1985-01-01

    A process for purifying graphite comprising: comminuting graphite containing mineral matter to liberate at least a portion of the graphite particles from the mineral matter; mixing the comminuted graphite particles containing mineral matter with water and hydrocarbon oil to form a fluid slurry; separating a water phase containing mineral matter and a hydrocarbon oil phase containing grahite particles; and separating the graphite particles from the hydrocarbon oil to obtain graphite particles reduced in mineral matter. Depending upon the purity of the graphite desired, steps of the process can be repeated one or more times to provide a progressively purer graphite

  10. The Kantian theory of the sublime and humanist politics

    OpenAIRE

    Ayas, Tuğba

    2013-01-01

    Ankara : The Department of Art, Design and Architecture, İhsan Doğramacı Bilkent University, 2013. Thesis (Ph. D.) -- Bilkent University, 2013. Includes bibliographical refences. The German philosopher Immanuel Kant’s rendition of cosmopolitanism and the sublime have been quite popular separately in various discussions on politics and aesthetics since the late 90s. In today’s political conjuncture the Kantian sublime is consulted in describing the social disasters that had b...

  11. O Sublime explicado às crianças

    Directory of Open Access Journals (Sweden)

    Virginia Figueiredo

    2011-01-01

    Full Text Available Como o próprio título indica, este ensaio pretende dialogar com a recepção do sublime kantiano pela filosofia francesa contemporânea, sobretudo com Jean-François Lyotard. Dessa forma, ao invés de ressaltar as consequências inevitável ou sistematicamente morais do sublime kantiano, como fez, de um modo geral, o comentário mais tradicional da filosofia crítica de Kant, este ensaio tenta interpretar o sublime como sendo essencialmente uma experiência da arte, seguindo assim de perto aquela tradição francesa. Mas, ao mesmo tempo, tomando alguma distância, este texto quer fazer uma objeção ao fundamento exclusivamente burkiano da concepção de sublime de Lyotard. Em suma, quero defender que é possível privilegiar o tempo (aspecto central do sublime de Edmund Burke, segundo Lyotard também na experiência do sublime kantiano.

  12. Sublimity and beauty: A view from nursing aesthetics.

    Science.gov (United States)

    Siles-González, José; Solano-Ruiz, Carmen

    2016-03-01

    Several authors have focused on the aesthetics of nursing care from diverse perspectives; however, there are few studies about the sublime and the beautiful in nursing. To identify beautiful and sublime moments in the context of the aesthetics of nursing care. A theoretical reflection has been contemplated about sublime and beautiful values in the context of the aesthetics of nursing care from the cultural history perspective. For that purpose, a revision of this issue has been completed. The terms 'beautiful' and 'sublime' have been analysed to identify the characteristics of both in the context of nursing care. We have followed all ethical requirements regarding the sources, conducting research and authorship. There is no conflict of interest in this paper. With aesthetic knowledge, the nurse expresses the artistic nature of nursing care by appreciating the act of caring for individuals. The sublime is a complex phenomenon, since apparently contrary feelings are interwoven. Nursing care is an art with an anthropological object-subject on which the 'artist' applies their prior knowledge and skills. Feelings and emotions that develop during the clinical nursing practice - especially at times sublime and beautiful, aesthetic - constitute experiences which are professionally significant. © The Author(s) 2015.

  13. 77 FR 51581 - Request for a License To Export Nuclear Grade Graphite

    Science.gov (United States)

    2012-08-24

    ... NUCLEAR REGULATORY COMMISSION Request for a License To Export Nuclear Grade Graphite Pursuant to... 27, 2012, graphite for of nuclear grade graphite to the XMAT424, 11006032. nuclear end use. graphite. Shanghai Institute of Applied Physics in China to test various types of nuclear grade graphite material in...

  14. Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

    International Nuclear Information System (INIS)

    Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke

    2015-01-01

    Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysis also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs

  15. Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)

    2015-02-23

    Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysis also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs.

  16. O paradoxo sublime ou a alforria da arte

    Directory of Open Access Journals (Sweden)

    Virgínia Figueiredo

    2015-01-01

    Full Text Available Neste texto, pretendo analisar a tese principal do ensaio “A verdade sublime” de Philippe Lacoue-Labarthe, a qual poderia ser formulada do seguinte modo: a verdade sublime é o Ereignis, esse é o fundamento a partir do qual se desenvolveu uma dificílima operação que consistiu em modificar a tradição do sublime sempre apresentado negativamente naquilo que Lacoue-Labarthe chamou de "compreensão afirmativa do sublime ou da grande arte". O autor estabelece uma astuciosa aliança entre o que há de mais radical no pensamento de Heidegger e o sublime, tratado de maneira bastante polêmica, como a principal teoria da arte de Kant. Dessa articulação fundamental, pode-se concluir que ele não está apenas à procura de uma “Estética” (sequer de uma “Teoria da Arte” sublime, mas, em busca de algo que é muito mais ambicioso, a saber: de um pensamento do sublime. Portanto, na minha opinião, o ensaio lacouelabarthiano constitui, por um lado, uma referência indispensável não só a quem quer que pretenda estudar a tradição do sublime, mas, por outro, compreender o pensamento heideggeriano sobre a arte e sua tentativa de encontrar uma determinação mais essencial e, sobretudo, ousaria dizer, mais política da arte.

  17. Erosion of pyrolytic graphite and Ti-doped graphite due to high flux irradiation

    International Nuclear Information System (INIS)

    Ohtsuka, Yusuke; Ohashi, Junpei; Ueda, Yoshio; Isobe, Michiro; Nishikawa, Masahiro

    1997-01-01

    The erosion of pyrolytic graphite and titanium doped graphite RG-Ti above 1,780 K was investigated by 5 keV Ar beam irradiation with the flux from 4x10 19 to 1x10 21 m -2 ·s -1 . The total erosion yields were significantly reduced with the flux. This reduction would be attributed to the reduction of RES (radiation enhanced sublimation) yield, which was observed in the case of isotropic graphite with the flux dependence of RES yield of φ -0.26 (φ: flux) obtained in our previous work. The yield of pyrolytic graphite was roughly 30% higher than that of isotropic graphite below the flux of 10 20 m -2 ·s -1 whereas each yield approached to very close value at the highest flux of 1x10 21 m -2 ·s -1 . This result indicated that the effect of graphite structure on the RES yield, which was apparent in the low flux region, would disappear in the high flux region probably due to the disordering of crystal structure. In the case of irradiation to RG-Ti at 1,780 K, the surface undulations evolved with a mean height of about 3 μm at 1.2x10 20 m -2 ·s -1 , while at higher flux of 8.0x10 20 m -2 ·s -1 they were unrecognizable. These phenomena can be explained by the reduction of RES of graphite parts excluding TiC grains. (author)

  18. Practical sublimation source for large-scale chromium gettering in fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Simpkins, J E; Gabbard, W A; Emerson, L C; Mioduszewski, P K [Oak Ridge National Lab., TN (USA)

    1984-05-01

    This paper describe the fabrication and testing of a large-scale chromium sublimation source that resembles the VARIAN Ti-ballsup(TM) in its design. The device consists of a hollow chromium sphere with a diameter of approximately 3 cm and an incandescent filament for radiation heating from inside the ball. We also discuss the gettering technique utilizing this source. The experimental arrangement consists of an ultrahigh vacuum (UHV) system instrumented for total and partial pressure measurements, a film thickness monitor, thermocouples, an optical pyrometer, and appropriate instrumentation to measure the heating power. The results show the temperature and corresponding sublimation rate of the Cr-ball as functions of input power. In addition, an example of the total pumping speed of a gettered surface is shown.

  19. A practical sublimation source for large-scale chromium gettering in fusion devices

    International Nuclear Information System (INIS)

    Simpkins, J.E.; Gabbard, W.A.; Emerson, L.C.; Mioduszewski, P.K.

    1984-01-01

    This paper describe the fabrication and testing of a large-scale chromium sublimation source that resembles the VARIAN Ti-ballsup(TM) in its design. The device consists of a hollow chromium sphere with a diameter of approximately 3 cm and an incandescent filament for radiation heating from inside the ball. We also discuss the gettering technique utilizing this source. The experimental arrangement consists of an ultrahigh vacuum (UHV) system instrumented for total and partial pressure measurements, a film thickness monitor, thermocouples, an optical pyrometer, and appropriate instrumentation to measure the heating power. The results show the temperature and corresponding sublimation rate of the Cr-ball as functions of input power. In addition, an example of the total pumping speed of a gettered surface is shown. (orig.)

  20. A study of graphite-epoxy laminate failures due to high transverse shear strains using the multi-span-beam shear test procedure

    Science.gov (United States)

    Jegley, Dawn C.

    1989-01-01

    The multi-span-beam shear test procedure is used to study failure mechanisms in graphite-epoxy laminates due to high transverse shear strains induced by severe local bending deformations in test specimens. Results of a series of tests on specimens with a variety of stacking sequences, including some with adhesive interleaving, are presented. These results indicate that laminates with stacking sequences with several + or - 45 and 90 deg plies next to each other are more susceptible to failures due to high transverse shear strains than laminates with + or - 45 and 0 deg plies next to each other or with + or - 45 deg plies next to layers of adhesive interleaving. Results of these tests are compared with analytical results based on finite elements.

  1. Principle design and data of graphite components

    International Nuclear Information System (INIS)

    Ishihara, Masahiro; Sumita, Junya; Shibata, Taiju; Iyoku, Tatsuo; Oku, Tatsuo

    2004-01-01

    The High Temperature Engineering Test Reactor (HTTR) constructed by Japan Atomic Energy Research Institute (JAERI) is a graphite-moderated and helium-gas-cooled reactor with prismatic fuel elements of hexagonal blocks. The reactor internal structures of the HTTR are mainly made up of graphite components. As well known, the graphite is a brittle material and there were no available design criteria for brittle materials. Therefore, JAERI had to develop the design criteria taking account of the brittle fracture behavior. In this paper, concept and key specification of the developed graphite design criteria is described, and also an outline of the quality control specified in the design criteria is mentioned

  2. Vapor pressures and sublimation enthalpies of novel bicyclic heterocycle derivatives

    International Nuclear Information System (INIS)

    Blokhina, Svetlana V.; Ol’khovich, Marina V.; Sharapova, Angelica V.; Perlovich, German L.; Proshin, Alexey N.

    2014-01-01

    Highlights: • The vapor pressures of novel bicyclo-derivatives of amine were measured. • Thermodynamic functions of sublimation were calculated. • The influence of substituent structure and chemical nature on the vapor pressure was studied. -- Abstract: The vapor pressures of five novel bicyclic heterocycle derivatives were measured over the temperature 341.15 to 396.15 K using the transpiration method by means of an inert gas carrier. From these results the standard enthalpies and Gibbs free energies of sublimation at the temperature 298.15 K were calculated. The effects of alkyl- and chloro-substitutions on changes in the thermodynamic functions have been investigated. Quantitative structure–property relationship on the basis HYBOT physico-chemical descriptors for biologically active compounds have been developed to predict the sublimation enthalpies and Gibbs free energies of the compounds studied

  3. Enthalpy of sublimation as measured using a silicon oscillator

    Science.gov (United States)

    Shakeel, Hamza; Pomeroy, J. M.

    In this study, we report the enthalpy of sublimation of common gases (nitrogen, oxygen, argon, carbon dioxide, neon, krypton, xenon, and water vapor) using a large area silicon oscillator with a sub-ng (~0.027 ng/cm2) mass sensitivity. The double paddle oscillator design enables high frequency stability (17 ppb) at cryogenic temperatures and provides a consistent technique for enthalpy measurements. The enthalpies of sublimation are derived from the rate of mass loss during programmed thermal desorption and are detected as a change in the resonance frequency of the self-tracking oscillator. These measured enthalpy values show excellent agreement with the accepted literature values.

  4. Of images and ills. Uses and malaises of sublimation

    Directory of Open Access Journals (Sweden)

    Georges Didi-Huberman

    2017-05-01

    Full Text Available This text is published as postface to the new edition of Invention de l'hystérie. Charcot et l’iconographie photographique de l’hystérie (Macula, Paris, 2012, pp. 364-405 with the title Des images et des maux. It’s also the full version of the lecture organized by the Association Psychanalytique de France (September 24, 2011, entitled L’Usage de la sublimation. Starting from some considerations on his first book, the Author examines limits and potentials of the notion of sublimation in reference with art and artistic creation, and suggests a different way to approach it.

  5. Snow sublimation in mountain environments and its sensitivity to forest disturbance and climate warming

    Science.gov (United States)

    Sexstone, Graham A.; Clow, David W.; Fassnacht, Steven R.; Liston, Glen E.; Hiemstra, Christopher A.; Knowles, John F.; Penn, Colin A.

    2018-01-01

    Snow sublimation is an important component of the snow mass balance, but the spatial and temporal variability of this process is not well understood in mountain environments. This study combines a process‐based snow model (SnowModel) with eddy covariance (EC) measurements to investigate (1) the spatio‐temporal variability of simulated snow sublimation with respect to station observations, (2) the contribution of snow sublimation to the ablation of the snowpack, and (3) the sensitivity and response of snow sublimation to bark beetle‐induced forest mortality and climate warming across the north‐central Colorado Rocky Mountains. EC‐based observations of snow sublimation compared well with simulated snow sublimation at stations dominated by surface and canopy sublimation, but blowing snow sublimation in alpine areas was not well captured by the EC instrumentation. Water balance calculations provided an important validation of simulated sublimation at the watershed scale. Simulated snow sublimation across the study area was equivalent to 28% of winter precipitation on average, and the highest relative snow sublimation fluxes occurred during the lowest snow years. Snow sublimation from forested areas accounted for the majority of sublimation fluxes, highlighting the importance of canopy and sub‐canopy surface sublimation in this region. Simulations incorporating the effects of tree mortality due to bark‐beetle disturbance resulted in a 4% reduction in snow sublimation from forested areas. Snow sublimation rates corresponding to climate warming simulations remained unchanged or slightly increased, but total sublimation losses decreased by up to 6% because of a reduction in snow covered area and duration.

  6. The sublime and the grotesque: obscenity in Hilda Hilst

    Directory of Open Access Journals (Sweden)

    Jo A-mi

    2016-08-01

    Full Text Available The present work aims to discuss the dialogical relationship between sublime and grotesque in the work A obscena Senhora D by Hilda Hilst, based on its status of contemporary fiction permeated by reconditioning of the language in its performance in the non-linear time. In this sense, it was used studies of the sublime, as a historical and philosophical and literary concept in the works of Longinus, Edmund Burke, Immanuel Kant, Victor Hugo and François Lyotard; issues relating to discussions on the grotesque and its dialogue with the sublime ways, the works of Mikhail Bakhtin and Michel Maffesoli had great importance - the poetic and obscene relationship of the work discussed in convergent concepts such as obscenity, eroticism, sacred and profane. From these analyzes, it was concluded that in A obscena senhora D the sublime and the grotesque show in a multifaceted character, contradictory, interlocutory, and therefore not exclusionary: solidifying the hybrid linguistic-imagistic flow of the hilstiana literature.

  7. Sublimation-Induced Shape Evolution of Silver Cubes

    KAUST Repository

    Ding, Yong

    2009-12-18

    The heat is on: Surface sublimation and shape transformation of silver cubes, enclosed by {100} surfaces and about 100nm in size, are examined by in situ transmission electron microscopy (see picture). High-index surfaces, such as {110}, of face-centered cubic metals are more stable when the temperature is close to the melting point.

  8. Sublimation as a landform-shaping process on Pluto

    Science.gov (United States)

    Moore, Jeffrey M.; Howard, Alan D.; Umurhan, Orkan M.; White, Oliver L.; Schenk, Paul M.; Beyer, Ross A.; McKinnon, William B.; Spencer, John R.; Grundy, Will M.; Lauer, Tod R.; Nimmo, Francis; Young, Leslie A.; Stern, S. Alan; Weaver, Harold A.; Olkin, Cathy B.; Ennico, Kimberly; New Horizons Science Team

    2017-05-01

    Fields of pits, both large and small, in Tombaugh Regio (Sputnik Planitia, and the Pitted Uplands to the east), and along the scarp of Piri Rupes, are examples of landscapes on Pluto where we conclude that sublimation drives their formation and evolution. Our heuristic modeling closely mimics the form, spacing, and arrangement of a variety of Tombaugh Regio's pits. Pluto's sublimation modified landforms appear to require a significant role for (diffusive) mass wasting as suggested by our modeling. In our models, the temporal evolution of pitted surfaces is such that initially lots of time passes with little happening, then eventually, very rapid development of relief and rapid sublimation. Small pits on Sputnik Planitia are consistent with their formation in N2-dominated materials. As N2-ice readily flows, some other ``stiffer'' volatile ice may play a role in supporting the relief of sublimation degraded landforms that exhibit several hundred meters of relief. A strong candidate is CH4, which is spectroscopically observed to be associated with these features, but the current state of rheological knowledge for CH4 ice at Pluto conditions is insufficient for a firm assessment.

  9. The Religious-Sublime in Music, Literature and Architecture

    DEFF Research Database (Denmark)

    Cifuentes-Aldunate, Claudio

    2018-01-01

    The present article is an attempt to propose the semiotic aspect that produces the ”religious- sublime”. Most of the semiotic characteristics that we use to represent (and produce) the signifiers of the religious-sublime, nevertheless, share their mechanisms with other modalities of ”sublimeness”...

  10. Sublimation-Induced Shape Evolution of Silver Cubes

    KAUST Repository

    Ding, Yong; Fan, Fengru; Tian, Zhongqun; Wang, Zhong Lin

    2009-01-01

    The heat is on: Surface sublimation and shape transformation of silver cubes, enclosed by {100} surfaces and about 100nm in size, are examined by in situ transmission electron microscopy (see picture). High-index surfaces, such as {110}, of face

  11. System for NO reduction using sublimation of cyanuric acid

    Science.gov (United States)

    Perry, R.A.

    1989-01-24

    An arrangement for reducing the NO content of a gas stream comprises contacting the gas stream with HNCO at a temperature effective for heat induced decomposition of HNCO and for resultant lowering of the NO content of the gas stream. Preferably, the HNCO is generated by sublimation of cyanuric acid. 1 fig.

  12. Modular Porous Plate Sublimator /MPPS/ requires only water supply for coolant

    Science.gov (United States)

    Rathbun, R. J.

    1966-01-01

    Modular porous plate sublimators, provided for each location where heat must be dissipated, conserve the battery power of a space vehicle by eliminating the coolant pump. The sublimator requires only a water supply for coolant.

  13. Phonon scattering in graphite

    International Nuclear Information System (INIS)

    Wagner, P.

    1976-04-01

    Effects on graphite thermal conductivities due to controlled alterations of the graphite structure by impurity addition, porosity, and neutron irradiation are shown to be consistent with the phonon-scattering formulation 1/l = Σ/sub i equals 1/sup/n/ 1/l/sub i/. Observed temperature effects on these doped and irradiated graphites are also explained by this mechanism

  14. Experience with graphite in JET

    International Nuclear Information System (INIS)

    Pick, M.A.; Celentano, G.; Deksnis, E.; Dietz, K.J.; Shaw, R.; Sonnenberg, K.; Walravens, M.

    1987-01-01

    During the current operational period of JET more than 50% of the internal area of the machine is covered in graphite tiles. This includes the 15 m 2 of carbon tiles installed in the new toroidal limiter, the 40 poloidal belts of graphite tiles covering the U-joints and bellows as well as a two metre high ring (-- 20 m 2 ) or carbon tiles on the inner wall of the Torus. A ring of tiles in the equatorial plane (3 tiles high) consists of carbon-carbon fibre tiles. Test bed results indicated that the fine grained graphite tiles cracked at ∼ 1 kW/cm 2 for 2s of irradiation whereas the carbon-carbon fibre tiles were able to sustain a flux, limited by the irradiation facility, of 3.5 kW for 3s without any damage. The authors report on the generally positive experience they have had had with the installed graphite during the present and previous in-vessel configurations. This includes the physical integrity of the tiles under severe conditions such as high energy run-away electron beams, plasma disruptions and high heat fluxes. They report on the importance of the precise positioning of the inner wall and x-point tiles at the very high power fluxes of JET and the effect of deviations on both graphite and carbon-fibre tiles

  15. Aerosol volatility and enthalpy of sublimation of carboxylic acids.

    Science.gov (United States)

    Salo, Kent; Jonsson, Asa M; Andersson, Patrik U; Hallquist, Mattias

    2010-04-08

    The enthalpy of sublimation has been determined for nine carboxylic acids, two cyclic (pinonic and pinic acid) and seven straight-chain dicarboxylic acids (C(4) to C(10)). The enthalpy of sublimation was determined from volatility measurements of nano aerosol particles using a volatility tandem differential mobility analyzer (VTDMA) set-up. Compared to the previous use of a VTDMA, this novel method gives enthalpy of sublimation determined over an extended temperature range (DeltaT approximately 40 K). The determined enthalpy of sublimation for the straight-chain dicarboxylic acids ranged from 96 to 161 kJ mol(-1), and the calculated vapor pressures at 298 K are in the range of 10(-6)-10(-3) Pa. These values indicate that dicarboxylic acids can take part in gas-to-particle partitioning at ambient conditions and may contribute to atmospheric nucleation, even though homogeneous nucleation is unlikely. To obtain consistent results, some experimental complications in producing nanosized crystalline aerosol particles were addressed. It was demonstrated that pinonic acid "used as received" needed a further purification step before being suspended as a nanoparticle aerosol. Furthermore, it was noted from distinct differences in thermal properties that aerosols generated from pimelic acid solutions gave two types of particles. These two types were attributed to crystalline and amorphous configurations, and based on measured thermal properties, the enthalpy of vaporization was 127 kJ mol(-1) and that of sublimation was 161 kJ mol(-1). This paper describes a new method that is complementary to other similar methods and provides an extension of existing experimental data on physical properties of atmospherically relevant compounds.

  16. Surface and snowdrift sublimation at Princess Elisabeth station, East Antarctica

    Directory of Open Access Journals (Sweden)

    W. Thiery

    2012-08-01

    Full Text Available In the near-coastal regions of Antarctica, a significant fraction of the snow precipitating onto the surface is removed again through sublimation – either directly from the surface or from drifting snow particles. Meteorological observations from an Automatic Weather Station (AWS near the Belgian research station Princess Elisabeth in Dronning Maud Land, East-Antarctica, are used to study surface and snowdrift sublimation and to assess their impacts on both the surface mass balance and the surface energy balance during 2009 and 2010. Comparison to three other AWSs in Dronning Maud Land with 11 to 13 yr of observations shows that sublimation has a significant influence on the surface mass balance at katabatic locations by removing 10–23% of their total precipitation, but at the same time reveals anomalously low surface and snowdrift sublimation rates at Princess Elisabeth (17 mm w.e. yr−1 compared to 42 mm w.e. yr−1 at Svea Cross and 52 mm w.e. yr−1 at Wasa/Aboa. This anomaly is attributed to local topography, which shields the station from strong katabatic influence, and, therefore, on the one hand allows for a strong surface inversion to persist throughout most of the year and on the other hand causes a lower probability of occurrence of intermediately strong winds. This wind speed class turns out to contribute most to the total snowdrift sublimation mass flux, given its ability to lift a high number of particles while still allowing for considerable undersaturation.

  17. AGC-2 Graphite Preirradiation Data Analysis Report

    Energy Technology Data Exchange (ETDEWEB)

    William Windes; W. David Swank; David Rohrbaugh; Joseph Lord

    2013-08-01

    This report described the specimen loading order and documents all pre-irradiation examination material property measurement data for the graphite specimens contained within the second Advanced Graphite Capsule (AGC-2) irradiation capsule. The AGC-2 capsule is the second in six planned irradiation capsules comprising the Advanced Graphite Creep (AGC) test series. The AGC test series is used to irradiate graphite specimens allowing quantitative data necessary for predicting the irradiation behavior and operating performance of new nuclear graphite grades to be generated which will ascertain the in-service behavior of the graphite for pebble bed and prismatic Very High Temperature Reactor (VHTR) designs. Similar to the AGC-1 specimen pre-irradiation examination report, material property tests were conducted on specimens from 18 nuclear graphite types but on an increased number of specimens (512) prior to loading into the AGC-2 irradiation assembly. All AGC-2 specimen testing was conducted at Idaho National Laboratory (INL) from October 2009 to August 2010. This report also details the specimen loading methodology for the graphite specimens inside the AGC-2 irradiation capsule. The AGC-2 capsule design requires “matched pair” creep specimens that have similar dose levels above and below the neutron flux profile mid-plane to provide similar specimens with and without an applied load. This document utilized the neutron flux profile calculated for the AGC-2 capsule design, the capsule dimensions, and the size (length) of the selected graphite and silicon carbide samples to create a stacking order that can produce “matched pairs” of graphite samples above and below the AGC-2 capsule elevation mid-point to provide specimens with similar neutron dose levels.

  18. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Kumar, N.; Radhika, R.; Kozakov, A.T.; Pandian, R.; Chakravarty, S.; Ravindran, T.R.; Dash, S.; Tyagi, A.K.

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  19. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  20. Robust Magnetic Properties of a Sublimable Single-Molecule Magnet.

    Science.gov (United States)

    Kiefl, Evan; Mannini, Matteo; Bernot, Kevin; Yi, Xiaohui; Amato, Alex; Leviant, Tom; Magnani, Agnese; Prokscha, Thomas; Suter, Andreas; Sessoli, Roberta; Salman, Zaher

    2016-06-28

    The organization of single-molecule magnets (SMMs) on surfaces via thermal sublimation is a prerequisite for the development of future devices for spintronics exploiting the richness of properties offered by these magnetic molecules. However, a change in the SMM properties due to the interaction with specific surfaces is usually observed. Here we present a rare example of an SMM system that can be thermally sublimated on gold surfaces while maintaining its intact chemical structure and magnetic properties. Muon spin relaxation and ac susceptibility measurements are used to demonstrate that, unlike other SMMs, the magnetic properties of this system in thin films are very similar to those in the bulk, throughout the full volume of the film, including regions near the metal and vacuum interfaces. These results exhibit the robustness of chemical and magnetic properties of this complex and provide important clues for the development of nanostructures based on SMMs.

  1. Trust: the sublime duty in health care leadership.

    Science.gov (United States)

    Piper, Llewellyn E

    2010-01-01

    Trust is the essence of human social existence. From the moment of birth, trust is the basic component in any human relationship and interaction. Trust is the Holy Grail for human confidence in others. From human survival to organizational survival, trust is the primordial bond. No organization is more dependent on trust than health care. This article views trust as the most basic fundamental quality for leadership. Trust is a sublime duty of a leader and the leadership of an organization. Leadership sets the culture of trust. Trust is the one quality that is essential for guiding an organization toward serving others. This article addresses trust from many perspectives. Trust is viewed from our subordinates, our peers, our superiors, and the public we serve. This article postulates how trust in an organization is the sublime duty of leadership that unites all human understanding and without it destroys all human relationships.

  2. Metal/graphite-composite materials for fusion device

    International Nuclear Information System (INIS)

    Kneringer, G.; Kny, E.; Fischer, W.; Reheis, N.; Staffler, R.; Samm, U.; Winter, J.

    1995-01-01

    The utilization of graphite as a structural material depends to an important extent on the availability of a joining technique suitable for the production of reliable large scale metal/graphite-composites. This study has been conducted to evaluate vacuum brazes and procedures for graphite and metals which can be used in fusion applications up to about 1500 degree C. The braze materials included: AgCuTi, CuTi, NiTi, Ti, ZrTi, Zr. Brazing temperatures ranged from 850 degree C to 1900 degree C. The influence of graphite quality on wettability and pore-penetration of the braze has been investigated. Screening tests of metal/graphite-assemblies with joint areas exceeding some square-centimeters have shown that they can only successfully be produced when graphite is brazed to a metal, such as tungsten or molybdenum with a coefficient of thermal expansion closely matching that of graphite. Therefore all experimental work on evaluation of joints has been concentrated on molybdenum/graphite brazings. The tensile strength of molybdenum/graphite-composites compares favorably with the tensile strength of bulk graphite from room temperature close to the melting temperature of the braze. In electron beam testing the threshold damage line for molybdenum/graphite-composites has been evaluated. Results show that even composites with the low melting AgCuTi-braze are expected to withstand 10 MW/m 2 power density for at least 10 3 cycles. Limiter testing in TEXTOR shows that molybdenum/graphite-segments with 3 mm graphite brazed on molybdenum-substrate withstand severe repeated TEXTOR plasma discharge conditions without serious damage. Results prove that actively cooled components on the basis of a molybdenum/graphite-composite can sustain a higher heat flux than bulk graphite alone. (author)

  3. Theoretical and experimental investigation of the destruction of graphites in a flow of dissociated air

    Science.gov (United States)

    Bovina, T. A.; Zviagin, Y. V.; Markelov, N. V.; Chudetskiy, Y. V.

    1986-01-01

    A method is presented for calculating the heating and erosion of blunt bodies made of graphite in a high-enthalpy flow of dissociated air, assuming chemical equilibrium on the surface and taking account of the thermal effects of combustion and sublimation of graphite. The analysis involves the use of a finite difference scheme to solve an equation of unsteady heat conduction. Attention is given to the equilibrium vaporization of C, C2 and C3 molecules. The calculations agree well with experimental data for a wide range of temperatures and stagnation pressures.

  4. TRIGGERING SUBLIMATION-DRIVEN ACTIVITY OF MAIN BELT COMETS

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, N. [Institute for Astronomy, University of Hawaii-Manoa, Honolulu, HI 96825 (United States); Maindl, T. I.; Dvorak, R. [Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Schäfer, C. [Institut für Astronomie und Astrophysik, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen (Germany); Speith, R., E-mail: nader@ifa.hawaii.edu [Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen (Germany)

    2016-10-10

    It has been suggested that the comet-like activity of main belt comets (MBCs) is due to the sublimation of sub-surface water–ice that has been exposed as a result of their surfaces being impacted by meter-sized bodies. We have examined the viability of this scenario by simulating impacts between meter-sized and kilometer-sized objects using a smooth particle hydrodynamics approach. Simulations have been carried out for different values of the impact velocity and impact angle, as well as different target material and water-mass fractions. Results indicate that for the range of impact velocities corresponding to those in the asteroid belt, the depth of an impact crater is slightly larger than 10 m, suggesting that if the activation of MBCs is due to the sublimation of sub-surface water–ice, this ice has to exist no deeper than a few meters from the surface. Results also show that ice exposure occurs in the bottom and on the interior surface of impact craters, as well as on the surface of the target where some of the ejected icy inclusions are re-accreted. While our results demonstrate that the impact scenario is indeed a viable mechanism to expose ice and trigger the activity of MBCs, they also indicate that the activity of the current MBCs is likely due to ice sublimation from multiple impact sites and/or the water contents of these objects (and other asteroids in the outer asteroid belt) is larger than the 5% that is traditionally considered in models of terrestrial planet formation, providing more ice for sublimation. We present the details of our simulations and discuss their results and implications.

  5. Optimization of fast dissolving etoricoxib tablets prepared by sublimation technique

    OpenAIRE

    Patel D; Patel M

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 3 2 ...

  6. El Silencio de la Sirena: lo Sublime en Alejandra Pizarnik

    Directory of Open Access Journals (Sweden)

    Julieta Lerman

    2012-12-01

    Full Text Available Algunas poéticas de las décadas del cincuenta y del sesenta parecerían constituirse en torno a un vacío, un silencio que a veces inspira la palabra poética y otras veces la aborta. Esa ambigüedad, característica de la poética de Alejandra Pizarnik, podemos entenderla como una “reedición” de la estética de lo sublime. Lo sublime es un concepto estético-filosófico que plantearon filósofos como Inmanuel Kant y Edmund Burke para pensar el arte romántico y, en el siglo XX, otros autores como Jean-François Lyotard, lo retomaron para analizar el arte de vanguardia. Así, lo sublime nos permite repensar la poética de Pizarnik en sus coincidencias y oposiciones a otras de la tradición moderna (como la de Charles Baudelaire o de las vanguardias latinoamericanas (como Oliverio Girondo y Vicente Huidobro.

  7. Ad infinitum: implicaciones de lo sublime en la contemporaneidad

    Directory of Open Access Journals (Sweden)

    Miguel Ángel Gaete Cáceres

    2014-12-01

    Full Text Available El presente texto es un estudio que ofrece una revisión crítica al concepto de lo sublime basándose en la teorización clásica de esta idea, es decir, la adjudicada a Longino, Edmund Burke e Immanuel Kant. A partir de aquí, se intentará descubrir la presencia de lo sublime como un factor relevante en la configuración cultural del mundo contemporáneo, pasando por su presencia innegable en el arte de las vanguardias o en la concepción de la Naturaleza y el entorno. Finalmente, el objetivo central de este escrito es demostrar como lo sublime ofrece también una alternativa para comprender el problema de "lo infinito" y "lo ilimitado" en el marco de las tecnologías, la eclosión de las grandes ciudades y su filtración en el sustrato retórico del capitalismo, ofreciendo así una vía diferente en el estudio de este tema clásico de la estética.

  8. El Silencio de la Sirena: lo Sublime en Alejandra Pizarnik

    Directory of Open Access Journals (Sweden)

    Julieta Lerman

    2012-03-01

    Full Text Available http://dx.doi.org/10.5007/1984-784X.2012v12n17p85 Algunas poéticas de las décadas del cincuenta y del sesenta parecerían constituirse en torno a un vacío, un silencio que a veces inspira la palabra poética y otras veces la aborta. Esa ambigüedad, característica de la poética de Alejandra Pizarnik, podemos entenderla como una “reedición” de la estética de lo sublime. Lo sublime es un concepto estético-filosófico que plantearon filósofos como Inmanuel Kant y Edmund Burke para pensar el arte romántico y, en el siglo XX, otros autores como Jean-François Lyotard, lo retomaron para analizar el arte de vanguardia. Así, lo sublime nos permite repensar la poética de Pizarnik en sus coincidencias y oposiciones a otras de la tradición moderna (como la de Charles Baudelaire o de las vanguardias latinoamericanas (como Oliverio Girondo y Vicente Huidobro.

  9. Fracture behavior of nuclear graphites under tensile impact loading

    International Nuclear Information System (INIS)

    Ugachi, Hirokazu; Ishiyama, Shintaro; Eto, Motokuni

    1994-01-01

    Impact tensile strength test was performed with two kinds of HTTR graphites, fine grained isotropic graphite, IG-11 and coarse grained near isotropic graphite, PGX and deformation and fracture behavior under the strain rate of over 100s -1 was measured and the following results were derived: (1) Tensile strength for IG-11 graphite does not depend on the strain rate less than 1 s -1 , but over 1 s -1 , tensile strength for IG-11 graphite increase larger than that measured under 1 s -1 . At the strain rate more than 100 s -1 , remarkable decrease of tensile strength for IG-11 graphite was found. Tensile strength of PGX graphite does not depend on the strain rate less than 1 s -1 , but beyond this value, the sharp tensile strength decrease occurs. (2) Under 100 s -1 , fracture strain for both graphites increase with increase of strain rate and over 100 s -1 , drastic increase of fracture strain for IG-11 graphite was found. (3) At the part of gage length, volume of specimen increase with increase of tensile loading level and strain rate. (4) Poisson's ratio for both graphites decrease with increase of tensile loading level and strain rate. (5) Remarkable change of stress-strain curve for both graphites under 100 s -1 was not found, but over 100 s -1 , the slope of these curve for IG-11 graphite decrease drastically. (author)

  10. Experimental modelling of plasma-graphite surface interaction in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Martynenko, Yu.V.; Guseva, M.I.; Gureev, V.M.; Danelyan, L.S.; Neumoin, V.E.; Petrov, V.B.; Khripunov, B.I.; Sokolov, Yu.A.; Stativkina, O.V.; Stolyarova, V.G. [Rossijskij Nauchnyj Tsentr ``Kurchatovskij Inst.``, Moscow (Russian Federation); Vasiliev, V.I.; Strunnikov, V.M. [TRINITI, Troizk (Russian Federation)

    1998-10-01

    The investigation of graphite erosion under normal operation ITER regime and disruption was performed by means of exposure of RGT graphite samples in a stationary deuterium plasma to a dose of 10{sup 22} cm{sup -2} and subsequent irradiation by power (250 MW/cm{sup 2}) pulse deuterium plasma flow imitating disruption. The stationary plasma exposure was carried out in the installation LENTA with the energy of deuterium ions being 200 eV at target temperatures of 770 C and 1150 C. The preliminary exposure in stationary plasma at temperature of physical sputtering does not essentially change the erosion due to a disruption, whereas exposure at the temperature of radiation enhanced sublimation dramatically increases the erosion due to disruption. In the latter case, the depth of erosion due to a disruption is determined by the depth of a layer with decreased strength. (orig.) 9 refs.

  11. Measuring Enthalpy of Sublimation of Volatiles by Means of Piezoelectric Crystal Microbalances

    Science.gov (United States)

    Dirri, Fabrizio; Palomba, Ernesto; Longobardo, Andrea; Zampetti, Emiliano

    2017-12-01

    Piezoelectric Crystal Microbalances (PCM's) are widely used to study the chemical processes involving volatile compounds in any environment, such as condensation process. Since PCM's are miniaturized sensor, they are very suitable for planetary in situ missions, where can be used to detect and to measure the mass amount of astrobiologically significant compounds, such as water and organics. This work focuses on the realization and testing of a new experimental setup, able to characterize volatiles which can be found in a planetary environment. In particular the enthalpy of sublimation of some dicarboxylic acids has been measured. The importance of dicarboxylic acids in planetology and astrobiology is due to the fact that they have been detected in carbonaceous chondritic material (e.g. Murchinson), among the most pristine material present in our Solar System. In this work, a sample of acid was heated in an effusion cell up to its sublimation. For a set of temperatures (from 30 °C to 75 °C), the deposition rate on the PCM surface has been measured. From these measurements, it has been possible to infer the enthalpy of sublimation of Adipic acid, i.e. ΔH = 141.6 ± 0.8 kJ/mol and Succinic acid, i.e. ΔH = 113.3 ± 1.3 kJ/mol. This technique has so demonstrated to be a good choice to recognise a single compound or a mixture (with an analysis upstream) even if some improvements concerning the thermal stabilization of the system will be implemented in order to enhance the results' accuracy. The experiment has been performed in support of the VISTA (Volatile In Situ Thermogravimetry Analyzer) project, which is included in the scientific payload of the ESA MarcoPolo-R mission study.

  12. Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2-C9 dicarboxylic acids

    Science.gov (United States)

    Dirri, F.; Palomba, E.; Longobardo, A.; Zampetti, E.

    2016-02-01

    We present here a novel experimental set-up that is able to measure the enthalpy of sublimation of a given compound by means of piezoelectric crystal microbalances (PCMs). The PCM sensors have already been used for space measurements, such as for the detection of organic and non-organic volatile species and refractory materials in planetary environments. In Earth atmospherics applications, PCMs can be also used to obtain some physical-chemical processes concerning the volatile organic compounds (VOCs) present in atmospheric environments. The experimental set-up has been developed and tested on dicarboxylic acids. In this work, a temperature-controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC recondensed onto the PCM quartz crystal, allowing the determination of the deposition rate. From the measurements of deposition rates, it has been possible to infer the enthalpy of sublimation of adipic acid, i.e. ΔHsub : 141.6 ± 0.8 kJ mol-1, succinic acid, i.e. 113.3 ± 1.3 kJ mol-1, oxalic acid, i.e. 62.5 ± 3.1 kJ mol-1, and azelaic acid, i.e. 124.2 ± 1.2 kJ mol-1. The results obtained show an accuracy of 1 % for succinic, adipic, and azelaic acid and within 5 % for oxalic acid and are in very good agreement with previous works (within 6 % for adipic, succinic, and oxalic acid and within 11 % or larger for azelaic acid).

  13. A graphite nanoeraser

    DEFF Research Database (Denmark)

    Liu, Ze; Bøggild, Peter; Yang, Jia-rui

    2011-01-01

    We present here a method for cleaning intermediate-size (up to 50 nm) contamination from highly oriented pyrolytic graphite and graphene. Electron-beam-induced deposition of carbonaceous material on graphene and graphite surfaces inside a scanning electron microscope, which is difficult to remove...... by conventional techniques, can be removed by direct mechanical wiping using a graphite nanoeraser, thus drastically reducing the amount of contamination. We discuss potential applications of this cleaning procedure....

  14. Graphite suspension in carbon dioxide

    International Nuclear Information System (INIS)

    Roche, R.

    1965-01-01

    Since 1963 the Atomic Division of SNECMA has been conducting, under a contract with the CEA, an experimental work with a two-component fluid comprised of carbon dioxide and small graphite particles. The primary purpose was the determination of basic engineering information pertaining to the stability and the flowability of the suspension. The final form of the experimental loop consists mainly of the following items: a light-phase compressor, a heavy-phase pump, an electrical-resistance type heater section, a cooling heat exchanger, a hairpin loop, a transparent test section and a separator. During the course of the testing, it was observed that the fluid could be circulated quite easily in a broad range of variation of the suspension density and velocity - density from 30 to 170 kg/m 3 and velocity from 2 to 24 m/s. The system could be restarted and circulation maintained without any difficulty, even with the heavy-phase pump alone. The graphite did not have a tendency to pack or agglomerate during operation. No graphite deposition was observed on the wall of the tubing. A long period run (250 hours) has shown the evolution of the particle dimensions. Starting with graphite of surface area around 20 m 2 /g (graphite particles about 1 μ), the powder surface area reaches an asymptotic value of 300 m 2 /g (all the particles less than 0.3 μ). Moisture effect on flow stability, flow distribution between two parallel channels, pressure drop in straight tubes, recompression ratio in diffusers were also investigated. (author) [fr

  15. Graphite structure and magnetic parameters of flake graphite cast iron

    Czech Academy of Sciences Publication Activity Database

    Vértesy, G.; Uchimoto, T.; Takagi, T.; Tomáš, Ivan; Kage, H.

    2017-01-01

    Roč. 442, Nov (2017), s. 397-402 ISSN 0304-8853 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:68378271 Keywords : magnetic NDE * magnetic adaptive testing * cast iron * graphite structure * pearlite content Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

  16. Low cost sic coated erosion resistant graphite

    International Nuclear Information System (INIS)

    Zafar, M.F.; Nicholls, J.R.

    2007-01-01

    The development of materials with unique and improved properties using low cost processes is essential to increase performance and reduce cost of the solid rocket motors. Specifically advancements are needed for boost phase nozzle. As these motors operate at very high pressure and temperatures, the nozzle must survive high thermal stresses with minimal erosion to maintain performance. Currently three material choices are being exploited; which are refractory metals, graphite and carbon-carbon composites. Of these three materials graphite is the most attractive choice because of its low cost, light weight, and easy forming. However graphite is prone to erosion, both chemical and mechanical, which may affect the ballistic conditions and mechanical properties of the nozzle. To minimize this erosion high density graphite is usually preferred; which is again very expensive. Another technique used to minimize the erosion is Pyrolytic Graphite (PG) coating inside the nozzle. However PG coating is prone to cracking and spallation along with very cumbersome deposition process. Another possible methodology to avoid this erosion is to convert the inside surface of the rocket nozzle to Silicon Carbide (SiC), which is very erosion resistant and have much better thermal stability compared to graphite and even PG. Due to its functionally gradient nature such a layer will be very adherent and resistant to spallation. The current research is focused on synthesizing, characterizing and oxidation testing of such a converted SiC layer on commercial grade graphite. (author)

  17. Method for producing dustless graphite spheres from waste graphite fines

    Science.gov (United States)

    Pappano, Peter J [Oak Ridge, TN; Rogers, Michael R [Clinton, TN

    2012-05-08

    A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

  18. Graphite targets at LAMPF

    International Nuclear Information System (INIS)

    Brown, R.D.; Grisham, D.L.

    1983-01-01

    Rotating polycrystalline and stationary pyrolytic graphite target designs for the LAMPF experimental area are described. Examples of finite element calculations of temperatures and stresses are presented. Some results of a metallographic investigation of irradiated pyrolytic graphite target plates are included, together with a brief description of high temperature bearings for the rotating targets

  19. Status of Chronic Oxidation Studies of Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert W. [Univ. of Tennessee, Knoxville, TN (United States)

    2016-05-01

    Graphite will undergo extremely slow, but continuous oxidation by traces of moisture that will be present, albeit at very low levels, in the helium coolant of HTGR. This chronic oxidation may cause degradation of mechanical strength and thermal properties of graphite components if a porous oxidation layer penetrates deep enough in the bulk of graphite components during the lifetime of the reactor. The current research on graphite chronic oxidation is motivated by the acute need to understand the behavior of each graphite grade during prolonged exposure to high temperature chemical attack by moisture. The goal is to provide the elements needed to develop predictive models for long-time oxidation behavior of graphite components in the cooling helium of HTGR. The tasks derived from this goal are: (1) Oxidation rate measurements in order to determine and validate a comprehensive kinetic model suitable for prediction of intrinsic oxidation rates as a function of temperature and oxidant gas composition; (2) Characterization of effective diffusivity of water vapor in the graphite pore system in order to account for the in-pore transport of moisture; and (3) Development and validation of a predictive model for the penetration depth of the oxidized layer, in order to assess the risk of oxidation caused damage of particular graphite grades after prolonged exposure to the environment of helium coolant in HTGR. The most important and most time consuming of these tasks is the measurement of oxidation rates in accelerated oxidation tests (but still under kinetic control) and the development of a reliable kinetic model. This report summarizes the status of chronic oxidation studies on graphite, and then focuses on model development activities, progress of kinetic measurements, validation of results, and improvement of the kinetic models. Analysis of current and past results obtained with three grades of showed that the classical Langmuir-Hinshelwood model cannot reproduce all

  20. The enthalpy of sublimation and thermodynamic functions of fermium

    International Nuclear Information System (INIS)

    Haire, R.G.; Gibson, J.K.

    1989-01-01

    The enthalpy of sublimation of fermium (Fm), element 100, has now been determined directly by measuring the partial pressure of Fm over alloys, for the temperature range of 642 to 905 K. The partial pressures were determined using Knudsen effusion and target collection techniques. Dilute (10 -5 --10 -7 atom %) solid alloys of Fm and mixtures of Fm and Es in both Sm and Yb solvents were studied. The presence of Es in two of the alloys allowed a direct comparison of the behavior of Fm and Es, where the latter could be used as a reference. It was possible to calculate enthalpies of sublimation and a hypothetical vapor pressure/temperature relationship for pure Fm metal by selecting Yb as the solvent most likely to form a nearly ideal alloy with Fm. From the experimental vapor pressure data, we derived average Second Law values of 33.8±3 kcal/mol and 23.5±3 cal/mol deg for the enthalpy and entropy of sublimation of Fm at 298 K. Third Law enthalpy values were also calculated using the experimental partial pressure data and entropies estimated from derived free energy functions and heat capacities for the solid and gaseous forms of Fm. The average Third Law values (34.8 kcal/mol and 25.1 cal/mol deg, respectively, at 298 K) are in agreement with those obtained via the Second Law. These results establish that Fm, like Es (element 99), is a divalent metal. The finding that Fm metal is the second divalent actinide element experimentally establishes the trend towards metallic divalency expected in the second half of the actinide series

  1. Study by electronic microscopy of corrosion features of graphite after hot oxidation (air, 620 C)

    International Nuclear Information System (INIS)

    Jodon de Villeroche, Suzanne

    1968-01-01

    The author reports the study of corrosion features of graphite after hot oxidation in the air at 620 C. It is based on observations made by electronic microscopy. This study comes after another one dedicated to oxidation features obtained by hot corrosion of natural graphite, and aims at comparing pyrolytic graphite before and after irradiation in an atomic pile, and at performing tests on a graphite processed with ozone. After a recall of generalities about natural graphite and of some issues related to hot corrosion of natural graphite, the author presents some characteristics and features of irradiated and non-irradiated pyrolytic graphite. He reports the study of the oxidation of samples of pyrolytic graphite: production of thin lamellae, production of glaze-carbon replicates, oxidation of irradiated and of non-irradiated graphite, healing of irradiation defects, and oxidation of ozone-processed natural graphite [fr

  2. Figure del desiderio: l'amore fra distruzione e sublime

    Directory of Open Access Journals (Sweden)

    Mabel Franzone

    2005-03-01

    Full Text Available Attraverso due racconti di Cortázar, l'analisi di due figure del desiderio ci permette esplorare due estremi seguendo una verticalità. La distruzione, doppio tenebroso della nostra anima, ci rivela un erotismo legato alla morte e al desiderio morboso di possedere l'Altro; il suo contraltare è un'ascesa vertiginosa accompagnata da un godimento estetico, dall'amore sublime prossimo all'esperienza mistica che si concluderà con una discesa progressiva e nel rispetto di questo Altro. La creazione letteraria si presenta come uno sfogo alle nostre angosce, che sono anche una sorta d'espressione dell'erotismo.

  3. Measured and modelled sublimation on the tropical Glaciar Artesonraju, Perú

    OpenAIRE

    M. Winkler; I. Juen; T. Mölg; G. Kaser

    2008-01-01

    Sublimation plays a decisive role in the surface energy balance of tropical glaciers. During the dry season low specific humidity and high surface roughness favour the direct transition from ice to vapour and drastically reduce the energy available for melting. However, field measurements are scarce and little is known about the performance of sublimation parametrisations in glacier mass balance and runoff models.

    During 15 days in August 2005 sublimation was measured on ...

  4. Asymptomatic Intracorneal Graphite Deposits following Graphite Pencil Injury

    OpenAIRE

    Philip, Swetha Sara; John, Deepa; John, Sheeja Susan

    2012-01-01

    Reports of graphite pencil lead injuries to the eye are rare. Although graphite is considered to remain inert in the eye, it has been known to cause severe inflammation and damage to ocular structures. We report a case of a 12-year-old girl with intracorneal graphite foreign bodies following a graphite pencil injury.

  5. Past, present, and future of sublimation transfer imaging

    Science.gov (United States)

    Akada, Masanori

    1990-07-01

    SONY's announcement of tlavica system shaked the world in 1981. In the new nonphotographic imaging system, image is acquired with CCD to be converted into electric image-signal, stored in magnetic recording media,displayed on a CR1 and printed on a special sheet. To get a hard copy, Sublimation Transfer technology was developed. That announcement brought about world-wide R&D of competitive color imaging systems: Ink-jet, Wax transfer,. Sublimation Transfer(ST) and Electrophotography. In spite of much effort,most of those were insufficient for getting a good hard copy. Developing sufficient ST recording media, Dai Nippon Printing started ST recording media business in 1986. It was the first manufacturing scale production and sale of ST recording media in the world. Nowadays ST technology is known for its advantages: high image quality, consistency from copy to copy, smooth tone-reproduction from high-light to maximum density, and easiness to use. In the following paper progress of ST recording media and the present situation and future markets of the media will be presented.

  6. Recent developments in graphite

    International Nuclear Information System (INIS)

    Cunningham, J.E.

    1983-01-01

    Overall, the HTGR graphite situation is in excellent shape. In both of the critical requirements, fuel blocks and support structures, adequate graphites are at hand and improved grades are sufficiently far along in truncation. In the aerospace field, GraphNOL N3M permits vehicle performance with confidence in trajectories unobtainable with any other existing material. For fusion energy applications, no other graphite can simultaneously withstand both extreme thermal shock and neutron damage. Hence, the material promises to create new markets as well as to offer a better candidate material for existing applications

  7. Graphite for fusion energy applications

    International Nuclear Information System (INIS)

    Eatherly, W.P.; Clausing, R.E.; Strehlow, R.A.; Kennedy, C.R.; Mioduszewski, P.K.

    1987-03-01

    Graphite is in widespread and beneficial use in present fusion energy devices. This report reflects the view of graphite materials scientists on using graphite in fusion devices. Graphite properties are discussed with emphasis on application to fusion reactors. This report is intended to be introductory and descriptive and is not intended to serve as a definitive information source

  8. Change in properties of graphite on stake of Obninsk NPP

    International Nuclear Information System (INIS)

    Virgul'ev, Yu.S.; Gundorov, V.V.; Kalyagina, I.P.; Belinskaya, N.T.; Dolgov, V.V.; Komissarov, O.V.; Stuzhnev, Yu.A.

    1997-01-01

    The results of testing the graphite from the AM-1 reactor masonry at the Obninsk NPP for its operation period are discussed. It is shown that the masonry graphite state after 42 years of the reactor operation remains satisfactory in the most cells inspected. Separate cells requiring a repair resulted from oxidation are characterized by strength decreased by several times. The laws of radiation changes in graphite properties are analyzed. The conclusion on possibility of the further masonry operation is drawn

  9. Carbon-14 Graphitization Chemistry

    Science.gov (United States)

    Miller, James; Collon, Philippe; Laverne, Jay

    2014-09-01

    Accelerator Mass Spectrometry (AMS) is a process that allows for the analysis of mass of certain materials. It is a powerful process because it results in the ability to separate rare isotopes with very low abundances from a large background, which was previously impossible. Another advantage of AMS is that it only requires very small amounts of material for measurements. An important application of this process is radiocarbon dating because the rare 14C isotopes can be separated from the stable 14N background that is 10 to 13 orders of magnitude larger, and only small amounts of the old and fragile organic samples are necessary for measurement. Our group focuses on this radiocarbon dating through AMS. When performing AMS, the sample needs to be loaded into a cathode at the back of an ion source in order to produce a beam from the material to be analyzed. For carbon samples, the material must first be converted into graphite in order to be loaded into the cathode. My role in the group is to convert the organic substances into graphite. In order to graphitize the samples, a sample is first combusted to form carbon dioxide gas and then purified and reduced into the graphite form. After a couple weeks of research and with the help of various Physics professors, I developed a plan and began to construct the setup necessary to perform the graphitization. Once the apparatus is fully completed, the carbon samples will be graphitized and loaded into the AMS machine for analysis.

  10. Melting temperature of graphite

    International Nuclear Information System (INIS)

    Korobenko, V.N.; Savvatimskiy, A.I.

    2001-01-01

    Full Text: Pulse of electrical current is used for fast heating (∼ 1 μs) of metal and graphite specimens placed in dielectric solid media. Specimen consists of two strips (90 μm in thick) placed together with small gap so they form a black body model. Quasy-monocrystal graphite specimens were used for uniform heating of graphite. Temperature measurements were fulfilled with fast pyrometer and with composite 2-strip black body model up to melting temperature. There were fulfilled experiments with zirconium and tungsten of the same black body construction. Additional temperature measurements of liquid zirconium and liquid tungsten are made. Specific heat capacity (c P ) of liquid zirconium and of liquid tungsten has a common feature in c P diminishing just after melting. It reveals c P diminishing after melting in both cases over the narrow temperature range up to usual values known from steady state measurements. Over the next wide temperature range heat capacity for W (up to 5000 K) and Zr (up to 4100 K) show different dependencies of heat capacity on temperature in liquid state. The experiments confirmed a high quality of 2-strip black body model used for graphite temperature measurements. Melting temperature plateau of tungsten (3690 K) was used for pyrometer calibration area for graphite temperature measurement. As a result, a preliminary value of graphite melting temperature of 4800 K was obtained. (author)

  11. Startup of a Joule-heated glass melter with a graphite slurry

    International Nuclear Information System (INIS)

    Allen, T.L.; Routt, K.R.; Porter, M.A.

    1983-01-01

    This paper discusses the theoretical equations and physical and electrical property data of various graphite slurries for starting up a glass melter. An application test is also included to demonstrate the graphite slurry startup technique

  12. Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L. [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Oliveira, A. N. [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); INMETRO, Av. Nossa Senhora das Graças, 50 25250-020 Duque de Caxias, RJ (Brazil); Li, M. S. [Instituto de Física de São Carlos, Universidade de São Paulo, Ave. Trabalhador São Carlense, 400, 13565-590 São Carlos, SP (Brazil)

    2015-07-15

    We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H{sub 2} are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.

  13. Uranium hexaflouride freezer/sublimer process simulator/trainer

    International Nuclear Information System (INIS)

    Carnal, C.L.; Belcher, J.D.; Tapp, P.A.; Ruppel, F.R.; Wells, J.C.

    1991-01-01

    This paper describes a software and hardware simulation of a freezer/sublimer unit used in gaseous diffusion processing of uranium hexafluoride (UF 6 ). The objective of the project was to build a plant simulator that reads control signals and produces plant signals to mimic the behavior of an actual plant. The model is based on physical principles and process data. Advanced Continuous Simulation Language (ACSL) was used to develop the model. Once the simulation was validated with actual plant process data, the ACSL model was translated into Advanced Communication and Control Oriented Language (ACCOL). A Bristol Babcock Distributed Process Controller (DPC) Model 3330 was the hardware platform used to host the ACCOL model and process the real world signals. The DPC will be used as a surrogate plant to debug control system hardware/software and to train operators to use the new distributed control system without disturbing the process. 2 refs., 4 figs

  14. Methods of conveying fluids and methods of sublimating solid particles

    Science.gov (United States)

    Turner, Terry D; Wilding, Bruce M

    2013-10-01

    A heat exchanger and associated methods for sublimating solid particles therein, for conveying fluids therethrough, or both. The heat exchanger includes a chamber and a porous member having a porous wall having pores in communication with the chamber and with an interior of the porous member. A first fluid is conveyed into the porous member while a second fluid is conveyed into the porous member through the porous wall. The second fluid may form a positive flow boundary layer along the porous wall to reduce or eliminate substantial contact between the first fluid and the interior of the porous wall. The combined first and second fluids are conveyed out of the porous member. Additionally, the first fluid and the second fluid may each be conveyed into the porous member at different temperatures and may exit the porous member at substantially the same temperature.

  15. Graphite oxidation and structural strength of graphite support column in VHTR

    International Nuclear Information System (INIS)

    Park, Byung Ha; No, Hee Cheno; Kim, Eung Soo; Oh, Chang H.

    2009-01-01

    The air-ingress event by a large pipe break is an important accident considered in design of very high-temperature gas-cooled reactors (VHTR). Core-collapse prediction is a main safety issue. Structural failure model are technically required. The objective of this study is to develop structural failure model for the supporting graphite material in the lower plenum of the GT-MHR (gas-turbine-modular high temperature reactor). Graphite support column is important for VHTR structural integrity. Graphite support columns are under the axial load. Critical strength of graphite column is related to slenderness ratio and bulk density. Through compression tests for fresh and oxidized graphite columns we show that compressive strength of IG-110 was 79.46 MPa. And, the buckling strength of IG-110 column was expressed by the empirical formula: σ 0 =σ straight-line - C L/r, σ straight-line =91.31 MPa, C=1.01. The results of uniform and non-uniform oxidation tests show that the strength degradation of oxidized graphite column is expressed in the following non-dimensional form: σ/σ 0 =exp(-kd), k=0.111. Also, from the results of the uniform oxidation test with a complicated-shape column, we found out that the above non-dimensional equation obtained from the uniform oxidation test is applicable to a uniform oxidation case with a complicated-shape column. (author)

  16. Graphite structure and its relation to mechanical engineering design

    International Nuclear Information System (INIS)

    Brocklehurst, J.E.; Kelly, B.T.

    1980-01-01

    The inhomogeneous nature of polycrystalline graphite requires property measurements to be made over dimensions large enough to average the local variations in the structure. This is particularly true for mechanical integrity, and experimental data are presented which illustrate the importance of the real aggregate structure of graphite and the difficulties of interpreting strength data from different tests. The classical statistical treatments do not hold generally, and the problem of defining a failure criterion for graphite is discussed. It is suggested that the stress conditions in graphite components might be classified in terms of the dimensions and stress gradients related to the characteristic flaw size of the material as determined experimentally. (author)

  17. Calculational criticality analyses of 10- and 20-MW UF6 freezer/sublimer vessels

    International Nuclear Information System (INIS)

    Jordan, W.C.

    1993-02-01

    Calculational criticality analyses have been performed for 10- and 20-MW UF 6 freezer/sublimer vessels. The freezer/sublimers have been analyzed over a range of conditions that encompass normal operation and abnormal conditions. The effects of HF moderation of the UF 6 in each vessel have been considered for uranium enriched between 2 and 5 wt % 235 U. The results indicate that the nuclearly safe enrichments originally established for the operation of a 10-MW freezer/sublimer, based on a hydrogen-to-uranium moderation ratio of 0.33, are acceptable. If strict moderation control can be demonstrated for hydrogen-to-uranium moderation ratios that are less than 0.33, then the enrichment limits for the 10-MW freezer/sublimer may be increased slightly. The calculations performed also allow safe enrichment limits to be established for a 20-NM freezer/sublimer under moderation control

  18. A Low Cost Inflatable CubeSat Drag Brake Utilizing Sublimation

    Science.gov (United States)

    Horn, Adam Charles

    The United Nations Inter-Agency Debris Coordination Committee has adopted a 25-year post-mission lifetime requirement for any satellite orbiting below 2000 km in order to mitigate the growing orbital debris threat. Low-cost CubeSats have become important satellite platforms with startling capabilities, but this guideline restricts them to altitudes below 600 km because they remain in orbit too long. In order to enable CubeSat deployments at higher release altitudes, a low-cost, ultra-reliable deorbit device is needed. This thesis reports on efforts to develop a deployable and passively inflatable drag brake that can deorbit from higher orbital altitudes, thereby complying with the 25-year orbital lifetime guideline. On the basis of concepts first implemented during the NASA Echo Satellite Project, this study investigated the design of an inflatable CubeSat drag device that utilizes sublimating benzoic acid powder as the inflation propellant. Testing has focused on demonstrating the functionality of charging a Mylar drag brake bladder with appropriate quantities of benzoic acid powder, and the exposure to a controlled-temperature vacuum chamber causing the bladder to inflate. Although results show a measureable increase in internal pressure when introduced to anticipated orbital temperatures, a significant air-derived expansion prior to sublimation was encountered due to the undetectable volume of ambient residual air in the fabricated membrane bladders. These tests have demonstrated the feasibility of this approach, thereby demonstrating that this concept can create a potentially smaller and less expensive drag device, eliminating inflation gas tanks and valves. In that way, this system can provide a low-cost, miniaturized system that reduces a CubeSat's orbital lifetime to less than 25 years, when placed at higher orbital altitude.

  19. Nuclear graphite ageing and turnaround

    International Nuclear Information System (INIS)

    Marsden, B.J.; Hall, G.N.; Smart, J.

    2001-01-01

    Graphite moderated reactors are being operated in many countries including, the UK, Russia, Lithuania, Ukraine and Japan. Many of these reactors will operate well into the next century. New designs of High Temperature Graphite Moderated Reactors (HTRS) are being built in China and Japan. The design life of these graphite-moderated reactors is governed by the ageing of the graphite core due to fast neutron damage, and also, in the case of carbon dioxide cooled reactors by the rate of oxidation of the graphite. Nuclear graphites are polycrystalline in nature and it is the irradiation-induced damage to the individual graphite crystals that determines the material property changes with age. The life of a graphite component in a nuclear reactor can be related to the graphite irradiation induced dimensional changes. Graphites typically shrink with age, until a point is reached where the shrinkage stops and the graphite starts to swell. This change from shrinkage to swelling is known as ''turnaround''. It is well known that pre-oxidising graphite specimens caused ''turnaround'' to be delayed, thus extending the life of the graphite, and hence the life of the reactor. However, there was no satisfactory explanation of this behaviour. This paper presents a numerical crystal based model of dimensional change in graphite, which explains the delay in ''turnaround'' in the pre-oxidised specimens irradiated in a fast neutron flux, in terms of crystal accommodation and orientation and change in compliance due to radiolytic oxidation. (author)

  20. Characteristics of first loaded IG-110 graphite in HTTR core

    International Nuclear Information System (INIS)

    Sumita, Junya; Shibata, Taiju; Iyoku, Tatsuo; Sawa, Kazuhiro; Hanawa, Satoshi; Ishihara, Masahiro

    2006-10-01

    IG-110 graphite is a fine-grained isotropic and nuclear-grade graphite with excellent resistivity on both irradiation and corrosion and with high strength. The IG-110 graphite is used for the graphite components of High Temperature Engineering Test Reactor (HTTR) such as fuel and control rod guide blocks and support posts. In order to design and fabricate the graphite components in the HTTR, the Japan Atomic Energy Research Institute (the Japan Atomic Energy Agency at present) had established the graphite structural design code and design data on the basis of former research results. After the design code establishment, the IG-110 graphite components were fabricated and loaded in the HTTR core. This report summarized the characteristics of the first loaded IG-110 graphite as basic data for surveillance test, measuring material characteristics changed by neutron irradiation and oxidation. By comparing the design data, it was shown that the first loaded IG-110 graphite had excellent strength properties and enough safety margins to the stress limits in the design code. (author)

  1. A systematic study of acoustic emission from nuclear graphites

    International Nuclear Information System (INIS)

    Neighbour, G.B.; McEnaney, B.

    1996-01-01

    Acoustic emission (AE) monitoring has been identified as a possible method to determine internal stresses in nuclear graphites using the Kaiser effect, i.e., on stressing a graphite that has been subject to a prior stress, the onset of AE occurs at the previous peak stress. For three nuclear graphites (PGA, IM1-24 and VNEC), AE was monitored during both monotonic and cyclic loading to failure in tensile, compressive and flexural test modes. For unirradiated graphites, the Kaiser effect was not found in cyclic loading, but a Felicity effect was observed, i.e., the onset of AE occurred below the previously applied peak stress. The Felicity effect was attributed to time-dependent relaxation and recovery processes and was characterized using a new parameter, the Recovery ratio. It was shown that AE can be used to monitor creep strain and creep recovery in graphites at zero load. The AE-time responses from these experiments were fitted to equations similar to those used for creep strain-time at elevated temperatures. The number of AE counts from irradiated graphites were greater than those from unirradiated graphites, subject to similar stresses, due to increases in porosity caused by radiolytic oxidation. A Felicity effect was also observed on cyclic loading of irradiated graphites, but no evidence for a Kaiser effect was found for irradiated graphites loaded monotonically to failure. Thus internal stresses in irradiated graphites could not be measured using AE. This was attributed to relaxation and recovery processes that occur between removing the irradiated graphite from the reactor and AE testing. This work indicated that AE monitoring is not a suitable technique for measuring internal stresses in irradiated graphite. (author). 19 refs, 6 figs, 6 tabs

  2. Recompressed exfoliated graphite articles

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2013-08-06

    This invention provides an electrically conductive, less anisotropic, recompressed exfoliated graphite article comprising a mixture of (a) expanded or exfoliated graphite flakes; and (b) particles of non-expandable graphite or carbon, wherein the non-expandable graphite or carbon particles are in the amount of between about 3% and about 70% by weight based on the total weight of the particles and the expanded graphite flakes combined; wherein the mixture is compressed to form the article having an apparent bulk density of from about 0.1 g/cm.sup.3 to about 2.0 g/cm.sup.3. The article exhibits a thickness-direction conductivity typically greater than 50 S/cm, more typically greater than 100 S/cm, and most typically greater than 200 S/cm. The article, when used in a thin foil or sheet form, can be a useful component in a sheet molding compound plate used as a fuel cell separator or flow field plate. The article may also be used as a current collector for a battery, supercapacitor, or any other electrochemical cell.

  3. Electrochemical Ultracapacitors Using Graphitic Nanostacks

    Science.gov (United States)

    Marotta, Christopher

    2012-01-01

    Electrochemical ultracapacitors (ECs) have been developed using graphitic nanostacks as the electrode material. The advantages of this technology will be the reduction of device size due to superior power densities and relative powers compared to traditional activated carbon electrodes. External testing showed that these materials display reduced discharge response times compared to state-of-the-art materials. Such applications are advantageous for pulsed power applications such as burst communications (satellites, cell phones), electromechanical actuators, and battery load leveling in electric vehicles. These carbon nanostructures are highly conductive and offer an ordered mesopore network. These attributes will provide more complete electrolyte wetting, and faster release of stored charge compared to activated carbon. Electrochemical capacitor (EC) electrode materials were developed using commercially available nanomaterials and modifying them to exploit their energy storage properties. These materials would be an improvement over current ECs that employ activated carbon as the electrode material. Commercially available graphite nanofibers (GNFs) are used as precursor materials for the synthesis of graphitic nanostacks (GNSs). These materials offer much greater surface area than graphite flakes. Additionally, these materials offer a superior electrical conductivity and a greater average pore size compared to activated carbon electrodes. The state of the art in EC development uses activated carbon (AC) as the electrode material. AC has a high surface area, but its small average pore size inhibits electrolyte ingress/egress. Additionally, AC has a higher resistivity, which generates parasitic heating in high-power applications. This work focuses on fabricating EC from carbon that has a very different structure by increasing the surface area of the GNF by intercalation or exfoliation of the graphitic basal planes. Additionally, various functionalities to the GNS

  4. Graphite-based extinguishants for liquid metal fires

    International Nuclear Information System (INIS)

    Simpson, J.M.; Gardener, N.J.L.

    1987-01-01

    Effective extinguishants for liquid alkali metal fires must be provided for all LMFBRs. Traditional sodium salt based extinguishants have disadvantages. An intercalation compound of graphite was identified as a possible alternative. Following successful tests on fires of up to 25 m 2 area the graphite based extinguishant has been introduced by the UKAEA at Dounreay. (author)

  5. Bromine intercalated graphite for lightweight composite conductors

    KAUST Repository

    Amassian, Aram; Patole, Archana

    2017-01-01

    A method of fabricating a bromine-graphite/metal composite includes intercalating bromine within layers of graphite via liquid-phase bromination to create brominated-graphite and consolidating the brominated-graphite with a metal nanopowder via a

  6. Surface coating of graphite pebbles for Korean HCCR TBM

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngmin [National Fusion Research Institute, Daejeon (Korea, Republic of); Yun, Young-Hoon, E-mail: yunh2@dsu.ac.kr [Dongshin University, Naju (Korea, Republic of); Park, Yi-Hyun; Ahn, Mu-Young; Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Highlights: • A CVR-SiC coating was successfully formed on graphite pebbles for neutron reflector. • Dense and fine-grained surface morphologies of the SiC coatings were observed. • Oxidation resistance of the CVR-SiC-coated graphite pebbles was improved. - Abstract: The new concept of the recently modified Helium-Cooled Ceramic Reflector (HCCR) Test Blanket Module (TBM) is to adopt a graphite reflector in the form of a pebble bed. A protective SiC coating is applied to the graphite pebbles to prohibit their reaction with steam or air as well as dust generation during TBM operation. In this research, the chemical vapor reaction (CVR) method was applied to fabricate SiC-coated graphite pebbles in a silica source. Relatively dense CVR-SiC coating was successfully formed on the graphite pebbles through the reduction of the graphite phase with SiO gas that was simply created from the silica source at 1850 °C (2 h). The microstructural features, XRD patterns, pore-size distribution and oxidation behavior of the SiC-coated graphite pebbles were investigated. To develop the practical process, which will be applied for mass production hereafter, a novel alternative method was applied to form the layer of SiC coating on the graphite pebbles over the silica source.

  7. Graphite moderator lifecycle behaviour. Proceedings of a specialists meeting

    International Nuclear Information System (INIS)

    1996-08-01

    The meeting provided the forum for graphite specialists representing operating and research organizations worldwide to exchange information in the following areas: the status of graphite development; operation and safety procedures for existing and future graphite moderated reactors; graphite testing techniques; review of the experiences gained and data acquired on the influence of neutron irradiation and oxidizing conditions on key graphite properties; and to exchange information useful for decommissioning activities. The participants provided twenty-seven papers on behalf of their countries and respective technical organizations. An open discussion followed each of the presentations. A consistently reoccurring theme throughout the specialists meeting was the noticeable reduction in the number of graphite experts remaining the nuclear power industry. Graphite moderated power reactors have provided a significant contribution to the generation of electricity throughout the past forty years and will continue to be a prominent energy source for the future. Yet, many of the renowned experts in the field of nuclear graphites are nearing the end of their careers without apparent replacement. This, coupled with changes in the focus on nuclear power by some industrialized countries, has prompted the IAEA to initiate an evaluation on the feasibility and interest by Member States of establishing a central archive facility for the storage of data on irradiated graphites. Refs, figs, tabs

  8. A study on wear behaviour of Al/6101/graphite composites

    Directory of Open Access Journals (Sweden)

    Pardeep Sharma

    2017-03-01

    Full Text Available The current research work scrutinizes aluminium alloy 6101-graphite composites for their mechanical and tribological behaviour in dry sliding environments. The orthodox liquid casting technique had been used for the manufacturing of composite materials and imperilled to T6 heat treatment. The content of reinforcement particles was taken as 0, 4, 8, 12 and 16 wt.% of graphite to ascertain it is prospective as self-lubricating reinforcement in sliding wear environments. Hardness, tensile strength and flexural strength of cast Al6101 metal matrix and manufactured composites were evaluated. Hardness, tensile strength and flexural strength decreases with increasing volume fraction of graphite reinforcement as compared to cast Al6101 metal matrix. Wear tests were performed on pin on disc apparatus to assess the tribological behaviour of composites and to determine the optimum volume fraction of graphite for its minimum wear rate. Wear rate reduces with increase in graphite volume fraction and minimum wear rate was attained at 4 wt.% graphite. The wear was found to decrease with increase in sliding distance. The average co-efficient of friction also reduces with graphite addition and its minimum value was found to be at 4 wt.% graphite. The worn surfaces of wear specimens were studied through scanning electron microscopy. The occurrence of 4 wt.% of graphite reinforcement in the composites can reveal loftier wear possessions as compared to cast Al6101 metal matrix.

  9. Preparation of in-house graphite reference material for boron

    International Nuclear Information System (INIS)

    Kumar, Sanjukta A.; Venkatesh, K.; Swain, Kallola K.; Manisha, V.; Kamble, Granthali S.; Pandey, Shailaja P.; Remya Devi, P.S.; Ghosh, M.; Verma, R.

    2016-05-01

    Graphite is extensively used in nuclear technology. Boron concentration in graphite is one of the important parameters that decide its acceptability for nuclear applications. Reliable analytical methods are essential for the determination of boron in graphite at concentration about 5 mg kg -1 . Reference materials are used for validation of existing analytical methods and developing new methodologies. In view of the importance of determination of boron in graphite and unavailability of graphite reference material, an In-house graphite reference material was prepared in Analytical Chemistry Division. Graphite source material was procured, processed to obtain powder of ≤ 75 μm (200 mesh) and bottled. Procedures were developed for the determination of boron in graphite using inductively coupled plasma optical emission spectrometry (ICPOES) and inductively coupled plasma mass spectrometry (ICPMS) techniques. Homogeneity testing was carried out on the bottled units and boron content along with the combined and expanded uncertainties were established. The assigned boron concentration in the In-house graphite reference material is (7.3±0.46) mg kg -1 . (author)

  10. Graphite moderator lifecycle behaviour. Proceedings of a specialists meeting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    The meeting provided the forum for graphite specialists representing operating and research organizations worldwide to exchange information in the following areas: the status of graphite development; operation and safety procedures for existing and future graphite moderated reactors; graphite testing techniques; review of the experiences gained and data acquired on the influence of neutron irradiation and oxidizing conditions on key graphite properties; and to exchange information useful for decommissioning activities. The participants provided twenty-seven papers on behalf of their countries and respective technical organizations. An open discussion followed each of the presentations. A consistently reoccurring theme throughout the specialists meeting was the noticeable reduction in the number of graphite experts remaining the nuclear power industry. Graphite moderated power reactors have provided a significant contribution to the generation of electricity throughout the past forty years and will continue to be a prominent energy source for the future. Yet, many of the renowned experts in the field of nuclear graphites are nearing the end of their careers without apparent replacement. This, coupled with changes in the focus on nuclear power by some industrialized countries, has prompted the IAEA to initiate an evaluation on the feasibility and interest by Member States of establishing a central archive facility for the storage of data on irradiated graphites. Refs, figs, tabs.

  11. Surface coating of graphite pebbles for Korean HCCR TBM

    International Nuclear Information System (INIS)

    Lee, Youngmin; Yun, Young-Hoon; Park, Yi-Hyun; Ahn, Mu-Young; Cho, Seungyon

    2014-01-01

    Highlights: • A CVR-SiC coating was successfully formed on graphite pebbles for neutron reflector. • Dense and fine-grained surface morphologies of the SiC coatings were observed. • Oxidation resistance of the CVR-SiC-coated graphite pebbles was improved. - Abstract: The new concept of the recently modified Helium-Cooled Ceramic Reflector (HCCR) Test Blanket Module (TBM) is to adopt a graphite reflector in the form of a pebble bed. A protective SiC coating is applied to the graphite pebbles to prohibit their reaction with steam or air as well as dust generation during TBM operation. In this research, the chemical vapor reaction (CVR) method was applied to fabricate SiC-coated graphite pebbles in a silica source. Relatively dense CVR-SiC coating was successfully formed on the graphite pebbles through the reduction of the graphite phase with SiO gas that was simply created from the silica source at 1850 °C (2 h). The microstructural features, XRD patterns, pore-size distribution and oxidation behavior of the SiC-coated graphite pebbles were investigated. To develop the practical process, which will be applied for mass production hereafter, a novel alternative method was applied to form the layer of SiC coating on the graphite pebbles over the silica source

  12. Cesium diffusion in graphite

    International Nuclear Information System (INIS)

    Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

    1980-05-01

    Experiments on diffusion of 137 Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of 137 Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000 0 C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ΔE of the equation D/epsilon = (D/epsilon) 0 exp [-ΔE/RT] are about 4 x 10 -2 cm 2 /s and 30 kcal/mole, respectively

  13. Intercomparison of graphite irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Hering, H; Perio, P; Seguin, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    While fast neutrons only are effective in damaging graphite, results of irradiations are more or less universally expressed in terms of thermal neutron fluxes. This paper attempts to correlate irradiations made in different reactors, i.e., in fluxes of different spectral compositions. Those attempts are based on comparison of 1) bulk length change and volume expansion, and 2) crystalline properties (e.g., lattice parameter C, magnetic susceptibility, stored energy, etc.). The methods used by various authors for determining the lattice constants of irradiated graphite are discussed. (author)

  14. High heat flux experiment on isotropic graphite using pulsed laser beam

    International Nuclear Information System (INIS)

    Kizaki, Hiroshi; Tokunaga, Kazutoshi; Fukuda, Shigehisa; Yoshida, Naoaki; Muroga, Takeo.

    1989-01-01

    In order to examine the plasma-withstanding behavior of isotropic graphite which is the leading favorite material for the first wall of nuclear fusion reactors, the pulsed thermal loading experiment was carried out by using a laser. As the result of analyzing the gas which was emitted during the pulsed thermal loading, together with the formation and release of various hydrocarbon gases, also the formation of carbon clusters due to the sublimation of carbon was observed. The vacuum characteristics and the dependence on thermal loading condition and surface treatment condition of these released gases were determined, and the problems and the way of improvement in its application to nuclear fusion reactors were elucidated. Since the isotropic graphite is of low atomic number, the radiation loss in plasma is small, and the improvement of the plasma parameters can be expected. Besides, the heat resistance and high temperature stability in vacuum are good, and the induced radioactivity is low. On the other hand, the quantity of gas occlusion is much, various hydrocarbon gases are formed at high temperature, and the wear due to sublimation arises by very high thermal loading. The experimental method, the observation of graphite surface by SEM, and the effect of carbon coating due to thermal decomposition are reported. (K.I.)

  15. On the use of semiempirical models of (solid + supercritical fluid) systems to determine solid sublimation properties

    International Nuclear Information System (INIS)

    Tabernero, Antonio; Martin del Valle, Eva M.; Galan, Miguel A.

    2011-01-01

    Research highlights: → We propose a method to determine sublimation properties of solids. → Low deviations were produced calculating sublimation enthalpies and pressures. → It is a required step to determine the vaporization enthalpy of the solid. → It is possible to determine solid properties using semiempirical models solid-SCF. - Abstract: Experimental solubility data of solid-supercritical fluids have significantly increased in the last few years, and semiempirical models are emerging as one of the best choices to fit this type of data. This work establishes a methodology to calculate sublimation pressures using this type of equations. It requires the use of Bartle's equation to model equilibria data solid-supercritical fluids with the aim of determining the vaporization enthalpy of the compound. Using this method, low deviations were obtained by calculating sublimation pressures and sublimation enthalpies. The values of the sublimation pressures were subsequently used to successfully model different multiphasic equilibria, as solid-supercritical fluids and solid-solvent-supercritical fluids with the Peng-Robinson equation of state (without considering the sublimation pressure as an adjustable parameter). On the other hand, the sublimation pressures were also used to calculate solid sublimation properties and acetaminophen solvation properties in some solvents. Also, solubility data solid-supercritical fluids from 62 pharmaceuticals were fitted with different semiempirical equations (Chrastil, Kumar-Johnston and Bartle models) in order to present the values of solvation enthalpies in sc-CO 2 and vaporization enthalpies for these compounds. All of these results highlight that semiempirical models can be used for any other purpose as well as modeling (solid + supercritical fluids) equilibria.

  16. Graphite-based photovoltaic cells

    Science.gov (United States)

    Lagally, Max; Liu, Feng

    2010-12-28

    The present invention uses lithographically patterned graphite stacks as the basic building elements of an efficient and economical photovoltaic cell. The basic design of the graphite-based photovoltaic cells includes a plurality of spatially separated graphite stacks, each comprising a plurality of vertically stacked, semiconducting graphene sheets (carbon nanoribbons) bridging electrically conductive contacts.

  17. Mass spectrometry study of sublimation of rare earth acetylacetonate adducts with hexamethylphosphorustriamide

    International Nuclear Information System (INIS)

    Kuz'mina, N.P.; Semyannikov, P.P.; Martynenko, L.I.; Ch'eu Tkhi Nguet; AN SSSR, Novosibirsk

    1991-01-01

    Process of vacuum sublimation of MA 3 ·Q adducts (M=Nd,Ho,Er; A - -acetylacetonate-ion; Q-hexamethylphosphorustriamide) was studied by mass-spectrometry method. Composinion of gaseous phase, formed in 20-140 deg C range at 10 -5 mm Hg, was determined. Scheme of MA 3 ·Q sublimation, including Q splitting and transition of MA 3 ·Q adducts and MA 3 and Q products of their thermodestruction to gaseous phase, was suggested. ΔH values of MA 3 ·Q thermodestruction and MA 3 sublimation were calculated

  18. The oxidation kinetics for sublimates formed during niobium electron-beam remelting

    International Nuclear Information System (INIS)

    Chumarev, V.M.; Gulyaeva, R.I.; Mar'evich, V.P.; Upolovnikova, A.G.; Udoeva, L.Yu.

    2003-01-01

    The oxidation of sublimates of Nb-Al electron beam remelting is investigated under conditions of isothermal and continuous heating in the air. It is stated that basic oxidation products are niobium and aluminium oxides, as well as aluminium niobates of variable composition of Al 2 O 3 · mNb 2 O 5 . The more aluminium enriched sublimates possess an increased resistance to oxidation. Formed in sublimates NbAl 3 intermetallic compound features the highest heat resistance. Oxidation parameters are determined by the method of nonisothermic kinetics. It is noted that the running processes exhibit a multistage nature and are limited by internal diffusion [ru

  19. Debate on sublime in the end of 18th century: Burke, Kant, Schiller

    Directory of Open Access Journals (Sweden)

    Jeremić-Molnar Dragana

    2009-01-01

    Full Text Available In the article the authors are examining three positions within the 18th Century aesthetic discussion on the sublime - Edmund Burke's, Immanuel Kant's and Friedrich Schiller's. They are also trying to reconstruct the political backgrounds of each of this theoretical positions: old regime conservatism (Burke, republican liberalism (Schiller and romantic longing for the 'third way' (Kant. The most sophisticated and mature theory of sublime is found in Schiller's aesthetic works, especially in those following his disappointment in French Revolution, in which the relationship between sublime and paradoxes of historical violence is most thoroughly reflected.

  20. Graphite target for the spiral project

    International Nuclear Information System (INIS)

    Putaux, J.C.; Ducourtieux, M.; Ferro, A.; Foury, P.; Kotfila, L.; Mueller, A.C.; Obert, J.; Pauwels, N.; Potier, J.C.; Proust, J.; Loiselet, M.

    1996-01-01

    A study of the thermal and physical properties of graphite targets for the SPIRAL project is presented. The main objective is to develop an optimized set-up both mechanically and thermally resistant, presenting good release properties (hot targets with thin slices). The results of irradiation tests concerning the mechanical and thermal resistance of the first prototype of SPIRAL target with conical geometry are presented. The micro-structural properties of the graphite target is also studied, in order to check that the release properties are not deteriorated by the irradiation. Finally, the results concerning the latest pilot target internally heated by an electrical current are shown. (author)

  1. Bion and the sublime: the origins of an aesthetic paradigm.

    Science.gov (United States)

    Civitarese, Giuseppe

    2014-12-01

    In constructing his theory Bion drew on a number of symbolic matrices: psychoanalysis, philosophy, mathematics, literature, aesthetics. The least investigated of these is the last. True, we know that Bion cites many authors of the Romantic period, such as Coleridge, Keats, Blake and Wordsworth, as well as others who were held in high esteem in the Romantic period, such as Milton. However, less is known about the influence exerted on him by the aesthetics of the sublime, which while chronologically preceding Romanticism is in fact one of its components. My working hypothesis is that tracing a number of Bion's concepts back to this secret model can serve several purposes: firstly, it contributes to the study of the sources, and, secondly, it makes these concepts appear much less occasional and idiosyncratic than we might believe, being as they are mostly those less immediately understandable but not less important (O, negative capability, nameless dread, the infinite, the language of achievement, unison etc.). Finally, connecting these notions to a matrix, that is, disclosing the meaning of elements that are not simply juxtaposed but dynamically interrelated, in my view significantly increases not only their theoretical intelligibility but also their usefulness in clinical practice. In conclusion, one could legitimately argue that Bion gradually subsumed all the other paradigms he drew on within the aesthetic paradigm. Copyright © 2014 Institute of Psychoanalysis.

  2. Nuclear graphite wear properties and estimation of graphite dust production in HTR-10

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xiaowei, E-mail: xwluo@tsinghua.edu.cn; Wang, Xiaoxin; Shi, Li; Yu, Xiaoyu; Yu, Suyuan

    2017-04-15

    Highlights: • Graphite dust. • The wear properties of graphite. • Pebble bed. • High Temperature Gas-cooled Reactor. • Fuel element. - Abstract: The issue of the graphite dust has been a research focus for the safety of High Temperature Gas-cooled Reactors (HTGRs), especially for the pebble bed reactors. Most of the graphite dust is produced from the wear of fuel elements during cycling of fuel elements. However, due to the complexity of the motion of the fuel elements in the pebble bed, there is no systematic method developed to predict the amount the graphite dust in a pebble bed reactor. In this paper, the study of the flow of the fuel elements in the pebble bed was carried out. Both theoretical calculation and numerical analysis by Discrete Element Method (DEM) software PFC3D were conducted to obtain the normal forces and sliding distances of the fuel elements in pebble bed. The wearing theory was then integrated with PFC3D to estimate the amount of the graphite dust in a pebble bed reactor, 10 MW High Temperature gas-cooled test Reactor (HTR-10).

  3. Technical development of graphite waste treatment in NUPEC

    International Nuclear Information System (INIS)

    Saishu, S.; Inoue, T.

    2001-01-01

    In Japan, Tokai Power Station, which is a Gas Cooled Reactor and uses graphite as moderator, ceased operation at the end of March in 1998 and it is planned to transfer to decommissioning stage. In this decommissioning stage it is very important to be able to treat and dispose the graphite waste in order to carry out the decommissioning safely and economically. NUPEC has been developing the graphite treatment and disposal technology since 1997 and we introduce the outline of the technical development. For the technology on high density packing into disposal container, the high density packing method and the assessment method on nuclide leaching characteristics were developed, and the cementing test for graphite powder by using Tokai spare graphite was performed and the hydrophobic characteristics between graphite and cement was grasped and the accelerator candidature for affinity was selected. From the view point of economical treatment, the incinerating technology was selected as candidature, and the methods for incinerating graphite and treating off gas are developed. The method of collecting C-14 in off gas was selected for reducing the off gas radiation level. The applicability of actual graphite treatment technology was considered from the view point of safety, economics and preparation of technical standard; the technical theme appeared, the developing planning items were established, and the detailed and actual scale tests will be carried out according to the planning. (author)

  4. Rate-dependent mode I interlaminar crack growth mechanisms in graphite/epoxy and graphite/PEEK

    Science.gov (United States)

    Gillespie, J. W., Jr.; Carlsson, L. A.; Smiley, A. J.

    1987-01-01

    In this paper the mode I fracture behavior of graphite/epoxy and graphite/PEEK composites is examined over four decades of crosshead rates (0.25-250 mm/min). Straight-sided double-cantilever-beam specimens consisting of unidirectional laminates were tested at room temperature. For graphite/epoxy the load-deflection response was linear to fracture, and stable slow crack growth initiating at the highest load level was observed for all rates tested. In contrast, mode I crack growth in the graphite/PEEK material was often unstable and showed stick-slip behavior. Subcritical crack growth occurring prior to the onset of fracture was observed at intermediate displacement rates. A mechanism for the fracture behavior of the graphite/PEEK material (based on viscoelastic, plastic, and microcrack coalescence in the process zone) is proposed and related to the observed rate-dependent phenomena.

  5. Mimeses do sublime: a recepção de Kant pelo Romantismo e pelo Expressionismo Mimesis of sublime: the Romantism and Expressionism reception of Kant

    Directory of Open Access Journals (Sweden)

    Priscila Rossinetti Rufinoni

    2007-01-01

    Full Text Available Partindo das analises do criticismo kantiano, este texto investiga as concepções romântica e moderna de sublime e de imaginação. Se, por um lado, a concepção romântica inaugura o mundo moderno, por outro, a expressionista mostra os limites dessa mesma modernidade. Para ambas, entretanto, a Crítica do Juízo de Kant é o âmbito privilegiado no qual podemos precisar as distinções.Starting from the analysis of the Kantian criticism, this text investigates the romantic and the modern conceptions of sublime and imagination. On the one hand, the romantic conceptions of sublime inaugurate the modern world. On the other hand, the expressionist conceptions show the confines of this world. The Critique of Judgment is the very locus where such distinctions can be drawn with precision.

  6. Electronic properties of graphite

    International Nuclear Information System (INIS)

    Schneider, J.

    2010-10-01

    In this thesis, low-temperature magneto-transport (T ∼ 10 mK) and the de Haas-van Alphen effect of both natural graphite and highly oriented pyrolytic graphite (HOPG) are examined. In the first part, low field magneto-transport up to B = 11 T is discussed. A Fourier analysis of the background removed signal shows that the electric transport in graphite is governed by two types of charge carriers, electrons and holes. Their phase and frequency values are in agreement with the predictions of the SWM-model. The SWM-model is confirmed by detailed band structure calculations using the magnetic field Hamiltonian of graphite. The movement of the Fermi at B > 2 T is calculated self-consistently assuming that the sum of the electron and hole concentrations is constant. The second part of the thesis deals with high field magneto-transport of natural graphite in the magnetic field range 0 ≤ B ≤ 28 T. Both spin splitting of magneto-transport features in tilted field configuration and the onset of the charge density wave (CDW) phase for different temperatures with the magnetic field applied normal to the sample plane are discussed. Concerning the Zeeman effect, the SWM calculations including the Fermi energy movement require a g-factor of g* equal to 2.5 ± 0.1 to reproduce the spin spilt features. The measurements of the charge density wave state confirm that its onset magnetic field can be described by a Bardeen-Cooper-Schrieffer (BCS)-type formula. The measurements of the de Haas-van Alphen effect are in agreement with the results of the magneto-transport measurements at low field. (author)

  7. Abrasion behavior of graphite pebble in lifting pipe of pebble-bed HTR

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Ke; Su, Jiageng [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Zhou, Hongbo [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Chinergy Co., LTD., Beijing 100193 (China); Peng, Wei; Liu, Bing [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Yu, Suyun, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, The Key Laboratory for Thermal Science and Power Engineering, Ministry of Educations, Tsinghua University, Beijing 10084 (China)

    2015-11-15

    Highlights: • Quantitative determination of abrasion rate of graphite pebbles in different lifting velocities. • Abrasion behavior of graphite pebble in helium, air and nitrogen. • In helium, intensive collisions caused by oscillatory motion result in more graphite dust production. - Abstract: A pebble-bed high-temperature gas-cooled reactor (pebble-bed HTR) uses a helium coolant, graphite core structure, and spherical fuel elements. The pebble-bed design enables on-line refueling, avoiding refueling shutdowns. During circulation process, the pebbles are lifted pneumatically via a stainless steel lifting pipe and reinserted into the reactor. Inevitably, the movement of the fuel elements as they recirculate in the reactor produces graphite dust. Mechanical wear is the primary source of graphite dust production. Specifically, the sources are mechanisms of pebble–pebble contact, pebble–wall (structural graphite) contact, and fuel handling (pebble–metal abrasion). The key contribution to graphite dust production is from the fuel handling system, particularly from the lifting pipe. During pneumatic lift, graphite pebbles undergo multiple collisions with the stainless steel lifting pipe, thereby causing abrasion of the graphite pebbles and producing graphite dust. The present work explored the abrasion behavior of graphite pebble in the lifting pipe by measuring the abrasion rate at different lifting velocities. The abrasion rate of the graphite pebble in helium was found much higher than those in air and nitrogen. This gas environment effect could be explained by either tribology behavior or dynamic behavior. Friction testing excluded the possibility of tribology reason. The dynamic behavior of the graphite pebble was captured by analysis of the audio waveforms during pneumatic lift. The analysis results revealed unique dynamic behavior of the graphite pebble in helium. Oscillation and consequently intensive collisions occur during pneumatic lift, causing

  8. Thermodynamics of sublimation and solvation for bicyclo-derivatives of 1,3-thiazine

    International Nuclear Information System (INIS)

    Ol’khovich, Marina V.; Blokhina, Svetlana V.; Sharapova, Angelica V.; Perlovich, German L.; Proshin, Alexey N.

    2013-01-01

    Highlights: • Temperature dependencies of saturated vapor pressure of new bicyclo-derivatives were obtained. • Thermodynamic functions of sublimation and solvation were calculated. • The correlations between thermodynamic functions and molecular descriptors are discussed. - Abstract: Temperature dependencies of saturated vapor pressure of novel bicyclo-derivatives of 1,3-thiazine with methoxy- and carbonyl-substituents have been obtained by method of transference by means of an inert gas carrier. Thermodynamic functions of sublimation have been calculated. Correlations between thermodynamic functions of sublimation and thermophysical properties of the substances and molecular descriptors have been established. The enthalpies of solvation of compounds were calculated using the measured values of enthalpies of sublimation and of standard enthalpies of solution in hexane and buffer

  9. Potential Identification of Sublimation-Driven Downslope Mass Movement on Mercury

    Science.gov (United States)

    Malliband, C. C.; Conway, S. J.; Rothery, D. A.; Balme, M. R.

    2018-05-01

    We have identified a further example of mass movement, in addition to the previously identified example in the pyroclastic vent NE of Rachmaninoff. Both examples show evidence of hollow sublimation being a cause of the mass movements.

  10. Schiller Goes to the Movies: Locating the Sublime in "Thelma and Louise."

    Science.gov (United States)

    Hoyng, Peter

    1997-01-01

    Endeavors to make students aware of similarities between today's movie culture and the theater of the 18th century; parallels between a traditional drama and a movie script; and Schiller's understanding of the sublime. (36 references) (Author/CK)

  11. Measured and modelled sublimation on the tropical Glaciar Artesonraju, Perú

    OpenAIRE

    Winkler , M.; Juen , I.; Mölg , T.; Wagnon , Patrick; Gómez , J.; Kaser , G.

    2009-01-01

    Sublimation plays a decisive role in the surface energy and mass balance of tropical glaciers. During the dry season (May–September) low specific humidity and high surface roughness favour the direct transition from ice to vapour and drastically reduce the energy available for melting. However, field measurements are scarce and little is known about the performance of sublimation parameterisations in glacier mass balance and runoff models.

    During 15 days in August 2005 su...

  12. Experimental Analysis of Sublimation Dynamics for Buried Glacier Ice in Beacon Valley, Antarctica

    Science.gov (United States)

    Ehrenfeucht, S.; Dennis, D. P.; Marchant, D. R.

    2017-12-01

    The age of the oldest known buried ice in Beacon Valley, McMurdo Dry Valleys (MDV) Antarctica is a topic of active debate due to its implications for the stability of the East Antarctic Ice Sheet. Published age estimates range from as young as 300 ka to as old as 8.1 Ma. In the upland MDV, ablation occurs predominantly via sublimation. The relict ice in question (ancient ice from Taylor Glacier) lies buried beneath a thin ( 30-70 cm) layer of sublimation till, which forms as a lag deposit as underlying debris-rich ice sublimes. As the ice sublimates, the debris held within the ice accumulates slowly on the surface, creating a porous boundary between the buried-ice surface and the atmosphere, which in turn influences gas exchange between the ice and the atmosphere. Additionally, englacial debris adds several salt species that are ultimately concentrated on the ice surface. It is well documented the rate of ice sublimation varies as a function of overlying till thickness. However, the rate-limiting dynamics under varying environmental conditions, including the threshold thicknesses at which sublimation is strongly retarded, are not yet defined. To better understand the relationships between sublimation rate, till thickness, and long-term surface evolution, we build on previous studies by Lamp and Marchant (2017) and evaluate the role of till thickness as a control on ice loss in an environmental chamber capable of replicating the extreme cold desert conditions observed in the MDV. Previous work has shown that this relationship exhibits exponential decay behavior, with sublimation rate significantly dampened under less than 10 cm of till. In our experiments we pay particular attention to the effect of the first several cm of till in order to quantify the dynamics that govern the transition from bare ice to debris-covered ice. We also examine this transition for various forms of glacier ice, including ice with various salt species.

  13. Design development of graphite primary structures enables SSTO success

    Science.gov (United States)

    Biagiotti, V. A.; Yahiro, J. S.; Suh, Daniel E.; Hodges, Eric R.; Prior, Donald J.

    1997-01-01

    This paper describes the development of a graphite composite wing and a graphite composite intertank primary structure for application toward Single-Stage to Orbit space vehicles such as those under development in NASA's X-33/Reusable Launch Vehicle (RLV) Program. The trade study and designs are based on a Rockwell vertical take-off and horizontal landing (VTHL) wing-body RLV vehicle. Northrop Grumman's approach using a building block development technique is described. Composite Graphite/Bismaleimide (Gr/BMI) material characterization test results are presented. Unique intertank and wing composite subcomponent test article designs are described and test results to date are presented. Wing and intertank Full Scale Section Test Article (FSTA) objectives and designs are outlined. Trade studies, supporting building block testing, and FSTA demonstrations combine to develop graphite primary structure composite technology that enables developing X-33/RLV design programs to meet critical SSTO structural weight and operations performance criteria.

  14. Variation of the properties of siliconized graphite during neutron irradiation

    International Nuclear Information System (INIS)

    Virgil'ev, Y.S.; Chugunova, T.K.; Pikulik, R.G.

    1986-01-01

    The authors evaluate the radiation-induced property changes in siliconized graphite of the industrial grades SG-P and SG-M. The authors simultaneously tested the reference (control) specimens of graphite that are used as the base for obtaining the SG-M siliconized graphite by impregnating with silicon. The suggested scheme (model) atributes the dimensional changes of the siliconized graphite specimens to the effect of the quantitative ratio of the carbide phase and carbon under different conditions of irradiation. If silicon is insufficient for the formation of a dense skeleton, graphite plays a devisive role, and it may be assumed that at an irradiation temperature greater than 600 K, the material shrinks. The presence of isolated carbide inclusions also affects the physicomechanical properties (including the anitfriction properties)

  15. Relationships between fusion, solution, vaporization and sublimation enthalpies of substituted phenols

    International Nuclear Information System (INIS)

    Yagofarov, Mikhail I.; Nagrimanov, Ruslan N.; Solomonov, Boris N.

    2017-01-01

    Highlights: • Method for determination of sublimation and vaporization enthalpies of phenols was developed. • Vaporization enthalpies of 28 phenols at 298 K were calculated. • Sublimation enthalpies of 26 phenols at 298 K were calculated using fusion enthalpies at melting temperatures. • Obtained values are in good agreement with the results of conventional methods. - Abstract: In this work a method for determination of sublimation and vaporization enthalpies of substituted phenols was developed. This method is a modification of solution calorimetry approach. Modification is based on the novel relations, which bind solution, vaporization and sublimation enthalpies at 298.15 K and fusion enthalpy at the melting temperature. According to novel relations the equations for calculating sublimation and vaporization enthalpies at 298.15 K were offered. Calculated values of sublimation and vaporization enthalpies of phenol derivatives containing alkyls, halogens, –OCH 3 , –NO 2 , –COCH 3 , –COOCH 3 groups, and dihydroxybenzenes were compared with literature data (298.15 K) obtained by conventional methods. In most of the cases divergence does not exceed 2–3%.

  16. Transient thermal protection of film covering circular aperture by sublimation and weak decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Havstad, Mark A.; Miles, Robin R.; Hsieh, Henry, E-mail: hsieh6@llnl.gov

    2015-03-15

    Highlights: • Precise sublimating layers can provide protection in transient thermal environments. • Sensitivity analysis shows that the uncertainty in properties has modest influence. • It is likely that methane layers are a good choice for IFE targets. - Abstract: Unwanted heating of sensitive surfaces in harsh thermal environments can be prevented by precise application of sacrificial materials such as sublimation layers and pyrolyzing films. The use of sublimation for the protection of circular polyimide membranes subjected to brief (∼100 ms) heating by infrared radiation and hot (6000 K) inert gas convection is analyzed. Selection of sublimation material and sublimation layer and membrane thickness is considered with emphasis on providing sufficient thermal protection yet negligible unwanted material remaining at the end of a specified heating period. Though the analysis here is general, the motivation is protection of the polyimide films covering the laser entrance holes on IFE (inertial fusion energy) hohlraums being injected into the hot gas (xenon) protecting IFE reactor chambers. Both one and two dimensional thermal models are used to develop a robust thermal concept. Sensitivity analyses (SA) methods are exercised to show where the design may be vulnerable and which input parameters have the greatest effect on performance and likelihood of success. For the design and conditions considered, methane sublimating layers are probably preferred over xenon or pentane.

  17. Effects of graphite on rheological and conventional properties of bituminous binders

    Directory of Open Access Journals (Sweden)

    Yunus Erkuş

    2017-07-01

    Full Text Available In this study, the effects of graphite used for developing the rheological and conventional properties of bitumen were investigated using various bituminous binder tests. Penetration, softening point, rotational viscosity (RV, dynamic shear rheometer (DSR and bending beam rheometer (BBR tests were applied to bituminous binders modified with four different proportions of graphite by bitumen weight. The penetration values declined while softening point values increased with rising graphite content. While graphite induced 8 °C increases in mixing-compacting temperature by increasing the viscosity values, it also increased the rutting parameter. According to the BBR test, the deformation and stiffness values changed significantly with increasing graphite content, but the m-values did not change significantly. These results showed that graphite generally used for improving the thermal properties can improve to high temperature performance of mixtures. Keywords: Graphite, Bitumen, Conventional properties, Rheological properties

  18. DEVELOPMENT OF VACUUM SUBLIMATION DRYERS USING THERMOELECTRIC MODULES

    Directory of Open Access Journals (Sweden)

    R. A. Barykin

    2014-01-01

    Full Text Available Summary. The main directions of use of freeze-dryed products and ingredients are revealed. The analysis of sales markets of freeze-dryed products is provided. It is shown that introduction of innovative production technologies will allow to develop dynamically not only to the large companies, but also small firms that will create prerequisites for growth of the Russian market of freeze-dryed products. Tendencies of development of the freeze-drying equipment are analysed. Relevance of development of energy saving freeze-dryers is proved The integrated approach to creation of competitive domestic technologies and the equipment for sublimation dehydration of thermolabile products consists in use of the effective combined remedies of a power supply, a process intensification, reduction of specific energy consumption and, as a result, decrease in product cost at achievement of high quality indicators. Advantages of thermoelectric modules as alternative direction to existing vapor-compression and absorbing refrigerating appliances are given. Researches of process of freeze-drying dehydration with use of thermoelectric modules are conducted. It is scientifically confirmed, that the thermoelectric module working at Peltier effect, promotes increase in refrigerating capacity due to use of the principle of the thermal pump. Options of use of thermoelectric modules in designs of dryers are offered. Optimum operating modes and number of modules in section are defined. Ways of increase of power efficiency of freeze-dryers with use of thermoelectric modules are specified. The received results will allow to make engineering calculations and design of progressive freeze-drying installations with various ways of a power supply.

  19. Harwell Graphite Calorimeter

    International Nuclear Information System (INIS)

    Linacre, J.K.

    1970-01-01

    The calorimeter is of the steady state temperature difference type. It contains a graphite sample supported axially in a graphite outer jacket, the assembly being contained in a thin stainless steel outer can. The temperature of the jacket and the temperature difference between sample and jacket are measured by chromel-alumel thermocouples. The instrument is calibrated by means of an electric heater of low mass positioned on the axis of the sample. The resistance of the heater is known and both current through the heater and the potential across it may be measured. The instrument is filled with nitrogen at a pressure of one half atmosphere at room temperature. The calorimeter has been designed for prolonged operation at temperatures up to 600°C, and dose rates up to 1 Wg -1 , and instruments have been in use for periods in excess of one year

  20. A standard graphite block

    Energy Technology Data Exchange (ETDEWEB)

    Ivkovic, M; Zdravkovic, Z; Sotic, O [Department of Reactor Physics and Dynamics, Boris Kidric Institute of nuclear sciences Vinca, Belgrade (Yugoslavia)

    1966-04-15

    A graphite block was calibrated for the thermal neutron flux of the Ra-Be source using indium foils as detectors. Experimental values of the thermal neutron flux along the central vertical axis of the system were corrected for the self-shielding effect and depression of flux in the detector. The experimental values obtained were compared with the values calculated on the basis of solving the conservation neutron equation by the continuous slowing-down theory. In this theoretical calculation of the flux the Ra-Be source was divided into three resonance energy regions. The measurement of the thermal neutron diffusion length in the standard graphite block is described. The measurements were performed in the thermal neutron region of the system. The experimental results were interpreted by the diffusion theory for point thermal neutron source in the finite system. The thermal neutron diffusion length was calculated to be L= 50.9 {+-}3.1 cm for the following graphite characteristics: density = 1.7 g/cm{sup 3}; boron content = 0.1 ppm; absorption cross section = 3.7 mb.

  1. A standard graphite block

    International Nuclear Information System (INIS)

    Ivkovic, M.; Zdravkovic, Z.; Sotic, O.

    1966-04-01

    A graphite block was calibrated for the thermal neutron flux of the Ra-Be source using indium foils as detectors. Experimental values of the thermal neutron flux along the central vertical axis of the system were corrected for the self-shielding effect and depression of flux in the detector. The experimental values obtained were compared with the values calculated on the basis of solving the conservation neutron equation by the continuous slowing-down theory. In this theoretical calculation of the flux the Ra-Be source was divided into three resonance energy regions. The measurement of the thermal neutron diffusion length in the standard graphite block is described. The measurements were performed in the thermal neutron region of the system. The experimental results were interpreted by the diffusion theory for point thermal neutron source in the finite system. The thermal neutron diffusion length was calculated to be L= 50.9 ±3.1 cm for the following graphite characteristics: density = 1.7 g/cm 3 ; boron content = 0.1 ppm; absorption cross section = 3.7 mb

  2. Measured and modelled sublimation on the tropical Glaciar Artesonraju, Perú

    Directory of Open Access Journals (Sweden)

    M. Winkler

    2009-02-01

    Full Text Available Sublimation plays a decisive role in the surface energy and mass balance of tropical glaciers. During the dry season (May–September low specific humidity and high surface roughness favour the direct transition from ice to vapour and drastically reduce the energy available for melting. However, field measurements are scarce and little is known about the performance of sublimation parameterisations in glacier mass balance and runoff models.

    During 15 days in August 2005 sublimation was measured on the tongue of Glaciar Artesonraju (8°58' S, 77°38' W in the Cordillera Blanca, Perú, using simple lysimeters. Indicating a strong dependence on surface roughness, daily totals of sublimation range from 1–3 kg m−2 for smooth to 2–5 kg m−2 for rough conditions. (The 15-day means at that time of wind speed and specific humidity were 4.3 m s−1 and 3.8 g kg−1, respectively.

    Measured sublimation was related to characteristic surface roughness lengths for momentum (zm and for the scalar quantities of temperature and water vapour (zs, using a process-based mass balance model. Input data were provided by automatic weather stations, situated on the glacier tongue at 4750 m a.s.l. and 4810 m a.s.l., respectively. Under smooth conditions the combination zm=2.0 mm and zs=1.0 mm appeared to be most appropriate, for rough conditions zm=20.0 mm and zs=10.0 mm fitted best.

    Extending the sublimation record from April 2004 to December 2005 with the process-based model confirms, that sublimation shows a clear seasonality. 60–90% of the energy available for ablation is consumed by sublimation in the dry season, but only 10–15% in the wet season (October–April. The findings are finally used to evaluate the parameterisation of sublimation in the lower-complexity mass

  3. Measured and modelled sublimation on the tropical Glaciar Artesonraju, Perú

    Science.gov (United States)

    Winkler, M.; Juen, I.; Mölg, T.; Wagnon, P.; Gómez, J.; Kaser, G.

    2009-02-01

    Sublimation plays a decisive role in the surface energy and mass balance of tropical glaciers. During the dry season (May-September) low specific humidity and high surface roughness favour the direct transition from ice to vapour and drastically reduce the energy available for melting. However, field measurements are scarce and little is known about the performance of sublimation parameterisations in glacier mass balance and runoff models. During 15 days in August 2005 sublimation was measured on the tongue of Glaciar Artesonraju (8°58' S, 77°38' W) in the Cordillera Blanca, Perú, using simple lysimeters. Indicating a strong dependence on surface roughness, daily totals of sublimation range from 1-3 kg m-2 for smooth to 2-5 kg m-2 for rough conditions. (The 15-day means at that time of wind speed and specific humidity were 4.3 m s-1 and 3.8 g kg-1, respectively.) Measured sublimation was related to characteristic surface roughness lengths for momentum (zm) and for the scalar quantities of temperature and water vapour (zs), using a process-based mass balance model. Input data were provided by automatic weather stations, situated on the glacier tongue at 4750 m a.s.l. and 4810 m a.s.l., respectively. Under smooth conditions the combination zm=2.0 mm and zs=1.0 mm appeared to be most appropriate, for rough conditions zm=20.0 mm and zs=10.0 mm fitted best. Extending the sublimation record from April 2004 to December 2005 with the process-based model confirms, that sublimation shows a clear seasonality. 60-90% of the energy available for ablation is consumed by sublimation in the dry season, but only 10-15% in the wet season (October-April). The findings are finally used to evaluate the parameterisation of sublimation in the lower-complexity mass balance model ITGG, which has the advantage of requiring precipitation and air temperature as only input data. It turns out that the implementation of mean wind speed is a possible improvement for the representation of

  4. Structural disorder of graphite and implications for graphite thermometry

    Science.gov (United States)

    Kirilova, Martina; Toy, Virginia; Rooney, Jeremy S.; Giorgetti, Carolina; Gordon, Keith C.; Collettini, Cristiano; Takeshita, Toru

    2018-02-01

    Graphitization, or the progressive maturation of carbonaceous material, is considered an irreversible process. Thus, the degree of graphite crystallinity, or its structural order, has been calibrated as an indicator of the peak metamorphic temperatures experienced by the host rocks. However, discrepancies between temperatures indicated by graphite crystallinity versus other thermometers have been documented in deformed rocks. To examine the possibility of mechanical modifications of graphite structure and the potential impacts on graphite thermometry, we performed laboratory deformation experiments. We sheared highly crystalline graphite powder at normal stresses of 5 and 25 megapascal (MPa) and aseismic velocities of 1, 10 and 100 µm s-1. The degree of structural order both in the starting and resulting materials was analyzed by Raman microspectroscopy. Our results demonstrate structural disorder of graphite, manifested as changes in the Raman spectra. Microstructural observations show that brittle processes caused the documented mechanical modifications of the aggregate graphite crystallinity. We conclude that the calibrated graphite thermometer is ambiguous in active tectonic settings.

  5. Structural disorder of graphite and implications for graphite thermometry

    Directory of Open Access Journals (Sweden)

    M. Kirilova

    2018-02-01

    Full Text Available Graphitization, or the progressive maturation of carbonaceous material, is considered an irreversible process. Thus, the degree of graphite crystallinity, or its structural order, has been calibrated as an indicator of the peak metamorphic temperatures experienced by the host rocks. However, discrepancies between temperatures indicated by graphite crystallinity versus other thermometers have been documented in deformed rocks. To examine the possibility of mechanical modifications of graphite structure and the potential impacts on graphite thermometry, we performed laboratory deformation experiments. We sheared highly crystalline graphite powder at normal stresses of 5 and 25  megapascal (MPa and aseismic velocities of 1, 10 and 100 µm s−1. The degree of structural order both in the starting and resulting materials was analyzed by Raman microspectroscopy. Our results demonstrate structural disorder of graphite, manifested as changes in the Raman spectra. Microstructural observations show that brittle processes caused the documented mechanical modifications of the aggregate graphite crystallinity. We conclude that the calibrated graphite thermometer is ambiguous in active tectonic settings.

  6. Effect of total pressure on graphite oxidation

    International Nuclear Information System (INIS)

    Burnette, R.D.; Hoot, C.G.

    1983-04-01

    Graphite corrosion in the high-temperature gas-cooled reactor (HTGR) is calculated using two key assumptions: (1) the kinetic, catalysis, and transport characteristics of graphite determined by bench-scale tests apply to large components at reactor conditions and (2) the effects of high pressure and turbulent flow are predictable. To better understand the differences between laboratory tests and reactor conditions, a high-pressure test loop (HPTL) has been constructed and used to perform tests at reactor temperature, pressure, and flow conditions. The HPTL is intended to determine the functional dependence of oxidation rate and characteristics on total pressure and gas velocity and to compare the oxidation results with calculations using models and codes developed for the reactor

  7. Bromine intercalated graphite for lightweight composite conductors

    KAUST Repository

    Amassian, Aram

    2017-07-20

    A method of fabricating a bromine-graphite/metal composite includes intercalating bromine within layers of graphite via liquid-phase bromination to create brominated-graphite and consolidating the brominated-graphite with a metal nanopowder via a mechanical pressing operation to generate a bromine-graphite/metal composite material.

  8. Chemical stabilization of graphite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bistrika, Alexander A.; Lerner, Michael M.

    2018-04-03

    Embodiments of a device, or a component of a device, including a stabilized graphite surface, methods of stabilizing graphite surfaces, and uses for the devices or components are disclosed. The device or component includes a surface comprising graphite, and a plurality of haloaryl ions and/or haloalkyl ions bound to at least a portion of the graphite. The ions may be perhaloaryl ions and/or perhaloalkyl ions. In certain embodiments, the ions are perfluorobenzenesulfonate anions. Embodiments of the device or component including stabilized graphite surfaces may maintain a steady-state oxidation or reduction surface current density after being exposed to continuous oxidation conditions for a period of at least 1-100 hours. The device or component is prepared by exposing a graphite-containing surface to an acidic aqueous solution of the ions under oxidizing conditions. The device or component can be exposed in situ to the solution.

  9. Heat exchanger using graphite foam

    Science.gov (United States)

    Campagna, Michael Joseph; Callas, James John

    2012-09-25

    A heat exchanger is disclosed. The heat exchanger may have an inlet configured to receive a first fluid and an outlet configured to discharge the first fluid. The heat exchanger may further have at least one passageway configured to conduct the first fluid from the inlet to the outlet. The at least one passageway may be composed of a graphite foam and a layer of graphite material on the exterior of the graphite foam. The layer of graphite material may form at least a partial barrier between the first fluid and a second fluid external to the at least one passageway.

  10. Graphite waste incineration in a fluidized bed

    International Nuclear Information System (INIS)

    Guiroy, J.J.

    1996-01-01

    French gas-cooled reactors belonging to the Atomic Energy Commission (CEA), Electricite de France (EDF), Hifrensa (Spain), etc., commissioned between the 1950s and 1970s, have generated large quantities of graphite wastes, mainly in the form of spent fuel sleeves. Furthermore, some of these reactors scheduled for dismantling in the near future (such as the G2 and G3 reactors at Marcoule) have cores consisting of graphite blocks. Consequently, a fraction of the contaminated graphite, amounting to 6000 t in France for example, must be processed in the coming years. For this processing, incineration using a circulating fluidized bed combustor has been selected as a possible solution and validated. However, the first operation to be performed involves recovering this graphite waste, and particularly, first of all, the spent fuel sleeves that were stored in silos during the years of reactor operation. Subsequent to the final shutdown of the Spanish gas-cooled reactor unit, Vandellos 1, the operating utility Hifrensa awarded contracts to a Framatome Iberica SA/ENSA consortium for removing, sorting, and prepackaging of the waste stored in three silos on the Vandellos site, essentially graphite sleeves. On the other hand, a program to validate the Framatome fluidized bed incineration process was carried out using a prototype incinerator installed at Le Creusot, France. The validation program included 22 twelve-hour tests and one 120-hour test. Particular attention was paid to the safety aspects of this project. During the performance of the validation program, a preliminary safety assessment was carried out. An impact assessment was performed with the help of the French Institute for Protection and Nuclear Safety, taking into account the preliminary spectra supplied by the CEA and EDF, and the activities of the radionuclides susceptible of being released into the atmosphere during the incineration. (author). 4 refs, 11 figs, 1 tab

  11. Mechanism and kinetics for ammonium dinitramide (ADN) sublimation: a first-principles study.

    Science.gov (United States)

    Zhu, R S; Chen, Hui-Lung; Lin, M C

    2012-11-08

    The mechanism for sublimation of NH(4)N(NO(2))(2) (ADN) has been investigated quantum-mechanically with generalized gradient approximation plane-wave density functional theory calculations; the solid surface is represented by a slab model and the periodic boundary conditions are applied. The calculated lattice constants for the bulk ADN, which were found to consist of NH(4)(+)[ON(O)NNO(2)](-) units, instead of NH(4)(+)[N(NO(2))(2)](-), agree quite well with experimental values. Results show that three steps are involved in the sublimation/decomposition of ADN. The first step is the relaxation of the surface layer with 1.6 kcal/mol energy per NH(4)ON(O)NNO(2) unit; the second step is the sublimation of the surface layer to form a molecular [NH(3)]-[HON(O)NNO(2)] complex with a 29.4 kcal/mol sublimation energy, consistent with the experimental observation of Korobeinichev et al. (10) The last step is the dissociation of the [H(3)N]-[HON(O)NNO(2)] complex to give NH(3) and HON(O)NNO(2) with the dissociation energy of 13.9 kcal/mol. Direct formation of NO(2) (g) from solid ADN costs a much higher energy, 58.3 kcal/mol. Our calculated total sublimation enthalpy for ADN(s) → NH(3)(g) + HON(O)NNO(2)) (g), 44.9 kcal/mol via three steps, is in good agreement with the value, 42.1 kcal/mol predicted for the one-step sublimation process in this work and the value 44.0 kcal/mol computed by Politzer et al. (11) using experimental thermochemical data. The sublimation rate constant for the rate-controlling step 2 can be represented as k(sub) = 2.18 × 10(12) exp (-30.5 kcal/mol/RT) s(-1), which agrees well with available experimental data within the temperature range studied. The high pressure limit decomposition rate constant for the molecular complex H(3)N···HON(O)NNO(2) can be expressed by k(dec) = 3.18 × 10(13) exp (-15.09 kcal/mol/RT) s(-1). In addition, water molecules were found to increase the sublimation enthalpy of ADN, contrary to that found in the ammonium

  12. Distributed modelling of climate change impacts on snow sublimation in Northern Mongolia

    Directory of Open Access Journals (Sweden)

    L. Menzel

    2009-08-01

    Full Text Available Sublimation of snow is an important factor of the hydrological cycle in Mongolia and is likely to increase according to future climate projections. In this study the hydrological model TRAIN was used to assess spatially distributed current and future sublimation rates based on interpolated daily data of precipitation, air temperature, air humidity, wind speed and solar radiation. An automated procedure for the interpolation of the input data is provided. Depending on the meteorological parameter and the data availability for the individual days, the most appropriate interpolation method is chosen automatically from inverse distance weighting, Ordinary Least Squares interpolation, Ordinary or Universal Kriging. Depending on elevation simulated annual sublimation in the period 1986–2006 was 23 to 35 mm, i.e. approximately 80% of total snowfall. Moreover, future climate projections for 2071–2100 of ECHAM5 and HadCM3, based on the A1B emission scenario of the Intergovernmental Panel on Climate Change, were analysed with TRAIN. In the case of ECHAM5 simulated sublimation increases by up to 17% (26...41 mm while it remains at the same level for HadCM3 (24...34 mm. The differences are mainly due to a distinct increase in winter precipitation for ECHAM5. Simulated changes of the all-season hydrological conditions, e.g. the sublimation-to-precipitation ratio, were ambiguous due to diverse precipitation patterns derived by the global circulation models.

  13. Graphite in Science and Nuclear Technique

    OpenAIRE

    Zhmurikov, E. I.; Bubnenkov, I. A.; Dremov, V. V.; Samarin, S. I.; Pokrovsky, A. S.; Harkov, D. V.

    2013-01-01

    The monograph is devoted to the application of graphite and graphite composites in science and technology. The structure and electrical properties, the technological aspects of production of high-strength synthetic graphites, the dynamics of the graphite destruction, traditionally used in the nuclear industry are discussed. It is focuses on the characteristics of graphitization and properties of graphite composites based on carbon isotope 13C. The book is based, generally, on the original res...

  14. Assessment of management modes for graphite from reactor decommissioning

    International Nuclear Information System (INIS)

    White, I.F.; Smith, G.M.; Saunders, L.J.; Kaye, C.J.; Martin, T.J.; Clarke, G.H.; Wakerley, M.W.

    1984-01-01

    A technological and radiological assessment has been made of the management options for irradiated graphite wastes from the decommissioning of Magnox and advanced gas-cooled reactors. Detailed radionuclide inventories have been estimated, the main contribution being from activation of the graphite and its stable impurities. Three different packaging methods for graphite have been described; each could be used for either sea or land disposal, is logistically feasible and could be achieved at reasonable cost. Leaching tests have been carried out on small samples of irradiated graphite under a variety of conditions including those of the deep ocean bed; the different conditions had little effect on the observed leach rates of radiologically significant radionuclides. Radiological assessments were made of four generic options for disposal of packaged graphite: on the deep ocean bed, in deep geologic repositories at two different types of site, and by shallow land burial. Incineration of graphite was also considered, though this option presents logistical problems. With appropriate precautions during the lifetime of the Cobalt-60 content of the graphite, any of the options considered could give acceptably low doses to individuals, and all would merit further investigation in site-specific contexts

  15. Modification of structural graphite machining

    International Nuclear Information System (INIS)

    Lavrenev, M.M.

    1979-01-01

    Studied are machining procedures for structural graphites (GMZ, MG, MG-1, PPG) most widely used in industry, of the article mass being about 50 kg. Presented are dependences necessary for the calculation of cross sections of chip suction tappers and duster pipelines in machine shops for structural graphite machining

  16. Features of spherical uranium-graphite HTGR fuel elements control

    International Nuclear Information System (INIS)

    Kreindlin, I.I.; Oleynikov, P.P.; Shtan, A.S.

    1985-01-01

    Control features of spherical HTGR uranium-graphite fuel elements with spherical coated fuel particles are mainly determined by their specific construction and fabrication technology. The technology is chiefly based on methods of ceramic fuel (fuel microspheres fabrication) and graphite production practice it is necessary to deal with a lot of problems from determination of raw materials properties to final fuel elements testing. These procedures are described

  17. Features of spherical uranium-graphite HTGR fuel elements control

    Energy Technology Data Exchange (ETDEWEB)

    Kreindlin, I I; Oleynikov, P P; Shtan, A S

    1985-07-01

    Control features of spherical HTGR uranium-graphite fuel elements with spherical coated fuel particles are mainly determined by their specific construction and fabrication technology. The technology is chiefly based on methods of ceramic fuel (fuel microspheres fabrication) and graphite production practice it is necessary to deal with a lot of problems from determination of raw materials properties to final fuel elements testing. These procedures are described.

  18. Glass-Graphite Composite Materials

    International Nuclear Information System (INIS)

    Mayzan, M.Z.H.; Lloyd, J.W.; Heath, P.G.; Stennett, M.C.; Hyatt, N.C.; Hand, R.J.

    2016-01-01

    A summary is presented of investigations into the potential of producing glass-composite materials for the immobilisation of graphite or other carbonaceous materials arising from nuclear power generation. The methods are primarily based on the production of base glasses which are subsequently sintered with powdered graphite or simulant TRISO particles. Consideration is also given to the direct preparation of glass-graphite composite materials using microwave technology. Production of dense composite wasteforms with TRISO particles was more successful than with powdered graphite, as wasteforms containing larger amounts of graphite were resistant to densification and the glasses tried did not penetrate the pores under the pressureless conditions used. Based on the results obtained it is concluded that the production of dense glassgraphite composite wasteforms will require the application of pressure. (author)

  19. Effects of Oxidation on Oxidation-Resistant Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Windes, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Rebecca [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carroll, Mark [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-05-01

    The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.

  20. Blowing snow sublimation and transport over Antarctica from 11 years of CALIPSO observations

    Directory of Open Access Journals (Sweden)

    S. P. Palm

    2017-11-01

    Full Text Available Blowing snow processes commonly occur over the earth's ice sheets when the 10 m wind speed exceeds a threshold value. These processes play a key role in the sublimation and redistribution of snow thereby influencing the surface mass balance. Prior field studies and modeling results have shown the importance of blowing snow sublimation and transport on the surface mass budget and hydrological cycle of high-latitude regions. For the first time, we present continent-wide estimates of blowing snow sublimation and transport over Antarctica for the period 2006–2016 based on direct observation of blowing snow events. We use an improved version of the blowing snow detection algorithm developed for previous work that uses atmospheric backscatter measurements obtained from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite. The blowing snow events identified by CALIPSO and meteorological fields from MERRA-2 are used to compute the blowing snow sublimation and transport rates. Our results show that maximum sublimation occurs along and slightly inland of the coastline. This is contrary to the observed maximum blowing snow frequency which occurs over the interior. The associated temperature and moisture reanalysis fields likely contribute to the spatial distribution of the maximum sublimation values. However, the spatial pattern of the sublimation rate over Antarctica is consistent with modeling studies and precipitation estimates. Overall, our results show that the 2006–2016 Antarctica average integrated blowing snow sublimation is about 393 ± 196 Gt yr−1, which is considerably larger than previous model-derived estimates. We find maximum blowing snow transport amount of 5 Mt km−1 yr−1 over parts of East Antarctica and estimate that the average snow transport from continent to ocean is about 3.7 Gt yr−1. These

  1. Vacuum sublimation of interaction products of neodymium and erbium dipivaloyl methanates with pivalic acid

    International Nuclear Information System (INIS)

    Tu, Z.A.; Kuz'mina, N.P.; Martynenko, L.I.

    1993-01-01

    Processes taking place during vacuum sublimation of solid complexes of individual rare earths prepared in the systems MDpm 3 -nHPiv-hexane (M = Nd, Er, HDpm - dipivaloylmethane, HPiv - pivalic acid, n = 1, 2, 3) were studied. It is pointed out that at n = 1 in the systems considered mixed ligand complexes of the composition ErDpm 3 · HPiv and NdDpm 2 Piv are formed which disproportionate at different temperatures when heated in vacuum. It is revealed that the processes of the complexes disproportionation can be used to increase the efficiency of sublimation methods of neodymium and erbium dipivaloylmethanates mixture separation. 6 refs., 2 figs., 1 tab

  2. Determination of vapor pressures, enthalpies of sublimation, and enthalpies of fusion of benzenetriols

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Schick, Christoph

    2004-01-01

    Molar enthalpies of sublimation of 1,2,4-, 1,2,3-, and 1,3,5-tri-hydroxy-benzene, were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The molar enthalpies of fusion and molar heat capacities of these compounds were measured by DSC. The measured data sets of vaporization, sublimation and fusion enthalpies were checked for internal consistency. Strength of the inter- and intra-molecular hydrogen bonding in di- and tri-hydroxy-benzenes have been assessed

  3. On estimating the fracture probability of nuclear graphite components

    International Nuclear Information System (INIS)

    Srinivasan, Makuteswara

    2008-01-01

    The properties of nuclear grade graphites exhibit anisotropy and could vary considerably within a manufactured block. Graphite strength is affected by the direction of alignment of the constituent coke particles, which is dictated by the forming method, coke particle size, and the size, shape, and orientation distribution of pores in the structure. In this paper, a Weibull failure probability analysis for components is presented using the American Society of Testing Materials strength specification for nuclear grade graphites for core components in advanced high-temperature gas-cooled reactors. The risk of rupture (probability of fracture) and survival probability (reliability) of large graphite blocks are calculated for varying and discrete values of service tensile stresses. The limitations in these calculations are discussed from considerations of actual reactor environmental conditions that could potentially degrade the specification properties because of damage due to complex interactions between irradiation, temperature, stress, and variability in reactor operation

  4. Evaluation of coke microstructure and its effects on graphite fabrication

    International Nuclear Information System (INIS)

    Fotourehchian, S.; Ahmadi, S.

    2001-01-01

    A variety of applications for cokes (metallurgy, petroleum, etc.) have been defined in parallel to the new industrial technology growth. Coke is rich in carbon and has the main role in manufacturing carbonaceous materials such as graphite, steel, silicon carbide, titanium carbide, etc. Among the most important applications of different variety of cokes is their usage for different graphite fabrications. The crystalline structure of graphite (hexagonal with sp 2 hybrid) is based upon the microstructure of coke and it causes anisotropy in properties of produced graphite. Thus, the study of macrostructure and anisotropy degree of cokes is of importance. There are several theoretical and experimental methods to determine the Coke's microstructure and anisotropy. Numerous tests have been conducted on different variety of cokes based on the used method. Here, it is attempted to introduce an applied method to determine the microstructure and anisotropy degree of cokes based upon the kind of application

  5. Thermal strain measurements in graphite using electronic speckle pattern interferometry

    International Nuclear Information System (INIS)

    Tamulevicius, S.; Augulis, L.; Augulis, R.; Zabarskas, V.; Levinskas, R.; Poskas, P.

    2001-01-01

    Two 1500 MW(e) RBMK Units are operated at Ignalina NPP in Lithuania. Due to recent decision of the Parliament on the earlier closure of Unit 1, preparatory work for decommissioning have been initiated. Preferred decommissioning strategy is based on delayed dismantling after rather long safe enclosure period. Since graphite is one of the basic and probably the most voluminous components of the reactor internals, a sufficient information on status and behaviour of graphite moderator and reflector during long time safe enclosure period is of special significance. In this context, thermal strain in graphite is one of the parameters requiring particular interest. Electronic speckle pattern interferometry has been proposed and successfully tested to control this parameter using the real samples of graphite from Ignalina NPP Units. (author)

  6. On the Thermal Conductivity Change of Matrix Graphite Materials after Neutron Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Woo; Yeo, Seunghwan; Kim, Eung-Seon; Sah, Injin; Park, Daegyu; Kim, Youngjun; Cho, Moon Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this work, the variations of the thermal conductivity of the A3-3 matrix graphite after neutron irradiation is discussed as well as of the IG-110 graphite for comparison. Neutron irradiation of the graphite specimens was carried out as a part of the first irradiation test of KAERI's coated particle fuel specimens by use of Hanaro research reactor. This work can be summarized as follows: 1) In the evaluation of the specific heat of the graphite materials, various literature data were used and the variations of the specific heat data of all the graphite specimens are observed well agreed, irrespectively of the difference in specimens (graphite and matrix graphite and irradiated and un-irradiated). 2) This implies that it should be reasonable that for both structural graphite and fuel matrix graphite, and even for the neuron-irradiated graphite, any of these specific heat data set be used in the calculation of the thermal conductivity. 3) For the irradiated A3-3 matrix graphite specimens, the thermal conductivity decreased on both directions. On the radial direction, the tendency of variation upon temperature is similar to that of unirradiated specimen, i.e., decreasing as the temperature increases. 4) In the German irradiation experiments with A3-27 matrix graphite specimens, the thermal conductivity of the un-irradiated specimen shows a decrease and that of irradiated specimen is nearly constant as the temperature increases. 5) The thermal conductivity of the irradiated IG-110 was considerably decreased compared with that of un-irradiated specimens The difference of the thermal conductivity of un-irradiated and irradiated IG-110 graphite specimens is much larger than that of un-irradiated and irradiated A3-3 matrix graphite specimens.

  7. Hypervelocity impacts into graphite

    Science.gov (United States)

    Latunde-Dada, S.; Cheesman, C.; Day, D.; Harrison, W.; Price, S.

    2011-03-01

    Studies have been conducted into the characterisation of the behaviour of commercial graphite (brittle) when subjected to hypervelocity impacts by a range of projectiles. The experiments were conducted with a two-stage gas gun capable of launching projectiles of differing density and strength to speeds of about 6kms-1 at right angles into target plates. The damage caused is quantified by measurements of the crater depth and diameters. From the experimental data collected, scaling laws were derived which correlate the crater dimensions to the velocity and the density of the projectile. It was found that for moderate projectile densities the crater dimensions obey the '2/3 power law' which applies to ductile materials.

  8. Hypervelocity impacts into graphite

    International Nuclear Information System (INIS)

    Latunde-Dada, S; Cheesman, C; Day, D; Harrison, W; Price, S

    2011-01-01

    Studies have been conducted into the characterisation of the behaviour of commercial graphite (brittle) when subjected to hypervelocity impacts by a range of projectiles. The experiments were conducted with a two-stage gas gun capable of launching projectiles of differing density and strength to speeds of about 6kms -1 at right angles into target plates. The damage caused is quantified by measurements of the crater depth and diameters. From the experimental data collected, scaling laws were derived which correlate the crater dimensions to the velocity and the density of the projectile. It was found that for moderate projectile densities the crater dimensions obey the '2/3 power law' which applies to ductile materials.

  9. Acoustic emission from polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, I.; Yoda, S.; Oku, T.; Miyamoto, Y.

    1987-01-01

    Acoustic emission was monitored from polycrystalline graphites with different microstructure (pore size and pore volume) subjected to compressive loading. The graphites used in this study comprised five brands, that is, PGX, ISEM-1, IG-11, IG-15, and ISO-88. A root mean square (RMS) voltage and event counts of acoustic emission for graphites were measured during compressive loading. The acoustic emission was measured using a computed-based data acquisition and analysis system. The graphites were first deformed up to 80 % of the average fracture stress, then unloaded and reloaded again until the fracture occured. During the first loading, the change in RMS voltage for acoustic emission was detected from the initial stage. During the unloading, the RMS voltage became zero level as soon as the applied stress was released and then gradually rose to a peak and declined. The behavior indicated that the reversed plastic deformation occured in graphites. During the second loading, the RMS voltage gently increased until the applied stress exceeded the maximum stress of the first loading; there is no Kaiser effect in the graphites. A bicrystal model could give a reasonable explanation of this results. The empirical equation between the ratio of σ AE to σ f and σ f was obtained. It is considered that the detection of microfracture by the acoustic emission technique is effective in macrofracture prediction of polycrystalline graphites. (author)

  10. Radiolytic graphite oxidation revisited

    International Nuclear Information System (INIS)

    Minshall, P.C.; Sadler, I.A.; Wickham, A.J.

    1996-01-01

    The importance of radiolytic oxidation in graphite-moderated CO 2 -cooled reactors has long been recognised, especially in the Advanced Gas-Cooled Reactors where potential rates are higher because of the higher gas pressure and ratings than the earlier Magnox designs. In all such reactors, the rate of oxidation is partly inhibited by the CO produced in the reaction and, in the AGR, further reduced by the deliberate addition of CH 4 . Significant roles are also played by H 2 and H 2 O. This paper reviews briefly the mechanisms of these processes and the data on which they are based. However, operational experience has demonstrated that these basic principles are unsatisfactory in a number of respects. Gilsocarbon graphites produced by different manufacturers have demonstrated a significant difference in oxidation rate despite a similar specification and apparent equivalence in their pore size and distribution, considered to be the dominant influence on oxidation rate for a given coolant-gas composition. Separately, the inhibiting influence of CH 4 , which for many years had been considered to arise from the formation of a sacrificial deposit on the pore walls, cannot adequately be explained by the actual quantities of such deposits found in monitoring samples which frequently contain far less deposited carbon than do samples from Magnox reactors where the only source of such deposits is the CO. The paper also describes the current status of moderator weight-loss predictions for Magnox and AGR Moderators and the validation of the POGO and DIFFUSE6 codes respectively. 2 refs, 5 figs

  11. Dry Sliding Wear Behavior of Spark Plasma Sintered Fe-Based Bulk Metallic Glass/Graphite Composites

    Directory of Open Access Journals (Sweden)

    Xiulin Ji

    2016-09-01

    Full Text Available Bulk metallic glass (BMG and BMG-graphite composites were fabricated using spark plasma sintering at the sintering temperature of 575 °C and holding time of 15 min. The sintered composites exhibited partial crystallization and the presence of distributed porosity and graphite particles. The effect of graphite reinforcement on the tribological properties of the BMG/graphite composites was investigated using dry ball-on-disc sliding wear tests. The reinforcement of graphite resulted in a reduction in both the wear rate and the coefficient of friction as compared to monolithic BMG samples. The wear surfaces of BMG/graphite composites showed regions of localized wear loss due to microcracking and fracture, as was also the case with the regions covered with graphite-rich protective film due to smearing of pulled off graphite particles.

  12. Imaging of tritium implanted into graphite

    International Nuclear Information System (INIS)

    Malinowski, M.E.; Causey, R.A.

    1988-01-01

    The extensive use of graphite in plasma-facing surfaces of tokamaks such as the Tokamak Fusion Test Reactor, which has planned tritium discharges, makes two-dimensional tritium detection techniques important in helping to determine torus tritium inventories. We have performed experiments in which highly oriented pyrolytic graphite (HOPG) samples were first tritium implanted with fluences of ∼10 16 T/cm 2 at energies approx. 0 C resulted in no discernible motion of tritium along the basal plane, but did show that significant desorption of the implanted tritium occurred. The current results indicate that tritium in quantities of 10 12 T/cm 2 in tritiated components could be readily detected by imaging at lower magnifications

  13. Chemisputtering of interstellar graphite grains

    International Nuclear Information System (INIS)

    Draine, B.T.

    1979-01-01

    The rate of erosion of interstellar graphite grains as a result of chemical reaction with H, N, and O is estimated using the available experiment evidence. It is argued that ''chemical sputtering'' yields for interstellar graphite grains will be much less than unity, contrary to earlier estimates by Barlow and Silk. Chemical sputtering of graphite grains in evolving H II regions is found to be unimportant, except in extremely compact (n/sub H/> or approx. =10 5 cm -3 ) H II regions. Alternative explanations are considered for the apparent weakness of the lambda=2175 A extinction ''bump'' in the direction of several early type stars

  14. Obtention of nuclear grade graphite

    International Nuclear Information System (INIS)

    Ferreira, M.L.

    1984-01-01

    The impurity level of natural graphite found in some of the most important mines of the State of Minas Gerais - Brasil is determined. It is also concerned with the development and use of natural graphite in nuclear reactors. Standard methods for chemical and instrumentsal analysis such as Spectrografic Determination by Emission, Spectrografic Determination by X-Rays, Spectrografic Determination by Atomic Asorption, Photometric Determination, and also chemical and physical methods for separation of impurities as well standard method for Estimating the Thermal Neutron Absorption Cross Section of graphite were employed. Some aditionals methods of purification to the ordinary treatment such as the use of metanol and halogens are also described. (Author) [pt

  15. How to Kill a Journalism School: The Digital Sublime in the Discourse of Discontinuance

    Science.gov (United States)

    McDevitt, Michael; Sindorf, Shannon

    2012-01-01

    The authors argue that journalism's uncertain identity in academia has made it vulnerable to unreflective instrumentalism in the digital era. They show how instrumentalism intertwined with the digital sublime constitutes a rhetorically resonate rationale for closing a journalism school. Evidence comes from documents and testimony associated with…

  16. A re-determination and re-assessment of the thermodynamics of sublimation of uranium dioxide

    International Nuclear Information System (INIS)

    Ackermann, R.J.; Rauh, E.G.; Rand, M.H.

    1980-01-01

    New mass-spectrometric measurements on the ion-intensity of UO 2 + over urania from 1813 to 2463 K are reported. Although the mean value for the enthalpy of sublimation calculated from these measurements is close to previous values, a detailed examination of the results indicates that there is an appreciable curvature in the log p versus reciprocal-temperature curve for the process: UO 2 (s)→UO 2 (g). This is attributed to a large negative ΔCsub(p) for the sublimation reaction, arising from the sharp increase in Csub(p) (UO 2 (s)) above approximately 1750 K. A thorough re-assessment of the previous studies on the sublimation of urania suggests an 'international' average value of psub(UO 2 )=(1.3+-0.1)x10 -6 atm at 2150 K; Knudsen effusion measurements above 2450 K (p>1x10 -4 atm) are thought to be in error due to departures from molecular flow. Thermal functions for UO 2 (g) have been calculated, assuming a linear molecule and electronic contributions to the partition function based on those of ThO(g). Anharmonicity corrections have been included. When these functions are combined with the thermal functions for UO 2 (s), recently assessed, the third law heat of sublimation at 298.15 K becomes 147.8 kcal.mol -1 with a trend of only 0.2 kcal.mol -1 across the temperature range 1800 to 2400 K. (author)

  17. Structure-property relationships in halogenbenzoic acids: Thermodynamics of sublimation, fusion, vaporization and solubility.

    Science.gov (United States)

    Zherikova, Kseniya V; Svetlov, Aleksey A; Kuratieva, Natalia V; Verevkin, Sergey P

    2016-10-01

    Temperature dependences of vapor pressures for 2-, 3-, and 4-bromobenzoic acid, as well as for five isomeric bromo-methylbenzoic acids were studied by the transpiration method. Melting temperatures and enthalpies of fusion for all isomeric bromo-methylbenzoic acids and 4-bromobenzoic acid were measured with a DSC. The molar enthalpies of sublimation and vaporization were derived. These data together with results available in the literature were collected and checked for internal consistency using a group-additivity procedure and results from X-ray structural diffraction studies. Specific (hydrogen bonding) interactions in the liquid and in the crystal phase of halogenbenzoic acids were quantified based on experimental values of vaporization and sublimation enthalpies. Structure-property correlations of solubilities of halogenobenzoic acids with sublimation pressures and sublimation enthalpies were developed and solubilities of bromo-benzoic acids were estimated. These new results resolve much of the ambiguity in the available thermochemical and solubility data on bromobenzoic acids. The approach based on structure property correlations can be applied for the assessment of water solubility of sparingly soluble drugs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Application of ion beam analysis to the selective sublimation processing of thin films for gas sensing

    International Nuclear Information System (INIS)

    Vomiero, A.; Scian, C.; Della Mea, G.; Guidi, V.; Martinelli, G.; Schiffrer, G.; Comini, E.; Ferroni, M.; Sberveglieri, G.

    2006-01-01

    Ion beam analysis was successfully applied to a novel technique, named selective sublimation process (SSP), for deposition of nanostructured gas-sensing films through reactive sputtering. The method consists of the co-deposition of a mixed oxide, one of which has a relatively low sublimation temperature. Annealing at suitable temperature causes the sublimation of the most volatile compound, leaving a layer with adjustable composition. The appropriate choice of thermal treatments and the consequent tailoring of the composition play a crucial role in the determination of the microstructural properties. We developed a model based on diffusion equations that provides a useful guide to control the deposition and processing parameters and we applied the model on the systems TiO 2 -WO 3 and TiO 2 -MoO 3 . Rutherford backscattering (RBS) was demonstrated to be effective for the characterization of the diffusion and sublimation processes during SSP. Experimental results fully agree with theoretical prediction, and allowed the calculation of all the parameters involved in SSP

  19. Graphite oxidation in HTGR atmosphere

    International Nuclear Information System (INIS)

    Growcock, F.B.; Barry, J.J.; Finfrock, C.C.; Rivera, E.; Heiser, J.H. III

    1982-01-01

    On-going and recently completed studies of the effect of thermal oxidation on the structural integrity of HTGR candidate graphites are described, and some results are presented and discussed. This work includes the study of graphite properties which may play decisive roles in the graphites' resistance to oxidation and fracture: pore size distribution, specific surface area and impurity distribution. Studies of strength loss mechanisms in addition to normal oxidation are described. Emphasis is placed on investigations of the gas permeability of HTGR graphites and the surface burnoff phenomenon observed during recent density profile measurements. The recently completed studies of catalytic pitting and the effects of prestress and stress on reactivity and ultimate strength are also discussed

  20. Graphite materials for nuclear reactors

    International Nuclear Information System (INIS)

    Oku, Tatsuo

    1991-01-01

    Graphite materials have been used in the nuclear fission reactors from the beginning of the reactor development for the speed reduction and reflection of neutron. Graphite materials are used both as a moderator and as a reflector in the core of high temperature gas-cooled reactors, and both as a radiation shielding material and as a reflector in the surrounding of the core for the fast breeder reactor. On the other hand, graphite materials are being positively used as a first wall of plasma as it is known that low Z materials are useful for holding high temperature plasma in the nuclear fusion devices. In this paper the present status of the application of graphite materials to the nuclear fission reactors and fusion devices (reactors) is presented. In addition, a part of results on the related properties to the structural design and safety evaluation and results examined on the subjects that should be done in the future are also described. (author)

  1. Glacier mass balance reconstruction by sublimation induced enrichment of chemical species on Cerro Tapado (Chilean Andes

    Directory of Open Access Journals (Sweden)

    P. Ginot

    2006-01-01

    Full Text Available A 36 m long ice core down to bedrock from the Cerro Tapado glacier (5536 m a.s.l, 30°08' S, 69°55' W was analyzed to reconstruct past climatic conditions for Northern Chile. Because of the marked seasonality in the precipitation (short wet winter and extended dry summer periods in this region, major snow ablation and related post-depositional processes occur on the glacier surface during summer periods. They include predominantly sublimation and dry deposition. Assuming that, like measured during the field campaign, the enrichment of chloride was always related to sublimation, the chemical record along the ice core may be applied to reconstruct the history of such secondary processes linked to the past climatic conditions over northern Chile. For the time period 1962–1999, a mean annual net accumulation of 316 mm water equivalent (weq and 327 mm weq loss by sublimation was deduced by this method. This corresponds to an initial total annual accumulation of 539 mm weq. The annual variability of the accumulation and sublimation is related with the Southern Oscillation Index (SOI: higher net-accumulation during El-Niño years and more sublimation during La Niña years. The deepest part of the ice record shows a time discontinuity; with an ice body deposited under different climatic conditions: 290 mm higher precipitation but with reduced seasonal distribution (+470 mm in winter and –180 mm in summer and –3°C lower mean annual temperature. Unfortunately, its age is unknown. The comparison with regional proxy data however let us conclude that the glacier buildup did most likely occur after the dry mid-Holocene.

  2. Thermogravimetric and Differential Scanning Calorimetric Behavior of Ball-Milled Nuclear Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eung Seon; Kim, Min Hwan; Kim, Yong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Yi Hyun; Cho, Seung Yon [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    An examination was made to characterize the oxidation behavior of ball-milled nuclear graphite powder through a TG-DSC analysis. With the ball milling time, the BET surface area increased with the reduction of particle size, but decreased with the chemisorptions of O{sub 2} on the activated surface. The enhancement of the oxidation after the ball milling is attributed to both increases in the specific surface area and atomic scale defects in the graphite structure. In a high temperature gas-cooled reactor, nuclear graphite has been widely used as fuel elements, moderator or reflector blocks, and core support structures owing to its excellent moderating power, mechanical properties and machinability. For the same reason, it will be used in a helium cooled ceramic reflector test blanket module for the ITER. Each submodule has a seven-layer breeding zone, including three neutron multiplier layers packed with beryllium pebbles, three lithium ceramic pebbles packed tritium breeder layers, and a reflector layer packed with 1 mm diameter graphite pebbles to reduce the volume of beryllium. The abrasion of graphite structures owing to relative motion or thermal cycle during operation may produce graphite dust. It is expected that graphite dust will be more oxidative than bulk graphite, and thus the oxidation behavior of graphite dust must be examined to analyze the safety of the reactors during an air ingress accident. In this study, the thermal stability of ball-milled graphite powder was investigated using a simultaneous thermogravimeter-differential scanning calorimeter.

  3. Graphite tail powder and liquid biofertilizer as trace elements source for ground nut

    Science.gov (United States)

    Hindersah, Reginawanti; Setiawati, M. Rochimi; Fitriatin, B. Natalie; Suryatama, Pujawati; Asmiran, Priyanka; Panatarani, Camellia; Joni, I. Made

    2018-02-01

    Utilization of graphite tail waste from the mineral beneficiation processing is very important since it contain significant amount of essential minerals which are necessary for plant growth. These mineral are required in biochemical processes and mainly play an important role as cofactor in enzymatic reaction. The objective of this research is to investigate the performance of graphite tail on supporting plant growth and yield of ground nut (Arachishypogeae L.). A field experiment has been performed to test the performance of mixed graphite tail and reduced organic matter dose. The graphite tail size were reduced to various sieved size, -80 mesh, -100 mesh and -200 mesh. The experiment was setup in randomized block design with 4 treatments and 6 replications for each treatment, while the control plot is received without graphite tail. The results demonstrated that reduced organic matter along with -200 mesh tail has potentially decreased plant height at the end of vegetative growth stage, in contrast for to -80 mesh tail amendment increased individual fresh plant biomass. Statistically, there was no change of plant nodule, individual shoot fresh and dry weight, root nodule, number of pod following any mesh of graphite tail amendment. Reducing organic matter while adding graphite tail of 5% did not change bean weight in all plot. In contrast, reduced organic matter along with 80-mesh graphite tail amendment improved the nut yield per plot. This experiment suggests that graphite tail, mainly -80 mesh graphite tail can be possibly used in legume production.

  4. Strength degradation of oxidized graphite support column in VHTR

    International Nuclear Information System (INIS)

    Park, Byung Ha; No, Hee Cheon

    2010-01-01

    Air-ingress events caused by large pipe breaks are important accidents considered in the design of Very High Temperature Gas-Cooled Reactors (VHTRs). A main safety concern for this type of event is the possibility of core collapse following the failure of the graphite support column, which can be oxidized by ingressed air. In this study, the main target is to predict the strength of the oxidized graphite support column. Through compression tests for fresh and oxidized graphite columns, the compressive strength of IG-110 was obtained. The buckling strength of the IG-110 column is expressed using the following empirical straight-line formula: σ cr,buckling =91.34-1.01(L/r). Graphite oxidation in Zone 1 is volume reaction and that in Zone 3 is surface reaction. We notice that the ultimate strength of the graphite column oxidized in Zones 1 and 3 only depends on the slenderness ratio and bulk density. Its strength degradation oxidized in Zone 1 is expressed in the following nondimensional form: σ/σ 0 =exp(-kd), k=0.114. We found that the strength degradation of a graphite column, oxidized in Zone 3, follows the above buckling empirical formula as the slenderness of the column changes. (author)

  5. Statistical considerations of graphite strength for assessing design allowable stresses

    International Nuclear Information System (INIS)

    Ishihara, M.; Mogi, H.; Ioka, I.; Arai, T.; Oku, T.

    1987-01-01

    Several aspects of statistics need to be considered to determine design allowable stresses for graphite structures. These include: 1) Statistical variation of graphite material strength. 2) Uncertainty of calculated stress. 3) Reliability (survival probability) required from operational and safety performance of graphite structures. This paper deals with some statistical considerations of structural graphite for assessing design allowable stress. Firstly, probability distribution functions of tensile and compressive strengths are investigated on experimental Very High Temperature candidated graphites. Normal, logarithmic normal and Weibull distribution functions are compared in terms of coefficient of correlation to measured strength data. This leads to the adaptation of normal distribution function. Then, the relation between factor of safety and fracture probability is discussed on the following items: 1) As the graphite strength is more variable than metalic material's strength, the effect of strength variation to the fracture probability is evaluated. 2) Fracture probability depending on survival probability of 99 ∼ 99.9 (%) with confidence level of 90 ∼ 95 (%) is discussed. 3) As the material properties used in the design analysis are usually the mean values of their variation, the additional effect of these variations on the fracture probability is discussed. Finally, the way to assure the minimum ultimate strength with required survival probability with confidence level is discussed in view of statistical treatment of the strength data from varying sample numbers in a material acceptance test. (author)

  6. Graphite selection for the PBMR reflector

    International Nuclear Information System (INIS)

    Marsden, B.J.; Preston, S.D.

    2000-01-01

    A high temperature, direct cycle gas turbine, graphite moderated, helium cooled, pebble-bed reactor (PBMR) is being designed and constructed in South Africa. One of the major components in the PBMR is the graphite reflector, which must be designed to last thirty-five full power years. Fast neutron irradiation changes the dimensions and material properties of reactor graphite, thus for design purposes a suitable graphite database is required. Data on the effect of irradiation on nuclear graphites has been gathered for many years, at considerable financial cost, but unfortunately these graphites are no longer available due to rationalization of the graphite industry and loss of key graphite coke supplies. However, it is possible, using un-irradiated graphite materials properties and knowledge of the particular graphite microstructure, to determine the probable irradiation behaviour. Three types of nuclear graphites are currently being considered for the PBMR reflector: an isostatically moulded, fine grained, high strength graphite and two extruded medium grained graphites of moderately high strength. Although there is some irradiation data available for these graphites, the data does not cover the temperature and dose range required for the PBMR. The available graphites have been examined to determine their microstructure and some of the key material properties are presented. (authors)

  7. Development of design data for graphite reinforced epoxy and polyimide composites

    Science.gov (United States)

    Scheck, W. G.

    1974-01-01

    Processing techniques and design data were characterized for a graphite/epoxy composite system that is useful from 75 K to 450 K, and a graphite/polyimide composite system that is useful from 75 K to 589 K. The Monsanto 710 polyimide resin was selected as the resin to be characterized and used with the graphite fiber reinforcement. Material was purchased using the prepreg specification for the design data generation for both the HT-S/710 and HM-S/710 graphite/polyimide composite system. Lamina and laminate properties were determined at 75 K, 297 K, and 589 K. The test results obtained on the skin-stringer components proved that graphite/polyimide composites can be reliably designed and analyzed much like graphite/epoxy composites. The design data generated in the program includes the standard static mechanical properties, biaxial strain data, creep, fatigue, aging, and thick laminate data.

  8. Delamination in surface plies of graphite/epoxy caused by the edge trimming process

    Science.gov (United States)

    Colligan, K.; Ramulu, M.

    Delamination in surface plies of graphite/epoxy laminates caused by edge trimming using polycrystalline diamond (PCD) and carbide cutters is investigated. The effect of several machining variables on formation of delaminations in the surface plies of a graphite fiber reinforced composite material is presented. Machining tests were performed to assess the impact of cutter geometry, feedrate, rotation direction, and graphite fiber orientation. Three typical delamination modes were observed and documented. Feedrate was found to have a significant effect on surface ply delamination in graphite/epoxy composite materials.

  9. R and D and maintenance on graphite tile of divertor region at EAST

    International Nuclear Information System (INIS)

    Ji, X.; Song, Y.T.; Wu, S.T.; Hao, J.; Du, S.; Peng, Y.; Cao, L.; Wang, S.

    2012-01-01

    Highlights: ► Find out the reason of damage of graphite tile. ► Simulation the halo current. ► Stress analysis of graphite tile by ANSYS. ► Do the experiments to test the strength of graphite tile. ► Do the optimization and maintenance of graphite tile. - Abstract: EAST, with full superconducting magnetic coils, had been designed and constructed to address the scientific and engineering issues under steady state operation. The in-vessel components are full graphite tiles as first wall had been operated successfully. In the experiment campaign of 2010, the H mode operation and 1 MA operation have been gotten on EAST. However, in some case, some of the graphite tiles of divertor region are damaged with the plasma parameter enhanced. As most of the damaged graphite tiles are in the divertor region, they are probably damaged by the electro-magnetic force of the halo current when the VDEs occur. The force of the halo current is re-estimated. The structure analysis has been done by the ANSYS software. From the analysis result. It can be obtained that the stress is larger than the allowable stress when the halo current on the graphite tile is larger than 2.7 kA. The tensile testing of the graphite also has been done. As the result, the graphite tiles are damaged when the forces are up to 2400 N. To deal with the problem, two proposes are accepted. In the one hand, the new type graphite material is used, whose tensile strength is up to 45 MPa. In the other hand, the structure of the graphite tiles is optimized.

  10. Snowmelt and sublimation: field experiments and modelling in the High Atlas Mountains of Morocco

    Directory of Open Access Journals (Sweden)

    O. Schulz

    2004-01-01

    Full Text Available Snow in the High Atlas Mountains is a major source for freshwater renewal and for water availability in the semi-arid lowlands of south-eastern Morocco. Snowfall- and snow-ablation monitoring and modelling is important for estimating potential water delivery from the mountain water towers to the forelands. This study is part of GLOWA-IMPETUS, an integrated management project dealing with scarce water resources in West Africa. The Ameskar study area is located to the south of the High Atlas Mountains, in their rain shadow. As a part of the M’Goun river basin within the upper Drâa valley, the study area is characterised by high radiation inputs, low atmospheric humidity and long periods with sub-zero temperatures. Its altitude ranges between 2000 m and 4000 m, with dominant north- and south-facing slopes. Snowfall occurs mainly from November to April but even summit regions can become repeatedly devoid of snow cover. Snow cover maps for the M’Goun basin (1240 km2 are derived from calculations of NDSI (Normalized Difference Snow Index from MODIS satellite images and snow depth is monitored at four automatic weather stations between 2000–4000 m. Snowfall events are infrequent at lower altitudes. The presence of snow penitentes at altitudes above 3000 m indicates that snow sublimation is an important component of snow ablation. Snow ablation was modelled with the UEB Utah Energy Balance Model (Tarboton and Luce, 1996. This single layer, physically-based, point energy and mass balance model is driven by meteorological variables recorded at the automatic weather stations at Tounza (2960 m and Tichki (3260 m. Data from snow pillows at Tounza and Tichki are used to validate the model’s physical performance in terms of energy and water balances for a sequence of two snowfall events in the winter of 2003/4. First UEB modelling results show good overall performance and timing of snowmelt and sublimation compared to field investigations. Up to 44

  11. "Back-fire to lust": G. Stanley Hall, sex-segregated schooling, and the engine of sublimation.

    Science.gov (United States)

    Graebner, William

    2006-08-01

    G. Stanley Hall was an advocate of sex-segregated schooling long after most Americans had accepted coeducation. His position was based in part on personal experience: observations of his father and mother, a repressed and guilt-ridden boyhood sexuality, and his conviction that his own career success was a product of sublimated sexual desire, of erotic energy converted into mental energy. Hall theorized that coeducation put sublimation at risk, and that sex-segregated schools, by contributing to proper gendered development and by prolonging and sublimating the sexual tensions of adolescence, would produce social progress.

  12. High temperature soldering of graphite

    International Nuclear Information System (INIS)

    Anikin, L.T.; Kravetskij, G.A.; Dergunova, V.S.

    1977-01-01

    The effect is studied of the brazing temperature on the strength of the brazed joint of graphite materials. In one case, iron and nickel are used as solder, and in another, molybdenum. The contact heating of the iron and nickel with the graphite has been studied in the temperature range of 1400-2400 ged C, and molybdenum, 2200-2600 deg C. The quality of the joints has been judged by the tensile strength at temperatures of 2500-2800 deg C and by the microstructure. An investigation into the kinetics of carbon dissolution in molten iron has shown that the failure of the graphite in contact with the iron melt is due to the incorporation of iron atoms in the interbase planes. The strength of a joint formed with the participation of the vapour-gas phase is 2.5 times higher than that of a joint obtained by graphite recrystallization through the carbon-containing metal melt. The critical temperatures are determined of graphite brazing with nickel, iron, and molybdenum interlayers, which sharply increase the strength of the brazed joint as a result of the formation of a vapour-gas phase and deposition of fine-crystal carbon

  13. Porous (Swiss-Cheese Graphite

    Directory of Open Access Journals (Sweden)

    Joseph P. Abrahamson

    2018-05-01

    Full Text Available Porous graphite was prepared without the use of template by rapidly heating the carbonization products from mixtures of anthracene, fluorene, and pyrene with a CO2 laser. Rapid CO2 laser heating at a rate of 1.8 × 106 °C/s vaporizes out the fluorene-pyrene derived pitch while annealing the anthracene coke. The resulting structure is that of graphite with 100 nm spherical pores. The graphitizablity of the porous material is the same as pure anthracene coke. Transmission electron microscopy revealed that the interfaces between graphitic layers and the pore walls are unimpeded. Traditional furnace annealing does not result in the porous structure as the heating rates are too slow to vaporize out the pitch, thereby illustrating the advantage of fast thermal processing. The resultant porous graphite was prelithiated and used as an anode in lithium ion capacitors. The porous graphite when lithiated had a specific capacity of 200 mAh/g at 100 mA/g. The assembled lithium ion capacitor demonstrated an energy density as high as 75 Wh/kg when cycled between 2.2 V and 4.2 V.

  14. Elaboration of aluminum oxide-based graphite containing castables

    Science.gov (United States)

    Zhou, Ningsheng

    The aim of this work was set to develop effective and practicable new methods to incorporate natural flake graphite (FG) into the Al2O 3 based castables for iron and steel making applications. Three approaches, viz. micro-pelletized graphite (PG), crushed briquette of Al2O3-graphite (BAG) and TiO2 coated graphite (CFG), have been developed to insert flake graphite into Al2O 3 rich Al2O3-SiC based and Al2O 3-MgO based castables. These approaches were put into effect as countermeasures against the problems caused by FG in order: (1) to agglomerate the FG powders so as to decrease the specific surface area; (2) to diminish the density difference by using crushed carbon bonded compact of oxide-FG mixture; (3) to modify the surface of the flake graphite by forming hydrophilic coating; (4) to control the dispersion state of the graphite in the castable to maintain enough bonding strength; and (5) to use appropriate antioxidants to inhibit the oxidation of FG. The whole work was divided into two stages. In stage one, Al2O 3-SiC-C castables were dealt with to compare 4 modes of inserting graphite, i.e., by PG, BAG, CFG and FG. Overall properties were measured, all in correlation with graphite amount and incorporating mode. In stage two, efforts were made to reduce water demand in the Al2O3-MgO castables system. For this purpose, the matrix portion of the castable mixes was extracted and a coaxial double cylinder viscometer was adopted to investigate rheological characteristics of the matrix slurries vs. 4 kinds of deflocculants, through which the best deflocculant and its appropriate amount were found. Efforts were then made to add up to 30% MgO into the castables, using a limited amount of powders (antioxidants, Si, SiC, B4C and ZrB2, were added respectively or in combination. Overall properties of the castables, were investigated in correlation with MgO amount and graphite and antioxidant packages. Optimization work on oxidation and slag resistance was pursued. Finally

  15. Orbital Evolution of Dust Particles in the Sublimation Zone near the Sun

    Science.gov (United States)

    Shestakova, L. I.; Demchenko, B. I.

    2018-03-01

    We have performed the calculations of the orbital evolution of dust particles from volcanic glass ( p-obsidian), basalt, astrosilicate, olivine, and pyroxene in the sublimation zone near the Sun. The sublimation (evaporation) rate is determined by the temperature of dust particles depending on their radius, material, and distance to the Sun. All practically important parameters that characterize the interaction of spherical dust particles with the radiation are calculated using the Mie theory. The influence of radiation and solar wind pressure, as well as the Poynting-Robertson drag force effects on the dust dynamics, are also taken into account. According to the observations (Shestakova and Demchenko, 2016), the boundary of the dust-free zone is 7.0-7.6 solar radii for standard particles of the zodiacal cloud and 9.1-9.2 solar radii for cometary particles. The closest agreement is obtained for basalt particles and certain kinds of olivine, pyroxene, and volcanic glass.

  16. Concurrent freezing and sublimation of a liquid-saturated porous slab

    International Nuclear Information System (INIS)

    Vaidyanathan, N.; Shamsundar, N.

    1991-01-01

    In this paper analytical models are formulated for describing heat and mass transport during concurrent freezing and sublimation of a one-dimensional liquid-saturated porous slab. The models are based on transient heat transfer in the frozen and wet regions, and quasi-steady heat and mass transfer in the dried region. The enthalpy method in conjunction with a fully implicit finite-difference scheme is employed to obtain the solution in the frozen and wet regions. A quasi-steady solution is used in the dried region. The governing equations are nondimensionalized and parametric studies are performed. The results indicate that the Luikov number, the ambient vapor pressure, and the heat transfer Biot number are important parameters. The results also confirm that the sublimation interface temperature may show significant variations, in contrast to earlier studies in which it was assumed constant

  17. Poetiche del sublime. Il Coro di morti dalle Operette morali a Goffredo Petrassi

    Directory of Open Access Journals (Sweden)

    Giovanni Vito Distefano

    2018-01-01

    Full Text Available In un autore come Leopardi, incline al serio in misura apparentemente esclusiva e poco votato all’arte drammatica, è tuttavia in un piccolo capolavoro tragicomico che possono individuarsi le prime tracce di una moderna estetica del sublime. L’articolo propone innanzitutto una lettura in chiave metapoetica del Coro di morti, volta ad osservare la salda convergenza che nella scrittura leopardiana lega reciporcamente gli avanzamenti del pensiero – la verità di una condizione umana irresolubilmente e incomprensibilmente priva della felicità – e gli sviluppi attinenti al piano formale e a quello della riflessione filosofico-estetica – con la messa in discussione tanto della classicistica estetica della mimesis, quanto di quella romantica del sentimentale. Infine, nella seconda parte, il paradigma estetico del sublime fornirà i termini entro i quali tracciare una ricostruzione del procedimento adattivo che lega all’originale leopardiano la trasposizione musicale realizzata nel 1941 da Goffredo Petrassi.

  18. Standard molar enthalpies of formation and of sublimation of the terphenyl isomers

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.; Lima, Luis M. Spencer S.

    2008-01-01

    The standard (p 0 = 0.1 MPa) molar enthalpies of formation in the crystalline phases of ortho, meta and para-terphenyl isomers, at T = 298.15 K, were derived from the standard molar energies of combustion, measured by mini-bomb combustion calorimetry. The Knudsen mass-loss effusion technique was used to measure the dependence of the vapour pressure of the crystals with the temperature, thus deriving their standard molar enthalpies of sublimation by means of the Clausius-Clapeyron equation. Combining the standard molar enthalpies of formation and sublimation of the crystalline terphenyls, the standard molar enthalpies of formation in the gaseous state, at T = 298.15 K, were derived for the three isomers. Results are provided in a table. The results show small but detectable isomerization enthalpies between the terphenyls, indicating the following relative enthalpic stabilities: m- > p- ∼ o-terphenyl

  19. Thermodynamic study of sublimation, melting and vaporization of scandium(III) dipivaloylmethanate derivatives

    International Nuclear Information System (INIS)

    Zherikova, Kseniya V.; Zelenina, Ludmila N.; Chusova, Tamara P.; Gelfond, Nikolay V.; Morozova, Natalia B.

    2016-01-01

    Highlights: • Thermal properties of two volatile fluorinated Sc(III) beta-diketonates were studied. • Saturated and unsaturated vapor pressures were measured. • DSC analysis was carried out. • Sublimation, evaporation and melting enthalpies and entropies were derived. • Effect of fluorine introduction on volatility and thermal stability was established. - Abstract: The present work deals with the investigation of thermal properties of two volatile scandium(III) beta-diketonates with 2,2,6,6-tetramethyl-4-fluoro-3,5-heptanedione and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione which have been synthesized and purified. Using the static method with glass membrane gauge-manometer the temperature dependencies of saturated and unsaturated vapor pressure were measured for the first time. The temperatures and enthalpies of melting were measured for these compounds by differential scanning calorimetry. The standard thermodynamic characteristics of enthalpy and entropy for sublimation, vaporization and melting processes were derived.

  20. Titanium sublimation pumping systems and performances on the Tandem Mirror Experiment-Upgrade (TMX-U)

    International Nuclear Information System (INIS)

    Pico, R.E.

    1986-01-01

    This paper presents a brief history of the TMX-U Titanium Sublimation Pumping process (gettering). Titanium sublimation pumps offer an economical means of pumping chemically active gases (especially hydrogen) at high speeds, and serves as additional pumps, along with liquid nitrogen-cooled panels, to provide pumping during each physics experiment. Because of the size of the system, a complex computer program was written which is run-time compiled, and then run by the computer. With the multi-tasking capability of the computer, five programs are used in operation and run simultaneously. All getter wire history, deposition, and system notes are stored on the external disc drive. The progress and performance in the four years the system has been used, two year manually controlled, and two computer controlled with be covered. Emphasis on the computer control system and its by-products, which enhance the operation of the TMX-U, will be the subject of this paper

  1. Practical sublimation source for large-scale chromium gettering in fusion devices

    International Nuclear Information System (INIS)

    Simpkins, J.E.; Emerson, L.C.; Mioduszewski, P.K.

    1983-01-01

    This paper describes the technique of chromium gettering with a large-scale sublimation source which resembles in its design the VARIAN Ti-Ball. It consists of a hollow chromium sphere with a diameter of approximately 3 cm and an incandescent filament for radiation heating from inside the ball. While the fabrication of the source is described in a companion paper, we discuss here the gettering technique. The experimental arrangement consists of an UHV system instrumented for total- and partial-pressure measurements, a film-thickness monitor, thermocouples, an optical pyrometer, and appropriate instrumentation to measure the heating power. The results show the temperature and corresponding sublimation rate of the Cr-Ball as function of input power. In addition, an example of the total pumping speed of a gettered surface is shown

  2. Fatigue properties of ductile cast iron containing chunky graphite

    Energy Technology Data Exchange (ETDEWEB)

    Ferro, P., E-mail: ferro@gest.unipd.it [Department of Management and Engineering, University of Padova, Stradella S. Nicola 3, I-36100 Vicenza (Italy); Lazzarin, P.; Berto, F. [Department of Management and Engineering, University of Padova, Stradella S. Nicola 3, I-36100 Vicenza (Italy)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer Experimental determination of high cycle fatigue properties of EN-GJS-400. Black-Right-Pointing-Pointer Evaluation of the influence of chunky graphite morphology on fatigue life. Black-Right-Pointing-Pointer Metallurgical analysis and microstructural parameters determination. Black-Right-Pointing-Pointer Nodule counting and nodularity rating. - Abstract: This work deals with experimental determination of high cycle fatigue properties of EN-GJS-400 ductile cast iron containing chunky graphite. Constant amplitude axial tests were performed at room temperature under a nominal load ratio R = 0. In order to evaluate the influence of chunky graphite morphology on fatigue life, fatigue tests were carried out also on a second set of specimens without this microstructural defect. All samples were taken from the core of a large casting component. Metallurgical analyses were performed on all the samples and some important microstructural parameters (nodule count and nodularity rating, among others) were measured and compared. It was found that a mean content of 40% of chunky graphite in the microstructure (with respect to total graphite content) does not influence significantly the fatigue strength properties of the analysed cast iron. Such result was attributed to the presence of microporosity detected on the surface fracture of the specimens by means of electron scanning microscope.

  3. Fatigue properties of ductile cast iron containing chunky graphite

    International Nuclear Information System (INIS)

    Ferro, P.; Lazzarin, P.; Berto, F.

    2012-01-01

    Highlights: ► Experimental determination of high cycle fatigue properties of EN-GJS-400. ► Evaluation of the influence of chunky graphite morphology on fatigue life. ► Metallurgical analysis and microstructural parameters determination. ► Nodule counting and nodularity rating. - Abstract: This work deals with experimental determination of high cycle fatigue properties of EN-GJS-400 ductile cast iron containing chunky graphite. Constant amplitude axial tests were performed at room temperature under a nominal load ratio R = 0. In order to evaluate the influence of chunky graphite morphology on fatigue life, fatigue tests were carried out also on a second set of specimens without this microstructural defect. All samples were taken from the core of a large casting component. Metallurgical analyses were performed on all the samples and some important microstructural parameters (nodule count and nodularity rating, among others) were measured and compared. It was found that a mean content of 40% of chunky graphite in the microstructure (with respect to total graphite content) does not influence significantly the fatigue strength properties of the analysed cast iron. Such result was attributed to the presence of microporosity detected on the surface fracture of the specimens by means of electron scanning microscope.

  4. A reliability based stress-life evaluation of aluminium-graphite particulate composites

    International Nuclear Information System (INIS)

    Achutha, M.V.; Sridhara, B.K.; Abdul Budan, D.

    2008-01-01

    Fatigue tests were conducted on sand cast aluminium-graphite composite specimens on Rotating Beam Fatigue Testing Machine with three different stress levels. Aluminium-graphite (LM 25-5% graphite) composite was processed by closed mould sand casting method. Three-stress level fatigue test program was planned for carrying out fatigue experiments. Three different stress levels selected for fatigue experiments were a fraction of ultimate tensile strength. Statistical design of fatigue experiments was carried out to determine the sample size at each stress level. Experimental results are presented in the form of stress-life (S-N) curves and reliability-stress-life (R-S-N) curves, which are helpful for designers. The S-N curve of the aluminium-graphite composite was compared with its matrix alloy LM 25. Comparison revealed that the fatigue behaviour of the aluminium-graphite composite is superior to that of the matrix alloy

  5. Thermal fatigue of refractory metal / graphite composites for fusion applications

    International Nuclear Information System (INIS)

    Smid, I.; Nickel, H.

    1989-01-01

    Reactor grade graphite and molybdenum (TZM) were brazed with different high temperature brazes. The resulting composite tiles had a size of 50 mm x 50 mm with a graphite thickness of 10 mm and a TZM thickness of 5mm. The brazed composites have been tested in electron beam simulation for their thermal fatigue properties. The parameters of these tests were chosen to match NET design specifications for normal operation and 'slow' peak energy deposition. The resulting damages and microstructural changes on the graphites and the brazes are discussed. Additional information is supplied on X-ray diffraction data proving the presence of different phases in the brazes. Finally the influence of a hydrogen plasma on the adaptability of the investigated brazes in fusion devices is discussed. 12 refs., 4 tabs., 4 figs. (Author)

  6. Spectroscopy of lithium atoms sublimated from isolation matrix of solid Ne.

    Science.gov (United States)

    Sacramento, R L; Scudeller, L A; Lambo, R; Crivelli, P; Cesar, C L

    2011-10-07

    We have studied, via laser absorption spectroscopy, the velocity distribution of (7)Li atoms released from a solid neon matrix at cryogenic temperatures. The Li atoms are implanted into the Ne matrix by laser ablation of a solid Li precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms at around 12 K. We find interesting differences in the velocity distribution of the released Li atoms from the model developed for our previous experiment with Cr [R. Lambo, C. C. Rodegheri, D. M. Silveira, and C. L. Cesar, Phys. Rev. A 76, 061401(R) (2007)]. This may be due to the sublimation regime, which is at much lower flux for the Li experiment than for the Cr experiment, as well as to the different collisional cross sections between those species to the Ne gas. We find a drift velocity compatible with Li being thermally sublimated at 11-13 K, while the velocity dispersion around this drift velocity is low, around 5-7 K. With a slow sublimation of the matrix we can determine the penetration depth of the laser ablated Li atoms into the Ne matrix, an important information that is not usually available in most matrix isolation spectroscopy setups. The present results with Li, together with the previous results with Cr suggest this to be a general technique for obtaining cryogenic atoms, for spectroscopic studies, as well as for trap loading. The release of the isolated atoms is also a useful tool to study and confirm details of the matrix isolated atoms which are masked or poorly understood in the solid. © 2011 American Institute of Physics

  7. Environmental and health effects review for obscurant graphite flakes. Final report, 1991 July--1993 May

    Energy Technology Data Exchange (ETDEWEB)

    Driver, C.J.; Ligotke, M.W.; Landis, W.G.; Downs, J.L.; Tiller, B.L.; Moore, E.B. Jr.; Cataldo, D.A.

    1993-07-01

    The health and environmental effects of obscurant graphite flakes were reviewed and compared to predicted levels of graphite flake material in the field during typical testing and training scenarios. Graphite flake dispersion and deposition for simulated mechanical and pyrotechnic releases were determined using a modified Gaussian atmospheric plume-dispersion model. The potential for wind resuspension of graphite flakes is controlled by weathering processes and incorporation rates in soil. Chemically, graphite flakes pose little risk to aquatic or terrestrial systems. Mechanical damage to plants and invertebrate and vertebrate organisms from the flakes is also minimal. In humans, the pathological and physiological response to inhaled graphite flake is similar to that induced by nuisance dusts and cause only transient pulmonary changes. Repeated exposure to very high concentrations (such as those near the source generator) may overwhelm the clearance mechanisms of the lung and result in pulmonary damage from the retained particles in unprotected individuals. However, these lesions either resolve with time or are of limited severity. Health effects of mixed aerosols of mixed aerosols of graphite and fog oil are similar to those produced by graphite flakes alone. Environmental impacts of fog oil-coated graphite flakes are not well known.

  8. Kinetics of Chronic Oxidation of NBG-17 Nuclear Graphite by Water Vapor

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burchell, Timothy D [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert [Univ. of Tennessee, Knoxville, TN (United States)

    2015-05-01

    This report presents the results of kinetic measurements during accelerated oxidation tests of NBG-17 nuclear graphite by low concentration of water vapor and hydrogen in ultra-high purity helium. The objective is to determine the parameters in the Langmuir-Hinshelwood (L-H) equation describing the oxidation kinetics of nuclear graphite in the helium coolant of high temperature gas-cooled reactors (HTGR). Although the helium coolant chemistry is strictly controlled during normal operating conditions, trace amounts of moisture (predictably < 0.2 ppm) cannot be avoided. Prolonged exposure of graphite components to water vapor at high temperature will cause very slow (chronic) oxidation over the lifetime of graphite components. This behavior must be understood and predicted for the design and safe operation of gas-cooled nuclear reactors. The results reported here show that, in general, oxidation by water of graphite NBG-17 obeys the L-H mechanism, previously documented for other graphite grades. However, the characteristic kinetic parameters that best describe oxidation rates measured for graphite NBG-17 are different than those reported previously for grades H-451 (General Atomics, 1978) and PCEA (ORNL, 2013). In some specific conditions, certain deviations from the generally accepted L-H model were observed for graphite NBG-17. This graphite is manufactured in Germany by SGL Carbon Group and is a possible candidate for the fuel elements and reflector blocks of HTGR.

  9. Thermal Pyrolytic Graphite Enhanced Components

    Science.gov (United States)

    Hardesty, Robert E. (Inventor)

    2015-01-01

    A thermally conductive composite material, a thermal transfer device made of the material, and a method for making the material are disclosed. Apertures or depressions are formed in aluminum or aluminum alloy. Plugs are formed of thermal pyrolytic graphite. An amount of silicon sufficient for liquid interface diffusion bonding is applied, for example by vapor deposition or use of aluminum silicon alloy foil. The plugs are inserted in the apertures or depressions. Bonding energy is applied, for example by applying pressure and heat using a hot isostatic press. The thermal pyrolytic graphite, aluminum or aluminum alloy and silicon form a eutectic alloy. As a result, the plugs are bonded into the apertures or depressions. The composite material can be machined to produce finished devices such as the thermal transfer device. Thermally conductive planes of the thermal pyrolytic graphite plugs may be aligned in parallel to present a thermal conduction path.

  10. Influence of graphite-alloy interactions on corrosion of Ni-Mo-Cr alloy in molten fluorides

    Science.gov (United States)

    Ai, Hua; Hou, Juan; Ye, Xiang-Xi; Zeng, Chao Liu; Sun, Hua; Li, Xiaoyun; Yu, Guojun; Zhou, Xingtai; Wang, Jian-Qiang

    2018-05-01

    In this study, the effects of graphite-alloy interaction on corrosion of Ni-Mo-Cr alloy in molten FLiNaK salt were investigated. The corrosion tests of Ni-Mo-Cr alloys were conducted in graphite crucibles, to examine the differences of test specimens in conditions of electric contact and isolated with graphite, respectively. The corrosion attack is severer with more weight loss and deeper Cr depletion layer in samples electric contact with graphite than those isolated with graphite. The occurrence of galvanic corrosion between alloy specimens and graphite container was confirmed by electrochemical measurement. The corrosion is controlled by nonelectric transfer in isolated test while electrochemical reaction accelerated corrosion in electric contact test.

  11. New Perspectives on Blowing Snow Transport, Sublimation, and Layer Thermodynamic Structure over Antarctica

    Science.gov (United States)

    Palm, Steve; Kayetha, Vinay; Yang, Yuekui; Pauly, Rebecca M.

    2017-01-01

    Blowing snow over Antarctica is a widespread and frequent event. Satellite remote sensing using lidar has shown that blowing snow occurs over 70% of the time over large areas of Antarctica in winter. The transport and sublimation of blowing snow are important terms in the ice sheet mass balance equation and the latter is also an important part of the hydrological cycle. Until now the only way to estimate the magnitude of these processes was through model parameterization. We present a technique that uses direct satellite observations of blowing snow and model (MERRA-2) temperature and humidity fields to compute both transport and sublimation of blowing snow over Antarctica for the period 2006 to 2016. The results show a larger annual continent-wide integrated sublimation than current published estimates and a significant transport of snow from continent to ocean. The talk will also include the lidar backscatter structure of blowing snow layers that often reach heights of 200 to 300 m as well as the first dropsonde measurements of temperature, moisture and wind through blowing snow layers.

  12. Vapor pressures and sublimation enthalpies of seven heteroatomic aromatic hydrocarbons measured using the Knudsen effusion technique

    International Nuclear Information System (INIS)

    Goldfarb, Jillian L.; Suuberg, Eric M.

    2010-01-01

    The vapor pressures of seven heteroatom-containing cyclic aromatic hydrocarbons, ranging in molecular weight from (168.19 to 208.21) g . mol -1 were measured over the temperature range of (301 to 486) K using the isothermal Knudsen effusion technique. The compounds measured include: anthraquinone, 9-fluorenone, 9-fluorenone oxime, phenoxazine, phenoxathiin, and 9H-pyrido[3,4-b]indole. These solid-state sublimation measurements provided values that are compared to vapor pressures of parent aromatic compounds (anthracene and fluorene) and to others with substituent groups in order to examine the effects of alcohol, ketone, pyridine, and pyrrole functionality on this property. The enthalpies and entropies of sublimation for each compound were determined from the Clausius-Clapeyron equation. Though there is no consistent trend in terms of the effects of substitutions on changes in the enthalpy or entropy of sublimation, we note that the prevalence of enthalpic or entropic driving forces on vapor pressure depend on molecule-specific factors and not merely molecular weight of the substituents.

  13. Vapor pressures and sublimation enthalpies of seven heteroatomic aromatic hydrocarbons measured using the Knudsen effusion technique

    Energy Technology Data Exchange (ETDEWEB)

    Goldfarb, Jillian L., E-mail: JillianLGoldfarb@gmail.co [Division of Engineering, Brown University, Providence, RI 02912 (United States); Suuberg, Eric M., E-mail: Eric_Suuberg@brown.ed [Division of Engineering, Brown University, Providence, RI 02912 (United States)

    2010-06-15

    The vapor pressures of seven heteroatom-containing cyclic aromatic hydrocarbons, ranging in molecular weight from (168.19 to 208.21) g . mol{sup -1} were measured over the temperature range of (301 to 486) K using the isothermal Knudsen effusion technique. The compounds measured include: anthraquinone, 9-fluorenone, 9-fluorenone oxime, phenoxazine, phenoxathiin, and 9H-pyrido[3,4-b]indole. These solid-state sublimation measurements provided values that are compared to vapor pressures of parent aromatic compounds (anthracene and fluorene) and to others with substituent groups in order to examine the effects of alcohol, ketone, pyridine, and pyrrole functionality on this property. The enthalpies and entropies of sublimation for each compound were determined from the Clausius-Clapeyron equation. Though there is no consistent trend in terms of the effects of substitutions on changes in the enthalpy or entropy of sublimation, we note that the prevalence of enthalpic or entropic driving forces on vapor pressure depend on molecule-specific factors and not merely molecular weight of the substituents.

  14. A analítica kantiana do sublime em Friedrich Schiller

    Directory of Open Access Journals (Sweden)

    Artur Bispo dos Santos Neto

    2016-10-01

    Full Text Available O nosso texto tem como propósito apontar a articulação existente entre a estética kantiana, expressa na sua obra basilar Crítica da faculdade do juízo, e a reflexão estética constituída por Friedrich Schiller mediante a sua noção de sublime. Embora Schiller se inscreva sob o signo da influência da terceira Crítica, vamos mostrar na tessitura deste texto como consegue libertar-se da influência kantiana, ao recusar a centralidade do juízo de gosto na definição do belo e afirmar a beleza (puchritudo como liberdade no fenômeno. Schiller não se limita à investigação do sublime no âmbito da beleza livre (natureza, mas investiga-a especialmente no campo da beleza aderente. Embora o próprio Kant tenha atribuído ao gosto o significado de uma transição do prazer dos sentidos à disposição moral, será Schiller quem radicalizará o propósito de uma educação moral do homem pela mediação do sublime e do patético na arte.

  15. Application of a Kalman filter to UF6 gaseous diffusion plant freezer/sublimer systems

    International Nuclear Information System (INIS)

    Ruppel, F.R.

    1992-03-01

    A signal is required to control the flow of UF 6 in gaseous diffusion plant freezer/sublimer systems. The original strategy envisioned for deriving a flow signal was to take the derivative of the freezer/sublimer weigh cell signal. However, the derivative of the digitized weight signal is noisy, preventing good control. In addition, a bias is introduced into the weight derivative signal because a refrigerant is circulated through a shell-and-tube heat exchanger inside the freezer/sublimer. The weight of the refrigerant is included in the weight measured by the weigh cell. If the circulation rate of the refrigerent is not steady state, a bias exists. Measurements of upstream pressure, vessel pressure, and output to the system control valve are available to the control system. Thus, if the flow through the control valve is characterized properly by the measurements, a Kalman filter can be used in conjunction with these auxiliary inputs and the weigh cell input to overcome the noise and bias problem and provide an improve estimate of flow rate. A discussion of the development and the current status of a Kalman filter used for this application is given. 5 refs

  16. GROTESQUE ENCOUNTERS: READING SHAKESPEARE’S THE MERCHANT OF VENICE ALONG THE PRINCIPLES OF THE SUBLIME, BEAUTIFUL AND GROTESQUE

    Directory of Open Access Journals (Sweden)

    Kathrin Bartha

    2015-12-01

    Full Text Available This article is an attempt to apply the basic principles of the aesthetic discourse on the sublime, beautiful and grotesque to William Shakespeare's The Merchant of Venice. Even though it is a discourse that only begins in the course of the eighteenth century, I will argue that the structure of the play parallels the model of the traditional sublime, as it deals with a subject-object binary and meditates on the relationship between the material (body and the transcendental (mind. However, the play is also rich in disruptive — or grotesque — forces that unsettle this binary structure. The parallels between the play and the aesthetic discourse could not only help our understanding of postmodern criticism and rewriting of the sublime, but the sublime can also, in turn, shed light on the reception of the play.

  17. Shades of Grey: The Role of the Sublime in the Memorial to the Murdered Jews of Europe

    Directory of Open Access Journals (Sweden)

    Karen Wilson Baptist

    2012-12-01

    Full Text Available As a ‘post-disaster’ landscape, the Memorial to the Murdered Jews of Europe does, arguably, occupy ground where the mass extermination of the Jewish people of Europe was masterminded, but it is not physically a site of death. Commonly, memorial landscapes are erected upon the location where violence, tragedy and disaster have occurred. Divorced from the diasporic dead it seeks to honour, the memorial employs spatial form, the surrounding atmosphere and human memory to potentialise a sublime experience for visitors. The sublime plays an essential role in memorial landscapes because sublime experiences are heightened, unforgettable and enduring. This reduces the possibility that visitors will depart the memorial unscathed, leaving the monument to bear the burden of memory. While a sublime experience can be optimised, it cannot be given, thus, the onus of remembering the Holocaust remains our responsibility.

  18. Raman characterization of bulk ferromagnetic nanostructured graphite

    International Nuclear Information System (INIS)

    Pardo, Helena; Divine Khan, Ngwashi; Faccio, Ricardo; Araújo-Moreira, F.M.; Fernández-Werner, Luciana

    2012-01-01

    Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm -1 showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.

  19. Fabrication of Graphene by Cleaving Graphite Chemically

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shu-hua; ZHAO Xiao-ting; FAN Hou-gang; YANG Li-li; ZHANG Yong-jun; YANG Jing-hai

    2011-01-01

    Graphite was chemically cleaved to graphene by Billups Reaction,and the morphologies and microstructures of graphene were characterized by SEM,Raman and AFM.The results show that the graphite was first functionalized by l-iodododecane,which led to the cleavage of the graphene layer in the graphite.The second decoration cleaved the graphite further and graphene was obtained.The heights of the graphene layer were larger than 1 nm due to the organic decoration.

  20. Method of Joining Graphite Fibers to a Substrate

    Science.gov (United States)

    Beringer, Durwood M. (Inventor); Caron, Mark E. (Inventor); Taddey, Edmund P. (Inventor); Gleason, Brian P. (Inventor)

    2014-01-01

    A method of assembling a metallic-graphite structure includes forming a wetted graphite subassembly by arranging one or more layers of graphite fiber material including a plurality of graphite fibers and applying a layer of metallization material to ends of the plurality of graphite fibers. At least one metallic substrate is secured to the wetted graphite subassembly via the layer of metallization material.

  1. Additive scheme for calculation of solvation enthalpies of heterocyclic aromatic compounds. Sublimation/vaporization enthalpy at 298.15 K

    International Nuclear Information System (INIS)

    Solomonov, Boris N.; Nagrimanov, Ruslan N.; Mukhametzyanov, Timur A.

    2016-01-01

    Highlights: • Additivity scheme for solvation enthalpies estimation of heteroaromatic compounds was proposed. • Method for determination of vaporization/sublimation enthalpies directly at 298.15 K was developed. • Solution enthalpies of 25 heteroaromatic compounds were measured. • Vaporization/sublimation enthalpies of 44 heteroaromatic compounds were determined. • Obtained values are in good agreement with the results of conventional methods. - Abstract: Hereby we propose a method for determination of vaporization and sublimation enthalpies of heterocyclic and carbonyl-containing aromatic compounds at 298.15 K. According to this method vaporization and sublimation enthalpies at 298.15 K are determined based on enthalpies of solvation and solution. Solvation enthalpies of heteroatomatic and carbonyl-containing compounds are calculated using an additive scheme from the solvation enthalpy of closest aromatic hydrocarbon and contributions related to the exchange of CH-groups of hydrocarbon with corresponding substituent atoms or groups. Measured solution enthalpies together with calculated solvation enthalpies allowed to calculate corresponding vaporization and sublimation enthalpies at 298.15 K for a large number of heterocyclic and carbonyl-containing compounds. We have also found that in a number of cases instead of solution enthalpy in benzene at 298.15 K fusion enthalpy at the melting temperature can be used. Comparison between literature data and calculated vaporization and sublimation enthalpies demonstrates satisfactory performance of the proposed method.

  2. Additive scheme for calculation of solvation enthalpies of heterocyclic aromatic compounds. Sublimation/vaporization enthalpy at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, Boris N., E-mail: boris.solomonov@kpfu.ru; Nagrimanov, Ruslan N.; Mukhametzyanov, Timur A.

    2016-06-10

    Highlights: • Additivity scheme for solvation enthalpies estimation of heteroaromatic compounds was proposed. • Method for determination of vaporization/sublimation enthalpies directly at 298.15 K was developed. • Solution enthalpies of 25 heteroaromatic compounds were measured. • Vaporization/sublimation enthalpies of 44 heteroaromatic compounds were determined. • Obtained values are in good agreement with the results of conventional methods. - Abstract: Hereby we propose a method for determination of vaporization and sublimation enthalpies of heterocyclic and carbonyl-containing aromatic compounds at 298.15 K. According to this method vaporization and sublimation enthalpies at 298.15 K are determined based on enthalpies of solvation and solution. Solvation enthalpies of heteroatomatic and carbonyl-containing compounds are calculated using an additive scheme from the solvation enthalpy of closest aromatic hydrocarbon and contributions related to the exchange of CH-groups of hydrocarbon with corresponding substituent atoms or groups. Measured solution enthalpies together with calculated solvation enthalpies allowed to calculate corresponding vaporization and sublimation enthalpies at 298.15 K for a large number of heterocyclic and carbonyl-containing compounds. We have also found that in a number of cases instead of solution enthalpy in benzene at 298.15 K fusion enthalpy at the melting temperature can be used. Comparison between literature data and calculated vaporization and sublimation enthalpies demonstrates satisfactory performance of the proposed method.

  3. Photoemission study of K on graphite

    NARCIS (Netherlands)

    Bennich, P.; Puglia, C.; Brühwiler, P.A.; Nilsson, A.; Sandell, A.; Mårtensson, N.; Rudolf, P.

    1999-01-01

    The physical and electronic structure of the dispersed and (2×2) phases of K/graphite have been characterized by valence and core-level photoemission. Charge transfer from K to graphite is found to occur at all coverages, and includes transfer of charge to the second graphite layer. A rigid band

  4. Separation medium containing thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

    2012-01-01

    A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

  5. NMR studies on graphite-methanol system

    International Nuclear Information System (INIS)

    El-Akkad, T.M.

    1977-01-01

    The nuclear magnetic relaxation times for protons of methanol on graphite have been studied. The perpendicular and the transversal magnetization as a function of temperature were measured. The results show that the presence of graphite slowed down the methanol movement compared with that in the pure alcohol, and that the methanol molecules are attached to the graphite surface via methyl groups. (author)

  6. Properties of screen-printed modified graphite layers

    Directory of Open Access Journals (Sweden)

    J. Walter

    2010-07-01

    Full Text Available During last years protection of the environment is one of the important problems that should be solved by modern technology. Theimportant problems are toxic gases emitted by conventional power plants. One of the methods that contribute to decreasing air pollution is manufacturing of cheap solar energy devices that could be applied in households. Among different type of fabrication technology of solar cells, DSSC technology looks like one of the interesting because it is relatively simple and low cost technology. Nowadays a lot of researcher groups making investigations to improve its setup, to get the cost reduction. The methods to achieve this goal were proposed in ISE (Germany as a concept of monolithic dye sensitised solar cell. One of the ideas of this solar cells setup is replacing expensive TCO electrode by much cheaper graphite electrode. Replacing TCO glass by graphite layer has to be done only in case of comparable properties of those both electrodes. There are some tested ideas of manufacturing that electrode and some of them are successfully applied. Presented work has been focused on preparation graphite conductive electrode for DSSC technology application, fabricated by screen–printing technique. Investigations concern new graphite past composition suitable for graphite layer preparation. It was been found that applying additive of titanium organic compound (Tyzor GBA to the past composition result in good properties, characterised by low resistance and good adhesion between graphite particles in the printed layer. Some tested layers prepared from proposed paste compositions characterised by better conductivity then applied in conventional DSSC cells counter electrode. The optimal addition of the modifier has not fixed yet.Among tested pastes the most promising results has been achieved for paste contained the biggest amount of Tyzor GBA.

  7. Gravity Effects on the Free Vibration of a Graphite Column

    International Nuclear Information System (INIS)

    Ki, Dong-Ok; Kim, Jong-Bum; Park, Keun-Bae; Lee, Won-Jae

    2006-01-01

    The gravity effects on the free vibration of a graphite column are studied. Graphite block is a key component of a HTGR (High Temperature Gas Cooled Reactor). The major core elements, such as the fuel blocks and neutron reflector blocks, of HTTR (High Temperature Test Reactor, Japan) and GT-MHR (Gas Turbine- Modular Helium Reactor, USA) consist of stacked hexagonal graphite blocks forming a group of columns. The vibration of the columns induced by earthquakes may lead to solid impacts between graphite blocks and structural integrity problems. The study of free vibration characteristics of the graphite block column is the first step in the core internal structure dynamic analysis. Gravity force bring a negative stiffness term to the transverse vibration analysis of heavy long column structures, and results in natural frequency reductions. Generally it is not considered in the not so tall structure cases, because the gravity term makes the analysis and design complicated. Therefore it is important to check whether the gravity effect is severe or not

  8. Data Report on the Newest Batch of PCEA Graphite for the VHTR Baseline Graphite Characterization Program

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Mark Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cottle, David Lynn [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rohrbaugh, David Thomas [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-08-01

    This report details a comparison of mechanical and physical properties from the first billet of extruded PCEA nuclear-grade graphite from the newest batch of PCEA procured from GrafTech. Testing has largely been completed on three of the billets from the original batch of PCEA, with data distributions for those billets exhibiting a much wider range of values when compared to the distributions of properties from other grades. A higher propensity for extremely low values or specimens that broke while machining or handling was also characteristic of the billets from the first batch, owing to unusually large fissures or disparate flaws in the billets in an as-manufactured state. Coordination with GrafTech prior to placing the order for a second batch of PCEA included discussions on these large disparate flaws and how to prevent them during the manufacturing process. This report provides a comparison of the observed data distributions from properties measured in the first billet from the new batch of PCEA with those observed in the original batch, in order that an evaluation of tighter control of the manufacturing process and the outcome of these controls on final properties can be ascertained. Additionally, this billet of PCEA is the first billet to formally include measurements from two alternate test techniques that will become part of the Baseline Graphite Characterization database – the three-point bend test on sub-sized cylinders and the Brazilian disc splitting tensile strength test. As the program moves forward, property distributions from these two tests will be based on specimen geometries that match specimen geometries being used in the irradiated Advanced Graphite Creep (AGC) program. This will allow a more thorough evaluation of both the utility of the test and expected variability in properties when using those approaches on the constrained geometries of specimens irradiated in the Advanced Test Reactor as part of the AGC experiment.

  9. Graphite to Inconel brazing using active filler metal

    International Nuclear Information System (INIS)

    King, J.F.; Baity, F.W.; Walls, J.C.; Hoffman, D.J.

    1989-01-01

    Ion cyclotron resonant frequency (ICRF) antennas are designed to supply large amounts of auxiliary heating power to fusion-grade plasmas in the Toroidal Fusion Test Reactor (TFTR) and Tore Supra fusion energy experiments. A single Faraday shield structure protects a pair of resonant double loops which are designed to launch up to 2 MW of power per loop. The shield consists of two tiers of actively cooled Inconel alloy tubes with the front tier being covered with semicircular graphite tiles. Successful operation of the antenna requires the making of high integrity bonds between the Inconel tubes and graphite tiles by brazing. This paper discusses this process

  10. Superconductivity in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert P. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Weller, Thomas E.; Howard, Christopher A. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Dean, Mark P.M. [Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rahnejat, Kaveh C. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Saxena, Siddharth S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ellerby, Mark, E-mail: mark.ellerby@ucl.ac.uk [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom)

    2015-07-15

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC{sub 6} and YbC{sub 6} in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  11. Superconductivity in graphite intercalation compounds

    International Nuclear Information System (INIS)

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P.M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-01-01

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC 6 and YbC 6 in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition

  12. Graphite oral tattoo: case report.

    Science.gov (United States)

    Moraes, Renata Mendonça; Gouvêa Lima, Gabriela de Morais; Guilhermino, Marinaldo; Vieira, Mayana Soares; Carvalho, Yasmin Rodarte; Anbinder, Ana Lia

    2015-10-16

    Pigmented oral lesions compose a large number of pathological entities, including exogenous pigmentat oral tattoos, such as amalgam and graphite tattoos. We report a rare case of a graphite tattoo on the palate of a 62-year-old patient with a history of pencil injury, compare it with amalgam tattoos, and determine the prevalence of oral tattoos in our Oral Pathology Service. We also compare the clinical and histological findings of grafite and amalgam tattoos. Oral tattoos affect women more frequently in the region of the alveolar ridge. Graphite tattoos occur in younger patients when compared with the amalgam type. Histologically, amalgam lesions represent impregnation of the reticular fibers of vessels and nerves with silver, whereas in cases of graphite tattoos, this impregnation is not observed, but it is common to observe a granulomatous inflammatory response, less evident in cases of amalgam tattoos. Both types of lesions require no treatment, but in some cases a biopsy may be done to rule out melanocytic lesions.

  13. 'In situ' expanded graphite extinguishant

    International Nuclear Information System (INIS)

    Cao Qixin; Shou Yuemei; He Bangrong

    1987-01-01

    This report is concerning the development of the extinguishant for sodium fire and the investigation of its extinguishing property. The experiment result shows that 'in situ' expanded graphite developed by the authors is a kind of extinguishant which extinguishes sodium fire quickly and effectively and has no environment pollution during use and the amount of usage is little

  14. Preliminary experiment design of graphite dust emission measurement under accident conditions for HTGR

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wei, E-mail: pengwei@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology of Tsinghua University, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 100084 (China); Chen, Tao; Sun, Qi; Wang, Jie [Institute of Nuclear and New Energy Technology of Tsinghua University, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 100084 (China); Yu, Suyuan, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, The Key Laboratory for Thermal Science and Power Engineering, Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2017-05-15

    Highlights: • A theoretical analysis is used to predict the total graphite dust release for an AVR LOCA. • Similarity criteria must be satisfied between the experiment and the actual HTGR system. • Model experiments should be conducted to predict the graphite dust resuspension rate. - Abstract: The graphite dust movement behavior is significant for the safety analyses of high-temperature gas cooled reactor (HTGR). The graphite dust release for accident conditions is an important source term for HTGR safety analyses. Depressurization release tests are not practical in HTGR because of a radioactivity release to the environment. Thus, a theoretical analysis and similarity principles were used to design a group of modeling experiments. Modeling experiments for fan start-up and depressurization process and actual experiments of helium circulator start-up in an HTGR were used to predict the rate of graphite dust resuspension and the graphite dust concentration, which can be used to predict the graphite dust release during accidents. The modeling experiments are easy to realize and the helium circulator start-up test does not harm the reactor system or the environment, so this experiment program is easily achieved. The revised Rock’n’Roll model was then used to calculate the AVR reactor release. The calculation results indicate that the total graphite dust releases during a LOCA will be about 0.65 g in AVR.

  15. Graphite nanoreinforcements in polymer nanocomposites

    Science.gov (United States)

    Fukushima, Hiroyuki

    Nanocomposites composed of polymer matrices with clay reinforcements of less than 100 nm in size, are being considered for applications such as interior and exterior accessories for automobiles, structural components for portable electronic devices, and films for food packaging. While most nanocomposite research has focused on exfoliated clay platelets, the same nanoreinforcement concept can be applied to another layered material, graphite, to produce nanoplatelets and nanocomposites. Graphite is the stiffest material found in nature (Young's Modulus = 1060 GPa), having a modulus several times that of clay, but also with excellent electrical and thermal conductivity. The key to utilizing graphite as a platelet nanoreinforcement is in the ability to exfoliate this material. Also, if the appropriate surface treatment can be found for graphite, its exfoliation and dispersion in a polymer matrix will result in a composite with not only excellent mechanical properties but electrical properties as well, opening up many new structural applications as well as non-structural ones where electromagnetic shielding and high thermal conductivity are requirements. In this research, a new process to fabricate exfoliated nano-scale graphite platelets was established (Patent pending). The size of the resulted graphite platelets was less than 1 um in diameter and 10 nm in thickness, and the surface area of the material was around 100 m2/g. The reduction of size showed positive effect on mechanical properties of composites because of the increased edge area and more functional groups attached with it. Also various surface treatment techniques were applied to the graphite nanoplatelets to improve the surface condition. As a result, acrylamide grafting treatment was found to enhance the dispersion and adhesion of graphite flakes in epoxy matrices. The resulted composites showed better mechanical properties than those with commercially available carbon fibers, vapor grown carbon fibers

  16. Reinforcement of cement-based matrices with graphite nanomaterials

    Science.gov (United States)

    Sadiq, Muhammad Maqbool

    micro-scale fibers were used for comparison purposes at different volume fractions. Replicated mixes and tests were considered to provide the basis for statistically reliable inferences. Theoretical studies were conducted in order to develop insight into the reinforcement mechanisms of properly functionalized graphite nanomaterials. The results suggested that modified graphite nanomaterials improve the mechanical performance of cement-based matrices primarily through control of microcrack size and propagation, relying on their close spacing within matrix and dissipation of substantial energy by debonding and frictional pullout over their enormous surface areas. The gains in barrier qualities of cement-based materials with introduction of modified graphite nanomaterials could be attributed to the increased tortuosity of diffusion paths in the presence of closely spaced nanomaterials. Experimental investigations were designed and implemented towards identification of the optimum (nano- and micro-scale) reinforcement systems for high-performance concrete through RSA (Response Surface Analysis). A comprehensive experimental data base was developed on the mechanical, physical and durability characteristics as well as the structure and composition of high-performance cementitious nanocomposites reinforced with modified graphite nanomaterials and/ or different micro-fibers.

  17. Development of a rotating graphite carbon disk stripper

    Science.gov (United States)

    Hasebe, Hiroo; Okuno, Hiroki; Tatami, Atsushi; Tachibana, Masamitsu; Murakami, Mutsuaki; Kuboki, Hironori; Imao, Hiroshi; Fukunishi, Nobuhisa; Kase, Masayuki; Kamigaito, Osamu

    2018-05-01

    Highly oriented graphite carbon sheets (GCSs) were successfully used as disk strippers. An irradiation test conducted in 2015 showed that GCS strippers have the longest lifetime and exhibit improved stripping and transmission efficiencies. The problem of disk deformation in previously used Be-disk was solved even with higher beam intensity.

  18. Characterisation of Chlorine Behavior in French Graphite

    International Nuclear Information System (INIS)

    Blondel, A.; Moncoffre, N.; Toulhoat, N.; Bererd, N.; Petit, L.; Laurent, G.; Lamouroux, C.

    2016-01-01

    Chlorine 36 is one of the main radionuclides of concern for French graphite waste disposal. In order to help the understanding of its leaching behaviour under disposal conditions, the respective impact of temperature, irradiation and gas radiolysis on chlorine release in reactor has been studied. Chlorine 36 has been simulated through chlorine 37 ion implantation in virgin nuclear graphite samples. Results show that part of chlorine is highly mobile in graphite in the range of French reactors operating temperatures in relation with graphite structural recovering. Ballistic damage generated by irradiation also promotes chlorine release whereas no clear impact of the coolant gas radiolysis was observed in the absence of graphite radiolytic corrosion. (author)

  19. Progress in radioactive graphite waste management

    International Nuclear Information System (INIS)

    2010-07-01

    Radioactive graphite constitutes a major waste stream which arises during the decommissioning of certain types of nuclear installations. Worldwide, a total of around 250 000 tonnes of radioactive graphite, comprising graphite moderators and reflectors, will require management solutions in the coming years. 14 C is the radionuclide of greatest concern in nuclear graphite; it arises principally through the interaction of reactor neutrons with nitrogen, which is present in graphite as an impurity or in the reactor coolant or cover gas. 3 H is created by the reactions of neutrons with 6 Li impurities in graphite as well as in fission of the fuel. 36 Cl is generated in the neutron activation of chlorine impurities in graphite. Problems in the radioactive waste management of graphite arise mainly because of the large volumes requiring disposal, the long half-lives of the main radionuclides involved and the specific properties of graphite - such as stored Wigner energy, graphite dust explosibility and the potential for radioactive gases to be released. Various options for the management of radioactive graphite have been studied but a generally accepted approach for its conditioning and disposal does not yet exist. Different solutions may be appropriate in different cases. In most of the countries with radioactive graphite to manage, little progress has been made to date in respect of the disposal of this material. Only in France has there been specific thinking about a dedicated graphite waste-disposal facility (within ANDRA): other major producers of graphite waste (UK and the countries of the former Soviet Union) are either thinking in terms of repository disposal or have no developed plans. A conference entitled 'Solutions for Graphite Waste: a Contribution to the Accelerated Decommissioning of Graphite Moderated Nuclear Reactors' was held at the University of Manchester 21-23 March 2007 in order to stimulate progress in radioactive graphite waste management

  20. Voronoi-Tessellated Graphite Produced by Low-Temperature Catalytic Graphitization from Renewable Resources.

    Science.gov (United States)

    Zhao, Leyi; Zhao, Xiuyun; Burke, Luke T; Bennett, J Craig; Dunlap, Richard A; Obrovac, Mark N

    2017-09-11

    A highly crystalline graphite powder was prepared from the low temperature (800-1000 °C) graphitization of renewable hard carbon precursors using a magnesium catalyst. The resulting graphite particles are composed of Voronoi-tessellated regions comprising irregular sheets; each Voronoi-tessellated region having a small "seed" particle located near their centroid on the surface. This suggests nucleated outward growth of graphitic carbon, which has not been previously observed. Each seed particle consists of a spheroidal graphite shell on the inside of which hexagonal graphite platelets are perpendicularly affixed. This results in a unique high surface area graphite with a high degree of graphitization that is made with renewable feedstocks at temperatures far below that conventionally used for artificial graphites. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Aluminum-graphite composite produced by mechanical milling and hot extrusion

    International Nuclear Information System (INIS)

    Flores-Zamora, M.I.; Estrada-Guel, I.; Gonzalez-Hernandez, J.; Miki-Yoshida, M.; Martinez-Sanchez, R.

    2007-01-01

    Aluminum-graphite composites were produced by mechanical milling followed by hot extrusion. Graphite content was varied between 0 and 1 wt.%. Al-graphite mixtures were initially mixed in a shaker mill without ball, followed by mechanical milling in a High-energy simoloyer mill for 2 h under argon atmosphere. Milled powders were subsequently pressed at ∼950 MPa for 2 min, and next sintered under vacuum for 3 h at 823 K. Finally, sintered products were held for 0.5 h at 823 K and hot extruded using indirect extrusion. Tension and compression tests were carried out to determine the yield stress and maximum stress of the materials. We found that the mechanical resistance increased as the graphite content increased. Microstructural characterization was done by transmission electron microscopy. Al-O-C nanofibers and graphite nanoparticles were observed in extruded samples by transmission electron microscopy. These nanoparticles and nanofibers seemed to be responsible of the reinforcement phenomenon

  2. Substitution of Acetylene Black by Using Modified Flake Graphite Applied in Activated Carbon Supercapacitors

    Directory of Open Access Journals (Sweden)

    Zhao Peng

    2018-01-01

    Full Text Available Flake graphite was mechanically modified at different times in N-methyl pyrrolidone under normal pressure. The results of the scanning electron microscopy, X-ray diffraction, and transmission electron microscopy suggested that the structure of the flake graphite was modified. The crystallinity of the flake graphite, and many defects were introduced into the material. The evaluation of capacitor performance by cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy was also performed. Results showed that the electrochemical performance of flake graphite was strongly enhanced, particularly when it was exfoliated for 6 h. Moreover, the electrochemical capacitive properties of activated carbon were obviously enhanced through the substitution of acetylene black by flake graphite modified for 6 h.

  3. Carbowaste: treatment and disposal of irradiated graphite and other carbonaceous waste

    International Nuclear Information System (INIS)

    Von Lensa, W.; Rizzato, C.; Baginski, K.; Banford, A.W.; Bradbury, D.; Goodwin, J.; Grambow, B.; Grave, M.J.; Jones, A.N.; Laurent, G.; Pina, G.; Vulpius, D.

    2014-01-01

    The European Project on 'Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste (CARBOWASTE)' addressed the retrieval, characterization, treatment, reuse and disposal of irradiated graphite with the following main results: - I-graphite waste features significantly depend on the specific manufacture process, on the operational conditions in the nuclear reactor (neutron dose, atmosphere, temperature etc.) and on radiolytic oxidation leading to partial releases of activation products and precursors during operation. - The neutron activation process generates significant recoil energies breaking pre-existing chemical bonds resulting in dislocations of activation products and new chemical compounds. - Most activation products exist in different chemical forms and at different locations. - I-graphite can be partly purified by thermal and chemical treatment processes leaving more leach-resistant waste products. - Leach tests and preliminary performance analyses show that i-graphite can be safely disposed of in a wide range of disposal systems, after appropriate treatment and/or conditioning. (authors)

  4. Time Variability of the Dust Sublimation Zones in Pre-Main Sequence Disk Systems

    Science.gov (United States)

    Sitko, Michael L.; Carpenter, W. J.; Grady, C. A.; Russel, R. W.; Lynch, D. K.; Rudy, R. J.; Mazuk, S. M.; Venturini, C. C.; Kimes, R. L.; Beerman, L. C.; hide

    2007-01-01

    The dust sublimation zone (DSZ) is the region of pre-main sequence (PMS) disks where dust grains most easily anneal, sublime, and condense out of the gas. Because of this, it is a location where crystalline material may be enhanced and redistributed throughout the rest of the disk. A decade-long program to monitor the thermal emission of the grains located in this region demonstrates that large changes in emitted flux occur in many systems. Changes in the thermal emission between 3 and 13.5 microns were observed in HD 31648 (MWC 480), HD 163296 (MWC 275), and DG Tau. This emission is consistent with it being produced at the DSZ, where the transition from a disk of gas to one of gas+dust occurs. In the case of DG Tau, the outbursts were accompanied by increased emission on the 10 micron silicate band on one occasion, while on another occasion it went into absorption. This requires lofting of the material above the disk into the line of sight. Such changes will affect the determination of the inner disk structure obtained through interferometry measurements, and this has been confirmed in the case of HD 163296. Cyclic variations in the heating of the DSZ will lead to the annealing of large grains, the sublimation of smaller grains, possibly followed by re-condensation as the zone enters a cooling phase. Lofting of dust above the disk plane, and outward acceleration by stellar winds and radiation pressure, can re-distribute the processed material to cooler regions of the disk, where cometesimals form. This processing is consistent with the detection of the preferential concentration of large crystalline grains in the inner few AU of PMS disks using interferometric spectroscopy with the VLTI.

  5. Origin and effective reduction of inversion domains in aluminum nitride grown by a sublimation method

    Science.gov (United States)

    Shigetoh, Keisuke; Horibuchi, Kayo; Nakamura, Daisuke

    2017-11-01

    Owing to the large differences in the chemical properties between Al and N polarities in aluminum nitride (AlN), the choice of the polar direction for crystal growth strongly affects not only the quality but also the shape (facet formation) of the grown crystal. In particular, N-polar (0 0 0 -1) has been considered to be a more preferable direction than Al-polar (0 0 0 1) for sublimation growth because compared to Al-polar (0 0 0 1), N-polar (0 0 0 -1) exhibits better stability at high growth rate (high supersaturation) conditions and enables easier lateral enlargement of the crystal. However, some critical growth conditions induce polarity inversion and hinder stable N-polar growth. Furthermore, the origin of the polarity inversion in AlN growth by the sublimation method is still unclear. To ensure stable N-polar growth without polarity inversion, the formation mechanism of the inversion domain during AlN sublimation growth must be elucidated. Therefore, herein, we demonstrate homoepitaxial growth on an N-polar seed and carefully investigate the obtained crystal that shows polarity inversion. Annular bright-field scanning transmission electron microscopy reveals that polarity is completely converted to the Al polarity via the formation of a 30 nm thick mixed polar layer (MPL) just above the seed. Moreover, three-dimensional atom probe tomography shows the segregation of the oxygen impurities in the MPL with a high concentration of about 3 atom%. Finally, by avoiding the incorporation of oxygen impurity into the crystal at the initial stage of the growth, we demonstrate an effective reduction (seven orders of magnitude) of the inversion domain boundary formation.

  6. Wasting the Future: The Technological Sublime, Communications Technologies, and E-waste

    Directory of Open Access Journals (Sweden)

    Sebine Label

    2012-08-01

    Full Text Available Literally speaking, e-waste is the future of communications. E-waste is the fastest growing waste stream in the world, much of it communications technologies from cell phones to laptops, televisions to peripherals. As a result of policies of planned obsolescence working computers, cell phones, and tablets are routinely trashed. One of the most powerful and enduring discourses associated with emerging technologies is the technological sublime, in which technology is seen as intellectually, emotionally, or spiritually transcendent. It comprises a contradictory impulse that elevates technology with an almost religious fervor, while simultaneously overlooking some of the consequences of industrialism, as well as ignoring the necessity of social, economic, and governmental infrastructures necessary to the implementation and development of new technologies. The idea that a new technology will not pollute or harm the environment is a persistent, though often quickly passed over, theme in the technological sublime, echoed in discourses about emerging technologies such as the silicon chip, the internet, and other ICTs. In this paper, I make connections between the discourse of newness, the practice of planned obsolescence, and the mountains of trashed components and devices globally. Considering the global context demonstrates the realities of the penetration of ICTs and their enduring pollution and negative implications for the health of humans and nonhumans, including plants, animals, waterways, soil, air and so on. I use the discourse of the technological sublime to open up and consider the future of communications, to argue that this discourse not only stays with us but also contains within it two important and related components, the promise of ecological harmony and a future orientation. I argue that these lingering elements keep us from considering the real future of communications – e-waste – and that, as communications scholars, we must also

  7. Preparation and characterization of copper-graphite composites by electrical explosion of wire in liquid.

    Science.gov (United States)

    Bien, T N; Gul, W H; Bac, L H; Kim, J C

    2014-11-01

    Copper-graphite nanocomposites containing 5 vol.% graphite were prepared by a powder metallurgy route using an electrical wire explosion (EEW) in liquid method and spark plasma sintering (SPS) process. Graphite rods with a 0.3 mm diameter and copper wire with a 0.2 mm diameter were used as raw materials for EEWin liquid. To compare, a pure copper and copper-graphite mixture was also prepared. The fabricated graphite was in the form of a nanosheet, onto which copper particles were coated. Sintering was performed at 900 degrees C at a heating rate of 30 degrees C/min for 10 min and under a pressure of 70 MPa. The density of the sintered composite samples was measured by the Archimedes method. A wear test was performed by a ball-on-disc tribometer under dry conditions at room temperature in air. The presence of graphite effectively reduced the wear of composites. The copper-graphite nanocomposites prepared by EEW had lower wear rates than pure copper material and simple mixed copper-graphite.

  8. The reaction of unirradiated and irradiated nuclear graphites with water vapor in helium

    International Nuclear Information System (INIS)

    Imai, Hisashi; Nomura, Shinzo; Kurosawa, Takeshi; Fujii, Kimio; Sasaki, Yasuichi

    1980-10-01

    Nuclear graphites more than 10 brands were oxidized with water vapor in helium and then some selected graphites were irradiated with fast neutron in the Japan Materials Testing Reactor to clarify the effect of radiation damage of graphite on their reaction behaviors. The reaction was carried out under a well defined condition in the temperature range 800 -- 1000 0 C at concentrations of water vapor 0.38 -- 1.30 volume percent in helium flow of total pressure of 1 atm. The chemical reactivity of graphite irradiated at 1000 +- 50 0 C increased linearly with neutron fluence until irradiation of 3.2 x 10 21 n/cm 2 . The activation energy for the reaction was found to decrease with neutron fluence for almost all the graphites, except for a few ones. The order of reaction increased from 0.5 for the unirradiated graphite to 1.0 for the graphite irradiated up to 6.0 x 10 20 n/cm 2 . Experiment was also performed to study a superposed effect between the influence of radiation damage of graphite and the catalytic action of barium on the reaction rate, as well as the effect of catalyser of barium. It was shown that these effects were not superposed upon each other, although barium had a strong catalytic action on the reaction. (author)

  9. Thermal conductivity enhancement of sodium acetate trihydrate by adding graphite powder and the effect on stability of supercooling

    DEFF Research Database (Denmark)

    Johansen, Jakob Berg; Dannemand, Mark; Kong, Weiqiang

    2015-01-01

    . The graphite powder was stabilized using carboxymetyl cellulose and successfully tested in heating and supercooling cycles with no loss of performance. Thermal conductivity enhancing properties of graphite powder was shown in samples. Since the experiments were conducted in small scale, at 200 g per sample......, large scale experiments are required to validate graphite as a thermo conductivity enhancing agent, suitable for use in seasonal heat storage applications utilizing SAT....

  10. A German research project about applicable graphite cutting techniques

    International Nuclear Information System (INIS)

    Holland, D.; Quade, U.; Bach, F.W.; Wilk, P.

    2001-01-01

    In Germany, too, quite large quantities of irradiated nuclear graphite, used in research and prototype reactors, are waiting for an environmental way of disposal. While incineration of nuclear graphite does not seem to be a publicly acceptable way, cutting and packaging into ductile cast iron containers could be a suitable way of disposal in Germany. Nevertheless, the cutting of graphite is also a very difficult technique by which a large amount of secondary waste or dust might occur. An applicable graphite cutting technique is needed. Therefore, a group of 13 German partners, consisting of one university, six research reactor operators, one technical inspection authority, three engineering companies, one industrial cutting specialist and one commercial dismantling company, decided in 1999 to start a research project to develop an applicable technique for cutting irradiated nuclear graphite. Aim of the project is to find the most suitable cutting techniques for the existing shapes of graphite blocks with a minimum of waste production rate. At the same time it will be learned how to sample the dust and collect it in a filter system. The following techniques will be tested and evaluated: thermal cutting, water jet cutting, mechanical cutting with a saw, plasma arc cutting, drilling. The subsequent evaluation will concentrate on dust production, possible irradiation of staff, time and practicability under different constraints. This research project is funded by the German Minister of Education and Research under the number 02 S 7849 for a period of two years. A brief overview about the work to be carried out in the project will be given. (author)

  11. Sublimation and thermal decomposition of ammonia borane: Competitive processes controlled by pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kondrat’ev, Yu.V.; Butlak, A.V.; Kazakov, I.V.; Timoshkin, A.Y., E-mail: a.y.timoshkin@spbu.edu

    2015-12-20

    Highlights: • We measured sublimation enthalpy of ammonia borane at 357 K by drop-calorimetry. • We determined activation energy for ammonia borane decomposition by tensimetry. • At 357 K decomposition and sublimation are competitive and depend on the pressure. • We propose new values for the Δ{sub f}H° of solid ammonia borane and polyamidoborane. - Abstract: Thermal behavior of ammonia borane BH{sub 3}NH{sub 3} (AB) has been studied by calorimetry, tensimetry and mass spectrometry methods. It is shown, that depending on vapor pressure in the system two competitive processes are taking place at 357 K. At atmospheric pressure thermal decomposition with hydrogen evolution is the dominant process: BH{sub 3}NH{sub 3(s)} = 1/n (BH{sub 2}NH{sub 2}){sub n(s)} + H{sub 2(g)} (1). At low pressures (circa 4 mTorr) the major process is endothermic sublimation of AB: BH{sub 3}NH{sub 3(s)} = BH{sub 3}NH{sub 3(g)} (2). At intermediate pressures both processes occur simultaneously. Enthalpies for the processes (1) and (2) have been determined by drop-calorimetry method: Δ{sub (1)}H{sub 357}° = −24.8 ± 2.3 kJ mol{sup −1} and Δ{sub sub}H{sub 357}°(BH{sub 3}NH{sub 3}) = 76.3 ± 3.0 kJ mol{sup −1}. Solid products after sublimation and decomposition have been characterized by IR and NMR spectroscopy; gaseous forms were studied by mass spectrometry. Activation energy of 94 ± 11 kJ mol{sup −1} for the process (1) in range 327–351 K was determined by static tensimetry method. Based on the analysis of available thermodynamic characteristics, new values for the standard formation enthalpy of solid AB −133.4 ± 5.2 kJ mol{sup −1} and polyamidoborane −156.7 ± 5.8 kJ mol{sup −1} are recommended.

  12. Thick epitaxial CdTe films grown by close space sublimation on Ge substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Q; Haliday, D P; Tanner, B K; Brinkman, A W [Department of Physics, University of Durham. Science Site, Durham, DH1 3LE (United Kingdom); Cantwell, B J; Mullins, J T; Basu, A [Durham Scientific Crystals Ltd., NetPark, Thomas Wright Way, Sedgefield, County Durham, TS21 3FD (United Kingdom)], E-mail: Q.Z.Jiang@durham.ac.uk

    2009-01-07

    This paper reports, for the first time, the successful growth of 200 {mu}m thick CdTe films on mis-oriented Ge(1 0 0) substrates by a cost-effective optimized close space sublimation method. It is found that, as the thickness increases to a few hundred micrometres, subgrains are formed probably as a result of the large density of dislocations and strain within the initial interfacial layers. The films are of high quality (x-ray rocking curve width {approx}100 arcsec) and high resistance ({approx}10{sup 9} {omega} cm), and are thus candidates for x-ray and {gamma}-ray detectors. (fast track communication)

  13. Low-level precipitation sublimation on the coasts of East Antarctica

    Science.gov (United States)

    Grazioli, Jacopo; Genthon, Christophe; Madeleine, Jean-Baptiste; Lemonnier, Florentin; Gallée, Hubert; Krinner, Gerhard; Berne, Alexis

    2017-04-01

    The weather of East Antarctica is affected by the peculiar morphology of this large continent and by its isolation from the surroundings. The high-elevation interior of the continent, very dry in absolute terms, originates winds that can reach the coastal areas with very high speed and persistence in time. The absence of topographic barriers and the near-ground temperature inversion allow these density-driven air movements to fall from the continent towards the coasts without excessive interaction and mixing with the atmosphere aloft. Thus, the air remains dry in absolute terms, and very dry in relative terms because of the higher temperatures near the coast and the adiabatic warming due to the descent. The coasts of Antarctica are less isolated and more exposed to incoming moist air masses than the rest of the continent, and precipitation in the form of snowfall more frequently occurs. Through its descent, however, snowfall encounters the layer of dry air coming from the continent and the deficit in humidity can lead to the partial or complete sublimation of the precipitating flux. This phenomenon is named here LPS (Low-level Precipitation Sublimation) and it has been observed by means of ground-based remote sensing instruments (weather radars) and atmospheric radio-sounding balloons records in the framework of the APRES3 campaign (Antarctic Precipitation: REmote Sensing from Surface and Space) in the coastal base of Dumont d' Urville (Terre Adélie), and then examined at the continental scale thanks to numerical weather models. LPS occurs over most of the coastal locations, where the total sublimated snowfall can be a significant percentage of the total snowfall. For example, in Dumont d' Urville the total yearly snowfall at 341 m height is less than 80% of the snowfall at 941 m height (the height of maximum yearly accumulation), and at shorter time scales complete sublimation (i.e. virga) often occurs. At the scale of individual precipitation events, LPS is

  14. Induced Recrystallization of CdTe Thin Films Deposited by Close-Spaced Sublimation

    International Nuclear Information System (INIS)

    Mayo, B.

    1998-01-01

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl2 treatment at 350C and completely recrystallized after the same treatment at 400C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl2 are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures

  15. Effect of the Heat Treatment on the Graphite Matrix of Fuel Element for HTGR

    International Nuclear Information System (INIS)

    Lee, Chungyong; Lee, Seungjae; Suh, Jungmin; Jo, Youngho; Lee, Youngwoo; Cho, Moonsung

    2013-01-01

    In this paper, the cylinder-formed fuel element for the block type reactor is focused on, which consists of the large part of graphite matrix. One of the most important properties of the graphite matrix is the mechanical strength for the high reliability because the graphite matrix should be enabled to protect the TRISO particles from the irradiation environment and the impact from the outside. In this study, the three kinds of candidate graphites and Phenol as a binder were chosen and mixed with each other, formed and heated for the compressive strength test. The objective of this research is to optimize the kinds and composition of the mixed graphite and the forming process by evaluating the compressive strength before/after heat treatment (carbonization of binder). In this study, the effect of heat treatment on graphite matrix was studied in terms of the density and the compressive strength. The size (diameter and length) of pellet is increased by heat treatment. Due to additional weight reduction and swelling (length and diameter) of samples the density of graphite pellet is decreased from about 2.0 to about 1.7g/cm 3 . From the mechanical test results, the compressive strength of graphite pellets was related to the various conditions such as the contents of binder, the kinds of graphite and the heat treatment. Both the green pellet and the heat treated pellet, the compressive strength of G+S+P pellets is relatively higher than that of R+S+P pellets. To optimize fuel element matrix, the effect of Phenol and other binders, graphite composition and the heat treatment on the mechanical properties will be deeply investigated for further study

  16. Studies on the behavior of graphite structures irradiated in the Dragon Reactor. Dragon Project report

    Energy Technology Data Exchange (ETDEWEB)

    Everett, M. R.; Graham, L. W.; Ridealgh, F.

    1971-11-15

    Design data for the physical and mechanical property changes which occur in graphite structural and fuel body components irradiated in an HTR are largely obtained from small specimens tested in the laboratory and in materials test reactors. A brief data summary is given. This graphite physics data can be used to predict dimensional changes, internal stress generation and strength changes in the graphite materials of HTR fuel elements irradiated in the Dragon Reactor. In this paper, the results which have been obtained from post-irradiation examination of a number of fuel pins, are compared with prediction.

  17. Graphite moderated 252Cf source

    International Nuclear Information System (INIS)

    Sajo B, L.; Barros, H.; Greaves, E. D.; Vega C, H. R.

    2014-08-01

    The thorium molten salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid fuel reactor. The neutron source to run this subcritical reactor is a 252 Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the 252 Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator. (Author)

  18. Fission Product Sorptivity in Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Tompson, Jr., Robert V. [Univ. of Missouri, Columbia, MO (United States); Loyalka, Sudarshan [Univ. of Missouri, Columbia, MO (United States); Ghosh, Tushar [Univ. of Missouri, Columbia, MO (United States); Viswanath, Dabir [Univ. of Missouri, Columbia, MO (United States); Walton, Kyle [Univ. of Missouri, Columbia, MO (United States); Haffner, Robert [Univ. of Missouri, Columbia, MO (United States)

    2015-04-01

    Both adsorption and absorption (sorption) of fission product (FP) gases on/into graphite are issues of interest in very high temperature reactors (VHTRs). In the original proposal, we proposed to use packed beds of graphite particles to measure sorption at a variety of temperatures and to use an electrodynamic balance (EDB) to measure sorption onto single graphite particles (a few μm in diameter) at room temperature. The use of packed beds at elevated temperature is not an issue. However, the TPOC requested revision of this initial proposal to included single particle measurements at elevated temperatures up to 1100 °C. To accommodate the desire of NEUP to extend the single particle EDB measurements to elevated temperatures it was necessary to significantly revise the plan and the budget. These revisions were approved. In the EDB method, we levitate a single graphite particle (the size, surface characteristics, morphology, purity, and composition of the particle can be varied) or agglomerate in the balance and measure the sorption of species by observing the changes in mass. This process involves the use of an electron stepping technique to measure the total charge on a particle which, in conjunction with the measured suspension voltages for the particle, allows for determinations of mass and, hence, of mass changes which then correspond to measurements of sorption. Accommodating elevated temperatures with this type of system required a significant system redesign and required additional time that ultimately was not available. These constraints also meant that the grant had to focus on fewer species as a result. Overall, the extension of the original proposed single particle work to elevated temperatures added greatly to the complexity of the proposed project and added greatly to the time that would eventually be required as well. This means that the bulk of the experimental progress was made using the packed bed sorption systems. Only being able to recruit one

  19. Graphite suspension in carbon dioxide; Suspension de graphite dans le gaz carbonique

    Energy Technology Data Exchange (ETDEWEB)

    Roche, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Moussez, C; Rouvillois, X; Brevet, R [Societe Nationale d' Etude et de Construction de Moteurs d' Aviation (SNECMA), 75 - Paris (France)

    1965-07-01

    Since 1963 the Atomic Division of SNECMA has been conducting, under a contract with the CEA, an experimental work with a two-component fluid comprised of carbon dioxide and small graphite particles. The primary purpose was the determination of basic engineering information pertaining to the stability and the flowability of the suspension. The final form of the experimental loop consists mainly of the following items: a light-phase compressor, a heavy-phase pump, an electrical-resistance type heater section, a cooling heat exchanger, a hairpin loop, a transparent test section and a separator. During the course of the testing, it was observed that the fluid could be circulated quite easily in a broad range of variation of the suspension density and velocity - density from 30 to 170 kg/m{sup 3} and velocity from 2 to 24 m/s. The system could be restarted and circulation maintained without any difficulty, even with the heavy-phase pump alone. The graphite did not have a tendency to pack or agglomerate during operation. No graphite deposition was observed on the wall of the tubing. A long period run (250 hours) has shown the evolution of the particle dimensions. Starting with graphite of surface area around 20 m{sup 2}/g (graphite particles about 1 {mu}), the powder surface area reaches an asymptotic value of 300 m{sup 2}/g (all the particles less than 0.3 {mu}). Moisture effect on flow stability, flow distribution between two parallel channels, pressure drop in straight tubes, recompression ratio in diffusers were also investigated. (author) [French] Depuis 1963 la Division Atomique de la SNECMA conduit, dans le cadre d'un contrat avec le Commissariat A l'Energie Atomique, l'etude experimentale d'une suspension de fines particules de graphite dans le gaz carbonique. L'objectif principal est d'obtenir des informations d'ordre mecanique et technologique sur la mise en oeuvre de l'ecoulement de ce fluide diphase. Le circuit experimental comprend principalement: un

  20. Simulation of wind-induced snow transport and sublimation in alpine terrain using a fully coupled snowpack/atmosphere model

    Science.gov (United States)

    Vionnet, V.; Martin, E.; Masson, V.; Guyomarc'h, G.; Naaim-Bouvet, F.; Prokop, A.; Durand, Y.; Lac, C.

    2014-03-01

    In alpine regions, wind-induced snow transport strongly influences the spatio-temporal evolution of the snow cover throughout the winter season. To gain understanding on the complex processes that drive the redistribution of snow, a new numerical model is developed. It directly couples the detailed snowpack model Crocus with the atmospheric model Meso-NH. Meso-NH/Crocus simulates snow transport in saltation and in turbulent suspension and includes the sublimation of suspended snow particles. The coupled model is evaluated against data collected around the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps). First, 1-D simulations show that a detailed representation of the first metres of the atmosphere is required to reproduce strong gradients of blowing snow concentration and compute mass exchange between the snowpack and the atmosphere. Secondly, 3-D simulations of a blowing snow event without concurrent snowfall have been carried out. Results show that the model captures the main structures of atmospheric flow in alpine terrain. However, at 50 m grid spacing, the model reproduces only the patterns of snow erosion and deposition at the ridge scale and misses smaller scale patterns observed by terrestrial laser scanning. When activated, the sublimation of suspended snow particles causes a reduction of deposited snow mass of 5.3% over the calculation domain. Total sublimation (surface + blowing snow) is three times higher than surface sublimation in a simulation neglecting blowing snow sublimation.

  1. An investigation on the mechanism of sublimed DHB matrix on molecular ion yields in SIMS imaging of brain tissue.

    Science.gov (United States)

    Dowlatshahi Pour, Masoumeh; Malmberg, Per; Ewing, Andrew

    2016-05-01

    We have characterized the use of sublimation to deposit matrix-assisted laser desorption/ionization (MALDI) matrices in secondary ion mass spectrometry (SIMS) analysis, i.e. matrix-enhanced SIMS (ME-SIMS), a common surface modification method to enhance sensitivity for larger molecules and to increase the production of intact molecular ions. We use sublimation to apply a thin layer of a conventional MALDI matrix, 2,5-dihydroxybenzoic acid (DHB), onto rat brain cerebellum tissue to show how this technique can be used to enhance molecular yields in SIMS while still retaining a lateral resolution around 2 μm and also to investigate the mechanism of this enhancement. The results here illustrate that cholesterol, which is a dominant lipid species in the brain, is decreased on the tissue surface after deposition of matrix, particularly in white matter. The decrease of cholesterol is followed by an increased ion yield of several other lipid species. Depth profiling of the sublimed rat brain reveals that the lipid species are de facto extracted by the DHB matrix and concentrated in the top most layers of the sublimed matrix. This extraction/concentration of lipids directly leads to an increase of higher mass lipid ion yield. It is also possible that the decrease of cholesterol decreases the potential suppression of ion yield caused by cholesterol migration to the tissue surface. This result provides us with significant insights into the possible mechanisms involved when using sublimation to deposit this matrix in ME-SIMS.

  2. Bearingless helicopter main rotor development. Volume 2: Combined load fatigue evaluation of weathered graphite/epoxy composite

    Science.gov (United States)

    Rackiewicz, J. J.

    1977-01-01

    Small scale combined load fatigue tests were conducted on six artificially and six naturally weathered test specimens. The test specimen material was unidirectionally oriented A-S graphite - woven glass scrim epoxy resin laminate.

  3. Graphite curtain vacuum outgassing and heat transfer. Final report

    International Nuclear Information System (INIS)

    Fivel, H.J.; Lang, G.P.; Kipp, H.W.

    1976-12-01

    Thermal conductivity of a bundle of high conductivity graphite fibers (T-50) was measured as a function of temperature, density and fiber orientation at pressures of 10 -4 to 10 -5 torr. All 3 variables had a significant influence on thermal conductivity. The highest conductivity fiber bundle tested had a conductivity significantly less than dense, bulk nuclear grade graphite. The incorporation of heat pipes into a graphite spectral shaper will permit a 2-fold thicker shaper. Heat pipes not only increase the transport of heat within the spectral shaper but can increase heat transfer at the shaper-first wall interface and potentially serve as a means of attaching shaper modules to the first wall. A heat pipe using a liquid metal working fluid was fabricated and tested in magnetic fields of 1 and 2 Tesla. Liquid metal heat pipes can be used in a magnetic field of at least up to 2 Tesla. Much more work needs to be done to establish the capabilities for high performance heat pipes when used in magnetic fields. Four different types of graphite fibers were exposed in EBR-II to a neutron fluence of 3.5 x 10 21 cm -2 EFF at 470 0 C. Large axial shrinkages of 6.6 to 8.6% resulted

  4. The graphite ball detector

    International Nuclear Information System (INIS)

    Renaud, P.W.

    1975-01-01

    This work presents the design and the practical testing of a comparatively cheap measuring system for the nuclear Doppler effect in an easily variable neutron spectrum. Samples of any kind of material can be measured and even a very simple thermal nuclear reactor with irradiation facilities will be a good neutron source, the gradient of the spectrum of which can be adapted by filtering techniques. Without experiments to confirm this, it may be stated, however, that the system can also be applied when a fast reactor system or other powerful neutron source is used. (Auth.)

  5. Microstructural characteristics, mechanical and wear behaviour of aluminium matrix hybrid composites reinforced with alumina, rice husk ash and graphite

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo Alaneme

    2015-09-01

    Full Text Available The microstructural characteristics, mechanical and wear behaviour of Aluminium matrix hybrid composites reinforced with alumina, rice husk ash (RHA and graphite were investigated. Alumina, RHA and graphite mixed in varied weight ratios were utilized to prepare 10 wt% hybrid reinforced Al-Mg-Si alloy based composites using two-step stir casting. Hardness, tensile properties, scanning electron microscopy, and wear tests were used to characterize the composites produced. The results show that Hardness decreases with increase in the weight ratio of RHA and graphite in the composites; and with RHA content greater than 50%, the effect of graphite on the hardness becomes less significant. The tensile strength for the composites containing o.5wt% graphite and up to 50% RHA was observed to be higher than that of the composites without graphite. The toughness values for the composites containing 0.5wt% graphite were in all cases higher than that of the composites without graphite. The % Elongation for all composites produced was within the range of 10–13% and the values were invariant to the RHA and graphite content. The tensile fracture surface morphology in all the composites produced was identical characterized with the presence of reinforcing particles housed in ductile dimples. The composites without graphite exhibited greater wear susceptibility in comparison to the composite grades containing graphite. However the wear resistance decreased with increase in the graphite content from 0.5 to 1.5 wt%.

  6. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    Science.gov (United States)

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  7. Experimental and molecular dynamics simulation study of the sublimation energetics of cyclopentadienyltricarbonylmanganese (Cymantrene).

    Science.gov (United States)

    Picciochi, Ricardo; Canongia Lopes, José N; Diogo, Hermínio P; Minas da Piedade, Manuel E

    2008-10-16

    The standard molar enthalpy of sublimation of monoclinic cyclopentadienyltricarbonylmanganese, Mn(eta (5)-C 5H 5)(CO) 3, at 298.15 K, was determined as Delta sub H m (o)[Mn(eta (5)-C 5H 5)(CO) 3] = 75.97 +/- 0.37 kJ x mol (-1) from Knudsen effusion and Calvet-drop microcalorimetry measurements, thus considerably improving the very large inaccuracy (>10 kJ x mol (-1)) of the published data. The obtained value was used to assess the extension of the OPLS-based all-atom force field we previously developed for iron metallocenes to manganese organometallic compounds. The modified force field was able to reproduce the volumetric properties (density and unit-cell volume) of crystalline Mn(eta (5)-C 5H 5)(CO) 3 with a deviation of 0.6% and the experimentally determined enthalpy of sublimation with an accuracy of 1 kJ x mol (-1). The interaction (epsilon) and atomic-diameter (sigma) parameters of the Lennard-Jones (12-6) potential function used to calculate dispersion contributions within the framework of the force field were found to be transferable from iron to manganese.

  8. Verdad sublime y madre asesina en Christine V., versión de Marguerite Duras

    Directory of Open Access Journals (Sweden)

    Juliana González Holguín

    2016-01-01

    Full Text Available Todo relato es ficción, versión y, así mismo, verdad, bajo una u otra concepción de la misma, es decir, desde una perspectiva que se enfoca según la intención y la subjetividad de uno o más actores, de uno o más narradores. El texto de Marguerite Duras intitulado Sublime forcément sublime Christine V. involucra, por su contenido y su contexto, varias versiones que contrastan y se interrogan entre sí. La escritora se posiciona de tal manera que, a través de recursos propios del oficio literario, desentraña una verdad que puede no ajustarse a la realidad o al saber, pero que nos enfrenta a los límites de lo pulsional y lo ominoso.

  9. Formulation and evaluation of fast dissolving tablets of cinnarizine using superdisintegrant blends and subliming material

    Directory of Open Access Journals (Sweden)

    Biswajit Basu

    2011-01-01

    Full Text Available The aim of this investigation was to develop fast dissolving tablet of cinnarizine. A combination of super disintegrants, i.e., sodium starch glycolate (SSG and crosscarmellose sodium (CCS were used along with camphor as a subliming material. An optimized concentration of camphor was added to aid the porosity of the tablet. A 3 2 full factorial design was applied to investigate the combined effect of two formulation variables: Amount of SSG and CCS. Infrared (IR spectroscopy was performed to identify the physicochemical interaction between drug and polymer. IR spectroscopy showed that there is no interaction of drug with polymer. In the present study, direct compression was used to prepare the tablets. The powder mixtures were compressed into tablet using flat face multi punch tablet machine. Camphor was sublimed from the tablet by exposing the tablet to vacuum drier at 60°C for 12 hours. All the formulations were evaluated for their characteristics such as average weight, hardness, wetting time, friability, content uniformity, dispersion time (DT, and dissolution rate. An optimized tablet formulation (F 9 was found to have good hardness of 3.30 ± 0.10 kg/cm 2 , wetting time of 42.33 ± 4.04 seconds, DT of 34.67 ± 1.53 seconds, and cumulative drug release of not less than 99% in 16 minutes.

  10. Pyrolytic graphite gauge for measuring heat flux

    Science.gov (United States)

    Bunker, Robert C. (Inventor); Ewing, Mark E. (Inventor); Shipley, John L. (Inventor)

    2002-01-01

    A gauge for measuring heat flux, especially heat flux encountered in a high temperature environment, is provided. The gauge includes at least one thermocouple and an anisotropic pyrolytic graphite body that covers at least part of, and optionally encases the thermocouple. Heat flux is incident on the anisotropic pyrolytic graphite body by arranging the gauge so that the gauge surface on which convective and radiative fluxes are incident is perpendicular to the basal planes of the pyrolytic graphite. The conductivity of the pyrolytic graphite permits energy, transferred into the pyrolytic graphite body in the form of heat flux on the incident (or facing) surface, to be quickly distributed through the entire pyrolytic graphite body, resulting in small substantially instantaneous temperature gradients. Temperature changes to the body can thereby be measured by the thermocouple, and reduced to quantify the heat flux incident to the body.

  11. Attenuation of thermal neutron through graphite

    International Nuclear Information System (INIS)

    Adib, M.; Ismaail, H.; Fathaallah, M.; Abbas, Y.; Habib, N.; Wahba, M.

    2004-01-01

    Calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of graphite temperature and crystalline from for neutron energies from 1 me V< E<10 eV were carried out. Computer programs have been developed which allow calculation for the graphite hexagonal closed-pack structure in its polycrystalline form and pyrolytic one. I The calculated total cross-section for polycrystalline graphite were compared with the experimental values. An overall agreement is indicated between the calculated values and experimental ones. Agreement was also obtained for neutron cross-section measured for oriented pyrolytic graphite at room and liquid nitrogen temperatures. A feasibility study for use of graphite in powdered form as a cold neutron filter is details. The calculated attenuation of thermal neutrons through large mosaic pyrolytic graphite show that such crystals can be used effectively as second order filter of thermal neutron beams and that cooling improve their effectiveness

  12. Uranium Oxide Aerosol Transport in Porous Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, Jeremy; Gerlach, David C.; Scheele, Randall D.; Stewart, Mark L.; Reid, Bruce D.; Gauglitz, Phillip A.; Bagaasen, Larry M.; Brown, Charles C.; Iovin, Cristian; Delegard, Calvin H.; Zelenyuk, Alla; Buck, Edgar C.; Riley, Brian J.; Burns, Carolyn A.

    2012-01-23

    The objective of this paper is to investigate the transport of uranium oxide particles that may be present in carbon dioxide (CO2) gas coolant, into the graphite blocks of gas-cooled, graphite moderated reactors. The transport of uranium oxide in the coolant system, and subsequent deposition of this material in the graphite, of such reactors is of interest because it has the potential to influence the application of the Graphite Isotope Ratio Method (GIRM). The GIRM is a technology that has been developed to validate the declared operation of graphite moderated reactors. GIRM exploits isotopic ratio changes that occur in the impurity elements present in the graphite to infer cumulative exposure and hence the reactor’s lifetime cumulative plutonium production. Reference Gesh, et. al., for a more complete discussion on the GIRM technology.

  13. Thermal cyclic oxidation behavior of the developed compositionally gradient graphite material of SiC/C in air environment

    International Nuclear Information System (INIS)

    Nakano, Junichi; Fujii, Kimio; Shindo, Masami

    1993-08-01

    For the developed compositionally gradient graphite material composed of surface SiC coating layer, middle SiC/C layer and graphite matrix, the thermal cyclic oxidation test was performed together with two kinds of the SiC coated graphite materials in air environment. It was made clear that the developed material exhibited high performance under severe thermal cyclic condition independent of the morphology of middle SiC/C layers and had the longer time or the more cycle margins from crack initiation to failure for surface SiC coating layer compared with the SiC coated graphite materials. (author)

  14. Dynamics of graphite flake on a liquid

    Science.gov (United States)

    Miura, K.; Tsuda, D.; Kaneta, Y.; Harada, R.; Ishikawa, M.; Sasaki, N.

    2006-11-01

    One-directional motion, where graphite flakes are driven by a nanotip on an octamethylcyclotetrasiloxane (OMCTS) liquid surface, is presented. A transition from quasiperiodic to chaotic motions occurs in the dynamics of a graphite flake when its velocity is increased. The dynamics of graphite flakes pulled by the nanotip on an OMCTS liquid surface can be treated as that of a nanobody on a liquid.

  15. Sealing nuclear graphite with pyrolytic carbon

    International Nuclear Information System (INIS)

    Feng, Shanglei; Xu, Li; Li, Li; Bai, Shuo; Yang, Xinmei; Zhou, Xingtai

    2013-01-01

    Pyrolytic carbon (PyC) coatings were deposited on IG-110 nuclear graphite by thermal decomposition of methane at ∼1830 °C. The PyC coatings are anisotropic and airtight enough to protect IG-110 nuclear graphite against the permeation of molten fluoride salts and the diffusion of gases. The investigations indicate that the sealing nuclear graphite with PyC coating is a promising method for its application in Molten Salt Reactor (MSR)

  16. Development, installation, and initial operation of DIII-D graphite armor tiles

    International Nuclear Information System (INIS)

    Anderson, P.M.; Baxi, C.B.; Reis, E.E.; Smith, J.P.; Smith, P.D.

    1988-04-01

    An upgrade of the DIII-D vacuum vessel protection system has been completed. The ceiling, floor, and inner wall have been armored to enable operation of CIT-relevant doublenull diverted plasmas and to enable the use of the inner wall as a limiting surface. The all- graphite tiles replace the earlier partial coverage armor configuration which consisted of a combination of Inconel tiles and graphite brazed to Inconel tiles. A new all-graphite design concept was chosen for cost and reliability reasons. The 10 minute duration between plasma discharges required the tiles to be cooled by conduction to the water-cooled vessel wall. Using two and three- dimensional analyses, the tile design was optimized to minimize thermal stresses with uniform thermal loading on the plasma-facing surface. Minimizing the stresses around the tile hold-down feature and eliminating stress concentrators were emphasized in the design. The design of the tile fastener system resulted in sufficient hold-down forces for good thermal conductance to the vessel and for securing the tile against eddy current forces. The tiles are made of graphite, and a program to select a suitable grade of graphite was undertaken. Initially, graphites were compared based on published technical data. Graphite samples were then tested for thermal shock capacity in an electron beam test facility at the Sandia National Laboratory (SNLA) in Albuquerque, New Mexico, USA. 4 refs., 6 figs

  17. Evaluation of high temperature brazes for graphite first wall protection elements

    International Nuclear Information System (INIS)

    Smid, I.; Koizlik, K.; Linke, J.; Nickel, H.; Wallura, E.; Kny, E.

    1989-01-01

    Four different high temperature brazed with melting points from 800 to 1865degC have been used to braze a commercial reactor grade graphite to TZM substrates. Those brazes were Zr, 90Ni 10Ti, 99Cu 10Ti and 70Ag 27Cu 3Ti (wt %). The resulting composite tiles of 80 x 80 mm 2 with a graphite thickness of 10 mm brazed on a 8 mm TZM substrate have been tested in electron beam experiments for their thermal fatigue properties. The parameters of the electron beam testing were chosen to match NET design specificatios for normal operation and 'slow' peak energy deposition. The resulting damages and microstructural changes on the graphite and the brazes are discussed. Additional information is supplied on tensile test and thermal conductivity data of brazed composites. These measurements confirm that thermal contact between TZM-substrate and graphite is improved by brazing. (author). 6 refs.; 5 figs.; 2 tabs

  18. Evaluation of high temperature brazes for graphite first wall protection elements

    International Nuclear Information System (INIS)

    Smid, I.; Koizlik, K.; Linke, J.; Nickel, H.; Wallura, E.; Kny, E.

    1995-01-01

    Four different high temperature brazes with melting points from 800 to 1865 degree C have been used to braze a commercial reactor grade graphite to TZM substrates. Those brazes were Zr, 90Ni 10Ti, 90Cu 10Ti and 70Ag 27Cu 3Ti (wt %). The resulting composite tiles of 80 x 80 mm 2 with a graphite thickness of 10 mm brazed on a 3 mm TZM substrate have been tested in electron beam experiments for their thermal fatigue properties. The parameters of the electron beam testing were chosen to match NET design specifications for normal operation and 'slow' peak energy deposition. The resulting damages and microstructural changes on the graphite and the brazes are discussed. Additional information is supplied on tensile test and thermal conductivity data of brazed composites. These measurements confirm that thermal contact between TZM-substrate and graphite is improved by brazing. (author)

  19. Enthalpies of fusion and enthalpies of solvation of aromatic hydrocarbons derivatives: Estimation of sublimation enthalpies at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, Boris N., E-mail: boris.solomonov@kpfu.ru; Nagrimanov, Ruslan N.; Varfolomeev, Mikhail A.; Buzyurov, Aleksey V.; Mukhametzyanov, Timur A.

    2016-03-20

    Graphical abstract: - Highlights: • Solution enthalpies of aromatic hydrocarbons derivatives (ArHD) were measured at 298.15 K. • Solution enthalpies of ArHD in benzene at 298.15 K are equal to their fusion enthalpy at melting point. • Sublimation enthalpies of 80 ArHD were calculated as a sum of fusion and solvation enthalpies. • Obtained sublimation enthalpies are in good agreement with the recommended literature data. - Abstract: Enthalpy of sublimation of solid compound can be found using the values of solution enthalpy and solvation enthalpy in any solvent. In this work enthalpies of solution at infinite dilution of a number of aromatic hydrocarbons derivatives in benzene were measured at 298.15 K. Comparison between experimental and literature solution enthalpies in benzene at 298.15 K and fusion enthalpies at melting temperature of aromatic hydrocarbon derivatives showed, that these values are approximately equal. Thereby, fusion enthalpies at melting temperature can be used instead of their solution enthalpies in benzene at 298.15 K for calculation of sublimation enthalpies at 298.15 K. Solvation enthalpies in benzene at 298.15 K required for this procedure were calculated using group additivity scheme. The sublimation enthalpies of 80 aromatic hydrocarbons derivatives at 298.15 K were evaluated as a difference between fusion enthalpies at melting temperature and solvation enthalpies in benzene at 298.15 K. Obtained in this work values of sublimation enthalpy at 298.15 K for studied compounds were in a good agreement with available literature data.

  20. Nanostructured carbon films with oriented graphitic planes

    International Nuclear Information System (INIS)

    Teo, E. H. T.; Kalish, R.; Kulik, J.; Kauffmann, Y.; Lifshitz, Y.

    2011-01-01

    Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 deg. C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphitic planes under different conditions.

  1. Production of nuclear graphite in France

    International Nuclear Information System (INIS)

    Legendre, P.; Mondet, L.; Arragon, Ph.; Cornuault, P.; Gueron, J.; Hering, H.

    1955-01-01

    The graphite intended for the construction of the reactors is obtained by the usual process: confection of a cake from coke of oil and tar, cooked (in a electric oven) then the product of cook is graphitized, also by electric heating. The use of the air transportation and the control of conditions cooking and graphitization have permitted to increase the nuclear graphite production as well as to better control their physical and mechanical properties and to reduce to the minimum the unwanted stains. (M.B.) [fr

  2. AC induction field heating of graphite foam

    Science.gov (United States)

    Klett, James W.; Rios, Orlando; Kisner, Roger

    2017-08-22

    A magneto-energy apparatus includes an electromagnetic field source for generating a time-varying electromagnetic field. A graphite foam conductor is disposed within the electromagnetic field. The graphite foam when exposed to the time-varying electromagnetic field conducts an induced electric current, the electric current heating the graphite foam. An energy conversion device utilizes heat energy from the heated graphite foam to perform a heat energy consuming function. A device for heating a fluid and a method of converting energy are also disclosed.

  3. Nuclear graphite for high temperature reactors

    International Nuclear Information System (INIS)

    Marsden, B.J.

    2001-01-01

    The cores and reflectors in modern High Temperature Gas Cooled Reactors (HTRs) are constructed from graphite components. There are two main designs; the Pebble Bed design and the Prism design. In both of these designs the graphite not only acts as a moderator, but is also a major structural component that may provide channels for the fuel and coolant gas, channels for control and safety shut off devices and provide thermal and neutron shielding. In addition, graphite components may act as a heat sink or conduction path during reactor trips and transients. During reactor operation, many of the graphite component physical properties are significantly changed by irradiation. These changes lead to the generation of significant internal shrinkage stresses and thermal shut down stresses that could lead to component failure. In addition, if the graphite is irradiated to a very high irradiation dose, irradiation swelling can lead to a rapid reduction in modulus and strength, making the component friable.The irradiation behaviour of graphite is strongly dependent on its virgin microstructure, which is determined by the manufacturing route. Nevertheless, there are available, irradiation data on many obsolete graphites of known microstructures. There is also a well-developed physical understanding of the process of irradiation damage in graphite. This paper proposes a specification for graphite suitable for modern HTRs. (author)

  4. Structural analysis of polycrystalline (graphitized) materials

    International Nuclear Information System (INIS)

    Efremenko, M.M.; Kravchik, A.E.; Osmakov, A.S.

    1993-01-01

    Specific features of the structure of polycrystal carbon materials (CM), characterized by high enough degree of structural perfection and different genesis are analyzed. From the viewpoint of fine and supercrystallite structure analysis of the most characteristic groups of graphitized CM: artificial graphites, and natural graphites, as well, has been carried out. It is ascertained that in paracrystal CM a monolayer of hexagonally-bound carbon atoms is the basic element of the structure, and in graphitized CM - a microlayer. The importance of the evaluation of the degree of three-dimensional ordering of the microlayer is shown

  5. Low temperature vapor phase digestion of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Robert A.

    2017-04-18

    A method for digestion and gasification of graphite for removal from an underlying surface is described. The method can be utilized to remove graphite remnants of a formation process from the formed metal piece in a cleaning process. The method can be particularly beneficial in cleaning castings formed with graphite molding materials. The method can utilize vaporous nitric acid (HNO.sub.3) or vaporous HNO.sub.3 with air/oxygen to digest the graphite at conditions that can avoid damage to the underlying surface.

  6. The Fracture Toughness of Nuclear Graphites Grades

    Energy Technology Data Exchange (ETDEWEB)

    Burchell, Timothy D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Erdman, III, Donald L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lowden, Rick R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hunter, James A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hannel, Cara C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-04-01

    New measurements of graphite mode I critical stress intensity factor, KIc (commonly referred to as the fracture toughness) and the mode II critical shear stress intensity, KIIc, are reported and compared with prior data for KIc and KIIc. The new data are for graphite grades PCEA, IG-110 and 2114. Variations of KIc and acoustic emission (AE) data with graphite texture are reported and discussed. The Codes and Standards applications of fracture toughness, KIc, data are also discussed. A specified minimum value for nuclear graphite KIc is recommended.

  7. Electrolysis of acidic sodium chloride solution with a graphite anode. I. Graphite electrode

    NARCIS (Netherlands)

    Janssen, L.J.J.; Hoogland, J.G.

    1969-01-01

    A graphite anode evolving Cl from a chloride soln. is slowly oxidized to CO and CO2. This oxidn. causes a change in the characteristics of the electrode in aging, comprising a change of the nature of the graphite surface and an increase of the surface area. It appears that a new graphite electrode

  8. Chemical analysis of high purity graphite

    International Nuclear Information System (INIS)

    1993-03-01

    The Sub-Committee on Chemical Analysis of Graphite was organized in April 1989, under the Committee on Chemical Analysis of Nuclear Fuels and Reactor Materials, JAERI. The Sub-Committee carried out collaborative analyses among eleven participating laboratories for the certification of the Certified Reference Materials (CRMs), JAERI-G5 and G6, after developing and evaluating analytical methods during the period of September 1989 to March 1992. The certified values were given for ash, boron and silicon in the CRM based on the collaborative analysis. The values for ten elements (Al, Ca, Cr, Fe, Mg, Mo, Ni, Sr, Ti, V) were not certified, but given for information. Preparation, homogeneity testing and chemical analyses for certification of reference materials were described in this paper. (author) 52 refs

  9. Graphite stack corrosion of BUGEY-1 reactor (synthesis)

    International Nuclear Information System (INIS)

    Petit, A.; Brie, M.

    1996-01-01

    The definitive shutdown date for the BUGEY-1 reactor was May 27th, 1994, after 12.18 full power equivalent years and this document briefly describes some of the feedback of experience from operation of this reactor. The radiolytic corrosion of graphite stack is the major problem for BUGEY-1 reactor, despite the inhibition of the reaction by small quantities of CH 4 added to the coolant gas. The mechanical behaviour of the pile is predicted using the ''INCA'' code (stress calculation), which uses the results of graphite weight loss variation determined using the ''USURE'' code. The weight loss of graphite is determined by annually taking core samples from the channel walls. The results of the last test programme undertaken after the definitive shutdown of BUGEY-1 have enabled an experimental graph to be established showing the evolution of the compression resistance (perpendicular and parallel direction to the extrusion axis) as a function of the weight loss. The numerous analyses, made on the samples carried out in the most sensitive regions, have allowed to verify that no brutal degradation of the mechanical properties of graphite happens for the high value of weight loss up to 40% (maximum weight loss reached locally). (author). 10 refs, 3 figs, 4 tabs

  10. Comparison of Oxidation Characteristics of Selected Nuclear Graphite Grades

    International Nuclear Information System (INIS)

    Chi, Se Hwan; Kim, Gen Chan

    2010-02-01

    The oxidation behavior of some selected nuclear graphite grades (i.e., IG-110, IG-430, NBG-18, NBG-25) were compared in view of their filler coke type and the physical property of the grades. Oxidation rates were determined at six temperatures between 600 ∼ 960 .deg. C in air by using a three-zone vertical tube furnace at a 10 L/min air flow rate. The specimens were a cylinder with a 25.4 mm diameter and a 25.4 mm length. Results showed that, even though the four examined nuclear graphite grades showed a highly temperature-sensitive oxidation behavior through out the test temperature range of 600 ∼ 950 .deg. C, the differences between the grades were not significant. The oxidation rates determined for a 5∼10 % weight loss at the six temperatures were nearly the same except for 702 and 808 .deg. C, where the pitch coke graphites showed an apparent decrease in their oxidation rate, more so than the petroleum coke graphites. These effects of the coke type reduced or nearly disappeared with an increasing temperature. The average activation energy determined for 608 ∼ 808 .deg. C was 161.5 ± 7.3 kJ/mol, showing that the dominant oxidation reaction occurred by a chemical control

  11. A microstructurally based fracture model for nuclear graphite

    International Nuclear Information System (INIS)

    Burchell, T.D.

    1991-01-01

    This paper reports the physical basis of, and assumptions behind, a fracture model for nuclear graphites. Microstructurally related inputs, such as filler particle size, filler particle fracture toughness (K Ic ), density, pore size distribution, number of pores and specimen geometry (size and volume), are utilized in the model. The model has been applied to two graphites, Great Lakes Carbon Corporation grade H-451 and Toyo Tanso grade IG-110. For each graphite, the predicted tensile failure probabilities are compared with experimental data generated using ASTM Standard C-749 tensile test specimens. The predicted failure probabilities are in close agreement with the experimental data, particularly in the case of the H-451. The model is also shown to qualitatively predict the influence on the failure probabilities of changes in filler particle size, density, pore size, pore size distribution, number of pores and specimen geometry (stressed volume). The good performance is attributed to the sound physical basis of the model, which recognizes the dominant role of porosity in controlling crack initiation and propagation during graphite fracture. 8 refs., 12 figs., 1 tab

  12. AMS-C14 analysis of graphite obtained with an Automated Graphitization Equipment (AGE III) from aerosol collected on quartz filters

    Energy Technology Data Exchange (ETDEWEB)

    Solís, C.; Chávez, E.; Ortiz, M.E.; Andrade, E. [Instituto de Física, Universidad Nacional Autónoma de México, 04510 México D.F. (Mexico); Ortíz, E. [Universidad Autónoma Metropolitana, Unidad Azcapotzalco, México D.F. (Mexico); Szidat, S. [Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern (Switzerland); Paul Scherrer Institut (PSI), CH-5232 Villigen (Switzerland); Wacker, L. [Laboratory of Ion Physics, ETH, Honggerberg, Zurich (Switzerland)

    2015-10-15

    AMS-{sup 14}C applications often require the analysis of small samples. Such is the case of atmospheric aerosols where frequently only a small amount of sample is available. The ion beam physics group at the ETH, Zurich, has designed an Automated Graphitization Equipment (AGE III) for routine graphite production for AMS analysis from organic samples of approximately 1 mg. In this study, we explore the potential use of the AGE III for graphitization of particulate carbon collected in quartz filters. In order to test the methodology, samples of reference materials and blanks with different sizes were prepared in the AGE III and the graphite was analyzed in a MICADAS AMS (ETH) system. The graphite samples prepared in the AGE III showed recovery yields higher than 80% and reproducible {sup 14}C values for masses ranging from 50 to 300 μg. Also, reproducible radiocarbon values were obtained for aerosol filters of small sizes that had been graphitized in the AGE III. As a study case, the tested methodology was applied to PM{sub 10} samples collected in two urban cities in Mexico in order to compare the source apportionment of biomass and fossil fuel combustion. The obtained {sup 14}C data showed that carbonaceous aerosols from Mexico City have much lower biogenic signature than the smaller city of Cuernavaca.

  13. Changes in the physical and mechanical properties of graphite on irradiation in ditolylmethane

    International Nuclear Information System (INIS)

    Gavrilin, A.I.; Lebedev, I.G.; Sudakova, N.V.; Rizvanov, V.K.

    1987-01-01

    Results are presented from the irradiation and mechanical and structural testing of four grades of graphite - GMZ, VPG, MPG-6, and PG-50 - for use as moderator materials in organic cooled and graphite moderated reactors. Irradiation was carried out in the ARBUS-AST-1 reactor. Photomicrography was used to determine pore structure and ultimate strength in bending and compression was determined mechanically. Irradiation was found to increase the strength of GMZ, PMG-6, and PG-50 considerably, due to the healing of microdefects as a result of the pores filling with radiolysis products from the coolant, ditolylmethane. Conversely, VPG graphite, which has closed porosity, lost strength on irradiation

  14. Structural integrity of graphite core support structures of HTTR

    International Nuclear Information System (INIS)

    Inagaki, Yoshiyuki; Iyoku, Tatsuo; Toyota, Junji; Sato, Sadao; Shiozawa, Shusaku

    1990-02-01

    The graphite core support structures (GCSSs) of the HTTR (High Temperature Engineering Test Reactor) are an arrangement of graphite blocks and posts that support the core and provide a lower plenum and a hot-leg path for the primary coolant. The GCSSs are designed not to be replaced by new items during plant life time (about twenty years). To maintain structural integrity of the GCSSs, conservative design has been made sufficiently on the basis of structural tests. The present study confirmed that reactor safety was still maintained even if failure and destruction of the GCSSs is supposed to occur. The GCSSs are fabricated under strict quality control and the observation and surveillance programs are planed to examine the structual integrity of the GCSSs during an operation. This paper describes the concept of design and quality control and summarizes structural tests, observation and surveillance programs. (author)

  15. Verification and validation of the THYTAN code for the graphite oxidation analysis in the HTGR systems

    International Nuclear Information System (INIS)

    Shimazaki, Yosuke; Isaka, Kazuyoshi; Nomoto, Yasunobu; Seki, Tomokazu; Ohashi, Hirofumi

    2014-12-01

    The analytical models for the evaluation of graphite oxidation were implemented into the THYTAN code, which employs the mass balance and a node-link computational scheme to evaluate tritium behavior in the High Temperature Gas-cooled Reactor (HTGR) systems for hydrogen production, to analyze the graphite oxidation during the air or water ingress accidents in the HTGR systems. This report describes the analytical models of the THYTAN code in terms of the graphite oxidation analysis and its verification and validation (V and V) results. Mass transfer from the gas mixture in the coolant channel to the graphite surface, diffusion in the graphite, graphite oxidation by air or water, chemical reaction and release from the primary circuit to the containment vessel by a safety valve were modeled to calculate the mass balance in the graphite and the gas mixture in the coolant channel. The computed solutions using the THYTAN code for simple questions were compared to the analytical results by a hand calculation to verify the algorithms for each implemented analytical model. A representation of the graphite oxidation experimental was analyzed using the THYTAN code, and the results were compared to the experimental data and the computed solutions using the GRACE code, which was used for the safety analysis of the High Temperature Engineering Test Reactor (HTTR), in regard to corrosion depth of graphite and oxygen concentration at the outlet of the test section to validate the analytical models of the THYTAN code. The comparison of THYTAN code results with the analytical solutions, experimental data and the GRACE code results showed the good agreement. (author)

  16. Hydrogen storage in graphitic nanofibres

    OpenAIRE

    McCaldin, Simon Roger

    2007-01-01

    There is huge need to develop an alternative to hydrocarbons fuel, which does not produce CO2 or contribute to global warming - 'the hydrogen economy' is such an alternative, however the storage of hydrogen is the key technical barrier that must be overcome. The potential of graphitic nanofibres (GNFs) to be used as materials to allow the solid-state storage of hydrogen has thus been investigated. This has been conducted with a view to further developing the understanding of the mechanism(s) ...

  17. Mixed graphite cast iron for automotive exhaust component applications

    OpenAIRE

    De-lin Li

    2017-01-01

    Both spheroidal graphite iron and compacted graphite iron are used in the automotive industry. A recently proposed mixed graphite iron exhibits a microstructure between the conventional spheroidal graphite iron and compacted graphite iron. Evaluation results clearly indicate the suitability and benefits of mixed graphite iron for exhaust component applications with respect to casting, machining, mechanical, thermophysical, oxidation, and thermal fatigue properties. A new ASTM standard speci...

  18. Nuclear graphite waste management. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    2001-05-01

    The purpose of the seminar was to bring together the specialists dealing with various aspects of radioactive graphite waste management to exchange and review information on the decommissioning, characterisation, processing and disposal of irradiated graphite from reactor cores and other graphite waste associated with reactor operation. The seminar covered radioactive graphite characterisation, the effect of irradiation on graphite components, Wigner energy, radioactive graphite waste treatment, conditioning, interim storage and long term disposal options. Individual papers presented at the seminar were indexed separately

  19. Oxidation of PCEA nuclear graphite by low water concentrations in helium

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I., E-mail: ContescuCI@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6087 (United States); Mee, Robert W. [Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN 37996-0525 (United States); Wang, Peng [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6087 (United States); Romanova, Anna V.; Burchell, Timothy D. [Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN 37996-0525 (United States)

    2014-10-15

    Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction (i.e. slow, continuous, and persistent) of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors’ knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam (Velasquez, Hightower, Burnette, 1978). Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades that are being considered for use in gas-cooled reactors. The Langmuir–Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800–1100 °C), and partial pressures of water (15–850 Pa) and hydrogen (30–150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity between the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another.

  20. Draft of standard for graphite core components in high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Shibata, Taiju; Sawa, Kazuhiro; Eto, Motokuni; Kunimoto, Eiji; Shiozawa, Shusaku; Oku, Tatsuo; Maruyama, Tadashi

    2010-01-01

    For the design of the graphite components in the High Temperature Engineering Test Reactor (HTTR), the graphite structural design code for the HTTR etc. were applied. However, general standard systems for the High Temperature Gas-cooled Reactor (HTGR) have not been established yet. The authors had studied on the technical issues which is necessary for the establishment of a general standard system for the graphite components in the HTGR. The results of the study were documented and discussed at a 'Special committee on research on preparation for codes for graphite components in HTGR' at Atomic Energy Society of Japan (AESJ). As a result, 'Draft of Standard for Graphite Core Components in High Temperature Gas-cooled Reactor.' was established. In the draft standard, the graphite components are classified three categories (A, B and C) in the standpoints of safety functions and possibility of replacement. For the components in the each class, design standard, material and product standards, and in-service inspection and maintenance standard are determined. As an appendix of the design standard, the graphical expressions of material property data of 1G-110 graphite as a function of fast neutron fluence are expressed. The graphical expressions were determined through the interpolation and extrapolation of the irradiated data. (author)

  1. Analysis of Wigner energy release process in graphite stack of shut-down uranium-graphite reactor

    OpenAIRE

    Bespala, E. V.; Pavliuk, A. O.; Kotlyarevskiy, S. G.

    2015-01-01

    Data, which finding during thermal differential analysis of sampled irradiated graphite are presented. Results of computational modeling of Winger energy release process from irradiated graphite staking are demonstrated. It's shown, that spontaneous combustion of graphite possible only in adiabatic case.

  2. Estimation of Graphite Dust Production in ITER TBM

    International Nuclear Information System (INIS)

    Kang, Ji Ho; Kim, Eung Seon

    2013-01-01

    This scheme uses simple equations and the calculation time is much less than others. However, the contact equation requires a specially tuned material properties and instability of system matrix were reported. Second, only a couple of pebbles were modeled using FEM(Finite Element Method) and appropriate boundary and loading conditions are imposed. This scheme gives a detailed information of stress distribution of the pebbles and the stability of calculation is well established. However, the calculation cost is fairly high and only a few pebble can be analyzed in detail at a time with specifically assigned contact conditions. In this study, a prediction model of graphite dust production in ITER(International Thermonuclear Experimental Reactor) TBM(Test Blanket Module) using FEM was introduced and the amount of dust production for an operation cycle was estimated. In this study, graphite dust generation in the reflector zone of ITER TBM was estimated using FE analysis. A unit-cell model was defined to simulate normal contact forces and slip distances on contact points between the center pebble and the surrounding pebbles. The dust production was calculated using Archard equation. The simulation was repeated with different friction coefficient of graphite material to investigate the effect of friction on the dust production. The calculation result showed that the amount of dust production was 2.22∼3.67e-4 g/m 3 which was almost linearly proportional to the friction coefficient of graphite material. The amount of graphite dust production was considered too much small for a dust explosion

  3. Measurement of the enthalpies of vaporization and sublimation of solids aromatic hydrocarbons by differential scanning calorimetry

    International Nuclear Information System (INIS)

    Rojas, Aaron; Orozco, Eulogio

    2003-01-01

    An experimental procedure is proposed for direct measurement of the heat involved in the vaporization of a solid organic compound above its normal melting temperature. This technique consists on the fusion of a solid aromatic hydrocarbon, which is then vaporized by a sudden decrease of the pressure. The direct register of heat flow as function of time by differential scanning calorimetry allows the quantifying of the enthalpy of vaporization of compounds such as phenanthrene, β-naphthol, pyrene, and anthracene. Enthalpies of vaporization were measured in an isothermal mode over a range of temperatures from 10 to 20 K above the melting temperatures of each compound, while enthalpies of fusion were determined from separate experiments performed in a scanning mode. Enthalpies of sublimation are computed from results of fusion and vaporization, and then compared with results from the literature, which currently are obtained by calorimetric or indirect techniques

  4. Lepanto, before and after: Between the Republic and the Sublime Porte

    Directory of Open Access Journals (Sweden)

    Özlem KUMRUlAR

    2014-12-01

    Full Text Available The loss of Cyprus to the ottoman Turks, hand in hand with the Battle of Lepanto was the major reason of a period of frozen politics and caused the breaking of the traditional peace between Venice and Constantinople. Yet there is a notable difference between the historical and political Conseptualization of these two major episodes. The ottoman state didn’t interpret this catastrophe as the Republic did. As, it could be seen from the bilateral diplomacy carried out by both states, neither the loss of Cyprus, nor the myth-creating Lepanto could change the classical oriental policy of the Serenissima. The case was not different for the Sublime Porte. The aim of this paper is to analyse the post-war politics of these two states and the noteable change in the political polarization in Europe in the milieu of the ottoman-Hapsburg rivalry.

  5. Concentration of noble metals by sublimation during the analysis of massive samples

    International Nuclear Information System (INIS)

    Chuburkov, Yu.T.; Zhujkov, B.L.; Gehrbish, Sh.; Al'pert, L.K.; Chan Zuj Ty

    1990-01-01

    The possibility of concentrating noble metals from terrestrial samples of various composition by chemical sublimation in an air stream at a temperature of 1000-1200 deg C was examined. It was found that the chemical yields of Au, Pt, Ir, Ru, Os and Re for all the samples increased by introducing solid additives of FeCl 2 , TiO 2 and Nb 2 O 5 . The concentration technique provides the possibility of determining some noble metals in massive samples (up to 50 g) with widely ranging element contents. By using gamma and neutron activation on a microtron, the detection limits of 3x10 -2 ppm for Pt and Ir and 4x10 -3 ppm for Au were achieved. In the case of X-ray fluorescence analysis, the detection limit for these elements was 0.4 ppm

  6. Formation of the molecular crystal structure during the vacuum sublimation of paracetamol

    Science.gov (United States)

    Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.

    2015-04-01

    The results from structural and thermal studies on the formation of molecular crystals during the vacuum sublimation of paracetamol from its vapor phase are given. It is established that the vapor-crystal phase transition proceeds in a complicated way as the superposition of two phase transitions: a first-order phase transition with a change in density, and a second-order phase transition with a change in ordering. It is shown that the latter is a smeared phase transition that proceeds with the formation of a pretransitional phase that is irreversibly dissipated during phase transformation, leading to the formation of crystals of the rhombic syngony. Data from differential scanning calorimetry and X-ray diffraction analysis are presented along with microphotographs.

  7. Paths of the Sublime: Alain de Botton’s The Art of Travel

    Directory of Open Access Journals (Sweden)

    M.C.C. Mendes

    2015-05-01

    Full Text Available Bearing in mind the central place of literary, academic, and religious tourism in Cultural Studies and in Alain de Botton’s The Art of Travel (2002, the paper seeks: 1 to identify some remarkable travels of famous writers – the British Wordsworth; the French Karl-Joris Huysmans, Gustave Flaubert, and Charles Baudelaire; 2 to show that in the analysis of such authors’ itineraries (from Europe to the East, there is a search for cultural roots, a mapping of spaces and people, and a deconstruction of labels often related to the Other; 3 to point out that the tourist is also a storyteller, a protagonist, and a creator of fictional worlds; 4 to bring together literary tourism and artistic tourism, through the identification of allusions to other cultural events (painting, music, and architecture; 5 to characterize tourism as a literary and aesthetic experience of the Sublime.

  8. Characteristics of Vacuum Freeze Drying with Utilization of Internal Cooling and Condenser Waste Heat for Sublimation

    Directory of Open Access Journals (Sweden)

    Muhammad Alhamid

    2013-09-01

    Full Text Available Vacuum freeze drying is an excellent drying method, but it is very energy-intensive because a relatively long drying time is required. This research investigates the utilization of condenser waste heat for sublimation as a way of accelerating the drying rate. In addition, it also investigates the effect of internal cooling combined with vacuum cooling in the pressure reduction process. Jelly fish tentacles were used as the specimen, with different configurations for condenser heat waste and internal cooling valve opening. The results show that heating with condenser heat waste can accelerate the drying rate up to 0.0035 kg/m2.s. In addition, pre-freezing by internal cooling prevents evaporation until the mass of the specimen is 0.47 g and promotes transition of the specimen into the solid phase.

  9. Synthesis of gallium nitride and related oxides via ammonobasic reactive sublimation (ARS)

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Hernández, Luis Alberto; Aguilar-Hernández, Jorge R.; Mejía-García, Concepción; Cruz-Gandarilla, Francisco; Contreras-Puente, Gerardo [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Ciudad de México (Mexico); Moure-Flores, Francisco de [Facultad de Química, Materiales-Energía, Universidad Autónoma de Querétaro (Mexico); Melo-Pereira, Osvaldo de, E-mail: schwarzerengelxv@hotmail.com [Facultad de Física, Universidad de La Habana, La Habana (Cuba)

    2017-11-15

    Ammonobasic reactive sublimation (ARS) is proposed as a novel method to synthesize GaN and related oxides. Results indicate that GaN growth occurs by a nitriding process of Ga and related oxides, establishing a direct dependence on NH{sub 4} OH amount added as a primary chemical reactive. The samples were grown on p-type Si (111) substrates inside a tube furnace, employing GaN powder and NH{sub 4} OH. The characterizations of the samples were carried out by XRD, SEM, EDS and PL techniques, revealing the influence of NH{sub 4} OH on the improvement of GaN synthesis and the enhancement of its optical and structural properties. (author)

  10. Selective Area Sublimation: A Simple Top-down Route for GaN-Based Nanowire Fabrication.

    Science.gov (United States)

    Damilano, B; Vézian, S; Brault, J; Alloing, B; Massies, J

    2016-03-09

    Post-growth in situ partial SiNx masking of GaN-based epitaxial layers grown in a molecular beam epitaxy reactor is used to get GaN selective area sublimation (SAS) by high temperature annealing. Using this top-down approach, nanowires (NWs) with nanometer scale diameter are obtained from GaN and InxGa1-xN/GaN quantum well epitaxial structures. After GaN regrowth on InxGa1-xN/GaN NWs resulting from SAS, InxGa1-xN quantum disks (QDisks) with nanometer sizes in the three dimensions are formed. Low temperature microphotoluminescence experiments demonstrate QDisk multilines photon emission around 3 eV with individual line widths of 1-2 meV.

  11. The role of defects in fluorescent silicon carbide layers grown by sublimation epitaxy

    DEFF Research Database (Denmark)

    Schimmel, Saskia; Kaiser, Michl; Jokubavicius, Valdas

    Donor-acceptor co-doped silicon carbide layers are promising light converters for novel monolithic all-semiconductor LEDs due to their broad-band donor-acceptor pair luminescence and potentially high internal quantum efficiency. Besides appropriate doping concentrations yielding low radiative...... lifetimes, high nonradiative lifetimes are crucial for efficient light conversion. Despite the excellent crystalline quality that can generally be obtained by sublimation epitaxy according to XRD measurements, the role of defects in f-SiC is not yet well understood. Recent results from room temperature...... photoluminescence, charge carrier lifetime measurements by microwave detected photoconductivity and internal quantum efficiency measurements suggest that the internal quantum efficiency of f-SiC layers is significantly affected by the incorporation of defects during epitaxy. Defect formation seems to be related...

  12. Mixed graphite cast iron for automotive exhaust component applications

    Directory of Open Access Journals (Sweden)

    De-lin Li

    2017-11-01

    Full Text Available Both spheroidal graphite iron and compacted graphite iron are used in the automotive industry. A recently proposed mixed graphite iron exhibits a microstructure between the conventional spheroidal graphite iron and compacted graphite iron. Evaluation results clearly indicate the suitability and benefits of mixed graphite iron for exhaust component applications with respect to casting, machining, mechanical, thermophysical, oxidation, and thermal fatigue properties. A new ASTM standard specification (A1095 has been created for compacted, mixed, and spheroidal graphite silicon-molybdenum iron castings. This paper attempts to outline the latest progress in mixed graphite iron published.

  13. Methodology of characterization of radioactive graphite

    International Nuclear Information System (INIS)

    Pina, G.; Rodriguez, M.; Lara, E.; Magro, E.; Gascon, J. L.; Leganes, J. L.

    2014-01-01

    Since the dismantling of Vandellos I, ENRESA has promoted the precise knowledge of the inventory of irradiated graphite (graphite-i) through establishing methodologies for radiological characterization of the vector of radionuclides of interest and their correlations as the primary means of characterization strategy to establish the safer management of this material in its life cycle. (Author)

  14. Significance of primary irradiation creep in graphite

    CSIR Research Space (South Africa)

    Erasmus, C

    2013-05-01

    Full Text Available Traditionally primary irradiation creep is introduced into graphite analysis by applying the appropriate amount of creep strain to the model at the initial time-step. This is valid for graphite components that are subjected to high fast neutron flux...

  15. Inhibition of oxidation in nuclear graphite

    International Nuclear Information System (INIS)

    Winston, Philip L.; Sterbentz, James W.; Windes, William E.

    2015-01-01

    Graphite is a fundamental material of high-temperature gas-cooled nuclear reactors, providing both structure and neutron moderation. Its high thermal conductivity, chemical inertness, thermal heat capacity, and high thermal structural stability under normal and off-normal conditions contribute to the inherent safety of these reactor designs. One of the primary safety issues for a high-temperature graphite reactor core is the possibility of rapid oxidation of the carbon structure during an off-normal design basis event where an oxidising atmosphere (air ingress) can be introduced to the hot core. Although the current Generation IV high-temperature reactor designs attempt to mitigate any damage caused by a postulated air ingress event, the use of graphite components that inhibit oxidation is a logical step to increase the safety of these reactors. Recent experimental studies of graphite containing between 5.5 and 7 wt% boron carbide (B 4 C) indicate that oxidation is dramatically reduced even at prolonged exposures at temperatures up to 900 deg. C. The proposed addition of B 4 C to graphite components in the nuclear core would necessarily be enriched in B-11 isotope in order to minimise B-10 neutron absorption and graphite swelling. The enriched boron can be added to the graphite during billet fabrication. Experimental oxidation rate results and potential applications for borated graphite in nuclear reactor components will be discussed. (authors)

  16. Metal/graphite - composites in fusion engineering

    International Nuclear Information System (INIS)

    Staffler, R.; Kneringer, G.; Kny, E.; Reheis, N.

    1989-01-01

    Metal/graphite composites have been well known in medical industry for many years. X-ray tubes used in modern radiography, particularly in computerized tomography are equipped with rotating targets able to absorb a maximum of heat in a given time. Modern rotating targets consist of a refractory metal/graphite composite. Today the use of graphite as a plasma facing material is one predominant concept in fusion engineering. Depending on the thermal load, the graphite components have to be directly cooled (i.e. divertor plates) or inertially cooled (i.e. firstwall tiles). In case of direct cooling a metallurgical joining such as high temperature brazing between graphite and a metallic cooling structure shows the most promising results /1/. Inertially cooled graphite tiles have to be joined to a metallic backing plate in order to get a stable attachment to the supporting structure. The main requirements on the metallic partner of a metal/graphite composite used in the first wall area are: high melting point, high thermal strength, high thermal conductivity, low vapor pressure and a thermal expansion matching that of graphite. These properties are typical for the refractory metals such as molybdenum, tungsten and their alloys. 4 refs., 13 figs., 1 tab

  17. Metal/graphite - composites in fusion engineering

    International Nuclear Information System (INIS)

    Staffler, R.; Kneringer, G.; Kny, E.; Reheis, N.

    1995-01-01

    Metal/graphite composites have been well known in medical industry for many years. X-ray tubes used in modern radiography, particulary in computerized tomography are equipped with rotating targets able to absorb a maximum of heat in a given time. Modern rotating targets consist of a refractory metal/graphite composite. Today the use of graphite as a plasma facing material is one predominant concept in fusion engineering. Depending on the thermal load, the graphite components have to be directly cooled (i.e. divertor plates) or inertially cooled (i.e. firstwall tiles). In case of direct cooling a metallurgical joining such as high temperature brazing between graphite and a metalic cooling structure shows the most promising results /1/. Inertially cooled graphite tiles have to be joined to a metallic backing plate in order to get a stable attachment to the supporting structure. The main requirements on the metallic partner of a metal/graphite composite and in the first wall area are: high melting point, high thermal strength, high thermal conductivity, low vapour pressure and a thermal expansion matching that of graphite. These properties are typical for the refractory metals such as molybdenum, tungsten and their alloys. (author)

  18. Tire containing thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2011-01-01

    A tire, tire lining or inner tube, containing a polymer composite, made of at least one rubber and/or at least one elastomer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g.

  19. Effect of graphite target power density on tribological properties of graphite-like carbon films

    Science.gov (United States)

    Dong, Dan; Jiang, Bailing; Li, Hongtao; Du, Yuzhou; Yang, Chao

    2018-05-01

    In order to improve the tribological performance, a series of graphite-like carbon (GLC) films with different graphite target power densities were prepared by magnetron sputtering. The valence bond and microstructure of films were characterized by AFM, TEM, XPS and Raman spectra. The variation of mechanical and tribological properties with graphite target power density was analyzed. The results showed that with the increase of graphite target power density, the deposition rate and the ratio of sp2 bond increased obviously. The hardness firstly increased and then decreased with the increase of graphite target power density, whilst the friction coefficient and the specific wear rate increased slightly after a decrease with the increasing graphite target power density. The friction coefficient and the specific wear rate were the lowest when the graphite target power density was 23.3 W/cm2.

  20. Oxidation parameters of nuclear graphite for HTGR air-ingress

    International Nuclear Information System (INIS)

    Kim, E.S.; No, H.C.

    2004-01-01

    In order to investigate chemical behaviors of the graphite during an air-ingress accident in HTGR, the kinetic tests on nuclear graphite IG-110 were performed in chemical reaction dominant regime. In the present experiment, inlet gas flow rate ranged between 8 and 18 SLPM, graphite temperatures and oxygen mole fraction ranged from 540 to 630degC and from 3 to 30% respectively. The test section was made of a quartz tube having 75 mm diameter and 750 mm length and the test specimen machined to the size of 21 mm diameter and 30 mm length was supported at the center of it by the alumina rod. The 15 kW induction heater was installed around the outside of test section to heat the specimen and its temperature was measured by 2 infrared thermometers. The oxidation rate was calculated from the gas concentration analysis between inlet and outlet using NDIR (non-dispersive infrared) gas analyzer. As a result the activation energy (Ea) and the order of reaction (n) were determined within 95% confidence level and the qualitative characteristics of the two parameters were also widely investigated by experimental and analytical methods. (author)

  1. Hydrogen storage in graphite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Park, C.; Tan, C.D.; Hidalgo, R.; Baker, R.T.K.; Rodriguez, N.M. [Northeastern Univ., Boston, MA (United States). Chemistry Dept.

    1998-08-01

    Graphite nanofibers (GNF) are a type of material that is produced by the decomposition of carbon containing gases over metal catalyst particles at temperatures around 600 C. These molecularly engineered structures consist of graphene sheets perfectly arranged in a parallel, perpendicular or at angle orientation with respect to the fiber axis. The most important feature of the material is that only edges are exposed. Such an arrangement imparts the material with unique properties for gas adsorption because the evenly separated layers constitute the most ordered set of nanopores that can accommodate an adsorbate in the most efficient manner. In addition, the non-rigid pore walls can also expand so as to accommodate hydrogen in a multilayer conformation. Of the many varieties of structures that can be produced the authors have discovered that when gram quantities of a selected number of GNF are exposed to hydrogen at pressures of {approximately} 2,000 psi, they are capable of adsorbing and storing up to 40 wt% of hydrogen. It is believed that a strong interaction is established between hydrogen and the delocalized p-electrons present in the graphite layers and therefore a new type of chemistry is occurring within these confined structures.

  2. Laboratory studies of the growth, sublimation, and light- scattering properties of single levitated ice particles

    Science.gov (United States)

    Bacon, Neil Julian

    2001-12-01

    I describe experiments to investigate the properties of microscopic ice particles. The goal of the work was to measure parameters that are important in cloud processes and radiative transfer, using a novel technique that avoids the use of substrates. The experiments were conducted in two separate electrodynamic balance chambers. Single, charged ice particles were formed from frost particles or from droplets frozen either homogeneously or heteroge neously with a bionucleant. The particles were trapped at temperatures between -38°C and -4°C and grown or sublimated according to the temperature gradient in the cham ber. I describe observations of breakup of sublimating frost particles, measurements of light scattering by hexagonal crystals, and observations of the morphology of ice particles grown from frozen water droplets and frost particles. The breaking strength of frost particles was an order of magnitude less than that of bulk ice. Light scattering features not previously observed were analyzed and related to crystal dimension. Initial results from a computer model failed to reproduce these features. The widths of scattering peaks suggest that surface roughness may play a role in determining the angular distribution of scattered light. Ice particle mass evolution was found to be consistent with diffusion- limited growth. Crystals grown slowly from frozen droplets adopted isometric habits, while faster growth resulted in thin side-planes, although there was not an exact correspondence between growth conditions and particle morphology. From the morphological transition, I infer lower limits for the critical supersaturation for layer nucleation on the prism face of 2.4% at -15°C, 4.4% at -20°C, and 3.1% at -25°C. Analytic expressions for the size dependence of facet stability are developed, indicating a strong dependence of stability on both crystal size and surface kinetics, and compared with data. I discuss the role of complex particle morphologies in

  3. CURVED WALLS: GRAIN GROWTH, SETTLING, AND COMPOSITION PATTERNS IN T TAURI DISK DUST SUBLIMATION FRONTS

    Energy Technology Data Exchange (ETDEWEB)

    McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Building., Ann Arbor, MI 48109 (United States); D' Alessio, P. [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, 58089 Morelia, Michoacán (Mexico); Espaillat, C. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Sargent, B. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Hernández, J., E-mail: melisma@umich.edu, E-mail: ncalvet@umich.edu, E-mail: lhartm@umich.edu, E-mail: lingleby@umich.edu, E-mail: p.dalessio@astrosmo.unam.mx, E-mail: cespaillat@cfa.harvard.edu, E-mail: baspci@rit.edu, E-mail: dmw@pas.rochester.edu, E-mail: hernandj@cida.ve [Centro de Investigaciones de Astronomía (CIDA), Mérida 5101-A (Venezuela, Bolivarian Republic of)

    2013-10-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best fits to the near- and mid-IR excesses are found for curved, two-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe) = 0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10{sup –8} to 10{sup –10} M{sub ☉} yr{sup –1}, the maximum grain size in the lower layer decreases from ∼3 to 0.5 μm. We attribute this to a decrease in fragmentation and turbulent support for micron-sized grains with decreasing viscous heating. The atmosphere of these disks is depleted of dust with dust-gas mass ratios 1 × 10{sup –4} of the interstellar medium (ISM) value, while the midplane is enhanced to eight times the ISM value. For all accretion rates, the wall contributes at least half of the flux in the optically thin 10 μm silicate feature. Finally, we find evidence for an iron gradient in the disk, suggestive of that found in our solar system.

  4. The political sublime. reading Kok Nam, Mozambican photographer (1939-2012

    Directory of Open Access Journals (Sweden)

    Rui Assubuji

    Full Text Available Kok Nam began his photographic career at Studio Focus in Lourenco Marques in the 1950s, graduated to the newspaper Noticias and joined Tempo magazine in the early 1970s. Most recently he worked at the journal Savana as a photojournalist and later director. This article opens with an account of the relationship that developed between Kok Nam and the late President Samora Machel, starting with the photographer's portrait of Machel in Nachingwea in November 1974 before Independence. It traces an arc through the Popular Republic (1976-1990 from political revelation at its inception to the difficult years of civil war and Machel's death in the plane crash at Mbuzini in 1986. The article then engages in a series of photo-commentaries across a selection of Kok Nam's photographs, several published in their time but others selected retrospectively by Kok Nam for later exhibition and circulation. The approach taken is that of 'association', exploring the connections between the photographs, their histories both then and in the intervening years and other artifacts and mediums of cultural expression that deal with similar issues or signifiers picked up in the images. Among the signifiers picked up in the article are soldiers, pigs, feet, empty villages, washing, doves and bridges. The central argument is that Kok Nam participated with many others in a kind of collective hallucination during the Popular Republic, caught up in the 'political sublime'. Later Kok Nam shows many signs of a photographic 'second thinking' that sought out a more delicate sublime in his own archive.

  5. CURVED WALLS: GRAIN GROWTH, SETTLING, AND COMPOSITION PATTERNS IN T TAURI DISK DUST SUBLIMATION FRONTS

    International Nuclear Information System (INIS)

    McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L.; D'Alessio, P.; Espaillat, C.; Sargent, B.; Watson, D. M.; Hernández, J.

    2013-01-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best fits to the near- and mid-IR excesses are found for curved, two-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe) = 0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10 –8 to 10 –10 M ☉ yr –1 , the maximum grain size in the lower layer decreases from ∼3 to 0.5 μm. We attribute this to a decrease in fragmentation and turbulent support for micron-sized grains with decreasing viscous heating. The atmosphere of these disks is depleted of dust with dust-gas mass ratios 1 × 10 –4 of the interstellar medium (ISM) value, while the midplane is enhanced to eight times the ISM value. For all accretion rates, the wall contributes at least half of the flux in the optically thin 10 μm silicate feature. Finally, we find evidence for an iron gradient in the disk, suggestive of that found in our solar system

  6. Iapetus Surface Temperatures, and the Influence of Sublimation on the Albedo Dichotomy: Cassini CIRS Constraints

    Science.gov (United States)

    Spencer, J. R.; Pearl, J. C.; Segura, M.; Cassini CIRS Team

    2005-08-01

    The Composite Infrared Spectrometer (CIRS) on the Cassini orbiter obtained extensive observations of Iapetus' thermal emission during the New Year 2005 flyby, with best 8 - 16 μ m spatial resolution of 35 km per pixel. Observed subsolar temperatures on the dark terrain reach nearly 130 K, much warmer than any other satellite surface in the Saturn system, due to the combination of low albedo and slow rotation. These high temperatures mean that, uniquely in the Saturn system, water ice sublimation rates are significant at low latitudes on Iapetus' dark side, and surface water ice is probably not stable there on geological timescales. This result is consistent with the lack of water ice at low latitudes on the dark terrain inferred from Cassini UVIS UV spectra (Hendrix et al., 2005 LPSC). Thermally-controlled migration of water ice may thus contribute to the curious shape of the light/dark boundary on Iapetus, with bright poles and dark terrain extending round the equator onto the trailing side. Impacts of Saturn-centric or prograde heliocentric material cannot alone explain this shape, as their impact flux depends only on distance from the apex of motion (though the impact distribution of Oort cloud comet dust may be consistent with the observed albedo pattern (Cook and Franklin 1970)). We model the ballistic migration of water ice across the surface of Iapetus, determining temperatures and sublimation rates assuming CIRS-constrained thermal inertia and a simple dependence of albedo on distance from the apex of motion. Water ice is lost rapidly from low latitudes on the dark leading side and accumulates near the poles, and is also lost, though more slowly, in equatorial regions near the sub-Saturn and anti-Saturn points. The resulting water ice distribution pattern matches the distribution of Iapetus' bright terrain remarkably well. Albedo modification by thermal migration can thus help to reconcile Iapetus' albedo patterns with albedo control by Saturn-centric or

  7. Taking a Hike and Hucking the Stout: The Troublesome Legacy of the Sublime in Outdoor Recreation

    Directory of Open Access Journals (Sweden)

    Georg Drennig

    2013-12-01

    Full Text Available As Henry Thoreau noted in the 1850s, the simple act of walking can be loaded with political and spiritual meaning. Today, taking a hike as an act of engaging in outdoor recreation is equally non-trivial, and therefore subject of the following analysis. As this paper argues, outdoors recreation is still influenced by the legacy of the Sublime and its construction of wilderness. This troublesome legacy means that the cultural self-representation of outdoor sports – and the practice itself – lays claim to the environment in ways that are socially and sometimes even ethni-cally exclusive. This essay uses William Cronon’s critique of the cultural constructedness of wilderness as a point of departure to see how Western notions of sublime nature have an impact on spatial practice. The elevation of specific parts of the environ-ment into the category of wilderness prescribes certain uses and meanings as na-ture is made into an antidote against the ills of industrial civilization, and a place where the alienated individual can return to a more authentic self. This view then has become a troublesome legacy, informing the cultural self-representation of those uses of “wilderness” that are known as outdoor recreation. In its cultural production, outdoors recreation constructs “healthy” and “athlet-ic” bodies exercising in natural settings and finding refuge from the everyday al-ienation of postmodern society. Yet these bodies are conspicuously white, and the obligatory equipment and fashion expensive. Outdoor recreation is a privileged assertion of leisure, often denoting an urban, affluent, and white, background of the practitioner. These practitioners then lay exclusive claim on the landscapes they use. As trivial as taking a hike or any other form of outdoors recreation may thus seem, they put a cultural legacy into practice that is anything but trivial.

  8. Fe embedded in ice: The impacts of sublimation and energetic particle bombardment

    Science.gov (United States)

    Frankland, Victoria L.; Plane, John M. C.

    2015-05-01

    Icy particles containing a variety of Fe compounds are present in the upper atmospheres of planets such as the Earth and Saturn. In order to explore the role of ice sublimation and energetic ion bombardment in releasing Fe species into the gas phase, Fe-dosed ice films were prepared under UHV conditions in the laboratory. Temperature-programmed desorption studies of Fe/H2O films revealed that no Fe atoms or Fe-containing species co-desorbed along with the H2O molecules. This implies that when noctilucent ice cloud particles sublimate in the terrestrial mesosphere, the metallic species embedded in them will coalesce to form residual particles. Sputtering of the Fe-ice films by energetic Ar+ ions was shown to be an efficient mechanism for releasing Fe into the gas phase, with a yield of 0.08 (Ar+ energy=600 eV). Extrapolating with a semi-empirical sputtering model to the conditions of a proton aurora indicates that sputtering by energetic protons (>100 keV) should also be efficient. However, the proton flux in even an intense aurora will be too low for the resulting injection of Fe species into the gas phase to compete with that from meteoric ablation. In contrast, sputtering of the icy particles in the main rings of Saturn by energetic O+ ions may be the source of recently observed Fe+ in the Saturnian magnetosphere. Electron sputtering (9.5 keV) produced no detectable Fe atoms or Fe-containing species. Finally, it was observed that Fe(OH)2 was produced when Fe was dosed onto an ice film at 140 K (but not at 95 K). Electronic structure theory shows that the reaction which forms this hydroxide from adsorbed Fe has a large barrier of about 0.7 eV, from which we conclude that the reaction requires both translationally hot Fe atoms and mobile H2O molecules on the ice surface.

  9. Nuclear graphite based on coal tar pitch; behavior under neutron irradiation between 400 and 14000C

    International Nuclear Information System (INIS)

    Mottet, P.; Fillatre, A.; Schill, R.; Micaud, G.

    1977-01-01

    Two nuclear grades of coal tar pitch coke graphites have been developed and tested under neutron irradiation. The neutron irradiation induced dimensional changes between 400 and 1400 0 C, at fluences up to 1,2.10 22 n.cm -2 PHI.FG show a behavior comparable to anisotropic petroleum coke graphites. Less than 10% variation in thermal expansion, maximum decrease by a factor four in thermal conductivity, and large increase of the Young modulus have been observed

  10. Thermal desorption of formamide and methylamine from graphite and amorphous water ice surfaces

    Science.gov (United States)

    Chaabouni, H.; Diana, S.; Nguyen, T.; Dulieu, F.

    2018-04-01

    Context. Formamide (NH2CHO) and methylamine (CH3NH2) are known to be the most abundant amine-containing molecules in many astrophysical environments. The presence of these molecules in the gas phase may result from thermal desorption of interstellar ices. Aims: The aim of this work is to determine the values of the desorption energies of formamide and methylamine from analogues of interstellar dust grain surfaces and to understand their interaction with water ice. Methods: Temperature programmed desorption (TPD) experiments of formamide and methylamine ices were performed in the sub-monolayer and monolayer regimes on graphite (HOPG) and non-porous amorphous solid water (np-ASW) ice surfaces at temperatures 40-240 K. The desorption energy distributions of these two molecules were calculated from TPD measurements using a set of independent Polanyi-Wigner equations. Results: The maximum of the desorption of formamide from both graphite and ASW ice surfaces occurs at 176 K after the desorption of H2O molecules, whereas the desorption profile of methylamine depends strongly on the substrate. Solid methylamine starts to desorb below 100 K from the graphite surface. Its desorption from the water ice surface occurs after 120 K and stops during the water ice sublimation around 150 K. It continues to desorb from the graphite surface at temperatures higher than160 K. Conclusions: More than 95% of solid NH2CHO diffuses through the np-ASW ice surface towards the graphitic substrate and is released into the gas phase with a desorption energy distribution Edes = 7460-9380 K, which is measured with the best-fit pre-exponential factor A = 1018 s-1. However, the desorption energy distribution of methylamine from the np-ASW ice surface (Edes = 3850-8420 K) is measured with the best-fit pre-exponential factor A = 1012 s-1. A fraction of solid methylamine monolayer of roughly 0.15 diffuses through the water ice surface towards the HOPG substrate. This small amount of methylamine

  11. Methane generated from graphite--tritium interaction

    International Nuclear Information System (INIS)

    Coffin, D.O.; Walthers, C.R.

    1979-01-01

    When hydrogen isotopes are separated by cryogenic distillation, as little as 1 ppM of methane will eventually plug the still as frost accumulates on the column packings. Elemental carbon exposed to tritium generates methane spontaneously, and yet some dry transfer pumps, otherwise compatible with tritium, convey the gas with graphite rotors. This study was to determine the methane production rate for graphite in tritium. A pump manufacturer supplied graphite samples that we exposed to tritium gas at 0.8 atm. After 137 days we measured a methane synthesis rate of 6 ng/h per cm 2 of graphite exposed. At this rate methane might grow to a concentration of 0.01 ppM when pure tritium is transferred once through a typical graphite--rotor transfer pump. Such a low methane level will not cause column blockage, even if the cryogenic still is operated continuously for many years

  12. Chemical sputtering of graphite by H+ ions

    International Nuclear Information System (INIS)

    Busharov, N.P.; Gorbatov, E.A.; Gusev, V.M.; Guseva, M.I.; Martynenko, Y.V.

    1976-01-01

    In a study of the sputtering coefficient S for the sputtering of graphite by 10-keV H + ions as a function of the graphite temperature during the bombardment, it is found that at T> or =750degreeC the coefficient S is independent of the target temperature and has an anomalously high value, S=0.085 atom/ion. The high rate of sputtering of graphite by atomic hydrogen ions is shown to be due to chemical sputtering of the graphite, resulting primarily in the formation of CH 4 molecules. At T=1100degreeC, S falls off by a factor of about 3. A model for the chemical sputtering of graphite is proposed

  13. Sublimation of icy planetesimals and the delivery of water to the habitable zone around solar type stars

    Science.gov (United States)

    Brunini, Adrián; López, María Cristina

    2018-06-01

    We present a semi analytic model to evaluate the delivery of water to the habitable zone around a solar type star carried by icy planetesimals born beyond the snow line. The model includes sublimation of ice, gas drag and scattering by an outer giant planet located near the snow line. The sublimation model is general and could be applicable to planetary synthesis models or N-Body simulations of the formation of planetary systems. We perform a short series of simulations to asses the potential relevance of sublimation of volatiles in the process of delivery of water to the inner regions of a planetary system during early stages of its formation. We could anticipate that erosion by sublimation would prevent the arrival of much water to the habitable zone of protoplanetary disks in the form of icy planetesimals. Close encounters with a massive planet orbiting near the outer edge of the snow line could make possible for planetesimals to reach the habitable zone somewhat less eroded. However, only large planetesimals could provide appreciable amounts of water. Massive disks and sharp gas surface density profiles favor icy planetesimals to reach inner regions of a protoplanetary disk.

  14. Thermodynamic study of alkane-α,ω-diamines - evidence of odd-even pattern of sublimation properties

    Czech Academy of Sciences Publication Activity Database

    Fulem, Michal; Růžička, K.; Červinka, C.; Bazyleva, A.; Della Gatta, G.

    2014-01-01

    Roč. 371, Jun (2014), s. 93-105 ISSN 0378-3812 Institutional support: RVO:68378271 Keywords : alkane-diamines * odd–even effect * vapor pressure * sublimation and vaporization thermodynamic properties * statistical thermodynamics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.200, year: 2014

  15. Conditioning for definitive storage of radioactive graphite bricks from reactor decommissioning

    International Nuclear Information System (INIS)

    Costes, J.R.; Koch, C.; Tassigny, C. de; Vidal, H.; Raymond, A.

    1990-01-01

    The decommissioning of gas-graphite reactors in the EC (e.g. French UNGGs, British Magnox reactors and AGRs, and reactors in Spain and in Italy) will produce large amounts of graphite bricks. This graphite cannot be accepted without particular conditioning by the existing shallow land disposal sites. The aim of the study is to examine the behaviour of graphite waste and to develop a conditioning technique which makes this waste acceptable for shallow land disposal sites. 18 kg of graphite core samples with an outside diameter of 74 mm were removed from the G2 gas-cooled reactor at Marcoule. Their radioactivity is highly dependent on the position of the graphite bricks inside the reactor. Measured results indicate an activity range of 100-400 MBq/kg with 90% Tritium, 5% 14 C, 3% 60 Co, 1.5% 63 Ni. Repeated porosity analyses showed that open porosity ranging from 0 to 100 μm exceeded 23 vol% in the graphite. Water penetration kinetics were investigated in unimpregnated graphite and resulted in impregnation by water of 50-90% of the open porosity. Preliminary lixiviation tests on the crude samples showed quick lixidegree of Cs (several per cent) and of 60 Co, and 133 Ba at a lesser degree. The proposed conditioning technique does not involve a simple coating but true impregnation by a tar-epoxy mixture. The bricks recovered intact from the core by robot services will be placed one by one inside a cylindrical metallic container. But this container may corrode and the bricks may become fragmented in the future, the normally porous graphite will be unaffected by leaching since it is proved that all pores larger than 0.1 μm will be filled with the tar-epoxy mixture. This is a true long-term waste packaging concept. The very simple technology required for industrial implementation is discussed

  16. Comparison of the oxidation rate and degree of graphitization of selected IG and NBG nuclear graphite grades

    Science.gov (United States)

    Chi, Se-Hwan; Kim, Gen-Chan

    2008-10-01

    The oxidation rate and degree of graphitization (DOG) were determined for some selected nuclear graphite grades (i.e., IG-110, IG-430, NBG-18, NBG-25) and compared in view of their filler coke type (i.e., pitch or petroleum coke) and the physical property of the grades. Oxidation rates were determined at six temperatures between 600 and 960 °C in air by using a three-zone vertical tube furnace at a 10 l/min air flow rate. The specimens were a cylinder with a 25.4 mm diameter and a 25.4 mm length. The DOG was determined based on the lattice parameter c determined from an X-ray diffraction (XRD). Results showed that, even though the four examined nuclear graphite grades showed a highly temperature-sensitive oxidation behavior through out the test temperature range of 600-950 °C, the differences between the grades were not significant. The oxidation rates determined for a 5-10% weight loss at the six temperatures were nearly the same except for 702 and 808 °C, where the pitch coke graphites showed an apparent decrease in their oxidation rate, more so than the petroleum coke graphites. These effects of the coke type reduced or nearly disappeared with an increasing temperature. The average activation energy determined for 608-808 °C was 161.5 ± 7.3 kJ/mol, showing that the dominant oxidation reaction occurred by a chemical control. A relationship between the oxidation rate and DOG was not observed.

  17. Comparison of the oxidation rate and degree of graphitization of selected IG and NBG nuclear graphite grades

    International Nuclear Information System (INIS)

    Chi, Se-Hwan; Kim, Gen-Chan

    2008-01-01

    The oxidation rate and degree of graphitization (DOG) were determined for some selected nuclear graphite grades (i.e., IG-110, IG-430, NBG-18, NBG-25) and compared in view of their filler coke type (i.e., pitch or petroleum coke) and the physical property of the grades. Oxidation rates were determined at six temperatures between 600 and 960 deg. C in air by using a three-zone vertical tube furnace at a 10 l/min air flow rate. The specimens were a cylinder with a 25.4 mm diameter and a 25.4 mm length. The DOG was determined based on the lattice parameter c determined from an X-ray diffraction (XRD). Results showed that, even though the four examined nuclear graphite grades showed a highly temperature-sensitive oxidation behavior through out the test temperature range of 600-950 deg. C, the differences between the grades were not significant. The oxidation rates determined for a 5-10% weight loss at the six temperatures were nearly the same except for 702 and 808 deg. C, where the pitch coke graphites showed an apparent decrease in their oxidation rate, more so than the petroleum coke graphites. These effects of the coke type reduced or nearly disappeared with an increasing temperature. The average activation energy determined for 608-808 deg. C was 161.5 ± 7.3 kJ/mol, showing that the dominant oxidation reaction occurred by a chemical control. A relationship between the oxidation rate and DOG was not observed

  18. Modeling Fission Product Sorption in Graphite Structures

    International Nuclear Information System (INIS)

    Szlufarska, Izabela; Morgan, Dane; Allen, Todd

    2013-01-01

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high-temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission products

  19. HTGR Fuels and Core Development Program. Quarterly progress report for the period ending August 31, 1977. [Graphite and fuel irradiation; fission product release

    Energy Technology Data Exchange (ETDEWEB)

    1977-09-01

    The work reported includes studies of reactions between core materials and coolant impurities, basic fission product transport mechanisms, core graphite development and testing, the development and testing of recyclable fuel systems, and physics and fuel management studies. Materials studies include irradiation capsule tests of both fuel and graphite. Experimental procedures and results are discussed and data are presented.

  20. Synthesis and Characterization of Highly Intercalated Graphite Bisulfate

    OpenAIRE

    Salvatore, Marcella; Carotenuto, Gianfranco; De Nicola, Sergio; Camerlingo, Carlo; Ambrogi, Veronica; Carfagna, Cosimo

    2017-01-01

    Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtain...

  1. Non-destructive evaluation on mechanical properties of nuclear graphite with porous structure

    International Nuclear Information System (INIS)

    Shibata, Taiju; Hanawa, Satoshi; Sumita, Junya; Tada, Tatsuya; Sawa, Kazuhiro; Iyoku, Tatsuo

    2005-01-01

    As a research subjects of 'Research and development for advanced high temperature gas cooled reactor fuels and graphite components,' we started the study of development of non-destructive evaluation methods for mechanical properties of graphite components. The micro-indentation and ultrasonic wave methods are focused to evaluate the degradation of graphite components in VHTR core. For the micro-indentation method, the test apparatus was designed for the indentation test on graphite specimens with some stress levels. It is expected the stress condition is evaluated by the indentation load-depth characteristics and hardness. For the ultrasonic wave method, ultrasonic wave testing machine and probes were prepared for experiments. It is expected that the stress and inner porous conditions are evaluated by the wave propagation characteristics with wave-pore interaction model. R and D plan to develop the non-destructive evaluation method for graphite is presented in this paper. (This study is the result of contract research in the fiscal year of 2004, Research and development for advanced high temperature gas cooled reactor fuels and graphite components,' which is entrusted to the Japan Atomic Energy Research Institute from the Ministry of Education, Culture, Sports, Science and Technology of Japan.) (author)

  2. Graphite Foam Heat Exchangers for Thermal Management

    Energy Technology Data Exchange (ETDEWEB)

    Klett, J.W.

    2004-06-07

    Improved thermal management is needed to increase the power density of electronic and more effectively cool electronic enclosures that are envisioned in future aircraft, spacecraft and surface ships. Typically, heat exchanger cores must increase in size to more effectively dissipate increased heat loads, this would be impossible in many cases, thus improved heat exchanger cores will be required. In this Phase I investigation, MRi aimed to demonstrate improved thermal management using graphite foam (Gr-foam) core heat exchangers. The proposed design was to combine Gr-foams from POCO with MRi's innovative low temperature, active metal joining process (S-Bond{trademark}) to bond Gr-foam to aluminum, copper and aluminum/SiC composite faceplates. The results were very favorable, so a Phase II SBIR with the MDA was initiated. This had primarily 5 tasks: (1) bonding, (2) thermal modeling, (3) cooling chip scale packages, (4) evaporative cooling techniques and (5) IGBT cold plate development. The bonding tests showed that the ''reflow'' technique with S-Bond{reg_sign}-220 resulted in the best and most consistent bond. Then, thermal modeling was used to design different chip scale packages and IGBT cold plates. These designs were used to fabricate many finned graphite foam heat sinks specifically for two standard type IC packages, the 423 and 478 pin chips. These results demonstrated several advantages with the foam. First, the heat sinks with the foam were lighter than the copper/aluminum sinks used as standards. The sinks for the 423 design made from foam were not as good as the standard sinks. However, the sinks made from foam for the 478 pin chips were better than the standard heat sinks used today. However, this improvement was marginal (in the 10-20% better regime). However, another important note was that the epoxy bonding technique resulted in heat sinks with similar results as that with the S-bond{reg_sign}, slightly worse than the S

  3. SEM/XPS analysis of fractured adhesively bonded graphite fibre surface resin-rich/graphite fibre composites

    Science.gov (United States)

    Devilbiss, T. A.; Wightman, J. P.; Progar, D. J.

    1988-01-01

    Samples of graphite fiber-reinforced polyimide were fabricated allowing the resin to accumulate at the composite surface. These surface resin-rich composites were then bonded together and tested for lap shear strength both before and after thermal aging. Lap shear strength did not appear to show a significant improvement over that previously recorded for resin-poor samples and was shown to decrease with increasing aging time and temperature.

  4. Proton irradiated graphite grades for a long baseline neutrino facility experiment

    International Nuclear Information System (INIS)

    Simos, N.; Nocera, P.; Zwaska, R.; Mokhov, N.

    2017-01-01

    In search of a low-Z pion production target for the Long Baseline Neutrino Facility (LBNF) of the Deep Underground Neutrino Experiment (DUNE) four graphite grades were irradiated with protons in the energy range of 140–180 MeV, to peak fluence of ~6.1×10"2"0 p/cm"2 and irradiation temperatures between 120–200 °C. The test array included POCO ZXF-5Q, Toyo-Tanso IG 430, Carbone-Lorraine 2020 and SGL R7650 grades of graphite. Irradiation was performed at the Brookhaven Linear Isotope Producer. Postirradiation analyses were performed with the objective of (a) comparing their response under the postulated irradiation conditions to guide a graphite grade selection for use as a pion target and (b) understanding changes in physical and mechanical properties as well as microstructure that occurred as a result of the achieved fluence and in particular at this low-temperature regime where pion graphite targets are expected to operate. A further goal of the postirradiation evaluation was to establish a proton-neutron correlation damage on graphite that will allow for the use of a wealth of available neutron-based damage data in proton-based studies and applications. Macroscopic postirradiation analyses as well as energy dispersive x-ray diffraction of 200 KeV x rays at the NSLS synchrotron of Brookhaven National Laboratory were employed. The macroscopic analyses revealed differences in the physical and strength properties of the four grades with behavior however under proton irradiation that qualitatively agrees with that reported for graphite under neutrons for the same low temperature regime and in particular the increase of thermal expansion, strength and Young’s modulus. The proton fluence level of ~10"2"0 cm"-"2 where strength reaches a maximum before it begins to decrease at higher fluences has been identified and it agrees with neutron-induced changes. X-ray diffraction analyses of the proton irradiated graphite revealed for the first time the similarity in

  5. Proton irradiated graphite grades for a long baseline neutrino facility experiment

    Science.gov (United States)

    Simos, N.; Nocera, P.; Zhong, Z.; Zwaska, R.; Mokhov, N.; Misek, J.; Ammigan, K.; Hurh, P.; Kotsina, Z.

    2017-07-01

    In search of a low-Z pion production target for the Long Baseline Neutrino Facility (LBNF) of the Deep Underground Neutrino Experiment (DUNE) four graphite grades were irradiated with protons in the energy range of 140-180 MeV, to peak fluence of ˜6.1 ×1020 p /cm2 and irradiation temperatures between 120 - 200 °C . The test array included POCO ZXF-5Q, Toyo-Tanso IG 430, Carbone-Lorraine 2020 and SGL R7650 grades of graphite. Irradiation was performed at the Brookhaven Linear Isotope Producer. Postirradiation analyses were performed with the objective of (a) comparing their response under the postulated irradiation conditions to guide a graphite grade selection for use as a pion target and (b) understanding changes in physical and mechanical properties as well as microstructure that occurred as a result of the achieved fluence and in particular at this low-temperature regime where pion graphite targets are expected to operate. A further goal of the postirradiation evaluation was to establish a proton-neutron correlation damage on graphite that will allow for the use of a wealth of available neutron-based damage data in proton-based studies and applications. Macroscopic postirradiation analyses as well as energy dispersive x-ray diffraction of 200 KeV x rays at the NSLS synchrotron of Brookhaven National Laboratory were employed. The macroscopic analyses revealed differences in the physical and strength properties of the four grades with behavior however under proton irradiation that qualitatively agrees with that reported for graphite under neutrons for the same low temperature regime and in particular the increase of thermal expansion, strength and Young's modulus. The proton fluence level of ˜1020 cm-2 where strength reaches a maximum before it begins to decrease at higher fluences has been identified and it agrees with neutron-induced changes. X-ray diffraction analyses of the proton irradiated graphite revealed for the first time the similarity in

  6. Diffusion of cesium and iodine in compressed IG-110 graphite compacts

    International Nuclear Information System (INIS)

    Carter, L.M.; Brockman, J.D.; Robertson, J.D.; Loyalka, S.K.

    2016-01-01

    Nuclear graphite grade IG-110 is currently used in the High Temperature Engineering Test Reactor (HTTR) in Japan for certain permanent and replaceable core components, and is a material of interest in general. Therefore, transport parameters for fission products in this material are needed. Measurement of diffusion through pressed compacts of IG-110 graphite is experimentally attractive because they are easy to prepare with homogeneous distributions of fission product surrogates. In this work, we measured diffusion coefficients for Cs and I in pressed compacts made from IG-110 powder in the 1079–1290 K temperature range, and compared them to those obtained in as-received IG-110. - Highlights: • A method for analysis of fission product diffusion in graphite by ICP-MS was applied to pressed IG-110 graphite compacts containing cesium and iodine. • Diffusion coefficients for cesium and iodine were obtained. • The measurement design simulates HTGR conditions of high temperature and flowing helium.

  7. Optimization of Sealed Tube Graphitization Method for Environmental C-14 Studies Using MICADAS

    Energy Technology Data Exchange (ETDEWEB)

    Rinyu, Laszlo, E-mail: rinyu@atomki.hu [Hertelendi Laboratory of Environmental Studies, Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Isotoptech Zrt., H-4025 Debrecen (Hungary); Molnar, Mihaly [Hertelendi Laboratory of Environmental Studies, Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Ion Beam Physics, ETH Zuerich, CH-8093 Zuerich (Switzerland); Major, Istvan [Hertelendi Laboratory of Environmental Studies, Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Nagy, Tamas; Veres, Mihaly [Isotoptech Zrt., H-4025 Debrecen (Hungary); Kimak, Adam [University of Debrecen, H-4032 Debrecen (Hungary); Wacker, Lukas; Synal, Hans-Arno [Ion Beam Physics, ETH Zuerich, CH-8093 Zuerich (Switzerland)

    2013-01-15

    The original sealed tube zinc reduction graphitization process was first developed for rapid low-precision measurements of biomedical tracer samples and later also applied for high precision measurements of not too old samples. In this study we tested the MICADAS (mini radiocarbon dating system [1]) radiocarbon measurements of targets prepared by sealed tube graphitization process. We found the optimal iron catalyst and reagents (TiH{sub 2} and Zn) amount whereby we can reach a relatively low background level, and minimized the overall {delta}{sup 13}C fractionation during the graphitization. Repeated measurements of normalization standards and real samples with known {sup 14}C activities were very well reproduced. Finally, we demonstrated the applicability of the sealed tube graphitization on real environmental samples covering a wide range of {sup 14}C concentrations.

  8. Wear Behavior of Selected Nuclear Grade Graphites at Room Temperature in Ambient Air Environment

    International Nuclear Information System (INIS)

    Kim, Eung-Seon; Park, Kwang-Seok; Kim, Yong-Wan

    2008-01-01

    In a very high temperature reactor (VHTR), graphite will be used not only for as a moderator and reflector but also as a major structural component due to its excellent neutronic, thermal and mechanical properties. In the VHTR, wear of graphite components is inevitable due to a neutron irradiation-induced dimensional change, thermal gradient, relative motions of graphite components and a shock load such as an earthquake. Large wear particles accumulated at the bottom of a reactor can influence the cooling of the lower part and small wear particles accumulated on the primary circuit and heat exchanger tube can make it difficult to inspect the equipment, and also decrease the heat exchange rate. In the present work, preliminary wear tests were performed at room temperature in ambient air environment to understand the basic wear characteristics of selected nuclear grade graphites for the VHTR

  9. Electrochemical catalytic activity of tungsten trioxide- modified graphite felt toward VO2+/VO2+ redox reaction

    International Nuclear Information System (INIS)

    Shen, Yang; Xu, Hongfeng; Xu, Pengcheng; Wu, Xiaoxin; Dong, Yiming; Lu, Lu

    2014-01-01

    A novel graphite felt electrode modified with tungsten trioxide (WO 3 ) was developed to improve the electrochemical performance of graphite felt toward the VO 2 + /VO 2+ redox pair. WO 3 was prepared using a hydrothermal method, and the morphology of WO 3 structures was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical property of WO 3 -modified graphite felt toward VO 2 + /VO 2+ was carefully characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The hydrogen-vanadium redox flow battery (H-VRFB) test indicates that single cells using 1.1 mg cm −2 WO 3 -modified graphite felt exhibited excellent performance at 70 mA cm −2 , and the corresponding coulombic, voltage, and energy efficiencies were 99.1%, 88.66% and 87.86%, respectively

  10. Graphite Oxidation Thermodynamics/Reactions

    International Nuclear Information System (INIS)

    Propp, W.A.

    1998-01-01

    The vulnerability of graphite-matrix spent nuclear fuel to oxidation by the ambient atmosphere if the fuel canister is breached was evaluated. Thermochemical and kinetic data over the anticipated range of storage temperatures (200 to 400 C) were used to calculate the times required for a total carbon mass loss of 1 mgcm-2 from a fuel specimen. At 200 C, the time required to produce even this small loss is large, 900,000 yr. However, at 400 C the time required is only 1.9 yr. The rate of oxidation at 200 C is negligible, and the rate even at 400 C is so small as to be of no practical consequence. Therefore, oxidation of the spent nuclear fuel upon a loss of canister integrity is not anticipated to be a concern based upon the results of this study

  11. Deposition of tantalum carbide coatings on graphite by laser interactions

    Science.gov (United States)

    Veligdan, James; Branch, D.; Vanier, P. E.; Barietta, R. E.

    1994-01-01

    Graphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000 C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCl5 gas near the substrate. The results of preliminary experiments using these techniques are described.

  12. Channel uranium-graphite reactor mounting

    International Nuclear Information System (INIS)

    Polushkin, K.K.; Kuznetsov, A.G.; Zheleznyakov, B.N.

    1981-01-01

    According to theoretical principles of general engineering technology the engineering experience of construction-mounting works at the NPP with channel uranium-graphite reactors is systematized. Main parameters and structural features of the 1000 MW channel uranium-graphite reactors are considered. The succession of mounting operations, premounting equipment and pipelines preparation and mounting works technique are described. The most efficient methods of fitting, welding and machining of reactor elements are recommended. Main problems of technical control service are discussed. A typical netted diagram of main equipment of channel uranium-graphite reactors mounting is given

  13. Synthesis of soluble graphite and graphene.

    Science.gov (United States)

    Kelly, K F; Billups, W E

    2013-01-15

    Because of graphene's anticipated applications in electronics and its thermal, mechanical, and optical properties, many scientists and engineers are interested in this material. Graphene is an isolated layer of the π-stacked hexagonal allotrope of carbon known as graphite. The interlayer cohesive energy of graphite, or exfoliation energy, that results from van der Waals attractions over the interlayer spacing distance of 3.34 Å (61 meV/C atom) is many times weaker than the intralayer covalent bonding. Since graphene itself does not occur naturally, scientists and engineers are still learning how to isolate and manipulate individual layers of graphene. Some researchers have relied on the physical separation of the sheets, a process that can sometimes be as simple as peeling of sheets from crystalline graphite using Scotch tape. Other researchers have taken an ensemble approach, where they exploit the chemical conversion of graphite to the individual layers. The typical intermediary state is graphite oxide, which is often produced using strong oxidants under acidic conditions. Structurally, researchers hypothesize that acidic functional groups functionalize the oxidized material at the edges and a network of epoxy groups cover the sp(2)-bonded carbon network. The exfoliated material formed under these conditions can be used to form dispersions that are usually unstable. However, more importantly, irreversible defects form in the basal plane during oxidation and remain even after reduction of graphite oxide back to graphene-like material. As part of our interest in the dissolution of carbon nanomaterials, we have explored the derivatization of graphite following the same procedures that preserve the sp(2) bonding and the associated unique physical and electronic properties in the chemical processing of single-walled carbon nanotubes. In this Account, we describe efficient routes to exfoliate graphite either into graphitic nanoparticles or into graphene without

  14. Adsorption of lead over graphite oxide.

    Science.gov (United States)

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M; Oki, Aderemi

    2014-01-24

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption Spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb(2+) was found to be 98%, 91% and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water. Published by Elsevier B.V.

  15. Interface structure between tetraglyme and graphite

    Science.gov (United States)

    Minato, Taketoshi; Araki, Yuki; Umeda, Kenichi; Yamanaka, Toshiro; Okazaki, Ken-ichi; Onishi, Hiroshi; Abe, Takeshi; Ogumi, Zempachi

    2017-09-01

    Clarification of the details of the interface structure between liquids and solids is crucial for understanding the fundamental processes of physical functions. Herein, we investigate the structure of the interface between tetraglyme and graphite and propose a model for the interface structure based on the observation of frequency-modulation atomic force microscopy in liquids. The ordering and distorted adsorption of tetraglyme on graphite were observed. It is found that tetraglyme stably adsorbs on graphite. Density functional theory calculations supported the adsorption structure. In the liquid phase, there is a layered structure of the molecular distribution with an average distance of 0.60 nm between layers.

  16. Modified solution calorimetry approach for determination of vaporization and sublimation enthalpies of branched-chain aliphatic and alkyl aromatic compounds at T = 298.15 K

    International Nuclear Information System (INIS)

    Varfolomeev, Mikhail A.; Novikov, Vladimir B.; Nagrimanov, Ruslan N.; Solomonov, Boris N.

    2015-01-01

    Highlights: • Solution enthalpies of 18 branching-chain alkyl aromatic and aliphatic compounds in cyclohexane were measured. • Group contributions to the enthalpy of solvation due to branching and substitution in carbon chain were evaluated. • Modified solution calorimetry based approach for determination of vaporization/sublimation enthalpies was proposed. • This approach provides vaporization/sublimation enthalpies directly at T = 298.15 K. • Vaporization/sublimation enthalpies of 35 branched-chain alkyl aromatic and aliphatic compounds were determined. - Abstract: The enthalpies of solution, solvation and vaporization/sublimation are interrelated values combined in the simplest thermodynamic circle. Hence, experimental determination of vaporization/sublimation enthalpy can be substituted by experimentally simpler determination of solution enthalpy when solvation enthalpy is known. Previously it was found that solvation enthalpies of a wide range of unbranched aliphatic and aromatic solutes in saturated hydrocarbons are in good linear correlation with their molar refraction values. This allows to estimate the vaporization/sublimation enthalpy of any unbranched organic compound from its solution enthalpy in saturated hydrocarbon and molar refraction. In the present work this approach was modified for determination of vaporization/sublimation enthalpy of branched-chain alkyl aromatic and aliphatic compounds. Group contributions to the enthalpy of solvation due to the branching of carbon chain were evaluated. Enthalpies of solution at infinite dilution of 18 branched-chain aliphatic and alkyl aromatic compounds were measured at T = 298.15 K. Vaporization/sublimation enthalpies for 35 branched aliphatic and alkyl aromatic compounds were determined by using modified solution calorimetry approach. These values are in good agreement with available literature data on vaporization/sublimation enthalpies obtained by conventional methods.

  17. Superhydrophilic graphite surfaces and water-dispersible graphite colloids by electrochemical exfoliation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yueh-Feng [Department of Chemical and Materials Engineering, National Central University, Jhongli, 320 Taiwan (China); Chen, Shih-Ming; Lai, Wei-Hao [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung, Hsinchu, 31040 Taiwan (China); Sheng, Yu-Jane [Department of Chemical Engineering, National Taiwan University, Taipei, 106 Taiwan (China); Tsao, Heng-Kwong [Department of Chemical and Materials Engineering, Department of Physics, National Central University, Jhongli, 320 Taiwan (China)

    2013-08-14

    Superhydrophilic graphite surfaces and water-dispersible graphite colloids are obtained by electrochemical exfoliation with hydrophobic graphite electrodes. Such counterintuitive characteristics are caused by partial oxidation and investigated by examining both graphite electrodes and exfoliated particles after electrolysis. The extent of surface oxidation can be explored through contact angle measurement, scanning electron microscope, electrical sheet resistance, x-ray photoelectron spectroscopy, zeta-potential analyzer, thermogravimetric analysis, UV-visible, and Raman spectroscopy. The degree of wettability of the graphite anode can be altered by the electrolytic current and time. The water contact angle declines generally with increasing the electrolytic current or time. After a sufficient time, the graphite anode becomes superhydrophilic and its hydrophobicity can be recovered by peeling with adhesive tape. This consequence reveals that the anodic graphite is oxidized by oxygen bubbles but the oxidation just occurs at the outer layers of the graphite sheet. Moreover, the characteristics of oxidation revealed by UV peak shift, peak ratio between D and G bands, and negative zeta-potential indicate the presence of graphite oxide on the outer shell of the exfoliated colloids. However, thermogravimetric analysis for the extent of decomposition of oxygen functional groups verifies that the amount of oxygen groups is significantly less than that of graphite oxide prepared via Hummer method. The structure of this partially oxidized graphite may consist of a graphite core covered with an oxidized shell. The properties of the exfoliated colloids are also influenced by pH of the electrolytic solution. As pH is increased, the extent of oxidation descends and the thickness of oxidized shell decreases. Those results reveal that the degree of oxidation of exfoliated nanoparticles can be manipulated simply by controlling pH.

  18. Performance of AC/graphite capacitors at high weight ratios of AC/graphite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongyu [IM and T Ltd., Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki [Advanced Research Center, Department of Applied Chemistry, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

    2008-03-01

    The effect of negative to positive electrode materials' weight ratio on the electrochemical performance of both activated carbon (AC)/AC and AC/graphite capacitors has been investigated, especially in the terms of capacity and cycle-ability. The limited capacity charge mode has been proposed to improve the cycle performance of AC/graphite capacitors at high weight ratios of AC/graphite. (author)

  19. Management of radioactive waste in nuclear power: handling of irradiated graphite from water-cooled graphite reactors

    International Nuclear Information System (INIS)

    Anfimov, S.S.

    2001-01-01

    In this paper an radioactive waste processing of graphite from graphite moderated nuclear reactors at its decommissioning is discussed. Methods of processing of irradiated graphite are presented. It can be concluded that advanced methods for graphite radioactive waste handling are available nowadays. Implementation of these methods will allow to enhance environmental safety of nuclear power that will benefit its progress in the future

  20. A Graphite Isotope Ratio Method: A Primer on Estimating Plutonium Production in Graphite Moderated Reactors

    International Nuclear Information System (INIS)

    Gesh, Christopher J.

    2004-01-01

    The Graphite Isotope Ratio Method (GIRM) is a technique used to estimate the total plutonium production in a graphite-moderated reactor. The cumulative plutonium production in that reactor can be accurately determined by measuring neutron irradiation induced isotopic ratio changes in certain impurity elements within the graphite moderator. The method does not require detailed knowledge of a reactor's operating history, although that knowledge can decrease the uncertainty of the production estimate. The basic premise of the Graphite Isotope Ratio Method is that the fluence in non-fuel core components is directly related to the cumulative plutonium production in the nuclear fuel

  1. Characterization of fresh and irradiated domestic nuclear graphite; Karakterizacija neozracenog i ozracenog domaceg nuklearnog grafita

    Energy Technology Data Exchange (ETDEWEB)

    Marinkovic, S; Suznjevic, C; Bogdanovic, R; Gasic, M [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1965-11-15

    This report shows results of testing the quality of domestic impregnated graphite IGSP-05, and irradiated domestic graphite IGSP-01 as well as the new methos of characterization based on graphite oxidation by liquid agent. Systematic measurement of domestic impregnated graphite enabled conclusions related to its quality and further improvement. Domestic graphite is relatively well graphitized and its properties are approaching standard nuclear graphite, although it still shows some deficiencies. Important deficiencies are significant inhomogeneity and low density. The applied impregnation procedure did not improve significantly the quality of graphite, probably because the material which was impregnated had fine pores. To avoid this porosity it would be necessary to use material with higher granulation. Soot which was present in some blocks probably worsened the quality of graphite and caused dispersion of the obtained results. First tests of irradiated domestic graphite IGSP-01 showed that its behaviour does not differ from standard nuclear graphite in case of low doses. It is necessary to test its properties in case of higher neutron doses before drawing final conclusions. The new method of graphite oxidation by the N{sub 2}SO{sub 4} - Ag{sub 2}Cr{sub 2}O{sub 7} mixture which is highly sensitive on the existence of structural defects is based on detecting the oxidation rate of graphite by measuring the pressure of released CO{sub 2}. Application of the method for testing the domestic and American graphite showed that irradiation caused drastic changes of oxidation rates and similar behaviour of both graphite types. U ovom izvestaju su prikazani rezultati ispitivanja kvaliteta domaceg impregnisanog grafita IGSP-05, rezultati ispitivanja ozracenog domaceg grafita IGSP-01 i opisana je nova uvedena metoda karakterizacije zasnovana na oksidaciji grafita tecnim agensom. Sistematsko merenje osobina domaceg impregnisanog grafita je omogucilo donosenje zakljucaka o

  2. Synthesis of graphene nanoplatelets from peroxosulfate graphite intercalation compounds

    OpenAIRE

    MELEZHYK A.V.; TKACHEV A.G.

    2014-01-01

    Ultrasonic exfoliation of expanded graphite compound obtained by cold expansion of graphite intercalated with peroxodisulfuric acid was shown to allow the creation of graphene nanoplatelets with thickness of about 5-10 nm. The resulting graphene material contained surface oxide groups. The expanded graphite intercalation compound was exfoliated by ultrasound much easier than thermally expanded graphite. A mechanism for the cleavage of graphite to graphene nanoplatelets is proposed. It include...

  3. Graphite reactor physics; Physique des piles a graphite

    Energy Technology Data Exchange (ETDEWEB)

    Bacher, P; Cogne, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Noc, B [Electricite de France (EDF), 75 - Paris (France)

    1964-07-01

    The study of graphite-natural uranium power reactor physics, undertaken ten years ago when the Marcoule piles were built, has continued to keep in step with the development of this type of pile. From 1960 onwards the critical facility Marius has been available for a systematic study of the properties of lattices as a function of their pitch, of fuel geometry and of the diameter of cooling channels. This study has covered a very wide field: lattice pitch varying from 19 to 38 cm. uranium rods and tubes of cross-sections from 6 to 35 cm{sup 2}, channels with diameters between 70 and 140 mm. The lattice calculation methods could thus be checked and where necessary adapted. The running of the Marcoule piles and the experiments carried out on them during the last few years have supplied valuable information on the overall evolution of the neutronic properties of the fuel as a function of irradiation. More detailed experiments have also been performed in Marius with plutonium-containing fuels (irradiated or synthetic fuels), and will be undertaken at the beginning of 1965 at high temperature in the critical facility Cesar, which is just being completed at Cadarache. Spent fuel analyses complement these results and help in their interpretation. The thermalization and spectra theories developed in France can thus be verified over the whole valid temperature range. The efficiency of control rods as a function of their dimensions, the materials of which they are made and the lattices surrounding them has been measured in Marius, and the results compared with calculation on the one hand and with the measurements carried out in EDF 1 on the other. Studies on the control proper of graphite piles were concerned essentially with the risks of spatial instability and the means of detecting and controlling them, and with flux distortions caused by the control rods. (authors) [French] Entreprise il y a dix ans a l'occasion de la construction des piles de Marcoule, l'etude de la

  4. Seismic research on graphite reactor core

    International Nuclear Information System (INIS)

    Lai Shigang; Sun Libin; Zhang Zhengming

    2013-01-01

    Background: Reactors with graphite core structure include production reactor, water-cooled graphite reactor, gas-cooled reactor, high-temperature gas-cooled reactor and so on. Multi-body graphite core structure has nonlinear response under seismic excitation, which is different from the response of general civil structure, metal connection structure or bolted structure. Purpose: In order to provide references for the designing and construction of HTR-PM. This paper reviews the history of reactor seismic research evaluation from certain countries, and summarizes the research methods and research results. Methods: By comparing the methods adopted in different gas-cooled reactor cores, inspiration for our own HTR seismic research was achieved. Results and Conclusions: In this paper, the research ideas of graphite core seismic during the process of designing, constructing and operating HTR-10 are expounded. Also the project progress of HTR-PM and the research on side reflection with the theory of similarity is introduced. (authors)

  5. Review: BNL Tokamak graphite blanket design concepts

    International Nuclear Information System (INIS)

    Fillo, J.A.; Powell, J.R.

    1976-01-01

    The BNL minimum activity graphite blanket designs are reviewed, and three are discussed in the context of an experimental power reactor (EPR) and commercial power reactor. Basically, the three designs employ a 30 cm or thicker graphite screen. Bremsstrahlung energy is deposited on the graphite surface and re-radiated away as thermal radiation. Fast neutrons are slowed down in the graphite, depositing most of their energy, which is then radiated to a secondary blanket with coolant tubes, as in types A and B, or removed by intermittent direct gas cooling (type C). In types A and B, radiation damage to the coolant tubes in the secondary blanket is reduced by one or two orders of magnitude, while in type C, the blanket is only cooled when the reactor is shut down, so that coolant cannot quench the plasma. (Auth.)

  6. Immobilization of Rocky Flats Graphite Fines Residue

    International Nuclear Information System (INIS)

    Rudisill, T.S.

    1999-01-01

    The development of the immobilization process for graphite fines has proceeded through a series of experimental programs. The experimental procedures and results from each series of experiments are discussed in this report

  7. Optical motion control of maglev graphite.

    Science.gov (United States)

    Kobayashi, Masayuki; Abe, Jiro

    2012-12-26

    Graphite has been known as a typical diamagnetic material and can be levitated in the strong magnetic field. Here we show that the magnetically levitating pyrolytic graphite can be moved in the arbitrary place by simple photoirradiation. It is notable that the optical motion control system described in this paper requires only NdFeB permanent magnets and light source. The optical movement is driven by photothermally induced changes in the magnetic susceptibility of the graphite. Moreover, we demonstrate that light energy can be converted into rotational kinetic energy by means of the photothermal property. We find that the levitating graphite disk rotates at over 200 rpm under the sunlight, making it possible to develop a new class of light energy conversion system.

  8. Study on graphite samples for nuclear usage

    International Nuclear Information System (INIS)

    Suarez, J.C.M.; Silva Roseira, M. da

    1994-01-01

    Available as short communication only. The graphite, due to its properties (mechanical strength, thermal conductivity, high-temperature stability, machinability etc.) have many industrial applications, and consequently, an important strategic value. In the nuclear area, it has been used as moderator and reflector of neutrons in the fission process of uranium. The graphite can be produced from many types of carbonaceous materials by a variety of process dominated by the manufactures. This is the reason why there are in the world market a lot of graphite types with different physical and mechanical properties. The present investigation studies some physical characteristics of the graphite samples destined to use in a nuclear reactor. (author). 8 refs, 1 fig, 1 tab

  9. Collective modes in superconducting rhombohedral graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kauppila, Ville [O.V. Lounasmaa Laboratory, Aalto University (Finland); Hyart, Timo; Heikkilae, Tero [University of Jyvaeskylae (Finland)

    2015-07-01

    Recently it was realized that coupling particles with a Dirac dispersion (such as electrons in graphene) can lead to a topologically protected state with flat band dispersion. Such a state could support superconductivity with unusually high critical temperatures. Perhaps the most promising way to realize such coupling in real materials is in the surface of rhombohedrally stacked graphite. We consider collective excitations (i.e. the Higgs modes) in surface superconducting rhombohedral graphite. We find two amplitude and two phase modes corresponding to the two surfaces of the graphite where the superconductivity lives. We calculate the dispersion of these modes. We also derive the Ginzburg-Landau theory for this material. We show that in superconducting rhombohedral graphite, the collective modes, unlike in conventional BCS superconductors, give a large contribution to thermodynamic properties of the material.

  10. Large Scale Reduction of Graphite Oxide

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to develop an optical method to reduce graphite oxide into graphene efficiently and in larger formats than currently available. Current reduction...

  11. Analysis of picosecond pulsed laser melted graphite

    International Nuclear Information System (INIS)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M.S.; Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N.

    1986-01-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm -1 and the disorder-induced mode at 1360 cm -1 , the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nonosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence

  12. Vapour pressure of caesium over nuclear graphite

    International Nuclear Information System (INIS)

    Faircloth, R.L.; Pummery, F.C.W.

    1976-01-01

    The vapour pressure of caesium over a fine-grained isotropic moulded gilsocarbon nuclear graphite intended for use in the manufacture of fuel tubes for the high temperature reactor has been determined as a function of temperature and concentration by means of the Knudsen effusion technique. The concentration range 0 to 10 μg caesium/g graphite was investigated and it was concluded that a Langmuir adsorption situation exists under these conditions. (author)

  13. Elastic properties of graphite and interstitial defects

    International Nuclear Information System (INIS)

    Ayasse, J.-B.

    1977-01-01

    The graphite elastic constants C 33 and C 44 , reflecting the interaction of the graphitic planes, were experimentally measured as a function of irradiation and temperature. A model of non-central strength atomic interaction was established to explain the experimental results obtained. This model is valid at zero temperature. The temperature dependence of the elastic properties was analyzed. The influence of the elastic property variations on the specific heat of the lattice at very low temperature was investigated [fr

  14. Energy evaluations, graphite corrosion in Bugey I

    International Nuclear Information System (INIS)

    Brisbois, J.; Fiche, C.

    1967-01-01

    Bugey I presents a problem of radiolytic corrosion of the graphite by the CO 2 under pressure at high temperature. This report aims to evaluate the energy transferred to the gas by a Bugey I core cell, in normal operating conditions. The water, the carbon oxides and the hydrogen formed quantities are deduced as the consumed graphite and methane. Experimental studies are realized in parallel to validate the presented results. (A.L.B.)

  15. Graphene nanosheets and graphite oxide as promising adsorbents for removal of organic contaminants from aqueous solution.

    Science.gov (United States)

    Ji, Liangliang; Chen, Wei; Xu, Zhaoyi; Zheng, Shourong; Zhu, Dongqiang

    2013-01-01

    Graphenes are an emerging class of carbon nanomaterials whose adsorption properties toward organic compounds have not been well understood. In the present study, graphene nanosheets were prepared by reoxidation and abrupt heating of graphite oxide, which was prepared by sequential chemical oxidation of commercial nonporous graphite powder. Adsorption properties of three aromatic compounds (naphthalene, 2-naphthol, and 1-naphthylamine) and one pharmaceutical compound (tylosin) on graphene nanosheets and graphite oxide were examined to explore the potential of these two adsorbents for the removal of organic contaminants from aqueous solutions. Compared with the literature data of adsorption on carbon nanotubes, adsorption of bulky, flexible tylosin on graphene nanosheets exhibited markedly faster adsorption kinetics, which can be attributed to their opened-up layer structure. Graphene nanosheets and graphite oxide showed similar sequences of adsorption affinity: 1-naphthylamine > 2-naphthol > tylosin > naphthalene (with much larger differences observed on graphite oxide). It was proposed that the strong adsorption of the three aromatic compounds was mainly due to π-π electron donor-acceptor interactions with the graphitic surfaces of adsorbents. Additionally, Lewis acid-base interaction was likely an important factor contributing to the strong adsorption of 1-naphthylamine and tylosin, especially for the O-functionality-abundant graphite oxide. After being normalized on the basis of adsorbent surface area, adsorption affinities of all four tested adsorbates on graphene nanosheets were very close to those on nonporous graphite powder, reflecting complete accessibility of the adsorbent surface area in adsorption. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  16. Leveraging comprehensive baseline datasets to quantify property variability in nuclear-grade graphites

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Mark C., E-mail: mark.carroll@inl.gov [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-2213 (United States); Windes, William E.; Rohrbaugh, David T. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-2213 (United States); Strizak, Joseph P.; Burchell, Timothy D. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6088 (United States)

    2016-10-15

    Highlights: • An effort is underway to fully quantify the properties of nuclear-grade graphites. • Physical and mechanical properties of graphite are best characterized by distributions. • The Weibull distribution is most representative of graphite based on goodness-of-fit. • Fine-grained isomolded grades exhibit higher Weibull modulus values, indicative of more homogeneous properties. - Abstract: The full characterization of the physical and mechanical properties of candidate nuclear-grade graphites is highly dependent upon an understanding of the distribution of values that are inherent to graphite. Not only do the material properties of graphites vary considerably between grades owing to the raw materials sources, filler particle type and size, methods of compaction, and production process parameters, but variability is observed between billets of the same grade from a single batch and even across spatial positions within a single billet. Properly enveloping the expected properties of interest requires both a substantial amount of data to statistically capture this variability and a representative distribution capable of accurately describing the range of values. A two-parameter Weibull distribution is confirmed to be representative of the distribution of physical (density, modulus) and mechanical (compressive, flexure, and tensile strength) values in five different nuclear-grades of graphite. The fine-grained isomolded grades tend toward higher Weibull modulus and characteristic strength values, while the extruded grade being examined exhibits relatively large distributions in property values. With the number of candidate graphite specimens that can undergo full irradiation exposure and subsequent testing having limited feasibility with regard to economics and timely evaluations, a proper capture of the raw material variability in an unirradiated state can provide crucial supplementary resolution to the limited amount of available data on irradiated

  17. Production of nanodiamonds by high-energy ion irradiation of graphite at room temperature

    International Nuclear Information System (INIS)

    Daulton, T.L.; Kirk, M.A.; Lewis, R.S.; Rehn, L.E.

    2001-01-01

    It has previously been shown that graphite can be transformed into diamond by MeV electron and ion irradiation at temperatures above approximately 600 deg. C. However, there exists geological evidence suggesting that carbonaceous materials can be transformed to diamond by irradiation at substantially lower temperatures. For example, submicron-size diamond aggregates have been found in uranium-rich, Precambrian carbonaceous deposits that never experienced high temperature or pressure. To test if diamonds can be formed at lower irradiation temperatures, sheets of fine-grain polycrystalline graphite were bombarded at 20 deg. C with 350±50 MeV Kr ions to fluences of 6x10 12 cm -2 using the Argonne tandem linear accelerator system (ATLAS). Ion-irradiated (and unirradiated control) graphite specimens were then subjected to acid dissolution treatments to remove untransformed graphite and isolate diamonds that were produced; these acid residues were subsequently characterized by high-resolution and analytical electron microscopy. The acid residue of the ion-irradiated graphite was found to contain nanodiamonds, demonstrating that ion irradiation of graphite at ambient temperature can produce diamond. The diamond yield under our irradiation conditions is low, ∼0.01 diamonds/ion. An important observation that emerges from comparing the present result with previous observations of diamond formation during irradiation is that nanodiamonds form under a surprisingly wide range of irradiation conditions. This propensity may be related to the very small difference in the graphite and diamond free-energies coupled with surface-energy considerations that may alter the relative stability of diamond and graphite at nanometer sizes

  18. Non-activated high surface area expanded graphite oxide for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Vermisoglou, E.C.; Giannakopoulou, T.; Romanos, G.E.; Boukos, N.; Giannouri, M. [Institute of Nanoscience and Nanotechnology “Demokritos”, 153 43 Ag. Paraskevi, Attikis (Greece); Lei, C.; Lekakou, C. [Division of Mechanical, Medical, and Aerospace Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Trapalis, C., E-mail: c.trapalis@inn.demokritos.gr [Institute of Nanoscience and Nanotechnology “Demokritos”, 153 43 Ag. Paraskevi, Attikis (Greece)

    2015-12-15

    Graphical abstract: - Highlights: • One-step exfoliation and reduction of graphite oxide via microwave irradiation. • Effect of pristine graphite (type, flake size) on the microwave expanded material. • Effect of pretreatment and oxidation cycles on the produced expanded material. • Expanded graphene materials with high BET surface areas (940 m{sup 2}/g–2490 m{sup 2}/g). • Non-activated graphene based materials suitable for supercapacitors. - Abstract: Microwave irradiation of graphite oxide constitutes a facile route toward production of reduced graphene oxide, since during this treatment both exfoliation and reduction of graphite oxide occurs. In this work, the effect of pristine graphite (type, size of flakes), pretreatment and oxidation cycles on the finally produced expanded material was examined. All the types of graphite that were tested afforded materials with high BET surface areas ranging from 940 m{sup 2}/g to 2490 m{sup 2}/g, without intervening an activation stage at elevated temperature. SEM and TEM images displayed exfoliated structures, where the flakes were significantly detached and curved. The quality of the reduced graphene oxide sheets was evidenced both by X-ray photoelectron spectroscopy and Raman spectroscopy. The electrode material capacitance was determined via electrochemical impedance spectroscopy and cyclic voltammetry. The materials with PEDOT binder had better performance (∼97 F/g) at low operation rates while those with PVDF binder performed better (∼20 F/g) at higher rates, opening up perspectives for their application in supercapacitors.

  19. The irradiation induced creep of graphite under accelerated damage produced by boron doping

    International Nuclear Information System (INIS)

    Brocklehurst, J.E.

    1975-01-01

    The presence of boron enhances fast neutron irradiation damage in graphite by providing nucleation sites for interstitial loop formation. Doping with 11 B casues an increase in the irradiation induced macroscopic dimensional changes, which have been shown to result from an acceleration in the differential crystal growth rate for a given carbon atom displacement rate. Models of irradiation induced creep in graphite have centred around those in which creep is induced by internal stresses due to the anisotopic crystal growth, and those in which creep is activated by atomic displacements. A creep test on boron doped graphite has been performed in an attempt to establish which of these mechanisms is the determining factor. An isotropic nuclear graphite was doped to a 11 B concentration of 0.27 wt.%. The irradiation induced volume shrinkage rate at 750 0 C increased by a factor of 3 over that of the virgin graphite, in agreement with predictions from the earlier work, but the total creep strains were comparable in both doped and virgin samples. This observation supports the view that irradiation induced creep is dependent only on the carbon atom displacement rate and not on the internal stress level determined by the differential crystal growth rate. The implications of this result on the irradiation behaviour of graphite containing significant concentrations of boron are briefly discussed. (author)

  20. Study on efficient methods for removal and treatment of graphite blocks in a gas cooled reactor

    International Nuclear Information System (INIS)

    Fujii, S.; Shirakawa, M.; Murakami, T.

    2001-01-01

    Tokai Power Station (GCR, 166 MWe) started its commercial operation on July 1966 and ceased activities at the end of March 1998 after 32 years of operation. The decommissioning plans are being developed, to prepare for near future dismantling. In the study, the methods for removal of the graphite blocks of about 1,600 ton have been developed to carrying it out safely and in a short period of time, and the methods of treatment of graphite have also been developed. All technological items have been identified for which R and D work will be required for removal from the core and treatment for disposal. (1) In order to reduce the programme required for the dismantling of reactor internals, an efficient method for removal of the graphite blocks is necessary. For this purpose the design of a dismantling machine has been investigated which can extract several blocks at a time. The conceptual design has being developed and the model has been manufactured and tested in a mock-up facility. (2) In order to reduce disposal costs, it will be necessary to segment the graphite blocks, maximising the packing density available in the disposal containers. Some of the graphite blocks will be cut into pieces longitudinally by a remote machine. Relevant technical matters have been identified, such as graphite cutting methods, the nature of fine particles arising from the cutting operation, the treatment of fine particles for disposal, and the method of mortar filling inside the waste container. (author)

  1. Graphite Composite Panel Polishing Fixture

    Science.gov (United States)

    Hagopian, John; Strojny, Carl; Budinoff, Jason

    2011-01-01

    The use of high-strength, lightweight composites for the fixture is the novel feature of this innovation. The main advantage is the light weight and high stiffness-to-mass ratio relative to aluminum. Meter-class optics require support during the grinding/polishing process with large tools. The use of aluminum as a polishing fixture is standard, with pitch providing a compliant layer to allow support without deformation. Unfortunately, with meter-scale optics, a meter-scale fixture weighs over 120 lb (.55 kg) and may distort the optics being fabricated by loading the mirror and/or tool used in fabrication. The use of composite structures that are lightweight yet stiff allows standard techniques to be used while providing for a decrease in fixture weight by almost 70 percent. Mounts classically used to support large mirrors during fabrication are especially heavy and difficult to handle. The mount must be especially stiff to avoid deformation during the optical fabrication process, where a very large and heavy lap often can distort the mount and optic being fabricated. If the optic is placed on top of the lapping tool, the weight of the optic and the fixture can distort the lap. Fixtures to support the mirror during fabrication are often very large plates of aluminum, often 2 in. (.5 cm) or more in thickness and weight upwards of 150 lb (68 kg). With the addition of a backing material such as pitch and the mirror itself, the assembly can often weigh over 250 lb (.113 kg) for a meter-class optic. This innovation is the use of a lightweight graphite panel with an aluminum honeycomb core for use as the polishing fixture. These materials have been used in the aerospace industry as structural members due to their light weight and high stiffness. The grinding polishing fixture consists of the graphite composite panel, fittings, and fixtures to allow interface to the polishing machine, and introduction of pitch buttons to support the optic under fabrication. In its

  2. The impacts of moisture transport on drifting snow sublimation in the saltation layer

    Directory of Open Access Journals (Sweden)

    N. Huang

    2016-06-01

    Full Text Available Drifting snow sublimation (DSS is an important physical process related to moisture and heat transfer that happens in the atmospheric boundary layer, which is of glaciological and hydrological importance. It is also essential in order to understand the mass balance of the Antarctic ice sheets and the global climate system. Previous studies mainly focused on the DSS of suspended snow and ignored that in the saltation layer. Here, a drifting snow model combined with balance equations for heat and moisture is established to simulate the physical DSS process in the saltation layer. The simulated results show that DSS can strongly increase humidity and cooling effects, which in turn can significantly reduce DSS in the saltation layer. However, effective moisture transport can dramatically weaken the feedback effects. Due to moisture advection, DSS rate in the saltation layer can be several orders of magnitude greater than that of the suspended particles. Thus, DSS in the saltation layer has an important influence on the distribution and mass–energy balance of snow cover.

  3. ZnO sublimation using a polyenergetic pulsed electron beam source: numerical simulation and validation

    Energy Technology Data Exchange (ETDEWEB)

    Tricot, S; Semmar, N; Lebbah, L; Boulmer-Leborgne, C, E-mail: sylvain.tricot@univ-orleans.f [GREMI, UMR 6606-CNRS/Universite d' Orleans, 14 rue d' Issoudun, BP 6744, 45067 Orleans cedex 2 (France)

    2010-02-17

    This paper details the electro-thermal study of the sublimation phase on a zinc oxide surface. This thermodynamic process occurs when a ZnO target is bombarded by a pulsed electron beam source composed of polyenergetic electrons. The source delivers short pulses of 180 ns of electrons with energies up to 16 keV. The beam total current reaches 800 A and is focused onto a spot area 2 mm in diameter. The Monte Carlo CASINO program is used to study the first stage of the interaction and to define the heat source space distribution inside the ZnO target. Simulation of the second stage of interaction is developed in a COMSOL multiphysics project. The simulated thermal field induced by space and time heat conduction is presented. Typically for a pulsed electron beam 2 mm in diameter of electrons having energies up to 16 keV, the surface temperature reaches a maximum of 7000 K. The calculations are supported by SEM pictures of the target irradiated by various beam energies and numbers of pulses.

  4. ZnO sublimation using a polyenergetic pulsed electron beam source: numerical simulation and validation

    International Nuclear Information System (INIS)

    Tricot, S; Semmar, N; Lebbah, L; Boulmer-Leborgne, C

    2010-01-01

    This paper details the electro-thermal study of the sublimation phase on a zinc oxide surface. This thermodynamic process occurs when a ZnO target is bombarded by a pulsed electron beam source composed of polyenergetic electrons. The source delivers short pulses of 180 ns of electrons with energies up to 16 keV. The beam total current reaches 800 A and is focused onto a spot area 2 mm in diameter. The Monte Carlo CASINO program is used to study the first stage of the interaction and to define the heat source space distribution inside the ZnO target. Simulation of the second stage of interaction is developed in a COMSOL multiphysics project. The simulated thermal field induced by space and time heat conduction is presented. Typically for a pulsed electron beam 2 mm in diameter of electrons having energies up to 16 keV, the surface temperature reaches a maximum of 7000 K. The calculations are supported by SEM pictures of the target irradiated by various beam energies and numbers of pulses.

  5. Thin film CdTe solar cells by close spaced sublimation: Recent results from pilot line

    International Nuclear Information System (INIS)

    Siepchen, B.; Drost, C.; Späth, B.; Krishnakumar, V.; Richter, H.; Harr, M.; Bossert, S.; Grimm, M.; Häfner, K.; Modes, T.; Zywitzki, O.; Morgner, H.

    2013-01-01

    CdTe is an attractive material to produce high efficient and low cost thin film solar cells. The semiconducting layers of this kind of solar cell can be deposited by the Close Spaced Sublimation (CSS) process. The advantages of this technique are high deposition rates and an excellent utilization of the raw material, leading to low production costs and competitive module prices. CTF Solar GmbH is offering equipment and process knowhow for the production of CdTe solar modules. For further improvement of the technology, research is done at a pilot line, which covers all relevant process steps for manufacture of CdTe solar cells. Herein, we present the latest results from the process development and our research activities on single functional layers as well as for complete solar cell devices. Efficiencies above 13% have already been obtained with Cu-free back contacts. An additional focus is set on different transparent conducting oxide materials for the front contact and a Sb 2 Te 3 based back contact. - Highlights: ► Laboratory established on industrial level for CdTe solar cell research ► 13.0% cell efficiency with our standard front contact and Cu-free back contact ► Research on ZnO-based transparent conducting oxide and Sb 2 Te 3 back contacts ► High resolution scanning electron microscopy analysis of ion polished cross section

  6. Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTs) Volume 5: Graphite PIRTs

    International Nuclear Information System (INIS)

    Burchell, Timothy D.; Bratton, Rob; Marsden, Barry; Srinivasan, Makuteswara; Penfield, Scott; Mitchell, Mark; Windes, Will

    2008-01-01

    ) concepts, such as the NGNP, it is fully expected that the behavior of these graphites will conform to the recognized trends for near isotropic nuclear graphite. Thus, much of the data needed is confirmatory in nature. Theories that can explain graphite behavior have been postulated and, in many cases, shown to represent experimental data well. However, these theories need to be tested against data for the new graphites and extended to higher neutron doses and temperatures pertinent to the new Gen IV reactor concepts. It is anticipated that current and planned future graphite irradiation experiments will provide the data needed to validate many of the currently accepted models, as well as providing the needed data for design confirmation

  7. Structure and functionality of bromine doped graphite.

    Science.gov (United States)

    Hamdan, Rashid; Kemper, A F; Cao, Chao; Cheng, H P

    2013-04-28

    First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br2). However, with increased compression (decreased layer-layer separation) Br2 molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br2 molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.

  8. Synthesis and Characterization of Highly Intercalated Graphite Bisulfate

    Science.gov (United States)

    Salvatore, Marcella; Carotenuto, Gianfranco; De Nicola, Sergio; Camerlingo, Carlo; Ambrogi, Veronica; Carfagna, Cosimo

    2017-03-01

    Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy ( μ-RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO4, K2Cr2O7) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO4 and NaClO3.

  9. Vapor pressure of plutonium carbide adsorbed on graphite

    International Nuclear Information System (INIS)

    Tallent, O.K.; Wichner, R.P.; Towns, R.L.; Godsey, T.T.

    1984-09-01

    An investigation was conducted to obtain data needed to make realistic estimates of plutonium contamination in the primary coolant system in High Temperature Gas-Cooled Reactors (HTGRs). The vapor pressure of plutonium over plutonium sesquicarbide (Pu 2 C 3 ) adsorbed on the surface of H-451 graphite was found to be defined by adsorption isotherms at test temperatures of 1000, 1200, and 1400 0 C. The vapor pressures at low concentrations of Pu 2 C 3 on the surface of the graphite were up to three orders of magnitude below that of pure Pu 2 C 3 at a given temperature. The heat of adsorption increases with decreasing Pu 2 C 3 surface coverage with the measured value at 0.05 μmol Pu 2 C 3 /m 2 being 107.9 kcal/mol. The Pu 2 C 3 concentration required for monolayer surface coverage on the graphite was found to be 3.27 μmol/m 2

  10. Mechanical and thermophysical properties of graphite/polyimide composite materials

    Science.gov (United States)

    Rummler, D. R.; Clark, R. K.

    1979-01-01

    An on-going program to characterize advanced composites for up to 50,000 hours of exposure to simulated supersonic cruise environments is summarized. Results are presented for up to 25,000 hours of thermal exposure and 10,000 hours of flight simulation at temperatures up to 560K (550 F) with emphasis on HTS/710 graphite/polyimide composite material. Results to date indicate that the maximum use temperature for HTS/710 may be reduced to 505K (450 F) for long-time (1000 hours) application such as the supersonic transport. Preliminary thermophysical properties data for HTS/PMR15 graphite/polyimide were generated. These data include thermal conductivity, thermal expansion, and specific heat from 115K (-252 F) to 590K (600 F) and emittance at room temperature and 590K (600 F). The purpose in generating these data was to validate use of state-of-the-art property measurement methods for advanced graphite fiber reinforced resin matrix composites. Based on results to this point, thermal expansion measurements for composites are most difficult to perform. A high degree of caution in conducting thermal expansion tests and analyzing results is required to produce reliable data.

  11. Investigation on structural integrity of graphite component during high temperature 950degC continuous operation of HTTR

    International Nuclear Information System (INIS)

    Sumita, Junya; Shimazaki, Yosuke; Shibata, Taiju

    2014-01-01

    Graphite material is used for internal structures in high temperature gas-cooled reactor. The core components and graphite core support structures are so designed as to maintain the structural integrity to keep core cooling capability. To confirm that the core components and graphite core support structures satisfy the design requirements, the temperatures of the reactor internals are measured during the reactor operation. Surveillance test of graphite specimens and in-service inspection using TV camera are planned in conjunction with the refueling. This paper describes the evaluation results of the integrity of the core components and graphite core support structures during the high temperature 950degC continuous operation, a high temperature continuous operation with reactor outlet temperature of 950degC for 50 days, in high temperature engineering test reactor. The design requirements of the core components and graphite core support structures were satisfied during the high temperature 950degC continuous operation. The dimensional change of graphite which directly influences the temperature of coolant was estimated considering the temperature profiles of fuel block. The magnitude of irradiation-induced dimensional change considering temperature profiles was about 1.2 times larger than that under constant irradiation temperature of 1000degC. In addition, the programs of surveillance test and ISI using TV camera were introduced. (author)

  12. Improved techniques for the ultrasonic characterization of graphite

    International Nuclear Information System (INIS)

    Cook, K.V.; Simpson, W.A.

    1981-01-01

    Near-conventional pulse-echo flaw detection techniques can be successfully applied to graphite material. If the specimen configuration (i.e., length-to-diameter ratio) is conducive to the choice of ultrasonic test parameters dictated by the material screening tests, then only the test sensitivity needs to be established. Conventional test block approaches to calibration work well; however, uniform homogeneity of the specimens to be tested must be assumed (depending on the graphite, this may be an invalid assumption). Sensitivities that we have demonstrated typically detect 0.5- to 0.75-mm (0.020 to 0.030-in.) reflectors at depths up to 102 mm (4 in.) for GRAPHNOL (drilled holes, not flat bottom). Other materials may dictate inspection for much larger discontinuities. The least sensitive tests performed to date (using the storage oscilloscope approach) required flat-bottom holes of 6.35 mm (0.250 in.) in diameter for calibration. This relatively insensitive test was necessary because of the billet length and material characteristics

  13. An examination of the thermodynamics of fusion, vaporization, and sublimation of ibuprofen and naproxen by correlation gas chromatography.

    Science.gov (United States)

    Maxwell, Rachel; Chickos, James

    2012-02-01

    The vaporization enthalpies of (S)-ibuprofen and (S)-naproxen measured by correlation gas chromatography at T = 298.15 K are reported and compared with literature values. Adjustment of the fusion enthalpies of (RS)- and (S)-ibuprofen and (S)-naproxen to T = 298.15 K and combined with the vaporization enthalpy of the (S)-enantiomer of both ibuprofen and naproxen also at T = 298.15 K resulted in the sublimation enthalpies of both (S)-enantiomers. On the assumption that the vaporization enthalpy of the racemic form of ibuprofen is within the experimental uncertainty of the chiral form, the sublimation enthalpy of racemic ibuprofen was also evaluated. The vaporization and sublimation enthalpies compare favorably to the most of the literature values for the racemic form of ibuprofen but differ from the value reported for chiral ibuprofen. The literature values of (S)-naproxen are somewhat smaller than the values measured in this work. The following vaporization enthalpies were measured for (S)-ibuprofen and (S)-naproxen, respectively: ΔH(vap) (298.15 K), 106.0 ± 5.5, 132.2 ± 5.0 kJ·mol(-1) . Sublimation enthalpies of 122.7 ± 5.6 and 155.2 ± 7.1 kJ·mol(-1) were calculated for the (S)-enantiomers of ibuprofen and naproxen and a value of 128.9 ± 5.8 kJ·mol(-1) was estimated for the racemic form of ibuprofen. Copyright © 2011 Wiley Periodicals, Inc.

  14. Developments in natural uranium - graphite reactors

    International Nuclear Information System (INIS)

    Bourgeois, J.

    1964-01-01

    The French natural uranium-graphite power-reactor programme has been developing - from EDF 1 to EDF 4 - in the direction of an increase of the unit power of the installations, of the specific and volume powers, and of an improvement in the operational security conditions. The high power of EDF 4 (500 MWe) and the integration of the primary circuit into the reactor vessel, which is itself made of pre-stressed concrete, make it possible to make the most of the annular fuel elements already in use in EDF 1, and to arrive thus at a very satisfactory solution. The use of an internally cooled fuel element (an annular element) has led to a further step forward: it now becomes possible to increase the pressure of the cooling gas without danger of causing creep in the uranium tube. The use of a pre-stressed concrete vessel makes this pressure increase possible, and the integration of the primary circuit avoids the risk of a rapid depressurization which would be in this case a major danger. This report deals with the main problems presented by this new type of nuclear power station, and gives the main lines of research and studies now being carried out in France. - Neutronic and thermal research has made it possible to consider using large size fuel elements (internal diameter = 77 mm, external diameter 95 mm) while still using natural uranium. - The problems connected with the production of these elements and with their in pile behaviour are the subject of a large programme, both out of pile and in power reactors (EDF 2) and test reactors (Pegase). - The increase in the size of the element leads to a large lattice pitch (35 to 40 cm). This makes it possible to consider having one charging aperture per channel or for a small number of channels, whether the charge machine be inside or outside the pressure vessel. In conclusion are given the main characteristics of a project for a 500 MWe power station using such a fuel element. In particular this project is compared to EDF 4

  15. Statistics of fracture in two grades of isotropic graphite

    International Nuclear Information System (INIS)

    Kennedy, C.R.; Montgomery, S.C.

    1990-01-01

    Properties in large billets of graphite used in critical applications demand a high level of quality assurance. Therefore, it must be determined if sample test results represent the properties of the entire billet. Flexure tests were performed on specimens from 27 populations in each grade with respect to billet, position, and orientation to establish the confidence levels for estimation of overall variance and mean strength in the billet. Comparisons of tensile and brittle ring to flexure strengths were made. Homogeneity of variance was found to be a tenable hypothesis; however, estimates of the billet mean strength were not as confidently predicted by the samples. (orig.)

  16. Statistics of fracture in two grades of isotropic graphite

    Science.gov (United States)

    Kennedy, C. R.; Montgomery, S. C.

    1990-04-01

    Properties in large billets of graphite used in critical applications demand a high level of quality assurance. Therefore, it must be determined if sample test results represent the properties of the entire billet. Flexure tests were performed on specimens from 27 populations in each grade with respect to billet, position, and orientation to establish the confidence levels for estimation of overall variance and mean strength in the billet. Comparisons of tensile and brittle ring to flexure strengths were made. Homogeneity of variance was found to be a tenable hypothesis; however, estimates of the billet mean strength were not as confidently predicted by the samples.

  17. An examination of the thermodynamics of fusion, vaporization, and sublimation of several parabens by correlation gas chromatography.

    Science.gov (United States)

    Umnahanant, Patamaporn; Chickos, James

    2011-05-01

    The vaporization, fusion, and sublimation enthalpies of methyl, ethyl, propyl, and butyl paraben are reported and compared with literature values. The vaporization enthalpies were measured by correlation gas chromatography and the fusion enthalpies by differential scanning calorimetry. Adjusted to T = 298.15 K, these enthalpies were combined to yield the sublimation enthalpy. The results compare favorably to some of the literature values but do not support the reversal in magnitude of both the vaporization and sublimation enthalpy previously reported for propyl and butyl paraben. The following fusion and vaporization enthalpies were measured for methyl through to butyl paraben, respectively: ΔH(fus) (T(fus) ) 26.3 ± 0.1 (398.6 K), 26.5 ± 0.1 (388.5 K), 27.3 ± 0.1 (368.8), and 25.9 ± 0.3 (340.7 K) kJ·mol(-1); ΔH(vap) (298.15 K) 79.5 ± 0.5, 84.0 ± 0.5, 89.7 ± 0.6, and 95.8 ± 0.6 kJ·mol(-1). The results are believed to be accurate to ± 4 kJ·mol(-1). Copyright © 2011 Wiley-Liss, Inc.

  18. Control and calculation of the titanium sublimation pumping speed and re-ionisation in the MAST neutral beam injectors

    International Nuclear Information System (INIS)

    McAdams, R.

    2015-01-01

    Highlights: • The titanium sublimation pumps for the MAST neutral beam injectors are described. • Evaporation regimes are established to give constant pumping speed for the titanium sublimation pumps. • The MCNP code is used to calculate the pumping speeds and gas profiles in the neutral beam injectors. • The gas profiles are then used to calculate the level of re-ionisation in the beamline. - Abstract: A high pumping speed is required in neutral beam injectors to minimise re-ionisation of the neutral beams. The neutral beam injectors on MAST use titanium sublimation pumps. These pumps do not have a constant pumping speed; their pumping speed depends on the gettering surface history and on both the integrated and applied gas load. In this paper we describe a method of maintaining a constant pumping speed, through different evaporation schemes, specifically suitable for operations of the MAST neutral beam injector beamlines for both short and relatively long beam pulses by measurement of the pressure in the beamline. In addition the MCNP code is then used to calculate the pumping speed and gas profile in the beamline by adjusting the input pumping speed to match the measured pressure. This allows the resulting gas profile to be used for calculation of the re-ionisation levels and an example is given

  19. Surface studies on graphite furnace platforms covered with Pd, Rh and Ir as modifiers in graphite furnace atomic absorption spectrometry of tellurium

    Energy Technology Data Exchange (ETDEWEB)

    Pedro, Juana [Area de Química Analítica, Departamento de Química, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829 (S3000GL.N), Santa Fe (Argentina); Stripekis, Jorge [Laboratorio de Análisis de Trazas, Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria (1428), Buenos Aires (Argentina); Departamento de Ingeniería Química, Instituto Tecnológico de Buenos Aires, Av. Eduardo Madero 399 (1106), Buenos Aires (Argentina); Bonivardi, Adrian [Area de Química Analítica, Departamento de Química, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829 (S3000GL.N), Santa Fe (Argentina); Tudino, Mabel, E-mail: tudino@qi.fcen.uba.ar [Laboratorio de Análisis de Trazas, Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria (1428), Buenos Aires (Argentina)

    2015-05-01

    The main objective of this work is the study of correlations between the efficiency of the distribution of the permanent platinum group modifiers Pd, Rh and Ir over the graphite surface with the aim of improving analytical signal of tellurium. Modifier solution was deposited onto the platform and pyrolysed after drying. In the case of Pd, the physical vaporization/deposition technique was also tested. In order to analyze the differences amongst coverings (morphology, topology and distribution), the graphite surfaces were studied with scanning electron microscopy and energy dispersive X-ray microscopy. Micrographs for physical vaporization and pyrolytic deposition of Pd were also analyzed in order to explain the lack of signal obtained for tellurium with the first alternative. Similar micrographs were obtained for pyrolytic deposition of Ir and Rh and then, compared to those of Pd. Ir showed the most homogeneous distribution on the graphite surface and the tallest and sharpest transient. With the aim of improving the analytical signal of tellurium, the correlation between the surface studies and the tellurium transient signal (height, area and shape) is discussed. - Highlights: • Distribution of Rh, Pd and Ir onto graphite furnaces is evaluated by SEM and EDX • Micrographs and spectra showed that surface distribution could influence Te signal. • Ir showed the best signal together with the most homogeneous surface distribution. • Pd-PVD micrographs revealed the absence of graphite and no signal for Te.

  20. On the development of standardization methods for measuring the degree of graphitization of industrial materials, correlation of scientific characterization with the industrially relevant secondary properties of graphitic material

    International Nuclear Information System (INIS)

    Fitzer, E.; Koechling, K.H.

    1984-01-01

    The completed research roject comprised the development of standardization methods for measuring the degree of graphitization of industrial materials, the testing of characterization methods with regard to significance, the correlation of scientific characterization with industrially relevant material properties and the resultant modification of industrial processes for the manufacture of coke raw materials and graphitic materials. Also targeted within the scope of this project were the grouping of comparable characterization methods and the drawing up of unequivocal terminology for scientific and industrial-commercial usage, with both aims based on intensified national and international teamwork. (orig./WL) [de

  1. Production of nuclear graphite in France; Production de graphite nucleaire en France

    Energy Technology Data Exchange (ETDEWEB)

    Legendre, P; Mondet, L [Societe Pechiney, 74 - Chedde (France); Arragon, Ph; Cornuault, P; Gueron, J; Hering, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    The graphite intended for the construction of the reactors is obtained by the usual process: confection of a cake from coke of oil and tar, cooked (in a electric oven) then the product of cook is graphitized, also by electric heating. The use of the air transportation and the control of conditions cooking and graphitization have permitted to increase the nuclear graphite production as well as to better control their physical and mechanical properties and to reduce to the minimum the unwanted stains. (M.B.) [French] Le graphite destine a la construction des reacteurs est obtenu par le procede usuel: confection d'une pate a partir de coke de petrole et de brai, cuisson de cette pate (au four electrique) puis graphitation du produit cuit, egalement par chauffage electrique. L'usage du transport pneumatique et le controle des conditions cuisson et de graphitation ont permit d'augmenter la production de graphite nucleaire ainsi que de mieux controler ses proprietes physiques et mecaniques et de reduire au minimum les souillures accidentelles. (M.B.)

  2. Temperature distribution in graphite during annealing in air cooled reactors

    International Nuclear Information System (INIS)

    Oliveira Avila, C.R. de.

    1989-01-01

    A model for the evaluation temperature distributions in graphite during annealing operation in graphite. Moderated an-cooled reactors, is presented. One single channel and one dimension for air and graphite were considered. A numerical method based on finite control volumes was used for partioning the mathematical equations. The problem solution involves the use of unsteady equations of mass, momentum and energy conservation for air, and energy conservation for graphite. The source term was considered as stored energy release during annealing for describing energy conservation in the graphite. The coupling of energy conservation equations in air and graphite is performed by the heat transfer term betwen air and graphite. The results agree with experimental data. A sensitivity analysis shown that the termal conductivity of graphite and the maximum inlet channel temperature have great effect on the maximum temperature reached in graphite during the annealing. (author)

  3. Study on thermal conductivity of HTR spherical fuel element matrix graphite

    International Nuclear Information System (INIS)

    Zhang Kaihong; Liu Xiaoxue; Zhao Hongsheng; Li Ziqiang; Tang Chunhe

    2014-01-01

    Taking the spherical fuel element matrix graphite ball samples as an example, this paper introduced the principle and method of laser thermal conductivity meter, as well as the specific heat capacity, and analyzed the effects of different test methods and sampling methods on the thermal conductivities at 1000 ℃ of graphite material. The experimental results show that the thermal conductivities of graphite materials tested by synchronous thermal analyzer combining with laser thermal conductivity meter were different from that directly by laser thermal conductivity meter, the former was more reliable and accurate than the later; When sampling from different positions, central samples had higher thermal conductivities than edging samples, which was related to the material density and porosity at the different locations; the thermal conductivities had obvious distinction between samples from different directions, which was because the layer structure of polycrystalline graphite preferred orientation under pressure, generally speaking, the thermal conductivities perpendicular to the molding direction were higher than that parallel to the molding direction. Besides this, the test results show that the thermal conductivities of all the graphite material samples were greater than 30 W/(m (K), achieving the thermal performance index of high temperature gas cooled reactor. (authors)

  4. A Simulation Model for Tensile Fracture Procedure Analysis of Graphite Material based on Damage Evolution

    International Nuclear Information System (INIS)

    Zhao Erqiang; Ma Shaopeng; Wang Hongtao

    2014-01-01

    Graphite material is generally easy to be damaged by the widely distributed micro-cracks when subjects to load. For numerically analyzing of the structure made of graphite material, the influences of the degradation of the material in damaged areas need to be considered. In this paper, an axial tension test method is proposed to obtain the dynamic damage evolution rule of the material. Using the degradation rule (variation of elastic modulus), the finite element model is then constructed to analyze the tensile fracture process of the L-shaped graphite specimen. An axial tension test of graphite is performed to obtain the stress-strain curve. Based on the variation of the measured curve, the damage evolution rule of the material are fitted out. A simulation model based on the above measured results is then constructed on ABAQUS by user subroutine. Using this simulation model, the tension failure process of L-shaped graphite specimen with fillet are simulated. The calculated and experimental results on fracture load are in good agreement. The damage simulation model based on the stress-strain curve of axial tensile test can be used in other tensile fracture analysis. (author)

  5. Graphite matrix materials for nuclear waste isolation

    International Nuclear Information System (INIS)

    Morgan, W.C.

    1981-06-01

    At low temperatures, graphites are chemically inert to all but the strongest oxidizing agents. The raw materials from which artificial graphites are produced are plentiful and inexpensive. Morover, the physical properties of artificial graphites can be varied over a very wide range by the choice of raw materials and manufacturing processes. Manufacturing processes are reviewed herein, with primary emphasis on those processes which might be used to produce a graphite matrix for the waste forms. The approach, recommended herein, involves the low-temperature compaction of a finely ground powder produced from graphitized petroleum coke. The resultant compacts should have fairly good strength, low permeability to both liquids and gases, and anisotropic physical properties. In particular, the anisotropy of the thermal expansion coefficients and the thermal conductivity should be advantageous for this application. With two possible exceptions, the graphite matrix appears to be superior to the metal alloy matrices which have been recommended in prior studies. The two possible exceptions are the requirements on strength and permeability; both requirements will be strongly influenced by the containment design, including the choice of materials and the waste form, of the multibarrier package. Various methods for increasing the strength, and for decreasing the permeability of the matrix, are reviewed and discussed in the sections in Incorporation of Other Materials and Elimination of Porosity. However, it would be premature to recommend a particular process until the overall multi-barrier design is better defined. It is recommended that increased emphasis be placed on further development of the low-temperature compacted graphite matrix concept

  6. Method of producing exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z.

    2010-11-02

    The present invention provides a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of graphite, graphite oxide, or a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

  7. EEL Calculations and Measurements of Graphite and Graphitic-CNx Core-Losses

    International Nuclear Information System (INIS)

    Seepujak, A; Bangert, U; Harvey, A J; Blank, V D; Kulnitskiy, B A; Batov, D V

    2006-01-01

    Core EEL spectra of MWCNTs (multi-wall carbon nanotubes) grown in a nitrogen atmosphere were acquired utilising a dedicated STEM equipped with a Gatan Enfina system. Splitting of the carbon K-edge π* resonance into two peaks provided evidence of two nondegenerate carbon bonding states. In order to confirm the presence of a CN x bonding state, a full-potential linearised augmented plane-wave method was utilised to simulate core EEL spectra of graphite and graphitic-CN x compounds. The simulations confirmed splitting of the carbon K-edge π* resonance in graphitic-CN x materials, with the pristine graphite π* resonance remaining unsplit. The simulations also confirmed the increasing degree of amorphicity with higher concentrations (25%) of substitutional nitrogen in graphite

  8. Removal of 14C from Irradiated Graphite for Graphite Recycle and Waste Volume Reduction

    International Nuclear Information System (INIS)

    Dunzik-Gougar, Mary Lou; Windes, Will; Marsden, Barry

    2014-01-01

    The aim of the research presented here was to identify the chemical form of 14 C in irradiated graphite. A greater understanding of the chemical form of this longest-lived isotope in irradiated graphite will inform not only management of legacy waste, but also development of next generation gas-cooled reactors. Approximately 250,000 metric tons of irradiated graphite waste exists worldwide, with the largest single quantity originating in the Magnox and AGR reactors of UK. The waste quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation I gas-cooled, graphite moderated reactors. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 14 C, with a half-life of 5730 years.

  9. Meteorological conditions associated to high sublimation amounts in semiarid high-elevation Andes decrease the performance of empirical melt models

    Science.gov (United States)

    Ayala, Alvaro; Pellicciotti, Francesca; MacDonell, Shelley; McPhee, James; Burlando, Paolo

    2015-04-01

    Empirical melt (EM) models are often preferred to surface energy balance (SEB) models to calculate melt amounts of snow and ice in hydrological modelling of high-elevation catchments. The most common reasons to support this decision are that, in comparison to SEB models, EM models require lower levels of meteorological data, complexity and computational costs. However, EM models assume that melt can be characterized by means of a few index variables only, and their results strongly depend on the transferability in space and time of the calibrated empirical parameters. In addition, they are intrinsically limited in accounting for specific process components, the complexity of which cannot be easily reconciled with the empirical nature of the model. As an example of an EM model, in this study we use the Enhanced Temperature Index (ETI) model, which calculates melt amounts using air temperature and the shortwave radiation balance as index variables. We evaluate the performance of the ETI model on dry high-elevation sites where sublimation amounts - that are not explicitly accounted for the EM model - represent a relevant percentage of total ablation (1.1 to 8.7%). We analyse a data set of four Automatic Weather Stations (AWS), which were collected during the ablation season 2013-14, at elevations between 3466 and 4775 m asl, on the glaciers El Tapado, San Francisco, Bello and El Yeso, which are located in the semiarid Andes of central Chile. We complement our analysis using data from past studies in Juncal Norte Glacier (Chile) and Haut Glacier d'Arolla (Switzerland), during the ablation seasons 2008-09 and 2006, respectively. We use the results of a SEB model, applied to each study site, along the entire season, to calibrate the ETI model. The ETI model was not designed to calculate sublimation amounts, however, results show that their ability is low also to simulate melt amounts at sites where sublimation represents larger percentages of total ablation. In fact, we

  10. Characterization of the Sublimation and Vapor Pressure of 2-(2-Nitrovinyl) Furan (G-0) Using Thermogravimetric Analysis: Effects of Complexation with Cyclodextrins.

    Science.gov (United States)

    Ruz, Vivian; González, Mirtha Mayra; Winant, Danny; Rodríguez, Zenaida; Van den Mooter, Guy

    2015-08-19

    In the present work, the sublimation of crystalline solid 2-(2-nitrovinyl) furan (G-0) in the temperature range of 35 to 60 °C (below the melting point of the drug) was studied using thermogravimetric analysis (TGA). The sublimated product was characterized using Fourier-transformed-infrared spectroscopy (FT-IR) and thin layer chromatography (TLC). The sublimation rate at each temperature was obtained using the slope of the linear regression model and followed apparent zero-order kinetics. The sublimation enthalpy from 35 to 60 °C was obtained from the Eyring equation. The Gückel method was used to estimate the sublimation rate and vapor pressure at 25 °C. Physical mixtures, kneaded and freeze-dried complexes were prepared with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and sulfobutyl ether-β-cyclodextrin (SBE-β-CD) and analyzed using isothermal TGA at 50 °C. The complexation contributed to reducing the sublimation process. The best results were achieved using freeze-dried complexes with both cyclodextrins.

  11. Gas transport in graphitic materials

    International Nuclear Information System (INIS)

    Hoinkis, E.

    1995-02-01

    The characterization of the gas transport properties of porous solids is of interest in several fields of science and technology. Many catalysts, adsorbents, soils, graphites and carbons are porous. The gas transport through most porous solids can be well described by the dusty gas model invented by Evans, Watson and Mason. This model includes all modes of gas tranport under steady-state conditions, which are Knudsen diffusion, combined Knudsen/continuum diffusion and continuum diffusion, both for gas pairs with equal and different molecular weights. In the absence of a pressure difference gas transport in a pore system can be described by the combined Knudsen/continuum diffusion coefficient D 1 for component 1 in the pores, the Knudsen diffusion coefficient D 1K in the pores, and the continuum diffusion coefficient D 12 for a binary mixture in the pores. The resistance to stationary continuum diffusion of the pores is characterized by a geometrical factor (ε/τ) 12 = (ε/τ)D 12 , were D 12 is the continuum diffusion coefficient for a binary mixture in free space. The Wicke-Kallenbach method was often used to measure D 1 as function of pressure. D 12 and D 1K can be derived from a plot 1/D 1 νs P, and ε/τcan be calculated since D 12 is known. D 1K and the volume of dead end pores can be derived from transient measurements of the diffusional flux at low pressures. From D 1K the expression (ε/τ c ) anti l por may be calculated, which characterizes the pore system for molecular diffusion, where collisions with the pore walls are predominant. (orig.)

  12. Evaluation of brazing joint of graphites and molybdenum

    International Nuclear Information System (INIS)

    Ishiyama, Shintarou; Kodaira, Tsuneo; Oku, Tatsuo

    1991-01-01

    Bonding test of six kinds of graphites to molybdenum was performed in the following conditions: Brazing elements was obtained by mixing of titanium nickel and copper in the range of 90∼51w%, 40∼10w%, 31∼0w%, respectively. Nonpressed brazing was performed at maximum temperature 1,000degC in a vacuum. Strength tests of these brazed joints were done in the conditions of at high temperature up to, 1,100degC in a vacuum, after 200 heat cycles from room temperature to about 900degC. Optical observation were performed before and after electron beam tests at 3.0 kW/cm 2 ·0.1 s·5 shots. The following results were derived: (1) The good mixing condition was found for titanium, nickel and copper brazing material at 64, 23 and 13w%, respectively. (2) Bending strengths of the brazed joints at room temperature were found to be proportional to the bending strengths of the graphite. (3) Bending strengths of the brazed joints shows no change until tested temperature reached 900degC in a vacuum. (4) Bending strength of the brazed joints showed no change after 200 heat cycles in the temperature range of room ∼ about 900degC and the electron beam tests. (author)

  13. AdS/QCD, Light-Front Holography, and Sublimated Gluons

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    The gauge/gravity duality leads to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian - 'Light-Front Holography', which provides a Lorentz-invariant first-approximation to QCD, and successfully describes the spectroscopy of light-quark meson and baryons, their elastic and transition form factors, and other hadronic properties. The bound-state Schroedinger and Dirac equations of the soft-wall AdS/QCD model predict linear Regge trajectories which have the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. Light-front holography connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable {zeta} in 3+1 space at fixed light-front time. A key feature is the determination of the frame-independent light-front wavefunctions of hadrons - the relativistic analogs of the Schroedinger wavefunctions of atomic physics which allow one to compute form factors, transversity distributions, spin properties of the valence quarks, jet hadronization, and other hadronic observables. One thus obtains a one-parameter color-confining model for hadron physics at the amplitude level. AdS/QCD also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function with an infrared fixed point which agrees with the effective coupling a{sub g1} (Q{sup 2}) extracted from measurements of the Bjorken sum rule below Q{sup 2} < 1 GeV{sup 2}. This is consistent with a flux-tube interpretation of QCD where soft gluons with virtualities Q{sup 2} < 1 GeV{sup 2} are sublimated into a color-confining potential for quarks. We discuss a number of phenomenological hadronic properties which support this picture.

  14. Spectroscopic, microscopic, and internal stress analysis in cadmium telluride grown by close-space sublimation

    International Nuclear Information System (INIS)

    Manciu, Felicia S.; Salazar, Jessica G.; Diaz, Aryzbe; Quinones, Stella A.

    2015-01-01

    High quality materials with excellent ordered structure are needed for developing photovoltaic and infrared devices. With this end in mind, the results of our research prove the importance of a detailed, comprehensive spectroscopic and microscopic analysis in assessing cadmium telluride (CdTe) characteristics. The goal of this work is to examine not only material crystallinity and morphology, but also induced stress in the deposit material. A uniform, selective growth of polycrystalline CdTe by close-space sublimation on patterned Si(111) and Si(211) substrates is demonstrated by scanning electron microscopy images. Besides good crystallinity of the samples, as revealed by both Raman scattering and Fourier transform infrared absorption investigations, the far-infrared transmission data also show the presence of surface optical phonon modes, which is direct evidence of confinement in such a material. The qualitative identification of the induced stress was achieved by performing confocal Raman mapping microscopy on sample surfaces and by monitoring the existence of the rock-salt and zinc-blende structural phases of CdTe, which were associated with strained and unstrained morphologies, respectively. Although the induced stress in the material is still largely due to the high lattice mismatch between CdTe and the Si substrate, the current results provide a direct visualization of its partial release through the relaxation effect at crystallite boundaries and of preferential growth directions of less strain. Our study, thus offers significant value for improvement of material properties, by targeting the needed adjustments in the growth processes. - Highlights: • Assessing the characteristics of CdTe deposited on patterned Si substrates • Proving the utility of confocal Raman microscopy in monitoring the induced stress • Confirming the partial stress release through the grain boundary relaxation effect • Demonstrating the phonon confinement effect in low

  15. Analyses of hypothetical nuclear criticality excursions in 10- and 20-MW freezer/sublimer vessels

    International Nuclear Information System (INIS)

    Haught, C.F.; Jordan, W.C.; Basoglu, B.; Dodds, H.L.; Wilkinson, A.D.

    1995-01-01

    A theoretical model is used to predict the consequences of a postulated hypothetical nuclear criticality excursion in a freezer/sublimer (F/S). Previous work has shown that an intrusion of water into a F/S may result in a critical configuration. A first attempt is made to model the neutronic and thermal-hydraulic phenomena occurring during a criticality excursion involving both uranium hexafluoride (UF 6 ) and uranyl fluoride (UO 2 F 2 ) solution, which is present in the F/S during upset conditions. The model employs point neutronics coupled with simple thermal hydraulics. Reactivity feedback from changes in the properties of the system are included in the model. The excursion is studied in a 10-MW F/S with an initial load of 3,500 kg of 5% weight enriched UF 6 and in a 20-MW F/S with an initial load of 6,800 kg of 2% weight enriched UF 6 . The magnitude of the fission release determined in this work is 5.93 x 10 18 fissions in the 10-MW F/S and 4.21 x 10 18 fissions in the 20-MW F/S. In order to demonstrate the reliability of the techniques used in this work, a limited validation study was conducted by comparing the fission release and peak fission rate determined by this work with experimental results for a limited number of experiments. The agreement between calculations and experiments in the validation study is considered to be satisfactory. The calculational results for the hypothetical accidents in the two F/S vessels appear reasonable

  16. SUBLIMATION-DRIVEN ACTIVITY IN MAIN-BELT COMET 313P/GIBBS

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Henry H. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Hainaut, Olivier [European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching bei München (Germany); Novaković, Bojan [Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade (Serbia); Bolin, Bryce [Observatoire de la Côte d’Azur, Boulevard de l’Observatoire, B.P. 4229, F-06304 Nice Cedex 4 (France); Denneau, Larry; Haghighipour, Nader; Kleyna, Jan; Meech, Karen J.; Schunova, Eva; Wainscoat, Richard J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Fitzsimmons, Alan [Astrophysics Research Centre, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Kokotanekova, Rosita; Snodgrass, Colin [Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA (United Kingdom); Lacerda, Pedro [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Micheli, Marco [ESA SSA NEO Coordination Centre, Frascati, RM (Italy); Moskovitz, Nick; Wasserman, Lawrence [Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff, AZ 86001 (United States); Waszczak, Adam, E-mail: hhsieh@asiaa.sinica.edu.tw [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-02-10

    We present an observational and dynamical study of newly discovered main-belt comet 313P/Gibbs. We find that the object is clearly active both in observations obtained in 2014 and in precovery observations obtained in 2003 by the Sloan Digital Sky Survey, strongly suggesting that its activity is sublimation-driven. This conclusion is supported by a photometric analysis showing an increase in the total brightness of the comet over the 2014 observing period, and dust modeling results showing that the dust emission persists over at least three months during both active periods, where we find start dates for emission no later than 2003 July 24 ± 10 for the 2003 active period and 2014 July 28 ± 10 for the 2014 active period. From serendipitous observations by the Subaru Telescope in 2004 when the object was apparently inactive, we estimate that the nucleus has an absolute R-band magnitude of H{sub R} = 17.1 ± 0.3, corresponding to an effective nucleus radius of r{sub e} ∼ 1.00 ± 0.15 km. The object’s faintness at that time means we cannot rule out the presence of activity, and so this computed radius should be considered an upper limit. We find that 313P’s orbit is intrinsically chaotic, having a Lyapunov time of T{sub l} = 12,000 yr and being located near two three-body mean-motion resonances with Jupiter and Saturn, 11J-1S-5A and 10J+12S-7A, yet appears stable over >50 Myr in an apparent example of stable chaos. We furthermore find that 313P is the second main-belt comet, after P/2012 T1 (PANSTARRS), to belong to the ∼155 Myr old Lixiaohua asteroid family.

  17. Influence of Metal-Coated Graphite Powders on Microstructure and Properties of the Bronze-Matrix/Graphite Composites

    Science.gov (United States)

    Zhao, Jian-hua; Li, Pu; Tang, Qi; Zhang, Yan-qing; He, Jian-sheng; He, Ke

    2017-02-01

    In this study, the bronze-matrix/x-graphite (x = 0, 1, 3 and 5%) composites were fabricated by powder metallurgy route by using Cu-coated graphite, Ni-coated graphite and pure graphite, respectively. The microstructure, mechanical properties and corrosive behaviors of bronze/Cu-coated-graphite (BCG), bronze/Ni-coated-graphite (BNG) and bronze/pure-graphite (BPG) were characterized and investigated. Results show that the Cu-coated and Ni-coated graphite could definitely increase the bonding quality between the bronze matrix and graphite. In general, with the increase in graphite content in bronze-matrix/graphite composites, the friction coefficients, ultimate density and wear rates of BPG, BCG and BNG composites all went down. However, the Vickers microhardness of the BNG composite would increase as the graphite content increased, which was contrary to the BPG and BCG composites. When the graphite content was 3%, the friction coefficient of BNG composite was more stable than that of BCG and BPG composites, indicating that BNG composite had a better tribological performance than the others. Under all the values of applied loads (10, 20, 40 and 60N), the BCG and BNG composites exhibited a lower wear rate than BPG composite. What is more, the existence of nickel in graphite powders could effectively improve the corrosion resistance of the BNG composite.

  18. Detection of fatigue fracture in pearlitic flake graphite cast iron with the help of scanning and transmission electron microscopy

    International Nuclear Information System (INIS)

    Dunger, B.; Hunger, J.

    1976-01-01

    To prove the existence of the characteristic features of fatigue fracture in a pearlitic flake graphite cast iron, its fracture surface topography revealed by scanning electron microscopy has been compared with that of a pearlitic steel, the fractures having been caused by static tensile and by cyclic bending tests. The characteristic features of fatigue fracture were visible in the pearlitic matrix of the steel and of the flake graphite cast iron as well. These features differ characteristically from the lamellar structure of the pearlite, particularly after etching the surface area of the fractures. The graphite structures as viewed on the electron scanning and the electron transmission microscope are described. (orig.) [de

  19. Glassy carbon coated graphite for nuclear applications

    International Nuclear Information System (INIS)

    Delpeux S; Cacciaguerra T; Duclaux L

    2005-01-01

    Taking into account the problems caused by the treatment of nuclear wastes, the molten salts breeder reactors are expected to a great development. They use a molten fluorinated salt (mixture of LiF, BeF 2 , ThF 4 , and UF 4 ) as fuel and coolant. The reactor core, made of graphite, is used as a neutrons moderator. Despite of its compatibility with nuclear environment, it appears crucial to improve the stability and inertness of graphite against the diffusion of chemicals species leading to its corrosion. One way is to cover the graphite surface by a protective impermeable deposit made of glassy carbon obtained by the pyrolysis of phenolic resin or polyvinyl chloride precursors. The main difficulty in the synthesis of glassy carbon is to create exclusively, in the primary pyrolysis product, a micro-porosity of about twenty Angstroms which closes later at higher temperature. Therefore, the evacuation of the volatile products occurring mainly between 330 and 600 C, must progress slowly to avoid the material to crack. In this study, the optimal parameters for the synthesis of glassy carbon as well as glassy carbon deposits on nuclear-type graphite pieces are discussed. Both thermal treatment of phenolic and PVC resins have been performed. The structure and micro-texture of glassy carbon have been investigated by X-ray diffraction, scanning and transmission electron microscopies and helium pycno-metry. Glassy carbon samples (obtained at 1200 C) show densities ranging from 1.3 to 1.55 g/cm 3 and closed pores with nano-metric size (∼ 5 to 10 nm) appear clearly on the TEM micrographs. Then, a thermal treatment to 2700 C leads to the shrinkage of the entangled graphene ribbons, in good agreement with the proposed texture model for glassy carbon. Glassy carbon deposits on nuclear graphite have been developed by an impregnation method. The uniformity of the deposit depends clearly on the surface texture and the chemistry of the graphite substrate. The deposit regions where

  20. Glassy carbon coated graphite for nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Delpeux, S.; Cacciaguerra, T.; Duclaux, L. [Orleans Univ., CRMD, CNRS, 45 (France)

    2005-07-01

    Taking into account the problems caused by the treatment of nuclear wastes, the molten salts breeder reactors are expected to a great development. They use a molten fluorinated salt (mixture of LiF, BeF{sub 2}, ThF{sub 4}, and UF{sub 4}) as fuel and coolant. The reactor core, made of graphite, is used as a neutrons moderator. Despite of its compatibility with nuclear environment, it appears crucial to improve the stability and inertness of graphite against the diffusion of chemicals species leading to its corrosion. One way is to cover the graphite surface by a protective impermeable deposit made of glassy carbon obtained by the pyrolysis of phenolic resin [1,2] or polyvinyl chloride [3] precursors. The main difficulty in the synthesis of glassy carbon is to create exclusively, in the primary pyrolysis product, a micro-porosity of about twenty Angstroms which closes later at higher temperature. Therefore, the evacuation of the volatile products occurring mainly between 330 and 600 C, must progress slowly to avoid the material to crack. In this study, the optimal parameters for the synthesis of glassy carbon as well as glassy carbon deposits on nuclear-type graphite pieces are discussed. Both thermal treatment of phenolic and PVC resins have been performed. The structure and micro-texture of glassy carbon have been investigated by X-ray diffraction, scanning and transmission electron microscopies and helium pycno-metry. Glassy carbon samples (obtained at 1200 C) show densities ranging from 1.3 to 1.55 g/cm{sup 3} and closed pores with nano-metric size ({approx} 5 to 10 nm) appear clearly on the TEM micrographs. Then, a thermal treatment to 2700 C leads to the shrinkage of the entangled graphene ribbons (Fig 1), in good agreement with the proposed texture model for glassy carbon (Fig 2) [4]. Glassy carbon deposits on nuclear graphite have been developed by an impregnation method. The uniformity of the deposit depends clearly on the surface texture and the chemistry