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Sample records for temperature uf4 vapor

  1. Uranium isotope fractionation resulting from UF6 vapor distillation from containers

    International Nuclear Information System (INIS)

    Hedge, W.D.; Turner, C.M.

    1985-01-01

    This empirical study for possible isotopic fractionation due to UF 6 vapor distillation from valved containers was performed to determine the effects of repeated vapor sampling. Four different experiments were performed, each of which varied by the method of measuring the isotopic contents and/or by the difference in temperature gradients as follows: The ratio of the parent UF 6 to the desublimed UF 6 collected at liquid nitrogen temperature and homogenized was measured by sampling the containers. The ratio of the parent UF 6 to the desublimed UF 6 collected at liquid nitrogen temperature and homogenized was measured by direct comparison to each other without subsampling. The ratio of the parent UF 6 to the desublimed UF 6 collected at liquid nitrogen and ice-water temperatures and homogenized was measured by indirect comparison to a common UF 6 reference material without subsampling. The ratio of the parent UF 6 to the desublimed UF 6 collected at liquid nitrogen temperature without homogenizing was measured by indirect comparison to a common UF 6 reference. Gas-phase, relative mass spectrometry was used for all isotopic measurements. Results of the study indicate that fractionation does occur. The U-235 isotope becomes more enriched in the parent container as the UF 6 is vaporized from it and desublimed into the receiving cylinder; i.e., the vaporized fraction is enriched in the U-238 isotope. The degree of fractionation indicates that the separation is due to the U-238 isotope of UF 6 having a higher vapor pressure than the U-235 isotope of UF 6 . 3 refs., 4 figs., 4 tabs

  2. TENERIFE program: high temperature experiments on A 4 tons UF6 container

    International Nuclear Information System (INIS)

    Casselman, C.; Duret, B.; Seiler, J.M.; Ringot, C.; Warniez, P.; Wataru, M.; Shiomi, S.; Ozaki, S.; Yamakawa, H.

    1993-01-01

    To know the input of the future thermo-mechanical code, we have to get a better understanding of the thermo-physical evolution of the UF 6 which pressurizes the container. This evolution is function of: a) the heat transfer rate from the fire to the container b) the UF 6 behaviour in the container. These tests are essentially analytical at simulated fire temperatures of between 800 and 1000degC. They use a representative mass of UF 6 (around 4 tons). The tests will not seek to rupture the test container which has a diameter equal to the 48Y container, but shorter length. These tests carried out in realistic conditions (typical thermal gradient at the wall, characteristic period for UF 6 internal mass transfer) should make possible to improve knowledge of two fundamental phenomena: 1) vaporization of UF 6 on contact with the heated wall (around 400degC), a phenomenon which controls the container internal pressurization kinetic, 2) the equivalent conductivity of solid UF 6 , a phenomenon which is linked to the heat transfer by UF 6 vaporization-condensation through the solid's porosities and which depends on the diameter of the container. In addition, they will allow the influence of other parameters to be studied, such as UF 6 container filling mode or the mechanical characteristics of the container material. A UF 6 container fitted with instruments (wall temperature, UF 6 temperature, pressure) is heated by a rapid heat transient in a radiating furnace where the temperature and thermal power supplied can be measured. The test continues until pre-established thresholds have been reached: 1) strain threshold measured on the container surface (strain gauges positioned on the outside), 2) maximum temperature threshold of UF 6 , 3) container internal pressure threshold. (J.P.N.)

  3. Studies on (2UF4 + H2 = 2UF3 + 2HF) and vapour pressure of UF3

    International Nuclear Information System (INIS)

    Roy, K.N.; Prasad, R.; Venugopal, V.; Singh, Z.; Sood, D.D.

    1982-01-01

    Equilibrium constants for 2UF 4 (s) + H 2 (g) = 2UF 3 (s) + 2HF(g) have been measured in the temperature range 967 to 1120 K. An expression is given for the results. The results have been treated by second- and third-law methods to obtain ΔH 0 (298.15 K) and the values are given. The value of ΔS 0 (298.15 K) has been calculated by the second-law method. An expression is given for the vapour pressure of UF 3 (s), measured by the transpiration technique in the range 1229 to 1367 K. The standard enthalpy of vaporization ΔH 0 sub(v) (298.15 K) and the standard entropy of vaporization ΔS 0 sub(v) (298.15 K) have been calculated. The vaporization results have also been used for the calculation of ΔH 0 sub(f)(UF 3 , g, 298.15 K) and ΔS 0 sub(f)(UF 3 ,g, 298.15 K). (author)

  4. High temperature experiments on a 4 tons UF6 container TENERIFE program

    Energy Technology Data Exchange (ETDEWEB)

    Casselman, C.; Duret, B.; Seiler, J.M.; Ringot, C.; Warniez, P.

    1991-12-31

    The paper presents an experimental program (called TENERIFE) whose aim is to investigate the behaviour of a cylinder containing UF{sub 6} when exposed to a high temperature fire for model validation. Taking into account the experiments performed in the past, the modelization needs further information in order to be able to predict the behaviour of a real size cylinder when engulfed in a 800{degrees}C fire, as specified in the regulation. The main unknowns are related to (1) the UF{sub 6} behaviour beyond the critical point, (2) the relationship between temperature field and internal pressure and (3) the equivalent conductivity of the solid UF{sub 6}. In order to investigate these phenomena in a representative way it is foreseen to perform experiments with a cylinder of real diameter, but reduced length, containing 4 tons of UF{sub 6}. This cylinder will be placed in an electrically heated furnace. A confinement vessel prevents any dispersion of UF{sub 6}. The heat flux delivered by the furnace will be calibrated by specific tests. The cylinder will be changed for each test.

  5. Ultrahigh temperature vapor core reactor-MHD system for space nuclear electric power

    Science.gov (United States)

    Maya, Isaac; Anghaie, Samim; Diaz, Nils J.; Dugan, Edward T.

    1991-01-01

    The conceptual design of a nuclear space power system based on the ultrahigh temperature vapor core reactor with MHD energy conversion is presented. This UF4 fueled gas core cavity reactor operates at 4000 K maximum core temperature and 40 atm. Materials experiments, conducted with UF4 up to 2200 K, demonstrate acceptable compatibility with tungsten-molybdenum-, and carbon-based materials. The supporting nuclear, heat transfer, fluid flow and MHD analysis, and fissioning plasma physics experiments are also discussed.

  6. Reactions UF4 - ClO2F and UF5 - ClO2F

    International Nuclear Information System (INIS)

    Benoit, Raymond; Besnard, Ginette; Hartmanshenn, Olivier; Luce, Michel; Mougin, Jacques; Pelissie, Jean

    1970-02-01

    The study of the reaction UF 4 - ClO 2 F between 0 deg. and 100 deg. C, by various techniques (micro-sublimation, isopiestic method, IR and UV spectrography, thermogravimetry and X-ray diffraction) shows that intermediate steps are possible before the production of UF 5 . The whole reaction may be schematised by two equations: (1) n UF 4 + ClO 2 F → n UF x + ClO 2 (4 4 + ClO 2 F → UF x + 1/2 Cl 2 + O 2 . The more the temperature rises, the more the second equation becomes experimentally verified. The reaction at 0 deg. C between UF 5 and ClO 2 F may be represented by: UF 5 + ClO 2 F → UF 6 ClO 2 . The reactions: UF 5 + ClO 2 F → UF 6 + ClO 2 , UF 5 + ClO 2 F → UF 6 + 1/2 Cl 2 + O 2 are verified, the first and the second at 25 deg. C., the second from 50 deg. to 150 deg. C. From the results of AGRON it is possible to predict the residual solids before complete volatilization as UF 6 . The IR spectra of ClO 2 F adsorbed on UF 4 and UF x at 60 deg. C have been compared with those of gaseous ClO 2 F and UF 6 adsorbed on UF 4 . (authors) [fr

  7. Reactions UF{sub 4} - ClF, UF{sub 4} - ClF{sub 3}, UF{sub 5} - ClF, UF{sub 5} - ClF{sub 3}; Reactions UF{sub 4} - ClF, UF{sub 4} - ClF{sub 3}, UF{sub 5} - ClF, UF{sub 5} - ClF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Luce, M; Benoit, R; Hartmanshenn, O [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    The reaction between ClF{sub 3} and UF{sub 4} is partially explained by the study of the reactions of the three systems: UF{sub 4}-ClF, UF{sub 5}-ClF and UF{sub 5}-ClF{sub 3}. The analytical techniques used are: the micro-sublimation, the infra-red spectroscopy and the thermogravimetry. The origin of the by-products is indicated. (authors) [French] La reaction entre ClF{sub 3} et UF{sub 4} est partiellement expliquee grace a l'etude des reactions des trois systemes UF{sub 4}-ClF, UF{sub 5}-ClF et UF{sub 5}-ClF{sub 3}. Les techniques analytiques utilisees sont: la micro-sublimation, la spectroscopie infrarouge et la thermogravimetrie. L'origine des sous-produits est indiquee. (auteurs)

  8. The process research of drying UF4 by microwave

    International Nuclear Information System (INIS)

    Wen Guo; Wang Yunbo; Liu Long

    2010-01-01

    This paper make use of microwave to dry UF 4 filter cake, the aim is desorbed adsorption water. The research focus on such process conditions, boat material, thickness of filter cake, drying time, setting temperature, heating power and so on. the research of desorption crystal water of UF 4 that dried by microwave in fixed bed .When UF 4 drying by microwave and claiming by fixed bed, the qualified UF 4 powder is prepared. The research is shown that microwave can desorbs adsorption water which contain in UF 4 filter cake. There is a stable water contents in UF 4 after drying, and the sum of two members is less. After drying by microwave and claiming by fixed bed, the contents of water, UO 2 and UO 2 F 2 are all according to the quality standard. (authors)

  9. Kinetics of magnesiothermic reduction of UF4 by DTA

    International Nuclear Information System (INIS)

    Raina, Amulya; Agarwal, Renu

    2016-01-01

    Uranium metal production for nuclear fuel is usually carried out by magnesio-thermic reduction of UF 4 (s). This is a highly exothermic reaction: UF 4 +2Mg → 2MgF 2 + U, ΔH r 298.15 K = -349 kJ/mol. The process is carried out by loading 1:2 molar ratio of UF 4 and Mg mixture in a large stainless steel vessel lined with insulating MgF 2 . This bomb reactor is heated to ~1023 K, but the reaction is known to start at lower temperature. The furnace heat and reaction heat results in shooting mixture temperature to >1800 K. Attaining such high temperatures is desired for complete segregation of fluoride slag (T m MgF 2 =1538 K) and uranium melt (T m =1406 K) due to large difference in their densities, 3.4 gm/cc and 17.9 gm/cc, respectively. For efficient and economic magnesio-thermic reduction of UF 4 , it is desired to understand heat distribution in the reactor vessel, which requires kinetic parameters of this reaction: activation energy (E α ) and A. As this is a solid-solid reaction, studying this reaction kinetics can be approximated by nonisothermal DTA analysis using different heating rates. For non-isothermal conditions, the heating rate (ϕ) = dT/dt is related to rate of propagation of reaction

  10. Pilot plant UF6 to UF4 test operations report

    International Nuclear Information System (INIS)

    Bicha, W.J.; Fallings, M.; Gilbert, D.D.; Koch, G.E.; Levine, P.J.; McLaughlin, D.F.; Nuhfer, K.R.; Reese, J.C.

    1987-02-01

    The FMPC site includes a plant designed for the reduction of uranium hexafluoride (UF 6 ) to uranium tetrafluoride (UF 4 ). Limited operation of the upgraded reduction facility began in August 1984 and continued through January 19, 1986. A reaction vessel ruptured on that date causing the plant operation to be shut down. The DOE conducted a Class B investigation with the findings of the investigation board issued in preliminary form in May 1986 and as a final recommendation in July 1986. A two-phase restart of the plant was planned and implemented. Phase I included implementing safety system modifications, changing reaction vessel temperature control strategy, and operating the reduction plant under an 8-week controlled test. The results of the test period are the subject of this report. 41 figs., 11 tabs

  11. A study of UF4 preparations

    International Nuclear Information System (INIS)

    Chang, I.S.; Doh, J.B.; Choi, Y.D.

    1985-05-01

    Uranium tetrafluoride (UF 4 ), green salt, is very important intermediate in the production of metallic uranium and uranium hexafluoride (UF 6 ) for enrichment. The hydrofluorination of uranium dioxide (UO 2 ) with anhydrous hydrogen fluoride (HF), produced from ADU (ammonium diuranate) process or AUC (ammonium uranyl carbonate) process, are commercially used for the production of uranium tetrafluoride. At present, a new approach such as direct UF 4 preparation at the mine-site without further precipitation, filteration and drying of yellow cake from leaching solution has been studied. The single step continous reduction of uranium hexafluoride to uranium tetrafluoride is one of the most interesting process being applied for the commercial use of a large amount of depleted UF 6 which is produced in tail after enrichment. The direct conversion of UF 6 and UF 4 with hydrogen and fluorine gases using cold wall reactor has a certain advantage over various wet process such as AUD and AUC processes in which hydrolysis of UF 6 and various kind of chemicals are required, including liquid waste treatment. This report reviews and analyzes the theory and processes being used commercially or under study. (Author)

  12. P-T-x phase diagrams of MeF-UF4(Me=Li-Cs) systems

    International Nuclear Information System (INIS)

    Korenev, Yu.M.; Rykov, A.N.; Varkov, M.V.; Novoselova, A.V.

    1988-01-01

    Vapor composition and general pressure at three-phase equilibria in the MeF-UF 4 (Me=Li-Cs) systems are calculated using the values of independent component activities obtained earlier together with the data on fusibility diagrams. P-T and T-x projections of phase diagrams of these systems are constructed

  13. Thermodynamic assessment of the LiF–ThF{sub 4}–PuF{sub 3}–UF{sub 4} system

    Energy Technology Data Exchange (ETDEWEB)

    Capelli, E. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Department of Radiation Science and Technology, Faculty of Applied Physics, Delft University of Technology, Delft 2629JB (Netherlands); Beneš, O., E-mail: ondrej.benes@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Konings, R.J.M. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Department of Radiation Science and Technology, Faculty of Applied Physics, Delft University of Technology, Delft 2629JB (Netherlands)

    2015-07-15

    The LiF–ThF{sub 4}–PuF{sub 3}–UF{sub 4} system is the reference salt mixture considered for the Molten Salt Fast Reactor (MSFR) concept started with PuF{sub 3}. In order to obtain the complete thermodynamic description of this quaternary system, two binary systems (ThF{sub 4}–PuF{sub 3} and UF{sub 4}–PuF{sub 3}) and two ternary systems (LiF–ThF{sub 4}–PuF{sub 3} and LiF–UF{sub 4}–PuF{sub 3}) have been assessed for the first time. The similarities between CeF{sub 3}/PuF{sub 3} and ThF{sub 4}/UF{sub 4} compounds have been taken into account for the presented optimization as well as in the experimental measurements performed, which have confirmed the temperatures predicted by the model. Moreover, the experimental results and the thermodynamic database developed have been used to identify potential compositions for the MSFR fuel and to evaluate the influence of partial substitution of ThF{sub 4} by UF{sub 4} in the salt.

  14. Sensitivity of UF-R, UF-VCh, UF-VR films used for soft x-ray (lambda=2+10A) detection

    International Nuclear Information System (INIS)

    Aglitskij, E.V.; Bojko, V.A.; Kalinkina, T.A.

    1975-01-01

    The sensitometric characteristics of the following types of photographic film were measured in the range of wavelengths 2-10A: UF-R, UF-VCh, and UF-VR. It was demonstrated that UF-VR photographic film is four times as sensitive as UF-R film and 1.6 times as sensitive as UF-VCh film; it is also most suitable film for x-ray spectroscopy of multiply charged ions and for diagnosing high-temperature laser plasma

  15. Sensitometric characteristics of UF-4, UF-5, and UFSh-O films in the quantum-energy range of 5-30 keV

    International Nuclear Information System (INIS)

    Datsko, I.M.; Slabkovskaya, M.A.; Sokolov, A.S.; Uvarova, N.V.; Sheromov, M.A.

    1987-01-01

    The sensitivity, gamma, and transmission of UF-4, UF-5, and UFSh-O for quanta with energies of 5-30 keV extracted from a beam of synchrotron radiation are measured. UFSh-O photographic film is more sensitive by a factor of 1.5-2 than are the UF-4 and UF-5 films. The gamma of all the films is greatly dependent on the quantum energy

  16. Aspects of uranium chemistry pertaining to UF{sub 6} cylinder handling

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, R.L.; Barber, E.J. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)

    1991-12-31

    Under normal conditions, the bulk of UF{sub 6} in storage cylinders will be in the solid state with an overpressure of gaseous UF{sub 6} well below one atmosphere. Corrosion of the interior of the cylinder will be very slow, with formation of a small amount of reduced fluoride, probably U{sub 2}F{sub 9}. The UO{sub 3}-HF-H{sub 2}O phase diagram indicates that reaction of any inleaking water vapor with the solid UF{sub 6} will generate the solid material [H{sub 3}O]{sub 2}(U(OH){sub 4}F{sub 4}) in equilibrium with an aqueous HF solution containing only small amounts of uranium. The corrosion of the steel cylinder by these materials may be enhanced over that observed with gaseous anhydrous UF{sub 6}.

  17. Obtaining of uranium tetrafluoride UF4 by electrodialysis reactive from uranium concentrates

    International Nuclear Information System (INIS)

    Munoz Lay, Danny Mauricio

    2014-01-01

    The generation of uranium fuels has always been a topic worldwide. The uranium fuel manufacturing base is made under very strict parameters of radiological and industrial safety, being a stage called 'nuclear fuel cycle'. In Chile, it is done constant research for fuels. This report focuses primarily on participating in such research; mainly in the production of uranium tetrafluoride (UF 4 ) .The tetrafluoride production is very crucial for the nuclear fuel industry. Its production varies from precipitation in stirred conditions to electrolysis in mercury. However, both processes has shortcomings either in performance and environmental pollution, which is why it is proposed a new method of production based on a friendly process to the environment and easier to operate, the reactive electrodialysis (RED). Electrodialysis is a hybrid reactive process of separation by membranes, cationic and / or anionic, namely, ionic species. In the process, ions are induced to move by an electric potential applied and separated by these membranes, a highly selective physical barrier which allows passage of ions with certain charge, and prevents the passage of oppositely charged ions. And in turn, it is reactive because it forces a chemical reaction, redox, to obtain uranium tetrafluoride (UF 4 ). The results of these experiments show that by reactive electrodialysis, NH 4 UF 5 deposits were obtained. However, calcinating the NH 4 UF 5 to 450 o C, it decomposes to obtain uranium tetrafluoride, UF 4 . The best working conditions were obtained with an electric current of 0.5 (A), 41 o C and a flow of 16 (ml / s) of the electrolyte. It was possible to obtain 5,995 (g) to 3 (h), giving a current efficiency of 71.42%. In turn, working at high temperatures and flow recirculation is possible to operate with a potential difference of 1.7 (V)

  18. Thermal reactions of uranium metal, UO 2, U 3O 8, UF 4, and UO 2F 2 with NF 3 to produce UF 6

    Science.gov (United States)

    McNamara, Bruce; Scheele, Randall; Kozelisky, Anne; Edwards, Matthew

    2009-11-01

    This paper demonstrates that NF 3 fluorinates uranium metal, UO 2, UF 4, UO 3, U 3O 8, and UO 2F 2·2H 2O to produce the volatile UF 6 at temperatures between 100 and 550 °C. Thermogravimetric and differential thermal analysis reaction profiles are described that reflect changes in the uranium fluorination/oxidation state, physiochemical effects, and instances of discrete chemical speciation. Large differences in the onset temperatures for each system investigated implicate changes in mode of the NF 3 gas-solid surface interaction. These studies also demonstrate that NF 3 is a potential replacement fluorinating agent in the existing nuclear fuel cycle and in actinide volatility reprocessing.

  19. Computational simulation studies of the reduction process of UF4 to metallic uranium

    International Nuclear Information System (INIS)

    Borges, Wesden de Almeida

    2011-01-01

    The production of metallic uranium is essential for production of fuel elements for using in nuclear reactors manufacturing of radioisotopes and radiopharmaceuticals. In IPEN, metallic uranium is produced by magnesiothermical reduction of UF 4 . This reaction is performed in a closed graphite crucible inserted in a sealed metal reactor and no contact with the outside environment. The set is gradually heated in an oven pit, until it reaches the ignition temperature of the reaction (between 600-650 degree C). The modeling of the heating profile of the system can be made using simulation programs by finite element method. Through the thermal profiles in the load, we can have a notion of heating period required for the reaction to occur, allowing the identification of the same group in a greater or smaller yield in metallic uranium production. Thermal properties of UF 4 are estimated, obtaining thermal conductivity and heat capacity using the Flash Laser Method, and for the load UF 4 + Mg, either. The results are compared to laboratory tests to simulate the primary production process. (author)

  20. Technical documentation of HGSYSTEM/UF6 model

    International Nuclear Information System (INIS)

    Hanna, S.R.; Chang, J.C.; Zhang, J.X.

    1996-01-01

    MMES has been directed to upgrade the safety analyses for the gaseous diffusion plants at Paducah KY and Piketon OH. These will require assessment of consequences of accidental releases of UF 6 to the atmosphere at these plants. The HGSYSTEM model has been chosen as the basis for evaluating UF 6 releases; it includes dispersion algorithms for dense gases and treats the chemistry and thermodynamics of HF, a major product of the reaction of UF 6 with water vapor in air. Objective of this project was to incorporate additional capability into HGSYSTEM: UF 6 chemistry and thermodynamics, plume lift-off algorithms, and wet and dry deposition. The HGSYSTEM modules are discussed. The hybrid HGSYSTEM/UF 6 model has been evaluated in three ways

  1. Conversion of non-nuclear grade feedstock to UF4

    International Nuclear Information System (INIS)

    Ponelis, A.A.; Slabber, M.N.; Zimmer, C.H.E.

    1987-01-01

    The South African Conversion route is based on the direct feed of ammonium di-uranate produced by any one of a number of different mines. The physical and chemical characteristics of the feedstock can thus vary considerably and influence the conversion rate as well as the final UF 6 product purity. The UF 4 conversion reactor is a Moving Bed Reactor (MBR) with countercurrent flow of the reacting gas phases. Initial problems to continuously operate the MBR were mostly concerned with the physical nature of the UO 3 feed particles. Different approaches to eventually obtain a successful MBR are discussed. Besides obtaining UO 3 feed particles with certain physical attributes, the chemical impurities also have an effect on the operability of the MBR. The influence of the feedstock variables on the reduction and hydrofluorination rates after calcining has largely been determined from laboratory and pilot studies. The effect of chemical impurities such as sodium and potassium on the sinterability of the reacting particles and therefore the optimum temperature range in the MBR is also discussed. Confirmation of the effect of sodium and potassium impurities on the conversion rate has been obtained from large scale reactor operation. (author)

  2. Photoionization mass spectrometry of UF6

    International Nuclear Information System (INIS)

    Berkowitz, J.

    1979-01-01

    The photoionization mass spectrum of 238 UF 6 was obtained. At 600 A = 20.66 eV, the relative ionic abundances were as follows: UF 6 + , 1.4; UF 5 + , 100; UF + , 17; UF 3 + , approx. 0.7; UF 2 + , very weak; UF + , very weak; U + , essentially zero. The adiabatic ionization potential for UF 6 was 13.897 +- 0.005 eV. The production of UF 5 + begins at approx. 887 A = 13.98 eV, at which energy the UF 6 + partial cross section abruptly declines and then levels off. This behavior suggests the vague possibility of an isotope effect. The UF 4 + signal begins at approx. 725 A = 17.10 eV, at which energy the UF 5 + signal reaches a plateau value. The UF 5 + photoionization yield curve displays some autoionization structure from its threshold to approx. 750 A

  3. Determination of UO2 little quantity in UF4 by X-rays diffraction

    International Nuclear Information System (INIS)

    Costa, M.I.; Sato, I.M.; Imakuma, K.

    1977-01-01

    In the fluorination process, the final product UF 4 contain different levels of UO 2 as a contaminant. A routine method for quantitative analysis by x-ray diffraction has been developed. Standard curves have been plotted using mixtures of UO 2 /UF 4 with measures of intensity of (III) peak of UO 2 by the step scanning process. The integrated intensity versus UO 2 concentration curves present a linear behavior in the range from 0 to 4%. A good reprodutibility of measuring process has been observed through statistical analysis which permits to determine low fractions of UO 2 in UF 4 with +- 0,08% of accuracy [pt

  4. Modeling and analyses of postulated UF6 release accidents in gaseous diffusion plant

    International Nuclear Information System (INIS)

    Kim, S.H.; Taleyarkhan, R.P.; Keith, K.D.; Schmidt, R.W.; Carter, J.C.; Dyer, R.H.

    1995-10-01

    Computer models have been developed to simulate the transient behavior of aerosols and vapors as a result of a postulated accident involving the release of uranium hexafluoride (UF 6 ) into the process building of a gaseous diffusion plant. UF 6 undergoes an exothermic chemical reaction with moisture (H 2 O) in the air to form hydrogen fluoride (HF) and radioactive uranyl fluoride (UO 2 F 2 ). As part of a facility-wide safety evaluation, this study evaluated source terms consisting of UO 2 F 2 as well as HF during a postulated UF 6 release accident in a process building. In the postulated accident scenario, ∼7900 kg (17,500 lb) of hot UF 6 vapor is released over a 5 min period from the process piping into the atmosphere of a large process building. UO 2 F 2 mainly remains as airborne-solid particles (aerosols), and HF is in a vapor form. Some UO 2 F 2 aerosols are removed from the air flow due to gravitational settling. The HF and the remaining UO 2 F 2 are mixed with air and exhausted through the building ventilation system. The MELCOR computer code was selected for simulating aerosols and vapor transport in the process building. MELCOR model was first used to develop a single volume representation of a process building and its results were compared with those from past lumped parameter models specifically developed for studying UF 6 release accidents. Preliminary results indicate that MELCOR predicted results (using a lumped formulation) are comparable with those from previously developed models

  5. Thermodynamic assessment of the LiF–ThF4–PuF3–UF4 system

    NARCIS (Netherlands)

    Capelli, E.; Benes, O.; Konings, R.J.M.

    2015-01-01

    The LiF–ThF4–PuF3–UF4 system is the reference salt mixture considered for the Molten Salt Fast Reactor (MSFR) concept started with PuF3. In order to obtain the complete thermodynamic description of this quaternary system, two binary systems (ThF4–PuF3 and UF4–PuF3) and two ternary systems

  6. The determination of UO2 and UF4 in fused fluoride salts

    International Nuclear Information System (INIS)

    Batiste, D.J.; Lee, D.A.

    1989-01-01

    The determination of uranium oxide solubilities in fused fluoride salts is important in the electrolytic preparation of uranium metal. This project was initiated to develop a method for the determination of UO 2 separately from UF 4 in UF 4 -CaF 2 -LiF fused salts. Previous methods used for the determination of UO 2 in fused fluoride salts involved inert gas fusions where oxygen was liberated as CO 2 , and hydrofluorination where oxygen was released as H 2 O; but the special equipment used for these procedures was no longer available. These methods assumed that all of the oxygen liberated was due to UO 2 and does not consider impurities from reagents and other oxygen sources that amount to a bias of approximately 0.3 wt %. This titrimetric method eliminates the bias by selectively extracting the UF 4 with a Na 2 EDTA-H 3 BO 3 solution. The remaining uranium oxide residue is treated and titrated gravimetrically to a potentiometric endpoint with NBS standard K 2 Cr 2 O 7 . An aliquot of the Na 2 EDTA-H 3 BO 3 extract is also titrated gravimetrically to a potentiometric endpoint, this uranium component is determined and calculated as UF 4 . 4 refs., 2 figs., 2 tabs

  7. Thermodynamic assessment of the LiF-NaF-ThF4-UF4 system

    International Nuclear Information System (INIS)

    Benes, O.; Beilmann, M.; Konings, R.J.M.

    2010-01-01

    A thermodynamic assessment of the LiF-NaF-ThF 4 -UF 4 system is presented in this study. The binary phase diagrams are optimized based on the known experimental data and the excess Gibbs energies of liquid and solid solutions are described using a modified quasi chemical model and polynomial formalism respectively. The higher order systems are extrapolated according to asymmetric Toop mathematical formalism. Based on the developed thermodynamic database the fuel composition of the molten salt fast reactor is optimized. In total three different fuel compositions are identified. Properties of these fuel compositions such as melting point, vapour pressure and the boiling temperature are derived from the obtained thermodynamic assessment and are presented in this study.

  8. UF{sub 6} pressure excursions during cylinder heating

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.G. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    As liquid UF{sub 6} inside a cylinder changes from a liquid to a solid, it forms a porous solid which occupies approximately the same volume as that of the liquid before cooling. Simultaneously as the liquid cools, UF{sub 6} vapor in the cylinder ullage above the liquid desublimes on the upper region of the inner cylinder wall. This solid is a dense, glass-like material which can accumulate to a significant thickness. The thickness of the solid coating on the upper cylinder wall and directly behind the cylinder valve area will vary depending on the conditions during the cooling stage. The amount of time lapsed between UF{sub 6} solidification and UF{sub 6} liquefaction can also affect the UF{sub 6} coating. This is due to the daily ambient heat cycle causing the coating to sublime from the cylinder wall to cooler areas, thus decreasing the thickness. Structural weakening of the dense UF{sub 6} layer also occurs due to cylinder transport vibration and thermal expansion. During cylinder heating, the UF{sub 6} nearest the cylinder wall will liquefy first. As the solid coating behind the cylinder valve begins to liquefy, it results in increased pressure depending upon the available volume for expansion. At the Paducah Gaseous Diffusion Plant (PGDP) during the liquefaction of the UF{sub 6} in cylinders in the UF{sub 6} feed and sampling autoclaves, this pressure increase has resulted in the activation of the systems rupture discs which are rated at 100 pounds per square inch differential.

  9. Metamorphosis: Phases of UF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, R.H. [Department of Energy, Oak Ridge, TN (United States)

    1991-12-31

    A 15-minute videotape is presented. The subject matter is 150 grams of UF{sub 6} sealed in a glass tube. Close-up views show the UF{sub 6} as phase changes are effected by the addition or removal of heat from the closed system. The solid-to-liquid transition is shown as heat is added, both slowly and rapidly. The solid phases which result from freezing and from desublimation are contrasted. In the solid state, uranium hexafluoride is a nearly-white, dense crystalline solid. The appearance of this solid depends on whether it is formed by freezing from the liquid or by desublimation from the vapor phase. If frozen from the liquid, the solid particles take the form of irregularly shaped coarse grains, while the solid product of desublimation tends to be a rather formless mass without individually distinguishable particles. The changes in state are presented in terms of the UF{sub 6} phase diagram.

  10. Computer programs for developing source terms for a UF{sub 6} dispersion model to simulate postulated UF{sub 6} releases from buildings

    Energy Technology Data Exchange (ETDEWEB)

    Williams, W.R.

    1985-03-01

    Calculational methods and computer programs for the analysis of source terms for postulated releases of UF{sub 6} are presented. Required thermophysical properties of UF{sub 6}, HF, and H{sub 2}O are described in detail. UF{sub 6} reacts with moisture in the ambient environment to form HF and H{sub 2}O. The coexistence of HF and H{sub 2}O significantly alters their pure component properties, and HF vapor polymerizes. Transient compartment models for simulating UF{sub 6} releases inside gaseous diffusion plant feed and withdrawl buildings and cascade buildings are also described. The basic compartment model mass and energy balances are supported by simple heat transfer, ventilation system, and deposition models. A model that can simulate either a closed compartment or a steady-state ventilation system is also discussed. The transient compartment models provide input to an atmospheric dispersion model as output.

  11. Automation of the Process to Obtain U F{sub 4} Powders; Ingenieria Basica para la Automatizacion del Proceso de Obtencion de Polvos de UF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Fenocchio, A D [Instituto Balseiro, Universidad Nacional de Cuyo, Centro Atomico Bariloche, Universidad de Buenos Aires (Argentina)

    2001-07-01

    Here is exposed the preliminary analysis of the control system to be implemented in the Production Plant of UF{sub 4} Powders.The work has been done in the electronic laboratory.This implies, the setting of devices (PLC, Temperature Controllers, etc.) and the setting of the communications using the proper protocol.Also is shown a study about the logic for the first part of the conversion process of UF{sub 6}: the evaporation.This study is used to define the methodology to follow in a future PLC program.

  12. High temperature vapors science and technology

    CERN Document Server

    Hastie, John

    2012-01-01

    High Temperature Vapors: Science and Technology focuses on the relationship of the basic science of high-temperature vapors to some areas of discernible practical importance in modern science and technology. The major high-temperature problem areas selected for discussion include chemical vapor transport and deposition; the vapor phase aspects of corrosion, combustion, and energy systems; and extraterrestrial high-temperature species. This book is comprised of seven chapters and begins with an introduction to the nature of the high-temperature vapor state, the scope and literature of high-temp

  13. Adducts of UF5 with SbF5 and structure of UF5 . 2SbF5

    International Nuclear Information System (INIS)

    Sawodny, W.; Rediess, K.

    1980-01-01

    Both α-UF 5 and β-UF 5 form only a 1:2 compound UF 5 . 2SbF 5 reacting directly with SbF 5 , from which UF 5 . SbF 5 can be obtained by thermal decomposition. UF 5 . 2SbF 5 crystallizes in the monoclinic space group P2 1 /c with the following lattice constants a = 8.110(4), b = 14.129(6), c = 10.032(6) A and β = 96.97(5) 0 ; Z = 4. An X-ray study shows centrosymmetric four-membered rings of alternating UF 8 and SbF 6 polyhedra connected by other SbF 6 entities. This structure is similar to that of UOF 5 . 2SbF 5 , but the distorted pentagonal-bipyramidal coordination of the U atom found there is increased to a dodecahedral coordination by an additional U-F-Sb bridge, though with a somewaht larger UF distance. (author)

  14. PERFORMA NEUTRONIK BAHAN BAKAR LiF-BeF2-ThF4-UF4 PADA SMALL MOBILE-MOLTEN SALT REACTOR

    Directory of Open Access Journals (Sweden)

    S. N. Rokhman

    2015-04-01

    Full Text Available Telah dilakukan analisis terhadap performa neutronik bahan bakar garam lebur LiF-BeF2-ThF4-UF4 pada Small Mobile-Molten Salt Reactor (SM-MSR. Penyesuaian konfigurasi teras dan temperatur operasi harus dilakukan untuk penggunaan bahan bakar baru tersebut agar mencapai keff > 1 dan CR (conversion ratio > 1 pada fraksi 0,5% 233U, 20% 232Th, 28% Li, 51,5% Be. Setelah didapat nilai keff ≈ 1 dan CR ≈ 1, dilakukan analisis pengaruh perubahan Th terhadap Be dan Be terhadap Li yang terlihat dalam perubahan parameter keff dan CR. Setelah itu fraksi 233U divariasi antara 0,5–0,46% untuk memperoleh keff > 1 dan CR > 1. Dalam perhitungan koefisien reaktifitas temperatur (αT, temperatur teras dinaikkan sebesar +25K dan +50K., dan untuk koefisien reaktifitas void (αV, densitas bahan bakar dikurangi hingga 90%. Hasil perhitungan menunjukkan bahwa pengurangan Th terhadap Be menyebabkan penurunan nilai CR dan naiknya keff akibat berkurangnya material fertil. Sebaliknya penambahan Be terhadap Li mengakibatkan terjadi kenaikan nilai keff dan menurunkan CR, akibat laju serapan Li lebih besar dari Be. Pada 5 (lima fraksi 233U dalam rentang 0,5–0,49%, hasil perhitungan keff dan CR masing-masing bervariasi dalam rentang 1,00001 - 1,00327 dan 1,00016 - 1,00731. Untuk faktor puncak daya (PPF, hasil perhitungan memberikan nilai dalam rentang 2,4311 -2,4714. Sedangkan untuk parameter keselamatan, koefisien reaktivitas temperatur (αT dan reaktivitas void (αV masingmasing bernilai negatif dalam rentang 4,972×10-5 - 5,909×10-5 dan 2,596×10-2- 2,8287×10-2 ∆k/k/K. Dapat disimpulkan bahwa teras SM-MSR memberikan nilai negatif di kedua koefisien reaktivitas tersebut untuk setiap fraksi,, sehingga memenuhi kriteria keselamatan dan keselamatan melekat. Kata kunci: SM-MSR (small mobile-molten salt reactor, bahan bakar LiF-BeF2-ThF4-UF4, keselamatan melekat, koefisien reaktivitas temperatur, koefisien reaktivitas void   The analysis of neutronic performance has

  15. Experimental Determination of the Solubility of Industrial UF4 Particles

    International Nuclear Information System (INIS)

    Chazel, V.; Houpert, P.; Paquet, F.; Ansoborlo, E.; Henge-Napoli, M.H.

    2000-01-01

    The chemical solubility in cell culture medium and in Gamble's solution and the biokinetic behaviour on rats of an industrial UF 4 compound have been studied in order to predict experimentally absorption parameters (f r , s r , s s ) after inhalation and to provide data for interpreting bioassay data. According to these results, this compound has been found to have an intermediate type of absorption between Types F and M as designated by ICRP for the human respiratory tract. A dose coefficient of 1.4 μSv.Bq -1 has been calculated for an inhaled aerosol with an AMAD of 5.1 μm (σg 2.5), which corresponded to the mean value encountered at the fluorination workplace. Predictive urinary and faecal excretion and lung retention curves have also been deduced to calculate the incorporated activity and the received dose in case of an inhalation of UF 4 by workers. (author)

  16. Nuclear vapor thermal reactor propulsion technology

    International Nuclear Information System (INIS)

    Maya, I.; Diaz, N.J.; Dugan, E.T.; Watanabe, Y.; McClanahan, J.A.; Wen-Hsiung Tu; Carman, R.L.

    1993-01-01

    The conceptual design of a nuclear rocket based on the vapor core reactor is presented. The Nuclear Vapor Thermal Rocket (NVTR) offers the potential for a specific impulse of 1000 to 1200 s at thrust-to-weight ratios of 1 to 2. The design is based on NERVA geometry and systems with the solid fuel replaced by uranium tetrafluoride (UF 4 ) vapor. The closed-loop core does not rely on hydrodynamic confinement of the fuel. The hydrogen propellant is separated from the UF 4 fuel gas by graphite structure. The hydrogen is maintained at high pressure (∼100 atm), and exits the core at 3,100 K to 3,500 K. Zirconium carbide and hafnium carbide coatings are used to protect the hot graphite from the hydrogen. The core is surrounded by beryllium oxide reflector. The nuclear reactor core has been integrated into a 75 klb engine design using an expander cycle and dual turbopumps. The NVTR offers the potential for an incremental technology development pathway to high performance gas core reactors. Since the fuel is readily available, it also offers advantages in the initial cost of development, as it will not require major expenditures for fuel development

  17. Actual and Idealized Crystal Field Parameterizations for the Uranium Ions in UF 4

    Science.gov (United States)

    Gajek, Z.; Mulak, J.; Krupa, J. C.

    1993-12-01

    The crystal field parameters for the actual coordination symmetries of the uranium ions in UF 4, C2 and C1, and for their idealizations to D2, C2 v , D4, D4 d , and the Archimedean antiprism point symmetries are given. They have been calculated by means of both the perturbative ab initio model and the angular overlap model and are referenced to the recent results fitted by Carnall's group. The equivalency of some different sets of parameters has been verified with the standardization procedure. The adequacy of several idealized approaches has been tested by comparison of the corresponding splitting patterns of the 3H 4 ground state. Our results support the parameterization given by Carnall. Furthermore, the parameterization of the crystal field potential and the splitting diagram for the symmetryless uranium ion U( C1) are given. Having at our disposal the crystal field splittings for the two kinds of uranium ions in UF 4, U( C2) and U( C1), we calculate the model plots of the paramagnetic susceptibility χ( T) and the magnetic entropy associated with the Schottky anomaly Δ S( T) for UF 4.

  18. FTIR spectroscopy of UF6 clustering in a supersonic Laval nozzle

    International Nuclear Information System (INIS)

    Tanimura, Shinobu; Okada, Yoshiki; Takeuchi, Kazuo

    1996-01-01

    The clustering of UF 6 seeded in Ar was observed in a continuous supersonic Laval nozzle flow. The onset conditions for UF 6 clustering were investigated by measuring the FTIR spectra of UF 6 monomer and clusters in the nozzle. The onset conditions for the clustering, temperature, density of UF 6 (or partial pressure), and cooling rate, were determined. The onset temperature determined here was higher by 40-50 K than that determined by a light-scattering method. The frequency shift of the main peak of the UF 6 clusters from the monomer peak was about -17 cm -1 , which was smaller than the shift of the crystalline UF 6 by about 11 cm -1 . The increase in temperature caused by the heat of condensation and the change of the spectra of UF 6 clusters with the growth after the onset were also observed. It was shown that the clustering rate due to the collision between the monomer and cluster is much higher than that due to the collision between the monomers. 19 refs., 9 figs

  19. Economical and neutronic performance of HYLIFE-II with mixture of 90% flibe + 10% UF4 (or ThF4)

    International Nuclear Information System (INIS)

    Uenalan, Sebahattin

    2004-01-01

    This work investigated the neutronics behavior and the economics of the HYLIFE-II reactor with ThF 4 and UF 4 , which produces an electrical power of 1 GW from the fusion power of 2.857 GW during the operation period of 30 years. The use of ThF 4 and UF 4 is realized by a mixture zone consisted of 90% flibe (Li 2 BeF 4 ) and 10% fuel, instead of 100% flibe coolant. The mixture compositions are selected as 90% flibe + 10% UF 4 , 90% flibe + 10% ThF 4 and 90% flibe + 5% UF 4 + 5% ThF 4 . The capacity factor of the reactor is 0.75. The mixtures, with zone thickness of 65 cm were circulated with periods of 20.22, 19.89 and 20.11 s during the operation period of 30 years, respectively. In addition, for flibe + UF 4 , power stabilization by means of plutonium separation from the mixture was applied. The use of fuel materials in the HYLIFE-II reactor resulted in high energy production, sufficient tritium breeding, significant fissile fuel breeding and low radiation damage in the first wall. The average values of tritium breeding ratio over 30 years are between 1.08 and 1.12, higher than 1.0 indicating sufficient tritium breeding. Generally, the mixtures with ThF 4 show better performance than the mixture with UF 4 in terms of more energy production and significant fissile fuel breeding. The neutronic performance of the reactor increases with the operational period. However, the stabilization process performed after operation for 6 years causes all neutronic values to remain nearly constant during the followed operation time. At the 6th year of operation, the power production, which is ∼1540 MW(electric) at startup, reached the electrical power of 2 GW for flibe + UF 4 . The power production without the separation process reached ∼3500 MW(electric) for the mixtures with ThF 4 and ∼3000 MW(electric) for the mixture with UF 4 . At the end of the operation period, helium production values in the first wall, made of Hastelloy, are calculated as 590 ppm without the

  20. Investigation of the UF6 aerosol behavior in air, (4)

    International Nuclear Information System (INIS)

    Ishida, Junichiro; Sakamoto, Genji; Takeda, Seiichi; Kato, Jinzo

    1979-01-01

    When gaseous uranium hexafluoride (UF 6 ) is released into air, it hydrolizes with moisture in air to produce HF gas and particulate UO 2 F 2 which is visible. The lowest visible concentration in air is about 5 x 10 -8 μCi/cm 3 in case of releasing UF 6 and about 10 -9 μCi/cm 3 in case of released UF 6 cloud. By watching the occurrence of released UF 6 cloud, it is possible to take necessary action without delay. But in the case that there is no one to watch or that the concentration is not high enough to be visible, an alarm monitor system has to be relied on. Therefore the characteristics of the alarm monitors which can detect UF 6 promptly were examined. As UF 6 is hydrolized into gaseous HF and particulate UO 2 F 2 , three monitoring methods are considered; (1) to detect the alpha radiation of uranium, (2) to detect HF gas and (3) to detect airborne particles (aerosol). Performance tests were conducted on an alpha dust monitor, an electrochemical HF monitor, a thin film electrolyte HF monitor and an ionized smoke detector. The relationship between radioactivity concentration and HF concentration was investigated especially regarding with the conditions of released UF 6 amount and the distance from a release point to the observation point. The experimental facilities containing a large glove-box made of SUS and acrylic resin walls, a dust monitor, an HF monitor, a smoke detector and a filter, and the experimental procedure are explained. As the experimental results, the response characteristics of the dust monitor and HF monitor, the relationship of radioactivity concentration to HF concentration in air and the relation of the distance from the release point to the concentration of U and HF are presented. (Nakai, Y.)

  1. Role of contaminants in the fluorination of β-UO3 to UF4 by freon-12

    International Nuclear Information System (INIS)

    Girgis, B.S.; Rofail, N.H.

    1992-01-01

    Ammonium uranate was precipitated from uranyl nitrate or sulphate by NH 3 gas or urea, and decomposed to β-UO 3 by calcination at 623 or 773 K. Oxides contaminated by high contents of nitrates (non-washed uranate) displayed higher conversion to UF 4 in comparison to the respective pre-washed uranate. Products of thermal treatment at 623 K were also more reactive towards fluorination, which was ascribed to the highly-disordered, loosely bound, high surface area products. The presence of residual nitrate, and probably ammonium, ions help in the partial reduction to lower oxides and in preventing recrystallization of the reaction solids. Ammonium uranate precipitated from uranyl sulphate and decomposed at 623 K is more easily fluorinated than the product decomposed at 773 K; it is also better product for fluorination than the uranate precipitated from uranyl nitrate. The complete conversion to UF 4 i attained after 45 min with the uranate precipitated from uranyl sulphate and treated at 623 K, but it needs 120 min with the product formed from uranyl nitrate and decomposed at the same temperature. (orig.)

  2. Perekayasaan Heat Exchanger Sebagai Pemanas Umpan Uf 6 Dalam Pabrik Elemen Bakar Nuklir

    OpenAIRE

    Zacharias, Petrus; Pancoko, Marliyadi

    2011-01-01

    DESIGN OF HEAT EXCHANGER FOR HEATING UF6 FEED IN NUCLEAR FUEL ELEMENT PLANT. The process of conversion of UF6 to UO through Integrated Dry Route (IDR) i s done in a rotary kiln reactor. There are two stages of initi al treatment / conditioni ng before inserting the UF 6 in to the reactor : changing UF6 2 solid into the gas phase at a temperature of 60°C in an evaporator, and then, raising the temperature of UF C to 2900 C i n a Heat Exchanger (HE). Therefore it i s necessary to desi gn...

  3. Temperature evaluation of UF6 and cluster detection in nozzle expansion using low-resolution infrared absorption spectroscopy

    International Nuclear Information System (INIS)

    Sbampato, M.E.; Antunes, L.M.D.; Miranda, S.F.; Sena, S.C.; Santos, A.M.

    1998-01-01

    The continuous supersonic expansion of pure gaseous UF 6 and mixtures of UF 6 with argon and nitrogen through a bidimensional nozzle was studied using low-resolution infrared spectroscopy in the ν 3 absorption band region. The experiments were carried out in order to calculate the molecular temperature of the beam and also to verify cluster formation in the expansion. The molecular beam temperature evaluation was based on the measurements of the low-resolution bandwidth, which were compared to simulated spectra results. The temperatures were also evaluated using the measured pressure at the end of the nozzle by a Pitot tube. In the conditions where no cluster formation was observed the calculated theoretical temperatures using an equilibrium expansion model are in good agreement with the data obtained through the analysis of the experimental spectra and through the Pitot tube pressure measurement. Cluster formation was observed for temperatures below about 120 K. In these conditions the infrared spectra showed shoulders in the region above 630 cm -1 and a shoulder or band between 616 and 600 cm -1 . (orig.)

  4. Probing the electronic structures of low oxidation-state uranium fluoride molecules UF{sub x}{sup −} (x = 2−4)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Li; Jian, Tian; Lopez, Gary V.; Wang, Lai-Sheng, E-mail: lai-sheng-wang@brown.edu [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States); Hu, Han-Shi; Li, Jun, E-mail: junli@tsinghua.edu.cn [Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China); William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Su, Jing [Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2013-12-28

    We report the experimental observation of gaseous UF{sub x}{sup −} (x = 2−4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UF{sub x} (x = 2−4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f{sup 3}7s{sup 2})F{sub 2}{sup −}, as a result of strong electron correlation effects of the two 7s electrons. The U−F symmetric stretching vibrational modes are resolved for the ground states of all UF{sub x} (x = 2−4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UF{sub x}{sup −} and UF{sub x} (x = 1−6) series are considered theoretically to examine the trends of U−F bonding and the electron affinities as a function of fluorine coordination. The increased U−F bond lengths and decreased bond orders from UF{sub 2}{sup −} to UF{sub 4}{sup −} indicate that the U−F bonding becomes weaker as the oxidation state of U increases from I to III.

  5. Thermal plasma reduction of UF6

    International Nuclear Information System (INIS)

    Fincke, J.R.; Swank, W.D.; Haggard, D.C.

    1995-01-01

    This paper describes the experimental demonstration of a process for the direct plasma reduction of depleted uranium hexafluoride to uranium metal. The process exploits the large departures from equilibrium that can be achieved in the rapid supersonic expansion of a totally dissociated and partially ionized mixture of UF 6 , Ar, He, and H 2 . The process is based on the rapid condensation of subcooled uranium vapor and the relatively slow rate of back reaction between metallic uranium and HF to F 2 to reform stable fluorides. The high translational velocities and rapid cooling result in an overpopulation of atomic hydrogen which persists throughout the expansion process. Atomic hydrogen shifts the equilibrium composition by inhibiting the reformation of uranium-fluorine compounds. This process has the potential to reduce the cost of reducing UF 6 to uranium metal with the added benefit of being a virtually waste free process. The dry HF produced is a commodity which has industrial value

  6. Investigation of UF6 behavior in a fire

    International Nuclear Information System (INIS)

    Williams, W.R.

    1988-01-01

    Reactions between UF 6 and combustible gases and the potential for UF 6 -filled cylinders to rupture when exposed to fire are addressed. Although the absence of kinetic data prevents specific identification and quantification of the chemical species formed, potential reaction products resulting from the release of UF 6 into a fire include UF 4 , UO 2 F 2 , HF, C, CF 4 ,COF 2 , and short chain, fluorinated or partially fluorinated hydrocarbons. Such a release adds energy to a fire relative to normal combustion reactions. Time intervals to an assumed point of rupture for UF 6 -filled cylinders exposed to fire are estimated conservatively. Several related studies are also summarized, including a test series in which small UF 6 -filled cylinders were immersed in fire resulting in valve failures and explosive ruptures. It is concluded that all sizes of UF 6 cylinders currently in use may rupture within 30 minutes when totally immersed in a fire. For cylinders adjacent to fires, rupture of the larger cylinders appears much less likely

  7. Thermodynamic assessment of the LiF–NaF–BeF{sub 2}–ThF{sub 4}–UF{sub 4} system

    Energy Technology Data Exchange (ETDEWEB)

    Capelli, E.; Beneš, O., E-mail: ondrej.benes@ec.europa.eu; Konings, R.J.M.

    2014-06-01

    The present study describes the full thermodynamic assessment of the LiF–NaF–BeF{sub 2}–ThF{sub 4}–UF{sub 4} system which is one of the key systems considered for a molten salt reactor fuel. The work is an extension of the previously assessed LiF–NaF–ThF{sub 4}–UF{sub 4} system with addition of BeF{sub 2} which is characterized by very low neutron capture cross section and a relatively low melting point. To extend the database the binary BeF{sub 2}–ThF{sub 4} and BeF{sub 2}–UF{sub 4} systems were optimized and the novel data were used for the thermodynamic assessment of BeF{sub 2} containing ternary systems for which experimental data exist in the literature. The obtained database is used to optimize the molten salt reactor fuel composition and to assess its properties with the emphasis on the melting behaviour.

  8. Effects of molten material temperatures and coolant temperatures on vapor explosion

    Institute of Scientific and Technical Information of China (English)

    LI Tianshu; YANG Yanhua; YUAN Minghao; HU Zhihua

    2007-01-01

    An observable experiment facility for low-temperature molten materials to be dropped into water was set up in this study to investigate the mechanism of the vapor explosion. The effect of the fuel and coolant interaction(FCI) on the vapor explosion during the severe accidents of a fission nuclear reactor has been studied. The experiment results showed that the molten material temperature has an important effect on the vapor explosion behavior and pressure. The increase of the coolant temperature would decrease the pressure of the vapor explosion.

  9. Uranium isotope exchange between gaseous UF6 and solid UF5

    International Nuclear Information System (INIS)

    Yato, Yumio; Kishimoto, Yoichiro; Sasao, Nobuyuki; Suto, Osamu; Funasaka, Hideyuki

    1996-01-01

    Based on a collision model, a new rate equation is derived for uranium isotope exchange between gaseous UF 6 and solid UF 5 by considering the number of UF 5 molecules on the solid surface to be dependent on time. The reaction parameters included in the equation are determined from the experimental data and compared with the previous ones. A remarkable agreement is found between the particle sizes of UF 5 estimated from the reaction parameter and from the direct observation with an electron microscope. The rate equation given in this work fully satisfies the related mass conservation and furthermore includes explicitly the terms related to the UF 6 density and the mean size of UF 5 particles, both of which are considered to cause an important effect on the reaction. This remarkable feature facilitates the simulation studies on this reaction under various conditions. The long term behavior of a simulated exchange reaction is studied under the condition considered to be close to that in a recovery zone of the MLIS process. The result indicates that the reaction is virtually limited to the solid surface under this conditions and thus the depletion of 235 UF 5 concentration averaged over the whole UF 5 particles is not significant even after 200 h of the exchange reaction

  10. MANUFACTURE OF UF$sub 4$

    Science.gov (United States)

    Calcott, W.S.

    1959-10-13

    The manufacture of uranium tetrafluoride from urarium dioxide is described. Uranium dioxide is heated to about 500 deg C in a reactor. Anhydrous hydrogen fluoride is passed through the reactor in contact with uranium dioxide for several hours, the flow of hydrogen fluoride is discontinued, and hydrogen passed through the reactor for less than an hour. The flow of hydrogen fluoride is resumed for several hours, and then nitrogen is passed for a few minutes to expel unreacted hydrogen fluoride as water vapor. The reactor is cooled to room temperature and the uranium tetrafluoride removed.

  11. High Temperature Corrosion of Silicon Carbide and Silicon Nitride in Water Vapor

    Science.gov (United States)

    Opila, E. J.; Robinson, Raymond C.; Cuy, Michael D.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Silicon carbide (SiC) and silicon nitride (Si3N4) are proposed for applications in high temperature combustion environments containing water vapor. Both SiC and Si3N4 react with water vapor to form a silica (SiO2) scale. It is therefore important to understand the durability of SiC, Si3N4 and SiO2 in water vapor. Thermogravimetric analyses, furnace exposures and burner rig results were obtained for these materials in water vapor at temperatures between 1100 and 1450 C and water vapor partial pressures ranging from 0.1 to 3.1 atm. First, the oxidation of SiC and Si3N4 in water vapor is considered. The parabolic kinetic rate law, rate dependence on water vapor partial pressure, and oxidation mechanism are discussed. Second, the volatilization of silica to form Si(OH)4(g) is examined. Mass spectrometric results, the linear kinetic rate law and a volatilization model based on diffusion through a gas boundary layer are discussed. Finally, the combined oxidation and volatilization reactions, which occur when SiC or Si3N4 are exposed in a water vapor-containing environment, are presented. Both experimental evidence and a model for the paralinear kinetic rate law are shown for these simultaneous oxidation and volatilization reactions.

  12. Melting temperature, vapor density, and vapor pressure of molybdenum pentafluoride

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Jr, R F; Douglas, T B [National Bureau of Standards, Washington, D.C. (USA). Inst. for Materials Research

    1977-12-01

    A sample of MoF/sub 5/ was prepared by reaction of MoF/sub 6/(g) and Mo(c). Melting curves of temperature against time established the melting temperature at zero impurity to be 318.85 K, the enthalpy of fusion to be 6.1 kJ mol/sup -1/ (+ - 5 per cent), and the cryoscopic impurity of the sample to be 0.15 mole per cent. In the presence of MoF/sub 6/(g) which was added to suppress disproportionation, the vapor density of MoF/sub 5/ over the liquid was measured by the transpiration method at 343, 363, and 383 K, the total MoF/sub 5/ that evaporated being determined by permanganate titration. The total vapor pressure of MoF/sub 5/ oligomers over the liquid was measured by a simple static method at 373 and 392 K, while melting temperatures were taken alternately to monitor possible contamination of the sample. Although the vapor pressures were adjusted for disproportionation, solution of MoF/sub 6/ in MoF/sub 5/ (1), and wall adsorption of MoF/sub 6/ their percentage uncertainty is probably several times that of the vapor densities. A combination of the two properties indicates the average extent of association of the saturated vapor to be near 2, which is the value for the dimer species (MoF/sub 5/)/sub 2/.

  13. Water vapor concentration dependence and temperature dependence of Li mass loss from Li{sub 2}TiO{sub 3} with excess Li and Li{sub 4}SiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Shimozori, Motoki [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Katayama, Kazunari, E-mail: kadzu@nucl.kyushu-u.ac.jp [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Hoshino, Tsuyoshi [Breeding Functional Materials Development Group, Department of Blanket Systems Research, Rokkasho Fusion Institute, Sector of Fusion Research and Development, Japan Atomic Energy Agency, 2-166 Obuch, Omotedate, Rokkasho-mura, Kamikita-gun, Aomori 039-3212 (Japan); Ushida, Hiroki; Yamamoto, Ryotaro; Fukada, Satoshi [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan)

    2015-10-15

    Highlights: • Li mass loss from Li{sub 2.11}TiO{sub 3} increased proportionally to water vapor pressure. • Li mass loss from Li{sub 2.11}TiO{sub 3} at 600 °C was significantly smaller than expected. • Differences of Li mass loss behavior from Li{sub 2.11}TiO{sub 3} and Li{sub 4}SiO{sub 4} were shown. - Abstract: In this study, weight reduction of Li{sub 2}TiO{sub 3} with excess Li and Li{sub 4}SiO{sub 4} at elevated temperatures under hydrogen atmosphere or water vapor atmosphere was investigated. The Li mass loss for the Li{sub 2}TiO{sub 3} at 900 °C was 0.4 wt% under 1000 Pa H{sub 2} atmosphere and 1.5 wt% under 50 Pa H{sub 2}O atmosphere. The Li mass loss for the Li{sub 2}TiO{sub 3} increased proportionally to the water vapor pressure in the range from 50 to 200 Pa at 900 °C and increased with increasing temperature from 700 to 900 °C although Li mass loss at 600 °C was significantly smaller than expected. It was found that water vapor concentration dependence and temperature dependence of Li mass loss for the Li{sub 2}TiO{sub 3} and the Li{sub 4}SiO{sub 4} used in this work were quite different. Water vapor is released from the ceramic breeder materials into the purge gas due to desorption of adsorbed water and water formation reaction. The released water vapor possibly promotes Li mass loss with the formation of LiOH on the surface.

  14. Anisotropy of the fluorine chemical shift tensor in UF6

    International Nuclear Information System (INIS)

    Rigny, P.

    1965-04-01

    An 19 F magnetic resonance study of polycrystalline UF 6 is presented. The low temperature complex line can be analyzed as the superposition of two distinct lines, which is attributed to a distortion of the UF 6 octahedron in the solid. The shape of the two components is studied. Their width is much larger than the theoretical dipolar width, and must be explained by large anisotropies of the fluorine chemical shift tensors. The resulting shape functions of the powder spectra are determined. The values of the parameters of the chemical shift tensors yield estimates of the characters of the U-F bonds, and this gives some information on the ground state electronic wave function of the UF 6 molecule in the solid. (author) [fr

  15. Application of the HGSYSTEM/UF6 model to simulate atmospheric dispersion of UF6 releases from uranium enrichment plants

    International Nuclear Information System (INIS)

    Goode, W.D. Jr.; Bloom, S.G.; Keith, K.D. Jr.

    1995-01-01

    Uranium hexafluoride is a dense, reactive gas used in Gaseous Diffusion Plants (GDPs) to make uranium enriched in the 235 U isotope. Large quantities of UF 6 exist at the GDPs in the form of in-process gas and as a solid in storage cylinders; smaller amounts exist as hot liquid during transfer operations. If liquid UF 6 is released to the environment, it immediately flashes to a solid and a dense gas that reacts rapidly with water vapor in the air to form solid particles of uranyl fluoride and hydrogen fluoride gas. Preliminary analyses were done on various accidental release scenarios to determine which scenarios must be considered in the safety analyses for the GDPS. These scenarios included gas releases due to failure of process equipment and liquid/gas releases resulting from a breach of transfer piping from a cylinder. A major goal of the calculations was to estimate the response time for mitigating actions in order to limit potential off-site consequences of these postulated releases. The HGSYSTEM/UF 6 code was used to assess the consequences of these release scenarios. Inputs were developed from release calculations which included two-phase, choked flow followed by expansion to atmospheric pressure. Adjustments were made to account for variable release rates and multiple release points. Superpositioning of outputs and adjustments for exposure time were required to evaluate consequences based on health effects due to exposures to uranium and HF at a specific location

  16. Extremely low temperature behaviour of the thermodynamical properties of gaseous UF6 under an exact quantum approach

    International Nuclear Information System (INIS)

    Amarante, J.A.A. do.

    1979-10-01

    The thermodynamic functions of molecules of type XF 6 are calculated under an exact quantum-mechanical approach, which also yields general expressions valid for other types of molecules. The formalism is used to analyse the behavior of gaseous UF 6 at very low temperatures (around and below 1 0 K), where symmetry effects due to Pauli principle lead to results which are very markedly different from those obtained with the semi-classical approximation. It is shown that this approximation becomes sufficiently accurate only for temperatures about ten times the rotational temperature. (Author) [pt

  17. Influence of UF4 physico-chemical properties on the assessment of the chronic exposure to this compound

    International Nuclear Information System (INIS)

    Ansoborlo, E.; Chalabreysse, J.

    1990-01-01

    A method was developed in order to assess uranium exposure hazards at work stations based on the industrial experience acquired by Comurhex Malvesi at Narbonne. Applied to uranium tetrafluoride (UF 4 ) the method involves 4 steps: 1. characterization of the industrial compound, including its physico-chemical properties (density, surface area, X-ray spectrum and uranium enrichment); 2. assessment of work station concentrations and particle size distribution (AMAD); 3. In vitro biological solubility with different synthetic fluids such as Gamble solutions with different gases or compounds added (oxygen or superoxide ions O 2 - ) in order to determine the solubility class D, W or Y; 4. workers' monitoring by routine measurements of urinary excretion completed, if necessary, by fecal excretion and γ-spectrometry. Results and present data on UF 4 are presented. 3 tabs., 4 figs [fr

  18. 2D modelling of a UF6 container in a fire

    International Nuclear Information System (INIS)

    Duret, B.; Seiler, J.M.

    1993-01-01

    We present some results on 2D thermal modelisation of the behaviour of UF6 in a fire. A cylindrical container is engulfed by a high temperature space where the heat transfer is expected to occur by radiation only. During the first minutes, we assume that the thermal resistance is between the external wall and the UF6 solid, the heat transfer can be split up into three kinds: 1) conduction to solid UF6 through a contact surface. 2) radiative transfer. 3) gas layer with a small heat conductance. This thermal resistance is initially determined by the UF6 filling type, shape and also is time dependant by thermal dilatation effects. On the onset of liquifying the heat transfer increases because of the larger liquid exchange. The liquid and boiling heat flow is then calculated by a model on the basis of classical correlations in vertical cavities. Numerical evaluations have been performed with a finite element model using: ANSYS. With a realistic hypothesis, the effect of the following parameters is estimated: thermal conductivity of UF6 solid, contact surface fraction, UF6 emissivity, gas gap thickness, liquid UF6 wall exchange, solid liquid transition criteria, non condensation factor k. (J.P.N.)

  19. Assessment of UF6 Equation of State

    Energy Technology Data Exchange (ETDEWEB)

    Brady, P; Chand, K; Warren, D; Vandersall, J

    2009-02-11

    A common assumption in the mathematical analysis of flows of compressible fluids is to treat the fluid as a perfect gas. This is an approximation, as no real fluid obeys the perfect gas relationships over all temperature and pressure conditions. An assessment of the validity of treating the UF{sub 6} gas flow field within a gas centrifuge with perfect gas relationships has been conducted. The definition of a perfect gas is commonly stated in two parts: (1) the gas obeys the thermal equation of state, p = {rho}RT (thermally perfect), and, (2) the gas specific heats are constant (calorically perfect). Analysis indicates the thermally perfect assumption is valid for all flow conditions within the gas centrifuge, including shock fields. The low operating gas pressure is the primary factor in the suitability of the thermally perfect equation of state for gas centrifuge computations. UF{sub 6} is not calorically perfect, as the specific heats vary as a function of temperature. This effect is insignificant within the bulk of the centrifuge gas field, as gas temperatures vary over a narrow range. The exception is in the vicinity of shock fields, where temperature, pressure, and density gradients are large, and the variation of specific heats with temperature should be included in the technically detailed analyses. Results from a normal shock analysis incorporating variable specific heats is included herein, presented in the conventional form of shock parameters as a function of inlet Mach Number. The error introduced by assuming constant specific heats is small for a nominal UF{sub 6} shock field, such that calorically perfect shock relationships can be used for scaling and initial analyses. The more rigorous imperfect gas analysis should be used for detailed analyses.

  20. Vaporization of tungsten-metal in steam at high temperatures

    International Nuclear Information System (INIS)

    Greene, G.A.; Finfrock, C.C.

    2000-01-01

    The vaporization of tungsten from the APT spallation target dominates the radiological source term for unmitigated target overheating accidents. Chemical reactions of tungsten with steam which persist to tungsten temperatures as low as 800 C result in the formation of a hydrated tungsten-oxide which has a high vapor pressure and is readily convected in a flowing atmosphere. This low-temperature vaporization reaction essentially removes the oxide film that forms on the tungsten-metal surface as soon as it forms, leaving behind a fresh metallic surface for continued oxidation and vaporization. Experiments were conducted to measure the oxidative vaporization rates of tungsten in steam as part of the effort to quantify the MT radiological source term for severe target accidents. Tests were conducted with tungsten rods (1/8 inch diameter, six inches long) heated to temperatures from approximately 700 C to 1350 C in flowing steam which was superheated to 140 C. A total of 19 experiments was conducted. Fifteen tests were conducted by RF induction heating of single tungsten rods held vertical in a quartz glass retort. Four tests were conducted in a vertically-mounted tube furnace for the low temperature range of the test series. The aerosol which was generated and transported downstream from the tungsten rods was collected by passing the discharged steam through a condenser. This procedure insured total collection of the steam along with the aerosol from the vaporization of the rods. The results of these experiments revealed a threshold temperature for tungsten vaporization in steam. For the two tests at the lowest temperatures which were tested, approximately 700 C, the tungsten rods were observed to oxidize without vaporization. The remainder of the tests was conducted over the temperature range of 800 C to 1350 C. In these tests, the rods were found to have lost weight due to vaporization of the tungsten and the missing weight was collected in the downstream condensate

  1. Mechanisms controlling temperature dependent mechanical and electrical behavior of SiH4 reduced chemically vapor deposited W

    International Nuclear Information System (INIS)

    Joshi, R.V.; Prasad, V.; Krusin-Elbaum, L.; Yu, M.; Norcott, M.

    1990-01-01

    The effects of deposition temperature on growth, composition, structure, adhesion properties, stress, and resistivity of chemically vapor deposited W deposited purely by SiH 4 reduction of WF 6 are discussed. At lower deposition temperatures, due to incomplete Si reduction reaction, a small amount of Si is incorporated in the film. This elemental Si in W is responsible for the observed high stresses and high resistivities over a wide temperature range. With the increase in the deposition temperature, the conversion of incorporated Si as well as the initial Si reduction are taking place, stimulating increased grain growth and thereby relieving stress and reducing resistivity. The optimum values for stress and resistivity are achieved around 500 degree C, as Si content is at its minimum. At higher temperatures the reaction between residual Si and W, is the prime cause of resistivity increase

  2. Electrochemical separation of uranium in the molten system LiF-NaF-KF-UF4

    Science.gov (United States)

    Korenko, M.; Straka, M.; Szatmáry, L.; Ambrová, M.; Uhlíř, J.

    2013-09-01

    This article is focused on the electrochemical investigation (cyclic voltammetry and related studies) of possible reduction of U4+ ions to metal uranium in the molten system LiF-NaF-KF(eut.)-UF4 that can provide basis for the electrochemical extraction of uranium from molten salts. Two-step reduction mechanism for U4+ ions involving one electron exchange in soluble/soluble U4+/U3+ system and three electrons exchange in the second step were found on the nickel working electrode. Both steps were found to be reversible and diffusion controlled. Based on cyclic voltammetry, the diffusion coefficients of uranium ions at 530 °C were found to be D(U4+) = 1.64 × 10-5 cm2 s-1 and D(U3+) 1.76 × 10-5 cm2 s-1. Usage of the nickel spiral electrode for electrorefining of uranium showed fairly good feasibility of its extraction. However some oxidant present during the process of electrorefining caused that the solid deposits contained different uranium species such as UF3, UO2 and K3UO2F5.

  3. Investigation of technology for the monitoring of UF6 mass flow in UF6 streams diluted with H2

    International Nuclear Information System (INIS)

    Baker, O.J.; Cooley, J.N.; Hewgley, W.A.; Moran, B.W.; Swindle, D.W. Jr.

    1986-12-01

    The applicability, availability, and effectiveness of gas flow meters are assessed as a means for verifying the mass flows of pure UF 6 streams diluted with a carrier gas. The initial survey identified the orifice, pitot tube, thermal, vortex shedding, and vortex precession (swirl) meters as promising for the intended use. Subsequent assessments of these flow meters revealed that two - the orifice meter and the pitot tube meter - are the best choices for the proposed applications: the first is recommended for low velocity gas, small diameter piping; the latter, for high velocity gas, large diameter piping. Final selection of the gas flow meters should be based on test loop evaluations in which the proposed meters are subjected to gas flows, temperatures, and pressures representative of those expected in service. Known instruments are evaluated that may be applicable to the measurement of uranium or UF 6 concentration in a UF 6 - H 2 process stream at an aerodynamic enrichment plant. Of the six procedures evaluated, four have been used for process monitoring in a UF 6 environment: gas mass spectrometry, infrared-ultraviolet-visible spectrophotometry, gas chromatography, and acoustic gas analysis. The remaining two procedures, laser fluorimetry and atomic absorption spectroscopy, would require significant development work before they could be used for process monitoring. Infrared-ultravioloet-visible spectrophotometry is judged to be the best procedure currently available to perform the required measurement

  4. Fluorescence from gaseous UF/sub 6/ excited by a near-UV dye laser. [Decay time,quenching rate,room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Benetti, P [Pavia Univ. (Italy); Cubeddu, R; Sacchi, C A; Svelto, O; Zaraga, F [Politecnico di Milano (Italy)

    1976-06-01

    Preliminary data are reported on the visible fluorescence of gaseous UF/sub 6/ excited by a dye laser at 374 nm. A decay time of 500 ns at p = 0 and a quenching rate of 5.7 x 10/sup -12/cm/sup 3/molec/sup -1/s/sup -1/ have been measured at room temperature.

  5. Reduction of UF4 to U-metal

    International Nuclear Information System (INIS)

    Namkung, H.; Min, B.T.; Kim, J.S.; Whang, S.C.

    1982-01-01

    In the second years of study for the production of the metallic uranium with reactors which can produce 1 Kg and 4 Kg U-metal, various factors on the yield of U-metal and the leaching condition for uranium recovery with nitric acid are examined. The jolter has been used for the charging with liner (MgF 2 ) while the hand-tamping method for the filling of reaction mixtures (UF 4 -Mg) in the reactor, and their average densities are 1.23g/cc and 2.90g/cc, respectively. The various effects on the yield such as magnesium excess, furnace control temperatue, charge densities of liner and reaction mixtures, have been studied but the yields of crude metal production are in the wide range from 93 % down to about 65 %. Generally, six percent magnesium excess produced higher yields than did either 2 or 10 percent excess. The leaching condition for the uranium recovery from slag are also investigated with dilute nitric acid (3-6N) as well as higher concentrated nitric acid (9.5N) but the leaching yields are same in either solution. Uranium recovery from the slag is very effective with dilute nitric acid (3N) leaching for less than one hour at 60degC. (Author)

  6. Analysis of accidental UF6 releases

    International Nuclear Information System (INIS)

    Fan Yumao; Tan Rui; Gao Qifa

    2012-01-01

    As interim substance in the nuclear fuel enrichment process, Uranium Hexafluoride (UF 6 ) is widely applied in nuclear processing, enrichment and fuel fabrication plants. Because of its vivid chemical characteristics and special radiological hazard and chemical toxicity, great attention must be paid to accident of UF 6 leakage. The chemical reactions involved in UF 6 release processes were introduced, therewith potential release styles, pathways and characteristics of diffusion were analyzed. The results indicated that the accidental release process of UF 6 is not a simple passive diffusion. So, specific atmospheric diffusion model related to UF 6 releases need be used in order to analyze and evaluate accurately the accidental consequences. (authors)

  7. Chemical exchange between UF6 and UF6- ion in anhydrous hydrofluoric acid

    International Nuclear Information System (INIS)

    Chatelet, J.; Luce, M.; Plurien, P.; Rigny, P.

    1975-01-01

    The chemical exchange between UF 6 and the UF 6 - ion is of potential interest for the separation of U isotopes. In this paper, results concerning the value of the separation factor and the kinetics of the homogeneous exchange are given [fr

  8. Vapor pressures and standard molar enthalpies, entropies, and Gibbs free energies of sublimation of 2,4- and 3,4-dinitrobenzoic acids

    International Nuclear Information System (INIS)

    Vecchio, Stefano; Brunetti, Bruno

    2009-01-01

    The vapor pressures of the solid and liquid 2,4- and 3,4-dinitrobenzoic acids were determined by torsion-effusion and thermogravimetry under both isothermal and non-isothermal conditions, respectively. From the temperature dependence of vapor pressure derived by the experimental torsion-effusion and thermogravimetry data the molar enthalpies of sublimation Δ cr g H m 0 ( ) and vaporization Δ l g H m 0 ( ) were determined, respectively, at the middle of the respective temperature intervals. The melting temperatures and the molar enthalpies of fusion of these compounds were measured by d.s.c. Finally, the results obtained by all the methods proposed were corrected at the reference temperature of 298.15 K using the estimated heat capacity differences between gas and liquid for vaporization experiments and the estimated heat capacity differences between gas and solid for sublimation experiments. Therefore, the averages of the standard (p o = 0.1 MPa) molar enthalpies, entropies and Gibbs free energies of sublimation at 298.15 K, have been derived.

  9. High-temperature vaporization behavior of oxygen-deficient thoria

    International Nuclear Information System (INIS)

    Ackermann, R.J.; Tetenbaum, M.

    1979-01-01

    The experimental results of the present study on the vaporization behavior of oxygen-deficient thoria are directed toward a more precise and detailed study of the lower phase boundary (l.p.b.) and congruently vaporizing composition (c.v.c), and intermediate compositions, and the corresponding oxygen potentials and total pressure at temperatures above 2000K. The l.p.b. and c.v.c. values were found to fit an equation of the form log x = A + (B/T), where x is the stoichiometric defect in ThO 2 -x. Oxygen potentials corresponding to the l.p.b. and c.v.c. have been estimated from vapor pressures and thermodynamic data. A very sharp decrease in oxygen potential occurs when thoria isreduced only slightly from the stoichiometric composition. In the temperature range from 2400 to 2655 K, the oxygen partial pressure dependency of x in ThO 2 -x was found to be approximately proportional to PO 2 - 1 /4to PO 2 - 1 /. The small extent of reduction over a wide range of oxygen potentials at these temperatures is a clear illustration of the higher stability of the ThO 2 -x phase compared with that of UO 2 -x. Values of ΔHO 2 and ΔSO 2 have been estimated for selected compositions from the dependence of the measured oxygen potential on temperature. Estimates of the standard free energy of formation of bivariant ThO 2 -x compositions have been made. A substantial increase in the total pressure of thorium-bearing species occurs when stoichiometric thoria is reduced toward the lower phase boundary. (orig.) [de

  10. A Temperature Window for the Synthesis of Single-Walled Carbon Nanotubes by Catalytic Chemical Vapor Deposition of CH4over Mo2-Fe10/MgO Catalyst

    Directory of Open Access Journals (Sweden)

    Yu Ouyang

    2009-01-01

    Full Text Available Abstract A temperature window for the synthesis of single-walled carbon nanotubes by catalytic chemical vapor deposition of CH4over Mo2-Fe10/MgO catalyst has been studied by Raman spectroscopy. The results showed that when the temperature is lower than 750 °C, there were few SWCNTs formed, and when the temperature is higher than 950 °C, mass amorphous carbons were formed in the SWCNTs bundles due to the self-decomposition of CH4. The temperature window of SWCNTs efficient growth is between 800 and 950 °C, and the optimum growth temperature is about 900 °C. These results were supported by transmission electron microscope images of samples formed under different temperatures. The temperature window is important for large-scale production of SWCNTs by catalytic chemical vapor deposition method.

  11. Electron affinity of UF6. Final report, March 1, 1976--June 30, 1977

    International Nuclear Information System (INIS)

    Rothe, E.W.

    1977-06-01

    Ionization reactions are observed in crossed molecular beams, usually of thermal energy, alkalis and MoF 6 , WF 6 and UF 6 . Previous studies have indicated large electron affinities for these hexafluorides, and this is confirmed here. Ionization at thermal energies proceeds with the alkali dimers, A 2 , for all three hexafluorides, but with alkali atoms, A, only for UF 6 . Several ionization paths are observed, allowing the deduction of molecular energies. A few experiments are done with eV-range beams. Lower limits for the elecron affinities are 4.5, 3.3, 4.9, 4.3 and 1.9 eV for MoF 6 , MoF 5 , WF 6 , UF 6 and UF 5 , respectively. Possible mechanisms are discussed

  12. Numerical modeling of the vertical hydrofluorination zone in the moving bed furnace for the production of UF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Jourde, J.; Patisson, F.; Ablitzer, D. [Ecole des Mines, Nancy (France). Lab. de Science et Genie des Materiaux Metalliques; Houzelot, J.L. [Ecole des Mines, Nancy (France). Lab. des Sciences du Genie Chimique

    1996-12-31

    Uranium tetrafluoride UF{sub 4} is produced in the moving bed furnace, a reactor in which solid- and gas counterflow. Due to the highly exothermic nature of the chemical reactions involved, the-reactor operation requires a careful temperature control. To provide operators with an appropriate tool for the predictive simulation, optimization and control of the process an overall numerical model of the furnace has been developed. This article describes the part of the model concerning the vertical hydrofluorination zone. The differential equations representing the mass, energy and momentum balances are solved using the finite volume method. The physicochemical parameters necessary for the calculation are detailed. The rate of the main reaction, the hydrofluorination of UO{sub 2}, has been determined with the aid of a specific kinetic model. The computed parameters, namely the temperature and solid and gas compositions, are visualized in the form of isovalue maps. The initial results reveal the influence of a thermodynamic limitation of the reaction at temperatures higher than 650 K. (author)

  13. Numerical modeling of the vertical hydrofluorination zone in the moving bed furnace for the production of UF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Jourde, J; Patisson, F; Ablitzer, D [Ecole des Mines, Nancy (France). Lab. de Science et Genie des Materiaux Metalliques; Houzelot, J L [Ecole des Mines, Nancy (France). Lab. des Sciences du Genie Chimique

    1997-12-31

    Uranium tetrafluoride UF{sub 4} is produced in the moving bed furnace, a reactor in which solid- and gas counterflow. Due to the highly exothermic nature of the chemical reactions involved, the-reactor operation requires a careful temperature control. To provide operators with an appropriate tool for the predictive simulation, optimization and control of the process an overall numerical model of the furnace has been developed. This article describes the part of the model concerning the vertical hydrofluorination zone. The differential equations representing the mass, energy and momentum balances are solved using the finite volume method. The physicochemical parameters necessary for the calculation are detailed. The rate of the main reaction, the hydrofluorination of UO{sub 2}, has been determined with the aid of a specific kinetic model. The computed parameters, namely the temperature and solid and gas compositions, are visualized in the form of isovalue maps. The initial results reveal the influence of a thermodynamic limitation of the reaction at temperatures higher than 650 K. (author)

  14. Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.

    Science.gov (United States)

    Horn, Hans W; Swope, William C; Pitera, Jed W

    2005-11-15

    The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.

  15. Optimizing UF Cleaning in UF-SWRO System Using Red Sea Water

    KAUST Repository

    Bahshwan, Mohanad

    2012-07-01

    Increasing demand for fresh water in arid and semi-arid areas, similar to the Middle East, pushed for the use of seawater desalination techniques to augment freshwater. Seawater Reverse Osmosis (SWRO) is one of the techniques that have been commonly used due to its cost effectiveness. Recently, the use of Ultrafiltration (UF) was recommended as an effective pretreatment for SWRO membranes, as opposed to conventional methods (i.e. sand filtration). During UF operation, intermittent cleaning is required to remove particles and contaminants from the membrane\\'s surface and pores. The different cleaning steps consume chemicals and portion of the product water, resulting in a decrease in the overall effectiveness of the process and hence an increase in the production cost. This research focused on increasing the plant\\'s efficiency through optimizing the cleaning protocol without jeopardizing the effectiveness of the cleaning process. For that purpose, the design of experiment (DOE) focused on testing different combinations of these cleaning steps while all other parameters (such as filtration flux or backwash flux) remained constant. The only chemical used was NaOCI during the end of each experiment to restore the trans-membrane pressure (TMP) to its original state. Two trains of Dow™ Ultrafiltration SFP-2880 were run in parallel for this study. The first train (named UF1) was kept at the manufacturer\\'s recommended cleaning steps and frequencies, while the second train (named UF2) was varied according to the DOE. The normalized final TMP was compared to the normalized initial TMP to measure the fouling rate of the membrane at the end of each experiment. The research was supported by laboratory analysis to investigate the cause of the error in the data by analyzing water samples collected at different locations. Visual inspection on the results from the control unit showed that the data cannot be reproduced with the current feed water quality. Statistical analysis

  16. pVT-Second Virial Coefficients B(T ), Viscosity η(T ), and Self-Diffusion ρD(T) of the Gases: BF3, CF4, SiF4, CCl4, SiCl4, SF6, MoF6, WF6, UF6, C(CH3)4, and Si(CH3)4 Determined by Means of an Isotropic Temperature-Dependent Potential

    Science.gov (United States)

    Zarkova, L.; Hohm, U.

    2002-03-01

    We present results on self-consistent calculations of second pVT-virial coefficients B(T), viscosity data η(T), and diffusion coefficients ρD(T) for eleven heavy globular gases: boron trifluoride (BF3), carbon tetrafluoride (CF4), silicon tetrafluoride (SiF4), carbon tetrachloride (CCl4), silicon tetrachloride (SiCl4), sulfur hexafluoride (SF6), molybdenum hexafluoride (MoF6), tungsten hexafluoride (WF6), uranium hexafluoride (UF6), tetramethyl methane (C(CH3)4, TMM), and tetramethyl silane (Si(CH3)4, TMS). The calculations are performed mainly in the temperature range between 200 and 900 K by means of isotropic n-6 potentials with temperature-dependent separation rm(T) and potential well depth ɛ(T). The potential parameters at T=0 K (ɛ, rm, n) and the enlargement of the first level radii δ are obtained solving an ill-posed problem of minimizing the squared deviations between experimental and calculated values normalized to their relative experimental error. The temperature dependence of the potential is obtained as a result of the influence of vibrational excitation on binary interactions. This concept of the isotropic temperature-dependent potential (ITDP) is presented in detail where gaseous SF6 will serve as an example. The ITDP is subsequently applied to all other gases. This approach and the main part of the results presented here have already been published during 1996-2000. However, in some cases the data are upgraded due to the recently improved software (CF4, SF6) and newly found experimental data (CF4, SiF4, CCl4, SF6).

  17. Computational Fluid Dynamics Model for Saltstone Vault 4 Vapor Space

    International Nuclear Information System (INIS)

    Lee, Si Young

    2005-01-01

    Computational fluid dynamics (CFD) methods have been used to estimate the flow patterns for vapor space inside the Saltstone Vault No.4 under different operating scenarios. The purpose of this work is to examine the gas motions inside the vapor space under the current vault configurations. A CFD model took three-dimensional transient momentum-energy coupled approach for the vapor space domain of the vault. The modeling calculations were based on prototypic vault geometry and expected normal operating conditions as defined by Waste Solidification Engineering. The modeling analysis was focused on the air flow patterns near the ventilated corner zones of the vapor space inside the Saltstone vault. The turbulence behavior and natural convection mechanism used in the present model were benchmarked against the literature information and theoretical results. The verified model was applied to the Saltstone vault geometry for the transient assessment of the air flow patterns inside the vapor space of the vault region using the boundary conditions as provided by the customer. The present model considered two cases for the estimations of the flow patterns within the vapor space. One is the reference baseline case. The other is for the negative temperature gradient between the roof inner and top grout surface temperatures intended for the potential bounding condition. The flow patterns of the vapor space calculated by the CFD model demonstrate that the ambient air comes into the vapor space of the vault through the lower-end ventilation hole, and it gets heated up by the Benard-cell type circulation before leaving the vault via the higher-end ventilation hole. The calculated results are consistent with the literature information

  18. The vaporization enthalpy and vapor pressure of S (+)-methamphetamine at T = 298.15 K by correlation gas chromatography

    International Nuclear Information System (INIS)

    Thornton, Melissa; Gobble, Chase; Chickos, James

    2014-01-01

    Highlights: • The vaporization enthalpy of (d)-methamphetamine was measured. • The vapor pressure of (d)-methamphetamine as a function of temperature was evaluated. • The vapor pressure of 4-benzylpiperidine as a function of temperature was evaluated. - Abstract: The vaporization enthalpy and vapor pressure of S (+)-methamphetamine is evaluated by correlation-gas chromatography. A vaporization enthalpy of (58.7 ± 4.3) kJ · mol −1 and a vapor pressure, p = (38 ± 9) Pa has been obtained using a variety of secondary aliphatic amines as standards. In addition, equations describing the vapor pressure temperature dependence are provided for standards and S (+)-methamphetamine covering the temperature range from T = 298.15 K to the boiling temperature. Boiling temperatures are reproduced within an interval of 8 K or less

  19. Electrochemical separation of uranium in the molten system LiF–NaF–KF–UF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Korenko, M., E-mail: Michal.Korenko@savba.sk [Fluorine Chemistry Department, Nuclear Research Institute (NRI) Řež Plc., Husinec-Řež 130, CZ-250 68 (Czech Republic); Department of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 36 Bratislava (Slovakia); Straka, M.; Szatmáry, L. [Fluorine Chemistry Department, Nuclear Research Institute (NRI) Řež Plc., Husinec-Řež 130, CZ-250 68 (Czech Republic); Ambrová, M. [Institute of Inorganic Chemistry, Technology and Materials, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava (Slovakia); Uhlíř, J. [Fluorine Chemistry Department, Nuclear Research Institute (NRI) Řež Plc., Husinec-Řež 130, CZ-250 68 (Czech Republic)

    2013-09-15

    This article is focused on the electrochemical investigation (cyclic voltammetry and related studies) of possible reduction of U{sup 4+} ions to metal uranium in the molten system LiF–NaF–KF(eut.)–UF{sub 4} that can provide basis for the electrochemical extraction of uranium from molten salts. Two-step reduction mechanism for U{sup 4+} ions involving one electron exchange in soluble/soluble U{sup 4+}/U{sup 3+} system and three electrons exchange in the second step were found on the nickel working electrode. Both steps were found to be reversible and diffusion controlled. Based on cyclic voltammetry, the diffusion coefficients of uranium ions at 530 °C were found to be D(U{sup 4+}) = 1.64 × 10{sup −5} cm{sup 2} s{sup −1} and D(U{sup 3+}) 1.76 × 10{sup −5} cm{sup 2} s{sup −1}. Usage of the nickel spiral electrode for electrorefining of uranium showed fairly good feasibility of its extraction. However some oxidant present during the process of electrorefining caused that the solid deposits contained different uranium species such as UF{sub 3}, UO{sub 2} and K{sub 3}UO{sub 2}F{sub 5}.

  20. Vapor pressures and vapor compositions in equilibrium with hypostoichiometric plutonium dioxide at high temperatures

    International Nuclear Information System (INIS)

    Green, D.W.; Fink, J.K.; Leibowitz, L.

    1982-01-01

    Vapor pressures and vapor compositions have been calculated for 1500 less than or equal to T less than or equal to 4000 0 K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model extended into the liquid region to obtain the partial pressures of O 2 , O, Pu, PuO and PuO 2 . The calculated oxygen pressures increase very rapidly as stoichiometry is approached. At least part of this increase is a consequence of the exclusion of Pu 6 + from the oxygen-potential model. No reliable method was found to estimate the importance of this ion. As a result of large oxygen potentials at high temperatures, extremely high total pressures that produced unreasonably high vapor densities were calculated. The highest temperature was therefore limited to 400 K, and the range of oxygen-to-metal ratios was limited to 1.994 to 1.70. These calculations show that vapor in equilibrium with hypostoichiometric plutonium dioxide is poorly approximated as PuO 2 for most of the temperture and composition range of interest. The vapor is much more oxygen-rich than the condensed phase. Implications for the (U,Pu)O/sub 2-x/ system are discussed

  1. Microscale interfacial behavior at vapor film collapse on high-temperature particle surface

    International Nuclear Information System (INIS)

    Abe, Yutaka; Tochio, Daisuke

    2009-01-01

    It has been pointed out that vapor film on a premixed high-temperature droplet surface should be collapsed to trigger vapor explosion. Thus, it is important to clarify the micromechanism of vapor film collapse behavior for the occurrence of vapor explosion. In the present study, microscale vapor-liquid interface behavior upon vapor film collapse caused by an external pressure pulse is experimentally observed and qualitatively analyzed. In the analytical investigation, interfacial temperature and interface movement were estimated with heat conduction analysis and visual data processing technique. Results show that condensation can possibly occur at the vapor-liquid interface when the pressure pulse arrived. That is, this result indicates that the vapor film collapse behavior is dominated not by fluid motion but by phase change. (author)

  2. Method for selectively removing fluorine and fluorine-containing contaminants from gaseous UF/sub 6/. [ClF/sub 3/

    Science.gov (United States)

    Jones, R.L.; Otey, M.G.; Perkins, R.W.

    1980-11-24

    This invention is a method for effecting preferential removal and immobilization of certain gaseous contaminants from gaseous UF/sub 6/. The contaminants include fluorine and fluorides which are more reactive with CaCO/sub 3/ than is UF/sub 6/. The method comprises contacting the contaminant-carrying UF/sub 6/ with particulate CaCO/sub 3/ at a temperature effecting reaction of the contaminant and the CaCO/sub 3/.

  3. Rupture of Model 48Y UF6 cylinder and release of uranium hexafluoride, Sequoyah Fuels Facility, Gore, Oklahoma, January 4, 1986. Volume 1

    International Nuclear Information System (INIS)

    1986-02-01

    At 11:30 a.m. on January 4, 1986, a Model 48Y UF 6 cylinder filled with uranium hexafluoride (UF 6 ) ruptured while it was being heated in a steam chest at the Sequoyah Fuels Conversion Facility near Gore, Oklahoma. One worker died because he inhaled hydrogen fluoride fumes, a reaction product of UF 6 and airborne moisture. Several other workers were injured by the fumes, but none seriously. Much of the facility complex and some offsite areas to the south were contaminated with hydrogen fluoride and a second reaction product, uranyl fluoride. The interval of release was approximately 40 minutes. The cylinder, which had been overfilled, ruptured while it was being heated because of the expansion of UF 6 as it changed from the solid to the liquid phase. The maximum safe capacity for the cylinder is 27,560 pounds of product. Evidence indicates that it was filled with an amount exceeding this limit. 18 figs

  4. UV dissociation of vibrationally excited UF6

    International Nuclear Information System (INIS)

    Alexandre, M.; Clerc, M.; Gagnon, R.; Gilbert, M.; Isnard, P.; Nectoux, P.; Rigny, P.; Weulersse, J.M.

    1983-01-01

    Before application of laser photodissociation of UF 6 to the separation of uranium isotopes becomes practical, isotopic selectivity should be optimized. We present here results on the cross sections involved in the irradiation of UF 6 simultaneously with infrared and ultraviolet lasers, as a function of wavelengths, fluence and temperature (at 293 K and 105 K, in an adiabatic expansion). The experiment uses a Nd 3+ YAG pumped lithium niobate optical parametric oscillator as a tunable 16 μ light source. Energies of the order of 1 mJ can be obtained with linewidths smaller than 0.1 cm - . The UV source used is based on ND 3+ YAG pumped dye laser and various frequency mixing schemes. At low temperature the frequency variation of the absorbed infrared energy per molecule depends markedly on the IR fluence phisub(IR) with a maximum value varying as phisub(IR)sup(-1/2) and a frequency extension far beyond the low level absorption spectrum. The absorbed vibrational energy leads to a change in the UV cross section comparable with the effect of a rise in temperature. Using this a model is put forward to express the isotopic selectivity 235 U/ 238 U as a function of UV wavelength and IR irradiation conditions. Experimental results agree with this model, and yield to maximum selectivity close to two [fr

  5. Investigation of technology for monitoring UF6 mass flow

    International Nuclear Information System (INIS)

    Cooley, J.N.; Moran, B.W.; Swindle, D.W. Jr.

    1987-06-01

    The applicability of gas flow meters, in-line enrichment monitors, and instruments for measuring uranium or UF 6 concentrations in process streams as a means for verifying declared plant throughput have been investigated. The study was performed to assist the International Atomic Energy Agency in the development of an effective international safeguards approach for aerodynamic uranium enrichment plants. Because the process gas in an aerodynamic enrichment facility is a mixture of UF 6 and H 2 , a mass flow measurement in conjunction with a measurement of the uranium (or UF 6 ) concentration in the process gas is required to quantify the amount of uranium being fed into, and withdrawn from, the cascades for nuclear materials accountability verification. In-line enrichment monitors developed for the US gas centrifuge enrichment plant are found to be applicable only to pure UF 6 streams. Of the five gas flow meters evaluated, the orifice meter and the pitot tube meter are judged the best choices for the proposed applications: the first is recommended for low-velocity gas, small diameter piping; the latter, for high-velocity gas, large diameter piping. Of the six procedures evaluated for measurement of uranium or UF 6 concentration in a mixed process stream, infrared-ultraviolet-visible spectrophotometry is judged to be the best procedure currently available to perform the required measurement. 4 refs., 3 figs., 3 tabs

  6. Computer simulation of cooling properties of UF5 hot-clusters in argon

    International Nuclear Information System (INIS)

    Okamoto, Tsuyoshi; Ohno, Fubito

    1999-01-01

    Brownian collision-coalescence models have been proposed by many researchers to describe a cluster or a particle growth process. In these mathematical models, the effect of a cluster temperature on a sticking probability is not included, although the cluster temperature is one of the most important factors which determines the particle growth rate at the incipient stage of coagulation. A hot-cluster consisting of 30 UF 5 molecules is formed in a computer and is bombarded with argon atoms. Measuring a kinetic energy of argon atom scattered from the hot-cluster, the cluster temperature can be estimated by molecular dynamics simulations. It is concluded that the hot-cluster is rapidly cooled under the conditions of molecular laser isotope separation (MLIS) process, so that the cluster-argon system can reach its thermal equilibrium state. Therefore, in the analysis of the dynamics of clustering process, the temperature of UF 5 molecular cluster may be set equal to that of argon gas. (author)

  7. On-Line Enrichment Monitor for UF{sub 6} Gas Centrifuge Enrichment Plant

    Energy Technology Data Exchange (ETDEWEB)

    Ianakiev, K. D.; Boyer, B.; Favalli, A.; Goda, J. M.; Hill, T.; Keller, C.; Lombardi, M.; Paffett, M.; MacArthur, D. W.; McCluskey, C.; Moss, C. E.; Parker, R.; Smith, M. K.; Swinhoe, M. T. [Los Alamos National Laboratory, Los Alamos (United States)

    2012-06-15

    This paper is a continuation of the Advanced Enrichment Monitoring Technology for UF{sub 6} Gas Centrifuge Enrichment Plant (GCEP) work, presented in the 2010 IAEA Safeguards Symposium. Here we will present the system architecture for a planned side-by-side field trial test of passive (186-keV line spectroscopy and pressure-based correction for UF{sub 6} gas density) and active (186-keV line spectroscopy and transmission measurement based correction for UF{sub 6} gas density) enrichment monitoring systems in URENCO's enrichment plant in Capenhurst. Because the pressure and transmission measurements of UF{sub 6} are complementary, additional information on the importance of the presence of light gases and the UF{sub 6} gas temperature can be obtained by cross-correlation between simultaneous measurements of transmission, pressure and 186-keV intensity. We will discuss the calibration issues and performance in the context of accurate, on-line enrichment measurement. It is hoped that a simple and accurate on-line enrichment monitor can be built using the UF{sub 6} gas pressure provided by the Operator, based on online mass spectrometer calibration, assuming a negligible (a small fraction of percent) contribution of wall deposits. Unaccounted-for wall deposits present at the initial calibration will lead to unwanted sensitivity to changes in theUF{sub 6} gas pressure and thus to error in the enrichment results. Because the accumulated deposits in the cascade header pipe have been identified as an issue for Go/No Go measurements with the Cascade Header Enrichment Monitor (CHEM) and Continuous Enrichment Monitor (CEMO), it is important to explore their effect. Therefore we present the expected uncertainty on enrichment measurements obtained by propagating the errors introduced by deposits, gas density, etc. and will discuss the options for a deposit correction during initial calibration of an On-Line Enrichment Monitor (OLEM).

  8. Evaluation of a dry process for conversion of U-AVLIS product to UF6. Milestone U361

    International Nuclear Information System (INIS)

    1992-05-01

    A technical and engineering evaluation has been completed for a dry UF 6 production system to convert the product of an initial two-line U-AVLIS plant. The objective of the study has been to develop a better understanding of process design requirements, capital and operating costs, and demonstration requirements for this alternate process. This report summarizes the results of the study and presents various comparisons between the baseline and alternate processes, building on the information contained in UF 6 Product Alternatives Review Committee -- Final Report. It also provides additional information on flowsheet variations for the dry route which may warrant further consideration. The information developed by this study and conceptual design information for the baseline process will be combined with information to be developed by the U-AVLIS program and by industrial participants over the next twelve months to permit a further comparison of the baseline and alternate processes in terms of cost, risk, and compatibility with U-AVLIS deployment schedules and strategies. This comparative information will be used to make a final process flowsheet selection for the initial U-AVLIS plant by March 1993. The process studied is the alternate UF 6 production flowsheet. Process steps are (1) electron-beam distillation to reduce enriched product iron content from about 10 wt % or less, (2) hydrofluorination of the metal to UF 4 , (3) fluorination of UF 4 to UF 6 , (4) cold trap collection of the UF 6 product, (5) UF 6 purification by distillation, and (6) final blending and packaging of the purified UF 6 in cylinders. A preliminary system design has been prepared for the dry UF 6 production process based on currently available technical information. For some process steps, such information is quite limited. Comparisons have been made between this alternate process and the baseline plant process for UF 6 production

  9. On the critical temperature, normal boiling point, and vapor pressure of ionic liquids.

    Science.gov (United States)

    Rebelo, Luis P N; Canongia Lopes, José N; Esperança, José M S S; Filipe, Eduardo

    2005-04-07

    One-stage, reduced-pressure distillations at moderate temperature of 1-decyl- and 1-dodecyl-3-methylimidazolium bistriflilamide ([Ntf(2)](-)) ionic liquids (ILs) have been performed. These liquid-vapor equilibria can be understood in light of predictions for normal boiling points of ILs. The predictions are based on experimental surface tension and density data, which are used to estimate the critical points of several ILs and their corresponding normal boiling temperatures. In contrast to the situation found for relatively unstable ILs at high-temperature such as those containing [BF(4)](-) or [PF(6)](-) anions, [Ntf(2)](-)-based ILs constitute a promising class in which reliable, accurate vapor pressure measurements can in principle be performed. This property is paramount for assisting in the development and testing of accurate molecular models.

  10. Microwave measurements of water vapor partial pressure at high temperatures

    International Nuclear Information System (INIS)

    Latorre, V.R.

    1991-01-01

    One of the desired parameters in the Yucca Mountain Project is the capillary pressure of the rock comprising the repository. This parameter is related to the partial pressure of water vapor in the air when in equilibrium with the rock mass. Although there are a number of devices that will measure the relative humidity (directly related to the water vapor partial pressure), they generally will fail at temperatures on the order of 150C. Since thee author has observed borehole temperatures considerably in excess of this value in G-Tunnel at the Nevada Test Site (NTS), a different scheme is required to obtain the desired partial pressure data at higher temperatures. This chapter presents a microwave technique that has been developed to measure water vapor partial pressure in boreholes at temperatures up to 250C. The heart of the system is a microwave coaxial resonator whose resonant frequency is inversely proportional to the square root of the real part of the complex dielectric constant of the medium (air) filling the resonator. The real part of the dielectric constant of air is approximately equal to the square of the refractive index which, in turn, is proportional to the partial pressure of the water vapor in the air. Thus, a microwave resonant cavity can be used to measure changes in the relative humidity or partial pressure of water vapor in the air. Since this type of device is constructed of metal, it is able to withstand very high temperatures. The actual limitation is the temperature limit of the dielectric material in the cable connecting the resonator to its driving and monitoring equipment-an automatic network analyzer in our case. In the following sections, the theory of operation, design, construction, calibration and installation of the microwave diagnostics system is presented. The results and conclusions are also presented, along with suggestions for future work

  11. Study on the effect of subcooling on vapor film collapse on high temperature particle surface

    International Nuclear Information System (INIS)

    Abe, Yutaka; Tochio, Daisuke; Yanagida, Hiroshi

    2000-01-01

    Thermal detonation model is proposed to describe vapor explosion. According to this model, vapor film on pre-mixed high temperature droplet surface is needed to be collapsed for the trigger of the vapor explosion. It is pointed out that the vapor film collapse behavior is significantly affected by the subcooling of low temperature liquid. However, the effect of subcooling on micro-mechanism of vapor film collapse behavior is not experimentally well identified. The objective of the present research is to experimentally investigate the effect of subcooling on micro-mechanism of film boiling collapse behavior. As the results, it is experimentally clarified that the vapor film collapse behavior in low subcooling condition is qualitatively different from the vapor film collapse behavior in high subcooling condition. In case of vapor film collapse by pressure pulse, homogeneous vapor generation occurred all over the surface of steel particle in low subcooling condition. On the other hand, heterogeneous vapor generation was observed for higher subcooling condition. In case of vapor film collapse spontaneously, fluctuation of the gas-liquid interface after quenching propagated from bottom to top of the steel particle heterogeneously in low subcooling condition. On the other hand, simultaneous vapor generation occurred for higher subcooling condition. And the time transient of pressure, particle surface temperature, water temperature and visual information were simultaneously measured in the vapor film collapse experiment by external pressure pulse. Film thickness was estimated by visual data processing technique with the pictures taken by the high-speed video camera. Temperature and heat flux at the vapor-liquid interface were estimated by solving the heat condition equation with the measured pressure, liquid temperature and vapor film thickness as boundary conditions. Movement of the vapor-liquid interface were estimated with the PIV technique with the visual observation

  12. Vapor-liquid equilibrium thermodynamics of N2 + CH4 - Model and Titan applications

    Science.gov (United States)

    Thompson, W. R.; Zollweg, John A.; Gabis, David H.

    1992-01-01

    A thermodynamic model is presented for vapor-liquid equilibrium in the N2 + CH4 system, which is implicated in calculations of the Titan tropospheric clouds' vapor-liquid equilibrium thermodynamics. This model imposes constraints on the consistency of experimental equilibrium data, and embodies temperature effects by encompassing enthalpy data; it readily calculates the saturation criteria, condensate composition, and latent heat for a given pressure-temperature profile of the Titan atmosphere. The N2 content of condensate is about half of that computed from Raoult's law, and about 30 percent greater than that computed from Henry's law.

  13. Temperature dependences of saturated vapor pressure and the enthalpy of vaporization of n-pentyl esters of dicarboxylic acids

    Science.gov (United States)

    Portnova, S. V.; Krasnykh, E. L.; Levanova, S. V.

    2016-05-01

    The saturated vapor pressures and enthalpies of vaporization of n-pentyl esters of linear C2-C6 dicarboxylic acids are determined by the transpiration method in the temperature range of 309.2-361.2 K. The dependences of enthalpies of vaporization on the number of carbon atoms in the molecule and on the retention indices have been determined. The predictive capabilities of the existing calculation schemes for estimation of enthalpy of vaporization of the studied compounds have been analyzed.

  14. Combined ground- and satellite-based profiling of temperature and water vapor

    International Nuclear Information System (INIS)

    Stankov, B.B.; Westwater, E.R.; Snider, J.B.; Churnside, J.H.

    1994-01-01

    The fusion or integration of meteorological and radiative data from a range of instrumentation into a representative picture of temperature, water vapor, and clouds over a CART domain will be a challenging task for four-dimensional data assimilation models. In the work reported here, we have summarized work supported by DOE's algorithm development program including combined RASS and TIROS Operational Vertical Sounder (TOVS) temperature sensing, water vapor profiles from dual-channel radiometers, and neural network radiometric temperature retrievals

  15. In-reactor oxidation of zircaloy-4 under low water vapor pressures

    Science.gov (United States)

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

    2015-01-01

    Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 °C). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr-4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

  16. In-reactor oxidation of zircaloy-4 under low water vapor pressures

    International Nuclear Information System (INIS)

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

    2015-01-01

    Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 ℃). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr- 4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

  17. Scenarios and analytical methods for UF6 releases at NRC-licensed fuel cycle facilities

    International Nuclear Information System (INIS)

    Siman-Tov, M.; Dykstra, J.; Holt, D.D.; Huxtable, W.P.; Just, R.A.; Williams, W.R.

    1984-06-01

    This report identifies and discusses potential scenarios for the accidental release of UF 6 at NRC-licensed UF 6 production and fuel fabrication facilities based on a literature review, site visits, and DOE enrichment plant experience. Analytical tools needed for evaluating source terms for such releases are discussed, and the applicability of existing methods is reviewed. Accident scenarios are discussed under the broad headings of cylinder failures, UF 6 process system failures, nuclear criticality events, and operator errors and are categorized by location, release source, phase of UF 6 prior to release, release flow characteristics, release causes, initiating events, and UF 6 inventory at risk. At least three types of releases are identified for further examination: (1) a release from a liquid-filled cylinder outdoors, (2) a release from a pigtail or cylinder in a steam chest, (3) an indoor release from either (a) a pigtail or liquid-filled cylinder or (b) other indoor source depending on facility design and operating procedures. Indoor release phenomena may be analyzed to determine input terms for a ventilation model by using a time-dependent homogeneous compartment model or a more complex hydrodynamic model if time-dependent, spatial variations in concentrations, temperature, and pressure are important. Analytical tools for modeling directed jets and explosive releases are discussed as well as some of the complex phenomena to be considered in analyzing UF 6 releases both indoors and outdoors

  18. Validation of MIPAS IMK/IAA temperature, water vapor, and ozone profiles with MOHAVE-2009 campaign measurements

    Directory of Open Access Journals (Sweden)

    G. P. Stiller

    2012-02-01

    Full Text Available MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT, Institute for Meteorology and Climate Research (IMK and CSIC, Instituto de Astrofísica de Andalucía (IAA and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infra-red (FTIR spectrometers. For MIPAS temperatures (version V4O_T_204, no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203 is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause, but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202 has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution

  19. Validation of MIPAS IMK-IAA Temperature, Water Vapor, and Ozone Profiles with MOHAVE-2009 Campaign Measurements

    Science.gov (United States)

    Stiller, Gabrielle; Kiefer, M.; Eckert, E.; von Clarmann, T.; Kellmann, S.; Garcia-Comas, M.; Funke, B.; Leblanc, T.; Fetzer, E.; Froidevaux, L.; hide

    2012-01-01

    MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK) and CSIC, Instituto de Astrofisica de Andalucia (IAA) and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infrared (FTIR) spectrometers. For MIPAS temperatures (version V4O_T_204), no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203) is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause), but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202) has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution. No further

  20. Conformal coverage of poly(3,4-ethylenedioxythiophene) films with tunable nanoporosity via oxidative chemical vapor deposition

    NARCIS (Netherlands)

    Im, S.G.; Kusters, D.J.N.; Choi, W.; Baxamusa, S.H.; Sanden, van de M.C.M.; Gleason, K.K.

    2008-01-01

    Novel nanoporous poly(3,4-ethylenedioxythiophene) (PEDOT) films with basalt-like surface morphology are successfully obtained via a one-step, vapor phase process of oxidative chemical vapor deposition (oCVD) by introducing a new oxidant, CuCl2, The substrate temperature of the oCVD process is a

  1. UF{sub 6} cylinder fire test

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.H. [Oak Ridge K-25 Site, Oak Ridge, TN (United States)

    1991-12-31

    With the increasing number of nuclear reactors for power generation, there is a comparable increase in the amount of UF{sub 6} being transported. Likewise, the probability of having an accident involving UF{sub 6}-filled cylinders also increases. Accident scenarios which have been difficult to assess are those involving a filled UF{sub 6} cylinder subjected to fire. A study is underway at the Oak Ridge K-25 Site, as part of the US DOE Enrichment Program, to provide empirical data and a computer model that can be used to evaluate various cylinder-in-fire scenarios. It is expected that the results will provide information leading to better handling of possible fire accidents as well as show whether changes should be made to provide different physical protection during shipment. The computer model being developed will be capable of predicting the rupture of various cylinder sizes and designs as well as the amount of UF{sub 6}, its distribution in the cylinder, and the conditions of the fire.

  2. Low temperature measurement of the vapor pressures of planetary molecules

    Science.gov (United States)

    Kraus, George F.

    1989-01-01

    Interpretation of planetary observations and proper modeling of planetary atmospheres are critically upon accurate laboratory data for the chemical and physical properties of the constitutes of the atmospheres. It is important that these data are taken over the appropriate range of parameters such as temperature, pressure, and composition. Availability of accurate, laboratory data for vapor pressures and equilibrium constants of condensed species at low temperatures is essential for photochemical and cloud models of the atmospheres of the outer planets. In the absence of such data, modelers have no choice but to assume values based on an educated guess. In those cases where higher temperature data are available, a standard procedure is to extrapolate these points to the lower temperatures using the Clausius-Clapeyron equation. Last summer the vapor pressures of acetylene (C2H2) hydrogen cyanide (HCN), and cyanoacetylene (HC3N) was measured using two different methods. At the higher temperatures 1 torr and 10 torr capacitance manometers were used. To measure very low pressures, a technique was used which is based on the infrared absorption of thin film (TFIR). This summer the vapor pressure of acetylene was measured the TFIR method. The vapor pressure of hydrogen sulfide (H2S) was measured using capacitance manometers. Results for H2O agree with literature data over the common range of temperature. At the lower temperatures the data lie slightly below the values predicted by extrapolation of the Clausius-Clapeyron equation. Thin film infrared (TFIR) data for acetylene lie significantly below the values predicted by extrapolation. It is hoped to bridge the gap between the low end of the CM data and the upper end of the TFIR data in the future using a new spinning rotor gauge.

  3. Low temperature synthesis of Zn nanowires by physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Philipp; Kast, Michael; Brueckl, Hubert [Austrian Research Centers GmbH ARC, Nano- Systemtechnologies, Donau-City-Strasse 1, A-1220 Wien (Austria)

    2007-07-01

    We demonstrate catalytic growth of zinc nanowires by physical vapor deposition at modest temperatures of 125-175 C on various substrates. In contrast to conventional approaches using tube furnaces our home-built growth system allows to control the vapor sources and the substrate temperature separately. The silicon substrates were sputter coated with a thin gold layer as metal catalyst. The samples were heated to the growth temperature and subsequently exposed to the zinc vapor at high vacuum conditions. The work pressure was adjusted by the partial pressure of oxygen or argon flow gas. Scanning electron microscopy and atomic force microscopy characterizations revealed that the nanowires exhibit straight, uniform morphology and have diameters in the range of 50-350 nm and lengths up to 70 {mu}m. The Zn nanowires grow independently of the substrates crystal orientation via a catalytic vapor-solid growth mechanism. Since no nanowire formation was observed without gold coating, we expect that the onedimensional growth is initiated by a surface reactive Au seed. ZnO nanowires can be produced in the same preparation chamber by oxidation at 500 C in 1atm (80% Ar, 20% O{sub 2}) for 1 hour. ZnO is highly attractive for sensor applications.

  4. UO{sub 2} surface oxidation by mixtures of water vapor and hydrogen as a function of temperature

    Energy Technology Data Exchange (ETDEWEB)

    Espriu-Gascon, A., E-mail: alexandra.espriu@upc.edu [Department of Chemical Engineering, Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Llorca, J.; Domínguez, M. [Institut de Tècniques Energètiques (INTE), Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE), Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Giménez, J.; Casas, I. [Department of Chemical Engineering, Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Pablo, J. de [Department of Chemical Engineering, Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Fundació CTM Centre Tecnològic, Plaça de la Ciència 2, E-08243 Manresa (Spain)

    2015-12-15

    In the present work, X-Ray Photoelectron Spectroscopy (XPS) was used to study the effect of water vapor on the UO{sub 2} surface as a function of temperature. The experiments were performed in situ inside a high pressure chamber attached to the XPS instrument. UO{sub 2} samples were put in contact with either hydrogen or argon streams, saturated with water at room temperature, and the sample surface evolution was analyzed by XPS. In the case of the water vapor/argon experiments, one experiment at 350 °C was performed and, in the case of the water vapor/hydrogen experiments, the temperatures used inside the reactor were 60, 120, 200 and 350 °C. On one hand, in presence of argon, the results obtained showed that the water vapor in the argon stream oxidized 93% of the U(IV) in the sample surface. On the other hand, the degree of UO{sub 2} surface oxidation showed a different dependence on the temperature in the experiments performed in the presence of hydrogen: the maximum surface oxidation occurred at 120 °C, where 65.4% of U(IV) in the sample surface was oxidized, while at higher temperatures, the surface oxidation decreased. This observation is attributed to the increase of hydrogen reducing effect when temperature increases which prevents part of the oxidation of the UO{sub 2} surface by the water vapor. - Highlights: • UO{sub 2} surface has been oxidized by water vapor in an argon stream at 350 °C. • H{sub 2} reduced more uranium oxidation produced by water at 350 °C when compared to Ar. • In H{sub 2} presence, the uranium oxidation produced by water depends on the temperature.

  5. Evaluation of a dry process for conversion of U-AVLIS product to UF{sub 6}. Milestone U361

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-05-01

    A technical and engineering evaluation has been completed for a dry UF{sub 6} production system to convert the product of an initial two-line U-AVLIS plant. The objective of the study has been to develop a better understanding of process design requirements, capital and operating costs, and demonstration requirements for this alternate process. This report summarizes the results of the study and presents various comparisons between the baseline and alternate processes, building on the information contained in UF{sub 6} Product Alternatives Review Committee -- Final Report. It also provides additional information on flowsheet variations for the dry route which may warrant further consideration. The information developed by this study and conceptual design information for the baseline process will be combined with information to be developed by the U-AVLIS program and by industrial participants over the next twelve months to permit a further comparison of the baseline and alternate processes in terms of cost, risk, and compatibility with U-AVLIS deployment schedules and strategies. This comparative information will be used to make a final process flowsheet selection for the initial U-AVLIS plant by March 1993. The process studied is the alternate UF{sub 6} production flowsheet. Process steps are (1) electron-beam distillation to reduce enriched product iron content from about 10 wt % or less, (2) hydrofluorination of the metal to UF{sub 4}, (3) fluorination of UF{sub 4} to UF{sub 6}, (4) cold trap collection of the UF{sub 6} product, (5) UF{sub 6} purification by distillation, and (6) final blending and packaging of the purified UF{sub 6} in cylinders. A preliminary system design has been prepared for the dry UF{sub 6} production process based on currently available technical information. For some process steps, such information is quite limited. Comparisons have been made between this alternate process and the baseline plant process for UF{sub 6} production.

  6. Heat transfer characteristics of UF6 in a container heated from outer surface. Pt. 1. Thermal hydraulic analysis method taking account of phase change and volume expansion

    International Nuclear Information System (INIS)

    Wataru, Masumi; Gomi, Yoshio; Yamakawa, Hidetsugu; Tsumune, Daisuke

    1995-01-01

    Natural UF6 is transported in a steel container from foreign countries to the enrichment plant in Japan. If the container meets fire accident, it is heated by fire (800degC) and rupture of the container may occur. For the safety point of view, it is necessary to know whether rupture occurs or not. Because UF6 has a radiological and chemical hazards, it is difficult to perform a demonstration test with UF6. So thermal calculation method has to be developed. The rupture is caused by UF6 gaseous pressure or volume expansion of liquid UF6. To know time history of internal pressure and temperature distribution in the container, it is important to evaluate thermal phenomena of UF6. When UF6 is heated, it changes from solid to liquid or gas at low temperature (64degC) and then its volume expands little by little. In this study, thermal calculation method has been developed taking phase change and thermal expansion of UF6 into account. In the calculation, a two-dimensional model is adopted and natural convection of liquid UF6 is analyzed. As a result of this study, numerical solutions have been obtained taking phase change and volume expansion into account. (author)

  7. Criticality safety review of 2 1/2-, 10-, and 14-ton UF6 cylinders

    International Nuclear Information System (INIS)

    Broadhead, B.L.

    1991-10-01

    Currently, UF 6 cylinders designed to contain 2 1/2 tons of UF 6 are classified as Fissile Class 2 packages with a transport index (TI) of 5 for the purpose of transportation. The 10-ton UF 6 cylinders are classified as Fissile Class 1 with no TI assigned for transportation. The 14-ton cylinders, although not certified for transport with enrichments greater than 1 wt % because they have no approved overpack, can be used in on-site operations for enrichments greater than 1 wt %. The maximum 235 U enrichments for these cylinders are 5.0 wt % for the 2 1/2-ton cylinder and 4.5 wt % for the 10- and 14-ton cylinders. This work reviews the suitability for reclassification of the 2 1/2-ton UF 6 packages as Fissile Class 1 with a maximum 235 U enrichment of 5 wt %. Additionally, the 10- and 14-ton cylinders are reviewed to address a change in maximum 235 U enrichment from 4.5 to 5 wt %. Based on this evaluation, the 2 1/2-ton UF 6 cylinders meet the 10 CFR.71 criteria for Fissile Class 1 packages, and no TI is needed for criticality safety purposes; however, a TI may be required based on radiation from the packages. Similarly, the 10- and 14-ton UF 6 packages appear acceptable for a maximum enrichment rating change to 5 wt % 235 U. 11 refs., 13 figs., 7 tabs

  8. Thermodynamic functions and vapor pressures of uranium and plutonium oxides at high temperatures

    International Nuclear Information System (INIS)

    Green, D.W.; Reedy, G.T.; Leibowitz, L.

    1977-01-01

    The total energy release in a hypothetical reactor accident is sensitive to the total vapor pressure of the fuel. Thermodynamic functions which are accurate at high temperature can be calculated with the methods of statistical mechanics provided that needed spectroscopic data are available. This method of obtaining high-temperature vapor pressures should be greatly superior to the extrapolation of experimental vapor pressure measurements beyond the temperature range studied. Spectroscopic data needed for these calculations are obtained from infrared spectroscopy of matrix-isolated uranium and plutonium oxides. These data allow the assignments of the observed spectra to specific molecular species as well as the calculation of anharmonicities for monoxides, bond angles for dioxides, and molecular geometries for trioxides. These data are then employed, in combination with data on rotational and electronic molecular energy levels, to determine thermodynamic functions that are suitable for the calculation of high-temperature vapor pressures

  9. Dispersion of UO2F2 aerosol and HF vapor in the operating floor during winter ventilation at the Paducah Gaseous Diffusion Plant

    International Nuclear Information System (INIS)

    Kim, S.H.; Chen, N.C.J.; Taleyarkhan, R.P.; Keith, K.D.; Schmidt, R.W.; Carter, J.C.

    1996-01-01

    The gaseous diffusion process is currently employed at two plants in the US: the Paducah Gaseous Diffusion Plant and the Portsmouth Gaseous Diffusion Plant. As part of a facility-wide safety evaluation, a postulated design basis accident involving large line-rupture induced releases of uranium hexafluoride (UF 6 ) into the process building of a gaseous diffusion plant (GDP) is evaluated. When UF 6 is released into the atmosphere, it undergoes an exothermic chemical reaction with moisture (H 2 O) in the air to form vaporized hydrogen fluoride (HF) and aerosolized uranyl fluoride (UO 2 F 2 ). These reactants disperse in the process building and transport through the building ventilation system. The ventilation system draws outside air into the process building, distributes it evenly throughout the building, and discharges it to the atmosphere at an elevated temperature. Since air is recirculated from the cell floor area to the operating floor, issues concerning in-building worker safety and evacuation need to be addressed. Therefore, the objective of this study is to evaluate the transport of HF vapor and UO 2 F 2 aerosols throughout the operating floor area following B-line break accident in the cell floor area

  10. Growth of NH4Cl Single Crystal from Vapor Phase in Vertical Furnace

    Science.gov (United States)

    Nigara, Yutaka; Yoshizawa, Masahito; Fujimura, Tadao

    1983-02-01

    A pure and internally stress-free single crystal of NH4Cl was grown successfully from the vapor phase. The crystal measured 1.6 cmφ× 2 cm and had the disordered CsCl structure, which was stable below 184°C. The crystal was grown in an ampoule in a vertical furnace, in which the vapor was efficiently transported both by diffusion and convection. In line with the growth mechanism of a single crystal, the temperature fluctuation (°C/min) on the growth interface was kept smaller than the product of the temperature gradient (°C/cm) and the growth rate (cm/min). The specific heat of the crystal was measured around -31°C (242 K) during cooling and heating cycles by AC calorimetry. The thermal hysteresis (0.4 K) obtained here was smaller than that (0.89 K) of an NH4Cl crystal grown from its aqueous solution with urea added as a habit modifier.

  11. Materials considerations for UF6 gas-core reactor. Interim report for preliminary design study

    International Nuclear Information System (INIS)

    Wagner, P.

    1977-04-01

    The limiting materials problem in a high-temperature UF 6 core reactor is the corrosion of the core containment vessel. The UF 6 , the lower fluorides of uranium, and the fluorine that exist at the anticipated reactor operating conditions (1000 K and about one atmosphere UF 6 ) are all corrosive. Because of this, the materials evaluation effort for this reactor design study has concentrated on the identification of a viable system for the containment vessel that meets both the materials and neutronic requirements. A study of the literature has revealed that the most promising corrosion-resistant candidates are Ni or Ni-Al alloys. One of the conclusions of this work is that the containment vessel use a nickel liner or clad since the use of Ni as a structural member is precluded by its relative blackness to thermal neutrons. Estimates of corrosion rates of Ni and Ni-Al alloys, the effects of the pressure and temperature of F 2 on the corrosion rates, calculated equilibrium gas compositions at reactor core operating conditions, suggested methods of fabrication, and recommendations for future research and development are included

  12. Computational fluid dynamics tracking of UF6 reaction products release into a gaseous diffusion plant cell housing

    International Nuclear Information System (INIS)

    Wendel, M.W.; Chen, N.C.J.; Kim, S.H.; Taleyarkhan, R.P.; Keith, K.D.; Schmidt, R.W.

    1996-01-01

    A three-dimensional (3-D) computational fluid dynamics (CFD) model has been developed using CFDS-FLOW3D Version 3.3 to model the transport of aerosol products formed during a release of uranium hexafluoride (UF 6 ) into a gaseous diffusion plant (GDP) process building. As part of a facility-wide safety evaluation, a one-dimensional (1-D) analysis of aerosol/vapor transport following such an hypothesized severe accident is being performed. The objective of this study is to supplement the 1-D analysis with more detailed 3-D results. Specifically, the goal is to quantify the distribution of aerosol passing out of the process building during the hypothetical accident. This work demonstrates a useful role for CFD in large 3-D problems, where some experimental data are available for calibrating key parameters and the desired results are global (total time-integrated aerosol flow rates across a few boundary surfaces) as opposed to local velocities, temperatures, or heat transfer coefficients

  13. Organic vapor discrimination with chemiresistor arrays of temperature modulated tin-oxide nanowires and thiolate-monolayer-protected gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Scholten, K; Bohrer, F I; Dattoli, E; Lu, W; Zellers, E T, E-mail: ezellers@umich.edu [Center for Wireless Integrated Microsystems, University of Michigan, Ann Arbor, MI 48109-2122 (United States)

    2011-03-25

    This paper explores the discrimination of organic vapors with arrays of chemiresistors (CRs) employing interface layers of tin-oxide nanowires (NWs) and thiolate-monolayer-protected gold nanoparticles (MPNs). The former devices use contact-printed mats of NWs on micro-hotplate membranes to bridge a pair of metal electrodes. Oxidation at the NW surface causes changes in charge transport, the temperature dependence of which differs among different vapors, permitting vapor discrimination. The latter devices use solvent cast films of MPNs on interdigital electrodes operated at room temperature. Sorption into the organic monolayers causes changes in film tunneling resistance that differ among different vapors and MPN structures, permitting vapor discrimination. Here, we compare the performance and assess the 'complementarity' of these two types of sensors. Calibrated responses from an NW CR operated at two different temperatures and from a set of four different MPN CRs were generated for three test vapors: n-hexane, toluene, and nitromethane. This pooled data set was then analyzed using principal components regression classification models with varying degrees of random error superimposed on the responses via Monte Carlo simulation in order to estimate the rates of recognition/discrimination for arrays comprising different combinations of sensors. Results indicate that the diversity of most of the dual MPN-CR arrays exceeds that of the dual NW-CR array. Additionally, in assessing all possible arrays of 4-6 CR sensors, the recognition rates of the hybrid arrays (i.e. MPN + NW) were no better than that of the 4-sensor array containing only MPN CRs.

  14. Vapor pressures and vaporization enthalpy of (−) α-bisabolol and (dl) menthol by correlation gas chromatography

    International Nuclear Information System (INIS)

    Keating, Leasa; Harris, Harold H.; Chickos, James S.

    2017-01-01

    Highlights: • The vaporization enthalpy and vapor pressure of (−) α-bisabolol and (dl)-menthol have been measured as a function of temperature. • Vapor pressures, vaporization enthalpies and boiling temperatures have been compared to available literature data. • Vapor pressures of (l)-menthol are compared to (dl)-menthol. - Abstract: The vapor pressures and vaporization enthalpies of (−) α-bisabolol and (dl)-menthol, two GRAS chemicals (generally recognized as safe) are evaluated by correlation gas chromatography using a series of saturated primary alcohols as standards. Vaporization enthalpies of (96.6 ± 2.4) and (74.2 ± 2.8) kJ mol −1 and vapor pressures of p/Pa = (0.020 ± 0.003) and (4.5 ± 0.44) were evaluated at T = 298.15 K for (−) α-bisabolol and (dl)-menthol, respectively, and compared to literature values. The vapor pressures of both compounds from T = (298.15 to 500) K have been derived from correlations using vapor pressures of a series of 1-alkanols and corresponding gas chromatographic retention times at 10 K intervals. The results were fit to a second order polynomial. Calculated normal boiling temperatures of T B = (574.8 and 492.7) K are calculated for (−) α-bisabolol and (dl)-menthol, respectively. A normal boiling temperature of T B = (485.2, and 489.7) K has previously been reported for (dl)-menthol. Vapor pressures for both (l)-menthol and (dl)-menthol from a previous study and (dl)-menthol from this study are compared with literature values.

  15. Thermodynamic data for uranium fluorides

    International Nuclear Information System (INIS)

    Leitnaker, J.M.

    1983-03-01

    Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF 4 and UF 6 , including UF 4 (solid and gas), U 4 F 17 (solid), U 2 F 9 (solid), UF 5 (solid and gas), U 2 F 10 (gas), and UF 6 (solid, liquid, and gas). Included are thermal function - the heat capacity, enthalpy, and free energy function, heats of formation, and vaporization behavior

  16. Long-term evaluation of fluoroelastomer O-rings in UF6

    International Nuclear Information System (INIS)

    Russell, R.G.; Otey, M.G.; Dippo, G.L.

    1986-01-01

    A major component in the gaseous centrifuge enrichment plant (GCEP) was fluoroelastomer O-rings, which were used to seal the uranium hexafluoride (UF 6 ) gas system. A program utilizing accelerated test conditions was used to help identify the best material out of four selected candidates and to predict the service life of these materials at GCEP conditions. The tests included accelerated temperatures, mechanical stress, and UF 6 exposure. Data were evaluated using the Newman--Keuls 1 ranking system to identify the best material and a zero-order reaction rate equation to help predict service life. This presentation includes a description of the test facility, the materials tested, the types of tests, objectives of the study, service life predictions, and conclusions. The O-rings are predicted to last approx. 30 years, and a high-molecular-weight polymer had the best performance ranking

  17. THERMOPHYSICAL PROPERTIES AND WATER ACTIVITY OF TRANSFERRED CHEESE (UF

    Directory of Open Access Journals (Sweden)

    Mohsen Dalvi Esfahan

    2015-06-01

    Full Text Available Few data are available on the thermophysical properties of cheese in the ripening process.The main objective of this work was to investigate the effects of brining and temperature on the thermophysical properties, i.e., thermal conductivity, specific heat, density and water activity of UF cheese and finally we measure surface heat transfer coefficient .Then we develop models for thermophysical properties based on physical and multiple regression concept .

  18. Temperature varying photoconductivity of GeSn alloys grown by chemical vapor deposition with Sn concentrations from 4% to 11%

    Energy Technology Data Exchange (ETDEWEB)

    Hart, John; Hazbun, Ramsey; Gupta, Jay; Kolodzey, James [Department of Electrical Engineering, University of Delaware, 140 Evans Hall, Newark, Delaware 19716 (United States); Adam, Thomas [College of Nanoscale Science and Engineering, SUNY, Albany, New York 12203 (United States); Kim, Yihwan; Huang, Yi-Chiau [Applied Materials, Sunnyvale, California 94085 (United States); Reznicek, Alexander [IBM Research at Albany Nanotech, Albany, New York 12203 (United States)

    2016-03-07

    Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl{sub 4} precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.

  19. Temperature varying photoconductivity of GeSn alloys grown by chemical vapor deposition with Sn concentrations from 4% to 11%

    International Nuclear Information System (INIS)

    Hart, John; Hazbun, Ramsey; Gupta, Jay; Kolodzey, James; Adam, Thomas; Kim, Yihwan; Huang, Yi-Chiau; Reznicek, Alexander

    2016-01-01

    Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl 4 precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.

  20. Temperature varying photoconductivity of GeSn alloys grown by chemical vapor deposition with Sn concentrations from 4% to 11%

    Science.gov (United States)

    Hart, John; Adam, Thomas; Kim, Yihwan; Huang, Yi-Chiau; Reznicek, Alexander; Hazbun, Ramsey; Gupta, Jay; Kolodzey, James

    2016-03-01

    Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl4 precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.

  1. Method and apparatus for measuring enrichment of UF6

    Science.gov (United States)

    Hill, Thomas Roy [Santa Fe, NM; Ianakiev, Kiril Dimitrov [Los Alamos, NM

    2011-06-07

    A system and method are disclosed for determining the enrichment of .sup.235U in Uranium Hexafluoride (UF6) utilizing synthesized X-rays which are directed at a container test zone containing a sample of UF6. A detector placed behind the container test zone then detects and counts the X-rays which pass through the container and the UF6. In order to determine the portion of the attenuation due to the UF6 gas alone, this count rate may then be compared to a calibration count rate of X-rays passing through a calibration test zone which contains a vacuum, the test zone having experienced substantially similar environmental conditions as the actual test zone. Alternatively, X-rays of two differing energy levels may be alternately directed at the container, where either the container or the UF6 has a high sensitivity to the difference in the energy levels, and the other having a low sensitivity.

  2. Water vapor pressure over molten KH_2PO_4 and demonstration of water electrolysis at ∼300 °C

    International Nuclear Information System (INIS)

    Berg, R.W.; Nikiforov, A.V.; Petrushina, I.M.; Bjerrum, N.J.

    2016-01-01

    Highlights: • The vapor pressure over molten KH_2PO_4 was measured by Raman spectroscopy to be about 8 bars at ∼300 °C. • Raman spectroscopy shows that molten KH_2PO_4 under its own vapor pressure contains much dissolved water. • It is demonstrated spectroscopically that water electrolysis is possible in KH_2PO_4 electrolyte forming H_2 and O_2 at 300 °C. • Molten KH_2PO_4 is a possible electrolyte for water electrolysis. - Abstract: A new potentially high-efficiency electrolyte for water electrolysis: molten monobasic potassium phosphate, KH_2PO_4 or KDP has been investigated at temperatures ∼275–325 °C. At these temperatures, KH_2PO_4 was found to dissociate into H_2O gas in equilibrium with a melt mixture of KH_2PO_4−K_2H_2P_2O_7−KPO_3−H_2O. The water vapor pressure above the melt, when contained in a closed ampoule, was determined quantitatively vs. temperature by use of Raman spectroscopy with methane or hydrogen gas as an internal calibration standard, using newly established relative ratios of Raman scattering cross sections of water and methane or hydrogen to be 0.40 ± 0.02 or 1.2 ± 0.03. At equilibrium the vapor pressure was much lower than the vapor pressure above liquid water at the same temperature. Electrolysis was realized by passing current through closed ampoules (vacuum sealed quartz glass electrolysis cells with platinum electrodes and the electrolyte melt). The formation of mixtures of hydrogen and oxygen gases as well as the water vapor was detected by Raman spectroscopy. In this way it was demonstrated that water is present in the new electrolyte: molten KH_2PO_4 can be split by electrolysis via the reaction 2H_2O → 2H_2 + O_2 at temperatures ∼275–325 °C. At these temperatures, before the start of the electrolysis, the KH_2PO_4 melt gives off H_2O gas that pressurizes the cell according to the following dissociations: 2KH_2PO_4 ↔ K_2H_2P_2O_7 + H_2O ↔ 2KPO_3 + 2H_2O. The spectra show however that the water by

  3. Water vapor pressure over molten KH2PO4 and demonstration of water electrolysis at ∼300ºC

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Nikiforov, Aleksey Valerievich; Petrushina, Irina

    2016-01-01

    A new potentially high-efficiency electrolyte for water electrolysis: molten monobasic potassium phosphate, KH2PO4 or KDP has been investigated at temperatures ∼275–325 °C. At these temperatures, KH2PO4 was found to dissociate into H2O gas in equilibrium with a melt mixture of KH2PO4—K2H2P2O7—KPO3...... of water and methane or hydrogen to be 0.40 ± 0.02 or 1.2 ± 0.03. At equilibrium the vapor pressure was much lower than the vapor pressure above liquid water at the same temperature. Electrolysis was realized by passing current through closed ampoules (vacuum sealed quartz glass electrolysis cells...... with platinum electrodes and the electrolyte melt). The formation of mixtures of hydrogen and oxygen gases as well as the water vapor was detected by Raman spectroscopy. In this way it was demonstrated that water is present in the new electrolyte: molten KH2PO4 can be split by electrolysis via the reaction 2H2O...

  4. HEU to LEU Conversion and Blending Facility: UF6 blending alternative to produce LEU UF6 for commercial use

    International Nuclear Information System (INIS)

    1995-09-01

    US DOE is examining options for disposing of surplus weapons-usable fissile materials and storage of all weapons-usable fissile materials; the nuclear material will be converted to a form more proliferation- resistant than the original form. Examining options for increasing the proliferation resistance of highly enriched uranium (HEU) is part of this effort. Five technologies for blending HEU will be assessed; blending as UF 6 to produce a UF 6 product for commercial use is one of them. This document provides data to be used in the environmental impact analysis for the UF 6 blending HEU disposition option. Resource needs, employment needs, waste and emissions from plant, hazards, accident scenarios, and intersite transportation are discussed

  5. Review of potential models for UF6 dispersion

    International Nuclear Information System (INIS)

    Sykes, R.I.; Lewellen, W.S.

    1992-07-01

    A survey of existing atmospheric dispersion models has been conducted to determine the most appropriate basis for the development of a model for predicting the consequences of an accidental UF 6 release. The model is required for safety analysis studies and should therefore be computationally efficient. The release of UF 6 involves a number of physical phenomena which make the situation more complicated than passive dispersion of a trace gas. The safety analysis must consider the density variations in the UF 6 cloud, which can be heavier or lighter than the ambient air. The release also involves rapid chemical reactions and associated heat release, which must be modeled. Other Department of Energy storage facilities require a dense gas prediction capability, so the model must be sufficiently general for use with a variety of release scenarios. The special problems associated with UF 6 make it unique, so there are very few models with existing capability for the problem. There are, however, a large number of dense gas dispersion models, some with relevant chemical reaction modeling, that could potentially form the basis of an advanced UF 6 model. We have examined a large selection of possible candidates, and selected 5 models for detailed consideration

  6. Vapor-Liquid Equilibrium in the Mixture 1,1-Difluoroethane C2H4F2 + C4H8 2-Methylpropene (EVLM1131, LB5730_E)

    Science.gov (United States)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture 1,1-Difluoroethane C2H4F2 + C4H8 2-Methylpropene (EVLM1131, LB5730_E)' providing data from direct measurement of pressure and mole fraction in vapor phase at variable mole fraction in liquid phase and constant temperature.

  7. Vapor pressures and enthalpies of vaporization of a series of γ and δ-lactones by correlation gas chromatography

    International Nuclear Information System (INIS)

    Kozlovskiy, Mikhail; Gobble, Chase; Chickos, James

    2014-01-01

    Highlights: • The vaporization enthalpies of γ-octanolactone, γ- and δ-undecanolactone and γ and δ-dodecanolactone are reported. • Equations for predicting the vapor pressures over the temperature range T = (298.15 to 350) K are provided. • Vaporization enthalpies are compared to predicted values. - Abstract: The vaporization enthalpies of γ-octanolactone, γ- and δ-undecanolactone and γ and δ-dodecanolactone used commercially as flavor ingredients are reported as are their vapor pressures over the temperature range T = (298.15 to 350) K. Vaporization enthalpies at T = 298.15 K of: (66.0 ± 3.9), (79.4 ± 4.4), (80.1 ± 4.5), (83.9 ± 4.6), and (84.61 ± 4.7) kJ · mol −1 and vapor pressures also at T = 298.15 K of: (2.8 ± 0.9), (0.12 ± 0.05), (0.09 ± 0.04), (0.04 ± 0.02), and (0.03 ± 0.02) Pa, respectively, have been evaluated by correlation gas chromatography experiments. The vaporization enthalpies of the lactones studied are reproduced within ±0.5 kJ · mol −1 using a group additivity scheme reported previously for γ- and δ-lactones. The vaporization enthalpies of the γ- and δ-lactones are compared to a similar series of ω-lactones

  8. Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium-plutonium dioxide at high temperatures

    International Nuclear Information System (INIS)

    Green, D.W.; Fink, J.K.; Leibowitz, L.

    1982-01-01

    Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric uranium-plutonium dioxide condensed phase (U/sub 1-y/Pu/sub y/)O/sub 2-x/, as functions of T, x, and y, have been calculated for 0.0 less than or equal to x less than or equal to 0.1, 0.0 less than or equal to y less than or equal to 0.3, and for the temperature range 2500 less than or equal to T less than or equal to 6000 K. The range of compositions and temperatures was limited to the region of interest to reactor safety analysis. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen potential model to obtain partial pressures of O, O 2 , Pu, PuO, PuO 2 , U, UO, UO 2 , and UO 3 as functions of T, x, and y

  9. Urenco`s experience of UF{sub 6} handling

    Energy Technology Data Exchange (ETDEWEB)

    Saelmans, F. [Urenco Almelo (Netherlands); Scane, C. [Urenco Capenhurst (United Kingdom); Christofzik, J. [Urenco Gronau (Germany)

    1991-12-31

    Urenco operates enrichment plants at three sites, Almelo (Netherlands), Capenhurst (United Kingdom) and Gronau (Germany). Current installed separative work capacity is 2,500 tSWpa. Since 1971, when the first pilot plants were built, enrichment production has totalled 18,000 tSW. During this last 20 years over 3,500 48 containers of UF{sub 6} have been fed to the plants, over 3,700 30 containers have been filled with product and delivered successfully to Urenco`s customers worldwide and over 3,000 48 containers of depleted tails have been filled and have either been returned to customers or retained for long term storage on site. The paper gives a brief outline of Urenco`s experience in handling UF{sub 6}: the equipment and methods used in receiving, feeding, filling, blending, liquid sampling, storing, moving on site and despatching of UF{sub 6} containers. Some of the difficulties experienced with UF{sub 6} containers are appended.

  10. Development of AN Active 238UF6 Gas Target

    Science.gov (United States)

    Eckardt, C.; Enders, J.; Freudenberger, M.; Göök, A.; von Neumann-Cosel, P.; Oberstedt, A.; Oberstedt, S.

    2014-09-01

    Detailed studies of the fission process, e.g., the search for parity nonconservation (PNC) effects, the energy dependence of fission modes or the population of fission isomers, depend on high quality data, therefore requiring high luminosities. An active gas target containing uranium may overcome the deterioration of energy and angular resolution caused by large solid target thicknesses. A single Frisch-grid ionization chamber has been built to test a mixture of standard counting gases (e.g., argon) with depleted uranium hexafluoride (238UF6), utilizing a triple alpha source to evaluate signal quality and drift velocity. For mass fractions of up to 4 percent of 238U the drift velocity increases with rising UF6 content, while a good signal quality and energy resolution is preserved.

  11. Temperature Sensitivity of an Atomic Vapor Cell-Based Dispersion-Enhanced Optical Cavity

    Science.gov (United States)

    Myneni, K.; Smith, D. D.; Chang, H.; Luckay, H. A.

    2015-01-01

    Enhancement of the response of an optical cavity to a change in optical path length, through the use of an intracavity fast-light medium, has previously been demonstrated experimentally and described theoretically for an atomic vapor cell as the intracavity resonant absorber. This phenomenon may be used to enhance both the scale factor and sensitivity of an optical cavity mode to the change in path length, e.g. in gyroscopic applications. We study the temperature sensitivity of the on-resonant scale factor enhancement, S(sub o), due to the thermal sensitivity of the lower-level atom density in an atomic vapor cell, specifically for the case of the Rb-87 D(sub 2) transition. A semi-empirical model of the temperature-dependence of the absorption profile, characterized by two parameters, a(sub o)(T) and gamma(sub a)(T) allows the temperature-dependence of the cavity response, S(sub o)(T) and dS(sub o)/dT to be predicted over a range of temperature. We compare the predictions to experiment. Our model will be useful in determining the useful range for S(sub o), given the practical constraints on temperature stability for an atomic vapor cell.

  12. Synthesis and characterization of a new uranium(V) compound: H3O+UF6-

    International Nuclear Information System (INIS)

    Masson, J.P.; Desmoulin, J.P.; Charpin, P.; Bougon, R.

    1976-01-01

    The reaction of equimolar amounts of UF 5 and H 2 O in hydrogen fluoride results in the partial dissolution of UF 5 , yielding a blue-green solution from which the new salt oxonium hexafluorouranate(V)(H 3 O + UF 6 - ) could be isolated as a green crystalline solid. Calorimetric measurements showed H 3 O + UF 6 - to decompose at about 68 0 C and its heat of formation to be equal to -628 +- 2 kcal mol. Its ionic nature in the solid state and in HF solutions was demonstrated from vibrational and electronic spectra. The electronic spectrum is closely similar to those of LiUF 6 , NaUF 6 , and CsUF 6 and differs from those of RbUF 6 and KUF 6 . This adduct shows a strong ESR signal, with g = -0.78 +- 0.10, characteristic of UF 6 - salts. Based on its x-ray powder diffraction pattern, H 3 O + UF 6 - is cubic with a = 5.2229 +- 0.0005 A

  13. Depleted UF6 programmatic environmental impact statement

    International Nuclear Information System (INIS)

    1997-01-01

    The US Department of Energy has developed a program for long-term management and use of depleted uranium hexafluoride, a product of the uranium enrichment process. As part of this effort, DOE is preparing a Programmatic Environmental Impact Statement (PEIS) for the depleted UF 6 management program. This report duplicates the information available at the web site (http://www.ead.anl.gov/web/newduf6) set up as a repository for the PEIS. Options for the web site include: reviewing recent additions or changes to the web site; learning more about depleted UF 6 and the PEIS; browsing the PEIS and related documents, or submitting official comments on the PEIS; downloading all or part of the PEIS documents; and adding or deleting one's name from the depleted UF 6 mailing list

  14. Rupture of Model 48Y UF6 cylinder and release of uranium hexafluoride. Cylinder overfill, March 12-13, 1986. Investigation of a failed UF6 shipping container. Volume 2

    International Nuclear Information System (INIS)

    1986-06-01

    NUREG-1179, Volume 1, reported on the rupture of a Model 48Y uranium hexafluoride (UF 6 ) cylinder and the subsequent release of UF 6 . At the time of publication, a detailed metallurgical examination of the damaged cylinder was under way and results were not available. Subsequent to the publication of Volume 1, a second incident occurred at the Sequoyah Fuels Corporation facility. On March 13, 1986, a Model 48X cylinder was overfilled during a special one-time draining procedure; however, no release of UF 6 occurred. An Augmented Investigation Team investigated this second incident. This report, NUREG-1179, Volume 2, presents the findings made by the Augmented Investigation Team of the March 13 incident and the report of the detailed metallurgical examination conducted by Battelle Columbus Division of the cylinder damaged on January 4, 1986

  15. Installation for low temperature vapor explosion experiment

    International Nuclear Information System (INIS)

    Nilsuwankosit, Sunchai; Archakositt, Urith

    2000-01-01

    A preparation for the experiment on the low temperature vapor explosion was planned at the department of Nuclear Technology, Chulalongkorn University, Thailand. The objective of the experiment was to simulate the interaction between the molten fuel and the volatile cooling liquid without resorting to the high temperature. The experiment was expected to involve the injection of the liquid material at a moderate temperature into the liquid material with the very low boiling temperature in order to observe the level of the pressurization as a function of the temperatures and masses of the applied materials. For this purpose, the liquid nitrogen and the water were chosen as the coolant and the injected material for this experiment. Due to the size of the installation and the scale of the interaction, only lumped effect of various parameters on the explosion was expected from the experiment at this initial stage. (author)

  16. UF6 breeder reactor power plants for electric power generation

    International Nuclear Information System (INIS)

    Rust, J.H.; Clement, J.D.; Hohl, F.

    1976-01-01

    The reactor concept analyzed is a 233 UF 6 core surrounded by a molten salt (Li 7 F, BeF 2 , ThF 4 ) blanket. Nuclear survey calculations were carried out for both spherical and cylindrical geometries. A maximum breeding ratio of 1.22 was found. Thermodynamic cycle calculations were performed for a variety of Rankine cycles. Optimization of a Rankine cycle for a gas core breeder reactor employing an intermediate heat exchanger gave a maximum efficiency of 37 percent. A conceptual design is presented along with a system layout for a 1000 MW stationary power plant. The advantages of the GCBR are as follows: (1) high efficiency, (2) simplified on-line reprocessing, (3) inherent safety considerations, (4) high breeding ratio, (5) possibility of burning all or most of the long-lived nuclear waste actinides, and (6) possibility of extrapolating the technology to higher temperatures and MHD direct conversion

  17. Enthalpy of sublimation/vaporization of trans-cyclohexyl-1,4-diamine and cis-cyclohexyl-1,2-diamine

    OpenAIRE

    Tomé, Luciana I. N.; Rosado, Mário T. S.; Nunes, Sandra C. C.; Maria, Teresa M. R.; Canotilho, João; Eusébio, M. Ermelinda S.

    2007-01-01

    The molar enthalpy of sublimation, , of trans-cyclohexyl-1,4-diamine and the molar enthalpy of vaporization, , of cis-cyclohexyl-1,2-diamine, at the temperature 298.15 K, were determined by calorimetry. was obtained for the trans-isomer and for the cis form. The molar enthalpy of fusion of the first compound, at T = 342.1 K, was determined by differential scanning calorimetry. The molar enthalpy of vaporization of the 1,4-isomer was estimated by combining the value of the enthalpy of sublimat...

  18. Whole-body voxel phantoms of paediatric patients—UF Series B

    Science.gov (United States)

    Lee, Choonik; Lee, Choonsik; Williams, Jonathan L.; Bolch, Wesley E.

    2006-09-01

    Following the previous development of the head and torso voxel phantoms of paediatric patients for use in medical radiation protection (UF Series A), a set of whole-body voxel phantoms of paediatric patients (9-month male, 4-year female, 8-year female, 11-year male and 14-year male) has been developed through the attachment of arms and legs from segmented CT images of a healthy Korean adult (UF Series B). Even though partial-body phantoms (head-torso) may be used in a variety of medical dose reconstruction studies where the extremities are out-of-field or receive only very low levels of scatter radiation, whole-body phantoms play important roles in general radiation protection and in nuclear medicine dosimetry. Inclusion of the arms and legs is critical for dosimetry studies of paediatric patients due to the presence of active bone marrow within the extremities of children. While the UF Series A phantoms preserved the body dimensions and organ masses as seen in the original patients who were scanned, comprehensive adjustments were made for the Series B phantoms to better match International Commission on Radiological Protection (ICRP) age-interpolated reference body masses, body heights, sitting heights and internal organ masses. The CT images of arms and legs of a Korean adult were digitally rescaled and attached to each phantom of the UF series. After completion, the resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year and 14-year were set at 0.86 mm × 0.86 mm × 3.0 mm, 0.90 mm × 0.90 mm × 5.0 mm, 1.16 mm × 1.16 mm × 6.0 mm, 0.94 mm × 0.94 mm × 6.00 mm and 1.18 mm × 1.18 mm × 6.72 mm, respectively.

  19. Hydraulic breakage of tanks for the transport of uranium hexafluoride (UF6)

    International Nuclear Information System (INIS)

    Biaggio, A.L.; Lee Gonzales, H.M.; Lopez Vietri, J.R.; Novo, R.G.

    1987-01-01

    To begin with, the tank models that are proposed by the international norms for the transport and storage of hexafluoride of uranium (UF 6 ) are briefly described. The operations related to the transport in its different forms are also described, particularly those that can produce the hydraulic breakage of tanks during its course or in later stages, when incorrectly performed. With reference to those operations, the most important physicochemical properties of UF 6 as for safety are analyzed. A quantitative evaluation of the deviations of parameters that are controlled during the heating of tanks, comparing them with the normative nominal values, is performed. Adopting some simplifying hypothesis, a general study, applicable to all tank models proposed by norms, is carried out to determine the temperature at which the hydraulic breakage takes place when they are heated in closed-valve conditions. A curve is obtained by plotting the hydraulic breakage temperature against the filling degree. To conclude, the values obtained are compared with the results of other theoretical studies on this subject. (Author)

  20. Thermodynamic data for uranium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Leitnaker, J.M.

    1983-03-01

    Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF/sub 4/ and UF/sub 6/, including UF/sub 4/ (solid and gas), U/sub 4/F/sub 17/ (solid), U/sub 2/F/sub 9/ (solid), UF/sub 5/ (solid and gas), U/sub 2/F/sub 10/ (gas), and UF/sub 6/ (solid, liquid, and gas). Included are thermal function - the heat capacity, enthalpy, and free energy function, heats of formation, and vaporization behavior.

  1. Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid

    DEFF Research Database (Denmark)

    Rodier, Marion; Li, Qingfeng; Berg, Rolf W.

    2016-01-01

    A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed...... with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available...... in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case...

  2. Argon/UF6 plasma exhaust gas reconstitution experiments using preheated fluorine and on-line diagnostics. [fissioning uranium plasma core reactor design

    Science.gov (United States)

    Roman, W. C.

    1979-01-01

    The feasibility of employing a flowing, high-temperature, pure fluorine/UF6 regeneration system to efficiently convert a large fraction of the effluent plasma exhaust back to pure UF6 was demonstrated. The custom built T.O.F. mass spectrometer sampling system permitted on-line measurements of the UF6 concentration at different locations in the exhaust system. Negligible amounts ( 100 ppm) of UF6 were detected in the axial bypass exhaust duct and the exhaust ducts downstream of the cryogenic trap system used to collect the UF6, thus verifying the overall system efficiency over a range of operating conditions. Use of a porous Monel duct as part of the exhaust duct system, including provision for injection of pure fluorine, provided a viable technique to eliminate uranium compound residue on the inside surface of the exhaust ducts. Typical uranium compound mass deposition per unit area of duct was 2 micron g/sq cm. This porous duct technique is directly applicable to future uranium compound transfer exhaust systems. Throughout these experiments, additional basic data on the corrosion aspects of hot, pressurized UF6/fluorine were also accumulated.

  3. Temperature/pressure and water vapor sounding with microwave spectroscopy

    Science.gov (United States)

    Muhleman, D. O.; Janssen, M. A.; Clancy, R. T.; Gulkis, S.; Mccleese, D. J.; Zurek, R.; Haberle, R. M.; Frerking, M.

    1992-01-01

    Two intense microwave spectra lines exist in the martian atmosphere that allow unique sounding capabilities: water vapor at 183 GHz and the (2-1) rotational line of CO at 230 GHz. Microwave spectra line sounding is a well-developed technique for the Earth's atmosphere for sounding from above from spacecraft and airplanes, and from below from fixed surface sites. Two simple instruments for temperature sounding on Mars (the CO line) and water vapor measurements are described. The surface sounder proposed for the MESUR sites is designed to study the boundary layer water vapor distribution and the temperature/pressure profiles with vertical resolution of 0.25 km up to 1 km with reduced resolution above approaching a scale height. The water channel will be sensitive to a few tenths of a micrometer of water and the temperature profile will be retrieved to an accuracy between 1 and 2 K. The latter is routinely done on the Earth using oxygen lines near 60 GHz. The measurements are done with a single-channel heterodyne receiver looking into a 10-cm mirror that is canned through a range of elevation angles plus a target load. The frequency of the receiver is sweep across the water and CO lines generating the two spectra at about 1-hr intervals throughout the mission. The mass and power for the proposed instrument are 2 kg and 5-8 W continuously. The measurements are completely immune to the atmospheric dust and ice particle loads. It was felt that these measurements are the ultimate ones to properly study the martian boundary layer from the surface to a few kilometers. Sounding from above requires an orbiting spacecraft with multichannel microwave spectrometers such as the instrument proposed for MO by a subset of the authors, a putative MESUR orbiter, and a proposed Discovery mission called MOES. Such an instrument can be built with less than 10 kg and use less than 15 W. The obvious advantage of this approach is that the entire atmosphere can be sounded for temperature and

  4. Room-temperature synthesis of ultraviolet-emitting nanocrystalline GaN films using photochemical vapor deposition

    International Nuclear Information System (INIS)

    Yamazaki, Shunsuke; Yatsui, Takashi; Ohtsu, Motoichi; Kim, Taw-Won; Fujioka, Hiroshi

    2004-01-01

    We fabricated UV-emitting nanocrystalline gallium nitride (GaN) films at room temperature using photochemical vapor deposition (PCVD). For the samples synthesized at room temperature with V/III ratios exceeding 5.0x10 4 , strong photoluminescence peaks at 3.365 and 3.310 eV, which can be ascribed to transitions in a mixed phase of cubic and hexagonal GaN, were observed at 5 K. A UV emission spectrum with a full width at half-maximum of 100 meV was observed, even at room temperature. In addition, x-ray photoelectron spectroscopy measurement revealed that the film deposited by PCVD at room temperature was well nitridized

  5. Investigating the effects of methanol-water vapor mixture on a PBI-based high temperature PEM fuel cell

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Andreasen, Søren Juhl; Nielsen, Heidi Venstrup

    2012-01-01

    This paper investigates the effects of methanol and water vapor on the performance of a high temperature proton exchange membrane fuel cell (HT-PEMFC). A H3PO4-doped polybenzimidazole (PBI) membrane electrode assembly (MEA), Celtec P2100 of 45 cm2 of active surface area from BASF was employed....... A long-term durability test of around 1250 h was performed, in which the concentrations of methanol-water vapor mixture in the anode feed gas were varied. The fuel cell showed a continuous performance decay in the presence of vapor mixtures of methanol and water of 5% and 8% by volume in anode feed...

  6. Magnesio-thermic reduction of UF4 to uranium metal : plant operating experience

    International Nuclear Information System (INIS)

    Mayekar, S.V.; Singh, H.; Meghal, A.M.; Koppiker, K.S.

    1991-01-01

    Uranium Metal Plant has switched over from calcio-thermy to magnesio-thermy for production of uranium ingots. In this paper, the plant operating experience for magnesio-thermic reduction is described. Based on trials, the production has been stepped up from 40 kg ingots to 200 kg ingots. The operating parameters optimised include : heating schedule, UF 4 quality, magnesium quantity and quality, and particle size. The effect of quality of refractory lining has been discussed. Conditions for lining are optimised with regard to type of material used and size. Developmental work has also been carried out on use of pelletised charge and on use of graphite sleeves. Some experience in the machining of ingots for removal of surface slag is also discussed. Impurity problems, occasionally encountered, have been investigated and results are discussed. Based on the experience gained, specifications for operation have been laid down, and areas for further improvement are identified. (author). 5 refs., 1 fig., 1 tab

  7. Temperature and saturation dependence in the vapor sensing of butterfly wing scales

    Energy Technology Data Exchange (ETDEWEB)

    Kertész, K., E-mail: kertesz.krisztian@ttk.mta.hu [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49 (Hungary); Piszter, G. [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49 (Hungary); Jakab, E. [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, H-1525 Budapest, P O Box 17 (Hungary); Bálint, Zs. [Hungarian Natural History Museum, H-1088, Budapest, Baross utca 13 (Hungary); Vértesy, Z.; Biró, L.P. [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49 (Hungary)

    2014-06-01

    The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. - Highlights: • We report optical gas sensing on blue butterfly wing scale nanostructures. • The sample temperature decrease effects a reversible break-down in the measured spectra. • The break-down is connected with the vapor condensation in the scales and wing surface. • Capillary condensation occurs in the wing scales.

  8. Temperature and saturation dependence in the vapor sensing of butterfly wing scales

    International Nuclear Information System (INIS)

    Kertész, K.; Piszter, G.; Jakab, E.; Bálint, Zs.; Vértesy, Z.; Biró, L.P.

    2014-01-01

    The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. - Highlights: • We report optical gas sensing on blue butterfly wing scale nanostructures. • The sample temperature decrease effects a reversible break-down in the measured spectra. • The break-down is connected with the vapor condensation in the scales and wing surface. • Capillary condensation occurs in the wing scales

  9. Vapor pressure and enthalpy of vaporization of aliphatic propanediamines

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Chernyak, Yury

    2012-01-01

    Highlights: ► We measured vapor pressure of four aliphatic 1,3-diamines. ► Vaporization enthalpies at 298 K were derived. ► We examined consistency of new and available data in the literature. ► A group-contribution method for prediction was developed. - Abstract: Vapor pressures of four aliphatic propanediamines including N-methyl-1,3-propanediamine (MPDA), N,N-dimethyl-1,3-propanediamine (DMPDA), N,N-diethyl-1,3-propanediamine (DEPDA) and N,N,N′,N′-tetramethyl-1,3-propanediamine (4MPDA) were measured using the transpiration method. The vapor pressures developed in this work and reported in the literature were used to derive molar enthalpy of vaporization values at the reference temperature 298.15 K. An internal consistency check of the enthalpy of vaporization was performed for the aliphatic propanediamines studied in this work. A group-contribution method was developed for the validation and prediction vaporization enthalpies of amines and diamines.

  10. HEU to LEU Conversion and Blending Facility: UF{sub 6} blending alternative to produce LEU UF{sub 6} for commercial use

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    US DOE is examining options for disposing of surplus weapons-usable fissile materials and storage of all weapons-usable fissile materials; the nuclear material will be converted to a form more proliferation- resistant than the original form. Examining options for increasing the proliferation resistance of highly enriched uranium (HEU) is part of this effort. Five technologies for blending HEU will be assessed; blending as UF{sub 6} to produce a UF{sub 6} product for commercial use is one of them. This document provides data to be used in the environmental impact analysis for the UF{sub 6} blending HEU disposition option. Resource needs, employment needs, waste and emissions from plant, hazards, accident scenarios, and intersite transportation are discussed.

  11. Application of fixed bed trapping technology for the removal of low concentration UF6 from plant gaseous effluent streams

    International Nuclear Information System (INIS)

    Russell, R.G.

    1987-01-01

    For the trapping of UF 6 in nitrogen, NaF > Al 2 O 3 > CaSO 4 . UF 6 inlet concentration has little effect on loading of alumina. Velocity shows an effect on UF 6 loading on alumina, with higher loading at low velocity. There is no significant difference in UF 6 loading between alumina 201A and 202HF. UF 6 outlet concentrations prior to breakthrough were measured to be as low as 2 O 3 until breakthrough (6.6% vs 5.3%), after which NaF experiences more loading (7.5% vs 11.5% at 1 ppM in the outlet). Higher trap loadings at lower pressures for both NaF and Al 2 O 3 . Al 2 O 3 was more efficient than NaF at higher velocities

  12. Safety provisions for UF{sub 6} handling in the design of a new UF{sub 6} conversion plant

    Energy Technology Data Exchange (ETDEWEB)

    Bannister, S.P. [British Nuclear Fuels plc, Preston (United Kingdom)

    1991-12-31

    British Nuclear Fuels plc (BNFL) Fuel Division is currently undertaking the final design and construction of a new UF{sub 6} conversion plant at its production site at Springfields near Preston in the north of England. The Company has gained much experience in the handling of UF{sub 6} during operation of plants on site since 1961. The major hazard occurs during the liquefication cycle and the basis of the maximum credible incident scenario adopted for safety assessment and design purposes is discussed. This paper considers the design features which have been incorporated in the new plant to counter the hazards presented by the presence of UF{sub 6} in gaseous and liquid form and explains current thinking on operational procedures in areas of potential risk such as cylinder filling. The plant emergency response philosophy and systems are described and specific design provisions which have been included to satisfy the UK regulatory bodies are outlined in some detail.

  13. Assessing the Temperature Dependence of Narrow-Band Raman Water Vapor Lidar Measurements: A Practical Approach

    Science.gov (United States)

    Whiteman, David N.; Venable, Demetrius D.; Walker, Monique; Cardirola, Martin; Sakai, Tetsu; Veselovskii, Igor

    2013-01-01

    Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author.

  14. Physical vapor transport growth and properties of SiC monocrystals of 4H polytype

    Energy Technology Data Exchange (ETDEWEB)

    Augustine, G.; Hobgood, H.M.; Balakrishna, V.; Dunne, G.; Hopkins, R.H. [Northrop Grumman Corp., Pittsburgh, PA (United States). Electron. Sensors and Syst. Div.

    1997-07-01

    The physical vapor transport technique can be employed to fabricate large diameter silicon carbide crystals (up to 50 mm diameter) exhibiting uniform 4H-polytype over the full crystal volume. Crystal growth rate is controlled to first order by temperature conditions and ambient pressure. 4H-polytype uniformity is controlled by polarity of the seed crystal and the growth temperature. 4H-SiC crystals exhibit crystalline defects mainly in the form of dislocations with densities in the 10{sup 4} cm{sup -2} range and micropipe defects, the latter having densities as low as 10 cm{sup -2} in best crystals. Electrical conductivity in 4H-SiC bulk crystals ranges from <10{sup -2} {Omega} cm, n-type, to insulating (>10{sup 15} {Omega} cm) at room temperature. (orig.) 33 refs.

  15. Corrosion of breached UF6 storage cylinders

    International Nuclear Information System (INIS)

    Barber, E.J.; Taylor, M.S.; DeVan, J.H.

    1993-01-01

    This paper describes the corrosion processes that occurred following the mechanical failure of two steel 14-ton storage cylinders containing depleted UF 6 . The failures both were traced to small mechanical tears that occurred during stacking of the cylinders. Although subsequent corrosion processes greatly extended the openings in the wall. the reaction products formed were quite protective and prevented any significant environmental insult or loss of uranium. The relative sizes of the two holes correlated with the relative exposure times that had elapsed from the time of stacking. From the sizes and geometries of the two holes, together with analyses of the reaction products, it was possible to determine the chemical reactions that controlled the corrosion process and to develop a scenario for predicting the rate of hydrolysis of UF 6 , the loss rate of HF, and chemical attack of a breached UF 6 storage cylinder

  16. Isosteric Vapor Pressure – Temperature Data for Water Sorption in Hardened Cement Paste: Enthalpy, Entropy and Sorption Isotherms at Different Temperatures

    DEFF Research Database (Denmark)

    Radjy, Fariborz; Sellevold, Erik J.; Hansen, Kurt Kielsgaard

    . The accuracies for pressure, enthalpy and entropy are found to be 0.5% or less. PART II: The TPA-system has been used to generate water vapor pressure – temperature data for room temperature – and steam cured hardened cement pastes as well as porous vycor glass. The moisture contents range from saturated to dry...... and the temperatures range from 2 to 95 °C, differing for the specimen types. The data has been analyzed to yield differential enthalpy and entropy of adsorption, as well as the dependence of the relative vapor pressure on temperature at various constant moisture contents. The implications for the coefficient......PART I: In order to generate isosteric (constant mass) vapor pressure – temperature data (P-T data) for adsorbed pore water in hydrated cement paste, the Thermo Piestic Analysis system (the TPA system) described herein was developed. The TPA system generates high precision equilibrium isosteric P...

  17. Ultra-low field NMR for detection and characterization of 235 UF6

    Energy Technology Data Exchange (ETDEWEB)

    Espy, Michelle A [Los Alamos National Laboratory; Magnelind, Per E [Los Alamos National Laboratory; Matlashov, Andrei N [Los Alamos National Laboratory; Urbaitis, Algis V [Los Alamos National Laboratory; Volegov, Petr L [Los Alamos National Laboratory

    2009-01-01

    We have demonstrated the first ultra-low field (ULF) nuclear magnetic resonance measurements of uranium hexafluoride (UF{sub 6}), both depleted and 70% enriched, which is used in the uranium enrichment process. A sensitive non-invasive detection system would have an important role in non-proliferation surveillance. A two-frequency technique was employed to remove the transients induced by rapidly switching off the 50 mT pre-polarization field. A mean transverse relaxation time T{sub 2} of 24 ms was estimated for the un-enriched UF{sub 6} sample measured at a mean temperature of 80 C. Nuclear magnetic resonance at ULF has several advantages including the ability to measure through metal, such as pipes, and simple magnetic field generation hardware. We present here recent data and discuss the potential for non-proliferation monitoring of enrichment and flow velocity.

  18. MF/UF rejection and fouling potential of algal organic matter from bloom-forming marine and freshwater algae

    KAUST Repository

    Villacorte, Loreen O.; Ekowati, Yuli; Winters, Harvey; Amy, Gary L.; Schippers, Jan Cornelis; Kennedy, Maria Dolores

    2015-01-01

    the latter were poorly rejected. MF (0.4μm and 0.1μm pore size) rejected 14%-56% of biopolymers while conventional UF (100kDa) and tight UF (10kDa) rejected up to 83% and 97%, respectively. The retention of AOM resulted in a rapid increase in trans

  19. Forsterite Shock Temperatures and Entropy: New Scaling Laws for Impact Melting and Vaporization

    Science.gov (United States)

    Davies, E.; Root, S.; Kraus, R. G.; Townsend, J. P.; Spaulding, D.; Stewart, S. T.; Jacobsen, S. B.; Fratanduono, D.; Millot, M. A.; Mattsson, T. R.; Hanshaw, H. L.

    2017-12-01

    The observed masses, radii and temperatures of thousands of extra-solar planets have challenged our theoretical understanding of planet formation and planetary structures. Planetary materials are subject to extreme pressures and temperatures during formation and within the present-day interiors of large bodies. Here, we focus on improving understanding of the physical properties of rocky planets for calculations of internal structure and the outcomes of giant impacts. We performed flyer plate impact experiments on forsterite [Mg2SiO4] on the Z-Machine at Sandia National Laboratory and decaying shock temperature measurements at the Omega EP laser at U. Rochester. At Z, planar, supported shock waves are generated in single crystal samples, permitting observation of both compressed and released states. Using available static and dynamic thermodynamic data, we calculate absolute entropy and heat capacity along the forsterite shock Hugoniot. Entropy and heat capacity on the Hugoniot are larger than previous estimates. Our data constrain the thermodynamic properties of forsterite liquid at high pressures and temperatures and the amount of melt and vapor produced during impact events. For an ambient pressure of 1 bar, shock-vaporization begins upon reaching the liquid region on the forsterite Hugoniot (about 200 GPa). Using hydrocode simulations of giant impacts between rocky planets with forsterite mantles and iron cores and the new experimentally-constrained forsterite shock entropy, we present a new scaling law for the fraction of mantle that is melted or vaporized by the initial shock wave. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. Prepared by LLNL under Contract DE-AC52-07NA27344. Prepared by the Center

  20. UF6 Cylinder Imaging by Fast Neutron Transmission Tomography

    International Nuclear Information System (INIS)

    McElroy, R.; Hausladen, P.; Blackston, M.; Croft, S.

    2015-01-01

    The common use Non-Destructive Assay techniques for the determination of 235 U enrichment and mass of UF6 cylinders used in the production of nuclear reactor fuel require prior knowledge of the physical distribution of the UF6 within the cylinder. The measurement performance for these techniques is typically evaluated based on assumed bounding case distributions of the material. However, little direct data such as radiographic or tomographic images, regarding the distribution of the UF6 within the cylinder is available against which to judge these assumptions. We have developed and tested a prototype active neutron tomographic imaging system employing an Associated Particle Imaging (API) neutron generator and an array of pixelated neutron scintillation counters. This system has been successfully used to obtain the 3-dimensional map of the distribution of UF6 within a type 12B storage cylinder. Results from these measurements are presented and the potential performance and utility of this technique with larger 30B and 48Y cylinders is discussed. (author)

  1. Vaporization, fusion and sublimation enthalpies of the dicarboxylic acids from C4 to C14 and C16

    International Nuclear Information System (INIS)

    Roux, Maria Victoria; Temprado, Manuel; Chickos, James S.

    2005-01-01

    The fusion enthalpies of the series butanedioic acid through to tetradecanedioic acid and hexadecanedioic acids have been measured by DSC. In addition to fusion, a number of solid-solid phase transitions have also been detected in these diacids. The vaporization enthalpies of these compounds have been measured by correlation gas chromatography using the vaporization enthalpies of butanedioic, hexanedioic and decanedioic acids as standards. The vaporization enthalpies of the diacids from C 4 to C 10 correlated linearly with the number of methylene groups present. Above C 10 , the vaporization enthalpies of C 11 -C 14 and C 16 begin to deviate from linearity. The vaporization enthalpies for these compounds are dependent on the temperature of the GC column used. Similar departure from linearity has also been observed previously in the sublimation enthalpies for these compounds. The results are discussed in terms of formation of a cyclic intramolecular hydrogen bonded network in the gas phase similar to the bimolecular association observed in smaller mono-carboxylic acids at ambient temperatures

  2. High temperature vaporization/decomposition studies of lanthanide and actinide fluorides

    International Nuclear Information System (INIS)

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

    1987-01-01

    Binary fluorides of the lanthanide and actinide elements comprise a fundamental class of compounds. The authors' investigations of their basic high temperature vaporization and/or decomposition behavior are aimed at elucidating more fully the thermal properties of selected tri- and tetrafluorides and extending such investigations to fluorides which have not been studied previously. Depending on the particular system and the specific experimental conditions, the authors' measurements can provide such information as the enthalpy associated with a congruent vaporization process and/or the relative stabilities of fluorides containing a lanthanide/actinide element in different oxidation states. The authors are also studying the congruent vaporization of selected lanthanide trifluorides with particular emphasis on two areas. The first concerns the variation in the enthalpies of sublimation of the trifluorides across the lanthanide series. Although this variation is rather small (δ5 kcal where ΔH/sub subl/ is approximately 100 kcal), it is larger than observed for other lanthanide trihalides and is unusually irregular. To examine this reported variation more closely, they are attempting to measure relative vapor pressures/enthalpies of vaporization by studying mixtures of two or more lanthanide trifluorides by the technique discussed above

  3. A new method for the determination of vaporization enthalpies of ionic liquids at low temperatures.

    Science.gov (United States)

    Verevkin, Sergey P; Zaitsau, Dzmitry H; Emelyanenko, Vladimir N; Heintz, Andreas

    2011-11-10

    A new method for the determination of vaporization enthalpies of extremely low volatile ILs has been developed using a newly constructed quartz crystal microbalance (QCM) vacuum setup. Because of the very high sensitivity of the QCM it has been possible to reduce the average temperature of the vaporization studies by approximately 100 K in comparison to other conventional techniques. The physical basis of the evaluation procedure has been developed and test measurements have been performed with the common ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C(2)mim][NTf(2)] extending the range of measuring vaporization enthalpies down to 363 K. The results obtained for [C(2)mim][NTf(2)] have been tested for thermodynamic consistency by comparison with data already available at higher temperatures. Comparison of the temperature-dependent vaporization enthalpy data taken from the literature show only acceptable agreement with the heat capacity difference of -40 J K(-1) mol(-1). The method developed in this work opens also a new way to obtain reliable values of vaporization enthalpies of thermally unstable ionic liquids.

  4. Properties of water along the liquid-vapor coexistence curve via molecular dynamics simulations using the polarizable TIP4P-QDP-LJ water model.

    Science.gov (United States)

    Bauer, Brad A; Patel, Sandeep

    2009-08-28

    We present an extension of the TIP4P-QDP model, TIP4P-QDP-LJ, that is designed to couple changes in repulsive and dispersive nonbond interactions to changes in polarizability. Polarizability is intimately related to the dispersion component of classical force field models of interactions, and we explore the effect of incorporating this connection explicitly on properties along the liquid-vapor coexistence curve of pure water. Parametrized to reproduce condensed-phase liquid water properties at 298 K, the TIP4P-QDP-LJ model predicts density, enthalpy of vaporization, self-diffusion constant, and the dielectric constant at ambient conditions to about the same accuracy as TIP4P-QDP but shows remarkable improvement in reproducing the liquid-vapor coexistence curve. TIP4P-QDP-LJ predicts critical constants of T(c)=623 K, rho(c)=0.351 g/cm(3), and P(c)=250.9 atm, which are in good agreement with experimental values of T(c)=647.1 K, rho(c)=0.322 g/cm(3), and P(c)=218 atm, respectively. Applying a scaling factor correction (obtained by fitting the experimental vapor-liquid equilibrium data to the law of rectilinear diameters using a three-term Wegner expansion) the model predicts critical constants (T(c)=631 K and rho(c)=0.308 g/cm(3)). Dependence of enthalpy of vaporization, self-diffusion constant, surface tension, and dielectric constant on temperature are shown to reproduce experimental trends. We also explore the interfacial potential drop across the liquid-vapor interface for the temperatures studied. The interfacial potential demonstrates little temperature dependence at lower temperatures (300-450 K) and significantly enhanced (exponential) dependence at elevated temperatures. Terms arising from the decomposition of the interfacial potential into dipole and quadrupole contributions are shown to monotonically approach zero as the temperature approaches the critical temperature. Results of this study suggest that self-consistently treating the coupling of phase

  5. Computer modeling of the sensitivity of a laser water vapor sensor to variations in temperature and air speed

    Science.gov (United States)

    Tucker, George F.

    1994-01-01

    Currently, there is disagreement among existing methods of determining atmospheric water vapor concentration at dew-points below -40 C. A major source of error is wall effects which result from the necessity of bringing samples into the instruments. All of these instruments also have response times on the order of seconds. NASA Langley is developing a water vapor sensor which utilizes the absorption of the infrared radiation produced by a diode laser to estimate water vapor concentration. The laser beam is directed through an aircraft window to a retroreflector located on an engine. The reflected beam is detected by an infrared detector located near the laser. To maximize signal to noise, derivative signals are analyzed. By measuring the 2f/DC signal and correcting for ambient temperature, atmospheric pressure and air speed (which results in a Doppler shifting of the laser beam), the water vapor concentration can be retrieved. Since this is an in situ measurement there are no wall effects and measurements can be made at a rate of more than 20 per second. This allows small spatial variations of water vapor to be studied. In order to study the sensitivity of the instrument to variations in temperature and air speed, a computer program which generated the 2f, 3f, 4f, DC and 2f/DC signals of the instrument as a function of temperature, pressure and air speed was written. This model was used to determine the effect of errors in measurement of the temperature and air speed on the measured water vapor concentration. Future studies will quantify the effect of pressure measurement errors, which are expected to be very small. As a result of these studied, a retrieval algorithm has been formulated, and will be applied to data taken during the PEM-West atmospheric science field mission. Spectroscopic studies of the water vapor line used by the instrument will be used to refine this algorithm. To prepare for these studies, several lasers have been studied to determine their

  6. Photochemical removal of NpF6 and PuF6 from UF6 gas streams

    International Nuclear Information System (INIS)

    Beitz, J.V.; Williams, C.W.

    1990-01-01

    A novel photochemical method of removing reactive fluorides from UF 6 gas has been discovered. This method reduces generated waste to little more than the volume of the removed impurities, minimizes loss of UF 6 , and can produce a recyclable by-product, fluorine gas. In our new method, impure UF 6 , is exposed to ultraviolet light which dissociates the UF 6 to UF 5 and fluorine atom. Impurities which chemically react with UF 5 are reduced and form solid compounds easily removed from the gas while UF 5 is converted back to UF 6 . Proof-of-concept testing involved UF 6 containing NpF 6 and PuF 6 with CO added as a fluorine atom scavenger. In a single photolysis step, greater than 5000-fold reduction of PuF 6 was demonstrated while reducing NpF 6 by more than 40-fold. This process is likely to remove corrosion and fission product fluorides that are more reactive than UF 6 and has been demonstrated without an added fluorine atom scavenger by periodically removing photogenerated fluorine gas. 44 refs., 3 figs., 2 tabs

  7. Vaporization of liquid Pb-Li eutectic alloy from 1000K to 1200K - A high temperature mass spectrometric study

    Science.gov (United States)

    Jain, U.; Mukherjee, A.; Dey, G. K.

    2017-09-01

    Liquid lead-lithium eutectic will be used as a coolant in fusion reactor blanket loop. Vapor pressure of the eutectic is an important parameter to accurately predict its in-loop behavior. Past measurements of vapor pressure of the eutectic relied on indirect methods. In this paper, we report for the first time the in-situ vaporization behavior of the liquid alloy between 1042 and 1176 K by Knudsen effusion mass spectrometry (KEMS). It was seen that the vaporization occurred by independent evaporation of lead and lithium. No complex intermetallic vapor was seen in the mass spectra. The partial pressures and enthalpy of vaporization of Pb and Li were evaluated directly from the measured ion intensities formed from the equilibrium vapor over the alloy. The activity of Li over a temperature range of 1042-1176 K was found to be 4.8 × 10-5 to that of pure Li, indicating its very low activity in the alloy.

  8. Single-footprint retrievals of temperature, water vapor and cloud properties from AIRS

    Science.gov (United States)

    Irion, Fredrick W.; Kahn, Brian H.; Schreier, Mathias M.; Fetzer, Eric J.; Fishbein, Evan; Fu, Dejian; Kalmus, Peter; Wilson, R. Chris; Wong, Sun; Yue, Qing

    2018-02-01

    Single-footprint Atmospheric Infrared Sounder spectra are used in an optimal estimation-based algorithm (AIRS-OE) for simultaneous retrieval of atmospheric temperature, water vapor, surface temperature, cloud-top temperature, effective cloud optical depth and effective cloud particle radius. In a departure from currently operational AIRS retrievals (AIRS V6), cloud scattering and absorption are in the radiative transfer forward model and AIRS single-footprint thermal infrared data are used directly rather than cloud-cleared spectra (which are calculated using nine adjacent AIRS infrared footprints). Coincident MODIS cloud data are used for cloud a priori data. Using single-footprint spectra improves the horizontal resolution of the AIRS retrieval from ˜ 45 to ˜ 13.5 km at nadir, but as microwave data are not used, the retrieval is not made at altitudes below thick clouds. An outline of the AIRS-OE retrieval procedure and information content analysis is presented. Initial comparisons of AIRS-OE to AIRS V6 results show increased horizontal detail in the water vapor and relative humidity fields in the free troposphere above the clouds. Initial comparisons of temperature, water vapor and relative humidity profiles with coincident radiosondes show good agreement. Future improvements to the retrieval algorithm, and to the forward model in particular, are discussed.

  9. Level 4 Milestone (M4): M41UF033201 - Review of Radiolysis of Brines on the Surface of a Waste Package

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Mark [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-08-12

    This milestone report (M41UF033201) documents a literature review of relevant publications for gamma radiolysis occurring within a droplet of water on the outside of a waste package in a repository environment within the “

  10. SnO2 thin film synthesis for organic vapors sensing at ambient temperature

    Directory of Open Access Journals (Sweden)

    N.H. Touidjen

    2016-12-01

    Full Text Available The present work is a study of tin dioxide (SnO2 based thin sensitive layer dedicated to organic vapors detection at ambient temperature. SnO2 thin film was deposited by chemical spray pyrolysis technique. The glass substrate temperature was kept to 400 °C, using a starting solution of 0.1 M tin (II dichloride dihydrate (SnCl2, 2H2O. Films structural and morphological properties were characterized using X-ray diffraction (XRD, scanning electron microscopy (SEM and atomic force microscope (AFM respectively. Films optical characteristics were studied using UV-VIS spectrophotometer. XRD revealed the presence of pure SnO2 polycrystalline thin film with a tetragonal rutile structure. The SEM and AFM observations confirmed the granular morphology with presence of pores in the film surface. The prepared film was tested in various organic vapors (ethanol, methanol and acetone at ambient operating temperature (25 °C ± 2 °C. The obtained results suggested that SnO2 is more sensitive to ethanol vapor with a maximum sensitivity of 35% higher than to methanol and acetone vapors (1% and 3%. The realized SnO2 based sensor demonstrated fast response and recovery times as revealed by the values of 2 s to 3 s towards 47 ppm of ethanol vapor. Keywords: SnO2 thin film, Sensitivity, XRD, SEM, AFM, UV–visible

  11. Thermodynamic properties of a high pressure subcritical UF6He gas volume (irradiated by an external source)

    International Nuclear Information System (INIS)

    Sterritt, D.E.; Lalos, G.T.; Schneider, R.T.

    1976-12-01

    A computer simulation study concerning a compressed fissioning UF 6 gas is presented. The compression is to be achieved by a ballistic piston compressor. Data on UF 6 obtained with this compressor were incorporated in the simulation study. As a neutron source to create the fission events in the compressed gas, a fast burst reactor was considered. The conclusion is that it takes a neutron flux in excess of 10 15 n/cm 2 -s to produce measurable increases in pressure and temperature, while a flux in excess of 10 19 n/cm 2 -s would probably damage the compressor

  12. Chemically vapor-deposited tungsten: its high temperature strength and ductility

    International Nuclear Information System (INIS)

    Bryant, W.A.

    1977-01-01

    The high temperature tensile ductility (as measured by total elongation normal to the growth direction) of chemically vapor-deposited tungsten was found to be significantly greater than previously reported. A correlation was found between ductility and void content. However, voids were found to have essentially no effect on the high temperature strength of this material, which is considerably weaker than powder metallurgy tungsten. (Auth.)

  13. Determination of UO2F2, UO2 and UF4 in tetrafluoride of uranium samples

    International Nuclear Information System (INIS)

    Contreras Guzman, Ariel; Arlegui Hormazabal, Oscar

    2003-01-01

    The combustible elements for investigation reactors that at the present are manufacturing by the Chilean Nuclear Energy Commission (CCHEN) they are based on aluminum and silicide uranium powdered which is obtained from metallic uranium. At the present the Conversion Units, is developing the technology of transformation UF 6 in metallic Uranium, reason for which is necessary that the Chemical Analysis Laboratory have a methodology that allows to quantify the presence of UO 2 F 2 , UO 2 and UF 4 in the samples obtained in this transformation process. For this reason we are implements the methodology of sequential analysis that had been developed previously, for the Institute of Energy and Nuclear Investigations, IPEN Brasil, and to adapt it to the present conditions in the Laboratory of Chemical Analysis of the CCHEN. This method is based on the different solubilities that present those sample in front of solvents as ethanol and solutions of ammonium oxalate, what allows the separation of these compounds for a later analysis by means of the method of Davies and Gray. This method is based on the reduction of the uranium (VI) to uranium (IV) with ferrous ion amid phosphoric acid, quantifying the present uranium in the samples by means of titration with potassium dicromate. With the purpose of checking the efficiency of the method, the sum of all values of uranium coming from each compound and compares it with the total uranium of the sample (author)

  14. Improvement of Oil-Vapor Treatment Facility for Wolsong Unit 3,4

    International Nuclear Information System (INIS)

    Kim, Jeong Guk; Kwon, S. W.; Lee, H. S.

    2009-11-01

    With the purpose to minimize an oil-vapor discharge to the atmosphere and to be an environmentally friendly nuclear power plant by an improvement of mist eliminator for turbine lubricant system at Wolsong Nuclear Power Plant Unit 3,4, this project - project name : Improvement of Oil-vapor Treatment Facility for Wolsong Unit 3,4 - was conducted for six months (from Apr. 15, 2009 to Oct. 14, 2009). This Project contains Oil-vapor Source and Environmental Regulation, Analysis on the Present Oil-vapor Treatment Facility, Improvement of Oil-vapor Treatment Facility, Test Facility Design, Fabrication, Installation, Test Operation, Evaluation of the Facility

  15. Salts purification and redox potential measurement for the molten LiF-ThF4-UF4 mixture

    International Nuclear Information System (INIS)

    Afonichkin, V.; Bovet, A.; Shishkin, V.

    2010-01-01

    The 'dry' techniques of producing and clearing of some metals fluorides, their mixtures and cakes of a given composition obtained without usage gaseous HF for experiments under the Project ISTC No. 3749 are developed. The products of synthesizing and purification of oxygen-containing compounds, are studied by methods X-ray diffraction analysis, gravimetry or IR spectrometry. The experimental studies confirmed that solid NH 4 HF 2 can be efficiently used instead of an unsafe and corrosive HF gas for removal of oxygen-containing impurities from metal fluorides and for conversion of uranium and thorium dioxides to anhydrous tetra-fluorides. These processes do not require expensive equipment and special measures of safety. The electrochemical behavior of UF 4 solutions in a melt 77 LiF-23ThF 4 (mole%) was studied by cyclic voltammetry. Formal analysis of the obtained dependencies showed that in our experimental conditions the recharge U(IV) to U(III) is qualitatively consistent with voltammetric criteria and can be classified as reversible. However, the results of mathematical processing of voltammograms show that the basic calculated characteristics of this reaction differ from the theoretical values corresponding one-electron process controlled by the diffusion rate. This indicates quasi-reversibility of the studied reaction. (authors)

  16. Apparatus to measure vapor pressure, differential vapor pressure, liquid molar volume, and compressibility of liquids and solutions to the critical point. Vapor pressures, molar volumes, and compressibilities of protiobenzene and deuteriobenzene at elevated temperatures

    International Nuclear Information System (INIS)

    Kooner, Z.S.; Van Hook, W.A.

    1986-01-01

    An apparatus designed to measure vapor pressure differences between two similar liquids, such as isotopic isomers, or between a solution and its reference solvent at temperatures and pressures extending to the critical point is described. Vapor-phase volume is minimized and pressure is transmitted to the transducer through the liquid, thereby avoiding several experimental difficulties. Liquid can be injected into the heated part of the system by volumetrically calibrated screw injectors, thus permitting measurements of liquid molar volume, compressibility, and expansivity. The addition of a high-pressure circulating pump and injection valve allows the apparatus to be employed as a continuous dilution differential vapor pressure apparatus for determining partial molar free energies of solution. In the second part of the paper data on the vapor pressure, molar volume, compressibility, and expansivity and their isotope effects for C 6 H 6 and C 6 D 6 from room temperature to near the critical temperature are reported

  17. Recycling Cellulase from Enzymatic Hydrolyzate of Laser-Pretreated Corn Stover by UF Membrane

    Directory of Open Access Journals (Sweden)

    Shuang-Qi Tian

    2015-09-01

    Full Text Available The ultrafiltration membrane reactor, utilizing a membrane module with a suitable molecular weight alleyway, retains the larger cellulase components. Smaller molecules, such as the fermentable reducing sugars and water, pass through the membrane. The purpose of this work was to investigate the capability of recycling cellulase in the UF membrane. PS30 hollow fiber membrane, an ultrafiltration method using internal pressure, was found to be an ideal membrane separation device, allowing re-use of the enzyme. A Box-Behnken experimental design (BBD established the following optimum pretreatment parameters: operation pressure at 1.73 bar, temperature at 36.38 °C, and a pH of 5.92. Under these conditions, the model predicted a membrane flux yield of 2.3174 L/(m2•h. The rejection rate of the UF membrane was over 95%.

  18. High-temperature vaporization of thorium-uranium mixed monocarbide (Th1-y, Uy)C

    International Nuclear Information System (INIS)

    Koyama, Tadafumi; Yamawaki, Michio

    1989-01-01

    Vaporization thermodynamics of thorium-uranium mixed monocarbide phase (Th 1-y , U y )C was studied by mass spectrometric Knudsen effusion method for the compositions of (Th 0.9 , U 0.1 )C 0.855 , (Th 0.8 , U 0.2 )C 0.973 and (Th 0.6 , U 0.4 )C 0.973 . The partial vapor pressures of Th(g) and U(g) and activities of Th and U of these mixed monocarbides were determined at temperatures ranging from about 2000 to 2200 K. Further, the partial pressures of Th(g) and U(g) and activities of Th and U of the stoichiometric mixed monocarbides (Th 1-y , U y )C 1.00 were evaluated by compensating for the effect of carbon content. The Gibbs energies of formation of stoichiometric (Th 1-y , U y )C 1.00 were also evaluated. (orig.)

  19. New regulatory aspects of UF6 transport

    International Nuclear Information System (INIS)

    Biaggio, A.L.; Lee Gonzales, H.M.; Lopez Vietri, J.R.; Novo, R.G.

    1987-01-01

    In nuclear industry, a great amount of uranium is transformed from a chemical form to another. When the fuel cycle requires enrichment, uranium hexafluoride (UF 6) is handled, stored and transported in great quantities. To analyze the risks involved in possible accidents associated with UF 6 , radiological and chemical aspects must be considered. So far, the international practice was based on the adoption of regulations from a particular country (ANSI No. 14.1-1982.U.S.A.). In this way, the adoption of these norms at international level is difficult. For that reason, the International Atomic Energy Agency has attempted to consider the chemical risks associated with UF 6 in order to establish a more universal basis ('Recommendations for Providing Protection during the Transport of Uranium Hexafluoride' IAEA-TECDOC-423, Vienna, June 1987 - Austria). A critical analysis of these recommendations is presented in this work. The coherence and the degree of completion of the new recommendations are evaluated and the safety level is compared with that of the accepted regulations for toxic or corrosive substances and for radioactive materials transport. (Author)

  20. Dynamic Leidenfrost temperature on micro-textured surfaces: Acoustic wave absorption into thin vapor layer

    Science.gov (United States)

    Jerng, Dong Wook; Kim, Dong Eok

    2018-01-01

    The dynamic Leidenfrost phenomenon is governed by three types of pressure potentials induced via vapor hydrodynamics, liquid dynamic pressure, and the water hammer effect resulting from the generation of acoustic waves at the liquid-vapor interface. The prediction of the Leidenfrost temperature for a dynamic droplet needs quantitative evaluation and definition for each of the pressure fields. In particular, the textures on a heated surface can significantly affect the vapor hydrodynamics and the water hammer pressure. We present a quantitative model for evaluating the water hammer pressure on micro-textured surfaces taking into account the absorption of acoustic waves into the thin vapor layer. The model demonstrates that the strength of the acoustic flow into the liquid droplet, which directly contributes to the water hammer pressure, depends on the magnitude of the acoustic resistance (impedance) in the droplet and the vapor region. In consequence, the micro-textures of the surface and the increased spacing between them reduce the water hammer coefficient ( kh ) defined as the ratio of the acoustic flow into the droplet to total generated flow. Aided by numerical calculations that solve the laminar Navier-Stokes equation for the vapor flow, we also predict the dynamic Leidenfrost temperature on a micro-textured surface with reliable accuracy consistent with the experimental data.

  1. Vapor pressures and vaporization enthalpy of codlemone by correlation gas chromatography

    International Nuclear Information System (INIS)

    Schultz, Shannon M.; Harris, Harold H.; Chickos, James S.

    2015-01-01

    Highlights: • The vaporization enthalpy of codlemone has been evaluated. • The vapor pressure of codlemone has been evaluated from T = (298.15 to T b ) K. • Vapor pressures for the 1-alkanols standards are available from T = (298.15 to 500) K. - Abstract: The vapor pressure and vaporization enthalpy of codlemone (trans, trans 8,10-dodecadien-1-ol), the female sex hormone of the codling moth is evaluated by correlation gas chromatography using a series of saturated primary alcohols as standards. A vaporization enthalpy of (92.3 ± 2.6) kJ · mol −1 and a vapor pressure, p/Pa = (0.083 ± 0.012) were evaluated at T = 298.15 K. An equation for the evaluation of vapor pressure from ambient temperature to boiling has been derived by correlation for codlemone. The calculated boiling temperature of T B = 389 K at p = 267 Pa is within the temperature range reported in the literature. A normal boiling temperature of T B = (549.1 ± 0.1) K is also estimated by extrapolation

  2. Atmospheric pressure chemical vapor deposition (APCVD) grown bi-layer graphene transistor characteristics at high temperature

    KAUST Repository

    Qaisi, Ramy M.; Smith, Casey; Hussain, Muhammad Mustafa

    2014-01-01

    We report the characteristics of atmospheric chemical vapor deposition grown bilayer graphene transistors fabricated on ultra-scaled (10 nm) high-κ dielectric aluminum oxide (Al2O3) at elevated temperatures. We observed that the drive current increased by >400% as temperature increased from room temperature to 250 °C. Low gate leakage was maintained for prolonged exposure at 100 °C but increased significantly at temperatures >200 °C. These results provide important insights for considering chemical vapor deposition graphene on aluminum oxide for high temperature applications where low power and high frequency operation are required. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Atmospheric pressure chemical vapor deposition (APCVD) grown bi-layer graphene transistor characteristics at high temperature

    KAUST Repository

    Qaisi, Ramy M.

    2014-05-15

    We report the characteristics of atmospheric chemical vapor deposition grown bilayer graphene transistors fabricated on ultra-scaled (10 nm) high-κ dielectric aluminum oxide (Al2O3) at elevated temperatures. We observed that the drive current increased by >400% as temperature increased from room temperature to 250 °C. Low gate leakage was maintained for prolonged exposure at 100 °C but increased significantly at temperatures >200 °C. These results provide important insights for considering chemical vapor deposition graphene on aluminum oxide for high temperature applications where low power and high frequency operation are required. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Nonlinear response of tropical lower-stratospheric temperature and water vapor to ENSO

    Directory of Open Access Journals (Sweden)

    C. I. Garfinkel

    2018-04-01

    Full Text Available A series of simulations using the NASA Goddard Earth Observing System Chemistry–Climate Model are analyzed in order to aid in the interpretation of observed interannual and sub-decadal variability in the tropical lower stratosphere over the past 35 years. The impact of El Niño–Southern Oscillation on temperature and water vapor in this region is nonlinear in boreal spring. While moderate El Niño events lead to cooling in this region, strong El Niño events lead to warming, even as the response of the large-scale Brewer–Dobson circulation appears to scale nearly linearly with El Niño. This nonlinearity is shown to arise from the response in the Indo-West Pacific to El Niño: strong El Niño events lead to tropospheric warming extending into the tropical tropopause layer and up to the cold point in this region, where it allows for more water vapor to enter the stratosphere. The net effect is that both strong La Niña and strong El Niño events lead to enhanced entry water vapor and stratospheric moistening in boreal spring and early summer. These results lead to the following interpretation of the contribution of sea surface temperatures to the decline in water vapor in the early 2000s: the very strong El Niño event in 1997/1998, followed by more than 2 consecutive years of La Niña, led to enhanced lower-stratospheric water vapor. As this period ended in early 2001, entry water vapor concentrations declined. This effect accounts for approximately one-quarter of the observed drop.

  5. Nonlinear response of tropical lower-stratospheric temperature and water vapor to ENSO

    Science.gov (United States)

    Garfinkel, Chaim I.; Gordon, Amit; Oman, Luke D.; Li, Feng; Davis, Sean; Pawson, Steven

    2018-04-01

    A series of simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model are analyzed in order to aid in the interpretation of observed interannual and sub-decadal variability in the tropical lower stratosphere over the past 35 years. The impact of El Niño-Southern Oscillation on temperature and water vapor in this region is nonlinear in boreal spring. While moderate El Niño events lead to cooling in this region, strong El Niño events lead to warming, even as the response of the large-scale Brewer-Dobson circulation appears to scale nearly linearly with El Niño. This nonlinearity is shown to arise from the response in the Indo-West Pacific to El Niño: strong El Niño events lead to tropospheric warming extending into the tropical tropopause layer and up to the cold point in this region, where it allows for more water vapor to enter the stratosphere. The net effect is that both strong La Niña and strong El Niño events lead to enhanced entry water vapor and stratospheric moistening in boreal spring and early summer. These results lead to the following interpretation of the contribution of sea surface temperatures to the decline in water vapor in the early 2000s: the very strong El Niño event in 1997/1998, followed by more than 2 consecutive years of La Niña, led to enhanced lower-stratospheric water vapor. As this period ended in early 2001, entry water vapor concentrations declined. This effect accounts for approximately one-quarter of the observed drop.

  6. Growth behavior of LiMn2O4 particles formed by solid-state reactions in air and water vapor

    International Nuclear Information System (INIS)

    Kozawa, Takahiro; Yanagisawa, Kazumichi; Murakami, Takeshi; Naito, Makio

    2016-01-01

    Morphology control of particles formed during conventional solid-state reactions without any additives is a challenging task. Here, we propose a new strategy to control the morphology of LiMn 2 O 4 particles based on water vapor-induced growth of particles during solid-state reactions. We have investigated the synthesis and microstructural evolution of LiMn 2 O 4 particles in air and water vapor atmospheres as model reactions; LiMn 2 O 4 is used as a low-cost cathode material for lithium-ion batteries. By using spherical MnCO 3 precursor impregnated with LiOH, LiMn 2 O 4 spheres with a hollow structure were obtained in air, while angulated particles with micrometer sizes were formed in water vapor. The pore structure of the particles synthesized in water vapor was found to be affected at temperatures below 700 °C. We also show that the solid-state reaction in water vapor is a simple and valuable method for the large-scale production of particles, where the shape, size, and microstructure can be controlled. - Graphical abstract: This study has demonstrated a new strategy towards achieving morphology control without the use of additives during conventional solid-state reactions by exploiting water vapor-induced particle growth. - Highlights: • A new strategy to control the morphology of LiMn 2 O 4 particles is proposed. • Water vapor-induced particle growth is exploited in solid-state reactions. • The microstructural evolution of LiMn 2 O 4 particles is investigated. • The shape, size and microstructure can be controlled by solid-state reactions.

  7. Spectroscopic properties of K5Li2UF10

    International Nuclear Information System (INIS)

    Karbowiak, M.; Gajek, Z.; Drozdzynski, J.

    2005-01-01

    A new uranium (III) fluoro-complex of the formula K 5 Li 2 UF 10 has been synthesised and characterised by X-ray powder diffraction and electronic absorption spectra measurements. The compound crystallises in the orthorhombic system, space group Pnma, with a = 20.723, b = 7.809, c = 6.932 A, V = 1121.89 A 3 , Z = 4 and is isostructural with its K 5 Li 2 NdF 10 and K 5 Li 2 LaF 10 analogous. The absorption spectrum of a polycrystalline sample of K 5 Li 2 UF 10 was recorded at 4.2 K in the 3500-45,000 cm -1 range and is discussed. The observed crystal-field levels were assigned and fitted to parameters of the simplified angular overlap model (AOM) and next to those of a semi-empirical Hamiltonian, which was representing the combined atomic and one-electron crystal-field interactions. The starting values of the AOM parameters were obtained from ab initio calculations. The analysis of the spectra enabled the assignment of 71 crystal-field levels of U 3+ with a relatively small r.m.s. deviation of 37 cm -1 . The total splitting of 714 cm -1 was calculated for the 4 I 9/2 ground multiplet

  8. Spectroscopic properties of K 5Li 2UF 10

    Science.gov (United States)

    Karbowiak, M.; Gajek, Z.; Drożdżyński, J.

    2005-04-01

    A new uranium (III) fluoro-complex of the formula K 5Li 2UF 10 has been synthesised and characterised by X-ray powder diffraction and electronic absorption spectra measurements. The compound crystallises in the orthorhombic system, space group Pnma, with a = 20.723, b = 7.809, c = 6.932 Å, V = 1121.89 Å 3, Z = 4 and is isostructural with its K 5Li 2NdF 10 and K 5Li 2LaF 10 analogous. The absorption spectrum of a polycrystalline sample of K 5Li 2UF 10 was recorded at 4.2 K in the 3500-45,000 cm -1 range and is discussed. The observed crystal-field levels were assigned and fitted to parameters of the simplified angular overlap model (AOM) and next to those of a semi-empirical Hamiltonian, which was representing the combined atomic and one-electron crystal-field interactions. The starting values of the AOM parameters were obtained from ab initio calculations. The analysis of the spectra enabled the assignment of 71 crystal-field levels of U 3+ with a relatively small r.m.s. deviation of 37 cm -1. The total splitting of 714 cm -1 was calculated for the 4I 9/2 ground multiplet.

  9. The regulations and the problems of their implementation in UF6 transport

    International Nuclear Information System (INIS)

    Devillers, C.; Grenier, M.; Ringot, C.; Warniez, P.

    1988-12-01

    UF 6 is currently transported in packagings which were developed in the sixties - standardized and used all over the world, these packagings perform their duty adequately. Nevertheless, the growing amounts of UF 6 and the changes in the regulations now raises the problem of compliance of these packagings with the latter. The problems which deserve special attention are: selection of the packaging type in terms of the origin and the enrichment, design of valve covers, behaviour at low temperatures, regulatory requirements in handling, tying down cleaning and unloading, allowable dose rate increase in case of minor mishaps, behaviour in fire, taking into account the toxicity, identification of special features required in the case of controlled moderation of fissile packages, transport conditions of empty packagings containing heels. In this paper are reviewed the results of this analysis, which is limited to the case of transport using cylinders of 48Y and 30B

  10. The vapor pressure and vaporization enthalpy of R-(+)-menthofuran, a hepatotoxin metabolically derived from the abortifacient terpene, (R)-(+)-pulegone by correlation gas chromatography

    International Nuclear Information System (INIS)

    Gobble, Chase; Chickos, James S.

    2016-01-01

    Highlights: • The vaporization enthalpy and vapor pressure of R-(+) menthofuran is evaluated. • The normal boiling temperature is predicted and compared to experimental and predicted values. • A vapor pressure equation as a function of temperature for menthofuran is evaluated. - Abstract: The vapor pressure as a function of temperature and its vaporization enthalpy at T = 298.15 K of R-(+)-menthofuran, a substance metabolically derived from R-(+)-pulegone that is both a flavoring agent at low concentrations and a hepatotoxin at larger ones, is evaluated by correlation-gas chromatography. A vapor pressure p/Pa = (36 ± 12) has been evaluated at T = 298.15 K, and a normal boiling temperature of T_b/K = 482.4 K is predicted. A boiling temperature of T_b/K = 374.3 compares with the literature value of T_b/K = 371.2 at reduced pressure, p/kPa = 2.93. The vaporization enthalpy of (56.5 ± 3.0) kJ·mol"−"1 compares to an estimated value of (57.8 ± 2.9) kJ·mol"−"1.

  11. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    Science.gov (United States)

    Nicovich, J. M.; Wine, P. H.

    1988-01-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  12. Vapor pressure and enthalpy of vaporization of oil of catnip by correlation gas chromatography

    International Nuclear Information System (INIS)

    Simmons, Daniel; Gobble, Chase; Chickos, James

    2016-01-01

    Highlights: • Vaporization enthalpies of the nepetalactones from oil of catnip have been evaluated. • Vapor pressures from T = (298.15 to 350) K have been evaluated. • Oil of catnip has a vapor pressure similar to DEET at T = 298.15 K. - Abstract: The vaporization enthalpy and vapor pressure of the two nepetalactones found in Nepeta cataria have been evaluated by correlation gas chromatography. Vaporization enthalpies at T = 298.15 K of {(68.0 ± 1.9) and (69.4 ± 1.9)} kJ ⋅ mol"−"1 have been derived for the minor diastereomer, (4aS,7S,7aS)-nepetalactone, and major one, (4aS,7S,7aR)-nepetalactone, respectively. Vapor pressures also at T = 298.15 K of p = (1.2 ± 0.04) Pa and (0.91 ± 0.03) Pa have been evaluated for the minor and the major stereoisomer. In addition to being of interest because of the remarkable effect it has on various felids, oil of catnip is also quite effective in repelling mosquitoes, comparable to diethyl-m-toluamide (DEET). The vapor pressures evaluated in this work suggest that the two stereoisomers have similar volatility to DEET at ambient temperatures.

  13. Assessment of Fluctuation Patterns Similarity in Temperature and Vapor Pressure Using Discrete Wavelet Transform

    Directory of Open Access Journals (Sweden)

    A. Araghi

    2014-12-01

    Full Text Available Period and trend are two main effective and important factors in hydro-climatological time series and because of this importance, different methods have been introduced and applied to study of them, until now. Most of these methods are statistical basis and they are classified in the non-parametric tests. Wavelet transform is a mathematical based powerful method which has been widely used in signal processing and time series analysis in recent years. In this research, trend and main periodic patterns similarity in temperature and vapor pressure has been studied in Babolsar, Tehran and Shahroud synoptic stations during 55 years period (from 1956 to 2010, using wavelet method and the sequential Mann-Kendall trend test. The results show that long term fluctuation patterns in temperature and vapor pressure have more correlations in the arid and semi-arid climates, as well as short term oscillation patterns in temperature and vapor pressure in the humid climates, and these dominant periods increase with the aridity of region.

  14. Vapor Pressure Measurements of LiBH4, NaBH 4 and Ca(BH4)2 using Knudsen Torsion Effusion Gravimetric Method

    Science.gov (United States)

    Danyan, Mohammad Masoumi

    Hydrogen storage is one of the critical technologies needed on the path towards commercialization for mobile applications. In the past few years, a range of new light weight hydrogen containing material has been discovered with good storage properties. Among them, lithium borohydride (LiBH 4) sodium borohydride (NaBH4) and calcium borohydride (Ca(BH 4)2) have shown promising results to be used as solid state hydrogen storage material. In this work, we have determined equilibrium vapor pressures of LiBH 4 NaBH4 and Ca(BH4)2 obtained by Torsion effusion thermogravimetric method. Results for all the three hydrides exhibited that a small fraction of the materials showed congruency, and sublimed as gaseous compound, but the majority of the material showed incongruent vaporization. Two Knudsen cells of 0.3 and 0.6mm orifice size was employed to measure the total vapor pressures. A Whitman-Motzfeldt method is used to extrapolate the measured vapor pressures to zero orifice size to calculate the equilibrium vapor pressures. In the case of LiBH4 we found that 2% of the material evaporated congruently (LiBH4(s) → LiBH4(g)) according to the equation: logPLiBH4/P 0 =-3263.5 +/-309/T + (1.079 +/-0.69) and rest as incongruent vaporization to LiH, B, and hydrogen gas according to the equation logPeq/P0 =(-3263.5 +/-309)/T+ (2.458 +/-0.69) with DeltaH evap.= 62.47+/-5.9 kJ/mol of H2, DeltaSevap. = 47.05+/-13 J/mol of H2.K. The NaBH4 also had somewhat similar behavior, with 9% congruent evaporation and equilibrium vapor pressure equation of logPLiBH4=-7700+/-335/ T+ (6.7+/-1.5) and 91% incongruent decomposition to Na and Boron metal, and hydrogen gas. The enthalpy of vaporization; DeltaHevap. = 147.2+/-6.4kJ/molH2 and DeltaSevap.= 142 +/-28 kJ/molH2.K (550-650K). The Ca(BH4) 2 exhibited similar vaporization behavior with congruency of 3.2%. The decomposition products are CaH2 and Boron metal with evolution of hydrogen gas varying with the pressure equation as logPeq /P0 =(-1562

  15. Estimated vapor pressure for WTP process streams

    Energy Technology Data Exchange (ETDEWEB)

    Pike, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Poirier, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-01-01

    Design assumptions during the vacuum refill phase of the Pulsed Jet Mixers (PJMs) in the Hanford Waste Treatment and Immobilization Plant (WTP) equate the vapor pressure of all process streams to that of water when calculating the temperature at which the vacuum refill is reduced or eliminated. WTP design authority asked the authors to assess this assumption by performing calculations on proposed feed slurries to calculate the vapor pressure as a function of temperature. The vapor pressure was estimated for each WTP waste group. The vapor pressure suppression caused by dissolved solids is much greater than the increase caused by organic components such that the vapor pressure for all of the waste group compositions is less than that of pure water. The vapor pressure for each group at 145°F ranges from 81% to 98% of the vapor pressure of water. If desired, the PJM could be operated at higher temperatures for waste groups with high dissolved solids that suppress vapor pressure. The SO4 group with the highest vapor pressure suppression could be operated up to 153°F before reaching the same vapor pressure of water at 145°F. However, most groups would reach equivalent vapor pressure at 147 to 148°F. If any of these waste streams are diluted, the vapor pressure can exceed the vapor pressure of water at mass dilution ratios greater than 10, but the overall effect is less than 0.5%.

  16. Regulation of Silk Material Structure by Temperature-Controlled Water Vapor Annealing

    Science.gov (United States)

    Hu, Xiao; Shmelev, Karen; Sun, Lin; Gil, Eun-Seok; Park, Sang-Hyug; Cebe, Peggy; Kaplan, David L.

    2011-01-01

    We present a simple and effective method to obtain refined control of the molecular structure of silk biomaterials through physical temperature-controlled water vapor annealing (TCWVA). The silk materials can be prepared with control of crystallinity, from a low content using conditions at 4°C (alpha-helix dominated silk I structure), to highest content of ~60% crystallinity at 100°C (beta-sheet dominated silk II structure). This new physical approach covers the range of structures previously reported to govern crystallization during the fabrication of silk materials, yet offers a simpler, green chemistry, approach with tight control of reproducibility. The transition kinetics, thermal, mechanical, and biodegradation properties of the silk films prepared at different temperatures were investigated and compared by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), uniaxial tensile studies, and enzymatic degradation studies. The results revealed that this new physical processing method accurately controls structure, in turn providing control of mechanical properties, thermal stability, enzyme degradation rate, and human mesenchymal stem cell interactions. The mechanistic basis for the control is through the temperature controlled regulation of water vapor, to control crystallization. Control of silk structure via TCWVA represents a significant improvement in the fabrication of silk-based biomaterials, where control of structure-property relationships is key to regulating material properties. This new approach to control crystallization also provides an entirely new green approach, avoiding common methods which use organic solvents (methanol, ethanol) or organic acids. The method described here for silk proteins would also be universal for many other structural proteins (and likely other biopolymers), where water controls chain interactions related to material properties. PMID:21425769

  17. Preliminary Hazard Analysis applied to Uranium Hexafluoride - UF6 production plant

    International Nuclear Information System (INIS)

    Tomzhinsky, David; Bichmacher, Ricardo; Braganca Junior, Alvaro; Peixoto, Orpet Jose

    1996-01-01

    The purpose of this paper is to present the results of the Preliminary hazard Analysis applied to the UF 6 Production Process, which is part of the UF 6 Conversion Plant. The Conversion Plant has designed to produce a high purified UF 6 in accordance with the nuclear grade standards. This Preliminary Hazard Analysis is the first step in the Risk Management Studies, which are under current development. The analysis evaluated the impact originated from the production process in the plant operators, members of public, equipment, systems and installations as well as the environment. (author)

  18. The electron spectrum of UF6 recorded in the gas phase

    Science.gov (United States)

    Mârtensson, N.; Malmquist, P.-Å.; Svensson, S.; Johansson, B.

    1984-06-01

    Gas phase core and valence electron spectra from UF6, excited by AlKα monochromatized x rays, in the binding energy range 0-1000 eV are presented. It is shown that the AlKα excited valence electron spectrum can be used to reassign the highest occupied molecular orbital (HOMO) in UF6. Many-body effects on the core levels are discussed and core level lifetimes are determined. The shift between solid phase and gas phase electron binding energies for core lines is used to discuss the U5 f population in UF6.

  19. Vapor Measurement System of Essential Oil Based on MOS Gas Sensors Driven with Advanced Temperature Modulation Technique

    Science.gov (United States)

    Sudarmaji, A.; Margiwiyatno, A.; Ediati, R.; Mustofa, A.

    2018-05-01

    The aroma/vapor of essential oils is complex compound which depends on the content of the gases and volatiles generated from essential oil. This paper describes a design of quick, simple, and low-cost static measurement system to acquire vapor profile of essential oil. The gases and volatiles are captured in a chamber by means of 9 MOS gas sensors which driven with advance temperature modulation technique. A PSoC CY8C28445-24PVXI based-interface unit is built to generate the modulation signal and acquire all sensor output into computer wirelessly via radio frequency serial communication using Digi International Inc., XBee (IEEE 802.15.4) through developed software under Visual.Net. The system was tested to measure 2 kinds of essential oil (Patchouli and Clove Oils) in 4 temperature modulations (without, 0.25 Hz, 1 Hz, and 4 Hz). A cycle measurement consists of reference and sample measurement sequentially which is set during 2 minutes in every 1 second respectively. It is found that the suitable modulation is 0,25Hz; 75%, and the results of Principle Component Analysis show that the system is able to distinguish clearly between Patchouli Oil and Clove Oil.

  20. UF{sub 6} cylinder inspections at PGDP

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, G.W.; Whinnery, W.N. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Routine inspections of all UF{sub 6} cylinders at the Paducah Gaseous Diffusion Plant have been mandated by the Department of Energy. A specific UF{sub 6} cylinder inspection procedure for what items to inspect and training for the operators prior to inspection duty are described. The layout of the cylinder yards and the forms used in the inspections are shown. The large number of cylinders (>30,000) to inspect and the schedule for completion on the mandated time table are discussed. Results of the inspections and the actions to correct the deficiencies are explained. Future inspections and movement of cylinders for relocation of certain cylinder yards are defined.

  1. Application of Chlorine-Assisted Chemical Vapor Deposition of Diamond at Low Temperatures

    Science.gov (United States)

    Pan, Chenyu; Altemir, David A.; Margrave, John L.; Hauge, Robert H.

    1994-01-01

    Low temperature deposition of diamond has been achieved by a chlorine-assisted diamond chemical vapor deposition (CA-CVD) process. This method begins with the thermal dissociation of molecular chlorine into atomic chlorine in a resistively heated graphite furnace at temperatures between 1300 and 1500 deg. C. The atomic chlorine, upon mixing, subsequently reacts with molecular hydrogen and hydrocarbons. The rapid exchange reactions between the atomic chlorine, molecular hydrogen, and hydrocarbons give rise to the atomic hydrogen and carbon precursors required for diamond deposition. Homoepitaxial diamond growth on diamond substrates has been studied over the substrate temperature range of 100-950 C. It was found that the diamond growth rates are approximately 0.2 microns/hr in the temperature range between 102 and 300 C and that the growth rates do not decrease significantly with a decrease in substrate temperature. This is unique because the traditional diamond deposition using H2/CH4 systems usually disappears at substrate temperatures below approx. 500 deg. C. This opens up a possible route to the deposition of diamond on low-melting point materials such as aluminum and its alloys.

  2. Gas-phase UF6 enrichment monitor for enrichment plant safeguards

    International Nuclear Information System (INIS)

    Strittmatter, R.B.; Tape, J.W.

    1980-03-01

    An in-line enrichment monitor is being developed to provide real-time enrichment data for the gas-phase UF 6 feed stream of an enrichment plant. The nondestructive gamma-ray assay method can be used to determine the enrichment of natural UF 6 with a relative precision of better than 1% for a wide range of pressures

  3. Natural phenomena evaluations of the K-25 site UF6 cylinder storage yards

    International Nuclear Information System (INIS)

    Fricke, K.E.

    1996-01-01

    The K-25 Site UF 6 cylinder storage yards are used for the temporary storage of UF 6 normal assay cylinders and long-term storage of other UF 6 cylinders. The K-25 Site UF 6 cylinder storage yards consist of six on-site areas: K-1066-B, K-1066-E, K-1066-F, K-1066-J, K-1066-K and K-1066-L. There are no permanent structures erected on the cylinder yards, except for five portable buildings. The operating contractor for the K-25 Site is preparing a Safety Analysis Report (SAR) to examine the safety related aspects of the K-25 Site UF 6 cylinder storage yards. The SAR preparation encompasses many tasks terminating in consequence analysis for the release of gaseous and liquid UF 6 , one of which is the evaluation of natural phenomena threats, such as earthquakes, floods, and winds. In support of the SAR, the six active cylinder storage yards were evaluated for vulnerabilities to natural phenomena, earthquakes, high winds and tornados, tornado-generated missiles, floods (local and regional), and lightning. This report summarizes those studies. 30 refs

  4. Aerosol material release rates from zircaloy-4 at temperatures from 2000 to 22000C

    International Nuclear Information System (INIS)

    Mulpuru, S.R.; Wren, D.J.; Rondeau, R.K.

    1987-01-01

    During some postulated severe accidents involving loss of coolant and loss of emergency coolant injection, the temperatures in a CANDU reactor fuel channel become high enough to cause failure and melting of the Zircaloy fuel cladding. At such high temperatures, vapors of fission products and structural (fuel and cladding) materials will be released into the coolant steam and hydrogen mixture. These vapors will condense as cooler conditions are encountered downstream. The vapors from structural materials are relatively involatile; therefore, they will condense readily into aerosol particles. These particles, in turn, will provide sites for the condensation of the more volatile fission products. The aerosol transport of fission products in the primary heat transport system (PHTS) will thus be influenced by the structural material release rates. As part of an ongoing program to develop predictive tools for aerosol and associated fission product transport through the PHTS, experiments have been conducted to measure the vapor mass release rates of the alloying elements from Zircaloy-4 at high temperatures. The paper presents the results and analysis of these experiments

  5. HGSYSTEMUF6, Simulating Dispersion Due to Atmospheric Release of Uranium Hexafluoride (UF6)

    International Nuclear Information System (INIS)

    Hanna, G; Chang, J.C.; Zhang, J.X.; Bloom, S.G.; Goode, W.D. Jr; Lombardi, D.A.; Yambert, M.W.

    2001-01-01

    1 - Description of program or function: HGSYSTEMUF6 is a suite of models designed for use in estimating consequences associated with accidental, atmospheric release of Uranium Hexafluoride (UF 6 ) and its reaction products, namely Hydrogen Fluoride (HF), and other non-reactive contaminants which are either negatively, neutrally, or positively buoyant. It is based on HGSYSTEM Version 3.0 of Shell Research LTD., and contains specific algorithms for the treatment of UF 6 chemistry and thermodynamics. HGSYSTEMUF6 contains algorithms for the treatment of dense gases, dry and wet deposition, effects due to the presence of buildings (canyon and wake), plume lift-off, and the effects of complex terrain. The models components of the suite include (1) AEROPLUME/RK, used to model near-field dispersion from pressurized two-phase jet releases of UF6 and its reaction products, (2) HEGADAS/UF6 for simulating dense, ground based release of UF 6 , (3) PGPLUME for simulation of passive, neutrally buoyant plumes (4) UF6Mixer for modeling warm, potentially reactive, ground-level releases of UF 6 from buildings, and (5) WAKE, used to model elevated and ground-level releases into building wake cavities of non-reactive plumes that are either neutrally or positively buoyant. 2 - Methods: The atmospheric release and transport of UF 6 is a complicated process involving the interaction between dispersion, chemical and thermodynamic processes. This process is characterized by four separate stages (flash, sublimation, chemical reaction entrainment and passive dispersion) in which one or more of these processes dominate. The various models contained in the suite are applicable to one or more of these stages. For example, for modeling reactive, multiphase releases of UF 6 , the AEROPLUME/RK component employs a process-splitting scheme which numerically integrates the differential equations governing dispersion, UF 6 chemistry, and thermodynamics. This algorithm is based on the assumption that

  6. Emission characteristics of uranium hexafluoride at high temperatures

    International Nuclear Information System (INIS)

    Krascella, N.L.

    1976-01-01

    An experimental study was conducted to ascertain the spectral characteristics of uranium hexafluoride (UF 6 ) and possible UF 6 thermal decomposition products as a function of temperature and pressure. Relative emission measurements were made for UF 6 /Argon mixtures heated in a plasma torch over a range of temperatures from 800 to about 3600 0 K over a wavelength range from 80 to 600 nm. Total pressures were varied from 1 to approximately 1.7 atm. Similarly absorption measurements were carried out in the visible region from 420 to 580 nm over a temperature range from about 1000 to 1800 0 K. Total pressure for these measurements was 1.0 atm

  7. Zno Micro/Nanostructures Grown on Sapphire Substrates Using Low-Temperature Vapor-Trapped Thermal Chemical Vapor Deposition: Structural and Optical Properties

    Directory of Open Access Journals (Sweden)

    Po-Sheng Hu

    2017-12-01

    Full Text Available In this research, the Zn(C5H7O22·xH2O-based growth of ZnO micro/nanostructures in a low temperature, vapor-trapped chemical vapor deposition system was attempted to optimize structural and optical properties for potential biomedical applications. By trapping in-flow gas molecules and Zinc vapor inside a chamber tube by partially obstructing a chamber outlet, a high pressure condition can be achieved, and this experimental setup has the advantages of ease of synthesis, being a low temperature process, and cost effectiveness. Empirically, the growth process proceeded under a chamber condition of an atmospheric pressure of 730 torr, a controlled volume flow rate of input gas, N2/O2, of 500/500 Standard Cubic Centimeters per Minute (SCCM, and a designated oven temperature of 500 °C. Specifically, the dependence of structural and optical properties of the structures on growth duration and spatially dependent temperature were investigated utilizing scanning electron microscopy, X-ray diffraction (XRD, photoluminescence (PL, and ultraviolet-visible transmission spectroscopy. The experimental results indicate that the grown thin film observed with hexagonal structures and higher structural uniformity enables more prominent structural and optical signatures. XRD spectra present the dominant peaks along crystal planes of (002 and (101 as the main direction of crystallization. In addition, while the structures excited with laser wavelength of 325 nm emit a signature radiation around 380 nm, an ultraviolet lamp with a wavelength of 254 nm revealed distinctive photoluminescence peaks at 363.96 nm and 403.52 nm, elucidating different degrees of structural correlation as functions of growth duration and the spatial gradient of temperature. Transmittance spectra of the structures illustrate typical variation in the wavelength range of 200 nm to 400 nm, and its structural correlation is less significant when compared with PL.

  8. Long-term trends in stratospheric ozone, temperature, and water vapor over the Indian region

    Science.gov (United States)

    Thankamani Akhil Raj, Sivan; Venkat Ratnam, Madineni; Narayana Rao, Daggumati; Venkata Krishna Murthy, Boddam

    2018-01-01

    We have investigated the long-term trends in and variabilities of stratospheric ozone, water vapor and temperature over the Indian monsoon region using the long-term data constructed from multi-satellite (Upper Atmosphere Research Satellite (UARS MLS and HALOE, 1993-2005), Aura Microwave Limb Sounder (MLS, 2004-2015), Sounding of the Atmosphere using Broadband Emission Radiometry (SABER, 2002-2015) on board TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics)) observations covering the period 1993-2015. We have selected two locations, namely, Trivandrum (8.4° N, 76.9° E) and New Delhi (28° N, 77° E), covering northern and southern parts of the Indian region. We also used observations from another station, Gadanki (13.5° N, 79.2° E), for comparison. A decreasing trend in ozone associated with NOx chemistry in the tropical middle stratosphere is found, and the trend turned to positive in the upper stratosphere. Temperature shows a cooling trend in the stratosphere, with a maximum around 37 km over Trivandrum (-1.71 ± 0.49 K decade-1) and New Delhi (-1.15 ± 0.55 K decade-1). The observed cooling trend in the stratosphere over Trivandrum and New Delhi is consistent with Gadanki lidar observations during 1998-2011. The water vapor shows a decreasing trend in the lower stratosphere and an increasing trend in the middle and upper stratosphere. A good correlation between N2O and O3 is found in the middle stratosphere (˜ 10 hPa) and poor correlation in the lower stratosphere. There is not much regional difference in the water vapor and temperature trends. However, upper stratospheric ozone trends over Trivandrum and New Delhi are different. The trend analysis carried out by varying the initial year has shown significant changes in the estimated trend.

  9. Epidemiologisk forskning om uførepensjon i Norden

    Directory of Open Access Journals (Sweden)

    Johan Håkon Bjørngaard

    2010-01-01

    Full Text Available En relativ stor andel av befolkningen i yrkesaktiv alder i de nordiske landene mottar uførepensjon, og i Norge er det en klar tendens til økning. Parallelt med dette har interessen for forskning rundt uførepensjon som fenomen økt. Vi har i denne studien beskrevet den epidemiologiske forskningen om uførepensjon i Norden. I en systematisk litteraturgjennomgang fant vi 118 aktuelle artikler. Alle de nordiske landene er godt representert. Kohortstudier med uførepensjon som endepunkt utgjorde hovedvekten av materialet, hvor 67 var populasjonsbaserte mens 29 tok utgangspunkt i selekterte pasientpopulasjoner. I alt seks kohortstudier benyttet uførepensjon som eksponering. Vi fant videre syv kasus-kontrollstudier og ni forsøk. Det er betydelig dokumentasjon på at ulike sykdommer og helseplager er assosiert med økt risiko for uførhet, i tillegg til at sosioøkonomiske og arbeidsrelaterte forhold er av betydning. Gjennomgangen viser at den epidemiologiske forskningen for det meste har rettet blikket mot individuelle årsaker til uførepensjonering. Selv om denne forskningen er viktig, kan den neppe forklare økningen vi har sett i det siste tiåret. Den videre forskningen bør utforske nærmere hvordan individuell sårbarhet ender i utstøtelse fra arbeidslivet. Med tanke på den omfattende forskningen om årsaker på dette feltet, bør man også i større grad gjennomføre forsøk for å bedre utsatte gruppers arbeidsdeltakelse.Bjørngaard JH, Krokstad S, Johnsen R, Karlsen AO, Pape K, Støver M, Sund E, Westin S. Epidemiological research on disability benefits in the Nordic countries. Nor J Epidemiol 2009; 19 (2: 103-114 ENGLISH SUMMARYA substantial part of the workforce in the Nordic countries receives a disability benefit, and in Norway this beneficiary rate is growing. As a result, disability benefit has been the subject of new interest and research. In this study we have reviewed the epidemiological research on disability benefit in the

  10. Vapor pressures and enthalpies of vaporization of azides

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Emel'yanenko, Vladimir N.; Algarra, Manuel; Manuel Lopez-Romero, J.; Aguiar, Fabio; Enrique Rodriguez-Borges, J.; Esteves da Silva, Joaquim C.G.

    2011-01-01

    Highlights: → We prepared and measured vapor pressures and vaporization enthalpies of 7 azides. → We examined consistency of new and available in the literature data. → Data for geminal azides and azido-alkanes selected for thermochemical calculations. - Abstract: Vapor pressures of some azides have been determined by the transpiration method. The molar enthalpies of vaporization Δ l g H m of these compounds were derived from the temperature dependencies of vapor pressures. The measured data sets were successfully checked for internal consistency by comparison with vaporization enthalpies of similarly structured compounds.

  11. Nucleation and droplet growth from supersaturated vapor at temperatures below the triple point temperature

    DEFF Research Database (Denmark)

    Toxværd, Søren

    2016-01-01

    temperature Ttr.p. crystallizes via a liquid droplet is an example of Ostwald's step rule. The homogeneous nucleation in the supersaturated gas is not to a crystal, but to a liquid-like critical nucleus. We have for the first time performed constant energy (NVE) Molecular Dynamics (MD) of homogeneous...... nucleation without the use of a thermostat. The simulations of homogeneous nucleation in a Lennard-Jones system from supersaturated vapor at temperatures below Ttr.p. reveals that the nucleation to a liquid-like critical nucleus is initiated by a small cold cluster [S. Toxvaerd, J. Chem. Phys. \\textbf{143...

  12. Properties of Sago Particleboards Resinated with UF and PF Resin

    Directory of Open Access Journals (Sweden)

    Chen Chiang Tay

    2016-01-01

    Full Text Available The sago processing industry in Mukah, Sarawak, had generated huge amount of sago waste after the milling process and scientists have employed the waste into composite material. In this work, sago residues were mixed with the Phenol Formaldehyde (PF and Urea Formaldehyde (UF for particleboard fabrication. The fabrication and testing methods are based on JIS A 5908 Standard. A single layer particleboard using sago particles was fabricated at targeted density of 600 kg/m3. Particles with weight fractions of 90%, 85%, and 80% with two different matrices were used in the fabrication. The results demonstrated that the samples with different weight fraction and matrix have great influence on the mechanical properties such as MOR, MOE, Young’s Modulus, tensile strength, impact strength, screw test, and internal bonding. The sago UF/PF particleboard only displays single stage decomposition. All the panels underwent physical tests which are water absorption and thickness swelling. The combination of sago particles with UF/PF can be utilized for general indoor application purposes such as furniture manufacturing. Sago particleboard made by UF/PF provided the advantages like optimized performance, minimized weight and volume, cost effectiveness, chemical resistance, and resistance to biodegradation.

  13. Évolution qualitative et quantitative des composantes de l'œuf ...

    African Journals Online (AJOL)

    SARAH

    28 févr. 2014 ... contrôle de coquille et de calibre dans les fermes. Mots clés : œuf, pondeuse, ... dynamique qualitative des composantes de l'œuf . Certains auteurs ont ... programme de conduite et de gestion d'élevage. Élevées en bande ...

  14. Transport of UF6 in compliance with TS-R-1

    International Nuclear Information System (INIS)

    Dekker, B.G.

    2004-01-01

    The IAEA Regulations TS-R-1 (ST-1, Revised) 1996 Edition include requirements for packages containing uranium hexafluoride (UF6); these are the first and only substance-specific requirements in the IAEA regulations. These requirements have already particularly affected, and will further affect, the transport of non-fissile and fissile excepted UF 6 and the packages used for these transports. Non-fissile and fissile excepted UF6 (ASTM C 787) has been transported worldwide for decades in a safe and reliable manner, using internationally standardised packages. Under the auspices of the World Nuclear Transport Institute (WNTI), an industry working group has been evaluating the existing packages against the requirements in TS-R-1. As new requirements came into effect, there were new challenges for the use of these standard packages, including the free drop test and the thermal requirements. In close cooperation with the WNTI HEXT Industry Working Group, a consortium of UF6 producers/users has worked together on the design and development, testing and certification of technical solutions for modification and optimisation of the existing packages to comply with TS-R-1. This paper reviews the existing standard packages against the requirements in TS-R-1. An update is also given describing the enhancements to the standard packages that have been designed and developed recently. The paper also describes how these solutions have been tested and certified, as well as the status of implementation. Finally, a review is made of the options that are available internationally to transport UF6 in compliance with TS-R-1. (author)

  15. A 1D coordination polymer of UF{sub 5} with HCN as a ligand

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Benjamin; Rudel, Stefan S.; Buchner, Magnus R.; Kraus, Florian [Fachbereich Chemie, Philipps-Universitaet Marburg (Germany); Karttunen, Antti J. [Department of Chemistry, Aalto University (Finland)

    2017-01-05

    β-Uranium(V) fluoride was reacted with liquid anhydrous hydrogen cyanide to obtain a 1D coordination polymer with the composition {sup 1}{sub ∞}[UF{sub 5}(HCN){sub 2}], {sup 1}{sub ∞}[UF{sub 4/1}F{sub 2/2}-(HCN){sub 2/1}], revealed by single-crystal X-ray structure determination. The reaction system was furthermore studied by means of vibrational and NMR spectroscopy, as well as by quantum chemical calculations. The compound presents the first described polymeric HCN Lewis adduct and the first HCN adduct of a uranium fluoride. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Confirmatory measurements of UF6 using the neutron self-interrogation method

    International Nuclear Information System (INIS)

    Stewart, J.E.; Ensslin, N.; Menlove, H.O.; Cowder, L.R.; Polk, P.J.

    1985-01-01

    A passive neutron counting method has been developed for measurement of the 235 U mass in Model 5A cylinders of UF 6 . The unique neutronic properties of UF 6 containing highly enriched uranium (HEU) permit 235 U assay using only passive neutron counting. The sample effectively assays itself by self-interrogation. Shipped from enrichment plants and received at fuel fabrication and conversion facilities, 5A UF 6 cylinders hold up to approx.17 kg of 235 U each. Field measurements at the Portsmouth Gaseous Diffusion Plant (GDP) showed an average assay accuracy of 6.8% (1sigma) for 44 cylinders with enrichments from 6 to 98% and with a range of fill heights. Further measurements on 38 cylinders containing 97%-enriched material yielded an accuracy of 2.8% (1sigma). Typical counting times for these measurements were less than 5 min. An in-plant instrument for receipts confirmation measurements of 5A UF 6 cylinders has been developed for the Savannah River Plant. The Receipts Assay Monitor (RAM) is currently being tested and calibrated. It is designed to confirm declared fissile mass in all incoming 5A cylinders containing HEU in the form of UF 6 . One of the computer-controlled features is a removable cadmium liner for the sample cavity. The liner allows a sample fill-height correction, which significantly improves assay accuracy

  17. MF/UF rejection and fouling potential of algal organic matter from bloom-forming marine and freshwater algae

    KAUST Repository

    Villacorte, Loreen O.

    2015-07-01

    Pretreatment with microfiltration (MF) or ultrafiltration (UF) membranes has been proposed for seawater reverse osmosis (SWRO) plants to address operational issues associated with algal blooms. Here, we investigated the MF/UF rejection and fouling potential of algal organic matter (AOM) released by common species of bloom-forming marine (Alexandrium tamarense and Chaetoceros affinis) and freshwater (Microcystis sp.) algae. Batch culture monitoring of the three algal species illustrated varying growth pattern, cell concentration, AOM released and membrane fouling potential. The high membrane fouling potential of the cultures can be directly associated (R2>0.85) with AOM such as transparent exopolymer particle (TEP) while no apparent relationship with algal cell concentration was observed. The AOM comprised mainly biopolymers (e.g., polysaccharides and proteins) and low molecular weight organic compounds (e.g., humic-like substances). The former were largely rejected by MF/UF membranes while the latter were poorly rejected. MF (0.4μm and 0.1μm pore size) rejected 14%-56% of biopolymers while conventional UF (100kDa) and tight UF (10kDa) rejected up to 83% and 97%, respectively. The retention of AOM resulted in a rapid increase in trans-membrane pressure (δP) over time, characterised by pore blocking followed by cake filtration with enhanced compression as illustrated by an exponential progression of δP. © 2015 Elsevier B.V.

  18. Enthalpy of sublimation/vaporization of trans-cyclohexyl-1,4-diamine and cis-cyclohexyl-1,2-diamine

    International Nuclear Information System (INIS)

    Tome, Luciana I.N.; Rosado, Mario T.S.; Nunes, Sandra C.C.; Maria, Teresa M.R.; Canotilho, Joao; Eusebio, M. Ermelinda S.

    2007-01-01

    The molar enthalpy of sublimation, Δ cr g H m 0 , of trans-cyclohexyl-1,4-diamine and the molar enthalpy of vaporization, Δ l g H m 0 , of cis-cyclohexyl-1,2-diamine, at the temperature 298.15 K, were determined by calorimetry. Δ cr g H m 0 (T=298.15K)=(105.0±0.8)kJ.mol -1 was obtained for the trans-isomer and Δ l g H m 0 (T=298.15K)=(62.2±1.0)kJ.mol -1 for the cis form. The molar enthalpy of fusion of the first compound, at T = 342.1 K, was determined by differential scanning calorimetry. The molar enthalpy of vaporization of the 1,4-isomer was estimated by combining the value of the enthalpy of sublimation with that of the enthalpy of fusion. The values obtained for molar standard enthalpy of vaporization and those available for the enthalpy of the diamines in the gas state were used to calculate the difference between the enthalpies of both compounds in the liquid state

  19. Vapour pressure and enthalpy of vaporization of aliphatic poly-amines

    International Nuclear Information System (INIS)

    Efimova, Anastasia A.; Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Chernyak, Yury

    2010-01-01

    Molar enthalpies of vaporization of aliphatic poly-amines: 1,4-dimethylpiperazine [106-58-1], 1-(2-aminoethyl)-piperazine, [140-31-8], 1-(2-aminoethyl)-4-methyl-piperazine [934-98-5], and triethylenetetramine [112-24-3] were obtained from the temperature dependence of the vapour pressure measured by the transpiration method. A large number of the primary experimental results on temperature dependences of vapour pressures of the parent compounds have been collected from the literature and have been treated uniformly in order to derive vaporization enthalpies of poly-amines at the reference temperature 298.15 K. An internal consistency check was performed on enthalpy of vaporization values for poly-amines studied in this work.

  20. High temperature measurement of water vapor absorption

    Science.gov (United States)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  1. High temperature vapor pressures of stainless steel type 1.4970 and of some other pure metals from laser evaporation

    International Nuclear Information System (INIS)

    Bober, M.; Singer, J.

    1984-10-01

    For the safety analysis of nuclear reactors vapor pressure data of stainless steel are required up to temperatures exceeding 4000 K. In analogy to the classic boiling point method a new technique was developed to measure the high-temperature vapor pressures of stainless steel and other metals from laser vaporization. A fast pyrometer, an ion current probe and an image converter camera are used to detect incipient boiling from the time-temperature curve. The saturated-vapor pressure curves of stainless steel (Type 1.4970), being a cladding material of the SNR 300 breeder reactor, and of molybdenum are experimentally determined in the temperature ranges of 2800-3900 K and 4500-5200 K, respectively. The normal boiling points of iron, nickel, titanium, vanadium and zirconium are verified. Besides, spectral emissivity values of the liquid metals are measured at the pyrometer wavelengths of 752 nm and/or 940 nm. (orig.) [de

  2. 18 years experience on UF{sub 6} handling at Japanese nuclear fuel manufacturer

    Energy Technology Data Exchange (ETDEWEB)

    Fujinaga, H.; Yamazaki, N.; Takebe, N. [Japan Nucelar Fuel Conversion Co., Ltd., Ibaraki (Japan)

    1991-12-31

    In the spring of 1991, a leading nuclear fuel manufacturing company in Japan, celebrated its 18th anniversary. Since 1973, the company has produced over 5000 metric ton of ceramic grade UO{sub 2} powder to supply to Japanese fabricators, without major accident/incident and especially with a successful safety record on UF{sub 6} handling. The company`s 18 years experience on nuclear fuel manufacturing reveals that key factors for the safe handling of UF{sub 6} are (1) installing adequate facilities, equipped with safety devices, (2) providing UF{sub 6} handling manuals and executing them strictly, and (3) repeating on and off the job training for operators. In this paper, equipment and the operation mode for UF{sub 6} processing at their facility are discussed.

  3. Carbon dioxide and water vapor high temperature electrolysis

    Science.gov (United States)

    Isenberg, Arnold O.; Verostko, Charles E.

    1989-01-01

    The design, fabrication, breadboard testing, and the data base obtained for solid oxide electrolysis systems that have applications for planetary manned missions and habitats are reviewed. The breadboard tested contains sixteen tubular cells in a closely packed bundle for the electrolysis of carbon dioxide and water vapor. The discussion covers energy requirements, volume, weight, and operational characteristics related to the measurement of the reactant and product gas compositions, temperature distribution along the electrolyzer tubular cells and through the bundle, and thermal energy losses. The reliability of individual cell performance in the bundle configuration is assessed.

  4. Results of ultrasonic testing evaluations on UF6 storage cylinders

    International Nuclear Information System (INIS)

    Lykins, M.L.

    1997-02-01

    The three site cylinder management program is responsible for the safe storage of the DOE owned UF 6 storage cylinders at PORTS, PGDP and at the K-25 site. To ensure the safe storage of the UF 6 in the cylinders, the structural integrity of the cylinders must be evaluated. This report represents the latest cylinder integrity investigation that utilized wall thickness evaluations to identify thinning due to atmospheric exposure

  5. Fabrication and performance evaluation of a high temperature co-fired ceramic vaporizing liquid microthruster

    International Nuclear Information System (INIS)

    Cheah, Kean How; Low, Kay-Soon

    2015-01-01

    This paper presents the study of a microelectromechanical system (MEMS)-scaled microthruster using ceramic as the structural material. A vaporizing liquid microthruster (VLM) has been fabricated using the high temperature co-fired ceramic (HTCC) technology. The developed microthruster consists of five components, i.e. inlet, injector, vaporizing chamber, micronozzle and microheater, all integrated in a chip with a dimension of 30 mm × 26 mm × 8 mm. In the dry test, the newly developed microheater which is deposited on zirconia substrate consumes 21% less electrical power than those deposited on silicon substrate to achieve a temperature of 100 °C. Heating temperature as high as 409.1 °C can be achieved using just 5 W of electrical power. For simplicity and safety, a functional test of the VLM with water as propellant has been conducted in the laboratory. Full vaporization of water propellant feeding at different flow rates has been successfully demonstrated. A maximum thrust of 633.5 µN at 1 µl s −1 propellant consumption rate was measured using a torsional thrust stand. (paper)

  6. UF{sub 6} tiedowns for truck transport - right way/wrong way

    Energy Technology Data Exchange (ETDEWEB)

    Stout, F.W. Jr. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)

    1991-12-31

    Tiedown systems for truck transport of UF{sub 6} must be defined and controlled to assure the least risk for hauling the material over the highways. This paper and an associated poster display will present the current status of regulatory criteria for tiedowns, analyze the structural stresses involved in tiedowns for two major UF{sub 6} packaging systems, the 21PF series of overpacks and the 48 in. diameter shipping cylinders, and will present photographs showing some {open_quote}right ways{close_quotes} and some {open_quotes}wrong (or risky) ways{close_quotes} currently used for tiedown systems. Risky tiedown methods must be replaced with safer less risky methods to insure the safe transport of UF{sub 6}.

  7. Effect of sweep gas chemistry on vaporization of Li4SiO4

    International Nuclear Information System (INIS)

    Yamawaki, M.; Yamaguchi, K.

    1995-01-01

    Gas/solid equilibria in the system Li 4 SiO 4 -D 2 -D 2 O were studied by means of Knudsen effusion mass spectrometry. A Knudsen effusion mass spectrometer was modified to enable studies of reactions of hydrogen and/or water vapor with ceramic breeder materials. A gas inlet system was constructed to allow the introduction of gases into a platinum Knudsen cell, from which the equilibrated gaseous reaction products effuse. From the experimental results, it has been deduced that the equilibrium constants of vaporization reactions differ correspondingly to the nonstoichiometry of lithium orthosilicate. ((orig.))

  8. Scoping study to expedite development of a field deployable and portable instrument for UF6 enrichment assay

    Energy Technology Data Exchange (ETDEWEB)

    Chan, George; Valentine, John D.; Russo, Richard E.

    2017-09-14

    Sections 3 and 4, respectively. In Section 5, the technological gaps as well as start-of-the-art and commercial off-the-shelf components that can be adopted to expedite the development of a fieldable or portable UF6 enrichment-assay instrument are identified and discussed. Finally, based on the results of the review, requirements and recommendations for developing the next-generation field-deployable instrument for UF6 enrichment assay are presented in Section 6.

  9. Molecular dynamics study of the vaporization of an ionic drop

    Science.gov (United States)

    Galamba, N.

    2010-09-01

    The melting of a microcrystal in vacuum and subsequent vaporization of a drop of NaCl were studied through molecular dynamics simulations with the Born-Mayer-Huggins-Tosi-Fumi rigid-ion effective potential. The vaporization was studied for a single isochor at increasing temperatures until the drop completely vaporized, and gaseous NaCl formed. Examination of the vapor composition shows that the vapor of the ionic drop and gaseous NaCl are composed of neutral species, the most abundant of which, ranging from simple NaCl monomers (ion pairs) to nonlinear polymers, (NanCln)n=2-4. The enthalpies of sublimation, vaporization, and dissociation of the different vapor species are found to be in reasonable agreement with available experimental data. The decrease of the enthalpy of vaporization of the vapor species, with the radius of the drop decrease, accounts for a larger fraction of trimers and tetramers than that inferred from experiments. Further, the rhombic dimer is significantly more abundant than its linear isomer although the latter increases with the temperature. The present results suggest that both trimers and linear dimers may be important to explain the vapor pressure of molten NaCl at temperatures above 1500 K.

  10. A Two-Line Absorption Instrument for Scramjet Temperature and Water Vapor Concentration Measurement in HYPULSE

    Science.gov (United States)

    Tsai, C. Y.

    1998-01-01

    A three beam water vapor sensor system has been modified to provide for near simultaneous temperature measurement. The system employs a tunable diode laser to scan spectral line of water vapor. The application to measurements in a scramjet combustor environment of a shock tunnel facility is discussed. This report presents and discusses die initial calibration of the measurement system.

  11. Influence of the temperature, volume and type of solution in the mercury vaporization of dental amalgam residue

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Raquel dalla [Department of Chemical Engineering, State University of Maringa, Maringa - PR (Brazil)], E-mail: raqueldc_eng@yahoo.com.br; Cossich, Eneida Sala; Tavares, Celia Regina Granhen [Department of Chemical Engineering, State University of Maringa, Maringa - PR (Brazil)

    2008-12-15

    One of the qualitative methods for the identification of mercury vapor is what it occurs as a way of chemical reaction between palladium chloride and metallic mercury. Palladium chloride ribbons with yellowish coloration put in contact with the vaporized mercury of dental amalgam residue, liberates palladium and forms mercury chloride in your surface, and starts to have black coloration; this form identify the presence of the mercury vapor in the system. This work studies the influence of temperature, volume and type of barrier-solution in the vaporization of mercury during the period of storage of dental amalgam residues, aiming to establish the best conditions for storage of these residues. It was found that for all tested solutions, the longest storage times without any occurrence of mercury vaporization were obtained in the lowest temperatures tested and the largest solution volumes of barrier-solution. The radiographic effluent presented bigger efficacy in the reduction of the volatilization, increasing the period when the residue was stored, however the analysis of this solution after the vaporization test showed the presence of organic mercury. These results show that water is the most efficient barrier against the vaporization of mercury, since it did not result in organic mercury formation in the effluent solution from the storage process.

  12. Influence of the temperature, volume and type of solution in the mercury vaporization of dental amalgam residue

    International Nuclear Information System (INIS)

    Costa, Raquel dalla; Cossich, Eneida Sala; Tavares, Celia Regina Granhen

    2008-01-01

    One of the qualitative methods for the identification of mercury vapor is what it occurs as a way of chemical reaction between palladium chloride and metallic mercury. Palladium chloride ribbons with yellowish coloration put in contact with the vaporized mercury of dental amalgam residue, liberates palladium and forms mercury chloride in your surface, and starts to have black coloration; this form identify the presence of the mercury vapor in the system. This work studies the influence of temperature, volume and type of barrier-solution in the vaporization of mercury during the period of storage of dental amalgam residues, aiming to establish the best conditions for storage of these residues. It was found that for all tested solutions, the longest storage times without any occurrence of mercury vaporization were obtained in the lowest temperatures tested and the largest solution volumes of barrier-solution. The radiographic effluent presented bigger efficacy in the reduction of the volatilization, increasing the period when the residue was stored, however the analysis of this solution after the vaporization test showed the presence of organic mercury. These results show that water is the most efficient barrier against the vaporization of mercury, since it did not result in organic mercury formation in the effluent solution from the storage process

  13. Water vapor self-continuum absorption measurements in the 4.0 and 2.1 μm transparency windows

    Science.gov (United States)

    Richard, L.; Vasilchenko, S.; Mondelain, D.; Ventrillard, I.; Romanini, D.; Campargue, A.

    2017-11-01

    In a recent contribution [A. Campargue, S. Kassi, D. Mondelain, S. Vasilchenko, D. Romanini, Accurate laboratory determination of the near infrared water vapor self-continuum: A test of the MT_CKD model. J. Geophys. Res. Atmos., 121,13,180-13,203, doi:10.1002/2016JD025531], we reported accurate water vapor absorption continuum measurements by Cavity Ring-down Spectroscopy (CRDS) and Optical-Feedback-Cavity Enhanced Absorption Spectroscopy (OF-CEAS) at selected spectral points of 4 near infrared transparency windows. In the present work, the self-continuum cross-sections, CS, are determined for two new spectral points. The 2491 cm-1 spectral point in the region of maximum transparency of the 4.0 μm window was measured by OF-CEAS in the 23-52 °C temperature range. The 4435 cm-1 spectral point of the 2.1 μm window was measured by CRDS at room temperature. The self-continuum cross-sections were determined from the pressure squared dependence of the continuum absorption. Comparison to the literature shows a reasonable agreement with 1970 s and 1980 s measurements using a grating spectrograph in the 4.0 μm window and a very good consistency with our previous laser measurements in the 2.1 μm window. For both studied spectral points, our values are much smaller than previous room temperature measurements by Fourier Transform Spectroscopy. Significant deviations (up to about a factor 4) are noted compared to the widely used semi empirical MT_CKD model of the absorption continuum. The measured temperature dependence at 2491 cm-1 is consistent with previous high temperature measurements in the 4.0 μm window and follows an exp(D0/kT) law, D0 being the dissociation energy of the water dimer.

  14. Near-infrared diode laser absorption diagnostic for temperature and water vapor in a scramjet combustor

    International Nuclear Information System (INIS)

    Liu, Jonathan T.C.; Rieker, Gregory B.; Jeffries, Jay B.; Gruber, Mark R.; Carter, Campbell D.; Mathur, Tarun; Hanson, Ronald K.

    2005-01-01

    Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34-1.47 μm spectral region (2v1and v1+ v3overtone bands). Ratio thermometry was performed using direct-absorption wavelength scans of isolated features at a 4-kHz repetition rate, as well as 2f wavelength modulation scans at a 2-kHz scan rate. Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise. Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity. The use of three water vapor absorption features allowed for preliminary estimates of temperature distributions along the line of sight. The improved signal quality afforded by 2f measurements, in the case of weak absorption, demonstrates the utility of a scanned wavelength modulation strategy in such situations

  15. Growth behavior of LiMn{sub 2}O{sub 4} particles formed by solid-state reactions in air and water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Kozawa, Takahiro, E-mail: t-kozawa@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11–1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yanagisawa, Kazumichi [Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, 2–5-1 Akebono-cho, Kochi 780-8520 (Japan); Murakami, Takeshi; Naito, Makio [Joining and Welding Research Institute, Osaka University, 11–1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2016-11-15

    Morphology control of particles formed during conventional solid-state reactions without any additives is a challenging task. Here, we propose a new strategy to control the morphology of LiMn{sub 2}O{sub 4} particles based on water vapor-induced growth of particles during solid-state reactions. We have investigated the synthesis and microstructural evolution of LiMn{sub 2}O{sub 4} particles in air and water vapor atmospheres as model reactions; LiMn{sub 2}O{sub 4} is used as a low-cost cathode material for lithium-ion batteries. By using spherical MnCO{sub 3} precursor impregnated with LiOH, LiMn{sub 2}O{sub 4} spheres with a hollow structure were obtained in air, while angulated particles with micrometer sizes were formed in water vapor. The pore structure of the particles synthesized in water vapor was found to be affected at temperatures below 700 °C. We also show that the solid-state reaction in water vapor is a simple and valuable method for the large-scale production of particles, where the shape, size, and microstructure can be controlled. - Graphical abstract: This study has demonstrated a new strategy towards achieving morphology control without the use of additives during conventional solid-state reactions by exploiting water vapor-induced particle growth. - Highlights: • A new strategy to control the morphology of LiMn{sub 2}O{sub 4} particles is proposed. • Water vapor-induced particle growth is exploited in solid-state reactions. • The microstructural evolution of LiMn{sub 2}O{sub 4} particles is investigated. • The shape, size and microstructure can be controlled by solid-state reactions.

  16. Vapor-based interferometric measurement of local evaporation rate and interfacial temperature of evaporating droplets.

    Science.gov (United States)

    Dehaeck, Sam; Rednikov, Alexey; Colinet, Pierre

    2014-03-04

    The local evaporation rate and interfacial temperature are two quintessential characteristics for the study of evaporating droplets. Here, it is shown how one can extract these quantities by measuring the vapor concentration field around the droplet with digital holographic interferometry. As a concrete example, an evaporating freely receding pending droplet of 3M Novec HFE-7000 is analyzed at ambient conditions. The measured vapor cloud is shown to deviate significantly from a pure-diffusion regime calculation, but it compares favorably to a new boundary-layer theory accounting for a buoyancy-induced convection in the gas and the influence upon it of a thermal Marangoni flow. By integration of the measured local evaporation rate over the interface, the global evaporation rate is obtained and validated by a side-view measurement of the droplet shape. Advective effects are found to boost the global evaporation rate by a factor of 4 as compared to the diffusion-limited theory.

  17. Vapor-solid-solid grown Ge nanowires at integrated circuit compatible temperature by molecular beam epitaxy

    Science.gov (United States)

    Zhu, Zhongyunshen; Song, Yuxin; Zhang, Zhenpu; Sun, Hao; Han, Yi; Li, Yaoyao; Zhang, Liyao; Xue, Zhongying; Di, Zengfeng; Wang, Shumin

    2017-09-01

    We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy at the substrate temperature of ˜180 °C, which is compatible with the temperature window for Si-based integrated circuit. Low temperature grown Ge NWs hold a smaller size, similar uniformity, and better fit with Au tips in diameter, in contrast to Ge NWs grown at around or above the eutectic temperature of Au-Ge alloy in the vapor-liquid-solid (VLS) growth. Six ⟨110⟩ growth orientations were observed on Ge (110) by the VSS growth at ˜180 °C, differing from only one vertical growth direction of Ge NWs by the VLS growth at a high temperature. The evolution of NWs dimension and morphology from the VLS growth to the VSS growth is qualitatively explained by analyzing the mechanism of the two growth modes.

  18. The vapor pressure and enthalpy of vaporization of M-xylene

    International Nuclear Information System (INIS)

    Rothenberg, S.J.; Seiler, F.A.; Bechtold, W.E.; Eidson, A.F.

    1988-01-01

    We measured the vapor pressure of m-xylene over the temperature range 273 to 293 deg K with a single-sided capacitance manometer. The enthalpy of vaporization was 42.2 ± 0.1 (SE) kj/ g·mol. Combining our own data with previously published data, we recommend using the values 42.0, 40.6, and 39.1 (± 0.1) (SE) kjg·mol for the enthalpy of vaporization of m-xylene at 300, 340, and 380 deg. K, respectively, and a value for the change in heat capacity on vaporization (ΔCpdeg.) of 35 ± 3 (SE) J/g·mol·K over the temperature range studied. (author)

  19. The Comparing Options for Management: Patient-centered Results for Uterine Fibroids (COMPARE-UF) Registry: Rationale and Design.

    Science.gov (United States)

    Stewart, Elizabeth A; Lytle, Barbara L; Thomas, Laine; Wegienka, Ganesa R; Jacoby, Vanessa; Diamond, Michael P; Nicholson, Wanda K; Anchan, Raymond M; Venable, Sateria; Wallace, Kedra; Marsh, Erica E; Maxwell, George L; Borah, Bijan J; Catherino, William H; Myers, Evan R

    2018-05-08

    To design and establish a uterine fibroid (UF) registry based in the United States (US) to provide comparative effectiveness data regarding UF treatment. We report here the design and initial recruitment for the Comparing Options for Management: Patient-centered Results for Uterine Fibroids (COMPARE-UF) registry (Clinicaltrials.gov, NCT02260752), funded by the Agency for Healthcare Research and Quality (AHRQ) in collaboration with the-Patient-Centered Outcomes Research Institute (PCORI). COMPARE-UF is designed to help answer critical questions about treatment options for women with symptomatic UF. Women undergoing a procedure for UF (hysterectomy, myomectomy [abdominal, hysteroscopic, vaginal and laparoscopic/robotic], endometrial ablation, radiofrequency fibroid ablation, uterine artery embolization, magnetic resonance guided focused ultrasound or progestin-releasing intrauterine device insertion) at one of the COMPARE-UF sites are invited to participate in a prospective registry with three years follow-up for post-procedural outcomes. Enrolled participants provide annual follow-up through an online portal or through traditional phone contact. A central data abstraction center provides information obtained from imaging, operative or procedural notes and pathology reports. Women with uterine fibroids and other stakeholders are a key part of the COMPARE-UF registry and participate at all points from study design to dissemination of results. We built a network of nine clinical sites across the US with expertise in the care of women with UF to capture geographic, racial, ethnic and procedural diversity. Of the initial 2031 women enrolled in COMPARE-UF, 42% are self-identified as Black or African-American and 40% are age 40 years or younger with 16% of participants under age 35. Women undergoing myomectomy comprise the largest treatment group at 46% of all procedures with laparoscopic or robotic myomectomy comprising the largest subset of myomectomies at 19% of all

  20. A Micro-Preconcentrator Combined Olfactory Sensing System with a Micromechanical Cantilever Sensor for Detecting 2,4-Dinitrotoluene Gas Vapor

    Directory of Open Access Journals (Sweden)

    Myung-Sic Chae

    2015-07-01

    Full Text Available Preventing unexpected explosive attacks and tracing explosion-related molecules require the development of highly sensitive gas-vapor detection systems. For that purpose, a micromechanical cantilever-based olfactory sensing system including a sample preconcentrator was developed to detect 2,4-dinitrotoluene (2,4-DNT, which is a well-known by-product of the explosive molecule trinitrotoluene (TNT and exists in concentrations on the order of parts per billion in the atmosphere at room temperature. A peptide receptor (His-Pro-Asn-Phe-Ser-Lys-Tyr-Ile-Leu-His-Gln-Arg that has high binding affinity for 2,4-DNT was immobilized on the surface of the cantilever sensors to detect 2,4-DNT vapor for highly selective detection. A micro-preconcentrator (µPC was developed using Tenax-TA adsorbent to produce higher concentrations of 2,4-DNT molecules. The preconcentration was achieved via adsorption and thermal desorption phenomena occurring between target molecules and the adsorbent. The µPC directly integrated with a cantilever sensor and enhanced the sensitivity of the cantilever sensor as a pretreatment tool for the target vapor. The response was rapidly saturated within 5 min and sustained for more than 10 min when the concentrated vapor was introduced. By calculating preconcentration factor values, we verified that the cantilever sensor provides up to an eightfold improvement in sensing performance.

  1. Estimation of time to rupture in a fire using 6FIRE, a lumped parameter UF6 cylinder transient heat transfer/stress analysis model

    International Nuclear Information System (INIS)

    Williams, W.R.; Anderson, J.C.

    1995-01-01

    The transportation of UF 6 is subject to regulations requiring the evaluation of packaging under a sequence of hypothetical accident conditions including exposure to a 30-min 800 degree C (1475 degree F) fire [10 CFR 71.73(c)(3)]. An issue of continuing interest is whether bare cylinders can withstand such a fire without rupturing. To address this issue, a lumped parameter heat transfer/stress analysis model (6FIRE) has been developed to simulate heating to the point of rupture of a cylinder containing UF 6 when it is exposed to a fire. The model is described, then estimates of time to rupture are presented for various cylinder types, fire temperatures, and fill conditions. An assessment of the quantity of UF 6 released from containment after rupture is also presented. Further documentation of the model is referenced

  2. Integrating UF6 Cylinder RF Tracking With Continuous Load Cell Monitoring for Verifying Declared UF6 Feed and Withdrawal Operations Verifying Declared UF6 Feed and Withdrawal Operations

    International Nuclear Information System (INIS)

    Krichinsky, Alan M.; Miller, Paul; Pickett, Chris A.; Richardson, Dave; Rowe, Nathan C.; Whitaker, J. Michael; Younkin, James R.

    2009-01-01

    Oak Ridge National Laboratory is demonstrating the integration of UF6 cylinder tracking, using RF technology, with continuous load cell monitoring (CLCM) at mock UF6 feed and withdrawal (F and W) stations. CLCM and cylinder tracking are two of several continuous-monitoring technologies that show promise in providing integrated safeguards of F and W operations at enrichment plants. Integrating different monitoring technologies allows advanced, automated event processing to screen innocuous events thereby minimizing false alerts to independent inspectors. Traditionally, international inspectors rely on batch verification of material inputs and outputs derived from operator declarations and periodic on-site inspections at uranium enrichment plants or other nuclear processing facilities. Continuously monitoring F and W activities between inspections while providing filtered alerts of significant operational events will substantially increase the amount of valuable information available to inspectors thereby promising to enhance the effectiveness of safeguards and to improve efficiency in conducting on-site inspections especially at large plants for ensuring that all operations are declared.

  3. Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

    Science.gov (United States)

    Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

    2007-01-01

    A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

  4. Long-term trends in stratospheric ozone, temperature, and water vapor over the Indian region

    Directory of Open Access Journals (Sweden)

    S. T. Akhil Raj

    2018-01-01

    Full Text Available We have investigated the long-term trends in and variabilities of stratospheric ozone, water vapor and temperature over the Indian monsoon region using the long-term data constructed from multi-satellite (Upper Atmosphere Research Satellite (UARS MLS and HALOE, 1993–2005, Aura Microwave Limb Sounder (MLS, 2004–2015, Sounding of the Atmosphere using Broadband Emission Radiometry (SABER, 2002–2015 on board TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics observations covering the period 1993–2015. We have selected two locations, namely, Trivandrum (8.4° N, 76.9° E and New Delhi (28° N, 77° E, covering northern and southern parts of the Indian region. We also used observations from another station, Gadanki (13.5° N, 79.2° E, for comparison. A decreasing trend in ozone associated with NOx chemistry in the tropical middle stratosphere is found, and the trend turned to positive in the upper stratosphere. Temperature shows a cooling trend in the stratosphere, with a maximum around 37 km over Trivandrum (−1.71 ± 0.49 K decade−1 and New Delhi (−1.15 ± 0.55 K decade−1. The observed cooling trend in the stratosphere over Trivandrum and New Delhi is consistent with Gadanki lidar observations during 1998–2011. The water vapor shows a decreasing trend in the lower stratosphere and an increasing trend in the middle and upper stratosphere. A good correlation between N2O and O3 is found in the middle stratosphere (∼ 10 hPa and poor correlation in the lower stratosphere. There is not much regional difference in the water vapor and temperature trends. However, upper stratospheric ozone trends over Trivandrum and New Delhi are different. The trend analysis carried out by varying the initial year has shown significant changes in the estimated trend.

  5. The vapor pressures of explosives

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, Robert G.; Waltman, Melanie J.; Atkinson, David A.; Grate, Jay W.; Hotchkiss, Peter

    2013-01-05

    The vapor pressures of many explosive compounds are extremely low and thus determining accurate values proves difficult. Many researchers, using a variety of methods, have measured and reported the vapor pressures of explosives compounds at single temperatures, or as a function of temperature using vapor pressure equations. There are large variations in reported vapor pressures for many of these compounds, and some errors exist within individual papers. This article provides a review of explosive vapor pressures and describes the methods used to determine them. We have compiled primary vapor pressure relationships traceable to the original citations and include the temperature ranges for which they have been determined. Corrected values are reported as needed and described in the text. In addition, after critically examining the available data, we calculate and tabulate vapor pressures at 25 °C.

  6. Molecular dynamics study of the vaporization of an ionic drop.

    Science.gov (United States)

    Galamba, N

    2010-09-28

    The melting of a microcrystal in vacuum and subsequent vaporization of a drop of NaCl were studied through molecular dynamics simulations with the Born-Mayer-Huggins-Tosi-Fumi rigid-ion effective potential. The vaporization was studied for a single isochor at increasing temperatures until the drop completely vaporized, and gaseous NaCl formed. Examination of the vapor composition shows that the vapor of the ionic drop and gaseous NaCl are composed of neutral species, the most abundant of which, ranging from simple NaCl monomers (ion pairs) to nonlinear polymers, (Na(n)Cl(n))(n=2-4). The enthalpies of sublimation, vaporization, and dissociation of the different vapor species are found to be in reasonable agreement with available experimental data. The decrease of the enthalpy of vaporization of the vapor species, with the radius of the drop decrease, accounts for a larger fraction of trimers and tetramers than that inferred from experiments. Further, the rhombic dimer is significantly more abundant than its linear isomer although the latter increases with the temperature. The present results suggest that both trimers and linear dimers may be important to explain the vapor pressure of molten NaCl at temperatures above 1500 K.

  7. A technique to depress desflurane vapor pressure.

    Science.gov (United States)

    Brosnan, Robert J; Pypendop, Bruno H

    2006-09-01

    To determine whether the vapor pressure of desflurane could be decreased by using a solvent to reduce the anesthetic molar fraction in a solution (Raoult's Law). We hypothesized that such an anesthetic mixture could produce anesthesia using a nonprecision vaporizer instead of an agent-specific, electronically controlled, temperature and pressure compensated vaporizer currently required for desflurane administration. One healthy adult female dog. Propylene glycol was used as a solvent for desflurane, and the physical characteristics of this mixture were evaluated at various molar concentrations and temperatures. Using a circle system with a breathing bag attached at the patient end and a mechanical ventilator to simulate respiration, an in-circuit, nonprecision vaporizer containing 40% desflurane and 60% propylene glycol achieved an 11.5% +/- 1.0% circuit desflurane concentration with a 5.2 +/- 0.4 (0 = off, 10 = maximum) vaporizer setting. This experiment was repeated with a dog attached to the breathing circuit under spontaneous ventilation with a fresh gas flow of 0.5 L minute(-1). Anesthesia was maintained for over 2 hours at a mean vaporizer setting of 6.2 +/- 0.4, yielding mean inspired and end-tidal desflurane concentrations of 8.7% +/- 0.5% and 7.9% +/- 0.7%, respectively. Rather than alter physical properties of vaporizers to suit a particular anesthetic agent, this study demonstrates that it is also possible to alter physical properties of anesthetic agents to suit a particular vaporizer. However, propylene glycol may not prove an ideal solvent for desflurane because of its instability in solution and substantial-positive deviation from Raoult's Law.

  8. Molecular composition of vapor in the NaF-ZrF4 system

    International Nuclear Information System (INIS)

    Korenev, Yu.M.; Sidorov, L.N.; Rykov, A.N.; Novoselova, A.V.

    1980-01-01

    The NaF-ZrF 4 system is studied. It is established that Na 2 ZrF 6 , NaZrF 5 , (NaZrF 5 ) 2 , NaZr 2 F 9 complex molecules are present in the saturated vapor alongside with pure components. Partial pressures of all vapor components are determined. The values of partial pressure and evaporation heat have been used to calculate the vapor composition above the system; T-x and P-T projections of the phase diagram of the NaF-ZrF 4 system are plotted

  9. The vapor pressure and enthalpy of vaporization of M-xylene

    Energy Technology Data Exchange (ETDEWEB)

    Rothenberg, S J; Seiler, F A; Bechtold, W E; Eidson, A F

    1988-12-01

    We measured the vapor pressure of m-xylene over the temperature range 273 to 293 deg K with a single-sided capacitance manometer. The enthalpy of vaporization was 42.2 {+-} 0.1 (SE) kj/ g{center_dot}mol. Combining our own data with previously published data, we recommend using the values 42.0, 40.6, and 39.1 ({+-} 0.1) (SE) kjg{center_dot}mol for the enthalpy of vaporization of m-xylene at 300, 340, and 380 deg. K, respectively, and a value for the change in heat capacity on vaporization ({delta}Cpdeg.) of 35 {+-} 3 (SE) J/g{center_dot}mol{center_dot}K over the temperature range studied. (author)

  10. The applicability of fluoride volatility process to producing UF6 from yellow cake

    International Nuclear Information System (INIS)

    Xia Dechang

    2005-01-01

    The schematic diagrams producing UF 6 from yellow cake are showed in this paper. The characteristics and process improvements of the fluoride volatility process are explained. The applicability of the fluoride volatility process to producing UF 6 from yellow cake is discussed. (authors)

  11. Raman scattering temperature measurements for water vapor in nonequilibrium dispersed two-phase flow

    International Nuclear Information System (INIS)

    Anastasia, C.M.; Neti, S.; Smith, W.R.; Chen, J.C.

    1982-09-01

    The objective of this investigation was to determine the feasibility of using Raman scattering as a nonintrusive technique to measure vapor temperatures in dispersed two-phase flow. The Raman system developed for this investigation is described, including alignment of optics and optimization of the photodetector for photon pulse counting. Experimentally obtained Raman spectra are presented for the following single- and two-phase samples: liquid water, atmospheric nitrogen, superheated steam, nitrogen and water droplets in a high void fraction air/water mist, and superheated water vapor in nonequilibrium dispersed flow

  12. Uranium/water vapor reactions in gaseous atmospheres

    International Nuclear Information System (INIS)

    Jackson, R.L.; Condon, J.B.; Steckel, L.M.

    1977-07-01

    Experiments have been performed to determine the effect of varying humidities, gaseous atmospheres, and temperatures on the uranium/water vapor reaction. A balance, which allowed continuous in-system weighings, was used to determine the rates of the uranium/water vapor reactions at water vapor pressures of 383, 1586, and 2853 Pa and at temperatures of 80, 100, and 150 0 C in atmospheres of hydrogen, argon, or argon/oxygen mixtures. Based on rate data, the reactions were characterized as hydriding or nonhydriding. Hydriding reactions were found to be preferred in moist hydrogen systems at the higher temperatures and the lower humidities. The presence of hydrogen in hydriding systems was found to initially inhibit the reaction, but causes an acceleration of the rate in the final stages. In general, reaction rates of hydriding systems approached the hydriding rates calculated and observed in dry hydrogen. Hydriding and nonhydriding reaction rates showed a positive correlation to temperature and water vapor pressure. Final reaction rates in moist argon/oxygen mixtures of 1.93, 4.57, and 9.08 mole percent oxygen were greater than the rates observed in moist hydrogen or argon. Final reaction rates were negatively correlated to the oxygen concentration

  13. Evaluation of tecniques for controlling UF6 release clouds in the GAT environmental chamber

    International Nuclear Information System (INIS)

    Lux, C.J.

    1982-01-01

    Studies designed to characterize the reaction between UF 6 and atmospheric moisture, evaluate environmental variables of UF 6 cloud formation and ultimate cloud fate, and UF 6 release cloud control procedure have been conducted in the 1200 cu. ft. GAT environmental chamber. In earlier chamber experiments, 30 separate UF 6 release tests indicated that variations of atmospheric conditions and sample sizes had no significant effect on UO 2 F 2 particle size distribution, release cloud formation, or cloud settling rates. During the past year, numerous procedures have been evaluated for accelerating UF 6 cloud knockdown in a series of 37 environmental chamber releases. Knockdown procedures included: coarse water spray; air jet; steam spray (electrostatically charged and uncharged); carbon dioxide; Freon-12; fine water mist (uncharged); boric acid mist (charged and uncharged); and an ionized dry air stream. UF 6 hydrolysis cloud settling rates monitored by a laser/powermeter densitometer, indicated the relative effectiveness of various cloud knockdown techniques. Electrostatically charged boric acid/water mist, and electrostatically ionized dry air were both found to be very effective, knocking down the UO 2 F 2 release cloud particles in two to five minutes. Work to adapt these knockdown techniques for use under field conditions is continuing, taking into account recovery of the released uranium as well as nuclear criticality constraints

  14. The rates and mechanisms of water exchange of actinide aqua ions: A variable temperature 17O NMR study of U(H2O)104+, UF(H2O)93+, and Th(H2O)104+

    International Nuclear Information System (INIS)

    Farkas, I.; Grenthe, I.; Banyai, I.

    2000-01-01

    The rate constants and the activation parameters for the exchange between water solvent and [U(H 2 O) 10 ] 4+ and [UF(H 2 O) 9 ] 3+ , and a lower limit for the rate constant at room temperature for [Th(H 2 O) 10 ] 4+ , were determined by 17 O NMR spectroscopy in the temperature range 255--305 K. The experiments were made at different constant hydrogen ion concentrations, which varied between 0.16 and 0.8 mol kg -1 . The Th(IV) system was investigated using Tb 3+ as a shift reagent. The following kinetic parameters at 25 C were obtained: k ex = (5.4 ± 0.6) 10 6 x -1 , ΔH double dagger = 34 ± 3 kJ mol -1 , ΔS ++ = -16 ± 10 J mol -1 K -1 for U 4+ (aq), k ex = (5.5 ± 0.7) 10 6 x -1 , ΔH d ouble dagger = 34 ± 3 kJ mol -1 , ΔS ++ = 3 ± 15 J mol -1 K -1 for UF 3+ (Iaq), and k ex > 5 10 7 s -1 for Th 4+ (aq), where the uncertainty is given at the 2σ-level. This is the first experimental information on the kinetic parameters for the exchange of water for any M 4+ ion. There is no information on the rates and mechanisms of ligand substitutions involving other mono-dentate ligands, hence the mechanistic interpretation of the data is by necessity provisional. The kinetic data and the known ground-state geometry with a coordination number of 10 ± 1 for the Th(IV) and U(IV) complexes suggest a dissociatively activated interchange mechanism. There is no noticeable effect of coordination of one fluoride or one hydroxide to U(IV) on the water exchange rate. This is unusual, for other metal ions there is a strong labilizing of coordinated water when a second ligand is bonded, e.g., in complexes of aluminum and some d-transition elements. In previous studies of the rates and mechanisms of ligand exchange in uranium (VI) systems the authors found a strong decrease in the lability of coordinated water in some fluoride containing complexes

  15. Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

    Science.gov (United States)

    Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

    1991-01-01

    Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

  16. Effect of gamma irradiation and vapor gard on keeping quality of fuerte avocado fruits stored at temperature

    International Nuclear Information System (INIS)

    Awad, S.M.; Hassan, A.K.

    1993-01-01

    'Fuerte'avocado fruits, at mature stage, were treated after harvest by gamma rays and Vapor-Gard either alone or in combination, and stored at room temperature. Irradiation with 0.025 or 0.05 kGy increased loss of weight and decay percentage. However, fruit firmness, total carotenoids content, total phenolic compounds and total carbohydrates content were not affected. In all Vapor-Gard treatments at 0.5 or 1.0% either alone or combined with irradiation decreased the weight loss, decay percentage and total carotenoids content, but increased significantly each of fruit firmness, total phenols content and total carbohydrates content during storage periods. Avocados treated by Vapor-Gard at 0.5 or 1.0% alone or combined with irradiation delayed the ripening and extended shelf by 4 and 8 days respectively compared with those of the control or irradiated fruits which reached the fair quality after 8 days of storage. Concerning the changes in oil properties, it is noticed that, refractive index at 25 degree C and iodine value of avocado oil were not affected by treatments or storage periods, while storage periods caused a noticeable decrease in the free fatty acid percentage in all treatments and this reduction was greater in all Vapor-Gard treatments compared with the control.8 tab

  17. Translation and validation of the Uterine Fibroid Symptom and Quality of Life (UFS-QOL questionnaire for the Brazilian Portuguese language

    Directory of Open Access Journals (Sweden)

    Luiz Gustavo Oliveira Brito

    2017-03-01

    Full Text Available ABSTRACT CONTEXT AND OBJECTIVE: Uterine fibroids (UF, also known as leiomyomas, are the most prevalent gynecological tumors. The Uterine Fibroid Symptoms and Quality of Life (UFS-QOL is the only specific questionnaire that assesses symptom intensity and quality-of-life issues for women with symptomatic UF; however, it only exists in the English language. Thus, we aimed to translate and culturally validate the UFS-QOL questionnaire for the Brazilian Portuguese language. DESIGN AND SETTING: Cross-sectional study, Department of Gynecology and Obstetrics, FMRP-USP. METHODS: 113 patients with UF (case group and 55 patients without UF (control group were interviewed using the UFS-QOL questionnaire after translation and cultural adaptation. The Short Form-36 questionnaire was used as a control. Demographic and psychometric variables were analyzed. RESULTS: Women with UF presented higher mean age, body mass index, weight, parity and comorbidities than the control group (P < 0.05. The most prevalent complaints were abnormal uterine bleeding (93.8%, pelvic pain (36.3% and extrinsic compression (10.6% and these presented adequate construct validity regarding UFS-QOL severity (P < 0.05. The UFS-QOL questionnaire presented good internal consistency regarding symptom severity and quality-of-life-related domains (intraclass correlation coefficient, ICC = 0.82/0.88. Structural validity presented correlation coefficients ranging from 0.59 to 0.91. Test-retest comparison did not show differences among the UFS-QOL subscales. After treatment, women with UF presented improvements on all subscales. CONCLUSION: The UFS-QOL questionnaire presented adequate translation to the Brazilian Portuguese language, with good internal consistency, discriminant validity, construct validity, structural validity and responsiveness, along with adequate test-retest results.

  18. The influence of temperature on the polymerization of ethyl cyanoacrylate from the vapor phase

    Energy Technology Data Exchange (ETDEWEB)

    Dadmun, Mark D [ORNL; Algaier, Dana [University of Tennessee, Knoxville (UTK); Baskaran, Durairaj [University of Tennessee, Knoxville (UTK)

    2011-01-01

    The polymerization of ethyl cyanoacrylate fumes from surface bound initiators is an important step in many novel and mature technologies. Understanding the effect of temperature on the rate of poly(ethyl cyanoacrylate) (PECA) growth and its molecular weight during its polymerization from the vapor phase from surface bound initiators provides insight into the important mechanistic aspects that impact the polymerizations success. In these studies, it is shown that the amount of PECA formed during the polymerization of ECA from a latent fingerprint increases with decreasing temperature, while the polymer molecular weight varies little. This is interpreted to be the result of the loosening of the ion pair that initiates the polymer chain growth and resides on the end of the growing polymer chain with decreasing temperature. Comparison of temperature effects and counter-ion studies show that in both cases loosening the ion pair results in the formation of more polymer with similar molecular weight, verifying this interpretation. These results further suggest that lowering the temperature may be an effective method to optimize anionic vapor phase polymerizations, including the improvement of the quality of aged latent prints and preliminary results are presented that substantiate this prediction.

  19. ZnO–PDMS Nanohybrids: A Novel Optical Sensing Platform for Ethanol Vapor Detection at Room Temperature

    KAUST Repository

    Klini, Argyro

    2015-01-08

    © 2014 American Chemical Society. A new optical gas sensor platform based on highly luminescent ZnO-polymer nanohybrids is demonstrated. The nanohybrids consist of ZnO nanoparticles, typically 125 (±25) nm in size, dispersed in an inert cross-linked polydimethylsiloxane (PDMS) matrix. Upon exposure to ethanol-enriched air at room temperature, the nanocomposites exhibit a clear increase in their photoluminescence (PL) emission, which shows a nearly Langmuir dependence on the alcohol vapor pressure. The response time is on the order of 50 s, particularly at low ethanol concentrations. The limit of ethanol vapor detection (LOD) is as low as 0.4 Torr, while the sensor remains unaffected by the presence of water vapor, demonstrating the potential of the ZnO-PDMS system as an optical gas sensing device. The interaction of the ZnO nanoparticles with molecular oxygen plays an essential role on the overall performance of the sensor, as shown in comparative experiments performed in the presence and absence of atmospheric air. Notably, O2 was found to be quite effective in accelerating the sensor recovery process compared to N2 or vacuum.

  20. Vapor-transport of tungsten and its geologic application

    Energy Technology Data Exchange (ETDEWEB)

    Shibue, Y [Hyogo Univ. of Teacher Education, Hyogo (Japan)

    1988-11-10

    The volatility of tungsten in a hydrous system at elevated temperatures and pressures was examined, and a tentative model for the enrichment of tungsten in hydrothermal solutions for the deposits related to granitic activities was proposed. To produce vapor-saturated solution, 17 or 15ml of 20wt% NaCl solution was introduced into an autoclave. Ca(OH){sub 2} for tungsten and H{sub 2}WO{sub 4} for base metals were used as vapor-captures, and run products were identified by X-ray powder diffractometry. The results suggested that the ratio of tungsten to base metals was higher in a vapor phase than in a liquid phase, and more enrichment of tungsten in the vapor phase occurred at higher temperature and pressure under the coexistence of the vapor and liquid phase. The tentative model emphasizing the vapor-transport of tungsten could explain the presence of tungsten deposits without large mineralization of base metals. Geological schematic model for the generation of the hydrothermal solution enriched in tungsten compared with base metals was illustrated based on above mentioned results. 21 refs., 3 figs.

  1. Automation of the Process to Obtain U F4 Powders

    International Nuclear Information System (INIS)

    Fenocchio, A.D

    2001-01-01

    Here is exposed the preliminary analysis of the control system to be implemented in the Production Plant of UF 4 Powders.The work has been done in the electronic laboratory.This implies, the setting of devices (PLC, Temperature Controllers, etc.) and the setting of the communications using the proper protocol.Also is shown a study about the logic for the first part of the conversion process of UF 6 : the evaporation.This study is used to define the methodology to follow in a future PLC program

  2. 1,4-Dioxane Remediation by Extreme Soil Vapor Extraction (XSVE). Screening-Level Feasibility Assessment and Design Tool in Support of 1,4-Dioxane Remediation by Extreme Soil Vapor Extraction (XSVE) ESTCP Project ER 201326

    Science.gov (United States)

    2017-10-01

    USER GUIDE 1,4-Dioxane Remediation by Extreme Soil Vapor Extraction (XSVE) Screening-Level Feasibility Assessment and Design Tool in...Support of 1,4-Dioxane Remediation by Extreme Soil Vapor Extraction (XSVE) ESTCP Project ER-201326 OCTOBER 2017 Rob Hinchee Integrated Science...Technology, Inc. 1509 Coastal Highway Panacea, FL 32346 8/8/2013 - 8/8/2018 10-2017 1,4-Dioxane Remediation by Extreme Soil Vapor Extraction (XSVE) Screening

  3. The effect of water vapor in the reactor cavity in a MHTGR [Modular High Temperature Gas Cooled Reactor] on the radiation heat transfer

    International Nuclear Information System (INIS)

    Cappiello, M.W.

    1991-01-01

    Analyses have been completed to determine the effect of the presence of water vapor in the reactor cavity in a modular high temperature gas cooled reactor on the predicted radiation heat transfer from the vessel wall to the reactor cavity cooling system. The analysis involves the radiation heat transfer between two parallel plates with an absorbing and emitting medium present. Because the absorption in the water vapor is spectrally dependent, the solution is difficult even for simple geometries. A computer code was written to solve the problem using the Monte Carlo method. The code was validated against closed form solutions, and shows excellent agreement. In the analysis of the reactor problem, the results show that the reduction in heat transfer, and the consequent increase in the vessel wall temperature, can be significant. This effect can be cast in terms of a reduction in the wall surface emissivities from 0.8 to 0.59. Because of the insulating effect of the water vapor, increasing the gap distance between the vessel wall and the cooling system will cause the vessel wall temperature to increase further. Care should be taken in the design of the facility to minimize the gap distance and keep temperature increase within allowable limits. 3 refs., 6 figs., 4 tabs

  4. Effect of Furnish on Temperature and Vapor Pressure Behavior in the Center of Mat Panels during Hot Pressing

    Directory of Open Access Journals (Sweden)

    Muhammad Navis Rofii

    2014-07-01

    Full Text Available Particleboard achieves its overall performance characteristics during hot pressing process. As this process is influenced by several factors, particularly temperature and pressure, it is very important to understand the behavior of both. This study investigates the effects of furnish materials on temperature and vapor pressure behavior inside particleboard mat panels during hot pressing. Strand type particles from hinoki and ring-flaker recycled wood particles were used as furnish for laboratory-scale particleboard panels with a target density of 0.76 g/cm³. Mat panels with a moisture content of about 10% were hot pressed at a platen temperature of 180°C and an initial pressure of 3 MPa until the mat center reached the same temperature as the platen. A press monitoring device (PressMAN Lite was used for detecting the temperature and vapor pressure change in the center of the mat panels. The study showed that the furnish type affected the temperature and vapor behavior inside the mat panels. Particleboard made of hinoki strand resulted in a longer plateau time, a higher plateau temperature and a higher gas pressure generated during hot pressing than those of ring-flaker recycled wood particles. Mixed board resulted in values between those of the two other furnish materials.

  5. Analyses of postulated accidental releases of UF6 inside process buildings

    International Nuclear Information System (INIS)

    Oliveira Neto, Jose Messias de; Nunes, Beatriz Guimaraes; Dias, Cristiane

    2009-01-01

    Uranium Hexafluoride is a material used in the various processes which comprise the front end of the nuclear fuel cycle (conversion, enrichment and fuel fabrication). Confinement of UF 6 is a very important safety requirement since this material is highly reactive and presents safety hazards to humans. The present paper discusses the safety relevant aspects of accidental releases of UF 6 inside process confinement buildings. Postulated accidental scenarios are analyzed and their consequences evaluated. Implant releases rates are estimated using computer code predictions. A time dependent homogeneous compartment model is used to predict concentrations of UF 6 , hydrogen fluoride and uranyl fluoride inside a confinement building, as well as to evaluate source terms released to the atmosphere. These source terms can be used as input to atmospheric dispersion models to evaluate consequences to the environment. The results can also be used to define adequate protective measures for emergency situations. (author)

  6. Method and equipment for continuous transformation of UF6 into (NH4)2U2O7

    International Nuclear Information System (INIS)

    Fuller, R.R.

    1975-01-01

    Uranium hexafluoride is, in a three-stage method, transformed into ammonium diuvanate which can be calcined to UO 2 of good ceramic quality. At the solution of UF 6 in water, UO 2 F 2 and HF form in condsiderably acid solution. This aqueous hydrolysis solution is with standardized using NH 4 O 4 (24-29% NH 3 ) at a pH-value between 5.0 and 6.0 and brought into a precipitation tank. The bulk of the ammonium diuvanate then precipitating is drained in the lower portion of the tank and added again to the suspension, close to the surface of the fluid, under intensive pressure. The intensive vigorous revolution of the entire tank content affects the size of the particles and the size of the surface of the precipitating uranate as well. The equipment for the calcination of the ammonium diuvanate is described. The method represents an improvement of the method described in OS 2162578; the pellets produced are more satisfying to critical requirements. (UWI) [de

  7. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  8. Carbon nanosheets by microwave plasma enhanced chemical vapor deposition in CH4-Ar system

    International Nuclear Information System (INIS)

    Wang Zhipeng; Shoji, Mao; Ogata, Hironori

    2011-01-01

    We employ a new gas mixture of CH 4 -Ar to fabricate carbon nanosheets by microwave plasma enhanced chemical vapor deposition at the growth temperature of less than 500 deg. C. The catalyst-free nanosheets possess flower-like structures with a large amount of sharp edges, which consist of a few layers of graphene sheets according to the observation by transmission electron microscopy. These high-quality carbon nanosheets demonstrated a faster electron transfer between the electrolyte and the nanosheet surface, due to their edge defects and graphene structures.

  9. Standard test method for determination of bromine and chlorine in UF6 and uranyl nitrate by X-Ray fluorescence (XRF) spectroscopy

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This method covers the determination of bromine (Br) and chlorine (Cl) in uranium hexafluoride (UF6) and uranyl nitrate solution. The method as written covers the determination of bromine in UF6 over the concentration range of 0.2 to 8 μg/g, uranium basis. The chlorine in UF6 can be determined over the range of 4 to 160 μg/g, uranium basis. Higher concentrations may be covered by appropriate dilutions. The detection limit for Br is 0.2 μg/g uranium basis and for Cl is 4 μg/g uranium basis. 1.2 This standard may involve hazardous materials, operations and equipment. 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 this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  10. Vapor Pressure Data and Analysis for Selected Organophosphorus Compounds, CMMP, DPMP, DMEP, and DEEP: Extrapolation of High-Temperature Data

    Science.gov (United States)

    2018-04-01

    comparison. The correlation equations are presented using two common units systems , one with temperature given in kelvin (T) and pressure in pascal...This report documents vapor pressure data and correlations for four phosphonate ester compounds that have molecular structures similar to those of...Antoine equation Clausius–Clapeyron equation Enthalpy of vaporization Volatility Differential scanning calorimetry (DSC) Vapor saturation Normal boiling

  11. Review of models used for determining consequences of UF6 release: Model evaluation report. Volume 2

    International Nuclear Information System (INIS)

    Nair, S.K.; Chambers, D.B.; Park, S.H.; Radonjic, Z.R.; Coutts, P.T.; Lewis, C.J.; Hammonds, J.S.; Hoffman, F.O.

    1997-11-01

    Three uranium hexafluoride-(UF 6 -) specific models--HGSYSTEM/UF 6 , Science Application International Corporation, and RTM-96; three dense-gas models--DEGADIS, SLAB, and the Chlorine Institute methodology; and one toxic chemical model--AFTOX--are evaluated on their capabilities to simulate the chemical reactions, thermodynamics, and atmospheric dispersion of UF 6 released from accidents at nuclear fuel-cycle facilities, to support Integrated Safety Analysis, Emergency Response Planning, and Post-Accident Analysis. These models are also evaluated for user-friendliness and for quality assurance and quality control features, to ensure the validity and credibility of the results. Model performance evaluations are conducted for the three UF 6 -specific models, using field data on releases of UF 6 and other heavy gases. Predictions from the HGSYSTEM/UF 6 and SAIC models are within an order of magnitude of the field data, but the SAIC model overpredicts beyond an order of magnitude for a few UF 6 -specific data points. The RTM-96 model provides overpredictions within a factor of 3 for all data points beyond 400 m from the source. For one data set, however, the RTM-96 model severely underpredicts the observations within 200 m of the source. Outputs of the models are most sensitive to the meteorological parameters at large distances from the source and to certain source-specific and meteorological parameters at distances close to the source. Specific recommendations are being made to improve the applicability and usefulness of the three models and to choose a specific model to support the intended analyses. Guidance is also provided on the choice of input parameters for initial dilution, building wake effects, and distance to completion of UF 6 reaction with water

  12. Handling of UF6 in U.S. gaseous diffusion plants

    International Nuclear Information System (INIS)

    Legeay, A.J.

    1978-01-01

    A comprehensive systems analysis of UF 6 handling has been made in the three U.S. gaseous diffusion plants and has resulted in a significant impact on the equipment design and the operating procedures of these facilities. The equipment, facilities, and industrial practices in UF 6 handling operations as they existed in the early 1970's are reviewed with particular emphasis placed on the changes which have been implemented. The changes were applied to the systems and operating methods which evolved from the design, startup, and operation of the Oak Ridge Gaseous Diffusion Plant in 1945

  13. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  14. An axial heat transfer analytical model for capillary-pumped loop vapor line temperature distributions

    International Nuclear Information System (INIS)

    Lin, H.-W.; Lin, W.-K.

    2007-01-01

    This paper aims to study the capillary-pumped loop (CPL) vapor line temperature distributions. A simple axial heat transfer method is developed to predict the vapor line temperature from evaporator outlet to condenser inlet. CPL is a high efficiency two-phase heat transfer device. Since it does not need any other mechanical force such as pump, furthermore, it might be used to do the thermal management of high power electronic component such as spacecraft, notebook and computer servers. It is a cyclic circulation pumped by capillary force, and this force is generated from the fine porous structure in evaporator. A novel semi-arc porous evaporator to CPL in 1U server is designed on the ground with a horizontal position and scale down the whole device to the miniature size. From the experimental results, the CPL could remove heat 90 W in steady-state and keep the heat source temperature about 70 deg. C. Finally, a good agreement between the simulation and experimental values has been achieved. Comparing with experiment and simulation results, the deviation values of the distributions of the condenser inlet temperature are less than 8%

  15. Crystal field effect in the uranium compounds - model calculations for CsUF6, Cs2UCl6 and UCl4

    International Nuclear Information System (INIS)

    Gajek, Z.; Mulak, J.

    1987-01-01

    A practical crystal field model allowing one to estimate the crystal field parameters from first principles is presented and applied to the actinide compounds. The model results directly from the renormalization (and reduction) procedure of the true Schroedinger equation for an effective Hamiltonian acting on the 5f spin-orbitals only. In practice this approach becomes convergent with the ab initio model of Newman. Three ionic uranium compounds: CsUF 6 , Cs 2 UCl 6 and UCl 4 have served as examples of the application. The results obtained, particularly for the first two compounds, are in good agreement with the experimental data. The contributions of different mechanisms responsible for the crystal field effect are discussed. (author)

  16. Effect of Water Vapor on High-Temperature Corrosion under Conditions Mimicking Biomass Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2015-01-01

    The variable flue gas composition in biomass-fired plants, among other parameters, contributes to the complexityof high-temperature corrosion of materials. Systematic parameter studies are thus necessary to understand the underlyingcorrosion mechanisms. This paper investigates the effect of water...... (H2O) vapor content in the flue gas on the high-temperaturecorrosion of austenitic stainless steel (TP 347H FG) under laboratory conditions, to improve the understanding of corrosionmechanisms. Deposit-coated and deposit-free samples were isothermally exposed for 72 h in a synthetic flue gas...... previouslyreported findings suggest that an increase in the water vapor content will cause competitive adsorption on active sites....

  17. Release of UF6 from a ruptured model 48Y cylinder at Sequoyah Fuels Corporation Facility: lessons-learned report

    International Nuclear Information System (INIS)

    1986-08-01

    The uranium hexafluoride (UF 6 ) release of January 4, 1986, at the Sequoyah Fuels Corporation facility has been reviewed by a NRC Lessons-Learned Group. A Model 48Y cylinder containing UF 6 ruptured upon being heated after it was grossly overfilled. The UF 6 released upon rupture of the cylinder reacted with airborne moisture to produce hydrofluoric acid (HF) and uranyl fluoride (UO 2 F 2 ). One individual died from exposure to airborne HF and several others were injured. There were no significant immediate effects from exposure to uranyl fluoride. This supplement report contains NRC's response to the recommendations made in NUREG-1198 by the Lessons Learned Group. In developing a response to each of the recommendations, the staff considered actions that should be taken: (1) for the restart of the Sequoyah Fuels Facility; (2) to make near-term improvement; and (3) to improve the regulatory framework

  18. Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J. J.; Henins, A.; Hardis, J. E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Estupinan, E. G. [Osram Sylvania Inc., Beverly, Massachusetts 01915 (United States); Lapatovich, W. P. [Independent Consultant, 51 Pye Brook Lane, Boxford, Massachusetts 01921 (United States); Shastri, S. D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2012-02-20

    Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

  19. Molecular Orientation in Two Component Vapor-Deposited Glasses: Effect of Substrate Temperature and Molecular Shape

    Science.gov (United States)

    Powell, Charles; Jiang, Jing; Walters, Diane; Ediger, Mark

    Vapor-deposited glasses are widely investigated for use in organic electronics including the emitting layers of OLED devices. These materials, while macroscopically homogenous, have anisotropic packing and molecular orientation. By controlling this orientation, outcoupling efficiency can be increased by aligning the transition dipole moment of the light-emitting molecules parallel to the substrate. Light-emitting molecules are typically dispersed in a host matrix, as such, it is imperative to understand molecular orientation in two-component systems. In this study we examine two-component vapor-deposited films and the orientations of the constituent molecules using spectroscopic ellipsometry, UV-vis and IR spectroscopy. The role of temperature, composition and molecular shape as it effects molecular orientation is examined for mixtures of DSA-Ph in Alq3 and in TPD. Deposition temperature relative to the glass transition temperature of the two-component mixture is the primary controlling factor for molecular orientation. In mixtures of DSA-Ph in Alq3, the linear DSA-Ph has a horizontal orientation at low temperatures and slight vertical orientation maximized at 0.96Tg,mixture, analogous to one-component films.

  20. Testing of one-inch UF{sub 6} cylinder valves under simulated fire conditions

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, P.G. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Accurate computational models which predict the behavior of UF{sub 6} cylinders exposed to fires are required to validate existing firefighting and emergency response procedures. Since the cylinder valve is a factor in the containment provided by the UF{sub 6} cylinder, its behavior under fire conditions has been a necessary assumption in the development of such models. Consequently, test data is needed to substantiate these assumptions. Several studies cited in this document provide data related to the behavior of a 1-inch UF{sub 6} cylinder valve in fire situations. To acquire additional data, a series of tests were conducted at the Paducah Gaseous Diffusion Plant (PGDP) under a unique set of test conditions. This document describes this testing and the resulting data.

  1. The thermodynamic characteristics of vaporization of praseodymium triiodide

    Science.gov (United States)

    Motalov, V. B.; Kudin, L. S.; Markus, T.

    2009-03-01

    The vaporization of praseodymium triiodide was studied by high-temperature mass spectrometry. Monomeric (PrI3) and dimeric (Pr2I6) molecules and the PrI{4/-} and Pr2I{7/-} negative ions were recorded in saturated vapor over the temperature range 842-1048 K. The partial pressures of neutral vapor components were determined. The enthalpies of sublimation Δs H o(298.15 K) in the form of monomers (291 ± 10 kJ/mol) and dimers (400 ± 30 kJ/mol) were calculated by the second and third laws of thermodynamics. The equilibrium constants of ion-molecular reactions were measured and the enthalpies of the reactions determined. The enthalpies of formation Δf H o(298.15 K) of molecules and ions in the gas phase were calculated (-373 ± 11, -929 ± 31, -865 ± 25, and -1433 ± 48 kJ/mol for PrI3, Pr2I6, PrI{4/-}, and Pr2I{7/-}, respectively).

  2. Low temperature thermal expansion of liquid Helium-4

    International Nuclear Information System (INIS)

    Berthold, J.E.

    1976-01-01

    Results of a measurement of the thermal expansion of liquid He-4 are presented along the saturated vapor pressure curve at low temperatures (0.1 - 0.6 0 K). The thermal expansion is related to the low momentum region of the He-4 excitation spectrum, and the results of this measurement are analyzed to gain information concerning deviations from linearity in the phonon region of the spectrum. The data is also compared with theoretical predictions of Alrich and Bhatt and McMillan and with the thermal expansion measurement of Van Degrift. In addition a discussion of previous experimental evidence on the shape of the low momentum region of the dispersion relation is presented

  3. Spectroscopic properties of K{sub 5}Li{sub 2}UF{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Karbowiak, M. [Faculty of Chemistry, University of WrocIaw, ul. F. Joliot-Curie 14, 50-383 WrocIaw (Poland)]. E-mail: karb@wchuwr.chem.uni.wroc.pl; Gajek, Z. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland); Drozdzynski, J. [Faculty of Chemistry, University of WrocIaw, ul. F. Joliot-Curie 14, 50-383 WrocIaw (Poland)

    2005-04-04

    A new uranium (III) fluoro-complex of the formula K{sub 5}Li{sub 2}UF{sub 10} has been synthesised and characterised by X-ray powder diffraction and electronic absorption spectra measurements. The compound crystallises in the orthorhombic system, space group Pnma, with a = 20.723, b = 7.809, c = 6.932 A, V = 1121.89 A{sup 3}, Z = 4 and is isostructural with its K{sub 5}Li{sub 2}NdF{sub 10} and K{sub 5}Li{sub 2}LaF{sub 10} analogous. The absorption spectrum of a polycrystalline sample of K{sub 5}Li{sub 2}UF{sub 10} was recorded at 4.2 K in the 3500-45,000 cm{sup -1} range and is discussed. The observed crystal-field levels were assigned and fitted to parameters of the simplified angular overlap model (AOM) and next to those of a semi-empirical Hamiltonian, which was representing the combined atomic and one-electron crystal-field interactions. The starting values of the AOM parameters were obtained from ab initio calculations. The analysis of the spectra enabled the assignment of 71 crystal-field levels of U{sup 3+} with a relatively small r.m.s. deviation of 37 cm{sup -1}. The total splitting of 714 cm{sup -1} was calculated for the {sup 4}I{sub 9/2} ground multiplet.

  4. Lithium vapor trapping at a high-temperature lithium PFC divertor target

    Science.gov (United States)

    Jaworski, Michael; Abrams, T.; Goldston, R. J.; Kaita, R.; Stotler, D. P.; de Temmerman, G.; Scholten, J.; van den Berg, M. A.; van der Meiden, H. J.

    2014-10-01

    Liquid lithium has been proposed as a novel plasma-facing material for NSTX-U and next-step fusion devices but questions remain on the ultimate temperature limits of such a PFC during plasma bombardment. Lithium targets were exposed to high-flux plasma bombardment in the Magnum-PSI experimental device resulting in a temperature ramp from room-temperature to above 1200°C. A stable lithium vapor cloud was found to form directly in front of the target and persist to temperature above 1000°C. Consideration of mass and momentum balance in the pre-sheath region of an attached plasma indicates an increase in the magnitude of the pre-sheath potential drop with the inclusion of ionization sources as well as the inclusion of momentum loss terms. The low energy of lithium emission from a surface measured in previous experiments (Contract DE-AC02-09CH11466.

  5. Study on UF6 condensing receiving system improvement

    International Nuclear Information System (INIS)

    Zhang Zhenxing; Li Yingfeng; Li Zhenfeng; He Ping; Wang Yanping; Tian Yushan

    2012-01-01

    In order to improve receiving capacity of UF 6 condensing system, the pressure release mode is changed through modifying gas phase inlet of the first-grade condenser, thus pressure release time is reduced from 13.1 h to 8.1 h. Be- cause of improvement of utility condensers of the two product lines, both the flexibility of feeding nitrogen and the emergency capacity of condensers are improved greatly. And modification of fluid transferring and sampling system make the remains in system transfer flexibly. The practise shows that metal direct recovery rises to the extent, and capacity of the first-grade condensing receiving system improves 8.4%, which strongly guarantees fluorination production safely, continuously and stably run. (authors)

  6. Continuous Water Vapor Mass Flux and Temperature Measurements in a Model Scramjet Combustor Using a Diode Laser Sensor

    National Research Council Canada - National Science Library

    Upschulte, B. L; Miller, M. F; Allen, M. G; Jackson, K; Gruber, M; Mathur, T

    1998-01-01

    A sensor for simultaneous measurements of water vapor density, temperature and velocity has been developed based on absorption techniques using room temperature diode lasers (InGaAsP) operating at 1.31 micrometers...

  7. Review of models used for determining consequences of UF{sub 6} release: Model evaluation report. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Nair, S.K.; Chambers, D.B.; Park, S.H.; Radonjic, Z.R.; Coutts, P.T.; Lewis, C.J.; Hammonds, J.S.; Hoffman, F.O. [Senes Oak Ridge, Inc., TN (United States). Center for Risk Analysis

    1997-11-01

    Three uranium hexafluoride-(UF{sub 6}-) specific models--HGSYSTEM/UF{sub 6}, Science Application International Corporation, and RTM-96; three dense-gas models--DEGADIS, SLAB, and the Chlorine Institute methodology; and one toxic chemical model--AFTOX--are evaluated on their capabilities to simulate the chemical reactions, thermodynamics, and atmospheric dispersion of UF{sub 6} released from accidents at nuclear fuel-cycle facilities, to support Integrated Safety Analysis, Emergency Response Planning, and Post-Accident Analysis. These models are also evaluated for user-friendliness and for quality assurance and quality control features, to ensure the validity and credibility of the results. Model performance evaluations are conducted for the three UF{sub 6}-specific models, using field data on releases of UF{sub 6} and other heavy gases. Predictions from the HGSYSTEM/UF{sub 6} and SAIC models are within an order of magnitude of the field data, but the SAIC model overpredicts beyond an order of magnitude for a few UF{sub 6}-specific data points. The RTM-96 model provides overpredictions within a factor of 3 for all data points beyond 400 m from the source. For one data set, however, the RTM-96 model severely underpredicts the observations within 200 m of the source. Outputs of the models are most sensitive to the meteorological parameters at large distances from the source and to certain source-specific and meteorological parameters at distances close to the source. Specific recommendations are being made to improve the applicability and usefulness of the three models and to choose a specific model to support the intended analyses. Guidance is also provided on the choice of input parameters for initial dilution, building wake effects, and distance to completion of UF{sub 6} reaction with water.

  8. An efficient reliable method to estimate the vaporization enthalpy of pure substances according to the normal boiling temperature and critical properties

    OpenAIRE

    Mehmandoust, Babak; Sanjari, Ehsan; Vatani, Mostafa

    2014-01-01

    The heat of vaporization of a pure substance at its normal boiling temperature is a very important property in many chemical processes. In this work, a new empirical method was developed to predict vaporization enthalpy of pure substances. This equation is a function of normal boiling temperature, critical temperature, and critical pressure. The presented model is simple to use and provides an improvement over the existing equations for 452 pure substances in wide boiling range. The results s...

  9. How important are internal temperature gradients in french straws during freezing of bovine sperm in nitrogen vapor?

    Science.gov (United States)

    Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

    2013-01-01

    The subject of present work was to predict internal temperature gradients developed during freezing of bovine sperm diluted in extender, packaged in 0.5 ml French plastic straws and suspended in static liquid nitrogen vapor at -100 degree C. For this purpose, a mathematical heat transfer model previously developed to predict freezing times (phase change was considered) of semen/extender packaged in straw was extended to predict internal temperature gradients during the cooling/freezing process. Results showed maximum temperature differences between the centre and the periphery of semen/extender "liquid" column was 1.5 degree C for an external heat transfer coefficient, h = 15 W per (m(2) K), and only 0.5 degree C for h = 5 W per (m(2) K). It is concluded that if a thermocouple wire were inserted in a 0.5 ml plastic straw to monitor the freezing process in nitrogen vapor, its radial position would have little importance since expected internal gradients may be safely neglected. This finding facilitates the interpretation of freezing rates in 0.5 ml plastic straws immersed in nitrogen vapor over liquid nitrogen, a widely used method for cryopreservation of bovine spermatozoa.

  10. Study on the interaction of lithium orthosilicate with water vapor and hydrogen

    International Nuclear Information System (INIS)

    Huber, S.

    1994-09-01

    The present work discusses the adsorption of H 2 O(g) as well as the reactions of D 2 O(g) and D 2 (g) with lithium orthosilicate (Li 4 SiO 4 ), a potential tritium breeding ceramic for future fusion reactors. An apparatus was constructed which permits H 2 O partial pressures as low as 1 μbar to be generated and subsequently measured with high accuracy and precision. Using the frontal analysis of gas chromatography, adsorption isotherms were determined at temperatures and water vapor pressures ranging from 653 to 1093 K and 1 to 10 μbar, respectively. Based upon the data, the tritium inventory at the surface of Li 4 SiO 4 (cr) can be estimated as function of temperature and water vapor concentration in the purge gas of a solid breeder blanket. The reactions of lithium orthosilicate with deuterium oxide and deuterium were studied at high temperature (1160 - 1420K) by means of Knudsen effusion mass spectrometry. In both cases the production of lithium hydroxide and the establishment of an equilibrium between LiOD(g) and D 2 O(g) were observed; D 2 O is derived from oxidation of deuterium, presumably under formation of a reduced surface layer. Equilibrium constants and reaction enthalpies were computed for the reaction of Li 4 SiO 4 (cr) with D 2 O(g). In addition, the vapor pressure of LiOD(g) above Li 4 SiO 4 (cr) was determined as function of temperature and deuterium oxide pressure. Further experiments with lithium orthosilicate were carried out under flowing hydrogen in order to analyze the effects of temperature, H 2 -concentration, gas flow, sample size and sample pretreatment on the formation of water vapor. The results confirm the mass spectrometric findings mentioned above. (orig.) [de

  11. Room-temperature plasma-enhanced chemical vapor deposition of SiOCH films using tetraethoxysilane

    International Nuclear Information System (INIS)

    Yamaoka, K.; Yoshizako, Y.; Kato, H.; Tsukiyama, D.; Terai, Y.; Fujiwara, Y.

    2006-01-01

    Carbon-doped silicon oxide (SiOCH) thin films were deposited by room-temperature plasma-enhanced chemical vapor deposition (PECVD) using tetraethoxysilane (TEOS). The deposition rate and composition of the films strongly depended on radio frequency (RF) power. The films deposited at low RF power contained more CH n groups. The SiOCH films showed high etch rate and low refractive index in proportion to the carbon composition. The deposition with low plasma density and low substrate temperature is effective for SiOCH growth by PECVD using TEOS

  12. Supercritical fluid extraction-capillary gas chromatography: on-line coupling with a programmed temperature vaporizer

    NARCIS (Netherlands)

    Houben, R.J.; Janssen, J.G.M.; Leclercq, P.A.; Rijks, J.A.; Cramers, C.A.M.G.

    1990-01-01

    A simple and versatile system is described for the on-line coupling of SFE to capillary GC. The interfacing consists of a programmed temperature vaporizer (PTV) injector. With this injector it is possible to combine solute trapping, elimination of a high flow of extraction fluid, and quantitative

  13. Determination of temperature and pressure in the calcium reduction process

    International Nuclear Information System (INIS)

    Arceri, Mariana E.

    1997-01-01

    The calcium reduction process consists in the reduction of uranium tetrafluoride (UF 4 ) with calcium in a refractory material crucible, in order to obtain metallic uranium. The crucible is in turn contained in a steel reactor, heated by means of an induction coil to bring the reagents from the environmental temperature to the temperature necessary for the reaction starting. For the design of the reactor, mathematical expressions that allow to estimate the temperature and pressure of the system have been developed

  14. Ellipsometry-based combination of isothermal sorption-desorption measurement and temperature programmed desorption technique: A probe for interaction of thin polymer films with solvent vapor

    Science.gov (United States)

    Efremov, Mikhail Yu.; Nealey, Paul F.

    2018-05-01

    An environmental chamber equipped with an in situ spectroscopic ellipsometer, programmatic vapor pressure control, and variable temperature substrate holder has been designed for studying polymer coating behavior during an exposure to a solvent vapor and also for probing the residual solvent in the film afterwards. Both sorption-desorption cycle at a constant temperature and temperature programmed desorption (TPD) of the residual solvent manifest themselves as a change of the film thickness. Monitoring of ellipsometric angles of the coating allows us to determine the thickness as a function of the vapor pressure or sample temperature. The solvent vapor pressure is precisely regulated by a computer-controlled pneumatics. TPD spectra are recorded during heating of the film in an oil-free vacuum. The vapor pressure control system is described in detail. The system has been tested on 6-170 nm thick polystyrene, poly(methyl methacrylate), and poly(2-vinyl pyridine) films deposited on silicon substrates. Liquid toluene, water, ethanol, isopropanol, cyclohexane, 1,2-dichloroethane, and chlorobenzene were used to create a vapor atmosphere. Typical sorption-desorption and TPD curves are shown. The instrument achieves sub-monolayer sensitivity for adsorption studies on flat surfaces. Polymer-solvent vapor systems with strong interaction demonstrate characteristic absorption-desorption hysteresis spanning from vacuum to the glass transition pressure. Features on the TPD curves can be classified as either glass transition related film contraction or low temperature broad contraction peak. Typical absorption-desorption and TPD dependencies recorded for the 6 nm thick polystyrene film demonstrate the possibility to apply the presented technique for probing size effects in extremely thin coatings.

  15. Experimental measurements of vapor-liquid equilibria of the H2O + CO2 + CH4 ternary system

    Science.gov (United States)

    Qin, J.; Rosenbauer, R.J.; Duan, Zhenhao

    2008-01-01

    Reported are the experimental measurements on vapor-liquid equilibria in the H2O + CO2 + CH4 ternary system at temperatures from (324 to 375) K and pressures from (10 to 50) MPa. The results indicate that the CH4 solubility in the ternary mixture is about 10 % to 40 % more than that calculated by interpolation from the Henry's law constants of the binary system, H2O + CH4, and the solubility of CO2 is 6 % to 20 % more than what is calculated by the interpolation from the Henry's law constants of the binary mixture, H 2O + CO2. ?? 2008 American Chemical Society.

  16. Electronic, magnetic, transport, and thermal properties of single-crystalline UF e2A l10

    Science.gov (United States)

    Troć, R.; Samsel-Czekała, M.; Talik, E.; Wawryk, R.; Gajek, Z.; Pasturel, M.

    2015-09-01

    The valence and core-level x-ray photoemission spectra (XPS), performed on an UF e2A l10 single crystal, were measured using the Al Kα radiation. The results of valence XPS show practically two separate regions of spectral intensity, one just at the Fermi level (EF) and the other one being a wide content with its maximum at about 0.8 eV below EF. These give rise to two electronic configurations of the 5 f states in the studied aluminide, itinerant and localized ones, i.e., their dual character. In such a situation the corresponding valence spectra, calculated within the local density approximation (LDA), well explain the former configuration, being responsible for a metallic behavior of the studied compound. Moreover, this behavior is confirmed clearly also by our results of magnetotransport measurements. On the other hand, the obtained magnetic susceptibility, specific heat, electrical resistivity, and thermoelectric power data support very well the local character of the 5 f2 -electron configuration of the U4 + ion in UF e2A l10 having the orthorhombic and cage-type crystal structure. Based on that configuration, the magnetic and thermal characteristics of the compound were modeled by the effective crystal field (CF) potential in the intermediate coupling scheme using initial parameters obtained by the angular overlap model (AOM). The obtained final CF parameters yielded the CF level scheme, composed of only singlets, proper for orthorhombic symmetry. Such a set of singlets reproduces in a satisfactory way both the strongly anisotropic temperature variations of the magnetic susceptibility, measured along the three main crystallographic directions, as well as the Schottky anomaly, evaluated using specific heat results of isomorphic ThF e2A l10 as a phonon reference. Also, the strongly anisotropic behavior of the Seebeck coefficient and its low temperature maxima observed for the compound studied here have been explained roughly by the CF effect.

  17. UF{sub 6} cylinder lifting equipment enhancements

    Energy Technology Data Exchange (ETDEWEB)

    Hortel, J.M. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    This paper presents numerous enhancements that have been made to the Portsmouth lifting equipment to ensure the safe handling of cylinders containing liquid uranium hexafluoride (UF{sub 6}). The basic approach has been to provide redundancy to all components of the lift path so that any one component failure would not cause the load to drop or cause any undesirable movement.

  18. Thermal dissociation of molten KHSO4: Temperature dependence of Raman spectra and thermodynamics

    DEFF Research Database (Denmark)

    Knudsen, Christian B.; Kalampounias, Angelos G.; Fehrmann, Rasmus

    2008-01-01

    Raman spectroscopy is used to study the thermal dissociation of molten KHSO4 at temperatures of 240-450 degrees C under static equilibrium conditions. Raman spectra obtained at 10 different temperatures for the molten phase and for the vapors thereof exhibit vibrational wavenumbers and relative...... process taking place to a significant extent in the temperature range of the investigation and for determining its enthalpy to be Delta H degrees = 64.9 +/- 2.9 kJ mol(-1). The importance of these findings for the understanding of the performance of the industrially important sulfuric acid catalyst. under...

  19. Thermodynamics and Kinetics of Silicate Vaporization

    Science.gov (United States)

    Jacobson, Nathan S.; Costa, Gustavo C. C.

    2015-01-01

    Silicates are a common class of materials that are often exposed to high temperatures. The behavior of these materials needs to be understood for applications as high temperature coatings in material science as well as the constituents of lava for geological considerations. The vaporization behavior of these materials is an important aspect of their high temperature behavior and it also provides fundamental thermodynamic data. The application of Knudsen effusion mass spectrometry (KEMS) to silicates is discussed. There are several special considerations for silicates. The first is selection of an appropriate cell material, which is either nearly inert or has well-understood interactions with the silicate. The second consideration is proper measurement of the low vapor pressures. This can be circumvented by using a reducing agent to boost the vapor pressure without changing the solid composition or by working at very high temperatures. The third consideration deals with kinetic barriers to vaporization. The measurement of these barriers, as encompassed in a vaporization coefficient, is discussed. Current measured data of rare earth silicates for high temperature coating applications are discussed. In addition, data on magnesium-iron-silicates (olivine) are presented and discussed.

  20. BELINDA: Broadband Emission Lidar with Narrowband Determination of Absorption. A new concept for measuring water vapor and temperature profiles

    Science.gov (United States)

    Theopold, F. A.; Weitkamp, C.; Michaelis, W.

    1992-01-01

    We present a new concept for differential absorption lidar measurements of water vapor and temperature profiles. The idea is to use one broadband emission laser and a narrowband filter system for separation of the 'online' and 'offline' return signals. It is shown that BELINDA offers improvements as to laser emission shape and stability requirements, background suppression, and last and most important a significant reduction of the influence of Rayleigh scattering. A suitably designed system based on this concept is presented, capable of measuring water vapor or temperature profiles throughout the planetary boundary layer.

  1. [Experimental evaluation of the Sysmex UF-1000i for ruling out non-gonococcal urethritis].

    Science.gov (United States)

    Grosso, Shamanta; Bruschetta, Graziano; Camporese, Alessandro

    2012-09-01

    Acute nongonococcal urethritis (NGU) is one of the commonest sexually transmitted infections affecting men and women. The diagnosis of NGU has traditionally required microscopic evidence of urethritis. However, a significant proportion of patients with urethral symptoms do not have microscopic evidence of urethritis. The purpose of the present study was to evaluate the analytical performance of the UF1000i, a recently introduced fluorescence flow cytometer intended for urinalysis purposes which provides new analytical features that seem particularly suitable for microbiological diagnostics, for ruling out NGU or predicting the presence of infection. The Sysmex UF1000i is a flow cytometry analyzer capable of quantifying a lot of particles, including bacteria (BACT) and white blood cells (WBCs). To evaluate the analytical performance of the UF1000i as a method for ruling out NGU, we examined 200 urethral smear samples, collected in a new liquid transport medium (Copan), and compared the UF1000i results with standard culture/molecular and microscopic Gram stain results. With instrument cut-off values of 200 BACT x 10^6/L and 500 WBCs x 10^6/L, we obtained a sensitivity of 84%, a specificity of 82%, and a high negative predictive value (96%). Culture/molecular detection of pathogens remains the gold standard technique for the diagnosis of NGU. However, the Sysmex UF1000i is capable of improving the efficiency of NGU presumptive diagnosis, providing results in a few minutes, with a high negative predictive value and high values of sensitivity.

  2. Numerical simulation of vapor film collapse behavior on high-temperature droplet surface with three-dimensional lattice gas cellular automata

    International Nuclear Information System (INIS)

    Tochio, Daisuke; Abe, Yutaka; Matsukuma, Yosuke

    2008-01-01

    It is pointed out that a vapor film on a premixed high-temperature droplet surface is needed to be collapsed to trigger vapor explosion. Thus, it is important to clarify the micromechanism of vapor film collapse behavior for the occurrence of vapor explosion. In a previous study, it is suggested experimentally that vapor film collapse behavior is dominated by phase change phenomena rather than by the surrounding fluid motion. In the present study, vapor film collapse behavior is investigated to clarify the dominant factor of vapor film collapse behavior with lattice gas automata of three-dimensional immiscible lattice gas model (3-D ILG model). First, in order to represent the boiling and phase change phenomena, the thermal model of a heat wall model and a phase change model is newly constructed. Next, the numerical simulation of vapor film collapse behavior is performed with and without the phase change effect. As a result, the computational result with the phase change effect is observed to be almost same as the experimental result. It can be considered that vapor film collapse behavior is dominated by phase change phenomena. (author)

  3. Removal of hydrogen sulfide as ammonium sulfate from hydropyrolysis product vapors

    Energy Technology Data Exchange (ETDEWEB)

    Marker, Terry L.; Felix, Larry G.; Linck, Martin B.; Roberts, Michael J.

    2017-03-14

    A system and method for processing biomass into hydrocarbon fuels that includes processing a biomass in a hydropyrolysis reactor resulting in hydrocarbon fuels and a process vapor stream and cooling the process vapor stream to a condensation temperature resulting in an aqueous stream. The aqueous stream is sent to a catalytic reactor where it is oxidized to obtain a product stream containing ammonia and ammonium sulfate. A resulting cooled product vapor stream includes non-condensable process vapors comprising H.sub.2, CH.sub.4, CO, CO.sub.2, ammonia and hydrogen sulfide.

  4. Removal of hydrogen sulfide as ammonium sulfate from hydropyrolysis product vapors

    Science.gov (United States)

    Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J

    2014-10-14

    A system and method for processing biomass into hydrocarbon fuels that includes processing a biomass in a hydropyrolysis reactor resulting in hydrocarbon fuels and a process vapor stream and cooling the process vapor stream to a condensation temperature resulting in an aqueous stream. The aqueous stream is sent to a catalytic reactor where it is oxidized to obtain a product stream containing ammonia and ammonium sulfate. A resulting cooled product vapor stream includes non-condensable process vapors comprising H.sub.2, CH.sub.4, CO, CO.sub.2, ammonia and hydrogen sulfide.

  5. Research on the fundamental process of thermal-hydraulic behaviors in severe accident. Vapor film collapse behavior on high temperature particle surface. JAERI's nuclear research promotion program, H10-027-3. Contract research

    International Nuclear Information System (INIS)

    Abe, Yutaka

    2002-03-01

    The experimental researches were conducted to study vapor film collapse behavior on high temperature melted core material coarsely mixed in the coolant under the film boiling condition. The film collapse is very important incipient incident of the trigger process for the vapor explosion in sever accident of nuclear reactor. In the experiment, pressure pulse was applied to the vapor film on a high temperature particle surface simulating melted core material to observed microscopic vapor film collapse behavior with a high-speed video camera of 40,500 fps. The particle surface temperature and pressure around the particle were simultaneously measured. The transition of the vapor film thickness and two-dimensional vapor-liquid interface movement and the velocity were estimated with visual data analysis technique, PIV and digital data analysis technique. Furthermore, heat conduction analysis was performed to estimate the vapor-liquid interfacial temperature with the measured temperature and estimated vapor film thickness. As the results, it was clarified that the vapor-liquid interface changed white from transparent view for all the experimental conditions. It is also clarified that the vapor-liquid interfacial temperature decreased under the saturation temperature when the pressure pulse arrive at the particle. The experimental facts indicates the possibility that the vapor film collapse occurs due to the liquid phase homogeneous moving toward the particle drove by the pressure reduction caused by the phase change inside the vapor film. (author)

  6. The toxic and radiological risk equivalence approach in UF6 transport

    International Nuclear Information System (INIS)

    Ringot, C.; Hamard, J.

    1988-12-01

    After a brief description of the safety in transport of UF 6 , we discuss the equivalence of the radioactive and chemical risks in UF 6 transport regulations. As the concept of low specific activity appears to be ill-suited for a toxic gas, we propose a quantity of material limit designated T 2 (equivalent to A 2 for radioactive substances) for packagings unable to withstand accident conditions (9 m drop, 800 0 C fire environment for 30 minutes). It is proposed that this limit be chosen for the amount of release acceptable after AIEA tests. Different possible scenarios are described, with fire assumed to be the most severe toxic risk situation

  7. Dynamic coating of mf/uf membranes for fouling mitigation

    KAUST Repository

    Tabatabai, S. Assiyeh Alizadeh; Leiknes, TorOve

    2017-01-01

    A membrane system including an anti-fouling layer and a method of applying an anti-fouling layer to a membrane surface are provided. In an embodiment, the surface is a microfiltration (MF) or an ultrafiltration (UF) membrane surface. The anti

  8. 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.

  9. Vaporization of materials in the operation of high temperature fuel cells (SOFCs); Verdampfung von Werkstoffen beim Betrieb von Hochtemperaturbrennstoffzellen (SOFCs)

    Energy Technology Data Exchange (ETDEWEB)

    Stanislowski, M.

    2006-07-01

    One of the main problems concerning the development of state of the art planar SOFCs are the occurrence of ageing effects in long term application. To a great deal these effects are caused by the release of volatile Cr-species from metallic interconnects which leads to an inhibition of the electrochemical processes at the cathode resulting in a rapid degradation of the cell performance. A goal in further development of SOFC-systems is the reduction of the operation temperature of the cell from currently 800 C to 700 C and below. For this purpose alternative electrolyte materials with higher oxygen ion conductivities have to be developed. Doped lanthanum gallates have been identified as promising materials. However for these materials a depletion of Ga by vaporization has been observed under anodic conditions which may lead to a destruction of their electrolyte properties. The aim of this work is the study of the vaporization processes leading to the mentioned degradation effects. For this purpose an experimental setup according to the transpiration method has been developed. Concerning the vaporization of chromium the Cr release rates of the main ferritic interconnect alloys, namely Crofer 22 APU, ZMG 232, E-Brite, IT-10, IT-11, IT-14 and Ducrolloy as well as a variety of Ni- and Co-base superalloys and stainless steels with different contents of Al, Si, Ti, Mn, W, Ni and Co were measured at 800 C in air and compared to each other. The alloys that form an upper layer of Cr-Mn-spinel on top of the grown chromia scale showed a reduction of the Cr release by 61-75 % compared to pure chromia scales whereas alloys with an outer Co3O4(s) scale had a by more than 90 % reduced Cr release. For the former alloys a significant vaporization of Mn under anodic conditions could be detected. Concerning the vaporization of doped lanthanum gallates the vaporization rates of the elements Ga, Mg, Sr and La were measured as function time, temperature, gas flow rate and stoichiometry

  10. Thermal plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Heberlein, J.; Pfender, E.

    1993-01-01

    Thermal plasmas, with temperatures up to and even exceeding 10 4 K, are capable of producing high density vapor phase precursors for the deposition of relatively thick films. Although this technology is still in its infancy, it will fill the void between the relatively slow deposition processes such as physical vapor deposition and the high rate thermal spray deposition processes. In this chapter, the present state-of-the-art of this field is reviewed with emphasis on the various types of reactors proposed for this emerging technology. Only applications which attracted particular attention, namely diamond and high T c superconducting film deposition, are discussed in greater detail. (orig.)

  11. Formaldehyde emissions from ULEF- and NAF-bonded commercial hardwood plywood as influenced by temperature and relative humidity

    Science.gov (United States)

    Charles R. Frihart; James M. Wescott; Michael J. Birkeland; Kyle M. Gonner

    2010-01-01

    It is well documented in the literature that temperature and humidity can influence formaldehyde emissions from composite panels that are produced using urea-formaldehyde (UF) adhesives. This work investigates the effect of temperature and humidity on newer, ultra-low emitting formaldehyde urea formaldehyde (ULEF-UF) and no-added formaldehyde (NAF) adhesives. A...

  12. R-22 vapor explosions

    International Nuclear Information System (INIS)

    Anderson, R.P.; Armstrong, D.R.

    1977-01-01

    Previous experimental and theoretical studies of R-22 vapor explosions are reviewed. Results from two experimental investigations of vapor explosions in a medium scale R-22/water system are reported. Measurements following the drop of an unrestrained mass of R-22 into a water tank demonstrated the existence of two types of interaction behavior. Release of a constrained mass of R-22 beneath the surface of a water tank improved the visual resolution of the system thus allowing identification of two interaction mechansims: at low water temperatures, R-22/water contact would produce immediate violent boiling; at high water temperatures a vapor film formed around its R-22 as it was released, explosions were generated by a surface wave which initiated at a single location and propagated along the vapor film as a shock wave. A new vapor explosion model is proposed, it suggests explosions are the result of a sequence of three independent steps: an initial mixing phase, a trigger and growth phase, and a mature phase where a propagating shock wave accelerates the two liquids into a collapsing vapor layer causing a high velocity impact which finely fragments and intermixes the two liquids

  13. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-01-01

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 deg. C down to 450 deg. C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 Ω/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  14. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    Science.gov (United States)

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-06-01

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 °C down to 450 °C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 Ω/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  15. Conversion of U3O8 to UF6

    International Nuclear Information System (INIS)

    Bodu, R.L.

    1975-01-01

    Three main processes for the production of UF 6 from the uranium ores (yellow cake) is described. The economic aspects of the conversion - capital cost, operating costs and conversion market and the future of conversion - capacity and prices - are discussed. (HPH) [de

  16. Flashed-feed VMD configuration as a novel method for eliminating temperature polarization effect and enhancing water vapor flux

    KAUST Repository

    Alsaadi, Ahmad Salem

    2018-05-28

    The coupling of heat and mass transfer in membrane distillation (MD) process makes enhancing water vapor flux and determining MD membrane mass transfer coefficient (MTC) fairly challenging due to the development of temperature gradient near the membrane surface, referred to as temperature polarization (TP). As a result, the change in feed temperature at the membrane surface will be difficult to measure accurately. In this paper, the effect of TP was decoupled from the membrane MTC by preventing the liquid feed stream from contacting the membrane surface through the use of a novel custom-made vacuum MD (VMD) module design. Results showed that a temperature difference of 10°C between the feed bulk and feed temperatures at the membrane surface/interface is estimated to take place in the typical VMD configuration, while the proposed flashed-feed VMD configuration eliminates TP effect and gives a flux 3.5-fold higher (200kg/m2.hr) under similar operating conditions. Therefore, it can be concluded that heat transfer coefficient is considered to be the main factor controlling resistance of water vapor flux in the typical VMD configuration. The measured MTC of the tested commercial membrane was found to be more accurate and the highest among all reported MTCs in the MD literature (2.44×10−6kg/m2.s.Pa). Additionally, a transmembrane temperature difference of 5°C and 10°C in the novel configuration can produce water vapor fluxes of about 9kg/m2.hr and 40kg/m2.hr, respectively, at a feed temperature of 70°C, which is very attractive for scaling-up the process.

  17. Vapor deposition of tantalum and tantalum compounds

    International Nuclear Information System (INIS)

    Trkula, M.

    1996-01-01

    Tantalum, and many of its compounds, can be deposited as coatings with techniques ranging from pure, thermal chemical vapor deposition to pure physical vapor deposition. This review concentrates on chemical vapor deposition techniques. The paper takes a historical approach. The authors review classical, metal halide-based techniques and current techniques for tantalum chemical vapor deposition. The advantages and limitations of the techniques will be compared. The need for new lower temperature processes and hence new precursor chemicals will be examined and explained. In the last section, they add some speculation as to possible new, low-temperature precursors for tantalum chemical vapor deposition

  18. Anisotropy of the Chemical Shift Tensor for Fluorines in UF{sub 6} : Application to the Fluorine Atom Movement Model; Anisotropie du Tenseur de Deplacement Chimique des Fluors dans UF{sub 6}: Application au Modele du Mouvement des Atomes de Fluor; Anizotropiya tenzora khimicheskogo zameshcheniya ftora v UF{sub 6}. Primenenie k modeli dvizheniya atomov ftora; Anisotropia del Tensor de Desplazamiento Quimico de los Atomos de Fluor en el UF{sub 6}: Aplicacion al Modelo del Movimiento de los Atomos de Fluor

    Energy Technology Data Exchange (ETDEWEB)

    Rigny, P. [Centre d' Etudes Nucleaires de Saclay (France)

    1965-10-15

    R. Blinc et al. have made an initial study of polycrystalline uranium hexafluoride using the magnetic resonance of fluorine at 40 Mc/s. The low-temperattire spectrum (t < -20 Degree-Sign C can be analysed into a two-line superposition; this confirms the structure found by Hoard and Stroupe by X-ray investigation in which, since the UF{sub 6} octahedron has one long axis and two short axes, the fluorine atoms are divided among two different types of site. The change in the spectrum with temperature (coalescence of the two lines) suggests movement of the fluorine atoms between the two types of site. By repeating these experiments at 56.4 Mc/s and 94 Mc/s, we have been able to demonstrate the existence of considerable axial anisotropy of the chemical shift tensor (about 650 ppm). The absorption line obtained for a powder in these conditions is complex, and to study it we must envisage a line-shape function f(h), which is the probability that a grain of powder is so orientated that it resonates for the value h of the field. In the absence of movement (low-temperature spectrum) the line-shape function for each of the two lines (corresponding to the two types of site) is of the form obtained for equivalent atoms. It is known that the parameters of chemical shift tensors give information on chemical bond character. We are thus led, for example, to attribute a considerable ionic character (I Asymptotically-Equal-To 1/2) to the bonds between the uranium and the two most distant fluorine atoms. In the presence of movement the line-shape function is very different, and depends on the type of movement. For UF{sub 6}, study of the shape of the single line (t > 20 Degree-Sign C) in cases where we have anisotropy, shows that the fluorine atoms of the same molecule interchange with each other, each atom remaining in each of the positions for about 5 {mu}sec at 30 Degree-Sign C, with an activation energy of about 0.5 eV. (author) [French] Une premiere etude de l'hexafluorure d

  19. Tungsten chemical vapor deposition characteristics using SiH4 in a single wafer system

    International Nuclear Information System (INIS)

    Rosler, R.S.; Mendonca, J.; Rice, M.J. Jr.

    1988-01-01

    Several workers have recently begun using silane as a high-rate, low-temperature alternative to hydrogen for the reduction of WF 6 in the chemical vapor deposition of W. The deposition and film characteristics of both selective and blanket W using this new chemistry are explored in a radiantly heated single wafer system using closed-loop temperature control with a thermocouple in direct contact with the backside of the wafer. Selective W deposition rates of up to 1.5 μm/min were measured over the temperature range 250--550 0 C with blanket W rates typically 2--5 x lower. Resistivity is in the 10--15 μΩcm range at 300 0 C for SiH 4 /WF 6 ratios of 0.2 to 1.0, while above 400 0 C the range is 7.5--8.5 μΩcm. Si content in the W films is quite low at 10 16 to 10 17 atoms/cm 3 . Adhesion to silicon is excellent at temperatures of 350 0 C and above. Selective W using SiH 4 reduction for doped silicon contact fill shows none of the consumption or encroachment problems common to H 2 reduction, although selectivity is more sensitive. Contact resistance for p + and n + silicon contacts are comparable to aluminum controls and to previously published data. Blanket deposition into narrow geometries gives ≥0% step coverage and without keyholes in the 250--450 0 C deposition temperature range. For low-SiH 4 flows, deposition at 500 0 C causes small keyholes, while at 550 0 C even larger keyholes result. At higher SiH 4 flows, keyholes are typically not seen from 250 to 550 0 C

  20. Treatment of poultry slaughterhouse wastewater using a static granular bed reactor (SGBR) coupled with ultrafiltration (UF) membrane system.

    Science.gov (United States)

    Basitere, M; Rinquest, Z; Njoya, M; Sheldon, M S; Ntwampe, S K O

    2017-07-01

    The South African poultry industry has grown exponentially in recent years due to an increased demand for their products. As a result, poultry plants consume large volumes of high quality water to ensure that hygienically safe poultry products are produced. Furthermore, poultry industries generate high strength wastewater, which can be treated successfully at low cost using anaerobic digesters. In this study, the performance of a bench-scale mesophilic static granular bed reactor (SGBR) containing fully anaerobic granules coupled with an ultrafiltration (UF) membrane system, as a post-treatment system, was investigated. The poultry slaughterhouse wastewater was characterized by a chemical oxygen demand (COD) range between 1,223 and 9,695mg/L, average biological oxygen demand of 2,375mg/L and average fats, oil and grease (FOG) of 554mg/L. The SGBR anaerobic reactor was operated for 9 weeks at different hydraulic retention times (HRTs), i.e. 55 and 40 h, with an average organic loading rate (OLR) of 1.01 and 3.14g COD/L.day. The SGBR results showed an average COD, total suspended solids (TSS) and FOG removal of 93%, 95% and 90% respectively, for both OLR. The UF post-treatment results showed an average of COD, TSS and FOG removal of 64%, 88% and 48%, respectively. The overall COD, TSS and FOG removal of the system (SGBR and UF membrane) was 98%, 99.8%, and 92.4%, respectively. The results of the combined SGBR reactor coupled with the UF membrane showed a potential to ensure environmentally friendly treatment of poultry slaughterhouse wastewater.

  1. Alternative method of retesting UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Christ, R. [Nuclear Crago + Service GmbH, Hanau (Germany)

    1991-12-31

    The paper describes an alternative method to perform the periodic inspection of UF{sub 6} cylinders. The hydraulic test is replaced by ultrasonic checking of wall thickness and by magnetic particle testing of all the weld seams. Information about the legal background, the air leak test and the qualification of inspectors is also given.

  2. Reimiep 87. An interlaboratory U-235 enrichment determination by gamma measurement on solid UF6 sample

    International Nuclear Information System (INIS)

    Aparo, M.; Cresti, P.

    1988-01-01

    Gamma spectroscopy technique, based on the measurement of U 235 186 KeV flux, is now currently used for the determination of Uranium enrichment in different material of nuclear fuel cycle, namely: Uranium metallic, UO 2 pellets, UF 6 liquid or solid. The present paper describes the use of such a technique and the obtained results in determining the U 235 /U atomic isotopic abundance on a certified UF 6 solid sample. The measurements have been carried out in the frame work of the partecipation to the ''UF 6 Interlaboratory Measurements Evaluation Programme'' organized by CBNM/Geel with the support of the ESARDA (European Safeguards Research and Development Association)

  3. Treatment of car wash wastewater by UF membranes

    Science.gov (United States)

    Istirokhatun, Titik; Destianti, Puti; Hargianintya, Adenira; Oktiawan, Wiharyanto; Susanto, Heru

    2015-12-01

    The existence of car wash service facilitates car owners to remove dirt and grime from their vehicles. However, the dirt washed off vehicles as well as the cleaning materials themselves may be harmful to the environment if they are not properly managed and discharged. Many technologies have been proposed to treat car wash wastewater such as coagulation flocculation, tricking filter and flocculation-flotation. Nevertheless, these technologies have low efficiency to eliminate oil and small organic compounds. Ultrafiltration (UF) membranes were used in this study to treat car wash wastewater. This study investigated the performance of UF membranes under various pressures to remove COD, oil and grease, and also turbidity from car wash waste water. The membrane performance was examined by investigation of permeate flux and membrane rejection. The results meet the standard of environmental regulation and it is possible to be reused. The highest rejection was shown by PES10 (polyethersulfone 10 kDa) in 1 bar operation with complete rejection for both turbidity and oil and grace and 95% rejection for COD.

  4. An efficient reliable method to estimate the vaporization enthalpy of pure substances according to the normal boiling temperature and critical properties.

    Science.gov (United States)

    Mehmandoust, Babak; Sanjari, Ehsan; Vatani, Mostafa

    2014-03-01

    The heat of vaporization of a pure substance at its normal boiling temperature is a very important property in many chemical processes. In this work, a new empirical method was developed to predict vaporization enthalpy of pure substances. This equation is a function of normal boiling temperature, critical temperature, and critical pressure. The presented model is simple to use and provides an improvement over the existing equations for 452 pure substances in wide boiling range. The results showed that the proposed correlation is more accurate than the literature methods for pure substances in a wide boiling range (20.3-722 K).

  5. A Simple Experiment for Determining Vapor Pressure and Enthalpy of Vaporization of Water.

    Science.gov (United States)

    Levinson, Gerald S.

    1982-01-01

    Laboratory procedures, calculations, and sample results are described for a freshman chemistry experiment in which the Clausius-Clapeyron equation is introduced as a means of describing the variation of vapor pressure with temperature and for determining enthalpy of vaporization. (Author/SK)

  6. Metals, heavy metals and microorganism removal from spent filter backwash water by hybrid coagulation-UF processes

    Directory of Open Access Journals (Sweden)

    Mokhtar Mahdavi

    2018-04-01

    Full Text Available Spent filter backwash water (SFBW reuse has attracted particular attention, especially in countries that experience water scarcity. It can act as a permanent water source until the water treatment plant is working. In this study, the concentrations of Fe, Al, Pb, As, and Cd with total and fecal coliform (TC/FC were investigated in raw and treated SFBW by hybrid coagulation-UF processes. The pilot plant consisted of pre-sedimentation, coagulation, flocculation, clarification, and ultrafiltration (UF units. Poly-aluminum ferric chloride (PAFCL and ferric chloride (FeCl3 were used as pretreatment. The results showed that, at the optimum dose of PAFCl, the average removal of TC and FC was 88 and 79% and with PAFCl-UF process, it reached 100 and 100%, respectively. For FeCl3, removal efficiency of TC and FC were 81 and 72% and by applying FeCl3-UF process, it reached 100 and 100%, respectively. In comparison with FeCl3, PAFCl showed better removal efficiency for Fe, Pb, As, and Cd, except residual Al concentration. Coagulation-UF process could treat SFBW efficiently and treated SFBW could meet the US-EPA drinking water standard. Health risk index values of Fe, AL, Pb, AS, and Cd in treated SFBW indicate no risk of exposure to the use of this water.

  7. Temporary patching of damaged UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, A.L. [Martin Marietta Energy Systems, Inc., OH (United States)

    1991-12-31

    Patching techniques based on application of epoxy resins have been developed for temporarily repairing UF{sub 6} cylinders which have sustained relatively minor damage and must be safely emptied. The method is considerably faster and simpler than metallurgical weld repairs. Laboratory tests, detailed operational procedures, and case histories of experience at the Portsmouth Gaseous Diffusion Plant are described.

  8. MODIS/Aqua Temperature and Water Vapor Profiles 5-Min L2 Swath 5km V006

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS/Aqua Temperature and Water Vapor Profiles 5-Min L2 Swath 5km (MYD07_L2). MODIS was launched aboard the Aqua satellite on May 04, 2002 (1:30 pm equator crossing...

  9. Electrically Cooled Germanium System for Measurements of Uranium Enrichments in UF6 Cylinders

    International Nuclear Information System (INIS)

    Dvornyak, P.; Koestlbauer, M.; Lebrun, A.; Murray, M.; Nizhnik, V.; Saidler, C.; Twomey, T.

    2010-01-01

    Measurements of Uranium enrichment in UF6 cylinders is a significant part of the IAEA Safeguards verification activities at enrichment and conversion plants. Nowadays, one of the main tools for verification of Uranium enrichment in UF6 cylinders used by Safeguards inspectors is the gamma spectroscopy system with HPGe detector cooled with liquid nitrogen. Electrically Cooled Germanium System (ECGS) is a new compact and portable high resolution gamma spectrometric system free from liquid nitrogen cooling, which can be used for the same safeguards applications. It consists of the ORTEC Micro-trans-SPEC HPGe Portable Spectrometer, a special tungsten collimator and UF6 enrichment measurement software. The enrichment of uranium is determined by of quantifying the area of the 185.7 keV peak provided that the measurement is performed with a detector viewing an infinite thickness of material. Prior starting the verification of uranium enrichment at the facility, the ECGS has to be calibrated with a sample of known uranium enrichment, material matrix, container wall thickness and container material. Evaluation of the ECGS capabilities was performed by carrying out a field test on actual enrichment verification of uranium in UF6 cylinder or other forms of uranium under infinite thickness conditions. The results of these evaluations allow to say that the use of ECGS will enhance practicality of the enrichment measurements and support unannounced inspection activities at enrichment and conversion plants. (author)

  10. Predicting the heat of vaporization of iron at high temperatures using time-resolved laser-induced incandescence and Bayesian model selection

    Science.gov (United States)

    Sipkens, Timothy A.; Hadwin, Paul J.; Grauer, Samuel J.; Daun, Kyle J.

    2018-03-01

    Competing theories have been proposed to account for how the latent heat of vaporization of liquid iron varies with temperature, but experimental confirmation remains elusive, particularly at high temperatures. We propose time-resolved laser-induced incandescence measurements on iron nanoparticles combined with Bayesian model plausibility, as a novel method for evaluating these relationships. Our approach scores the explanatory power of candidate models, accounting for parameter uncertainty, model complexity, measurement noise, and goodness-of-fit. The approach is first validated with simulated data and then applied to experimental data for iron nanoparticles in argon. Our results justify the use of Román's equation to account for the temperature dependence of the latent heat of vaporization of liquid iron.

  11. 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

  12. Research on the fundamental process of thermal-hydraulic behaviors in severe accident. Vapor film collapse behavior on high temperature particle surface. JAERI's nuclear research promotion program, H10-027-3. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Yutaka [Tsukuba Univ., Institute of Engineering Mechanics and Systems, Tsukuba, Ibaraki (Japan)

    2002-03-01

    The experimental researches were conducted to study vapor film collapse behavior on high temperature melted core material coarsely mixed in the coolant under the film boiling condition. The film collapse is very important incipient incident of the trigger process for the vapor explosion in sever accident of nuclear reactor. In the experiment, pressure pulse was applied to the vapor film on a high temperature particle surface simulating melted core material to observed microscopic vapor film collapse behavior with a high-speed video camera of 40,500 fps. The particle surface temperature and pressure around the particle were simultaneously measured. The transition of the vapor film thickness and two-dimensional vapor-liquid interface movement and the velocity were estimated with visual data analysis technique, PIV and digital data analysis technique. Furthermore, heat conduction analysis was performed to estimate the vapor-liquid interfacial temperature with the measured temperature and estimated vapor film thickness. As the results, it was clarified that the vapor-liquid interface changed white from transparent view for all the experimental conditions. It is also clarified that the vapor-liquid interfacial temperature decreased under the saturation temperature when the pressure pulse arrive at the particle. The experimental facts indicates the possibility that the vapor film collapse occurs due to the liquid phase homogeneous moving toward the particle drove by the pressure reduction caused by the phase change inside the vapor film. (author)

  13. Presentation and interpretation of field experiments of gaseous UF6 releases in the atmosphere

    International Nuclear Information System (INIS)

    Crabol, B.; Boulaud, D.; Deville-Cavelin, G.

    1992-01-01

    An experimental programme concerning the behaviour of UF 6 released in gaseous phase in the atmosphere has been conducted in the years 1986-1989 by the french Atomic Energy Commission and Eurodif. Three field tests have been performed on the CEA/CESTA experimental site. These experiments permitted to get informations about the kinetics of the hydrolysis reaction of the UF 6 , the behaviour of the hydrolysis products in the atmosphere and the granulometry of the solid particles

  14. Presentation and interpretation of field experiments of gaseous UF6 releases in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Crabol, B.; Boulaud, D.; Deville-Cavelin, G. [CEA Centre d`Etudes de Fontenay-aux-Roses, 92 (France). Dept. de Protection de l`Environnement et des Installations; Geisse, C.; Iacona, L. [EURODIF, 26 - Pierrelatte (France)

    1992-12-31

    An experimental programme concerning the behaviour of UF{sub 6} released in gaseous phase in the atmosphere has been conducted in the years 1986-1989 by the french Atomic Energy Commission and Eurodif. Three field tests have been performed on the CEA/CESTA experimental site. These experiments permitted to get informations about the kinetics of the hydrolysis reaction of the UF{sub 6}, the behaviour of the hydrolysis products in the atmosphere and the granulometry of the solid particles.

  15. Fouling Removal of UF Membrane with Coated TiO2 Nanoparticles under UV Irradiation for Effluent Recovery during TFT-LCD Manufacturing

    Directory of Open Access Journals (Sweden)

    S. H. You

    2013-01-01

    Full Text Available An ultrafiltration (UF membrane process was employed to treat the secondary effluent discharged from a manufacturing of thin film transistor-liquid crystal display (TFT-LCD in this study. A bench-scale system was performed to evaluate the fouling removal of a UF membrane with coated titanium dioxide (TiO2 nanoparticles under UV irradiation. The operating pressure and feed temperature were controlled at 300 KN/m2 and 25°C, respectively. It was found that the optimum operating conditions were attained with TiO2 concentrations of 10 wt% for both 5 KD and 10 KD MWCO. Continuous UV irradiation of 5 KD MWCO improved the permeate flux rate from 45.0% to 59.5% after 4 hours of operation. SEM-EDS analysis also showed that the photocatalytic effect had reduced the average thickness of cake fouling on the membrane from 6.40 μm to 2.70 μm for 5 KD MWCO and from 6.70 μm to 3.1 μm for 10 KD MWCO. In addition, the membrane contact angle was reduced from 54° to 44°. The photocatalytic properties of TiO2 apparently increased the hydrophilicity of the membrane surface, thereby reducing membrane fouling.

  16. Vapor generation methods for explosives detection research

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2012-12-01

    The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

  17. Experimental study of lactose hydrolysis and separation in cstr-uf membrane reactor

    Directory of Open Access Journals (Sweden)

    M. Namvar-Mahboub

    2012-09-01

    Full Text Available In this study, the effect of processing conditions on the performance of continuous stirred tank -ultrafiltration (CSTR-UF in dead - end mode was investigated. An UF membrane with a molecular weight cutoff of 3 kDa made of regenerated cellulose material was used to separate enzyme from products. The effect of operating pressure ranging between 2 and 5 bar and time on the performance of the CSTR-UF system was studied. The experiments were performed with a 0.139 molar aqueous solution of lactose as feed. According to the experimental data, the lactose concentration in the permeate decreased with time due to concentration polarization and hydrolysis. It was found that the rejection factor of lactose increases from 33 to 77% with time from 5 to 85 min. Permeation flux of the membrane was evaluated in terms of pure water flux (PWF and lactose aqueous solution. Results showed that a high operating pressure led to a high permeation flux for both mentioned cases. Also, adding lactose and enzyme to pure water caused a reduction of the permeation flux due to concentration polarization.

  18. Reduced water vapor transmission rates of low-temperature solution-processed metal oxide barrier films via ultraviolet annealing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seonuk; Jeong, Yong Jin; Baek, Yonghwa; Kim, Lae Ho; Jang, Jin Hyuk; Kim, Yebyeol [POSTECH Organic Electronics Laboratory, Polymer Research Institute, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of); An, Tae Kyu [Department of Polymer Science & Engineering, Korea National University of Transportation, 50 Daehak-Ro, Chungju (Korea, Republic of); Nam, Sooji, E-mail: sjnam15@etri.re.kr [Information Control Device Section, Electronics and Telecommunications Research Institute, Daejeon, 305-700 (Korea, Republic of); Kim, Se Hyun, E-mail: shkim97@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, North Gyeongsang 712-749 (Korea, Republic of); Jang, Jaeyoung, E-mail: jyjang15@hanyang.ac.kr [Department of Energy Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Park, Chan Eon, E-mail: cep@postech.ac.kr [POSTECH Organic Electronics Laboratory, Polymer Research Institute, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2017-08-31

    Highlights: • Sol-gel-derived aluminum oxide thin films were prepared using ultraviolet (UV) annealing. • UV irradiation dramatically promoted the densification of AlO{sub x} during the annealing stage, thereby forming a close-packed AlO{sub x} film. • The resulting AlO{sub x} films deposited on polymer substrates exhibited good water vapor blocking properties with low water vapor transmission rates (WVTRs). - Abstract: Here, we report the fabrication of low-temperature sol-gel-derived aluminum oxide (AlO{sub x}) films via ultraviolet (UV) annealing and the investigation of their water vapor blocking properties by measuring the water vapor transmission rates (WVTRs). The UV annealing process induced the formation of a dense metal-oxygen-metal bond (Al-O-Al structure) at low temperatures (<200 °C) that are compatible with commercial plastic substrates. The density of the UV-annealed AlO{sub x} thin film at 180 °C was comparable to that of AlO{sub x} thin films that have been thermally annealed at 350 °C. Furthermore, the UV-annealed AlO{sub x} thin films exhibited a high optical transparency in the visible region (>99%) and good electrical insulating properties (∼10{sup −7} A/cm{sup 2} at 2 MV/cm). Finally, we confirmed that a dense AlO{sub x} thin film was successfully deposited onto the plastic substrate via UV annealing at low temperatures, leading to a substantial reduction in the WVTRs. The Ca corrosion test was used to measure the WVTRs of AlO{sub x} thin films deposited onto polyethylene naphthalate or polyimide substrates, determined to be 0.0095 g m{sup −2} day{sup −1} (25 °C, 50% relative humidity) and 0.26 g m{sup −2} day{sup −1}, respectively.

  19. Release of UF6 from a ruptured Model 48Y cylinder at Sequoyah Fuels Corporation Facility: lessons-learned report

    International Nuclear Information System (INIS)

    1986-06-01

    The uranium hexafluoride (UF 6 ) release of January 4, 1986, at the Sequoyah Fuels Corporation facility has been reviewed by a NRC Lessons-Learned Group. A Model 48Y cylinder containing UF 6 ruptured upon being heated after it was grossly overfilled. The Uf 6 released upon rupture of the cylinder reacted with airborne moisture to produce hydrofluoric acid (HF) and uranyl fluoride (UO 2 F 2 ). One individual died from exposure to airborne HF and several others were injured. There were no significant immediate effects from exposure to uranyl fluoride. This report of the Lessons-Learned Group presents discussions and recommendations on the process, operation and design of the facility, as well as on the responses of the licensee, NRC, and other local, state and federal agencies to the incident. It also provides recommendations in the areas of NRC licensing and inspection of fuel facility and certain other NMSS licensees. The implementation of some recommendations will depend on decisions to be made regarding the scope of NRC responsibilities with respect to those aspects of the design and operation of such facilities that are not directly related to radiological safety

  20. An efficient reliable method to estimate the vaporization enthalpy of pure substances according to the normal boiling temperature and critical properties

    Directory of Open Access Journals (Sweden)

    Babak Mehmandoust

    2014-03-01

    Full Text Available The heat of vaporization of a pure substance at its normal boiling temperature is a very important property in many chemical processes. In this work, a new empirical method was developed to predict vaporization enthalpy of pure substances. This equation is a function of normal boiling temperature, critical temperature, and critical pressure. The presented model is simple to use and provides an improvement over the existing equations for 452 pure substances in wide boiling range. The results showed that the proposed correlation is more accurate than the literature methods for pure substances in a wide boiling range (20.3–722 K.

  1. Formaldehyde Emissions from Urea-Formaldehyde- and no-added-formaldehyde-Bonded particleboard as Influenced by Temperature and Relative Humidity

    Science.gov (United States)

    Charles R. Frihart; James M. Wescott; Timothy L. Chaffee; Kyle M. Gonner

    2012-01-01

    It is well documented that temperature and humidity can influence formaldehyde emissions from composite panels that are produced using urea-formaldehyde (UF)–type adhesives. This work investigates the effect of temperature and humidity on newer commercial California Air Resources Board (CARB) phase II–compliant particleboard produced with UF-type adhesives. These...

  2. Removal of uranium and thorium from aqueous solution by ultrafiltration (UF) and PAMAM dendrimer assisted ultrafiltration (DAUF)

    International Nuclear Information System (INIS)

    Ilaiyaraja, P.; Ashish Kumar Singha Deb; Ponraju, D.

    2015-01-01

    Studies on removal of U(VI) and Th(IV) from aqueous solution have been carried out by ultrafiltration (UF) and dendrimer assisted ultrafiltration (DAUF) using regenerated cellulose acetate membrane and PAMAM [poly(amido)amine] dendrimer chelating agent. In UF, the U(VI) and Th(IV) are removed from aqueous solution by adsorption/mass deposition on the membrane at pH > 4. In DAUF, the water soluble PAMAM dendrimer chelating agent effectively concentrates these metal ions in retentate thereby preventing the mass deposition on membrane. At acidic pH (≤3), the binding of metal ions with PAMAM dendrimer is very weak and hence PAMAM can be regenerated and reused. Electronic supplementary material. The online version of this article (doi:10.1007/s10967-014-3462-x) contains supplementary material, which is available to authorized users. (author)

  3. Uniform deposition of uranium hexafluoride (UF6): Standardized mass deposits and controlled isotopic ratios using a thermal fluorination method

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, Bruce K.; O’Hara, Matthew J.; Casella, Andrew M.; Carter, Jennifer C.; Addleman, R. Shane; MacFarlan, Paul J.

    2016-07-01

    Abstract: We report a convenient method for the generation of volatile uranium hexafluoride (UF6) from solid uranium oxides and other uranium compounds, followed by uniform deposition of low levels of UF6 onto sampling coupons. Under laminar flow conditions, UF6 is shown to interact with surfaces within the chamber to a highly predictable degree. We demonstrate the preparation of uranium deposits that range between ~0.01 and 470±34 ng∙cm-2. The data suggest the method can be extended to creating depositions at the sub-picogram∙cm-2 level. Additionally, the isotopic composition of the deposits can be customized by selection of the uranium source materials. We demonstrate a layering technique whereby two uranium solids, each with a different isotopic composition, are employed to form successive layers of UF6 on a surface. The result is an ultra-thin deposit of UF6 that bears an isotopic signature that is a composite of the two uranium sources. The reported deposition method has direct application to the development of unique analytical standards for nuclear safeguards and forensics.

  4. Avslag på uførepensjon

    Directory of Open Access Journals (Sweden)

    Anders M. Galaasen

    2010-01-01

    Full Text Available Introduksjon: Mens mye er skrevet om hvem som får uførepensjon, foreligger det få vitenskapelige artikler om avslag på søknad om uførepensjon.Mål: Vi har gjennomført en undersøkelse over hvem som får avslag på søknad om uførepensjon og hvorledes det går med dem i en 6-7 års oppfølging.Metoder: Data fra FD-trygd, koplet med Statistisk sentralbyrås demografiske data er brukt for å sammenlikne dem som får avslag med dem som blir innvilget uførepensjon 1993 ut fra alder, kjønn, utdanning, etnisitet og inntekt. Trygdestatus for dem med avslag er så fulgt til 2000.Resultater: Vi har funnet at kvinner oftere får avslag enn menn, at de eldste og yngste sjeldnere får avslag og at de med minst inntekt og ikke-vestlig bakgrunn oftere får avslag, mens avslagsprosenten er omtrent den samme på alle utdanningsnivåer. I en oppfølging frem til 2000 viser det seg at de fleste ender opp med trygdeytelser, og at kjønnsforskjellene ytterligere forsterkes. De få av de yngste som får avslag, er relativt hyppig fortsatt uten ytelser.Konklusjon: Selv om noen av dem som får avslag, klarer å komme tilbake til normalt lønnsarbeid, og derigjennom bidra til økt produktivitet, resulterer avslag oftere kun i en utsettelse av overgang til permanente trygdeytelser. Hva den eventuelle samfunnsøkonomiske gevinsten av en slik utsettelse er, når man også tar i betraktning økt saksbehandling fra NAV, samt utgifter til attføring og rehabilitering, er et spørsmål for videre forskning. Galaasen AM, Bruusgaard D, Claussen B. Denial of disability pension. Nor J Epidemiol 2009; 19 (2: 203-208. ENGLISH SUMMARYIntroduction: While much is written about who gets disability pensions, there are few scientific articles on the denial of disability pension.Objective: We conducted a survey of who is rejected disability pension and how their life situation evolves in a 6- 7-year follow-up.Methods: Data from FD-trygd, coupled with Statistics Norway

  5. Detection of water vapor on Jupiter

    Science.gov (United States)

    Larson, H. P.; Fink, U.; Treffers, R.; Gautier, T. N., III

    1975-01-01

    High-altitude (12.4 km) spectroscopic observations of Jupiter at 5 microns from the NASA 91.5 cm airborne infrared telescope have revealed 14 absorptions assigned to the rotation-vibration spectrum of water vapor. Preliminary analysis indicates a mixing ratio about 1 millionth for the vapor phase of water. Estimates of temperature (greater than about 300 K) and pressure (less than 20 atm) suggest observation of water deep in Jupiter's hot spots responsible for its 5 micron flux. Model-atmosphere calculations based on radiative-transfer theory may change these initial estimates and provide a better physical picture of Jupiter's atmosphere below the visible cloud tops.

  6. Low-Temperature Process for Atomic Layer Chemical Vapor Deposition of an Al2O3 Passivation Layer for Organic Photovoltaic Cells.

    Science.gov (United States)

    Kim, Hoonbae; Lee, Jihye; Sohn, Sunyoung; Jung, Donggeun

    2016-05-01

    Flexible organic photovoltaic (OPV) cells have drawn extensive attention due to their light weight, cost efficiency, portability, and so on. However, OPV cells degrade quickly due to organic damage by water vapor or oxygen penetration when the devices are driven in the atmosphere without a passivation layer. In order to prevent damage due to water vapor or oxygen permeation into the devices, passivation layers have been introduced through methods such as sputtering, plasma enhanced chemical vapor deposition, and atomic layer chemical vapor deposition (ALCVD). In this work, the structural and chemical properties of Al2O3 films, deposited via ALCVD at relatively low temperatures of 109 degrees C, 200 degrees C, and 300 degrees C, are analyzed. In our experiment, trimethylaluminum (TMA) and H2O were used as precursors for Al2O3 film deposition via ALCVD. All of the Al2O3 films showed very smooth, featureless surfaces without notable defects. However, we found that the plastic flexible substrate of an OPV device passivated with 300 degrees C deposition temperature was partially bended and melted, indicating that passivation layers for OPV cells on plastic flexible substrates need to be formed at temperatures lower than 300 degrees C. The OPV cells on plastic flexible substrates were passivated by the Al2O3 film deposited at the temperature of 109 degrees C. Thereafter, the photovoltaic properties of passivated OPV cells were investigated as a function of exposure time under the atmosphere.

  7. Synthesis and analysis of silicon nanowire below Si-Au eutectic temperatures using very high frequency plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Hamidinezhad, Habib; Wahab, Yussof; Othaman, Zulkafli; Ismail, Abd Khamim

    2011-01-01

    Silicon nanowires (SiNWs) were synthesized from pure silane precursor gas and Au nanoparticles catalyst at below Au-Si eutectic temperature. The SiNWs were grown onto Si (1 1 1) substrates using very high frequency plasma enhanced chemical vapor deposition via a vapor-solid-solid mechanism at temperatures ranging from 363 to 230 deg. C. The morphology of the synthesized SiNWs was characterized by means of field emission scanning electron microscope equipped with energy dispersive X-ray, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscope. Results demonstrated that the SiNWs can be grown at the temperature as low as 250 deg. C. In addition, it was revealed that the grown wires were silicon-crystallized.

  8. Collapsing criteria for vapor film around solid spheres as a fundamental stage leading to vapor explosion

    Energy Technology Data Exchange (ETDEWEB)

    Freud, Roy [Nuclear Research Center - Negev, Beer-Sheva (Israel)], E-mail: freud@bgu.ac.il; Harari, Ronen [Nuclear Research Center - Negev, Beer-Sheva (Israel); Sher, Eran [Pearlstone Center for Aeronautical Studies, Department of Mechanical Engineering, Ben-Gurion University, Beer-Sheva (Israel)

    2009-04-15

    Following a partial fuel-melting accident, a Fuel-Coolant Interaction (FCI) can result with the fragmentation of the melt into tiny droplets. A vapor film is then formed between the melt fragments and the coolant, while preventing a contact between them. Triggering, propagation and expansion typically follow the premixing stage. In the triggering stage, vapor film collapse around one or several of the fragments occurs. This collapse can be the result of fragments cooling, a sort of mechanical force, or by any other means. When the vapor film collapses and the coolant re-establishes contact with the dry surface of the hot melt, it may lead to a very rapid and rather violent boiling. In the propagation stage the shock wave front leads to stripping of the films surrounding adjacent droplets which enhance the fragmentation and the process escalates. During this process a large quantity of liquid vaporizes and its expansion can result in destructive mechanical damage to the surrounding structures. This multiphase thermal detonation in which high pressure shock wave is formed is regarded as 'vapor explosion'. The film boiling and its possible collapse is a fundamental stage leading to vapor explosion. If the interaction of the melt and the coolant does not result in a film boiling, no explosion occurs. Many studies have been devoted to determine the minimum temperature and heat flux that is required to maintain a film boiling. The present experimental study examines the minimum temperature that is required to maintain a film boiling around metal spheres immersed into a liquid (subcooled distilled water) reservoir. In order to simulate fuel fragments that are small in dimension and has mirror-like surface, small spheres coated with anti-oxidation layer were used. The heat flux from the spheres was calculated from the sphere's temperature profiles and the sphere's properties. The vapor film collapse was associated with a sharp rise of the heat flux

  9. Collapsing criteria for vapor film around solid spheres as a fundamental stage leading to vapor explosion

    International Nuclear Information System (INIS)

    Freud, Roy; Harari, Ronen; Sher, Eran

    2009-01-01

    Following a partial fuel-melting accident, a Fuel-Coolant Interaction (FCI) can result with the fragmentation of the melt into tiny droplets. A vapor film is then formed between the melt fragments and the coolant, while preventing a contact between them. Triggering, propagation and expansion typically follow the premixing stage. In the triggering stage, vapor film collapse around one or several of the fragments occurs. This collapse can be the result of fragments cooling, a sort of mechanical force, or by any other means. When the vapor film collapses and the coolant re-establishes contact with the dry surface of the hot melt, it may lead to a very rapid and rather violent boiling. In the propagation stage the shock wave front leads to stripping of the films surrounding adjacent droplets which enhance the fragmentation and the process escalates. During this process a large quantity of liquid vaporizes and its expansion can result in destructive mechanical damage to the surrounding structures. This multiphase thermal detonation in which high pressure shock wave is formed is regarded as 'vapor explosion'. The film boiling and its possible collapse is a fundamental stage leading to vapor explosion. If the interaction of the melt and the coolant does not result in a film boiling, no explosion occurs. Many studies have been devoted to determine the minimum temperature and heat flux that is required to maintain a film boiling. The present experimental study examines the minimum temperature that is required to maintain a film boiling around metal spheres immersed into a liquid (subcooled distilled water) reservoir. In order to simulate fuel fragments that are small in dimension and has mirror-like surface, small spheres coated with anti-oxidation layer were used. The heat flux from the spheres was calculated from the sphere's temperature profiles and the sphere's properties. The vapor film collapse was associated with a sharp rise of the heat flux during the cooling

  10. Thermal characteristics of high-temperature R718 heat pumps with turbo compressor thermal vapor recompression

    International Nuclear Information System (INIS)

    Šarevski, Milan N.; Šarevski, Vasko N.

    2017-01-01

    Highlights: • High pressure ratio, high speed, transonic R718 centrifugal compressors. • High efficient industrial evaporators/concentrators with turbo thermal vapor recompression. • Utilization of waste heat from industrial thermal and processing systems. • R718 is an ideal refrigerant for the novel high-temperature industrial heat pumps. • Application of single-stage R718 centrifugal compressors. - Abstract: Characteristics of R718 centrifugal compressors are analyzed and range of their applications in industrial high-temperature heat pumps, district heating systems and geothermal green house heating systems are estimated. Implementation of turbo compressor thermal vapor recompression in industrial evaporating/concentrating plants for waste heat utilization results in a high energy efficiency and in other technical, economical and environmental benefits. A novel concept of turbo compression R718 heat pumps is proposed and an assessment of their thermal characteristics is presented for utilization of waste heat from industrial thermal plants and systems (boilers, furnaces, various technological and metallurgical cooling processes, etc.), and for applications in district heating and geothermal green house heating systems. R718 is an ideal refrigerant for the novel high-temperature turbo compression industrial heat pumps. Direct evaporation and condensation are advantages of the proposed system which lead to higher COP, and to simplification of the plant and lower cost.

  11. Theoretical study of relativistic effects in the electronic structure and chemical bonding of UF6

    International Nuclear Information System (INIS)

    Onoe, Jun; Takeuchi, Kazuo; Sekine, Rika; Nakamatsu, Hirohide; Mukoyama, Takeshi; Adachi, Hirohiko.

    1992-01-01

    We have performed the relativistic molecular orbital calculation for the ground state of UF 6 , using the discrete-variational Dirac-Slater method (DV-DS), in order to elucidate the relativistic effects in the electronic structure and chemical bonding. Compared with the electronic structure calculated by the non-relativistic Hartree-Fock-Slater (DV-X α )MO method, not only the direct relativistic effects (spin-orbit splitting etc), but also the indirect effect due to the change in screening core potential charge are shown to be important in the MO level structure. From the U-F bond overlap population analysis, we found that the U-F bond formation can be explained only by the DV-DS, not by the DV-X α . The calculated electronic structure in valence energy region (-20-OeV) and excitation energies in UV region are in agreement with experiments. (author)

  12. 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.

  13. Refueling emissions from cars in Japan: Compositions, temperature dependence and effect of vapor liquefied collection system

    Science.gov (United States)

    Yamada, Hiroyuki; Inomata, Satoshi; Tanimoto, Hiroshi

    2015-11-01

    Refueling emissions from cars available on the Japanese market, which were not equipped with specific controlling devices, were investigated. For the composition analysis, a proton transfer reaction plus switchable reagent ion mass spectrometry (PTR + SRI-MS), which is capable of real-time measurement, was used. In addition, the performance of a vapor liquefied collection system (VLCS), which is a recently developed controlling device, was evaluated and compared with an onboard refueling vapor recovery (ORVR) system. The refueling emission factor of uncontrolled vehicles at 20 °C was 1.02 ± 0.40 g/L in the case dispensing 20 L of fuel. The results of composition analysis indicated that the maximum incremental reactivity (MIR) of refueling emissions in Japan was 3.49 ± 0.83. The emissions consist of 80% alkanes and 20% alkenes, and aromatics and di-enes were negligible. C4 alkene had the highest impact on the MIR of refueling emissions. The amounts of refueling emissions were well reproduced by a function developed by MOVE2010 in the temperature range of 5-35 °C. The compositions of the refueling emissions varied in this temperature range, but the change in MIR was negligible. The trapping efficiency of VLCS was the same level as that of the ORVR (over 95%). The MIRs of refueling and evaporative emissions were strongly affected by that of the test fuel. This study and our previous study indicated that MIRbreakthrough ≈ MIRrefueling ≈ MIRfuel + 0.5 and MIRpermeation ≈ MIRfuel. The real-world estimated average MIRfuel in Japan was about 3.0.

  14. On Line Enrichment Monitor (OLEM) UF6 Tests for 1.5" Sch40 SS Pipe, Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    March-Leuba, José A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Garner, Jim [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Younkin, Jim [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Simmons, Darrell W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-01-01

    As global uranium enrichment capacity under international safeguards expands, the International Atomic Energy Agency (IAEA) is challenged to develop effective safeguards approaches at gaseous centrifuge enrichment plants while working within budgetary constraints. The “Model Safeguards Approach for Gas Centrifuge Enrichment Plants” (GCEPs) developed by the IAEA Division of Concepts and Planning in June 2006, defines the three primary Safeguards objectives to be the timely detection of: 1) diversion of significant quantities of natural (NU), depleted (DU) or low-enriched uranium (LEU) from declared plant flow, 2) facility misuse to produce undeclared LEU product from undeclared feed, and 3) facility misuse to produce enrichments higher than the declared maximum, in particular, highly enriched uranium (HEU). The ability to continuously and independently (i.e. with a minimum of information from the facility operator) monitor not only the uranium mass balance but also the 235U mass balance in the facility could help support all three verification objectives described above. Two key capabilities required to achieve an independent and accurate material balance are 1) continuous, unattended monitoring of in-process UF6 and 2) monitoring of cylinders entering and leaving the facility. The continuous monitoring of in-process UF6 would rely on a combination of load-cell monitoring of the cylinders at the feed and withdrawal stations, online monitoring of gas enrichment, and a high-accuracy net weight measurement of the cylinder contents. The Online Enrichment Monitor (OLEM) is the instrument that would continuously measure the time-dependent relative uranium enrichment, E(t), in weight percent 235U, of the gas filling or being withdrawn from the cylinders. The OLEM design concept combines gamma-ray spectrometry using a collimated NaI(Tl) detector with gas pressure and temperature data to calculate the enrichment of the UF6

  15. Analysis of an indirect neutron signature for enhanced UF_6 cylinder verification

    International Nuclear Information System (INIS)

    Kulisek, J.A.; McDonald, B.S.; Smith, L.E.; Zalavadia, M.A.; Webster, J.B.

    2017-01-01

    The International Atomic Energy Agency (IAEA) currently uses handheld gamma-ray spectrometers combined with ultrasonic wall-thickness gauges to verify the declared enrichment of uranium hexafluoride (UF_6) cylinders. The current method provides relatively low accuracy for the assay of "2"3"5U enrichment, especially for natural and depleted UF_6. Furthermore, the current method provides no capability to assay the absolute mass of "2"3"5U in the cylinder due to the localized instrument geometry and limited penetration of the 186-keV gamma-ray signature from "2"3"5U. Also, the current verification process is a time-consuming component of on-site inspections at uranium enrichment plants. Toward the goal of a more-capable cylinder assay method, the Pacific Northwest National Laboratory has developed the hybrid enrichment verification array (HEVA). HEVA measures both the traditional 186-keV direct signature and a non-traditional, high-energy neutron-induced signature (HEVA_N_T). HEVA_N_T enables full-volume assay of UF_6 cylinders by exploiting the relatively larger mean free paths of the neutrons emitted from the UF_6. In this work, Monte Carlo modeling is used as the basis for characterizing HEVA_N_T in terms of the individual contributions to HEVA_N_T from nuclides and hardware components. Monte Carlo modeling is also used to quantify the intrinsic efficiency of HEVA for neutron detection in a cylinder-assay geometry. Modeling predictions are validated against neutron-induced gamma-ray spectra from laboratory measurements and a relatively large population of Type 30B cylinders spanning a range of enrichments. Implications of the analysis and findings on the viability of HEVA for cylinder verification are discussed, such as the resistance of the HEVA_N_T signature to manipulation by the nearby placement of neutron-conversion materials.

  16. Review of models used for determining consequences of UF6 release: Development of model evaluation criteria. Volume 1

    International Nuclear Information System (INIS)

    Nair, S.K.; Chambers, D.B.; Park, S.H.; Hoffman, F.O.

    1997-11-01

    The objective of this study is to examine the usefulness and effectiveness of currently existing models that simulate the release of uranium hexafluoride from UF 6 -handling facilities, subsequent reactions of UF 6 with atmospheric moisture, and the dispersion of UF 6 and reaction products in the atmosphere. The study evaluates screening-level and detailed public-domain models that were specifically developed for UF 6 and models that were originally developed for the treatment of dense gases but are applicable to UF 6 release, reaction, and dispersion. The model evaluation process is divided into three specific tasks: model-component evaluation; applicability evaluation; and user interface and quality assurance and quality control (QA/QC) evaluation. Within the model-component evaluation process, a model's treatment of source term, thermodynamics, and atmospheric dispersion are considered and model predictions are compared with actual observations. Within the applicability evaluation process, a model's applicability to Integrated Safety Analysis, Emergency Response Planning, and Post-Accident Analysis, and to site-specific considerations are assessed. Finally, within the user interface and QA/QC evaluation process, a model's user-friendliness, presence and clarity of documentation, ease of use, etc. are assessed, along with its handling of QA/QC. This document presents the complete methodology used in the evaluation process

  17. Nuclear criticality safety aspects of gaseous uranium hexafluoride (UF6) in the diffusion cascade

    International Nuclear Information System (INIS)

    Huffer, J.E.

    1997-04-01

    This paper determines the nuclear safety of gaseous UF 6 in the current Gaseous Diffusion Cascade and auxiliary systems. The actual plant safety system settings for pressure trip points are used to determine the maximum amount of HF moderation in the process gas, as well as the corresponding atomic number densities. These inputs are used in KENO V.a criticality safety models which are sized to the actual plant equipment. The ENO V.a calculation results confirm nuclear safety of gaseous UF 6 in plant operations

  18. Measurement of 235U content and flow of UF6 using delayed neutrons or gamma rays following induced fission

    International Nuclear Information System (INIS)

    Stromswold, D.C.; Peurrung, A.J.; Reeder, P.L.; Perkins, R.W.

    1996-06-01

    Feasibility experiments conducted at Pacific Northwest National Laboratory demonstrate that either delayed neutrons or energetic gamma rays from short-lived fission products can be used to monitor the blending of UF 6 gas streams. A 252 Cf neutron source was used to induce 235 U fission in a sample, and delayed neutrons and gamma rays were measured after the sample moved open-quotes down-stream.close quotes The experiments used a UO 2 powder that was transported down the pipe to simulate the flowing UF 6 gas. Computer modeling and analytic calculation extended the test results to a flowing UF 6 gas system. Neutron or gamma-ray measurements made at two downstream positions can be used to indicate both the 235 U content and UF 6 flow rate. Both the neutron and gamma-ray techniques have the benefits of simplicity and long-term reliability, combined with adequate sensitivity for low-intrusion monitoring of the blending process. Alternatively, measuring the neutron emission rate from (a, n) reactions in the UF 6 provides an approximate measure of the 235 U content without using a neutron source to induce fission

  19. Estimating Sampling Biases and Measurement Uncertainties of AIRS-AMSU-A Temperature and Water Vapor Observations Using MERRA Reanalysis

    Science.gov (United States)

    Hearty, Thomas J.; Savtchenko, Andrey K.; Tian, Baijun; Fetzer, Eric; Yung, Yuk L.; Theobald, Michael; Vollmer, Bruce; Fishbein, Evan; Won, Young-In

    2014-01-01

    We use MERRA (Modern Era Retrospective-Analysis for Research Applications) temperature and water vapor data to estimate the sampling biases of climatologies derived from the AIRS/AMSU-A (Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A) suite of instruments. We separate the total sampling bias into temporal and instrumental components. The temporal component is caused by the AIRS/AMSU-A orbit and swath that are not able to sample all of time and space. The instrumental component is caused by scenes that prevent successful retrievals. The temporal sampling biases are generally smaller than the instrumental sampling biases except in regions with large diurnal variations, such as the boundary layer, where the temporal sampling biases of temperature can be +/- 2 K and water vapor can be 10% wet. The instrumental sampling biases are the main contributor to the total sampling biases and are mainly caused by clouds. They are up to 2 K cold and greater than 30% dry over mid-latitude storm tracks and tropical deep convective cloudy regions and up to 20% wet over stratus regions. However, other factors such as surface emissivity and temperature can also influence the instrumental sampling bias over deserts where the biases can be up to 1 K cold and 10% wet. Some instrumental sampling biases can vary seasonally and/or diurnally. We also estimate the combined measurement uncertainties of temperature and water vapor from AIRS/AMSU-A and MERRA by comparing similarly sampled climatologies from both data sets. The measurement differences are often larger than the sampling biases and have longitudinal variations.

  20. Laboratory and pilot-plant studies on the conversion of uranyl nitrate hexahydrate to UF6 by fluidized-bed processes

    International Nuclear Information System (INIS)

    Youngblood, E.L.; Urza, I.J.; Cathers, G.I.

    1977-06-01

    This report describes laboratory and pilot-plant studies on the conversion of uranyl nitrate hexahydrate (UNH) to UF 6 and on purification of the UF 6 . Experimental laboratory studies on the removal of residual nitrate from uranium trioxide (UO 3 ) calcine and the fluorination of technetium and subsequent sorption on MgF 2 were conducted to support the pilot-plant work. Two engineering-scale pilot plants utilizing fluidized-bed processes were constructed for equipment and process testing of the calcination of UNH to UO 3 and the direct fluorination of UO 3 to UF 6

  1. Room temperature synthesis of porous SiO2 thin films by plasma enhanced chemical vapor deposition

    OpenAIRE

    Barranco Quero, Ángel; Cotrino Bautista, José; Yubero Valencia, Francisco; Espinós, J. P.; Rodríguez González-Elipe, Agustín

    2004-01-01

    Synthesis of porous SiO2 thin films in room temperature was carried out using plasma enhanced chemical vapor deposition (CVD) in an electron cyclotron resonance microwave reactor with a downstream configuration.The gas adsorption properties and the type of porosity of the SiO2 thin films were assessed by adsorption isotherms of toluene at room temperature.The method could also permit the tailoring synthesis of thin films when both composition and porosity can be simultaneously and independent...

  2. Transport of natural UF6 in a challenging environment

    International Nuclear Information System (INIS)

    Chollet, P.; Presta, A.

    2004-01-01

    At the entrance of the nuclear fuel cycle, the front-end material transportation takes a major and specific place. After years of stability the landscape of front-end industry is going toward significant changes regarding capacity, implementation of new technologies, imbalance of conversion capacity between geographical areas with increasing volumes of natural UF6 to transport and transport issues such as new regulations and denial of shipments by liners and ports. Facing this evolution the front end-industry is re-organizing its environment to increase robustness of the logistical chain: by being active in industrial organizations such as WNTI and WNA to share technical views and develop licensed standard transport equipment usable worldwide by developing other safe and reliable comprehensive logistics solutions as an alternative to conventional transport means. Our paper will describe the solutions under review to meet nuclear fuel cycle companies expectations: qualification of several robust logistics systems chartered vessels for maritime transport of UF6 specific 20' flat racks for safer handling of 48Y cylinders with future thermal protections

  3. Transport of natural UF6 in a challenging environment

    Energy Technology Data Exchange (ETDEWEB)

    Chollet, P.; Presta, A. [COGEMA Logistics (AREVA Group) (France)

    2004-07-01

    At the entrance of the nuclear fuel cycle, the front-end material transportation takes a major and specific place. After years of stability the landscape of front-end industry is going toward significant changes regarding capacity, implementation of new technologies, imbalance of conversion capacity between geographical areas with increasing volumes of natural UF6 to transport and transport issues such as new regulations and denial of shipments by liners and ports. Facing this evolution the front end-industry is re-organizing its environment to increase robustness of the logistical chain: by being active in industrial organizations such as WNTI and WNA to share technical views and develop licensed standard transport equipment usable worldwide by developing other safe and reliable comprehensive logistics solutions as an alternative to conventional transport means. Our paper will describe the solutions under review to meet nuclear fuel cycle companies expectations: qualification of several robust logistics systems chartered vessels for maritime transport of UF6 specific 20' flat racks for safer handling of 48Y cylinders with future thermal protections.

  4. Validation of the Cristallini Sampling Method for UF6 by High Precision Double-Spike Measurements

    OpenAIRE

    RICHTER STEPHAN; JAKOBSSON ULF; HIESS JOE; AMARAGGI D.

    2017-01-01

    The so-called "Cristallini Method" for sampling of UF6 by adsorption and hydrolysis in alumina pellets inside a fluorothene P-10 tube was developed by the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC) several years ago. This method has several advantages compared to the currently used sampling method, for which UF6 is distilled into a stainless steel tube for transportation, with hydrolysis and isotopic analysis being performed after shipping to the analyt...

  5. A structure for models of hazardous materials with complex behavior

    International Nuclear Information System (INIS)

    Rodean, H.C.

    1991-01-01

    Most atmospheric dispersion models used to assess the environmental consequences of accidental releases of hazardous chemicals do not have the capability to simulate the pertinent chemical and physical processes associated with the release of the material and its mixing with the atmosphere. The purpose of this paper is to present a materials sub-model with the flexibility to simulate the chemical and physical behaviour of a variety of materials released into the atmosphere. The model, which is based on thermodynamic equilibrium, incorporates the ideal gas law, temperature-dependent vapor pressure equations, temperature-dependent dissociation reactions, and reactions with atmospheric water vapor. The model equations, written in terms of pressure ratios and dimensionless parameters, are used to construct equilibrium diagrams with temperature and the mass fraction of the material in the mixture as coordinates. The model's versatility is demonstrated by its application to the release of UF 6 and N 2 O 4 , two materials with very different physical and chemical properties. (author)

  6. Crystal field effect in the uranium compounds - model calculations for CsUF/sub 6/, Cs/sub 2/UCl/sub 6/ and UCl/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Gajek, Z.; Mulak, J.; Faucher, M.

    1987-01-01

    A practical crystal field model allowing one to estimate the crystal field parameters from first principles is presented and applied to the actinide compounds. The model results directly from the renormalization (and reduction) procedure of the true Schroedinger equation for an effective Hamiltonian acting on the 5f spin-orbitals only. In practice this approach becomes convergent with the ab initio model of Newman. Three ionic uranium compounds: CsUF/sub 6/, Cs/sub 2/UCl/sub 6/ and UCl/sub 4/ have served as examples of the application. The results obtained, particularly for the first two compounds, are in good agreement with the experimental data. The contributions of different mechanisms responsible for the crystal field effect are discussed.

  7. Effect of impact angle on vaporization

    Science.gov (United States)

    Schultz, Peter H.

    1996-09-01

    Impacts into easily vaporized targets such as dry ice and carbonates generate a rapidly expanding vapor cloud. Laboratory experiments performed in a tenuous atmosphere allow deriving the internal energy of this cloud through well-established and tested theoretical descriptions. A second set of experiments under near-vacuum conditions provides a second measure of energy as the internal energy converts to kinetic energy of expansion. The resulting data allow deriving the vaporized mass as a function of impact angle and velocity. Although peak shock pressures decrease with decreasing impact angle (referenced to horizontal), the amount of impact-generated vapor is found to increase and is derived from the upper surface. Moreover, the temperature of the vapor cloud appears to decrease with decreasing angle. These unexpected results are proposed to reflect the increasing roles of shear heating and downrange hypervelocity ricochet impacts created during oblique impacts. The shallow provenance, low temperature, and trajectory of such vapor have implications for larger-scale events, including enhancement of atmospheric and biospheric stress by oblique terrestrial impacts and impact recycling of the early atmosphere of Mars.

  8. The Accuracy of the Sysmex UF-1000i in Urine Bacterial Detection Compared With the Standard Urine Analysis and Culture.

    Science.gov (United States)

    Erdman, Patrick; Anderson, Brian; Zacko, J Christopher; Taylor, Kirk; Donaldson, Keri

    2017-11-01

    - Urinary tract infections are characterized by the presence of microbial pathogens within the urinary tract. They represent one of the most common infections in hospitalized and clinic patients. - To model the parameters of the Sysmex UF-1000i to the gold standard, urine culture, and to compare the detection of dipstick leukocyte esterase and nitrates to urine cultures and UF-1000i results. - Data were compared from urine samples collected in sterile containers for bacterial culture and microscopic analysis. One sample was used to inoculate a 5% sheep blood agar and MacConkey agar plate using a 0.001-mL calibrated loop. The second sample was analyzed by urinalysis-associated microscopy. The media plates were investigated for growth after 18 to 24 hours of aerobic incubation at 37°C. The second sample was analyzed for bacteria and leukocytes with the Sysmex UF-1000i according to the manufacturer's guidelines. Three definitions for culture results, sensitivity, and specificity at different cutoff values were calculated for the UF-1000i. - The negative predictive value for any positive culture in the adult population included in the study was 95.5%, and the negative predictive value for positive cultures containing growth of 100 000 or more colony-forming units was 99.3% using the Sysmex UF-1000i. - Sysmex UF-1000i showed 98% sensitivity and 93.7% specificity with a 95.5% negative predictive value. Thus, a negative screen with the UF-1000i using defined thresholds for white blood cell counts and bacteria was likely to be a true negative, decreasing the need for presumptive antibiotics.

  9. Flashed-feed VMD configuration as a novel method for eliminating temperature polarization effect and enhancing water vapor flux

    KAUST Repository

    Alsaadi, Ahmad Salem; Alpatova, Alla; Lee, Jung Gil; Francis, Lijo; Ghaffour, NorEddine

    2018-01-01

    The coupling of heat and mass transfer in membrane distillation (MD) process makes enhancing water vapor flux and determining MD membrane mass transfer coefficient (MTC) fairly challenging due to the development of temperature gradient near

  10. Benchmark calculation of APOLLO-2 and SLAROM-UF in a fast reactor lattice

    International Nuclear Information System (INIS)

    Hazama, T.

    2009-07-01

    A lattice cell benchmark calculation is carried out for APOLLO2 and SLAROM-UF on the infinite lattice of a simple pin cell featuring a fast reactor. The accuracy in k-infinity and reaction rates is investigated in their reference and standard level calculations. In the 1. reference level calculation, APOLLO2 and SLAROM-UF agree with the reference value of k-infinity obtained by a continuous energy Monte Carlo calculation within 50 pcm. However, larger errors are observed in a particular reaction rate and energy range. The major problem common to both codes is in the cross section library of 239 Pu in the unresolved energy range. In the 2. reference level calculation, which is based on the ECCO 1968 group structure, both results of k-infinity agree with the reference value within 100 pcm. The resonance overlap effect is observed by several percents in cross sections of heavy nuclides. In the standard level calculation based on the APOLLO2 library creation methodology, a discrepancy appears by more than 300 pcm. A restriction is revealed in APOLLO2. Its standard cross section library does not have a sufficiently small background cross section to evaluate the self shielding effect on 56 Fe cross sections. The restriction can be removed by introducing the mixture self-shielding treatment recently introduced to APOLLO2. SLAROM-UF original standard level calculation based on the JFS-3 library creation methodology is the best among the standard level calculations. Improvement from the SLAROM-UF standard level calculation is achieved mainly by use of a proper weight function for light or intermediate nuclides. (author)

  11. Technology Assessment for Proof-of-Concept UF6 Cylinder Unique Identification Task 3.1.2 Report – Survey and Assessment of Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wylie, Joann; Hockert, John

    2014-04-24

    The National Nuclear Security Administration (NNSA) Office of Nonproliferation and International Security’s (NA-24) Next Generation Safeguards Initiative (NGSI) and the nuclear industry have begun to develop approaches to identify and monitor uranium hexafluoride (UF6) cylinders. The NA-24 interest in a global monitoring system for UF6 cylinders relates to its interest in supporting the International Atomic Energy Agency (IAEA) in deterring and detecting diversion of UF6 (e.g., loss of cylinder in transit) and undeclared excess production at conversion and enrichment facilities. The industry interest in a global monitoring system for UF6 cylinders relates to the improvements in operational efficiencies that such a system would provide. This task is part of an effort to survey and assess technologies for a UF6 cylinder to identify candidate technologies for a proof-of-concept demonstration and evaluation for the Cylinder Identification System (CIS).

  12. Presentation and interpretation of field experiments of gaseous UF{sub 6} releases in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Crabol, B.; Boulaud, D.; Deville-Cavelin, G. [CEA/Inst. de Protection et de Surete Nucleaire, Dept. de Protection de l' Environnement et des Installations, Fontenay-aux-Roses (France); Geisse, C.; Iacona, L. [EURODIF/Production, Site de Tricastin, Pierrelatte Cedex (France)

    1992-07-01

    An experimental programme concerning the behaviour of UF{sub 6} released in gaseous phase in the atmosphere has been conducted in the years 1986-1989 by the French Atomic Energy Commission and EURODIF. Three field tests have been performed on the CEA/CESTA experimental site. These experiments permitted to get information about the kinetics of the hydrolysis reaction of the UF{sub 6}, the behaviour of the hydrolysis products in the atmosphere and the granulometry of the solid particles. (author)

  13. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

    Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

  14. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    International Nuclear Information System (INIS)

    Deb, K.; Bera, A.; Saha, B.; Bhowmik, K. L.; Chattopadhyay, K. K.

    2016-01-01

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  15. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Deb, K.; Bera, A.; Saha, B., E-mail: biswajit.physics@gmail.com [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Bhowmik, K. L. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Department of Chemistry, Bir Bikram Memorial College, Agartala, West Tripura 799004 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

    2016-05-23

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  16. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    Science.gov (United States)

    Deb, K.; Bhowmik, K. L.; Bera, A.; Chattopadhyay, K. K.; Saha, B.

    2016-05-01

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  17. Thermochemical study of 2,4-, 2,6- and 3,4-dihydroxybenzoic acids in the liquid phase using a TG apparatus

    International Nuclear Information System (INIS)

    Vecchio, Stefano; Brunetti, Bruno

    2011-01-01

    Research highlights: → Vapor pressures of solid and liquid 2,4- 2,6- and 3,4-dihydroxybenzoic acids, that don't decompose appreciably in the temperature range considered, were determined by torsion-effusion technique and thermogravimetry, respectively. → Agreement between the experimental sublimation vapor pressures and literature data recently published is good for all the three isomers. → From the temperature dependence of vapor pressure the molar enthalpies of sublimation and vaporization were determined at the middle of the respective experimental temperature intervals. → For validation of TG pressure data, the TG vapor pressures of solid ferrocene and 1,2-dihydroxybenzoic acid were successfully compared with the corresponding literature values. → The following increasing-order of volatility can be established: 2,6-dihydroxybenzoic acid l g H m o ( ) were determined, respectively, at the middle of the respective temperature intervals. The melting temperatures and the molar enthalpies of fusion of these compounds were measured by d.s.c. The vapor pressures of these compounds in the solid state, measured by torsion-effusion technique, were compared with recently published data, while the corresponding molar sublimation enthalpies were determined. In order to validate the vapor pressure results determined by TG, the experimental vapor pressure data regarding solid ferrocene and 1,2-dihydroxybenzoic acid were successfully compared with literature values in the range 20-200 Pa. In addition, the experimental molar enthalpies of fusion were compared with those calculated by subtracting the molar vaporization enthalpies to the sublimation ones, both adjusted to their respective melting temperatures. Finally, the standard (p o = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation, corrected at the reference temperature of 298.15 K, have been calculated using the estimated heat capacity differences between gas and liquid for vaporization

  18. Tight ceramic UF membrane as RO pre-treatment: the role of electrostatic interactions on phosphate rejection.

    Science.gov (United States)

    Shang, Ran; Verliefde, Arne R D; Hu, Jingyi; Zeng, Zheyi; Lu, Jie; Kemperman, Antoine J B; Deng, Huiping; Nijmeijer, Kitty; Heijman, Sebastiaan G J; Rietveld, Luuk C

    2014-01-01

    Phosphate limitation has been reported as an effective approach to inhibit biofouling in reverse osmosis (RO) systems for water purification. The rejection of dissolved phosphate by negatively charged TiO2 tight ultrafiltration (UF) membranes (1 kDa and 3 kDa) was observed. These membranes can potentially be adopted as an effective process for RO pre-treatment in order to constrain biofouling by phosphate limitation. This paper focuses on electrostatic interactions during tight UF filtration. Despite the larger pore size, the 3 kDa ceramic membrane exhibited greater phosphate rejection than the 1 kDa membrane, because the 3 kDa membrane has a greater negative surface charge and thus greater electrostatic repulsion against phosphate. The increase of pH from 6 to 8.5 led to a substantial increase in phosphate rejection by both membranes due to increased electrostatic repulsion. At pH 8.5, the maximum phosphate rejections achieved by the 1 kDa and 3 kDa membrane were 75% and 86%, respectively. A Debye ratio (ratio of the Debye length to the pore radius) is introduced in order to evaluate double layer overlapping in tight UF membranes. Threshold Debye ratios were determined as 2 and 1 for the 1 kDa and 3 kDa membranes, respectively. A Debye ratio below the threshold Debye ratio leads to dramatically decreased phosphate rejection by tight UF membranes. The phosphate rejection by the tight UF, in combination with chemical phosphate removal by coagulation, might accomplish phosphate-limited conditions for biological growth and thus prevent biofouling in the RO systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Modelling of the behaviour of a UF_6 container in a fire

    International Nuclear Information System (INIS)

    Pinton, Eric

    1996-01-01

    This thesis is justified by the safety needs about storage and transport of UF_6 containers. To define their behaviour under fire conditions, a modelling was developed. Before tackling the numerical modelling, a phenomenological interpretation with experimental results of containers inside a furnace (800 C) during a fixed period was carried out. The internal heat transfers were considerably improved with these results. The 2D elaborated model takes into account most of the physical phenomena encountered in this type of situation (boiling, evaporation, condensation, radiant heat transfers through an absorbing gas, convection, pressurisation, thermal contact resistance, UF_6 expansion, solid core sinking in the liquid, elastic and plastic deformations of the steel container). This model was successfully confronted with experiments. (author) [fr

  20. Radiation-Triggered Surveillance for UF6 Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Michael M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-12-01

    This paper recommends the use of radiation detectors, singly or in sets, to trigger surveillance cameras. Ideally, the cameras will monitor cylinders transiting the process area as well as the process area itself. The general process area will be surveyed to record how many cylinders have been attached and detached to the process between inspections. Rad-triggered cameras can dramatically reduce the quantity of recorded images, because the movement of personnel and equipment not involving UF6 cylinders will not generate a surveillance review file.

  1. Building blocks for ionic liquids: Vapor pressures and vaporization enthalpies of 1-(n-alkyl)-imidazoles

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Portnova, Svetlana V.; Verevkin, Sergey P.; Skrzypczak, Andrzej; Schubert, Thomas

    2011-01-01

    Highlights: → We measured vapor pressures of the 1-(n-alkyl)-imidazoles by transpiration method. → Variations on the alkyl chain length n were C 3 , C 5 -C 7 , and C 9 -C 10 . → Enthalpies of vaporization were derived from (p, T) dependencies. → Enthalpies of vaporization at 298.15 K were linear dependent on the chain length. - Abstract: Vapor pressures of the linear 1-(n-alkyl)-imidazoles with the alkyl chain C 3 , C 5 -C 7 , and C 9 -C 10 have been measured by the transpiration method. The molar enthalpies of vaporization Δ l g H m of these compounds were derived from the temperature dependencies of vapor pressures. A linear correlation of enthalpies of vaporization Δ l g H m (298.15 K) of the 1-(n-alkyl)-imidazoles with the chain length has been found.

  2. Medicinal Cannabis: In Vitro Validation of Vaporizers for the Smoke-Free Inhalation of Cannabis.

    Science.gov (United States)

    Lanz, Christian; Mattsson, Johan; Soydaner, Umut; Brenneisen, Rudolf

    2016-01-01

    Inhalation by vaporization is a promising application mode for cannabis in medicine. An in vitro validation of 5 commercial vaporizers was performed with THC-type and CBD-type cannabis. Gas chromatography/mass spectrometry was used to determine recoveries of total THC (THCtot) and total CBD (CBDtot) in the vapor. High-performance liquid chromatography with photodiode array detection was used for the quantitation of acidic cannabinoids in the residue and to calculate decarboxylation efficiencies. Recoveries of THCtot and CBDtot in the vapor of 4 electrically-driven vaporizers were 58.4 and 51.4%, 66.8 and 56.1%, 82.7 and 70.0% and 54.6 and 56.7% for Volcano Medic®, Plenty Vaporizer®, Arizer Solo® and DaVinci Vaporizer®, respectively. Decarboxylation efficiency was excellent for THC (≥ 97.3%) and CBD (≥ 94.6%). The gas-powered Vape-or-Smoke™ showed recoveries of THCtot and CBDtot in the vapor of 55.9 and 45.9%, respectively, and a decarboxylation efficiency of ≥ 87.7 for both cannabinoids. However, combustion of cannabis was observed with this device. Temperature-controlled, electrically-driven vaporizers efficiently decarboxylate inactive acidic cannabinoids and reliably release their corresponding neutral, active cannabinoids. Thus, they offer a promising application mode for the safe and efficient administration of medicinal cannabis.

  3. Vapor Pressure of Antimony Triiodide

    Science.gov (United States)

    2017-12-07

    unlimited. iii Contents List of Figures iv 1. Introduction 1 2. Vapor Pressure 1 3. Experiment 3 4. Discussion and Measurements 5 5...SbI3 as a function of temperature ......................... 6 Approved for public release; distribution is unlimited. 1 1. Introduction ...single-crystal thin films of n-type (Bi,Sb)2(Te,Se)3 materials presents new doping challenges because it is a nonequilibrium process. (Bi,Sb)2(Te,Se)3

  4. Circulation system for flowing uranium hexafluoride cavity reactor experiments

    International Nuclear Information System (INIS)

    Jaminet, J.F.; Kendall, J.S.

    1976-01-01

    Accomplishment of the UF 6 critical cavity experiments, currently in progress, and planned confined flowing UF 6 initial experiments requires development of reliable techniques for handling heated UF 6 throughout extended ranges of temperature, pressure, and flow rate. The development of three laboratory-scale flow systems for handling gaseous UF 6 at temperatures up to 500 K, pressures up to approximately 40 atm, and continuous flow rates up to approximately 50 g/s is presented. A UF 6 handling system fabricated for static critical tests currently being conducted at Los Alamos Scientific Laboratory (LASL) is described. The system was designed to supply UF 6 to a double-walled aluminum core canister assembly at temperatures between 300 K and 400 K and pressures up to 4 atm. A second UF 6 handling system designed to provide a circulating flow of up to 50 g/s of gaseous UF 6 in a closed-loop through a double-walled aluminum core canister with controlled temperature and pressure is described

  5. New approaches to the study of lanthanide/actinide chloride: aluminum chloride vapor phase complexes

    International Nuclear Information System (INIS)

    Peterson, E.J.; Caird, J.A.; Carnall, W.T.; Hessler, J.P.; Hoekstra, H.R.; Williams, C.W.

    1979-01-01

    The spectrophotometric technique for vapor density measurements of complexed metal ions has been reformulated to account for temperature dependent effects and multi-species systems. Analysis of vapor pressure information indicates that the NdCl 3 --AlCl 3 and HoCl 3 --AlCl 3 systems are adequately explained by the existence of three vapor species. The two higher molecular weight complexes LnAl 4 Cl 15 and LnAl 3 Cl 12 were first proposed by Oeye and Gruen. The newly identified higher temperature species, HoAl 2 Cl 9 , contributes significantly to the vapor density above 750 0 K and below 3 atm of dimer pressure. In view of the consistency of the Nd +3 and Ho +3 chemistry the data for the Sm +3 system should be viewed with reservation. A new method for vapor density measurements involving use of radioactive tracers has been discussed in terms of its applicability to the study of (Ln,An)Cl 3 (AlCl 3 )/sub x/ systems

  6. Estimating evaporative vapor generation from automobiles based on parking activities

    International Nuclear Information System (INIS)

    Dong, Xinyi; Tschantz, Michael; Fu, Joshua S.

    2015-01-01

    A new approach is proposed to quantify the evaporative vapor generation based on real parking activity data. As compared to the existing methods, two improvements are applied in this new approach to reduce the uncertainties: First, evaporative vapor generation from diurnal parking events is usually calculated based on estimated average parking duration for the whole fleet, while in this study, vapor generation rate is calculated based on parking activities distribution. Second, rather than using the daily temperature gradient, this study uses hourly temperature observations to derive the hourly incremental vapor generation rates. The parking distribution and hourly incremental vapor generation rates are then adopted with Wade–Reddy's equation to estimate the weighted average evaporative generation. We find that hourly incremental rates can better describe the temporal variations of vapor generation, and the weighted vapor generation rate is 5–8% less than calculation without considering parking activity. - Highlights: • We applied real parking distribution data to estimate evaporative vapor generation. • We applied real hourly temperature data to estimate hourly incremental vapor generation rate. • Evaporative emission for Florence is estimated based on parking distribution and hourly rate. - A new approach is proposed to quantify the weighted evaporative vapor generation based on parking distribution with an hourly incremental vapor generation rate

  7. Radiation dose rates from UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Friend, P.J. [Urenco, Capenhurst (United Kingdom)

    1991-12-31

    This paper describes the results of many studies, both theoretical and experimental, which have been carried out by Urenco over the last 15 years into radiation dose rates from uranium hexafluoride (UF{sub 6}) cylinders. The contents of the cylinder, its history, and the geometry all affect the radiation dose rate. These factors are all examined in detail. Actual and predicted dose rates are compared with levels permitted by IAEA transport regulations.

  8. Phase relationship, vaporization, and thermodynamic properties of the lanthanum--boron system

    International Nuclear Information System (INIS)

    Storms, E.; Mueller, B.

    1978-01-01

    The La-B system was studied between LaB/sub 4.24/ and LaB/sub 29.2/, and between 1400 and 2100 K to determine the phase relationship, the chemical activity of the components, the vaporization rate, and the vapor composition. A blue colored phase near LaB 9 was found to exist between purple colored LaB 6 and elemental boron. Diffusion is so much slower than vaporization that large composition differences can exist between the surface and the interior which, nevertheless, produce a steady state loss rate from freely vaporizing material. The flux at 1700 K is 6 x 10 -10 g/cm 2 s for LaB 4 +LaB 6 and 7 x 10 -11 g/cm 2 s for LaB 6 + LaB 9 . There is an activation energy which lowers the vaporization rate of boron from LaB 6 . Freely vaporizing material will have a steady state surface composition between LaB/sub 6.04/ and LaB/sub 6.07/, depending on temperature, purity, and interior composition. The free energy of formation of LaB 6 is (0.07lT - 351)kJ/mol between 1700 and 2100 K

  9. Vaporization of the prototypical ionic liquid BMImNTf₂ under equilibrium conditions: a multitechnique study.

    Science.gov (United States)

    Brunetti, Bruno; Ciccioli, Andrea; Gigli, Guido; Lapi, Andrea; Misceo, Nicolaemanuele; Tanzi, Luana; Vecchio Ciprioti, Stefano

    2014-08-07

    The vaporization behaviour and thermodynamics of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonylimide (BMImNTf2) were studied by combining the Knudsen Effusion Mass Loss (KEML) and Knudsen Effusion Mass Spectrometry (KEMS) techniques. KEML studies were carried out in a large temperature range (398-567) K by using effusion orifices with 0.3, 1, and 3 mm diameters. The vapor pressures so measured revealed no kinetically hindered vaporization effects and provided second-law vaporization enthalpies at the mean experimental temperatures in close agreement with literature. By exploiting the large temperature range covered, the heat capacity change associated with vaporization was estimated, resulting in a value of -66.8 J K(-1) mol(-1), much lower than that predicted from calorimetric measurements on the liquid phase and theoretical calculations on the gas phase. The conversion of the high temperature vaporization enthalpy to 298 K was discussed and the value Δ(l)(g)H(m)(298 K) = (128.6 ± 1.3) kJ mol(-1) assessed on the basis of data from literature and present work. Vapor pressure data were also processed by the third-law procedure using different estimations for the auxiliary thermal functions, and a Δ(l)(g)H(m)(298 K) consistent with the assessed value was obtained, although the overall agreement is sensitive to the accuracy of heat capacity data. KEMS measurements were carried out in the lower temperature range (393-467) K and showed that the largely prevailing ion species is BMIm(+), supporting the common view of BMImNTf2 vaporizing as individual, neutral ion pairs also under equilibrium conditions. By monitoring the mass spectrometric signal of this ion as a function of temperature, a second-law Δ(l)(g)H(m)(298 K) of 129.4 ± 7.3 kJ mol(-1) was obtained, well consistent with KEML and literature results. Finally, by combining KEML and KEMS measurements, the electron impact ionization cross section of BMIm(+) was estimated.

  10. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

    Science.gov (United States)

    McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

    2007-09-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude.

  11. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium

    International Nuclear Information System (INIS)

    McCarron, Daniel J.; Hughes, Ifan G.; Tierney, Patrick; Cornish, Simon L.

    2007-01-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D 2 transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude

  12. Heat transfer measurements in a forced convection loop with two molten-fluoride salts: LiF--BeF2--ThF2--UF4 and eutectic NaBF4--NaF

    International Nuclear Information System (INIS)

    Silverman, M.D.; Huntley, W.R.; Robertson, H.E.

    1976-10-01

    Heat transfer coefficients were determined experimentally for two molten-fluoride salts [LiF-BeF 2 -ThF 2 -UF 4 (72-16-12-0.3 mole %) and NaBF 4 -NaF (92-8 mole %] proposed as the fuel salt and coolant salt, respectively, for molten-salt breeder reactors. Information was obtained over a wide range of variables, with salt flowing through 12.7-mm-OD (0.5-in.) Hastelloy N tubing in a forced convection loop (FCL-2b). Satisfactory agreement with the empirical Sieder-Tate correlation was obtained in the fully developed turbulent region at Reynolds moduli above 15,000 and with a modified Hausen equation in the extended transition region (Re approx.2100-15,000). Insufficient data were obtained in the laminar region to allow any conclusions to be drawn. These results indicate that the proposed salts behave as normal heat transfer fluids with an extended transition region

  13. Estimating enthalpy of vaporization from vapor pressure using Trouton's rule.

    Science.gov (United States)

    MacLeod, Matthew; Scheringer, Martin; Hungerbühler, Konrad

    2007-04-15

    The enthalpy of vaporization of liquids and subcooled liquids at 298 K (delta H(VAP)) is an important parameter in environmental fate assessments that consider spatial and temporal variability in environmental conditions. It has been shown that delta H(VAP)P for non-hydrogen-bonding substances can be estimated from vapor pressure at 298 K (P(L)) using an empirically derived linear relationship. Here, we demonstrate that the relationship between delta H(VAP)and PL is consistent with Trouton's rule and the ClausiusClapeyron equation under the assumption that delta H(VAP) is linearly dependent on temperature between 298 K and the boiling point temperature. Our interpretation based on Trouton's rule substantiates the empirical relationship between delta H(VAP) degree and P(L) degrees for non-hydrogen-bonding chemicals with subcooled liquid vapor pressures ranging over 15 orders of magnitude. We apply the relationship between delta H(VAP) degrees and P(L) degrees to evaluate data reported in literature reviews for several important classes of semivolatile environmental contaminants, including polycyclic aromatic hydrocarbons, chlorobenzenes, polychlorinated biphenyls and polychlorinated dibenzo-dioxins and -furans and illustrate the temperature dependence of results from a multimedia model presented as a partitioning map. The uncertainty associated with estimating delta H(VAP)degrees from P(L) degrees using this relationship is acceptable for most environmental fate modeling of non-hydrogen-bonding semivolatile organic chemicals.

  14. A study on vapor explosions

    International Nuclear Information System (INIS)

    Takagi, N.; Shoji, M.

    1979-01-01

    An experimental study was carried out for vapor explosions of molten tin falling in water. For various initial metal temperatures and subcooling of water, transient pressure of the explosions, relative frequency of the explosions and the position where the explosions occur were measured in detail. The influence of ambient pressure was also investigated. From the results, it was concluded that the vapor explosion is closely related to the collapse of a vapor film around the molten metal. (author)

  15. Analysis of an indirect neutron signature for enhanced UF{sub 6} cylinder verification

    Energy Technology Data Exchange (ETDEWEB)

    Kulisek, J.A., E-mail: Jonathan.Kulisek@pnnl.gov; McDonald, B.S.; Smith, L.E.; Zalavadia, M.A.; Webster, J.B.

    2017-02-21

    The International Atomic Energy Agency (IAEA) currently uses handheld gamma-ray spectrometers combined with ultrasonic wall-thickness gauges to verify the declared enrichment of uranium hexafluoride (UF{sub 6}) cylinders. The current method provides relatively low accuracy for the assay of {sup 235}U enrichment, especially for natural and depleted UF{sub 6}. Furthermore, the current method provides no capability to assay the absolute mass of {sup 235}U in the cylinder due to the localized instrument geometry and limited penetration of the 186-keV gamma-ray signature from {sup 235}U. Also, the current verification process is a time-consuming component of on-site inspections at uranium enrichment plants. Toward the goal of a more-capable cylinder assay method, the Pacific Northwest National Laboratory has developed the hybrid enrichment verification array (HEVA). HEVA measures both the traditional 186-keV direct signature and a non-traditional, high-energy neutron-induced signature (HEVA{sub NT}). HEVA{sub NT} enables full-volume assay of UF{sub 6} cylinders by exploiting the relatively larger mean free paths of the neutrons emitted from the UF{sub 6}. In this work, Monte Carlo modeling is used as the basis for characterizing HEVA{sub NT} in terms of the individual contributions to HEVA{sub NT} from nuclides and hardware components. Monte Carlo modeling is also used to quantify the intrinsic efficiency of HEVA for neutron detection in a cylinder-assay geometry. Modeling predictions are validated against neutron-induced gamma-ray spectra from laboratory measurements and a relatively large population of Type 30B cylinders spanning a range of enrichments. Implications of the analysis and findings on the viability of HEVA for cylinder verification are discussed, such as the resistance of the HEVA{sub NT} signature to manipulation by the nearby placement of neutron-conversion materials.

  16. Hybrid coagulation-UF processes for spent filter backwash water treatment: a comparison studies for PAFCl and FeCl3 as a pre-treatment.

    Science.gov (United States)

    Ebrahimi, Afshin; Amin, Mohammad Mehdi; Pourzamani, Hamidreza; Hajizadeh, Yaghoub; Mahvi, Amir Hossein; Mahdavi, Mokhtar; Rad, Mohammad Hassan Rabie

    2017-08-01

    In this study, the reclamation of clean water from spent filter backwash water (SFBW) was investigated through pilot-scale experiments. The pilot plant consisted of pre-sedimentation, coagulation, flocculation, clarification, and ultrafiltration (UF). Two coagulants of PAFCl and FeCl 3 were investigated with respect to their performance on treated SFBW quality and UF membrane fouling. At the optimum dose of PAFCl and FeCl 3 turbidity removal of 99.6 and 99.4% was attained, respectively. PAFCl resulted in an optimum UV 254 , TOC, and DOC removal of 80, 83.6, and 72.7%, respectively, and FeCl 3 caused the removal of those parameters by 76.7, 80.9, and 65.9%, respectively. PAFCl removed hydrophilic and transphilic constituent better than FeCl 3 , but FeCl 3 had, to some extent, higher affinities to a hydrophobic fraction. It was concluded that PAFCl showed a better coagulation performance in most cases and caused a lower membrane fouling rate compared to FeCl 3 . Finally, the treated SFBW with both coagulant-UF systems met the drinking water standards.

  17. Guggenheim's rule and the enthalpy of vaporization of simple and polar fluids, molten salts, and room temperature ionic liquids.

    Science.gov (United States)

    Weiss, Volker C

    2010-07-22

    One of Guggenheim's many corresponding-states rules for simple fluids implies that the molar enthalpy of vaporization (determined at the temperature at which the pressure reaches 1/50th of its critical value, which approximately coincides with the normal boiling point) divided by the critical temperature has a value of roughly 5.2R, where R is the universal gas constant. For more complex fluids, such as strongly polar and ionic fluids, one must expect deviations from Guggenheim's rule. Such a deviation has far-reaching consequences for other empirical rules related to the vaporization of fluids, namely Guldberg's rule and Trouton's rule. We evaluate these characteristic quantities for simple fluids, polar fluids, hydrogen-bonding fluids, simple inorganic molten salts, and room temperature ionic liquids (RTILs). For the ionic fluids, the critical parameters are not accessible to direct experimental observation; therefore, suitable extrapolation schemes have to be applied. For the RTILs [1-n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides, where the alkyl chain is ethyl, butyl, hexyl, or octyl], the critical temperature is estimated by extrapolating the surface tension to zero using Guggenheim's and Eotvos' rules; the critical density is obtained using the linear-diameter rule. It is shown that the RTILs adhere to Guggenheim's master curve for the reduced surface tension of simple and moderately polar fluids, but that they deviate significantly from his rule for the reduced enthalpy of vaporization of simple fluids. Consequences for evaluating the Trouton constant of RTILs, the value of which has been discussed controversially in the literature, are indicated.

  18. Study of vaporization of sodium metaborate by transpiration thermogravimetry and Knudsen effusion mass spectrometry.

    Science.gov (United States)

    Narasimhan, T S Lakshmi; Viswanathan, R; Nalini, S

    2011-11-17

    The vaporization of solid sodium metaborate NaBO(2)(s) was studied by transpiration thermogravimetry (TTG) and Knudsen effusion mass spectrometry (KEMS). The transpiration measurements, performed for the first time on NaBO(2)(s), involved use of argon as the carrier gas for vapor transport and derivation of vapor pressure of NaBO(2)(g) (by assuming it as the sole vapor species) through many flow-dependence runs and temperature-dependence runs in the temperature range 1075-1218 K. The KEMS measurements performed in the temperature range 1060-1185 K confirmed NaBO(2)(g) as the principal vapor species over NaBO(2)(s), in accord with the previously reported KEMS studies. The values of p(NaBO(2)) obtained by both TTG and KEMS are consistent within the uncertainties associated with each method and so are the second- and third-law values of enthalpy of sublimation, the latter aspect consistently missing in all previous vaporization studies. The results of both TTG and KEMS were combined to recommend the following thermodynamic parameters pertinent to the sublimation reaction, NaBO(2)(s) = NaBO(2)(g): Log{p(NaBO(2))/Pa} = -(17056 ± 441)/(T/K) + (14.73 ± 0.35) for the temperature range 1060-1218 K; Δ(r)H°(m)(298.15 K) = (346.3 ± 9.4) kJ·mol(-1); and Δ(r)S°(m)(298.15 K) = (210.2 ± 6.8) J·mol(-1)·K(-1).

  19. Mass spectrometric study of Nd2S3 vaporization

    International Nuclear Information System (INIS)

    Fenochka, B.V.

    1987-01-01

    The authors conduct a mass-spectrometric study of neodymium(III) sulfide vaporization. The chemical composition of the samples was stoichiometric and the samples were vaporized from tantalum effusion cells. When the vapor over Nd 2 S 3 is ionized by electrons the mass spectra shows monovalent cations of Nd, S, NdS, and NdO. The enthalpy of vaporization if Nd atoms from Nd 2 S 3 at average experimental temperatures and the standard enthalpy of reaction is shown. Also presented is the enthalpy of vaporization of NdS molecules from Nd 2 S 3 at average experimental temperatures and the standard enthalpy of reaction

  20. Transparent conductive zinc-oxide-based films grown at low temperature by mist chemical vapor deposition

    International Nuclear Information System (INIS)

    Shirahata, Takahiro; Kawaharamura, Toshiyuki; Fujita, Shizuo; Orita, Hiroyuki

    2015-01-01

    Atmospheric pressure mist chemical vapor deposition (Mist–CVD) systems have been developed to grow zinc-oxide-based (ZnO-based) transparent conductive oxide (TCO) films. Low-resistive aluminum-doped ZnO (AZO) TCOs, showing resistivity of the order on 10"−"4 Ωcm, previously were grown using a safe source material zinc acetate [Zn(ac)_2], at a growth temperature as high as 500 °C. To grow superior TCOs at lower temperatures, we proposed the addition of NH_3 to accelerate the reaction of acetylacetonate compounds. As the result, we could grow gallium-doped ZnO (GZO) TCOs with a resistivity of 2.7 × 10"−"3 Ω cm and transmittance higher than 90% at 300 °C by using zinc acetylacetonate [Zn(acac)_2] as the Zn source. To grow boron-doped ZnO (BZO) TCOs at a lower growth temperature of 200 °C, we used boron doping along with a toluene solution of diethylzinc (DEZ), that maintained high reactivity without being flammable. These BZO TCOs showed a resistivity of 1.5 × 10"−"3 Ω cm and transmittance higher than 90%, despite the use of a non-vacuum-based open-air technology. - Highlights: • Introduction of Mist–CVD as a non-vacuum-based, safe, and cost-effective growth technology • Process evolution of the growth technology to lower the growth temperature. • Achievement of low resistive ZnO films at 200oC.

  1. Transparent conductive zinc-oxide-based films grown at low temperature by mist chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shirahata, Takahiro [New Energy and Environmental Business Division, Toshiba Mitsubishi-Electric Industrial Systems Corporation, Kobe International Business Center (KIBC) 509, 5-5-2 Minatojima-Minami, Chuo-Ku, Kobe 650-0047 (Japan); Kawaharamura, Toshiyuki [Research Institute, Kochi University of Technology, Kami, Kochi 780-8502 (Japan); School of Systems Engineering, Kochi University of Technology, Kami, Kochi 780-8502 (Japan); Fujita, Shizuo, E-mail: fujitasz@kuee.kyoto-u.ac.jp [Photonics and Electronics Science and Engineering Center, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8520 (Japan); Orita, Hiroyuki [New Energy and Environmental Business Division, Toshiba Mitsubishi-Electric Industrial Systems Corporation, Kobe International Business Center (KIBC) 509, 5-5-2 Minatojima-Minami, Chuo-Ku, Kobe 650-0047 (Japan)

    2015-12-31

    Atmospheric pressure mist chemical vapor deposition (Mist–CVD) systems have been developed to grow zinc-oxide-based (ZnO-based) transparent conductive oxide (TCO) films. Low-resistive aluminum-doped ZnO (AZO) TCOs, showing resistivity of the order on 10{sup −4} Ωcm, previously were grown using a safe source material zinc acetate [Zn(ac){sub 2}], at a growth temperature as high as 500 °C. To grow superior TCOs at lower temperatures, we proposed the addition of NH{sub 3} to accelerate the reaction of acetylacetonate compounds. As the result, we could grow gallium-doped ZnO (GZO) TCOs with a resistivity of 2.7 × 10{sup −3} Ω cm and transmittance higher than 90% at 300 °C by using zinc acetylacetonate [Zn(acac){sub 2}] as the Zn source. To grow boron-doped ZnO (BZO) TCOs at a lower growth temperature of 200 °C, we used boron doping along with a toluene solution of diethylzinc (DEZ), that maintained high reactivity without being flammable. These BZO TCOs showed a resistivity of 1.5 × 10{sup −3} Ω cm and transmittance higher than 90%, despite the use of a non-vacuum-based open-air technology. - Highlights: • Introduction of Mist–CVD as a non-vacuum-based, safe, and cost-effective growth technology • Process evolution of the growth technology to lower the growth temperature. • Achievement of low resistive ZnO films at 200oC.

  2. High temperature thermodynamics and vaporization of the zirconium--niobium--oxygen system

    International Nuclear Information System (INIS)

    Rinehart, G.H.

    1978-01-01

    The vaporization behavior of the Zr--Nb--O system was studied by means of successive vaporization, Knudsen effusion-target collection experiments, and mass spectrometric analysis of the vapors effusing from a Knudsen crucible. The successive vaporization experiments were performed on two ternary samples in open crucibles. X-ray powder diffraction patterns of the residues and x-ray fluorescence analysis of the condensates and residues indicated the preferential vaporization of niobium-containing species with the composition of the residue subsequently becoming closer to that of congruently vaporizing ZrO/sub 2-x/. The Knudsen effusion-target collection experiments were employed on two samples, pure NbO 2 (s) and a two-phase ZrO 2 --NbO 2 mixture, in order to obtain information on the activity of NbO 2 in the two-phase mixture. Second law enthalpies and entropies of sublimation as well as third law enthalpies were obtained for both systems. The vaporization behaviors of five compositions in the Zr--Nb--O system, NbO 2 , NbO, a ZrO 2 --NbO 2 two-phase mixture, Nb 2 O 5 , and Zr 6 Nb 2 O 17 , were investigated. Above Nb 2 O 5 and the fully oxidized Zr 6 Nb 2 O 17 oxygen is preferentially lost; over NbO 2 , the two-phase ZrO 2 --NbO 2 system, and NbO the principal gaseous species is NbO 2

  3. Microwave and Millimeter-Wave Radiometric Studies of Temperature, Water Vapor and Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Westwater, Edgeworth

    2011-05-06

    The importance of accurate measurements of column amounts of water vapor and cloud liquid has been well documented by scientists within the Atmospheric Radiation Measurement (ARM) Program. At the North Slope of Alaska (NSA), both microwave radiometers (MWR) and the MWRProfiler (MWRP), been used operationally by ARM for passive retrievals of the quantities: Precipitable Water Vapor (PWV) and Liquid Water Path (LWP). However, it has been convincingly shown that these instruments are inadequate to measure low amounts of PWV and LWP. In the case of water vapor, this is especially important during the Arctic winter, when PWV is frequently less than 2 mm. For low amounts of LWP (< 50 g/m{sup 2}), the MWR and MWRP retrievals have an accuracy that is also not acceptable. To address some of these needs, in March-April 2004, NOAA and ARM conducted the NSA Arctic Winter Radiometric Experiment - Water Vapor Intensive Operational Period at the ARM NSA/Adjacent Arctic Ocean (NSA/AAO) site. After this experiment, the radiometer group at NOAA moved to the Center for Environmental Technology (CET) of the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. During this 2004 experiment, a total of 220 radiosondes were launched, and radiometric data from 22.235 to 380 GHz were obtained. Primary instruments included the ARM MWR and MWRP, a Global Positioning System (GPS), as well as the CET Ground-based Scanning Radiometer (GSR). We have analyzed data from these instruments to answer several questions of importance to ARM, including: (a) techniques for improved water vapor measurements; (b) improved calibration techniques during cloudy conditions; (c) the spectral response of radiometers to a variety of conditions: clear, liquid, ice, and mixed phase clouds; and (d) forward modeling of microwave and millimeter wave brightness temperatures from 22 to 380 GHz. Many of these results have been published in the open literature. During the third year of

  4. Nuclear criticality safety aspects of gaseous uranium hexafluoride (UF{sub 6}) in the diffusion cascade

    Energy Technology Data Exchange (ETDEWEB)

    Huffer, J.E. [Parallax, Inc., Atlanta, GA (United States)

    1997-04-01

    This paper determines the nuclear safety of gaseous UF{sub 6} in the current Gaseous Diffusion Cascade and auxiliary systems. The actual plant safety system settings for pressure trip points are used to determine the maximum amount of HF moderation in the process gas, as well as the corresponding atomic number densities. These inputs are used in KENO V.a criticality safety models which are sized to the actual plant equipment. The ENO V.a calculation results confirm nuclear safety of gaseous UF{sub 6} in plant operations..

  5. UF6 Density and Mass Flow Measurements for Enrichment Plants using Acoustic Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Good, Morris S.; Smith, Leon E.; Warren, Glen A.; Jones, Anthony M.; Ramuhalli, Pradeep; Roy, Surajit; Moran, Traci L.; Denslow, Kayte M.; Longoni, Gianluca

    2017-09-01

    A key enabling capability for enrichment plant safeguards being considered by the International Atomic Energy Agency (IAEA) is high-accuracy, noninvasive, unattended measurement of UF6 gas density and mass flow rate. Acoustic techniques are currently used to noninvasively monitor gas flow in industrial applications; however, the operating pressures at gaseous centrifuge enrichment plants (GCEPs) are roughly two orders magnitude below the capabilities of commercial instrumentation. Pacific Northwest National Laboratory is refining acoustic techniques for estimating density and mass flow rate of UF6 gas in scenarios typical of GCEPs, with the goal of achieving 1% measurement accuracy. Proof-of-concept laboratory measurements using a surrogate gas for UF6 have demonstrated signatures sensitive to gas density at low operating pressures such as 10–50 Torr, which were observed over the background acoustic interference. Current efforts involve developing a test bed for conducting acoustic measurements on flowing SF6 gas at representative flow rates and pressures to ascertain the viability of conducting gas flow measurements under these conditions. Density and flow measurements will be conducted to support the evaluation. If successful, the approach could enable an unattended, noninvasive approach to measure mass flow in unit header pipes of GCEPs.

  6. Ultras-stable Physical Vapor Deposited Amorphous Teflon Films with Extreme Fictive Temperature Reduction

    Science.gov (United States)

    McKenna, Gregory; Yoon, Heedong; Koh, Yung; Simon, Sindee

    In the present work, we have produced highly stable amorphous fluoropolymer (Teflon AF® 1600) films to study the calorimetric and relaxation behavior in the deep in the glassy regime. Physical vapor deposition (PVD) was used to produce 110 to 700 nm PVD films with substrate temperature ranging from 0.70 Tg to 0.90 Tg. Fictive temperature (Tf) was measured using Flash DSC with 600 K/s heating and cooling rates. Consistent with prior observations for small molecular weight glasses, large enthalpy overshoots were observed in the stable amorphous Teflon films. The Tf reduction for the stable Teflon films deposited in the vicinity of 0.85 Tg was approximately 70 K compared to the Tgof the rejuvenated system. The relaxation behavior of stable Teflon films was measured using the TTU bubble inflation technique and following Struik's protocol in the temperature range from Tf to Tg. The results show that the relaxation time decreases with increasing aging time implying that devitrification is occurring in this regime.

  7. Micron-sized columnar grains of CH3NH3PbI3 grown by solvent-vapor assisted low-temperature (75 °C) solid-state reaction: The role of non-coordinating solvent-vapor

    Science.gov (United States)

    Zheng, Huifeng; Liu, Yangqiao; Sun, Jing

    2018-04-01

    The preparation of hybrid perovskite films with large columnar grains via low-temperature solid-state reaction remains a big challenge. Conventional solvent annealing using DMF, DMSO and ethanol, etc. fails to work effectively at low temperature (solar cells based on benzyl-alcohol-vapor annealing (75 °C), delivered much higher photovoltaic performance, better stability and smaller hysteresis than those based on conventional thermal annealing. Additionally, a champion power conversion efficiency (PCE) of 15.1% was obtained and the average PCE reached 12.2% with a tiny deviation. Finally, the mechanism of solvent annealing with non-coordinating solvent was discussed. Moreover, we revealed that high polarity and high boiling point of the solvent used for generating vapor, was critical to grow micron-sized columnar grains at such a low temperature (75 °C). This work will contribute to understanding the mechanism of grain growth in solvent annealing and improving its facility and effectiveness.

  8. Examination of the Effects of Activated Carbon Produced from Coal Using Single-Step H3PO4/N2+H2O Vapor Activation on the Adsorption of Bovine Serum Albumin at Different Temperatures and pH Values

    Directory of Open Access Journals (Sweden)

    Atakan Toprak

    2017-12-01

    Full Text Available This study examined protein adsorption equilibrium and kinetics on activated carbon (AC that we obtained from coal by single-step H3PO4 activation under N2+H2O vapor at 800 °C. Surface properties, pore size distribution, and volumes of AC were determined using the volumetric method with N2 adsorption at 77 K. Also, the textural properties were characterized by SEM-EDAX and XRD. The zeta potential values were measured to elucidate the electrostatic interactions between the protein and AC. The obtained AC discrete system was also used as an adsorbent for adsorbing bovine serum albumin (BSA from aqueous solution. The effects of pH (4.0, 5.0, and 7.4 and temperatures (20, 30 and 40 °C on the adsorption of BSA on AC were examined. The surface area, micropore, mesopore and total pore volumes of AC were found to be 1175 m2/g, 0.477 cm3/g, 0.061 cm3/g and 0.538 cm3/g, respectively. The optimum temperature for AC in BSA adsorption was found to be 40 °C and the pH was found to be 4.0. The highest BSA adsorption was found to be 159 mg/g and pH to be 4.0. The experimental equilibrium data were compared with the Langmuir and Freundlich models and found to be compatible with both models. The adsorption process is best described by the pseudo-first-order kinetic model. As a result, it was found out that AC obtained by single step H3PO4/N2+H2O vapor activation is an effective adsorbent for the adsorption of BSA from aqueous solution.

  9. A vapor feed methanol microfluidic fuel cell with high fuel and energy efficiency

    International Nuclear Information System (INIS)

    Wang, Yifei; Leung, Dennis Y.C.; Xuan, Jin; Wang, Huizhi

    2015-01-01

    Highlights: • A microfluidic fuel cell with a vapor feed anode is investigated. • Its advantages include simpler design, direct usage of methanol and better performance. • The prototype achieves a peak power density of 55.4 mW cm −2 under room temperature. • The energy efficiency of 9.4% is much higher than its liquid feed counterpart. - Abstract: In this paper, a prototype of methanol microfluidic fuel cell with vapor feed anode configuration is proposed to improve the fuel and energy efficiency of the conventional liquid feed methanol microfluidic fuel cells. Peak power density of 55.4 mW cm −2 can be achieved with this prototype under room temperature, which is 30% higher than its conventional liquid feed counterpart. Moreover, an energy efficiency of 9.4% is achieved, which is 27.5 times higher than its liquid feed counterpart. This superiority on both cell performance and energy efficiency is directly benefitted from its vapor feed anode configuration, which alleviates the fuel crossover, eliminates the fuel depletion boundary layer, and avoids the bulk anolyte wastage. The tradeoff between cell performance and fuel utilization for conventional liquid feed microfluidic fuel cells is also evaded

  10. Laboratory and pilot-plant studies on the conversion of uranyl nitrate hexahydrate to UF/sub 6/ by fluidized-bed processes

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, E.L.; Urza, I.J.; Cathers, G.I.

    1977-06-01

    This report describes laboratory and pilot-plant studies on the conversion of uranyl nitrate hexahydrate (UNH) to UF/sub 6/ and on purification of the UF/sub 6/. Experimental laboratory studies on the removal of residual nitrate from uranium trioxide (UO/sub 3/) calcine and the fluorination of technetium and subsequent sorption on MgF/sub 2/ were conducted to support the pilot-plant work. Two engineering-scale pilot plants utilizing fluidized-bed processes were constructed for equipment and process testing of the calcination of UNH to UO/sub 3/ and the direct fluorination of UO/sub 3/ to UF/sub 6/.

  11. Prediction of vapor pressure and heats of vaporization of edible oil/fat compounds by group contribution

    DEFF Research Database (Denmark)

    Ceriani, Roberta; Gani, Rafiqul; Liu, Y.A.

    2013-01-01

    In the present work, a group contribution method is proposed for the estimation of vapor pressures and heats of vaporization of organic liquids found in edible fat/oil and biofuel industries as a function of temperature. The regression of group contribution parameters was based on an extensive...

  12. Medicinal Cannabis: In Vitro Validation of Vaporizers for the Smoke-Free Inhalation of Cannabis.

    Directory of Open Access Journals (Sweden)

    Christian Lanz

    Full Text Available Inhalation by vaporization is a promising application mode for cannabis in medicine. An in vitro validation of 5 commercial vaporizers was performed with THC-type and CBD-type cannabis. Gas chromatography/mass spectrometry was used to determine recoveries of total THC (THCtot and total CBD (CBDtot in the vapor. High-performance liquid chromatography with photodiode array detection was used for the quantitation of acidic cannabinoids in the residue and to calculate decarboxylation efficiencies. Recoveries of THCtot and CBDtot in the vapor of 4 electrically-driven vaporizers were 58.4 and 51.4%, 66.8 and 56.1%, 82.7 and 70.0% and 54.6 and 56.7% for Volcano Medic®, Plenty Vaporizer®, Arizer Solo® and DaVinci Vaporizer®, respectively. Decarboxylation efficiency was excellent for THC (≥ 97.3% and CBD (≥ 94.6%. The gas-powered Vape-or-Smoke™ showed recoveries of THCtot and CBDtot in the vapor of 55.9 and 45.9%, respectively, and a decarboxylation efficiency of ≥ 87.7 for both cannabinoids. However, combustion of cannabis was observed with this device. Temperature-controlled, electrically-driven vaporizers efficiently decarboxylate inactive acidic cannabinoids and reliably release their corresponding neutral, active cannabinoids. Thus, they offer a promising application mode for the safe and efficient administration of medicinal cannabis.

  13. Raman Investigation of The Uranium Compounds U3O8, UF4, UH3 and UO3 under Pressure at Room Temperature

    International Nuclear Information System (INIS)

    Lipp, M.J.; Jenei, Z.; Park-Klepeis, J.; Evans, W.J.

    2011-01-01

    Our current state-of-the-art X-ray diffraction experiments are primarily sensitive to the position of the uranium atom. While the uranium - low-Z element bond (such as U-H or U-F) changes under pressure and temperature the X-ray diffraction investigations do not reveal information about the bonding or the stoichiometry. Questions that can be answered by Raman spectroscopy are (i) whether the bonding strength changes under pressure, as observed by either blue- or red-shifted peaks of the Raman active bands in the spectrum and (ii) whether the low-Z element will eventually be liberated and leave the host lattice, i.e. do the fluorine, oxygen, or hydrogen atoms form dimers after breaking the bond to the uranium atom. Therefore Raman spectra were also collected in the range where those decomposition products would appear. Raman is particularly well suited to these types of investigations due to its sensitivity to trace amounts of materials. One challenge for Raman investigations of the uranium compounds is that they are opaque to visible light. They absorb the incoming radiation and quickly heat up to the point of decomposition. This has been dealt with in the past by keeping the incoming laser power to very low levels on the tens of milliWatt range consequently affecting signal to noise. Recent modern investigations also used very small laser spot sizes (micrometer range) but ran again into the problem of heating and chemical sensitivity to the environment. In the studies presented here (in contrast to all other studies that were performed at ambient conditions only) we employ micro-Raman spectroscopy of samples situated in a diamond anvil cell. This increases the trustworthiness of the obtained data in several key-aspects: (a) We surrounded the samples in the DAC with neon as a pressure transmitting medium, a noble gas that is absolutely chemically inert. (b) Through the medium the sample is thermally heat sunk to the diamond anvils, diamond of course possessing the

  14. Liquid-vapor equilibrium and interfacial properties of square wells in two dimensions

    Science.gov (United States)

    Armas-Pérez, Julio C.; Quintana-H, Jacqueline; Chapela, Gustavo A.

    2013-01-01

    Liquid-vapor coexistence and interfacial properties of square wells in two dimensions are calculated. Orthobaric densities, vapor pressures, surface tensions, and interfacial thicknesses are reported. Results are presented for a series of potential widths λ* = 1.4, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5, where λ* is given in units of the hard core diameter σ. Critical and triple points are explored. No critical point was found for λ* Armas-Pérez et al. [unpublished] as a hexatic phase transition. It is located at reduced temperatures T* = 0.47 and 0.35 for λ* = 1.4 and 1.5, respectively. Properties such as the surface tension, vapor pressure, and interfacial thickness do not present any discontinuity at these points. This amorphous solid branch does not follow the corresponding state principle, which is only applied to liquids and gases.

  15. Chemistry of gaseous lower halides of uranium. Technical progress report, 1 September 1979-1 April 1980

    International Nuclear Information System (INIS)

    Hildenbrand, D.L.

    1980-01-01

    The gaseous uranium species UF, UF 2 , UF 3 , and UF 4 were generated in effusion cell beams by vaporization of UF 4 (s) under reducing conditions, and they were identified and studied by mass spectrometry. From extensive second-law studies of reaction equilibria involving these species and several reaction partners used as reference standards, the individual bond dissociation energies and standard enthalpies of formation of the U-F species were derived. Reaction entropies derived from the slope data indicate that the electronic entropies of the U-F species are substantial, and are comparable to or larger than that of atomic uranium. Additional thermochemical measurements were made to establish the properties of several Ag and Cu monohalides that have been or will be used as reference standards in the uranium halide measurements. From studies of the sublimation and decomposition of uranyl fluoride, UO 2 F 2 (s), the enthalpy of sublimation of UO 2 F 2 (g), has been determined, and another gaseous oxyfluoride, UOF 4 (g), has been tentatively identified. The gaseous products of decomposition of UO 2 F 2 (s) observed by mass spectrometry differ from those postulated by other investigators, indicating that the mechanism of decomposition has not been clearly established. A search of the thermochemical literature on uranium halides has been completed

  16. Unsaturated zone moisture and vapor movement induced by temperature variations in asphalt barrier field lysimeters

    International Nuclear Information System (INIS)

    Holford, D.J.; Fayer, M.J.

    1990-08-01

    Protective barriers are being considered for use at the Hanford Site to enhance the isolation of radioactive wastes from water, plant, and animal intrusion. Lysimeters were constructed to evaluate the performance of asphalt barrier formulations under natural environmental conditions. These lysimeters were constructed of 1.7-m lengths of PVC pipe that have a diameter of 30 cm. The lysimeters were filled with layers of gravel, coarse sand, and asphalt. The sand and gravel placed under the asphalt barrier were wet when installed. TOUGH was used to conduct simulations to assess the effect of temperature variations on moisture and vapor movement beneath the asphalt layer in field test lysimeters. All variables in TOUGH were converted to double precision so that simulations could be run on a Sun-4 UNIX workstation. A radially symmetric grid was used to simulate the lysimeter. 8 refs., 9 figs

  17. Scoping study to expedite development of a field deployable and portable instrument for UF6 enrichment assay

    OpenAIRE

    Chan, CYG; Valentine, JD; Russo, RE

    2017-01-01

    The primary objective of the present study is to identity the most promising, viable technologies that are likely to culminate in an expedited development of the next-generation, field-deployable instrument for providing rapid, accurate, and precise enrichment assay of uranium hexafluoride (UF6). UF6 is typically involved, and is arguably the most important uranium compound, in uranium enrichment processes. As the first line of defense against proliferation, accurate analytical techniques t...

  18. Sampling and characterization of aerosols formed in the atmospheric hydrolysis of UF6

    International Nuclear Information System (INIS)

    Bostick, W.D.; McCulla, W.H.; Pickrell, P.W.; Branam, D.A.

    1983-01-01

    When gaseous UF 6 is released into the atmosphere, it rapidly reacts with ambient moisture to form an aerosol of uranyl fluoride and HF. As part of our Safety Analysis program, we have performed several experimental releases of UF 6 (from natural uranium) in contained volumes in order to investigate techniques for sampling and characterizing the aerosol materials. The aggregrate particle morphology and size distribution have been found to be dependent upon several conditions, including the relative humidity at the time of the release and the elapse time after the release. Aerosol composition and settling rate have been investigated using isokinetic samplers for the separate collection of UO 2 F 2 and HF, and via laser spectroscopic remote sensing (Mie scatter and infrared spectroscopy). 8 references

  19. Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films

    DEFF Research Database (Denmark)

    Sarkar, I.; Laux, M.; Demokritova, J.

    2010-01-01

    We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth...... of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method....

  20. CH3NH3I treatment temperature of 70 °C in low-pressure vapor-assisted deposition for mesoscopic perovskite solar cells

    Science.gov (United States)

    Jin, Wenbin; Zou, Xiaoping; Bai, Xiao; Yang, Ying; Chen, Dan

    2018-01-01

    Herein, we report a modified vapor-assisted deposition method to fabricate CH3NH3PbI3 film at 70 °C in a vacuum drying oven. The modified method has excellent operability and expandability in preparing perovskite solar cells. The CH3NH3I treatment temperature is 130 °C or 150 °C in conventional method, but we reduced the temperature to 70 °C in the modified vapor-assisted method. Meanwhile, the quality of CH3NH3PbI3 films prepared via the modified method is superior to that of CH3NH3PbI3 films of solution-processed method.

  1. Single-resonance optical pumping spectroscopy and application in dressed-state measurement with atomic vapor cell at room temperature.

    Science.gov (United States)

    Liang, Qiangbing; Yang, Baodong; Zhang, Tiancai; Wang, Junmin

    2010-06-21

    By monitoring the transmission of probe laser beam (also served as coupling laser beam) which is locked to a cycling hyperfine transition of cesium D(2) line, while pumping laser is scanned across cesium D(1) or D(2) lines, the single-resonance optical pumping (SROP) spectra are obtained with atomic vapor cell. The SROP spectra indicate the variation of the zero-velocity atoms population of one hyperfine fold of ground state, which is optically pumped into another hyperfine fold of ground state by pumping laser. With the virtue of Doppler-free linewidth, high signal-to-noise ratio (SNR), flat background and elimination of crossover resonance lines (CRLs), the SROP spectra with atomic vapor cell around room temperature can be employed to measure dressed-state splitting of ground state, which is normally detected with laser-cooled atomic sample only, even if the dressed-state splitting is much smaller than the Doppler-broaden linewidth at room temperature.

  2. Analysis of potassium nitrate purification with recovery of solvent through single effect mechanical vapor compression

    Directory of Open Access Journals (Sweden)

    Kiprotich E. Kosgey

    2017-12-01

    Full Text Available Analysis of purification of potassium nitrate with incorporation of single effect mechanical vapor compressor for solvent recovery was done. Analysis focused on the effect of concentration and temperature of mother liquor on the energy efficiency of the process and the amount of recovered solvent. Performance coefficient of mechanical vapor compressor ranged between 1.5 and 7.5 depending primarily on the temperature of mother liquor. It was found that with increase in temperature of mother liquor through pre-heating, the power of the compressor, compression ratio and amount of heat supplied to the evaporator decrease. For a 40% concentrated feed solution and mother liquor temperature above 80 °C, performance coefficient is higher than 4. It is therefore concluded that preheating mother liquor and reduction of the effect of concentration of both mother liquor and concentrated waste stream through other methods reduces the power consumption of purification process. Keywords: Performance coefficient, Mother liquor, Concentrated solution, Recovered solvent, Boiling point elevation, Mechanical vapor compressor

  3. Vapor flux and recrystallization during dry snow metamorphism under a steady temperature gradient as observed by time-lapse micro-tomography

    Directory of Open Access Journals (Sweden)

    B. R. Pinzer

    2012-10-01

    Full Text Available Dry snow metamorphism under an external temperature gradient is the most common type of recrystallization of snow on the ground. The changes in snow microstructure modify the physical properties of snow, and therefore an understanding of this process is essential for many disciplines, from modeling the effects of snow on climate to assessing avalanche risk. We directly imaged the microstructural changes in snow during temperature gradient metamorphism (TGM under a constant gradient of 50 K m−1, using in situ time-lapse X-ray micro-tomography. This novel and non-destructive technique directly reveals the amount of ice that sublimates and is deposited during metamorphism, in addition to the exact locations of these phase changes. We calculated the average time that an ice volume stayed in place before it sublimated and found a characteristic residence time of 2–3 days. This means that most of the ice changes its phase from solid to vapor and back many times in a seasonal snowpack where similar temperature conditions can be found. Consistent with such a short timescale, we observed a mass turnover of up to 60% of the total ice mass per day. The concept of hand-to-hand transport for the water vapor flux describes the observed changes very well. However, we did not find evidence for a macroscopic vapor diffusion enhancement. The picture of {temperature gradient metamorphism} produced by directly observing the changing microstructure sheds light on the micro-physical processes and could help to improve models that predict the physical properties of snow.

  4. Experimental study of vapor explosion of molten salt and low boiling point liquid

    International Nuclear Information System (INIS)

    Iida, Yoshihiro; Takashima, Takeo

    1987-01-01

    Fundamental study of vapor explosion using small drops of high temperature liquid and low boiling point liquid and a series of small-scale vapor explosion tests are carried out. A single or plural drops of molten LiNO 3 are dropped into ethyl alcohol and the temperature range of two liquids wherein the fragmentation occurs is examined. The propagation phenomenon of vapor explosion between two drops is photographed and the pressure trace is proved to be well consistent with the behavior of the vapor bubble regions. A small amount of molten Flinak and tin which are enclosed in a test tube is dropped into tapped water. The temperature effect of two liquids onto the occurrence of vapor explosion is investigated. Some considerations are made with respect to the upper and lower temperature limits of vapor explosion to occur. A qualitative modeling of vapor explosion mechanism is proposed and discussed. (author)

  5. Behavior of UO2 and FISSIUM in sodium vapor atmosphere at temperatures up to 28000C

    International Nuclear Information System (INIS)

    Feuerstein, H.; Oschinski, J.

    1986-11-01

    In case of a HCDA a rubble bed of fuel debris may form under a sodium pool and reach high temperatures. An experimental technique was developed to study the behavior of fuel and fission products in out-of-pile tests in a sodium vapor atmosphere. Evaporation rates of UO 2 were measured up to 2800 0 C. The evaporation was found to be a complex process, depending on temperature and the 'active' surface. Evaporation restructures the surface of the samples, however no new 'active' surface is formed. UO 2 forms sometimes well shaped crystals and curious erosion products. The efficiency of the used condenser/filter lines was higher than 99.99%. In case of a HCDA all the evaporated substances will condense in the soidum pool. Thermal reduction of the UO 2 reduces the oxygen potential of the system. The final composition at 2500 0 C was found to be UO 1.95 . The only influence of the sodium vapor was found for the diffusion of UO 2 into the thoria of the crucible. Compared with experiments in an atmosphere of pure argon, the diffusion rate was reduced. (orig.) [de

  6. Removal of a synthetic organic chemical by PAC-UF systems. II: Model application.

    Science.gov (United States)

    Matsui, Y; Colas, F; Yuasa, A

    2001-02-01

    This paper describes several application potentials with a recently developed model for predicting the synthetic organic chemical (SOC) removal by powdered activated carbon (PAC) adsorption during ultrafiltration (UF) and discusses the removal mechanism. The model was successfully applied, without any modification, to dead-end mode operation as well as to cross-flow mode operation, validating the assumption of the internal diffusion control mechanism and the continuously-stirred-tank-reactor (CSTR) concept. Even when UF was operated in a cross-flow mode, PAC added was re-circulating in suspension for only a short time. Then, solute uptake took place mostly by PAC immobilized in membrane tubes not only for dead-end operation but also for cross-flow operation. Therefore, cross-flow operation did not have any advantage regarding the SOC mass transfer on PAC in UF loop over dead-end operation. The model simulation implied that pulse PAC addition at the beginning of filtration cycle resulted better SOC removal than continuous PAC addition. However, for the pulse PAC addition mode, the model predicted somewhat lower effluent SOC concentration than the observed values, and the benefit of pulse PAC application in terms of reducing SOC over its continuous dosage was not confirmed. Longer detention time of PAC dosed in a pulse than continuously dosed PAC could possibly further decrease internal diffusivity.

  7. The effect of molten salt on high temperature behavior of stainless steel and titanium alloy with the presence of water vapor

    Science.gov (United States)

    Baharum, Azila; Othman, Norinsan Kamil; Salleh, Emee Marina

    2018-04-01

    The high temperature oxidation experiment was conducted to study the behavior of titanium alloy Ti6A14V and stainless steel 316 in Na2SO4-50%NaCl + Ar-20%O2 (molten salt) and Na2SO4-50%NaCl + Ar-20%O2 + 12% H2O (molten salt + water vapor) environment at 900°C for 30 hours using horizontal tube furnace. The sample then was investigated using weight change measurement analysis and X-ray diffraction (XRD) analysis to study the weight gained and the phase oxidation that occurred. The weight gained of the titanium alloy was higher in molten salt environment compared to stainless steel due to the rapid growth in the oxide scale but showed almost no change of weight gained upon addition of water vapor. This is due to the alloy was fully oxidized. Stainless steel showed more protection and better effect in molten salt environment compared to mixed environment showed by slower weight gain and lower oxidation rate. Meanwhile, the phase oxidation test of the samples showed that the titanium alloy consist of multi oxide layer of rutile (TiO2) and Al2O3 on the surface of the exposed sample. While stainless steel show the formation of both protective Cr-rich oxide and non-protective Fe-rich oxide layer. This can be concluded that stainless steel is better compared to Ti alloy due to slow growing of chromia oxide. Therefore it is proven that stainless steel has better self-protection upon high temperature exposure.

  8. Single-photon cesium Rydberg excitation spectroscopy using 318.6-nm UV laser and room-temperature vapor cell.

    Science.gov (United States)

    Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

    2017-09-18

    We demonstrate a single-photon Rydberg excitation spectroscopy of cesium (Cs) atoms in a room-temperature vapor cell. Cs atoms are excited directly from 6S 1/2 ground state to nP 3/2 (n = 70 - 100) Rydberg states with a 318.6 nm ultraviolet (UV) laser, and Rydberg excitation spectra are obtained by transmission enhancement of a probe beam resonant to Cs 6S 1/2 , F = 4 - 6P 3/2 , F' = 5 transition as partial population on F = 4 ground state are transferred to Rydberg state. Analysis reveals that the observed spectra are velocity-selective spectroscopy of Rydberg state, from which the amplitude and linewidth influenced by lasers' Rabi frequency have been investigated. Fitting to energies of Cs nP 3/2 (n = 70 -100) states, the determined quantum defect is 3.56671(42). The demodulated spectra can also be employed as frequency references to stabilize the UV laser frequency to specific Cs Rydberg transition.

  9. 33 CFR 154.826 - Vapor compressors and blowers.

    Science.gov (United States)

    2010-07-01

    ...) Excessive shaft bearing temperature. (d) If a centrifugal compressor, fan, or lobe blower handles vapor in... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vapor compressors and blowers....826 Vapor compressors and blowers. (a) Each inlet and outlet to a compressor or blower which handles...

  10. Electron beam physical vapor deposition of thin ruby films for remote temperature sensing

    International Nuclear Information System (INIS)

    Li Wei; Coppens, Zachary J.; Greg Walker, D.; Valentine, Jason G.

    2013-01-01

    Thermographic phosphors (TGPs) possessing temperature-dependent photoluminescence properties have a wide range of uses in thermometry due to their remote access and large temperature sensitivity range. However, in most cases, phosphors are synthesized in powder form, which prevents their use in high resolution micro and nanoscale thermal microscopy. In the present study, we investigate the use of electron beam physical vapor deposition to fabricate thin films of chromium-doped aluminum oxide (Cr-Al 2 O 3 , ruby) thermographic phosphors. Although as-deposited films were amorphous and exhibited weak photoluminescence, the films regained the stoichiometry and α-Al 2 O 3 crystal structure of the combustion synthesized source powder after thermal annealing. As a consequence, the annealed films exhibit both strong photoluminescence and a temperature-dependent lifetime that decreases from 2.9 ms at 298 K to 2.1 ms at 370 K. Ruby films were also deposited on multiple substrates. To ensure a continuous film with smooth surface morphology and strong photoluminescence, we use a sapphire substrate, which is thermal expansion coefficient and lattice matched to the film. These thin ruby films can potentially be used as remote temperature sensors for probing the local temperatures of micro and nanoscale structures.

  11. 40 CFR 796.1950 - Vapor pressure.

    Science.gov (United States)

    2010-07-01

    ... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a.... In addition, chemicals that are likely to be gases at ambient temperatures and which have low water... gases until the measured vapor pressure is constant, a process called “degassing.” Impurities more...

  12. Vapor pumps and gas-driven machines

    International Nuclear Information System (INIS)

    Guillet, R.

    1991-01-01

    The vapor pump, patented in 1979 by Gaz de France, is an additional mass and heat exchanger which uses the combustion air of fuel-burning machines as an additional cold source. This cold source is preheated and, above all, humidified before reaching the burner, by means of the residual sensible and latent heat in the combustion products of the fuel-burning process. This final exchanger thus makes it possible, in many cases, to recover all the gross calorific value of natural gas, even when the combustion products leave the process at a wet temperature greater than 60 0 C, the maximum dew point of the products of normal combustion. Another significant advantage of the vapor pump being worth highlighting is the selective recycling of water vapor by the vapor pump which reduces the adiabatic combustion temperature and the oxygen concentration in the combustion air, two factors which lead to considerable reductions in nitrogen oxides formation, hence limiting atmospheric pollution. Alongside a wide range of configurations which make advantageous use of the vapor pump in association with gas-driven machines and processes, including gas turbines, a number of boiler plant installations are also presented [fr

  13. Storage and uses alternatives of depleted UF6

    International Nuclear Information System (INIS)

    Marques, S.; Dotto, R.M.

    1988-01-01

    The U-enrichment of the Angra-1 pellets (Brazil) have generated about 792 ton of depleted-U, which is nowadays beeing stored by URENCO. The possible sending of this compound to Brazil, added to the fact that in the future, NUCLEI (Nuclebras Enriquecimento Isotopico) itself will generate it, reopens the discussion of the destination of this compound. In this context, the necessity, interest and viability aspects of a reconvertion plant of UF 6 in Brazil are getting important and are, in what follows, breafly discussed. (author) [pt

  14. Development of a hybrid refrigerator combining thermoelectric and vapor compression technologies

    International Nuclear Information System (INIS)

    Vian, J.G.; Astrain, D.

    2009-01-01

    A domestic refrigerator with three compartments has been developed: refrigerator compartment, at 4 deg. C (vapor compression cooling system); freezer compartment, at -22 deg. C (vapor compression cooling system); and a new super-conservation compartment, at 0 deg. C (thermoelectric cooling system). The thermoelectric system designed for the super-conservation compartment eliminates the oscillation of its temperature due to the start and stop compressor cycles, obtaining a constant temperature and thus, a better preservation of the food. For the design and optimization of this application, a computational model, based in the numerical method of finite differences, has been developed. This model allows to simulate the complete hybrid refrigerator (vapor compression-thermoelectricity). The accuracy of the model has been experimentally checked, with a maximum error of 1.2 deg. C for temperature values, and 8% for electric power consumption. By simulations with the computational model, the design of the refrigerator has been optimized, obtaining a final prototype highly competitive, by the features on food preservation and power consumption: 1.15 kW h per day (48.1 W) for an ambient temperature of 25 deg. C. According to European rules, this power consumption value means that this new refrigerator could be included on energy efficiency class B.

  15. Accurate measurements and temperature dependence of the water vapor self-continuum absorption in the 2.1 μm atmospheric window

    International Nuclear Information System (INIS)

    Ventrillard, I.; Romanini, D.; Mondelain, D.; Campargue, A.

    2015-01-01

    In spite of its importance for the evaluation of the Earth radiative budget, thus for climate change, very few measurements of the water vapor continuum are available in the near infrared atmospheric windows especially at temperature conditions relevant for our atmosphere. In addition, as a result of the difficulty to measure weak broadband absorption signals, the few available measurements show large disagreements. We report here accurate measurements of the water vapor self-continuum absorption in the 2.1 μm window by Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) for two spectral points located at the low energy edge and at the center of the 2.1 μm transparency window, at 4302 and 4723 cm −1 , respectively. Self-continuum cross sections, C S , were retrieved with a few % relative uncertainty, from the quadratic dependence of the spectrum base line level measured as a function of water vapor pressure, between 0 and 16 Torr. At 296 K, the C S value at 4302 cm −1 is found 40% higher than predicted by the MT-CKD V2.5 model, while at 4723 cm −1 , our value is 5 times larger than the MT-CKD value. On the other hand, these OF-CEAS C S values are significantly smaller than recent measurements by Fourier transform spectroscopy at room temperature. The temperature dependence of the self-continuum cross sections was also investigated for temperatures between 296 K and 323 K (23-50 °C). The derived temperature variation is found to be similar to that derived from previous Fourier transform spectrometer (FTS) measurements performed at higher temperatures, between 350 K and 472 K. The whole set of measurements spanning the 296-472 K temperature range follows a simple exponential law in 1/T with a slope close to the dissociation energy of the water dimer, D 0 ≈ 1100 cm −1

  16. Observation and particle simulation of vaporized W, Mo, and Be in PISCES-B plasma for vapor-shielding studies

    Directory of Open Access Journals (Sweden)

    K. Ibano

    2017-08-01

    Full Text Available Interactions of Tungsten (W, Molybdenum (Mo, and Beryllium (Be vapors with a steady-state plasma were studied by the PISCES-B liner plasma experiments as well as Particle-In-Cell (PIC simulations for the understanding of vapor-shielding phenomena. Effective cooling of the plasma by laser-generated Be vapor was observed in PISCES-B. On the other hand, no apparent cooling was observed for W and Mo vapors. The PIC simulation explains these experimental observations of the difference between low-Z and high-Z vapors. Decrease of electron temperature due to the vapor ejection was observed in case of a simulation of the Be vapor. As for the W vapor, it was found that the plasma cooling is localized only near the wall at a higher electron density plasma (∼1019m−3. On the other hand, the appreciable plasma cooling can be observed in a lower density plasma (∼1018m−3 for the W vapor.

  17. GeSn growth kinetics in reduced pressure chemical vapor deposition from Ge2H6 and SnCl4

    Science.gov (United States)

    Aubin, J.; Hartmann, J. M.

    2018-01-01

    We have investigated the low temperature epitaxy of high Sn content GeSn alloys in a 200 mm industrial Reduced Pressure - Chemical Vapor Deposition tool from Applied Materials. Gaseous digermane (Ge2H6) and liquid tin tetrachloride (SnCl4) were used as the Ge and Sn precursors, respectively. The impact of temperature (in the 300-350 °C range), Ge2H6 and SnCl4 mass-flows on the GeSn growth kinetics at 100 Torr has been thoroughly explored. Be it at 300 °C or 325 °C, a linear GeSn growth rate increase together with a sub-linear Sn concentration increase occurred as the SnCl4 mass-flow increased, irrespective of the Ge2H6 mass flow (fixed or varying). The Sn atoms seemed to catalyze H desorption from the surface, resulting in higher GeSn growth rates for high SnCl4 mass-flows (in the 4-21 nm min-1 range). The evolution of the Sn content x with the F (SnCl4) 2 ·/F (Ge2H6) mass-flow ratio was fitted by x2/(1 - x) = n ·F (SnCl4) 2 ·/F (Ge2H6), with n = 0.25 (325 °C) and 0.60 (300 °C). We have otherwise studied the impact of temperature, in the 300-350 °C range, on the GeSn growth kinetics. The GeSn growth rate exponentially increased with the temperature, from 15 up to 32 nm min-1. The associated activation energy was low, i.e. Ea = 10 kcal mol-1. Meanwhile, the Sn content decreased linearly as the growth temperature increased, from 15% at 300 °C down to 6% at 350 °C.

  18. Carbothermic Reduction Kinetics of Phosphorous Vaporization from Tri-calcium Phosphate (TCP) Under Microwave Rapid Heating With/Without the Presence of Fe3O4

    Science.gov (United States)

    Yoshikawa, Noboru; Sunako, Manami; Kawahira, Keita; Suzuki, Koki; Miyamoto, Kazunori; Taniguchi, Shoji

    2018-06-01

    The kinetics of vapor phase dephosphorization from tri-calcium phosphate (TCP) by carbothermic reduction was studied with and without the presence of Fe3O4. Microwave heating was utilized to obtain large variations in the heating rate (HR). In the reduction of TCP alone, the phosphorous removal fraction (RF; equal to ΔP2O5/P2O 5 0 , where ΔP2O5 is the weight change and P2O 5 0 is the P2O5 weight before heating) decreased as the HR increased. In other words, a shorter residence time at a high temperature resulted in a smaller reduction fraction of TCP. An apparently third-order reaction was postulated to account for the kinetics using a fitting simulation based on the additive law of the reaction progress. On the other hand, the phosphorous removal (dephosphorization) rate (RR; equal to ΔP2O3/ t MW, where tMW is the microwave heating time period) increased as the HR increased above 1200 °C. The reduction ratio of Fe3O4 above 1100 °C is higher than 97 pct regardless of the heating rate. The reduction of TCP in the presence of Fe3O4 showed that RF increased slightly with increasing HR despite a shorter residence time at a high temperature. The RR also increased with the HR even though RF decreased to half of the values observed in the cases without Fe3O4 for temperatures above 1200 °C. The practicality and optimal operation conditions of phosphorus vapor removal were discussed.

  19. Carbothermic Reduction Kinetics of Phosphorous Vaporization from Tri-calcium Phosphate (TCP) Under Microwave Rapid Heating With/Without the Presence of Fe3O4

    Science.gov (United States)

    Yoshikawa, Noboru; Sunako, Manami; Kawahira, Keita; Suzuki, Koki; Miyamoto, Kazunori; Taniguchi, Shoji

    2018-03-01

    The kinetics of vapor phase dephosphorization from tri-calcium phosphate (TCP) by carbothermic reduction was studied with and without the presence of Fe3O4. Microwave heating was utilized to obtain large variations in the heating rate (HR). In the reduction of TCP alone, the phosphorous removal fraction (RF; equal to ΔP2O5/P2O5 0 , where ΔP2O5 is the weight change and P2O5 0is the P2O5 weight before heating) decreased as the HR increased. In other words, a shorter residence time at a high temperature resulted in a smaller reduction fraction of TCP. An apparently third-order reaction was postulated to account for the kinetics using a fitting simulation based on the additive law of the reaction progress. On the other hand, the phosphorous removal (dephosphorization) rate (RR; equal to ΔP2O3/t MW, where tMW is the microwave heating time period) increased as the HR increased above 1200 °C. The reduction ratio of Fe3O4 above 1100 °C is higher than 97 pct regardless of the heating rate. The reduction of TCP in the presence of Fe3O4 showed that RF increased slightly with increasing HR despite a shorter residence time at a high temperature. The RR also increased with the HR even though RF decreased to half of the values observed in the cases without Fe3O4 for temperatures above 1200 °C. The practicality and optimal operation conditions of phosphorus vapor removal were discussed.

  20. Improvements of a COMS Land Surface Temperature Retrieval Algorithm Based on the Temperature Lapse Rate and Water Vapor/Aerosol Effect

    Directory of Open Access Journals (Sweden)

    A-Ra Cho

    2015-02-01

    Full Text Available The National Meteorological Satellite Center in Korea retrieves land surface temperature (LST by applying the split-window LST algorithm (CSW_v1.0 to Communication, Ocean, and Meteorological Satellite (COMS data. Considerable errors were detected under conditions of high water vapor content or temperature lapse rates during validation with Moderate Resolution Imaging Spectroradiometer (MODIS LST because of the too simplified LST algorithm. In this study, six types of LST retrieval equations (CSW_v2.0 were developed to upgrade the CSW_v1.0. These methods were developed by classifying “dry,” “normal,” and “wet” cases for day and night and considering the relative sizes of brightness temperature difference (BTD values. Similar to CSW_v1.0, the LST retrieved by CSW_v2.0 had a correlation coefficient of 0.99 with the prescribed LST and a slightly larger bias of −0.03 K from 0.00K; the root mean square error (RMSE improved from 1.41 K to 1.39 K. In general, CSW_v2.0 improved the retrieval accuracy compared to CSW_v1.0, especially when the lapse rate was high (mid-day and dawn and the water vapor content was high. The spatial distributions of LST retrieved by CSW_v2.0 were found to be similar to the MODIS LST independently of the season, day/night, and geographic locations. The validation using one year’s MODIS LST data showed that CSW_v2.0 improved the retrieval accuracy of LST in terms of correlations (from 0.988 to 0.989, bias (from −1.009 K to 0.292 K, and RMSEs (from 2.613 K to 2.237 K.

  1. Styrene process condensate treatment with a combination process of UF and NF for reuse.

    Science.gov (United States)

    Wang, Aijun; Liu, Guangmin; Huang, Jin; Wang, Lijuan; Li, Guangbin; Su, Xudong; Qi, Hong

    2013-01-15

    Aiming at reusing the SPC to save water resource and heat energy, a combination treatment process of UF/NF was applied to remove inorganic irons, suspended particles and little amount of organic contaminants in this article. To achieve the indexes of CODM≤5.00 mg L(-1), oil≤2.00 mg L(-1), conductivity≤10.00 μs cm(-1), pH of 6.0-8.0, the NF membrane process was adopted. It was necessary to employ a pretreatment process to reduce NF membrane fouling. Hence UF membrane as an efficient pretreatment unit was proposed to remove the inorganic particles, such as iron oxide catalyst, to meet the influent demands of NF. The effluent of UF, which was less than 0.02 mg L(-1) of total iron, went into a security filter and then was pumped into the NF process unit. High removal efficiencies of CODM, oil and conductivity were achieved by using NF process. The ABS grafting copolymerization experiment showed that the effluent of the combination process met the criteria of ABS production process, meanwhile the process could alleviate the environment pollution. It was shown that this combination process concept was feasible and successful in treating the SPC. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells

    International Nuclear Information System (INIS)

    Huber, B.; Baluktsian, T.; Schlagmueller, M.; Koelle, A.; Kuebler, H.; Loew, R.; Pfau, T.

    2011-01-01

    We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of ∼4 ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.

  3. Vortex-Induced Vapor Explosion during Drop Impact on a Superheated Pool

    KAUST Repository

    Alchalabi, M.A.

    2017-04-18

    Ultra high-speed imaging is used to investigate the vapor explosion when a drop impacts onto a high-temperature pool. The two liquids are immiscible, a low boiling-temperature perfluorohexane drop, at room temperature, which impacts a high boiling-temperature soybean-oil pool, which is heated well above the boiling temperature of the drop. We observe different regimes: weak and strong nucleate boiling, film boiling or Leidenfrost regime and entrainment followed by vapor explosion. The vapor explosions were seen to depend on the formation of a rotational flow at the edge of the impact crater, near the pool surface, which resembles a vortex ring. This rotational motion entrains a thin sheet of the drop liquid, to become surrounded by the oil. In that region, the vapor explosion starts at a point after which it propagates azimuthally along the entire periphery at high speed.

  4. Vortex-Induced Vapor Explosion during Drop Impact on a Superheated Pool

    KAUST Repository

    Alchalabi, M.A.; Kouraytem, Nadia; Li, Erqiang; Thoroddsen, Sigurdur T

    2017-01-01

    Ultra high-speed imaging is used to investigate the vapor explosion when a drop impacts onto a high-temperature pool. The two liquids are immiscible, a low boiling-temperature perfluorohexane drop, at room temperature, which impacts a high boiling-temperature soybean-oil pool, which is heated well above the boiling temperature of the drop. We observe different regimes: weak and strong nucleate boiling, film boiling or Leidenfrost regime and entrainment followed by vapor explosion. The vapor explosions were seen to depend on the formation of a rotational flow at the edge of the impact crater, near the pool surface, which resembles a vortex ring. This rotational motion entrains a thin sheet of the drop liquid, to become surrounded by the oil. In that region, the vapor explosion starts at a point after which it propagates azimuthally along the entire periphery at high speed.

  5. 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.

  6. Temperature Dependences of Mechanisms Responsible for the Water-Vapor Continuum Absorption

    Science.gov (United States)

    Ma, Qiancheng

    2014-01-01

    The water-vapor continuum absorption plays an important role in the radiative balance in the Earth's atmosphere. It has been experimentally shown that for ambient atmospheric conditions, the continuum absorption scales quadratically with the H2O number density and has a strong, negative temperature dependence (T dependence). Over the years, there have been three different theoretical mechanisms postulated: far-wings of allowed transition lines, water dimers, and collision-induced absorption. The first mechanism proposed was the accumulation of absorptions from the far-wings of the strong allowed transition lines. Later, absorption by water dimers was proposed, and this mechanism provides a qualitative explanation for the continuum characters mentioned above. Despite the improvements in experimental data, at present there is no consensus on which mechanism is primarily responsible for the continuum absorption.

  7. Uniform deposition of uranium hexafluoride (UF6): Standardized mass deposits and controlled isotopic ratios using a thermal fluorination method.

    Science.gov (United States)

    McNamara, Bruce K; O'Hara, Matthew J; Casella, Andrew M; Carter, Jennifer C; Addleman, R Shane; MacFarlan, Paul J

    2016-07-01

    We report a convenient method for the generation of volatile uranium hexafluoride (UF6) from solid uranium oxides and other U compounds, followed by uniform deposition of low levels of UF6 onto sampling coupons. Under laminar flow conditions, UF6 is shown to interact with surfaces within a fixed reactor geometry to a highly predictable degree. We demonstrate the preparation of U deposits that range between approximately 0.01 and 500ngcm(-2). The data suggest the method can be extended to creating depositions at the sub-picogramcm(-2) level. The isotopic composition of the deposits can be customized by selection of the U source materials and we demonstrate a layering technique whereby two U solids, each with a different isotopic composition, are employed to form successive layers of UF6 on a surface. The result is an ultra-thin deposit that bears an isotopic signature that is a composite of the two U sources. The reported deposition method has direct application to the development of unique analytical standards for nuclear safeguards and forensics. Further, the method allows access to very low atomic or molecular coverages of surfaces. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Vapor pressure and vapor fractionation of silicate melts of tektite composition

    Science.gov (United States)

    Walter, Louis S.; Carron, M.K.

    1964-01-01

    The total vapor pressure of Philippine tektite melts of approximately 70 per cent silica has been determined at temperatures ranging from 1500 to 2100??C. This pressure is 190 ?? 40 mm Hg at 1500??C, 450 ?? 50 mm at 1800??C and 850 ?? 70 mm at 2100?? C. Determinations were made by visually observing the temperature at which bubbles began to form at a constant low ambient pressure. By varying the ambient pressure, a boiling point curve was constructed. This curve differs from the equilibrium vapor pressure curve due to surface tension effects. This difference was evaluated by determining the equilibrium bubble size in the melt and calculating the pressure due to surface tension, assuming the latter to be 380 dyn/cm. The relative volatility from tektite melts of the oxides of Na, K, Fe, Al and Si has been determined as a function of temperature, total pressure arid roughly, of oxygen fugacity. The volatility of SiO2 is decreased and that of Na2O and K2O is increased in an oxygen-poor environment. Preliminary results indicate that volatilization at 2100??C under atmospheric pressure caused little or no change in the percentage Na2O and K2O. The ratio Fe3 Fe2 of the tektite is increased in ambient air at a pressure of 9 ?? 10-4 mm Hg (= 106.5 atm O2, partial pressure) at 2000??C. This suggests that tektites were formed either at lower oxygen pressures or that they are a product of incomplete oxidation of parent material with a still lower ferricferrous ratio. ?? 1964.

  9. Potential detection systems for monitoring UF6 releases

    International Nuclear Information System (INIS)

    Beck, D.E.; Bostick, W.D.; Armstrong, D.P.; McNeely, J.R.; Stockdale, J.A.D.

    1994-09-01

    In the near future, the Nuclear Regulatory Commission (NRC) will begin to regulate the gaseous diffusion plants. Them is a concern that the smoke detectors currently used for uranium hexafluoride (UF 6 ) release detection will not meet NRC safety system requirements such as high reliability and rapid response. The NRC's position is that licensees should utilize state-of-the-art equipment such as hydrogen fluoride (HF) detectors that would provide more dependable detection of a UF 6 release. A survey of the literature and current vendor information was undertaken to define the state-of-the-art and commercial availability of HF (or other appropriate) detection systems. For the purpose of this report, classification of the available HF detection systems is made on the basis of detection principle (e.g., calorimetric, electrochemical, separational, or optical). Emphasis is also placed on whether the device is primarily sensitive to response from a point source (e.g., outleakage in the immediate vicinity of a specific set of components), or whether the device is potentially applicable to remote sensing over a larger area. Traditional HF point source monitoring typically uses gas sampling tubes or coated paper tapes with color developing indicator, portable and small area HF monitors are often based upon electrochemical or extractive/separational systems; and remote sensing by optical systems holds promise for indoor and outdoor large area monitoring (including plant boundary/ambient air monitoring)

  10. Depleted UF6 Management Information Network - A resource for the public,

    Science.gov (United States)

    Depleted UF6 Management Information Network Web Site is an online repository of information about the U.S ) and DUF6, research and development efforts for beneficial uses of DU, DOE's program for management of line DUF6 Guide DUF6 Guide line Introductory information about depleted uranium: how it is created

  11. High frequency titration in non-aqueous solvents. Application to HF and UF6

    International Nuclear Information System (INIS)

    Neveu, Claude

    1965-01-01

    In this research thesis, the author first presents the main theoretical notions regarding high frequency titration, notably by studying characteristic curves, i.e. the titration meter indication with respect to conductibility. He reports the use of this method for the study of various reactions in non-aqueous medium: reaction of AlCl 3 with pyridine in acetonitrile, of AlCl 3 with HCl in tetrachloroethane and in nitromethane. He also reports the attempt of application of this method to the titration of HF in presence of UF 6 in CCl 4 as solvent, or by using F acceptors like BF 3 , PF 5 or ClF 3 as reactants [fr

  12. Vapor pressure and thermodynamics of beryllium carbide

    International Nuclear Information System (INIS)

    Rinehart, G.H.; Behrens, R.G.

    1980-01-01

    The vapor pressure of beryllium carbide has been measured over the temperature range 1388 to 1763 K using Knudsen-effusion mass spectrometry. Vaporization occurs incongruently according to the reaction Be 2 C(s) = 2Be(g) + C(s). The equilibrium vapor pressure above the mixture of Be 2 C and C over the experimental temperature range is (R/J K -1 mol -1 )ln(p/Pa) = -(3.610 +- 0.009) x 10 5 (K/T) + (221.43 +- 1.06). The third-law enthalpy change for the above reaction obtained from the present vapor pressures is ΔH 0 (298.15 K) = (740.5 +- 0.1) kJ mol -1 . The corresponding second-law result is ΔH 0 (298.15 K) = (732.0 +- 1.8) kJ mol -1 . The enthalpy of formation for Be 2 C(s) calculated from the present third-law vaporization enthalpy and the enthalpy of formation of Be(g) is ΔH 0 sub(f)(298.15 K) = -(92.5 +- 15.7) kJ mol -1 . (author)

  13. Probing the electronic structures of low oxidation-state uranium fluoride molecules UFx- (x = 2-4)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Li [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA; Hu, Han-Shi [Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China; William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Jian, Tian [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA; Lopez, Gary V. [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA; Su, Jing [Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China; Li, Jun [Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China; William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Wang, Lai-Sheng [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA

    2013-12-28

    We report the experimental observation of gaseous UFx- (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UFx (x = 2-4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f37s2)F2-, as a result of strong electron correlation effects of the two 7s electrons. The U-F symmetric stretching vibrational modes are resolved for the ground states of all UFx (x = 2-4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UFx- and UFx (x = 1-6) series are considered theoretically to examine the trends of U-F bonding and the electron affinities as a function of fluorine coordination. The increased U-F bond lengths and decreased bond orders from UF2- to UF4- indicate that the U-F bonding becomes weaker as the oxidation state of U increases from I to III.

  14. The vaporization enthalpies and vapor pressures of fatty acid methyl esters C18, C21 to C23, and C25 to C29 by correlation - gas chromatography

    International Nuclear Information System (INIS)

    Chickos, James S.; Zhao Hui; Nichols, Gary

    2004-01-01

    Vapor pressures and vaporization enthalpies for methyl heptadecanoate and methyl heneicosanoate to methyl octacosanoate exclusive of methyl tricosanoate are evaluated as a function of temperature over the temperature range T = 298.15-450 K by correlation gas chromatography. The results are generated by an extrapolative process using literature values for methyl tetradecanoate to methyl eicosanoate as standards. Relationships for calculating vapor pressures of the title compounds from T = 298.15 to 450 K are provided. Experimental fusion enthalpies are also reported for the methyl esters from methyl hexadecanoate to methyl octacosanoate excluding methyl tridecanoate. Vaporization enthalpies and fusion enthalpies adjusted for temperature to T = 298.15 K are combined to provide sublimation enthalpies. The results are compared to available literature values. A rationale for the linear relationship observed between enthalpies of vaporization and enthalpies of transfer from solution to the vapor is also provided

  15. The COMURHEX 2 project. Investing in UF6 long-term security of supply

    International Nuclear Information System (INIS)

    Bouzon, Pierre; Lacombe, Philippe; Durante, Pierre; Teyssier, Patrick

    2008-01-01

    The front-end nuclear fuel supply chain for LWRs encompasses four major industrial stages that are mining and concentration, conversion, enrichment, and eventually fuel fabrication. The different stages involve uranium in different chemical and physical forms. Enrichment of the 235-U fissile isotope requires gaseous UF6. As the standard output of mine is U3O8, referred to as ''yellow cake'', a purely chemical stage is therefore needed to fluorinate U3O8 and turn it into UFe: this is the conversion stage. U3O8 inventories management is thus performed at the conversion sites.Purification of the mining concentrates is also needed prior to actual conversion into UFe. This step is important because the front-end supply chain facilities have strict specifications concerning impurities. The conversion stage may involve intermediary products, namely UO3 and/or UF4, depending on the industrial scheme implemented. With the Comurhex 2 project, AREVA is not only shaping the future of conversion market and contributing to the security of supply of its customers, but it is also developing innovative techniques and reorganizing the conversion process steps. Providing such guaranteed and valuable conversion supply with a brand new plant is our strong commitment to a sustainable nuclear fuel cycle. And AREVA is the first that has launched such a project, looking further ahead. The three main axes of sustainable development, economical, social, and environmental, are truly taken into account in the development of the new project.

  16. Chemical vapor deposition of NiSi using Ni(PF3)4 and Si3H8

    International Nuclear Information System (INIS)

    Ishikawa, M.; Muramoto, I.; Machida, H.; Imai, S.; Ogura, A.; Ohshita, Y.

    2007-01-01

    NiSi x films were deposited using chemical vapor deposition (CVD) with a Ni(PF 3 ) 4 and Si 3 H 8 /H 2 gas system. The step coverage quality of deposited NiSi x was investigated using a horizontal type of hot-wall low pressure CVD reactor, which maintained a constant temperature throughout the deposition area. The step coverage quality improved as a function of the position of the gas flow direction, where PF 3 gas from decomposition of Ni(PF 3 ) 4 increased. By injecting PF 3 gas into the Ni(PF 3 ) 4 and Si 3 H 8 /H 2 gas system, the step coverage quality markedly improved. This improvement in step coverage quality naturally occurred when PF 3 gas was present, indicating a strong relationship. The Si/Ni deposit ratio at 250 deg. C is larger than at 180 deg. C. It caused a decreasing relative deposition rate of Ni to Si. PF 3 molecules appear to be adsorbed on the surface of the deposited film and interfere with faster deposition of active Ni deposition species

  17. RESPEITO À CIDADANIA: PROVENDO ACESSIBILIDADE WEB NA UNIVERSIDADE FEDERAL DE SERGIPE (UFS

    Directory of Open Access Journals (Sweden)

    Quelita Araújo Diniz da Silva

    2012-03-01

    Full Text Available O acesso à informação facilitado pelas Tecnologias de Informação e Comunicação (TIC é um dos principais elementos da sociedade do conhecimento, sendo visto como possibilidade de inclusão social. Entretanto, alguns indivíduos possuem necessidades, permanentes ou temporárias, que os limitam no acesso às informações disponibilizadas, mantendo-os à periferia da sociedade. Este trabalho tem como objetivo discutir a acessibilidade na Web, discutindo os principais padrões, as diretrizes e técnicas para o projeto de webapps acessíveis. Como também, expor o conceito de tecnologias assistivas e como elas adequam às funcionalidades computacionais ao internauta com necessidades especiais auxiliando-o na navegação. Por fim, descrever um estudo de caso realizado no site da POSGRAP – UFS objetivando viabilizar à comunidade Sergipana à inclusão provendo acessibilidade aos produtos e serviços da UFS.

  18. Thermogravimetric measurements of liquid vapor pressure

    International Nuclear Information System (INIS)

    Rong Yunhong; Gregson, Christopher M.; Parker, Alan

    2012-01-01

    Highlights: ► Rapid determination of vapor pressure by TGA. ► Demonstration of limitations of currently available approaches in literature. ► New model for vapor pressure assessment of small size samples in TGA. ► New model accounts for vapor diffusion and sample geometry and measures vapor pressure normally within 10%. - Abstract: A method was developed using thermo-gravimetric analysis (TGA) to determine the vapor pressure of volatile liquids. This is achieved by measuring the rate of evaporation (mass loss) of a pure liquid contained within a cylindrical pan. The influence of factors like sample geometry and vapor diffusion on evaporation rate are discussed. The measurement can be performed across a wide range of temperature yielding reasonable results up to 10 kPa. This approach may be useful as a rapid and automatable method for measuring the volatility of flavor and fragrance raw materials.

  19. Determination of the enthalpy of vaporization and prediction of surface tension for ionic liquid 1-alkyl-3-methylimidazolium propionate [C(n)mim][Pro](n = 4, 5, 6).

    Science.gov (United States)

    Tong, Jing; Yang, Hong-Xu; Liu, Ru-Jing; Li, Chi; Xia, Li-Xin; Yang, Jia-Zhen

    2014-11-13

    With the use of isothermogravimetrical analysis, the enthalpies of vaporization, Δ(g)lH(o)m(T(av)), at the average temperature, T(av) = 445.65 K, for the ionic liquids (ILs) 1-alkyl-3-methylimidazolium propionate [C(n)mim][Pro](n = 4, 5, 6) were determined. Using Verevkin's method, the difference of heat capacities between the vapor phase and the liquid phase, Δ(g)lC(p)(o)m, for [C(n)mim][Pro](n = 2, 3, 4, 5, 6), were calculated based on the statistical thermodynamics. Therefore, with the use of Δ(g)lC(p)(o)m, the values of Δ(g)lH(o)m(T(av)) were transformed into Δ(g)lH(o)m(298), 126.8, 130.3, and 136.5 for [C(n)mim][Pro](n = 4, 5, 6), respectively. In terms of the new scale of polarity for ILs, the order of the polarity of [C(n)mim][Pro](n = 2, 3, 4, 5, 6) was predicted, that is, the polarity decreases with increasing methylene. A new model of the relationship between the surface tension and the enthalpy of vaporization for aprotic ILs was put forward and used to predict the surface tension for [C(n)mim][Pro](n = 2, 3, 4, 5, 6) and others. The predicted surface tension for the ILs is in good agreement with the experimental one.

  20. Mass Spectrometric Identification of Si-O-H(g) Species from the Reaction of Silica with Water Vapor at Atmospheric Pressure

    Science.gov (United States)

    Opila, Elizabeth J.; Fox, Dennis S.; Jacobson, Nathan S.

    1997-01-01

    A high-pressure sampling mass spectrometer was used to detect the volatile species formed from SiO2 at temperatures between 1200C and 1400C in a flowing water vapor/oxygen gas mixture at 1 bar total pressure. The primary vapor species identified was Si(OH)4. The fragment ion Si(OH)3+,' was observed in quantities 3 to 5 times larger than the parent ion Si(OH)4+. The Si(OH)3+ intensity was found to have a small temperature dependence and to increase with the water vapor partial pressure as expected. In addition, SiO(OH)+ believed to be a fragment of SiO(OH)2, was observed. These mass spectral results were compared to the behavior of silicon halides.

  1. The thermodynamic characteristics of vaporization in the NaI-PrI3 system

    Science.gov (United States)

    Motalov, V. B.; Kudin, L. S.; Markus, T.

    2009-05-01

    The vaporization of the NaI-PrI3 quasi-binary system was studied by high-temperature mass spectrometry over the whole concentration range. At 623-994 K, saturated vapor contained not only (NaI) n and (PrI3) n molecules ( n = 1, 2) and Na+(NaI) n ( n = 0-4) and I-(PrI3) n ( n = 1-2) ions but also mixed molecular and ionic associates recorded for the first time (NaPrI4, Na2PrI5, NaPrI{3/+}, Na2PrI{4/+}, Na3PrI{5/+}, Na4PrI{6/+}, NaPrI{5/-}, and NaPr2I{8/-}). The partial vapor pressures of molecules were calculated, and the equilibrium constants of the dissociation of neutral and charged associates were measured. The enthalpies of molecular and ion-molecular reactions were determined, and the enthalpies of formation of gaseous molecules and ions were obtained.

  2. Constrained Vapor Bubble Experiment

    Science.gov (United States)

    Gokhale, Shripad; Plawsky, Joel; Wayner, Peter C., Jr.; Zheng, Ling; Wang, Ying-Xi

    2002-11-01

    Microgravity experiments on the Constrained Vapor Bubble Heat Exchanger, CVB, are being developed for the International Space Station. In particular, we present results of a precursory experimental and theoretical study of the vertical Constrained Vapor Bubble in the Earth's environment. A novel non-isothermal experimental setup was designed and built to study the transport processes in an ethanol/quartz vertical CVB system. Temperature profiles were measured using an in situ PC (personal computer)-based LabView data acquisition system via thermocouples. Film thickness profiles were measured using interferometry. A theoretical model was developed to predict the curvature profile of the stable film in the evaporator. The concept of the total amount of evaporation, which can be obtained directly by integrating the experimental temperature profile, was introduced. Experimentally measured curvature profiles are in good agreement with modeling results. For microgravity conditions, an analytical expression, which reveals an inherent relation between temperature and curvature profiles, was derived.

  3. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Djenadic, Ruzica; Winterer, Markus, E-mail: markus.winterer@uni-due.de [Universität Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and CENIDE (Germany)

    2017-02-15

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  4. Near room temperature chemical vapor deposition of graphene with diluted methane and molten gallium catalyst.

    Science.gov (United States)

    Fujita, Jun-Ichi; Hiyama, Takaki; Hirukawa, Ayaka; Kondo, Takahiro; Nakamura, Junji; Ito, Shin-Ichi; Araki, Ryosuke; Ito, Yoshikazu; Takeguchi, Masaki; Pai, Woei Wu

    2017-09-28

    Direct growth of graphene integrated into electronic devices is highly desirable but difficult due to the nominal ~1000 °C chemical vapor deposition (CVD) temperature, which can seriously deteriorate the substrates. Here we report a great reduction of graphene CVD temperature, down to 50 °C on sapphire and 100 °C on polycarbonate, by using dilute methane as the source and molten gallium (Ga) as catalysts. The very low temperature graphene synthesis is made possible by carbon attachment to the island edges of pre-existing graphene nuclei islands, and causes no damages to the substrates. A key benefit of using molten Ga catalyst is the enhanced methane absorption in Ga at lower temperatures; this leads to a surprisingly low apparent reaction barrier of ~0.16 eV below 300 °C. The faster growth kinetics due to a low reaction barrier and a demonstrated low-temperature graphene nuclei transfer protocol can facilitate practical direct graphene synthesis on many kinds of substrates down to 50-100 °C. Our results represent a significant progress in reducing graphene synthesis temperature and understanding its mechanism.

  5. The impact of vaporized nanoemulsions on ultrasound-mediated ablation.

    Science.gov (United States)

    Zhang, Peng; Kopechek, Jonathan A; Porter, Tyrone M

    2013-01-01

    The clinical feasibility of using high-intensity focused ultrasound (HIFU) for ablation of solid tumors is limited by the high acoustic pressures and long treatment times required. The presence of microbubbles during sonication can increase the absorption of acoustic energy and accelerate heating. However, formation of microbubbles within the tumor tissue remains a challenge. Phase-shift nanoemulsions (PSNE) have been developed as a means for producing microbubbles within tumors. PSNE are emulsions of submicron-sized, lipid-coated, and liquid perfluorocarbon droplets that can be vaporized into microbubbles using short (5 MPa) acoustic pulses. In this study, the impact of vaporized phase-shift nanoemulsions on the time and acoustic power required for HIFU-mediated thermal lesion formation was investigated in vitro. PSNE containing dodecafluoropentane were produced with narrow size distributions and mean diameters below 200 nm using a combination of sonication and extrusion. PSNE was dispersed in albumin-containing polyacrylamide gel phantoms for experimental tests. Albumin denatures and becomes opaque at temperatures above 58°C, enabling visual detection of lesions formed from denatured albumin. PSNE were vaporized using a 30-cycle, 3.2-MHz, at an acoustic power of 6.4 W (free-field intensity of 4,586 W/cm(2)) pulse from a single-element, focused high-power transducer. The vaporization pulse was immediately followed by a 15-s continuous wave, 3.2-MHz signal to induce ultrasound-mediated heating. Control experiments were conducted using an identical procedure without the vaporization pulse. Lesion formation was detected by acquiring video frames during sonication and post-processing the images for analysis. Broadband emissions from inertial cavitation (IC) were passively detected with a focused, 2-MHz transducer. Temperature measurements were acquired using a needle thermocouple. Bubbles formed at the HIFU focus via PSNE vaporization enhanced HIFU-mediated heating

  6. Impact of Acid Cleaning on the Performance of PVDF UF Membranes in Seawater Reverse Osmosis Pretreatment

    KAUST Repository

    Alsogair, Safiya

    2016-05-05

    Low-pressure membrane systems such as Microfiltration (MF) and Ultrafiltration (UF) have been presented as viable option to pre-treatment systems in potable water applications. UF membranes are sporadically backwashed with ultra-filtered water to remove deposited matter from the membrane and restore it. Several factors that may cause permeability and selectivity decrease are involved and numerous procedures are applicable to achieve this objective. Membrane cleaning is the most important step required to maintain the characteristics of the membrane. This research was made with the purpose of investigating the effects of acid cleaning during chemically enhanced backwashing (CEB) on the performance of ultrafiltration (UF) membranes in seawater reverse osmosis (SWRO) pretreatment. To accomplish this, the questions made were: Does the acid addition (before or after the alkali CEB) influence the overall CEB cleaning effectiveness on Dow UF membrane? Does the CEB order of alkali (NaOCl) and acid (H2SO4) affect the overall CEB cleaning effectiveness? If yes, which order is better/worse? What is the optimal acid CEB frequency that will ensure the most reliable performance of the UF?. To answer this queries, a series of sequences were carried out with different types of chemical treatments: Only NaOCl, daily NaOCl plus weekly acid, daily NaOCl plus daily acid, and weekly acid plus daily NaOCl. To investigate the consequence of acid by studying the effect of operational data like the trans-pressure membrane, resistance or permeability and support that by the analytical experiments (organic, inorganic and microbial characterization). Microorganisms were removed almost completely at hydraulic cleaning and showed no difference with addition of acid. As a conclusion of the operational data the organic and inorganic chatacterization resulted in the elimination of the first sequence due to the acummulation of fouling over time, which produces that the cleaning increases downtime

  7. Vaporization of Samarium trichloride studied by thermogravimetry

    International Nuclear Information System (INIS)

    Esquivel, Marcelo R.; Pasquevich, Daniel M.

    2003-01-01

    In the present work, the vaporization reaction of SmCl 3 (l) obtained from the 'in situ' reaction of Sm 2 O 3 (s) and Cl 2 (g)-C(s) was studied by thermogravimetry under controlled atmosphere. The effects of both the temperature between 825 C degrees and 950 C degrees and the total flow gas on the vaporization rate of the following reaction: SmCl 3 (l) = SmCl 3 (g) were analyzed. The vaporization rate of the process was found to be independent of then total gas flow rate and highly dependent on the temperature. E ap calculation led to a value of 240 ± 10 kJ.mol -1 . A comparison between this value and that of the molar enthalpy of vaporization allow to the conclusion that the reaction occur in conditions near to equilibrium. The SmCl 3 identity was determined by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). (author)

  8. Temperature distribution in the reactive jet of water vapor and liquid sodium - contribution to wastage modelling

    International Nuclear Information System (INIS)

    Roger, F.; Park, K.Y.; Carreau, J.L.; Gbahoue, L.; Hobbes, P.

    1984-08-01

    The possibility of water vapor leaks across the wall of one or more of the heat exchanger tubes in the steam generator constitutes one of the important problems of safety of the Fast Breeder Reactors cooled by sodium. The jet thus formed can, in fact, destroy the neighbouring tubes. The hydrodynamic, chemical and thermal factors play an important role in this phenomenon and only the last-mentionned will be studied here. The use of the integral method of analysis, complemented by an experimental study, shows that the temperature profiles are Gaussian; if the maximum temperature is less than that of the boiling point of sodium, i.e. 1155 K, and for steam flow rates less than 0,5g/s, the temperature profiles can be represented by the error function, and an approximate equation gives the difference in temperature between the jet axis and the radical far-field

  9. Potential ability of zeolite to generate high-temperature vapor using waste heat

    Science.gov (United States)

    Fukai, Jun; Wijayanta, Agung Tri

    2018-02-01

    In various material product industries, a large amount of high temperature steam as heat sources are produced from fossil fuel, then thermal energy retained by condensed water at lower than 100°C are wasted. Thermal energies retained by exhaust gases at lower than 200°C are also wasted. Effective utilization of waste heat is believed to be one of important issues to solve global problems of energy and environment. Zeolite/water adsorption systems are introduced to recover such low-temperature waste heats in this study. Firstly, an adsorption steam recovery system was developed to generate high temperature steam from unused hot waste heat. The system used a new principle that adsorption heat of zeolite/water contact was efficiently extracted. A bench-scaled system was constructed, demonstrating contentious generation of saturated steam nearly 150°C from hot water at 80°C. Energy conservation is expected by returning the generated steam to steam lines in the product processes. Secondly, it was demonstrated that superheated steam/vapor at higher than 200°C could be generated from those at nearly 120°C using a laboratory-scaled setup. The maximum temperature and the time variation of output temperature were successfully estimated using macroscopic heat balances. Lastly, the maximum temperatures were estimated whose saturate air at the relative humidity 20-80% were heated by the present system. Theoretically, air at higher than 200°C was generated from saturate air at higher than 70°C. Consequently, zeolite/water adsorption systems have potential ability to regenerate thermal energy of waste water and exhaust gases.

  10. Emergency preparedness and response in case of a fire accident with (UF6) packages tracking Suez Canal

    International Nuclear Information System (INIS)

    Salama, M.

    2004-01-01

    Egypt has a unique problem - the Suez Canal. Radioactive cargo passing regularly through the canal carrying new and spent reactor fuel. Moreover there are also about 1000 metric tons of uranium hexaflouride (UF6) passing through the canal every year. In spite of all precautions taken in the transportation, accidents with packages containing (UF 6 ) and shipped through the Suez Canal, accidents may arise even though the probability is minimal. These accidents, may be accompanied by injuries or death of persons and damage to property. Due to the radiation and criticality hazards of (UF 6 ) and its high risk of chemical toxicity. The probability of a fire accident with a cargo carrying (UF 6 ) during its crossing the Suez Canal can cause serious chemical toxic and radiological hazards, particularly if the accident occurred close or near to one of the three densely populated cities (Port-Said, Ismailia, and Suez), which are located along the Suez Canal, west bank. The government of Egypt has elaborated a national radiological emergency plan inorder to face probable radiological accidents, which may be arised inside the country. Arrangements have been also elaborated for the medical care of any persons who, might be injured or contaminated, or who, have been exposed to severe radiation doses. The motivation of the present paper was undertaken to visualize a fire accident scenario occurring in industrial packages containing UF6 on board of a Cargo crossing the Suez Canal near Port-Said City. The accident scenario and emergency response actions taken during the different phases of the accident are going to be presented and discussed. The proposed emergency response actions taken to face the accident are going to be also presented. The work presented had revealed the importance of public awareness will be needed for populations located in densely populated areas along Suez Canal bank inorder to react timely and effectively to avoid the toxic and radiological hazards

  11. Incorporation of Titanium into H-ZSM-5 Zeolite via Chemical Vapor Deposition: Effect of Steam Treatment

    International Nuclear Information System (INIS)

    Xu, Cheng Hua; Jin, Tai Huan; Jhung, Sung Hwa; Hwang, Jin Soo; Chang, Jong San; Qiu, Fa Li; Park, Sang Eon

    2004-01-01

    Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl 4 , was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl 4 with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 .deg. C or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl 4 was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis

  12. Incorporation of Titanium into H-ZSM-5 Zeolite via Chemical Vapor Deposition: Effect of Steam Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Cheng Hua; Jin, Tai Huan; Jhung, Sung Hwa; Hwang, Jin Soo [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Chang, Jong San; Qiu, Fa Li [Chinese Academy of Sciences(CAS), Chengdu (China); Park, Sang Eon [Inha University, Incheon (Korea, Republic of)

    2004-05-15

    Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl{sub 4}, was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl{sub 4} with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 .deg. C or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl{sub 4} was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis.

  13. Physico-chemical characterization antituberculosis thioacetazone: Vapor pressure, solubility and lipophilicity

    International Nuclear Information System (INIS)

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

    2017-01-01

    Highlights: • Vapor pressures of antituberculosis thioacetazone were determined by transpiration method. • Solubilities of the TAZ in four modeling solvents were measured at different temperatures. • Temperature dependence of octanol/buffer pH 7.4 partition coefficients was obtained. • Thermodynamics parameters of solubility, sublimation, solvation and transfer were calculated. - Abstract: Vapor pressure of thioacetazone (TAZ) has been determined in the temperature range of 404.15–429.15 K by the transpiration method. The obtained data were used to calculate the standard molar enthalpy of sublimation that was found to be 164.1 kJ/mol at T = 298.15 K. The drug solubility was measured at seven temperatures from 288.15 to 318.15 K in modeling solvents: octanol, hexane and aqueous buffers pH 2.0 and 7.4 by the saturation shake-flask method by using spectrophotometric analysis. It has been found that TAZ has poor solubility in hexane and buffer solutions and limited solubility in octanol. The experimental data were well correlated by van’t Hoff and modified Apelblat equations. A temperature dependence of TAZ partition coefficient in the octanol/buffer pH 7.4 system has been derived. The partition coefficient value in this system (logP = 1.82) refers to the optimal interval for oral absorption drugs. The thermodynamic parameters of sublimation, solubility, solvation and transfer have been determined based on experimental data. The dominant effect of enthalpy and entropy contributions to the Gibbs energy of the investigated processes has been revealed.

  14. Vapor generation rate model for dispersed drop flow

    International Nuclear Information System (INIS)

    Unal, C.; Tuzla, K.; Cokmez-Tuzla, A.F.; Chen, J.C.

    1991-01-01

    A comparison of predictions of existing nonequilibrium post-CHF heat transfer models with the recently obtained rod bundle data has been performed. The models used the experimental conditions and wall temperatures to predict the heat flux and vapor temperatures at the location of interest. No existing model was able to reasonably predict the vapor superheat and the wall heat flux simultaneously. Most of the models, except Chen-Sundaram-Ozkaynak, failed to predict the wall heat flux, while all of the models could not predict the vapor superheat data or trends. A recently developed two-region heat transfer model, the Webb-Chen two-region model, did not give a reasonable prediction of the vapor generation rate in the far field of the CHF point. A new correlation was formulated to predict the vapor generation rate in convective dispersed droplet flow in terms of thermal-hydraulic parameters and thermodynamic properties. A comparison of predictions of the two-region heat transfer model, with the use of a presently developed correlation, with all the existing post-CHF data, including single-tube and rod bundle, showed significant improvements in predicting the vapor superheat and tube wall heat flux trends. (orig.)

  15. Experimental determination of CCl4 hydrate phase equlibria up to high pressures

    NARCIS (Netherlands)

    Shariati - Sarabi, A.; Lameris, G.H.; Peters, C.J.

    2015-01-01

    A number of hydrate phase boundaries of the binary system of tetrachloromethane (CCl4) + water were measured experimentally at several temperatures and from low pressures up to 89.25 MPa. These hydrate phase boundaries included hydrate–ice–vapor, hydrate–liquid CCl4vapor, hydrate–water–vapor,

  16. Exchange reaction between tritiated hydrogen and water vapor

    International Nuclear Information System (INIS)

    Yamada, Koichi; Takano, Kenichi; Watanabe, Tamaki.

    1979-01-01

    Exchange reaction of tritiated hydrogen to water vapor under the condition of tritium gas concentration between 1 μCi/l and 1 mCi/l was studied. Tritium gas with hydrogen gas of 5 Torr and water of 20 mg were enclosed in a Pyrex glass ampule with volume of about 100 ml. The mixed gas with water vapor was heated with electric furnace. The heating time was between 2 and 100 hr, and the temperature was 776, 725, 675, 621, and 570.5 0 K. After heating, tritiated water was trapped with liquid nitrogen, and counted with a liquid scintillation counter. The radioactive concentration of initial tritiated hydrogen was measured with a calibrated ionization chamber. The main results obtained are as follows; 1) the concentration of produced tritiated water is well proportioned to that of initial tritiated hydrogen, 2) the activation energy of exchange reaction from tritiated hydrogen to tritiated water is 26.2 kcal/mol and that of inverse reaction is 27.4 kcal/mol, 3) the reaction rate at room temperature which calculated with activation energy is 1.04 x 10 -13 day -1 , and then exchange reaction at room temperature is negligible. (author)

  17. Decrease in lower level density due to cooling of gas temperature by thermal dissociation of hydrogen in copper vapor laser

    International Nuclear Information System (INIS)

    Watanabe, Ikuo; Hayashi, Kazuo; Iseki, Yasushi; Suzuki, Setsuo; Noda, Etsuo; Morimiya, Osamu

    1995-01-01

    A gas temperature calculation is carried out in the copper vapor laser (CVL) with a beam diameter of 80 mm in the case of H 2 addition into the Ne buffer gas. The on-axis gas temperature decreases to 2800K with 1% concentration of H 2 , whereas the gas temperature is 3400K without H 2 . The on-axis lower level density decreases due to the cooling of the gas temperature. This decrease in the lower level density is thought to bring about a non annular beam profile in the case of H 2 addition. (author)

  18. Water vapor changes under global warming and the linkage to present-day interannual variabilities in CMIP5 models

    Science.gov (United States)

    Takahashi, Hanii; Su, Hui; Jiang, Jonathan H.

    2016-12-01

    The fractional water vapor changes under global warming across 14 Coupled Model Intercomparison Project Phase 5 simulations are analyzed. We show that the mean fractional water vapor changes under global warming in the tropical upper troposphere between 300 and 100 hPa range from 12.4 to 28.0 %/K across all models while the fractional water vapor changes are about 5-8 %/K in other regions and at lower altitudes. The "upper-tropospheric amplification" of the water vapor change is primarily driven by a larger temperature increase in the upper troposphere than in the lower troposphere per degree of surface warming. The relative contributions of atmospheric temperature and relative humidity changes to the water vapor change in each model vary between 71.5 to 131.8 % and 24.8 to -20.1 %, respectively. The inter-model differences in the water vapor change is primarily caused by differences in temperature change, except over the inter-tropical convergence zone within 10°S-10°N where the model differences due to the relative humidity change are significant. Furthermore, we find that there is generally a positive correlation between the rates of water vapor change for long-tem surface warming and those on the interannual time scales. However, the rates of water vapor change under long-term warming have a systematic offset from those on the inter-annual time scales and the dominant contributor to the differences also differs for the two time scales, suggesting caution needs to be taken when inferring long-term water vapor changes from the observed interannual variations.

  19. Fracture mechanics performance of UF6 containers

    International Nuclear Information System (INIS)

    Gonzalez, M.E.; Iorio, A.F.; Crespi, J.C.

    1993-01-01

    The main purpose of this work was to determine the fracture mechanics performance of UF 6 transport cylinders type ANSI N14.1.30B, which was made from ASTM A 516 Grade 70 steel. It was assumed an internal surface axial crack subjected to stresses due to service, proof and transport accident loads. The KUMAR-GERMAN-SHIH elastoplastic methodology gave adequate results for crack depth estimation. The results validate the leak-before-break criteria for service and proof conditions but not for accident ones. In the last case a non-destructive examination must be done in order to assure the absence of defects larger than one third of the cylinder wall thickness. (Author)

  20. Effect of evaporator temperature on vapor compression refrigeration system

    Directory of Open Access Journals (Sweden)

    Abdullah A.A.A. Al-Rashed

    2011-12-01

    Full Text Available This paper presents a comparable evaluation of R600a (isobutane, R290 (propane, R134a, R22, for R410A, and R32 an optimized finned-tube evaporator, and analyzes the evaporator effect on the system coefficient of performance (COP. Results concerning the response of a refrigeration system simulation software to an increase in the amount of oil flowing with the refrigerant are presented. It is shown that there is optima of the apparent overheat value, for which either the exchanged heat or the refrigeration coefficient of performance (COP is maximized: consequently, it is not possible to optimize both the refrigeration COP and the evaporator effect. The obtained evaporator optimization results were incorporated in a conventional analysis of the vapor compression system. For a theoretical cycle analysis without accounting for evaporator effects, the COP spread for the studied refrigerants was as high as 11.7%. For cycle simulations including evaporator effects, the COP of R290 was better than that of R22 by up to 3.5%, while the remaining refrigerants performed approximately within a 2% COP band of the R22 baseline for the two condensing temperatures considered.

  1. 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

  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. Temperature dependence of InN growth on (0001) sapphire substrates by atmospheric pressure hydride vapor phase epitaxy

    International Nuclear Information System (INIS)

    Kumagai, Yoshinao; Adachi, Hirokazu; Otake, Aya; Higashikawa, Yoshihiro; Togashi, Rie; Murakami, Hisashi; Koukitu, Akinori

    2010-01-01

    The temperature dependence of InN growth on (0001) sapphire substrates by atmospheric pressure hydride vapor phase epitaxy (HVPE) was investigated. N-polarity single-crystal InN layers were successfully grown at temperatures ranging from 400 to 500 C. The a and c lattice constants of InN layers grown at 450 C or below were slightly larger than those of InN layers grown above 450 C due to oxygen incorporation that also increased the carrier concentration. The optical absorption edge of the InN layer decreased from above 2.0 to 0.76 eV when the growth temperature was increased from 450 to 500 C. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Thermodynamics of the vaporization of uranium tetrabromide

    International Nuclear Information System (INIS)

    Singh, Z.; Prasad, R.; Venugopal, P.V.; Roy, K.N.; Sood, D.D.

    1981-01-01

    Vapour pressures of solid and liquid uranium tetrabromide have been measured in the temperature range of 696 to 805 K and 805 to 1003 K respectively by transpiration and evaporation-temperature techniques. The vapour pressures obtained by the two techniques are in good agreement and have been combined to give the reported vapour-pressure equations for solid and liquid uranium tetrabromide. The melting temperature, the normal boiling temperature, the standard enthalpy of vaporization ΔH 0 (vap, 298.15 K), and the standard entropy of vaporization ΔS 0 (vap, 298.15 K) are reported. The enthalpy of fusion ΔH 0 (fus, 802 K) is also reported. The thermodynamic quantities from the present study are compared with those in the literature and critically analysed. (author)

  5. Monitoring tropospheric water vapor changes using radiosonde data

    International Nuclear Information System (INIS)

    Elliott, W.P.; Smith, M.E.; Angell, J.K.

    1990-01-01

    Significant increases in the water vapor content of the troposphere are expected to accompany temperature increases due to rising concentrations of the greenhouse gases. Thus it is important to follow changes in water vapor over time. There are a number of difficulties in developing a homogeneous data set, however, because of changes in radiosonde instrumentation and reporting practices. The authors report here on preliminary attempts to establish indices of water vapor which can be monitored. The precipitable water between the surface and 500 mb is the first candidate. They describe their method for calculating this quantity from radiosonde data for a network very similar to the network Angell uses for detecting temperature trends. Preliminary results suggest that the noise level is low enough to detect trends in water vapor at the individual stations. While a slight increase in global water vapor is hinted at in the data, and the data suggest there may have been a net transfer of water from the Southern Hemisphere to the Northern Hemisphere, these conclusions are tentative. The authors also discuss the future course of this investigation

  6. Study of film boiling collapse behavior during vapor explosion

    International Nuclear Information System (INIS)

    Yagi, Masahiro; Yamano, Norihiro; Sugimoto, Jun; Abe, Yutaka; Adachi, Hiromichi; Kobayashi, Tomoyoshi.

    1996-06-01

    Possible large scale vapor explosions are safety concern in nuclear power plants during severe accident. In order to identify the occurrence of the vapor explosion and to estimate the magnitude of the induced pressure pulse, it is necessary to investigate the triggering condition for the vapor explosion. As a first step of this study, scooping analysis was conducted with a simulation code based on thermal detonation model. It was found that the pressure at the collapse of film boiling much affects the trigger condition of vapor explosion. Based on this analytical results, basic experiments were conducted to clarify the collapse conditions of film boiling on a high temperature solid ball surface. Film boiling condition was established by flooding water onto a high temperature stainless steel ball heated by a high frequency induction heater. After the film boiling was established, the pressure pulse generated by a shock tube was applied to collapse the steam film on the ball surface. As the experimental boundary conditions, materials and size of the balls, magnitude of pressure pulse and initial temperature of the carbon and stainless steel balls were varied. The transients of pressure and surface temperature were measured. It was found that the surface temperature on the balls sharply decreased when the pressure wave passed through the film on balls. Based on the surface temperature behavior, the film boiling collapse pattern was found to be categorized into several types. Especially, the pattern for stainless steel ball was categorized into three types; no collapse, collapse and reestablishment after collapse. It was thus clarified that the film boiling collapse behavior was identified by initial conditions and that the pressure required to collapse film boiling strongly depended on the initial surface temperature. The present results will provide a useful information for the analysis of vapor explosions based on the thermal detonation model. (J.P.N.)

  7. Quality assurance in the transport of UF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Ravenscroft, N.L. [Edlow International Company, Washington, DC (United States)

    1991-12-31

    Edlow International`s primary business is the international transportation of radioactive materials. Therefore, Edlow has the responsibility to ensure that shipments are performed in compliance with regulatory requirements. In this regard, Edlow maintains a Quality Assurance (QA) Program. A major part of this Program is the establishment and use of QA Procedures. This paper addresses QA procedural requirements and how they are applied to a routine international shipment of low enriched UF{sub 6}. Only the major requirements for scheduling shipments will be addressed.

  8. The Effect of High Temperature Annealing on the Grain Characteristics of a Thin Chemical Vapor Deposition Silicon Carbide Layer.

    Energy Technology Data Exchange (ETDEWEB)

    Isabella J van Rooyen; Philippus M van Rooyen; Mary Lou Dunzik-Gougar

    2013-08-01

    The unique combination of thermo-mechanical and physiochemical properties of silicon carbide (SiC) provides interest and opportunity for its use in nuclear applications. One of the applications of SiC is as a very thin layer in the TRi-ISOtropic (TRISO) coated fuel particles for high temperature gas reactors (HTGRs). This SiC layer, produced by chemical vapor deposition (CVD), is designed to withstand the pressures of fission and transmutation product gases in a high temperature, radiation environment. Various researchers have demonstrated that macroscopic properties can be affected by changes in the distribution of grain boundary plane orientations and misorientations [1 - 3]. Additionally, various researchers have attributed the release behavior of Ag through the SiC layer as a grain boundary diffusion phenomenon [4 - 6]; further highlighting the importance of understanding the actual grain characteristics of the SiC layer. Both historic HTGR fission product release studies and recent experiments at Idaho National Laboratory (INL) [7] have shown that the release of Ag-110m is strongly temperature dependent. Although the maximum normal operating fuel temperature of a HTGR design is in the range of 1000-1250°C, the temperature may reach 1600°C under postulated accident conditions. The aim of this specific study is therefore to determine the magnitude of temperature dependence on SiC grain characteristics, expanding upon initial studies by Van Rooyen et al, [8; 9].

  9. External fuel vaporization study, phase 2

    Science.gov (United States)

    Szetela, E. J.; Chiappetta, L.

    1981-01-01

    An analytical study was conducted to evaluate the effect of variations in fuel properties on the design of an external fuel vaporizaton system. The fuel properties that were considered included thermal stability, critical temperature, enthalpy a critical conditions, volatility, and viscosity. The design parameters that were evaluated included vaporizer weight and the impact on engine requirement such as maintenance, transient response, performance, and altitude relight. The baseline fuel properties were those of Jet A. The variation in thermal stability was taken as the thermal stability variation for Experimental Referee Broad Specification (ERBS) fuel. The results of the analysis indicate that a change in thermal stability equivalent to that of ERBS would increase the vaporization system weight by 20 percent, decrease oprating time between cleaning by 40 percent and make altitude relight more difficult. An increase in fuel critical temperature of 39 K would require a 40 percent increase in vaporization system weight. The assumed increase in enthalpy and volatility would also increase vaporizer weight by 40 percent and make altitude relight extremely difficult. The variation in fuel viscosity would have a negligible effect on the design parameters.

  10. Quantitative liquid and vapor distribution measurements in evaporating fuel sprays using laser-induced exciplex fluorescence

    International Nuclear Information System (INIS)

    Fansler, Todd D; Drake, Michael C; Gajdeczko, Boguslaw; Düwel, Isabell; Koban, Wieland; Zimmermann, Frank P; Schulz, Christof

    2009-01-01

    Fully quantitative two-dimensional measurements of liquid- and vapor-phase fuel distributions (mass per unit volume) from high-pressure direct-injection gasoline injectors are reported for conditions of both slow and rapid vaporization in a heated, high-pressure spray chamber. The measurements employ the coevaporative gasoline-like fluorobenzene (FB)/diethylmethylamine (DEMA)/hexane exciplex tracer/fuel system. In contrast to most previous laser-induced exciplex-fluorescence (LIEF) experiments, the quantitative results here include regions in which liquid and vapor fuel coexist (e.g. near the injector exit). A unique aspect is evaluation of both vapor- and liquid-phase distributions at varying temperature and pressure using only in situ vapor-phase fluorescence calibration measurements at room temperature and atmospheric pressure. This approach draws on recent extensive measurements of the temperature-dependent spectroscopic properties of the FB–DEMA exciplex system, in particular on knowledge of the quantum efficiencies of the vapor-phase and liquid-phase (exciplex) fluorescence. In addition to procedures necessary for quantitative measurements, we discuss corrections for liquid–vapor crosstalk (liquid fluorescence that overlaps the vapor-fluorescence bandpass), the unknown local temperature due to vaporization-induced cooling, and laser-sheet attenuation by scattering and absorption

  11. In situ acetylene reduction activity of Scytonema julianum in Vapor cave (Spain

    Directory of Open Access Journals (Sweden)

    Asencio Antonia Dolores

    2011-01-01

    Full Text Available Nitrogen fixation was measured in situ for the first time by acetylene reduction for a greyish mat composed of Scytonema julianum in cave- like environments. Mat-specific rates (129.9-215.7 nmol C2 H4 m-2 s-1 for daytime fixation and 65.1-120.6 nmol C2 H4 m-2 s-1 for nighttime fixation recorded in the Vapor cave differed considerably due to the energy reserves stored during photosynthesis being exhausted and used in the dark phase. The most influential environmental parameter for nitrogen fixation in the Vapor cave is temperature in the daytime and nighttime fixations. Nitrogen fixation by cyanobacteria may contribute considerably to the overall nitrogen cycle in harsh environments such as caves. Nitrogenase activity in Scytonema julianum was roughly 30 times higher than that of Scytonema mirabile, which also grew in cave environments, which is due to the characteristics of each site. The entrance of Vapour cave (Spain faces SE, measures 0.75 x 0.6 m and opens to shafts of a total depth of 80 m. Its dimensions and environmental conditions (relative humidity up to 100%; maximum temperature, 43oC imply that it is isolated from external influences, and that the microclimate differs substantially from that experienced externally. Nitrogen fixation, photon flux density, relative humidity and temperature in the Vapor cave were taken hourly over a 24-hour period in winter.

  12. Reply to "On Vaporization of liquid Pb-Li eutectic alloy from 1000 K to 1200 K- A high temperature mass spectrometric study"

    Science.gov (United States)

    Jain, Uttam; Mukherjee, Abhishek

    2018-03-01

    This communication is in response to a letter to editor commenting on the authors' earlier paper "Vaporization of liquid Pb-Li eutectic alloy from 1000 K to 1200 K - A high temperature mass spectrometric study".

  13. Measurement and analysis of transient vaporization in oxide fuel materials

    International Nuclear Information System (INIS)

    Gorham-Bergeron, E.; Benson, D.A.

    1978-01-01

    A series of experiments is described in which samples are heated to produce high vapor pressure states in times of 10 -6 to 10 -3 seconds. Experimental measurements of vapor pressures over fresh UO 2 from the pulsed electron beam and pulsed reactor heating tests are presented and compared with other high temperature data. The interpretation of the vapor pressures measured in the tests is discussed in detail. Effects of original sample stoichiometry, chemical interactions with the container and non-equilibrium evaporation due to induced temperature gradients are discussed. Special attention is given to dynamic behavior in rapid heating and vaporization of the oxide due to chemical nonequilibrium. Finally, similar projected reactor experiments on irradiated fuel are described and vapor pressure predictions made using available equilibrium models. A discussion of information accessible from such future tests and its importance is presented

  14. High temperature dielectric properties of (BxNyOz thin films deposited using ion source assisted physical vapor deposition

    Directory of Open Access Journals (Sweden)

    N. Badi

    2015-12-01

    Full Text Available The dielectric integrity has been one of the major obstacle in bringing out capacitor devices with suitable performance characteristics at high temperatures. In this paper, BxNyOz dielectric films for high temperature capacitors solutions are investigated. The films were grown on silicon substrate by using ion source assisted physical vapor deposition technique. The as-grown films were characterized by SEM, XRD, and XPS. The capacitor structures were fabricated using BxNyOz as a dielectric and titanium as metal electrodes. The elaborated devices were subjected to electrical and thermal characterization. They exhibited low electrical loss and very good stability when subjected to high temperature for a prolonged period of time.

  15. Electric conductivity of double fluorides in the systems M1F-Th(U)F4(M1=K, Tl) and M2F2-ThF4(M2=Ca, Sr, Ba)

    International Nuclear Information System (INIS)

    Murin, I.V.; Andreev, A.M.; Amelin, Yu.V.

    1982-01-01

    The temperature dependence of electric conductivity of some double fluorides formed in the systems M 1 F-Th(U)F 4 (M 1 =K, Tl) and M 2 F 2 -ThF 4 (M 2 =Ca, Sr, Ba) as well as UF 3 in a wide temperature range is studied. It is shown that the values of electric conductivity and activation energy of these fluorides depend on the compound structure and cation nature. The temperature electric conductivity dependence for double fluorides with the tysonite structure is close to the lanthanum fluoride dependence. Taking into account low electron electric conductivity component the conclusion is drawn that the investigated compounds can be used as solid electrolytes

  16. A systematic study of atmospheric pressure chemical vapor deposition growth of large-area monolayer graphene.

    Science.gov (United States)

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Chen, Yu; Lin, Yung-Chen; Qu, Yongquan; Bai, Jingwei; Ivanov, Ivan A; Liu, Gang; Huang, Yu; Duan, Xiangfeng

    2012-01-28

    Graphene has attracted considerable interest as a potential material for future electronics. Although mechanical peel is known to produce high quality graphene flakes, practical applications require continuous graphene layers over a large area. The catalyst-assisted chemical vapor deposition (CVD) is a promising synthetic method to deliver wafer-sized graphene. Here we present a systematic study on the nucleation and growth of crystallized graphene domains in an atmospheric pressure chemical vapor deposition (APCVD) process. Parametric studies show that the mean size of the graphene domains increases with increasing growth temperature and CH 4 partial pressure, while the density of domains decreases with increasing growth temperature and is independent of the CH 4 partial pressure. Our studies show that nucleation of graphene domains on copper substrate is highly dependent on the initial annealing temperature. A two-step synthetic process with higher initial annealing temperature but lower growth temperature is developed to reduce domain density and achieve high quality full-surface coverage of monolayer graphene films. Electrical transport measurements demonstrate that the resulting graphene exhibits a high carrier mobility of up to 3000 cm 2 V -1 s -1 at room temperature.

  17. Water vapor absorption in the atmospheric window at 239 GHz

    Science.gov (United States)

    Bauer, A.; Godon, M.; Carlier, J.; Ma, Q.

    1995-01-01

    Absolute absorption rates of pure water vapor and mixtures of water vapor and nitrogen have been measured in the atmospheric window at 239 GHz. The dependence on pressure as well as temperature has been obtained. The experimental data are compared with several theoretical or empirical models, and satisfactory agreement is obtained with the models involving a continuum; in the case of pure water vapor, the continuum contribution based upon recent theoretical developments gives good results. The temperature dependence is stronger than that proposed in a commonly used atmospheric transmission model.

  18. Experiment HFR-B1: A preliminary analysis of the water-vapor injection experiments in capsule 3

    International Nuclear Information System (INIS)

    Myers, B.F.

    1993-01-01

    A preliminary analysis of the response of uranium oxycarbide (UCO) fuel to water vapor addition in capsule 3 of experiment HFR-B1 (HFR-B1/3) has been conducted. The analysis provides an early indication of the behavior of fission gas release under a wider range of water-vapor pressures and of temperatures than heretofore studied. A preliminary analysis of selected aspects of the water-vapor injection tests in capsule 3 of experiment HFR-B1 is presented. The release of fission gas stored in bubbles and the diffusive release of fission-gas atoms are distinguished. The dependence of the release of stored fission gas ( 85m Kr) on water-vapor pressure, P(H 2 O), and temperature were established taking into account the contributing mechanisms of gaseous release, the effect of graphite hydrolysis, and the requirement of consistency with experiment HRB-17 in which similar water-vapor injection tests were conducted. The dependence on P(H 2 O) becomes weaker as temperatures increase above 770 degree C; the activation energy for release of stored-fission gas is 393 kJ/mol. Isorelease curves for the pressure-temperature plane were deduced from a derived functional relation. The stored-fission gas releases as a function of P(H 2 O) at a common temperature for experiments HFR-B1 and HRB-17 differ by a factor of 4; this discrepancy could be attributed to the differences in fission-rate density and neutron flux between the two experiments. Diffusive release of fission gas occurred during and after the release of stored gas. The ratio of diffusive release during water-vapor injection to that prior to injection varied in contrast to the results from HRB-17. The variation was attributed to the practice of injecting water vapor into HFR-B1 before sintering of the fuel, hydrolyzed in the previous test, was completed. The derived activation energy for diffusive release is 23.6 kJ/mol

  19. Experiment HFR-B1: A preliminary analysis of the water-vapor injection experiments in capsule 3

    Energy Technology Data Exchange (ETDEWEB)

    Myers, B.F.

    1993-08-01

    A preliminary analysis of the response of uranium oxycarbide (UCO) fuel to water vapor addition in capsule 3 of experiment HFR-B1 (HFR-B1/3) has been conducted. The analysis provides an early indication of the behavior of fission gas release under a wider range of water-vapor pressures and of temperatures than heretofore studied. A preliminary analysis of selected aspects of the water-vapor injection tests in capsule 3 of experiment HFR-B1 is presented. The release of fission gas stored in bubbles and the diffusive release of fission-gas atoms are distinguished. The dependence of the release of stored fission gas ({sup 85m}Kr) on water-vapor pressure, P(H{sub 2}O), and temperature were established taking into account the contributing mechanisms of gaseous release, the effect of graphite hydrolysis, and the requirement of consistency with experiment HRB-17 in which similar water-vapor injection tests were conducted. The dependence on P(H{sub 2}O) becomes weaker as temperatures increase above 770{degree}C; the activation energy for release of stored-fission gas is 393 kJ/mol. Isorelease curves for the pressure-temperature plane were deduced from a derived functional relation. The stored-fission gas releases as a function of P(H{sub 2}O) at a common temperature for experiments HFR-B1 and HRB-17 differ by a factor of 4; this discrepancy could be attributed to the differences in fission-rate density and neutron flux between the two experiments. Diffusive release of fission gas occurred during and after the release of stored gas. The ratio of diffusive release during water-vapor injection to that prior to injection varied in contrast to the results from HRB-17. The variation was attributed to the practice of injecting water vapor into HFR-B1 before sintering of the fuel, hydrolyzed in the previous test, was completed. The derived activation energy for diffusive release is 23.6 kJ/mol.

  20. The action of uranium hexafluoride on some metallic fluorides (1962); Action de l'hexafluorure d'uranium sur quelques fluorures metalliques (1962)

    Energy Technology Data Exchange (ETDEWEB)

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

    1961-12-15

    A metallic difluoride is inert to UF{sub 6} unless the metal can exist in a higher valency state. In this case, UF{sub 6} acts as an oxidising agent and is transformed into UF{sub 4}. The fluorides of tri- and tetra-valent metals give rise to new compounds when they are maintained at a high temperature (500 deg. C) in the presence of uranium hexachloride vapour. The products obtained are characterized by their X-ray diffraction diagrams. The distributions of the lines of the powder diagrams are very similar to that of U{sub 4}F{sub 17}. Assuming that this resemblance is due to a stacking of identical fluorine atoms, it can be calculated that the corresponding structure is given by the theoretical formulae: MeF{sub 3}, 0,562 UF{sub 6}; MeF{sub 4}, 0,396 UF{sub 6} which are in good agreement with chemical measurements. (author) [French] Un di-fluorure metallique est inerte vis-a-vis de UF{sub 6}, sauf si le metal est susceptible d'exister a une valence plus elevee. Dans ce cas, UF{sub 6} joue le role d'un oxydant et se transforme en UF{sub 4}. Les fluorures de metaux tri et tetravalents donnent naissance a des composes nouveaux quand ils sont maintenus a haute temperature (500 deg. C) en presence de vapeur d'hexafluorure d'uranium. Les produits obtenus sont caracterises par leurs diagrammes de diffraction X. Les distributions de raies des diagrammes de poudre sont tres voisines de celles de U{sub 4}F{sub 17}. En supposant que cette analogie resulte d'un empilement d'ions fluor identique, le calcul conduit aux formules theoriques suivantes: MeF{sub 3}, 0,562 UF{sub 6}; MeF{sub 4}, 0,396 UF{sub 6} en bon accord avec les resultats des dosages chimiques. (auteur)