WorldWideScience

Sample records for oxygen methane krypton

  1. Electron drift velocity measurements in liquid krypton-methane mixtures

    CERN Document Server

    Folegani, M; Magri, M; Piemontese, L

    1999-01-01

    Electron drift velocities have been measured in liquid krypton, pure and mixed with methane at different concentrations (1-10% in volume) versus electric field strength, and a possible effect of methane on electron lifetime has been investigated. While no effect on lifetime could be detected, since lifetimes were in all cases longer than what measurable, a very large increase in drift velocity (up to a factor 6) has been measured.

  2. Oxygen sensitivity of krypton and Lyman-alpha hygrometers

    NARCIS (Netherlands)

    Dijk, van A.; Kohsiek, W.; Bruin, de H.A.R.

    2003-01-01

    The oxygen sensitivity of krypton and Lyman-¿ hygrometers is studied. Using a dewpoint generator and a controlled nitrogen/oxygen flow the extinction coefficients of five hygrometers associated with the third-order Taylor expansion of the Lambert¿Beer law around reference conditions for oxygen and

  3. Oxygen-Methane Thruster

    Science.gov (United States)

    Pickens, Tim

    2012-01-01

    An oxygen-methane thruster was conceived with integrated igniter/injector capable of nominal operation on either gaseous or liquid propellants. The thruster was designed to develop 100 lbf (approximately 445 N) thrust at vacuum conditions and use oxygen and methane as propellants. This continued development included refining the design of the thruster to minimize part count and manufacturing difficulties/cost, refining the modeling tools and capabilities that support system design and analysis, demonstrating the performance of the igniter and full thruster assembly with both gaseous and liquid propellants, and acquiring data from this testing in order to verify the design and operational parameters of the thruster. Thruster testing was conducted with gaseous propellants used for the igniter and thruster. The thruster was demonstrated to work with all types of propellant conditions, and provided the desired performance. Both the thruster and igniter were tested, as well as gaseous propellants, and found to provide the desired performance using the various propellant conditions. The engine also served as an injector testbed for MSFC-designed refractory combustion chambers made of rhenium.

  4. Separation of krypton from carbon dioxide and oxygen with molecular sieves

    International Nuclear Information System (INIS)

    Forsberg, C.W.

    1976-01-01

    Molecular sieves were investigated to separate 1 percent mixtures of krypton in gas streams of a few percent oxygen and 90+ percent carbon dioxide. Such a system will be required to concentrate the krypton gas between radioactive krypton off-gas cleanup systems such as KALC (Krypton Absorption in Liquid Carbon Dioxide) and any krypton gas bottling station. Linde 5A molecular sieves were found capable of selectively removing the CO 2 from the gas stream while partially separating the oxygen from the krypton; i.e., effecting a three-component gas separation. This use of molecular sieves differs from standard practice in two respects. First, the bulk of the gas (greater than 90 percent) is removed by molecular sieves rather than the normal practice of using molecular sieves to remove trace impurities. Second, in a single bed two separations occur simultaneously, CO 2 from other gases and krypton from oxygen. The use of molecular sieves for separating krypton and carbon dioxide is superior to alternatives such as CO 2 freezeout and chemical traps when there are only moderate gas flows and there is a need for very high reliability and ease of maintenance

  5. Oxygen-Methane Thruster, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Orion Propulsion, Inc. proposes to develop an Oxygen and Methane RCS Thruster to advance the technology of alternate fuels. A successful Oxygen/CH4 RCS Thruster will...

  6. Oxygen-Methane Thruster, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Two main innovations will be developed in the Phase II effort that are fundamentally associated with our gaseous oxygen/gaseous methane RCS thruster. The first...

  7. Ebullitive methane emissions from oxygenated wetland streams

    Science.gov (United States)

    Crawford, John T.; Stanley, Emily H.; Spawn, Seth A.; Finlay, Jacques C.; Striegl, Robert G.

    2014-01-01

    Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr−1; over 6400 km2) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle.

  8. Charge state distribution studies of pure and oxygen mixed krypton ECR plasma - signature of isotope anomaly and gas mixing effect.

    Science.gov (United States)

    Kumar, Pravin; Mal, Kedar; Rodrigues, G

    2016-11-01

    We report the charge state distributions of the pure, 25% and 50% oxygen mixed krypton plasma to shed more light on the understanding of the gas mixing and the isotope anomaly [A. G. Drentje, Rev. Sci. Instrum. 63 (1992) 2875 and Y Kawai, D Meyer, A Nadzeyka, U Wolters and K Wiesemann, Plasma Sources Sci. Technol. 10 (2001) 451] in the electron cyclotron resonance (ECR) plasmas. The krypton plasma was produced using a 10 GHz all-permanent-magnet ECR ion source. The intensities of the highly abundant four isotopes, viz. 82 Kr (~11.58%), 83 Kr (~11.49%), 84 Kr (~57%) and 86 Kr (17.3%) up to ~ +14 charge state have been measured by extracting the ions from the plasma and analysing them in the mass and the energy using a large acceptance analyzer-cum-switching dipole magnet. The influence of the oxygen gas mixing on the isotopic krypton ion intensities is clearly evidenced beyond +9 charge state. With and without oxygen mixing, the charge state distribution of the krypton ECR plasma shows the isotope anomaly with unusual trends. The anomaly in the intensities of the isotopes having quite closer natural abundance, viz. 82 Kr, 86 Kr and 83 Kr, 86 Kr is prominent, whereas the intensity ratio of 86 Kr to 84 Kr shows a weak signature of it. The isotope anomaly tends to disappear with increasing oxygen mixing in the plasma. The observed trends in the intensities of the krypton isotopes do not follow the prediction of linear Landau wave damping in the plasma. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  9. Paradox reconsidered: Methane oversaturation in well-oxygenated lake waters

    DEFF Research Database (Denmark)

    Tang, Kam W.; McGinnis, Daniel F.; Frindte, Katharina

    2014-01-01

    The widely reported paradox of methane oversaturation in oxygenated water challenges the prevailing paradigm that microbial methanogenesis only occurs under anoxic conditions. Using a combination of field sampling, incubation experiments, and modeling, we show that the recurring mid-water methane...... peak in Lake Stechlin, northeast Germany, was not dependent on methane input from the littoral zone or bottom sediment or on the presence of known micro-anoxic zones. The methane peak repeatedly overlapped with oxygen oversaturation in the seasonal thermocline. Incubation experiments and isotope...... analysis indicated active methane production, which was likely linked to photosynthesis and/or nitrogen fixation within the oxygenated water, whereas lessening of methane oxidation by light allowed accumulation of methane in the oxygen-rich upper layer. Estimated methane efflux from the surface water...

  10. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters

    Science.gov (United States)

    Milucka, Jana; Kirf, Mathias; Lu, Lu; Krupke, Andreas; Lam, Phyllis; Littmann, Sten; Kuypers, Marcel MM; Schubert, Carsten J

    2015-01-01

    Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes. PMID:25679533

  11. Frozen orientation disorder and rotation excitation in solid mixtures of methane and krypton (neutron diffraction experiments)

    International Nuclear Information System (INIS)

    Grondey, S.

    1986-09-01

    The effect of a statistical replacement of CH 4 molecules by Kr atoms on the rotational states in solid methane has been examined. Obviously the anisotropic molecular interaction (octopole-octopole interaction) is disturbed in a way analogous to magnetic systems with random internal fields. Inelastic neutron scattering experiments on solid mixtures (CH 4 ) 1-x Kr x with 0≤x≤0.35 have been carried out, and simple models have been developed to interpret the spectra. (orig./BHO)

  12. Separation of radioactive krypton from carbon dioxide and oxygen with molecular sieves

    International Nuclear Information System (INIS)

    Forsberg, C.W.

    1977-10-01

    In the reprocessing of HTGR nuclear fuels, the off-gas cleanup system generates a stream containing about 1 percent krypton, 90+ percent CO 2 , and various amounts of O 2 , N 2 , and xenon. The krypton is radioactive and must be separated from the CO 2 before it is bottled or zeolite-encapsulated for final disposal. A series of theoretical and experimental investigations to find the best method for separating CO 2 and krypton under the required conditions showed that 5A molecular sieves near O 0 C and 1.01 x 10 5 Pa (1 atm) provided the most effective separation. Molecular sieves are powerful solid adsorbents for CO 2 but weak adsorbents for krypton. For a typical expected CO 2 -O 2 -krytpon gas mixture, a molecular sieve bed adsorbs the CO 2 , allows the O 2 to pass freely through the bed, and concentrates the krypton before it exits the bed. The process selected and investigated is called frontal analysis gas chromatography

  13. Ion measurements in premixed methane-oxygen flames

    KAUST Repository

    Alquaity, Awad; Hourani, Nadim; Chahine, May; Selim, Hatem; Sarathy, Mani; Farooq, Aamir

    2014-01-01

    Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry

  14. 氪气产品氧含量超标的分析及处理%Analysis and treatment of exceedance of oxygen content in gaseous krypton product

    Institute of Scientific and Technical Information of China (English)

    葛军; 陈颂; 高波

    2012-01-01

    During operation of krypton xenon fine extraction unit, the poor heat exchange effect of heat exchanger before molecular sieve absorber and the leakage of inlet of molecular sieve absorber leads to exceedance of oxygen content in gaseous krypton product. After elimination troubles with corresponding corrective measures, the krypton xenon fine extraction unit steadily runs and the quality of gaseous krypton product conforms to state standards. The flow process of krypton xenon fine extraction unit is briefed, the cause analysis, treatment scheme and its effects are detailed and finally the lessons are summarized.%在氪氙精提取装置运行过程中,由于分子筛吸附器前的换热器换热效果不理想和分子筛吸附器入口泄漏等原因,导致氪气产品中的氧含量超标。采取相应措施排除故障后,保证了氪氙精提取装置的稳定运行,使氪气产品质量达到了国家标准的要求。简介氪氙精提取装置的流程,详细介绍原因分析过程和处理方案的实施及其效果,最后总结由此获得的体会。

  15. Methane Post-Processing for Oxygen Loop Closure

    Science.gov (United States)

    Greenwood, Zachary W.; Abney, Morgan B.; Miller, Lee

    2016-01-01

    State-of-the-art United States Atmospheric Revitalization carbon dioxide (CO2) reduction is based on the Sabatier reaction process, which recovers approximately 50% of the oxygen (O2) from crew metabolic CO2. Oxygen recovery from carbon dioxide is constrained by the limited availability of reactant hydrogen. Post-processing of methane to recover hydrogen with the Umpqua Research Company Plasma Pyrolysis Assembly (PPA) has the potential to further close the Atmospheric Revitalization oxygen loop. The PPA decomposes methane into hydrogen and hydrocarbons, predominantly acetylene, and a small amount of solid carbon. The hydrogen must then be purified before it can be recycled for additional oxygen recovery. Long duration testing and evaluation of a four crew-member sized PPA and a discussion of hydrogen recycling system architectures are presented.

  16. Plasma Methane Pyrolysis for Spacecraft Oxygen Loop Closure

    Science.gov (United States)

    Greenwood, Z. W.

    2018-01-01

    Life support is a critical function of any crewed space vehicle or habitat. Human life support systems on the International Space Station (ISS) include a number of atmosphere revitalization (AR) technologies to provide breathable air and a comfortable living environment to the crew. The Trace Contaminant Control System removes harmful volatile organic compounds and other trace contaminants from the circulating air. The Carbon Dioxide Removal Assembly (CDRA) removes metabolic carbon dioxide (CO2) and returns air to the cabin. Humidity is kept at comfortable levels by a number of condensing heat exchangers. The Oxygen Generation Assembly (OGA) electrolyzes water to produce oxygen for the crew and hydrogen (H2) as a byproduct. A Sabatier reaction-based CO2 Reduction Assembly (CRA) was launched to the ISS in 2009 and became fully operational in June 2011.The CRA interfaces with both the OGA and CDRA. Carbon dioxide from the CDRA is compressed and stored in tanks until hydrogen is available from OGA water electrolysis. When the OGA is operational and there is CO2 available, the CRA is activated and produces methane and water via the Sabatier reaction shown in Equation 1... One approach to achieve these higher recovery rates builds upon the ISS AR architecture and includes adding a methane post-processor to recover H2 from CRA methane. NASA has been developing the Plasma Pyrolysis Assembly (PPA) to fill the role of a methane post-processor.

  17. Ion measurements in premixed methane-oxygen flames

    KAUST Repository

    Alquaity, Awad

    2014-07-25

    Ions are formed as a result of chemi-ionization processes in combustion systems. Recently, there has been an increasing interest in understanding flame ion chemistry due to the possible application of external electric fields to reduce emissions and improve combustion efficiency by active control of combustion process. In order to predict the effect of external electric fields on combustion plasma, it is critical to gain a good understanding of the flame ion chemistry. In this work, a Molecular Beam Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry on equivalence ratio of premixed flames. The relative ion concentration profiles are compared qualitatively with previous methane-oxygen studies and show good agreement. The relative ion concentration data obtained in the present study can be used to validate and improve ion chemistry models for methane-oxygen flames.

  18. Seasonal Oxygen Dynamics in a Thermokarst Bog in Interior Alaska: Implications for Rates of Methane Oxidation

    Science.gov (United States)

    Neumann, R. B.; Moorberg, C.; Wong, A.; Waldrop, M. P.; Turetsky, M. R.

    2015-12-01

    Methane is a potent greenhouse gas, and wetlands represent the largest natural source of methane to the atmosphere. However, much of the methane generated in anoxic wetlands never gets emitted to the atmosphere; up to >90% of generated methane can get oxidized to carbon dioxide. Thus, oxidation is an important methane sink and changes in the rate of methane oxidation can affect wetland methane emissions. Most methane is aerobically oxidized at oxic-anoxic interfaces where rates of oxidation strongly depend on methane and oxygen concentrations. In wetlands, oxygen is often the limiting substrate. To improve understanding of belowground oxygen dynamics and its impact on methane oxidation, we deployed two planar optical oxygen sensors in a thermokarst bog in interior Alaska. Previous work at this site indicated that, similar to other sites, rates of methane oxidation decrease over the growing season. We used the sensors to track spatial and temporal patterns of oxygen concentrations over the growing season. We coupled these in-situ oxygen measurements with periodic oxygen injection experiments performed against the sensor to quantify belowground rates of oxygen consumption. We found that over the season, the thickness of the oxygenated water layer at the peatland surface decreased. Previous research has indicated that in sphagnum-dominated peatlands, like the one studied here, rates of methane oxidation are highest at or slightly below the water table. It is in these saturated but oxygenated locations that both methane and oxygen are available. Thus, a seasonal reduction in the thickness of the oxygenated water layer could restrict methane oxidation. The decrease in thickness of the oxygenated layer coincided with an increase in the rate of oxygen consumption during our oxygen injection experiments. The increase in oxygen consumption was not explained by temperature; we infer it was due to an increase in substrate availability for oxygen consuming reactions and

  19. New insights into methane-oxygen ion chemistry

    KAUST Repository

    Alquaity, Awad B.S.; Chen, Bingjie; Han, Jie; Selim, Hatem; Belhi, Memdouh; Karakaya, Yasin; Kasper, Tina; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2016-01-01

    External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.

  20. New insights into methane-oxygen ion chemistry

    KAUST Repository

    Alquaity, Awad B.S.

    2016-06-15

    External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.

  1. Liquid Oxygen/Liquid Methane Integrated Power and Propulsion

    Science.gov (United States)

    Banker, Brian; Ryan, Abigail

    2016-01-01

    The proposed paper will cover ongoing work at the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) on integrated power and propulsion for advanced human exploration. Specifically, it will present findings of the integrated design, testing, and operational challenges of a liquid oxygen / liquid methane (LOx/LCH4) propulsion brassboard and Solid Oxide Fuel Cell (SOFC) system. Human-Mars architectures point to an oxygen-methane economy utilizing common commodities, scavenged from the planetary atmosphere and soil via In-Situ Resource Utilization (ISRU), and common commodities across sub-systems. Due to the enormous mass gear-ratio required for human exploration beyond low-earth orbit, (for every 1 kg of payload landed on Mars, 226 kg will be required on Earth) increasing commonality between spacecraft subsystems such as power and propulsion can result in tremendous launch mass and volume savings. Historically, propulsion and fuel cell power subsystems have had little interaction outside of the generation (fuel cell) and consumption (propulsion) of electrical power. This was largely due to a mismatch in preferred commodities (hypergolics for propulsion; oxygen & hydrogen for fuel cells). Although this stove-piped approach benefits from simplicity in the design process, it means each subsystem has its own tanks, pressurization system, fluid feed system, etc. increasing overall spacecraft mass and volume. A liquid oxygen / liquid methane commodities architecture across propulsion and power subsystems would enable the use of common tankage and associated pressurization and commodity delivery hardware for both. Furthermore, a spacecraft utilizing integrated power and propulsion could use propellant residuals - propellant which could not be expelled from the tank near depletion due to hydrodynamic considerations caused by large flow demands of a rocket engine - to generate power after all propulsive maneuvers are complete thus utilizing

  2. Microbial methane production in oxygenated water column of an oligotrophic lake

    Science.gov (United States)

    Grossart, Hans-Peter; Frindte, Katharina; Dziallas, Claudia; Eckert, Werner; Tang, Kam W.

    2011-01-01

    The prevailing paradigm in aquatic science is that microbial methanogenesis happens primarily in anoxic environments. Here, we used multiple complementary approaches to show that microbial methane production could and did occur in the well-oxygenated water column of an oligotrophic lake (Lake Stechlin, Germany). Oversaturation of methane was repeatedly recorded in the well-oxygenated upper 10 m of the water column, and the methane maxima coincided with oxygen oversaturation at 6 m. Laboratory incubations of unamended epilimnetic lake water and inoculations of photoautotrophs with a lake-enrichment culture both led to methane production even in the presence of oxygen, and the production was not affected by the addition of inorganic phosphate or methylated compounds. Methane production was also detected by in-lake incubations of lake water, and the highest production rate was 1.8–2.4 nM⋅h−1 at 6 m, which could explain 33–44% of the observed ambient methane accumulation in the same month. Temporal and spatial uncoupling between methanogenesis and methanotrophy was supported by field and laboratory measurements, which also helped explain the oversaturation of methane in the upper water column. Potentially methanogenic Archaea were detected in situ in the oxygenated, methane-rich epilimnion, and their attachment to photoautotrophs might allow for anaerobic growth and direct transfer of substrates for methane production. Specific PCR on mRNA of the methyl coenzyme M reductase A gene revealed active methanogenesis. Microbial methane production in oxygenated water represents a hitherto overlooked source of methane and can be important for carbon cycling in the aquatic environments and water to air methane flux. PMID:22089233

  3. Methanogenesis in oxygenated soils is a substantial fraction of wetland methane emissions

    Energy Technology Data Exchange (ETDEWEB)

    Angle, Jordan C.; Morin, Timothy H.; Solden, Lindsey M.; Narrowe, Adrienne B.; Smith, Garrett J.; Borton, Mikayla A.; Rey-Sanchez, Camilo; Daly, Rebecca A.; Mirfenderesgi, Golnazalsdat; Hoyt, David W.; Riley, William J.; Miller, Christopher S.; Bohrer, Gil; Wrighton, Kelly C.

    2017-11-16

    The current paradigm, widely incorporated in soil biogeochemical models, is that microbial methanogenesis can only occur in anoxic habitats1-4. In contrast, here porewater and greenhouse-gas flux measurements show clear evidence for methane production in well-oxygenated soils from a freshwater wetland. A comparison of oxic to anoxic soils revealed up to ten times greater methane production and nine times more methanogenesis activity in oxygenated soils. Metagenomic and metatranscriptomic sequencing recovered the first near complete genomes for a novel methanogen species, and showed acetoclastic production from this organism was the dominant methanogenesis pathway in oxygenated soils. This organism, Candidatus Methanosaeta oxydurans, is prevalent across methane emitting ecosystems, suggesting a global significance. Moreover, in this wetland, we estimated that a dominant fraction of methane fluxes could be attributed to methanogenesis in oxygenated soils. Together our findings challenge a widely-held assumption about methanogenesis, with significant ramifications for global methane estimates and Earth system modeling.

  4. Spectroscopic studies of ozone in cryosolutions: FT-IR spectra of 16O3 in liquid nitrogen, oxygen, argon and krypton

    Science.gov (United States)

    Bulanin, Kirill M.; Bulanin, Michael O.; Rudakova, Aida V.; Kolomijtsova, Tatiana D.; Shchepkin, Dmitrij N.

    2018-03-01

    We have measured and interpreted the IR spectra of ozone dissolved in liquid nitrogen, oxygen, argon, and krypton in the 650-4700 cm-1 spectral region at 79-117 K. Frequency shifts, band intensities and bandshapes of 22 spectral features of soluted ozone were analyzed. The bands of the A1 symmetry have a complex contour and possess an excess intensity with respect to the value of the purely vibrational transition moment. It was found that this effect is related to the manifestation of the Coriolis interaction. The bandshape distortion manifests itself as an additional intensity from the side of the B1 symmetry band being an intensity source in the case of the Coriolis interaction.

  5. Capture and immobilization of krypton-85

    International Nuclear Information System (INIS)

    Whitmell, D.S.; Geens, L.; Penzhorn, R.D.; Smith, M.J.S.

    1985-01-01

    It may become necessary to contain the krypton-85 released from nuclear fuel during reprocessing in order to reduce the exposure to the local population and the radioactive background throughout the world. A brief description is given of studies being carried out in the Indirect Action Programme. The separation of krypton from other off-gases by cryogenic distillation in the presence of oxygen is being studied at SCK/CEN Mol, together with the behavior of ozone in the distillation column. Two processes for the immobilization of krypton in solid forms have been successfully developed and demonstrated. At KfK Karlsruhe, krypton is encapsulated in vitrified zeolites; at AERE Harwell, krypton is immobilized within a metallic matrix. These processes offer excellent gas retention and either could be adopted for a reprocessing plant

  6. Thermo-Catalytic Ignition of Cryogenic Oxygen-Methane, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Liquid oxygen and methane propellants for in space chemical propulsion of future space exploration vehicles is desired for increased performance and elimination of...

  7. Combustion of methane-oxygen and methane-oxygen-CFC mixtures initiated by a high-current slipping surface discharge

    International Nuclear Information System (INIS)

    Kossyi, I.A.; Silakov, V.P.; Tarasova, N.M.

    2001-01-01

    Results are presented from experimental studies of the destruction of chlorofluorocarbon (CF 2 Cl 2 ) molecules in a methane-oxygen (air) gas mixture whose combustion is initiated by a high-current slipping surface discharge. It is found that a three-component CH 4 + O 2 (air)+ CF 2 Cl 2 gas mixture (even with a considerable amount of the third component) demonstrates properties of explosive combustion involving chain reactions that are typical of two-component CH 4 + O 2 mixtures. Experiments show the high degree of destruction (almost complete decomposition) of chlorofluorocarbons contained in the mixture during one combustion event. The combustion dynamics is studied. It is shown that the combustion initiated by a slipping surface discharge has a number of characteristic features that make it impossible to identify the combustion dynamics with the formation of a combustion or detonation wave. The features of the effects observed can be related to intense UV radiation produced by a pulsed high-current surface discharge

  8. Investigating the effects of critical phenomena in premixed methane-oxygen flames at cryogenic conditions

    Science.gov (United States)

    Gopal, Abishek; Yellapantula, Shashank; Larsson, Johan

    2017-11-01

    Methane is increasingly becoming viable as a rocket fuel in the latest generation of launch vehicles. In liquid rocket engines, fuel and oxidizer are injected under cryogenic conditions into the combustion chamber. At high pressures, typical of rocket combustion chambers, the propellants exist in supercritical states where the ideal gas thermodynamics are no longer valid. We investigate the effects of real-gas thermodynamics on transcritical laminar premixed methane-oxygen flames. The effect of the real-gas cubic equations of state and high-pressure transport properties on flame dynamics is presented. We also study real-gas effects on the extinction limits of the methane-oxygen flame.

  9. Syngas Generation from Methane Using a Chemical-Looping Concept: A Review of Oxygen Carriers

    Directory of Open Access Journals (Sweden)

    Kongzhai Li

    2013-01-01

    Full Text Available Conversion of methane to syngas using a chemical-looping concept is a novel method for syngas generation. This process is based on the transfer of gaseous oxygen source to fuel (e.g., methane by means of a cycling process using solid oxides as oxygen carriers to avoid direct contact between fuel and gaseous oxygen. Syngas is produced through the gas-solid reaction between methane and solid oxides (oxygen carriers, and then the reduced oxygen carriers can be regenerated by a gaseous oxidant, such as air or water. The oxygen carrier is recycled between the two steps, and the syngas with a ratio of H2/CO = 2.0 can be obtained successively. Air is used instead of pure oxygen allowing considerable cost savings, and the separation of fuel from the gaseous oxidant avoids the risk of explosion and the dilution of product gas with nitrogen. The design and elaboration of suitable oxygen carriers is a key issue to optimize this method. As one of the most interesting oxygen storage materials, ceria-based and perovskite oxides were paid much attention for this process. This paper briefly introduced the recent research progresses on the oxygen carriers used in the chemical-looping selective oxidation of methane (CLSOM to syngas.

  10. Study on Characteristics of Co-firing Ammonia/Methane Fuels under Oxygen Enriched Combustion Conditions

    Science.gov (United States)

    Xiao, Hua; Wang, Zhaolin; Valera-Medina, Agustin; Bowen, Philip J.

    2018-06-01

    Having a background of utilising ammonia as an alternative fuel for power generation, exploring the feasibility of co-firing ammonia with methane is proposed to use ammonia to substitute conventional natural gas. However, improvement of the combustion of such fuels can be achieved using conditions that enable an increase of oxygenation, thus fomenting the combustion process of a slower reactive molecule as ammonia. Therefore, the present study looks at oxygen enriched combustion technologies, a proposed concept to improve the performance of ammonia/methane combustion. To investigate the characteristics of ammonia/methane combustion under oxygen enriched conditions, adiabatic burning velocity and burner stabilized laminar flame emissions were studied. Simulation results show that the oxygen enriched method can help to significantly enhance the propagation of ammonia/methane combustion without changing the emission level, which would be quite promising for the design of systems using this fuel for practical applications. Furthermore, to produce low computational-cost flame chemistry for detailed numerical analyses for future combustion studies, three reduced combustion mechanisms of the well-known Konnov's mechanism were compared in ammonia/methane flame simulations under practical gas turbine combustor conditions. Results show that the reduced reaction mechanisms can provide good results for further analyses of oxygen enriched combustion of ammonia/methane. The results obtained in this study also allow gas turbine designers and modellers to choose the most suitable mechanism for further combustion studies and development.

  11. Krypton purification (1961); Purification du krypton (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Larher, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Institut Fourier, 38 - Grenoble (France)

    1961-07-01

    The amount of xenon in otherwise very pure krypton can be reduced from 1.5 to 0.0025 per cent approximately by passage through an activated carbon column at dry-ice temperature. The circulation of the krypton is effected by condensing at -196 deg. C and then evaporating. (author) [French] Le taux de xenon dans du krypton par ailleurs tres pur est ramene de 1,5 pour cent a 0,0025 pour cent environ au cours d'un passage a travers une colonne de charbon actif a la temperature de la carboglace. La circulation du krypton se fait par condensation a -196 deg. C, puis evaporation. (auteur)

  12. Radioactive krypton gas separation

    International Nuclear Information System (INIS)

    Martin, J.R.

    1976-01-01

    Radioactive krypton is separated from a gas mixture comprising nitrogen and traces of carbon dioxide and radioactive krypton by selective adsorption and then cryogenic distillation of the prepurified gas against nitrogen liquid to produce krypton bottoms concentrate liquid, using the nitrogen gas from the distillation for two step purging of the adsorbent. 16 Claims, 8 Drawing Figures

  13. Steady state operation of the first cryogenic column in a krypton separation system

    International Nuclear Information System (INIS)

    von Ammon, R.; Bumiller, W.; Hutter, E.; Neffe, G.

    1981-01-01

    Recent results obtained during the operation of the inactive test unit KRETA for the cryogenic separation of krypton from simulated reprocessing off-gases are presented. The first rectification column of this unit was modified by shortening its lower part from 18 to 8 practical plates and placing the feed point into the warmer, krypton-rich section. Two essential results were thus achieved: plugging by desubliming xenon was not observed even at xenon feed concentrations as high as 1 vol.-%; and, accumulation of oxygen was much lower than in the column version used previously, thus reducing the potential hazard by ozone formation drastically. The accumulation of methane, however, was found to be high, in agreement with calculations

  14. Methane oxidation and formation of EPS in compost: effect of oxygen concentration

    International Nuclear Information System (INIS)

    Wilshusen, J.H.; Hettiaratchi, J.P.A.; Visscher, A. de; Saint-Fort, R.

    2004-01-01

    Oxygen concentration plays an important role in the regulation of methane oxidation and the microbial ecology of methanotrophs. However, this effect is still poorly quantified in soil and compost ecosystems. The effect of oxygen on the formation of exopolymeric substances (EPS) is as yet unknown. We studied the effect of oxygen on the evolution of methanotrophic activity. At both high and low oxygen concentrations, peak activity was observed twice within a period of 6 months. Phospholipid fatty acid analysis showed that there was a shift from type I to type II methanotrophs during this period. At high oxygen concentration, EPS production was about 250% of the amount at low oxygen concentration. It is hypothesized that EPS serves as a carbon cycling mechanism for type I methanotrophs when inorganic nitrogen is limiting. Simultaneously, EPS stimulates nitrogenase activity in type II methanotrophs by creating oxygen-depleted zones. The kinetic results were incorporated in a simulation model for gas transport and methane oxidation in a passively aerated biofilter. Comparison between the model and experimental data showed that, besides acting as a micro-scale diffusion barrier, EPS can act as a barrier to macro-scale diffusion, reducing the performance of such biofilters. - 1.5% oxygen resulted in a slightly higher and more stable methane oxidation activity

  15. Analysis of flammability limits for the liquefaction process of oxygen-bearing coal-bed methane

    International Nuclear Information System (INIS)

    Li, Q.Y.; Wang, L.; Ju, Y.L.

    2011-01-01

    Highlights: → A novel liquefaction and distillation process is designed for oxygen bearing coal-bed methane. → Oxygen contained in coal-bed methane is removed in distillation process. → Flammability limits are analyzed for the whole operation process. → We find explosion hazard may exist in distillation tower. → Effective measures are proposed to ensure the operation safety in distillation tower. - Abstract: A novel liquefaction and distillation process has been proposed and designed for the typical oxygen-bearing coal-bed methane (CBM), in which the impurities of the oxygen and nitrogen components are removed in the distillation column. The flammability limit theory combining with HYSYS simulation results are employed to analyze and calculate the flammability limits and the results indicate that no flammability hazard exists in the stages of compression, liquefaction and throttling. However, flammability hazard exists at the top the distillation column because the methane mole fraction decreases to the value below the upper flammability limit (UFL). The safety measures of initially removing oxygen content from the feed gas combining with the control of the bottom flowrate (flowrate of the liquid product at column bottom) are proposed to ensure the operation safety of the liquefaction process. The results reveal that the operation safety of the whole process can be guaranteed, together with high methane recovery rate and high purity of the liquid product. The applicability of the liquefaction process has also been analyzed in this paper. The simulation results can offer references for the separation of oxygen from CBM, the analysis of flammability limits and the safety measures for the whole process.

  16. Catalytic reforming of methane to syngas in an oxygen-permeative membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Urano, Takeshi; Kubo, Keiko; Saito, Tomoyuki; Hitomi, Atsushi, E-mail: turano@jp.tdk.com [Materials and Process Development Center, TDK Corporation 570-2, Matsugashita, Minamihatori, Narita, Chiba 286-8588 (Japan)

    2011-05-15

    For fuel cell applications, partial oxidative reforming of methane to syngas, hydrogen and carbon monoxide, was performed via a dense oxygen-permeative ceramic membrane composed by both ionic and electronic conductive materials. The modification of Ni-based catalyst by noble metals was investigated to increase oxygen permeation flux and decrease carbon deposition during reforming reaction. The role of each component in catalyst was also discussed.

  17. Krypton oxides under pressure

    OpenAIRE

    Zaleski-Ejgierd, Patryk; Łata, Paweł

    2015-01-01

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300?GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamical...

  18. Activity of type i methanotrophs dominates under high methane concentration: Methanotrophic activity in slurry surface crusts as influenced by methane, oxygen, and inorganic nitrogen

    DEFF Research Database (Denmark)

    Duan, Yun Feng; Reinsch, Sabine; Ambus, Per

    2017-01-01

    Livestock slurry is a major source of atmospheric methane (CH4), but surface crusts harboring methane-oxidizing bacteria (MOB) could mediate against CH4 emissions. This study examined conditions for CH4 oxidation by in situ measurements of oxygen (O2) and nitrous oxide (N2O), as a proxy for inorg......Livestock slurry is a major source of atmospheric methane (CH4), but surface crusts harboring methane-oxidizing bacteria (MOB) could mediate against CH4 emissions. This study examined conditions for CH4 oxidation by in situ measurements of oxygen (O2) and nitrous oxide (N2O), as a proxy...... for inorganic N transformations, in intact crusts using microsensors. This was combined with laboratory incubations of crust material to investigate the effects of O2, CH4, and inorganic N on CH4 oxidation, using 13CH4 to trace C incorporation into lipids of MOB. Oxygen penetration into the crust was 2 to 14 mm...

  19. Methane anomalies in the oxygenated upper waters of the central Baltic Sea associated with zooplankton abundance

    Science.gov (United States)

    Schmale, Oliver; Wäge, Janine; Morholz, Volker; Rehder, Gregor; Wasmund, Norbert; Gräwe, Ulf; Labrenz, Matthias; Loick-Wilde, Natalie

    2017-04-01

    Apart from the sediment as the dominant source of methane in the aquatic realm the process of methane production in well-oxygenated waters has received considerable attention during the last years. The paradox of methane accumulation in these relatively shallow waters, commonly termed as "oceanic methane paradox", has been sporadically observed in lakes as well as in marine ecosystems like the Gulf of Mexico, the Black Sea, the Baltic Sea, Arctic waters or above the continental shelf off the coast of Spain and Africa. Even if this phenomenon has been described in the literature over the last decades, the potential sources of shallow methane accumulation are still controversially discussed. We report on methane enrichments that were observed during summer in the upper water column of the Gotland Basin, central Baltic Sea. In the eastern part of the basin methane concentrations just below the thermocline (in about 30 m water depth) varied between 15 and 77 nM, in contrast to the western part of the basin where no methane enrichments could be detected. Stable carbon isotope ratios of methane (delta 13C-CH4 of -67.6‰) clearly indicated its in situ biogenic origin. This is supported by clonal sequences from the depth with high methane concentrations in the eastern Gotland Basin, which cluster with the clade Methanomicrobiacea, a family of methanogenic Archaea. Hydroacoustic observation in combination with plankton net tows displayed a seston enrichment (size >100 micro meter) in a layer between 30-50 m depth. The dominant species in the phytoplankton, Dinophysis norvegica, was concentrated at 10-20 m depth, and showed higher concentrations in the eastern Gotland Basin in comparison with the western part of the basin. In contrast to the western Gotland Basin, the zooplankton community in the eastern part was dominated by the copepod species Temora longicornis. Laboratory incubations of a T. longicornis dominated seston fraction (>100 micro meter) sampled in the depth

  20. Effect of the surface oxygen groups on methane adsorption on coals

    Energy Technology Data Exchange (ETDEWEB)

    Hao Shixiong [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Department of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Wen Jie [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Yu Xiaopeng [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Department of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Chu Wei, E-mail: chuwei1965_scu@yahoo.com [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer We modified one coal with H{sub 2}O{sub 2}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and HNO{sub 3} respectively, to prepare coal samples with different surface properties. Black-Right-Pointing-Pointer The oxygen groups on coal surface were characterized by XPS. Black-Right-Pointing-Pointer The textures of the coal samples were investigated by N{sub 2} adsorption at 77 K. Black-Right-Pointing-Pointer The adsorption behaviors were measured by volumetric method. Black-Right-Pointing-Pointer There was a negative correlation between methane saturated adsorption capacity and the O{sub total}/C{sub total}. - Abstract: To investigate the influence of surface oxygen groups on methane adsorption on coals, one bituminous coal was modified with H{sub 2}O{sub 2}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and HNO{sub 3} respectively, to prepare coal samples with different surface properties. The oxygen groups on coal surface were characterized by X-ray photoelectron spectroscopy (XPS). The textures of the coal samples were investigated by N{sub 2} adsorption at 77 K. Their surface morphologies were analyzed by scanning electron microscopy (SEM). The methane adsorption behaviors of these coal samples were measured at 303 K in pressure range of 0-5.3 MPa by volumetric method. The adsorption data of methane were fitted to the Langmuir model and Dubinin-Astakhov (D-A) model. The fitting results showed that the D-A model fitted the isotherm data better than the Langmuir model. It was observed that there was, in general, a positive correlation between the methane saturated adsorption capacity and the micropore volume of coals while a negative correlation between methane saturated adsorption capacity and the O{sub total}/C{sub total}. The methane adsorption capacity was determined by the coal surface chemistry when the microporosity parameters of two samples were similar. Coal with a higher amount of oxygen surface groups, and consequently with a less

  1. Krypton purification (1961)

    International Nuclear Information System (INIS)

    Larher, Y.

    1961-01-01

    The amount of xenon in otherwise very pure krypton can be reduced from 1.5 to 0.0025 per cent approximately by passage through an activated carbon column at dry-ice temperature. The circulation of the krypton is effected by condensing at -196 deg. C and then evaporating. (author) [fr

  2. The design of a PC-based real-time system for monitoring Methane and Oxygen concentration in biogas production

    Science.gov (United States)

    Yantidewi, M.; Muntini, M. S.; Deta, U. A.; Lestari, N. A.

    2018-03-01

    Limited fossil fuels nowadays trigger the development of alternative energy, one of which is biogas. Biogas is one type of bioenergy in the form of fermented gases of organic materials such as animal waste. The components of gases present in biogas and affect the biogas production are various, such as methane and oxygen. The biogas utilization will be more optimal if both gases concentration (in this case is methane and oxygen concentration) can be monitored. Therefore, this research focused on designing the monitoring system of methane and oxygen concentration in biogas production in real-time. The results showed that the instrument system was capable of monitoring and recording the data of gases (methane and oxygen) concentration in biogas production in every second.

  3. Structural design of liquid oxygen/liquid methane robotic lander JANUS

    Science.gov (United States)

    Chaidez, Mariana

    As the attempt to send humans to Mars has gained momentum in the last decade, the need to find alternative propellants that are safer, less toxic, and yields a better performance has become apparent [1]. Liquid methane and oxygen have emerged as a suitable alternative. In addition, the incorporation of liquid methane/liquid oxygen into the propulsion system has demonstrated an increase in engine performance, as well as a reduction in the volume, size and complexity of the propulsion system. In an attempt to further understand the technologies that are possible to develop using liquid oxygen (LO 2) and liquid methane (LCH4), a preliminary design of a robotic lander JANUS is being completed by the Center for Space Exploration and Technology Research (cSTER). The structural design of the vehicle is important because it acts as the skeleton of the vehicle and dictates the maneuverability of the robotic lander. To develop the structure of the robotic lander, six different design vehicle concepts with varying tank configurations were considered. Finite Element Analysis (FEA) was completed on each model to optimize each vehicle. Trade studies were completed to choose the best design for JANUS. Upon completion of the trade studies the design for the first prototype of JANUS was initiated in which the tank and thrust modules were designed. This thesis will describe the design process for the structural design of the JANUS.

  4. Radioactive kryptonates in the analysis of environmental samples

    International Nuclear Information System (INIS)

    Tolgyessy, J.

    1986-01-01

    The term ''radioactive Kryptonates'' is used for substances into which atoms or ions of the radioactive nuclide 85 Kr are incorporated. The basis of the use of radioactive Kryptonates in analytical chemistry is that during a chemical reaction the crystalline lattice of the kryptonated carrier is destroyed, the carrier consumed, and the radioactive krypton released (radio-release method). Analysis can be made with a calibration curve or by comparison with a standard. Radio-release methods with the aid of radioactive Kryptonates as analytical reagents are very useful for the analysis of environmental samples, e.g. for the determination of air pollutants (ozone, sulphur dioxide, fluorine, hydrogen fluoride, mercury); and water pollutants (oxygen, dichromate, vanadium, hydrochloric acid, sulphur dioxide). (author)

  5. Krypton oxides under pressure.

    Science.gov (United States)

    Zaleski-Ejgierd, Patryk; Lata, Pawel M

    2016-02-02

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds.

  6. Krypton recovery from reprocessing off-gases by cryogenic distillation

    International Nuclear Information System (INIS)

    Geens, L.P.; Goossens, W.R.A.; Marien, J.

    1987-01-01

    With the financial support of the C.E.C., krypton recovery by cryogenic distillation in presence of oxygen was investigated. Both oxygen and ozone behavior in the cryodistillation unit were observed. The ozone decay in the rectification column was studied in absence and in presence of a radiation source. Additionally a demonstration run with krypton-85 was performed. Experiments with different oxygen concentrations up to 21% volume in the feed gas were carried out. The oxygen was enriched up to 85% volume in a zone between the krypton layer and the entrance of the rectification column. No oxygen was found in the bottom product. On the other hand, the ozone accumulated in that bottom product. The decay of ozone in the bottom liquid was measured in absence and in presence of a 500 Ci thulium-170 source. Without the radiation source, it took almost 30 days to observe a decay from 0.90% volume to 0.45% volume. The decay rate decreased with decreasing ozone concentration. In presence of the 500 Ci thulium-170, a constant decay rate of 0.24% volume per day was measured. Finally, a demonstration run with 100 Ci krypton-85 was performed in the cryodistillation unit, with air as feed gas. The krypton-85 was fed at a concentration of 30 mCih -1 until the total krypton inventory of the rectification column amounted to 40-45 Ci. The active run had a duration of 900 hours, during which no operational problems occurred. (orig.)

  7. Enhanced activity and stability of La-doped CeO2 monolithic catalysts for lean-oxygen methane combustion.

    Science.gov (United States)

    Zhu, Wenjun; Jin, Jianhui; Chen, Xiao; Li, Chuang; Wang, Tonghua; Tsang, Chi-Wing; Liang, Changhai

    2018-02-01

    Effective utilization of coal bed methane is very significant for energy utilization and environment protection. Catalytic combustion of methane is a promising way to eliminate trace amounts of oxygen in the coal bed methane and the key to this technology is the development of high-efficiency catalysts. Herein, we report a series of Ce 1-x La x O 2-δ (x = 0-0.8) monolithic catalysts for the catalytic combustion of methane, which are prepared by citric acid method. The structural characterization shows that the substitution of La enhance the oxygen vacancy concentration and reducibility of the supports and promote the migration of the surface oxygen, as a result improve the catalytic activity of CeO 2 . M-Ce 0.8 La 0.2 O 2-δ (monolithic catalyst, Ce 0.8 La 0.2 O 2-δ coated on cordierite honeycomb) exhibits outstanding activity for methane combustion, and the temperature for 10 and 90% methane conversion are 495 and 580 °C, respectively. Additionally, Ce 0.8 La 0.2 O 2-δ monolithic catalyst presents excellent stability at high temperature. These Ce 1-x La x O 2-δ monolithic materials with a small amount of La incorporation therefore show promises as highly efficient solid solution catalysts for lean-oxygen methane combustion. Graphical abstract ᅟ.

  8. Design of a 500 lbf liquid oxygen and liquid methane rocket engine for suborbital flight

    Science.gov (United States)

    Trillo, Jesus Eduardo

    Liquid methane (LCH4)is the most promising rocket fuel for our journey to Mars and other space entities. Compared to liquid hydrogen, the most common cryogenic fuel used today, methane is denser and can be stored at a more manageable temperature; leading to more affordable tanks and a lighter system. The most important advantage is it can be produced from local sources using in-situ resource utilization (ISRU) technology. This will allow the production of the fuel needed to come back to earth on the surface of Mars, or the space entity being explored, making the overall mission more cost effective by enabling larger usable mass. The major disadvantage methane has over hydrogen is it provides a lower specific impulse, or lower rocket performance. The UTEP Center for Space Exploration and Technology Research (cSETR) in partnership with the National Aeronautics and Space Administration (NASA) has been the leading research center for the advancement of Liquid Oxygen (LOX) and Liquid Methane (LCH4) propulsion technologies. Through this partnership, the CROME engine, a throattable 500 lbf LOX/LCH4 rocket engine, was designed and developed. The engine will serve as the main propulsion system for Daedalus, a suborbital demonstration vehicle being developed by the cSETR. The purpose of Daedalus mission and the engine is to fire in space under microgravity conditions to demonstrate its restartability. This thesis details the design process, decisions, and characteristics of the engine to serve as a complete design guide.

  9. Dissolved methane oxidation and competition for oxygen in down-flow hanging sponge reactor for post-treatment of anaerobic wastewater treatment

    OpenAIRE

    Hatamoto, Masashi; Miyauchi, Tomo; Kindaichi, Tomonori; Ozaki, Noriatsu; Ohashi, Akiyoshi

    2011-01-01

    Post-treatment of anaerobic wastewater was undertaken to biologically oxidize dissolved methane, with the aim of preventing methane emission. The performance of dissolved methane oxidation and competition for oxygen among methane, ammonium, organic matter, and sulfide oxidizing bacteria were investigated using a lab-scale closed-type down-flow hanging sponge (OHS) reactor. Under the oxygen abundant condition of a hydraulic retention time of 2 h and volumetric air supply rate of 12.95 m(3)-air...

  10. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    Science.gov (United States)

    Mansell, J. Matthew; Abney, Morgan B.

    2012-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these oxygenated compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing.

  11. Theoretical Rocket Performance of Liquid Methane with Several Fluorine-Oxygen Mixtures Assuming Frozen Composition

    Science.gov (United States)

    Gordon, Sanford; Kastner, Michael E

    1958-01-01

    Theoretical rocket performance for frozen composition during expansion was calculated for liquid methane with several fluorine-oxygen mixtures for a range of pressure ratios and oxidant-fuel ratios. The parameters included are specific impulse, combustion-chamber temperature, nozzle-exit temperature molecular weight, characteristic velocity, coefficient of thrust, ratio of nozzle-exit area to throat area, specific heat at constant pressure, isentropic exponent, viscosity, and thermal conductivity. The maximum calculated value of specific impulse for a chamber pressure of 600 pounds per square inch absolute (40.827atm) and an exit pressure of 1 atmosphere is 315.3 for 79.67 percent fluorine in the oxidant.

  12. Methane Post-Processor Development to Increase Oxygen Recovery beyond State-of-the-Art Carbon Dioxide Reduction Technology

    Science.gov (United States)

    Abney, Morgan B.; Greenwood, Zachary; Miller, Lee A.; Alvarez, Giraldo; Iannantuono, Michelle; Jones, Kenny

    2013-01-01

    State-of-the-art life support carbon dioxide (CO2) reduction technology, based on the Sabatier reaction, is theoretically capable of 50% recovery of oxygen from metabolic CO2. This recovery is constrained by the limited availability of reactant hydrogen. Post-processing of the methane byproduct from the Sabatier reactor results in hydrogen recycle and a subsequent increase in oxygen recovery. For this purpose, a Methane Post-Processor Assembly containing three sub-systems has been developed and tested. The assembly includes a Methane Purification Assembly (MePA) to remove residual CO2 and water vapor from the Sabatier product stream, a Plasma Pyrolysis Assembly (PPA) to partially pyrolyze methane into hydrogen and acetylene, and an Acetylene Separation Assembly (ASepA) to purify the hydrogen product for recycle. The results of partially integrated testing of the sub-systems are reported

  13. Numerical modelling of continuous spin detonation in rich methane-oxygen mixture

    International Nuclear Information System (INIS)

    Trotsyuk, A V

    2016-01-01

    A numerical simulation of a two-dimensional structure of the detonation wave (DW) in a rich (equivalence ratio φ=1.5) methane-air mixture at normal initial condition has been conducted. The computations have been performed in a wide range of channel heights. From the analysis of the flow structure and the number of primary transverse waves in the channel, the dominant size of the detonation cell for studied mixture has been determined to be 45÷50 cm. Based on the fundamental studies of multi-front (cellular) structure of the classical propagating DW in methane mixtures, numerical simulation of continuous spin detonation (CSD) of rich (φ=1.2) methane-oxygen mixture has been carried out in the cylindrical detonation chamber (DC) of the rocket-type engine. We studied the global flow structure in DC, and the detailed structure of the front of the rotating DW. Integral characteristics of the detonation process - the distribution of average values of static and total pressure along the length of the DC, and the value of specific impulse have been obtained. The geometric limit of stable existence of CSD has been determined. (paper)

  14. Final Report: Room Temperature Electrochemical Upgrading of Methane to Oxygenate Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Mustain, William

    2018-01-02

    The overall objective of this project is to discover the nature of the electrochemically active sites and to uncover the mechanisms for the electrocatalytic transformation of small organic molecules to oxygenate products such as methanol, formaldehyde, carbon monoxide and acetylene. Among the feedstocks of interest in this study are: methane, carbon dioxide, and acetic acid. Methane is an incredibly attractive potential feedstock because of the recent discovery of large shale deposits; carbon dioxide is potentially a very available feedstock from carbon capture technologies; acetic acid (as well as CH4 and CO2 and ethanol) has potential as a bio-derived feedstock. This report summarizes the major results to date regarding the electrochemical transformation of CH4, CO2 and acetic acid to chemicals and fuels – with a primary focus on methane. Finer details are available in each of the projects annual reports. In addition to the primary objective, the work in this project has led to synergistic discoveries that are advantageous to other fields including: catalyst layer deposition, anion exchange membrane fuel cells, CO2 capture and li-ion batteries. Those are very briefly discussed as well.

  15. Electron loss and capture from low-charge-state oxygen projectiles in methane

    International Nuclear Information System (INIS)

    Santos, A C F; Wolff, W; Sant’Anna, M M; Sigaud, G M; DuBois, R D

    2013-01-01

    Absolute cross sections for single- and double-electron loss and single- and multiple-electron capture of 15–1000 keV oxygen projectiles (q = −1, 0, 1, 2) colliding with the methane molecule are presented. The experimental data are used to examine cross-section scaling characteristics for the electron loss of various projectiles. In addition, a modified version of the free-collision model was employed for the calculation of the single- and total-electron-loss cross sections of oxygen projectiles presented in this work. The comparison of the calculated cross sections with the present experimental data shows very good agreement for projectile velocities above 1.0 au. The comparison of the present single-electron-capture cross sections with other projectiles having the same charge shows good agreement, and a common curve can be drawn through the different data sets. (paper)

  16. Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad B. S.

    2017-01-01

    Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.

  17. Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad

    2016-08-22

    Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.

  18. Air-adapted Methanosarcina acetivorans shows high methane production and develops resistance against oxygen stress.

    Directory of Open Access Journals (Sweden)

    Ricardo Jasso-Chávez

    Full Text Available Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells. In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii the thiol-molecules (cysteine + coenzyme M-SH + sulfide and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.

  19. Effects of zilpaterol hydrochloride on methane production, total body oxygen consumption, and blood metabolites in finishing beef steers

    Science.gov (United States)

    An indirect calorimetry experiment was conducted to determine the effects of feeding zilpaterol hydrochloride (ZH) for 20 d on total body oxygen consumption, respiratory quotient, methane production, and blood metabolites in finishing beef steers. Sixteen Angus steers (initial BW = 555 ± 12.7 kg) w...

  20. Thermodynamic analysis of direct internal reforming of methane and butane in proton and oxygen conducting fuel cells

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Geerlings, J.J.C.

    2008-01-01

    We present results of a thermodynamic analysis of direct internal reforming fuel cells, based on either a proton conducting fuel cell (FC-H+) or an oxygen ion conducting fuel cell (FC-O2-). We analyze the option of methane as fuel as well as butane. The model self-consistently combines all chemical

  1. Dissolved methane oxidation and competition for oxygen in down-flow hanging sponge reactor for post-treatment of anaerobic wastewater treatment.

    Science.gov (United States)

    Hatamoto, Masashi; Miyauchi, Tomo; Kindaichi, Tomonori; Ozaki, Noriatsu; Ohashi, Akiyoshi

    2011-11-01

    Post-treatment of anaerobic wastewater was undertaken to biologically oxidize dissolved methane, with the aim of preventing methane emission. The performance of dissolved methane oxidation and competition for oxygen among methane, ammonium, organic matter, and sulfide oxidizing bacteria were investigated using a lab-scale closed-type down-flow hanging sponge (DHS) reactor. Under the oxygen abundant condition of a hydraulic retention time of 2h and volumetric air supply rate of 12.95m(3)-airm(-3)day(-1), greater than 90% oxidation of dissolved methane, ammonium, sulfide, and organic matter was achieved. With reduction in the air supply rate, ammonium oxidation first ceased, after which methane oxidation deteriorated. Sulfide oxidation was disrupted in the final step, indicating that COD and sulfide oxidation occurred prior to methane oxidation. A microbial community analysis revealed that peculiar methanotrophic communities dominating the Methylocaldum species were formed in the DHS reactor operation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Krypton Ion Thruster Performance

    Science.gov (United States)

    Patterson, Michael J.; Williams, George J.

    1992-01-01

    Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4 to 5.5 kW. The data presented are compared and contrasted to the data obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust to power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order of magnitude power throttling was demonstrated using a simplified power-throttling strategy.

  3. Technical Note: Calibration device for the krypton hygrometer KH20

    Directory of Open Access Journals (Sweden)

    T. Foken

    2012-08-01

    Full Text Available A calibration device for krypton hygrometers (KH20, Campbell Scientific, Inc. with variable path length is presented. This unit allows for in-situ calibrations of the krypton hygrometer, which is typically not very stable over time, during measuring campaigns. It was constructed mainly for application at high altitudes and low temperatures, where further improvements are needed to the IR-hygrometers which are normally used. The changing path length requires that a changing concentration of the absorber be simulated. Because oxygen absorbs more strongly than water vapour, the calibration is made against oxygen and transferred to water vapour. The design of the calibration instrument is made as one unit containing a stepper motor system, PC and humidity sensor. For the calibration, it is necessary to install the krypton hygrometer on this unit.

  4. Krypton for computed tomography lung ventilation imaging: preliminary animal data.

    Science.gov (United States)

    Mahnken, Andreas H; Jost, Gregor; Pietsch, Hubertus

    2015-05-01

    The objective of this study was to assess the feasibility and safety of krypton ventilation imaging with intraindividual comparison to xenon ventilation computed tomography (CT). In a first step, attenuation of different concentrations of xenon and krypton was analyzed in a phantom setting. Thereafter, 7 male New Zealand white rabbits (4.4-6.0 kg) were included in an animal study. After orotracheal intubation, an unenhanced CT scan was obtained in end-inspiratory breath-hold. Thereafter, xenon- (30%) and krypton-enhanced (70%) ventilation CT was performed in random order. After a 2-minute wash-in of gas A, CT imaging was performed. After a 45-minute wash-out period and another 2-minute wash-in of gas B, another CT scan was performed using the same scan protocol. Heart rate and oxygen saturation were measured. Unenhanced and krypton or xenon data were registered and subtracted using a nonrigid image registration tool. Enhancement was quantified and statistically analyzed. One animal had to be excluded from data analysis owing to problems during intubation. The CT scans in the remaining 6 animals were completed without complications. There were no relevant differences in oxygen saturation or heart rate between the scans. Xenon resulted in a mean increase of enhancement of 35.3 ± 5.5 HU, whereas krypton achieved a mean increase of 21.9 ± 1.8 HU in enhancement (P = 0.0055). The use of krypton for lung ventilation imaging appears to be feasible and safe. Despite the use of a markedly higher concentration of krypton, enhancement is significantly worse when compared with xenon CT ventilation imaging, but sufficiently high for CT ventilation imaging studies.

  5. Combustion Stability Characteristics of the Project Morpheus Liquid Oxygen / Liquid Methane Main Engine

    Science.gov (United States)

    Melcher, John C.; Morehead, Robert L.

    2014-01-01

    The project Morpheus liquid oxygen (LOX) / liquid methane (LCH4) main engine is a Johnson Space Center (JSC) designed 5,000 lbf-thrust, 4:1 throttling, pressure-fed cryogenic engine using an impinging element injector design. The engine met or exceeded all performance requirements without experiencing any in- ight failures, but the engine exhibited acoustic-coupled combustion instabilities during sea-level ground-based testing. First tangential (1T), rst radial (1R), 1T1R, and higher order modes were triggered by conditions during the Morpheus vehicle derived low chamber pressure startup sequence. The instability was never observed to initiate during mainstage, even at low power levels. Ground-interaction acoustics aggravated the instability in vehicle tests. Analysis of more than 200 hot re tests on the Morpheus vehicle and Stennis Space Center (SSC) test stand showed a relationship between ignition stability and injector/chamber pressure. The instability had the distinct characteristic of initiating at high relative injection pressure drop at low chamber pressure during the start sequence. Data analysis suggests that the two-phase density during engine start results in a high injection velocity, possibly triggering the instabilities predicted by the Hewitt stability curves. Engine ignition instability was successfully mitigated via a higher-chamber pressure start sequence (e.g., 50% power level vs 30%) and operational propellant start temperature limits that maintained \\cold LOX" and \\warm methane" at the engine inlet. The main engine successfully demonstrated 4:1 throttling without chugging during mainstage, but chug instabilities were observed during some engine shutdown sequences at low injector pressure drop, especially during vehicle landing.

  6. Method for separating krypton isotopes

    International Nuclear Information System (INIS)

    Porter, J.T.

    1980-01-01

    Methods and apparatus for separating krypton isotopes utilizing low temperature selective infrared excitation of 85krypton difluoride in an isotopic compound mixture. Multiphoton ir excitation and uv excitation techniques are used, as well as cryogenic matrix isolation and inert buffer gas isolation techniques

  7. Solid sources of krypton-85

    International Nuclear Information System (INIS)

    Puig, J.R.; Sandier, J.

    1962-01-01

    Krypton-85, a β-emitter with a long half-life and low biological hazard, has considerable industrial potentialities. It is difficult, however, to manufacture sources since the element occurs in gaseous form and cannot be chemically fixed. The authors describe a method of krypton-fixation in a macromolecular matrix formed by mass polymerization of a liquid monomer containing krypton; they also give an account of the preparation of two types of source produced in this way-one enclosed in polystyrene, the other in polyvinyl acetate. Such sources lose krypton; the activity of the first decreases by 8 % daily, that of the second by 3 % daily. These apparent decays enable the diffusion coefficients of krypton in these polymers to be calculated. Diffusion appears to be prevented by the cross-linkages which exist in the polymers. (author) [fr

  8. Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

    Directory of Open Access Journals (Sweden)

    Yuni Krisyuningsih Krisnandi

    2015-11-01

    Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

  9. Krypton-enhanced ventilation CT with dual energy technique: experimental study for optimal krypton concentration.

    Science.gov (United States)

    Chung, Yong Eun; Hong, Sae Rom; Lee, Mi-Jung; Lee, Myungsu; Lee, Hye-Jeong

    2014-11-01

    To assess the feasibility of krypton-enhanced ventilation CT using dual energy (DE) technique for various krypton concentrations and to determine the appropriate krypton concentration for DE ventilation CT through an animal study. Baseline DECT was first performed on seven New Zealand white rabbits. The animals were then ventilated using 20%, 30%, 40%, 50%, 60%, to 70% krypton concentration, and DECT was performed for each concentration. Krypton extraction was performed through a workstation, and results were displayed on a color map. Overlay Hounsfield unit (HU) values were obtained by two observers in consensus readings. A linear mixed model was used to correlate overlay HU values and krypton concentrations. Visual assessments of the homogeneity of krypton maps were also performed. Mean overlay HU values according to krypton concentration were as follows; 20% krypton, 1.68 ± 5.15; 30% krypton, 3.73 ± 5.93; 40% krypton, 6.92 ± 5.51; 50% krypton, 10.88 ± 5.17; 60% krypton, 14.54 ± 4.23; and 70% krypton, 18.79 ± 3.63. We observed a significant correlation between overlay HU values on krypton maps and krypton concentrations (P krypton color maps, all observers determined universal enhancement on the 70% krypton map for all animals. It is feasible to evaluate lung ventilation function using DECT with a krypton concentration of at least 70%.

  10. Effect of oxygen atoms dissociated by non-equilibrium plasma on flame of methane oxygen and argon pre-mixture gas

    Science.gov (United States)

    Akashi, Haruaki; Yoshinaga, Tomokazu; Sasaki, Koichi

    2014-10-01

    For more efficient way of combustion, plasma-assisted combustion has been investigated by many researchers. But it is very difficult to clarify the effect of plasma even on the flame of methane. Because there are many complex chemical reactions in combustion system. Sasaki et al. has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power. They also measured emission from Second Positive Band System of nitrogen during the irradiation. The emission indicates existence of high energy electrons which are accelerated by the microwave. The high energy electrons also dissociate oxygen molecules easily and oxygen atom would have some effects on the flame. But the dissociation ratio of oxygen molecules by the non-equilibrium plasma is significantly low, compared to that in the combustion reaction. To clarify the effect of dissociated oxygen atoms on the flame, dependence of dissociation ratio of oxygen on the flame has been examined using CHEMKIN. It is found that in the case of low dissociation ratio of 10-6, the ignition of the flame becomes slightly earlier. It is also found that in the case of high dissociation ratio of 10-3, the ignition time becomes significantly earlier by almost half. This work was supported by KAKENHI (22340170).

  11. Flow Field Measurements of Methane-Oxygen Turbulent Nonpremixed Flames at High Pressure

    Science.gov (United States)

    Iino, Kimio; Kikkawa, Hoshitaka; Akamatsu, Fumiteru; Katsuki, Masashi

    We carried out the flow field measurement of methane-oxygen turbulent nonpremixed flame in non-combusting and combusting situations at high pressures using LDV. The main objectives are to study the influences of combustion on the turbulence structure at high pressures and to provide detailed data on which numerical predictions on such flows can rely. Direct observation and CH* chemiluminescence detection are conducted at high pressures up to 1.0MPa. It was found that the flame length at elevated pressures became constant. From flow field measurements, the following features of flames at elevated pressure were found: (1) the existence of flame suppressed turbulence in the upstream region of the jet and enhanced it in the downstream region with increasing pressure; (2) Turbulence in the flame was more anisotropic than in the corresponding cold jet in all regions of the flow with increasing pressure; (3) Reynolds shear stresses did not change at elevated pressure; (4) Combustion processes had a marked influence on the turbulence macroscale under high pressures, however, the turbulence macroscale was not changed even with the increase in pressure.

  12. Krypton-85 enrichment by adsorption-desorption process

    International Nuclear Information System (INIS)

    Khan, A.A.; Deshingkar, D.S.; Ramarathinam, K.

    1975-01-01

    The use of activated charcoal columns in conjunction with cryogenic distillation system for concentration of krypton-85 in fuel reprocessing process off-gas stream is reported. Dynamic adsorption of krypton on activated charcoals and its subsequent desorption by applying vacuum were studied. The possible reduction in the quantity of carrier gas to be liquified in the cryogenic system by utilising this process has been discussed on the basis of results of laboratory evaluations. The possibility of elimination of air and oxygen to avoid explosion hazards associated with radiolytic formation and concentration of ozone has also been considered. (author)

  13. Ce-Fe-O mixed oxide as oxygen carrier for the direct partial oxidation of methane to syngas

    Institute of Scientific and Technical Information of China (English)

    魏永刚; 王华; 李孔斋

    2010-01-01

    The Ce-Fe-O mixed oxide with a ratio of Ce/Fe=7:3, which was prepared by coprecipitation method and employed as oxygen carrier, for direct partial oxidation of methane to syngas in the absence of gaseous oxygen was explored. The mixed oxide was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the catalytic performances were studied in a fixed-bed quartz reactor and a thermogravimetric reactor, respectively. Approximately 99.4% H2 se...

  14. Development and assessment of a distribution network of hydro-methane, methanol, oxygen and carbon dioxide in Paraguay

    International Nuclear Information System (INIS)

    Rivarolo, M.; Marmi, S.; Riveros-Godoy, G.; Magistri, L.

    2014-01-01

    Highlights: • We investigate different transporting modes of hydro-methane, methanol, CO 2 and O 2 . • We determine the best transportation technology from an economic point of view. • The best pathway to distribute the hydro-methane depends on quantity and distance. • Methanol distribution presents the lowest cost delivery. - Abstract: This paper summarizes key results of the analysis of different transport modes of hydro-methane, methanol, carbon dioxide and oxygen in Paraguay, Brazil and Argentina. Hydro-methane is produced in Paraguay and can be used to fuel natural gas vehicles, substituting gasoline and diesel which are at the moment imported from foreign countries. Methanol, also produced in Paraguay, is delivered to Brazil, which is one of the Countries with the highest demand in the region. Oxygen can be sold to Argentina for medical and industrial use. Carbon dioxide is delivered throughout Paraguay. The aim of this study is to determine the best transportation technology from an economic and strategic point of view, minimizing costs associated to products distribution. Several scenarios are investigated; each scenario is associated with different delivery modes. A model is developed to estimate both capital and variable costs for different transportation technologies (pipeline, trucks, ships) in order to choose the lowest-cost delivery mode for each product, depending on distances and flow rates. Four different analysis are performed for each scenario, varying the number of vehicles which must be fueled by hydro-methane and considering its influence on the results. The methodology presented here has a general value, thus it can be easily employed for the economic analysis of different fuels and distribution networks, also placed in different scenarios

  15. Novel CO2 Separation and Methanation for Oxygen and Fuel Production, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes a novel efficient, compact, and lightweight MicrolithREG-based CO2 separator and methanation reactor to separate CO2 from...

  16. Selective coke combustion by oxygen pulsing during Mo/ZSM‐5‐catalyzed methane dehydroaromatization

    NARCIS (Netherlands)

    Kosinov, N.; Coumans, F.J.A.G.; Uslamin, E.A.; Kapteijn, F.; Hensen, E.J.M.

    2016-01-01

    Non-oxidative methane dehydroaromatization is a promising reaction to directly convert natural gas into aromatic hydrocarbons and hydrogen. Commercialization of this technology is hampered by rapid catalyst deactivation because of coking. A novel approach is presented involving selective oxidation

  17. Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

    KAUST Repository

    Kim, Daesang

    2015-07-01

    Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane-oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH+O⇌HCO+ +E- and to the main CH consumption reaction CH+O2 ⇌O+HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ +E- →products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH-, and O-) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the

  18. Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

    KAUST Repository

    Kim, Daesang; Rizzi, Francesco; Cheng, Kwok Wah; Han, Jie; Bisetti, Fabrizio; Knio, Omar Mohamad

    2015-01-01

    Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane-oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH+O⇌HCO+ +E- and to the main CH consumption reaction CH+O2 ⇌O+HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ +E- →products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH-, and O-) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the

  19. De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts

    Directory of Open Access Journals (Sweden)

    R.Y. Raskar

    2012-06-01

    Full Text Available The de-oxygenation of CO2 was explored by using hydrogen, methane, carbon etc., over alumina supported catalysts. The alumina-supported ruthenium, rhodium, platinum, molybdenum, vanadium and magnesium catalysts were first reduced in hydrogen atmosphere and then used for the de-oxygenation of CO2. Furthermore, experimental variables for the de-oxygenation of CO2 were temperature (range 50 to 650 oC, H2/CO2 mole ratios (1.0 to 5, and catalyst loading (0.5 to 10 wt %. During the de-oxygenation of CO2 with H2 or CH4 or carbon, conversion of CO2, selectivity to CO and CH4 were estimated. Moreover, 25.4 % conversion of CO2 by hydrogen was observed over 1 wt% Pt/Al2O3 catalyst at 650 oC with 33.8 % selectivity to CH4. However, 8.1 to 13.9 % conversion of CO2 was observed over 1 wt% Pt/Al2O3 catalyst at 550 oC in the presence of both H2 and CH4. Moreover, 42.8 to 79.4 % CH4 was converted with 9 to 23.1 % selectivity to CO. It was observed that the de-oxygenation of CO2 by hydrogen, carbon and methane produced carbon, CO and CH4. © 2012 BCREC UNDIP. All rights reservedReceived: 6th February 2012; Revised: 23rd April 2012; Accepted: 24th April 2012[How to Cite: R. Y. Raskar, K. B. Kale, A. G. Gaikwad. (2011. De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 59-69.  doi:10.9767/bcrec.7.1.1631.59-69][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1631.59-69 ] | View in 

  20. Effect of substrate temperature on the structure of amorphous oxygenated hydrocarbon films grown with a pulsed supersonic methane plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Fedoseeva, Yu. V., E-mail: fedoseeva@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Pozdnyakov, G.A. [Khristianovich Institute of Theoretical and Applied Mechanics, SB RAS, Novosibirsk 630090 (Russian Federation); Okotrub, A.V.; Kanygin, M.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nastaushev, Yu. V. [Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Vilkov, O.Y. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Bulusheva, L.G. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2016-11-01

    Highlights: • A deposition of supersonic methane plasma flow on silicon substrate produces amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) film. • The thickness, composition, and wettability of the film depend on the substrate temperature. • A rise of the substrate temperature from 500 to 700 °C promotes the sp{sup 3}-hybridization carbon formation. - Abstract: Since amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) films are promising engineering materials a study of the structure and composition of the films depending on the conditions of synthesis is important for controlling of their physicochemical properties. Here, we used the methods of scanning and transmission electron microscopy, X-ray photoelectron, near-edge X-ray absorption fine structure, Fourier transform infrared and Raman spectroscopy to reveal changes in the chemical connectivity of CO{sub x}H{sub y} films grown on silicon substrates heated to 300, 500, and 700 °C using a supersonic flow of methane plasma. It was found that the CO{sub x}H{sub y} films, deposited at 300 and 500 °C, were mainly composed of the sp{sup 2}-hybridized carbon areas with various oxygen species. A rise of the substrate temperature caused an increase of the portion of tetrahedral carbon atoms as well as carboxyl and hydroxyl groups. With growth of the substrate temperature, the film thickness reduced monotonically from 400 to 180 nm, while the film adhesion improved substantially. The films, deposited at lower temperatures, showed high hydrophilicity due to porosity and presence of oxygenated groups both at the surface and in the bulk.

  1. Krypton retention on solid adsorbents

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.

    1981-08-01

    Over a dozen prospective adsorbents for krypton were studied and evaluated with respect to adsorption capacity and cost for dissolver off-gas streams from nuclear reprocessing plants. Results show that, at subambient temperature (-40 0 to -80 0 C), the commercially available hydrogen mordenite has sufficient adsorptive capacity to be the most cost-effective material studied. Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite. The results indicate that a solid adsorbent system is feasible and competitive with other developing systems whih utilize fluorocarbon absorption and cryogenic distillation

  2. Hydrogen Production from Cyclic Chemical Looping Steam Methane Reforming over Yttrium Promoted Ni/SBA-16 Oxygen Carrier

    Directory of Open Access Journals (Sweden)

    Sanaz Daneshmand-Jahromi

    2017-09-01

    Full Text Available In this work, the modification of Ni/SBA-16 oxygen carrier (OC with yttrium promoter is investigated. The yttrium promoted Ni-based oxygen carrier was synthesized via co-impregnation method and applied in chemical looping steam methane reforming (CL-SMR process, which is used for the production of clean energy carrier. The reaction temperature (500–750 °C, Y loading (2.5–7.4 wt. %, steam/carbon molar ratio (1–5, Ni loading (10–30 wt. % and life time of OCs over 16 cycles at 650 °C were studied to investigate and optimize the structure of OC and process temperature with maximizing average methane conversion and hydrogen production yield. The synthesized OCs were characterized by multiples techniques. The results of X-ray powder diffraction (XRD and energy dispersive X-ray spectroscopy (EDX of reacted OCs showed that the presence of Y particles on the surface of OCs reduces the coke formation. The smaller NiO species were found for the yttrium promoted OC and therefore the distribution of Ni particles was improved. The reduction-oxidation (redox results revealed that 25Ni-2.5Y/SBA-16 OC has the highest catalytic activity of about 99.83% average CH4 conversion and 85.34% H2 production yield at reduction temperature of 650 °C with the steam to carbon molar ratio of 2.

  3. An experimental study of the structure of laminar premixed flames of ethanol/methane/oxygen/argon

    Science.gov (United States)

    Tran, L.S.; Glaude, P.A.; Battin-Leclerc, F.

    2013-01-01

    The structures of three laminar premixed stoichiometric flames at low pressure (6.7 kPa): a pure methane flame, a pure ethanol flame and a methane flame doped by 30% of ethanol, have been investigated and compared. The results consist of concentration profiles of methane, ethanol, O2, Ar, CO, CO2, H2O, H2, C2H6, C2H4, C2H2, C3H8, C3H6, p-C3H4, a-C3H4, CH2O, CH3HCO, measured as a function of the height above the burner by probe sampling followed by on-line gas chromatography analyses. Flame temperature profiles have been also obtained using a PtRh (6%)-PtRh (30%) type B thermocouple. The similarities and differences between the three flames were analyzed. The results show that, in these three flames, the concentration of the C2 intermediates is much larger than that of the C3 species. In general, mole fraction of all intermediate species in the pure ethanol flame is the largest, followed by the doped flame, and finally the pure methane flame. PMID:24092946

  4. Experimental study of adiabatic cellular premixed flames of methane (ethane, propane) + oxygen + carbon dioxide mixtures

    NARCIS (Netherlands)

    Konnov, A.A.; Dyakov, I.V.

    2007-01-01

    Experimental studies of adiabatic cellular flames of CH4 + O2 + CO2, C2H6 + O2 + CO2, and C3H8 + O2 + CO2 are presented. Visual and photographic observations of the flames were performed to quantify their cellular structure. Non-stretched flames of methane and propane were stabilized at atmospheric

  5. Retention of krypton on polymethyl methacrylate

    International Nuclear Information System (INIS)

    Ciric, M.M.; Cvjeticanin, N.M.; Radak, B.B.

    1975-01-01

    Retention of krypton on polymethyl methacrylate was studied as a function of kryptonation pressure (P), temperature (T) and time (t). It was found that the dependence of the retained quantity on P, T, and t is in accordance with the diffusion theory. The optimum results (i.e., the maximum retained quantity and the best stability of the kryptonate) were obtained at elevated kryptonation temperatures (200 0 C). The diffusion coefficients of krypton in polymethyl methacrylate, determined from the dekryptonation process, vary from 1 x 10 -10 cm 2 /s to 0.2 x 10 -10 cm 2 /s for samples kryptonated at 20 0 C and 200 0 C respectively. The results have been discussed from the viewpoint of radiation and thermal stability of kryptonated polymethyl methacrylate. Inadequate radiation stability could be the main obstacle for practical purposes. (U.S.)

  6. Krypton retention on solid adsorbents

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.

    1980-01-01

    Radioactive krypton-85 is released to the atmosphere in the off-gas from nuclear reprocessing plants. Three main methods have been suggested for removal of krypton from off-gas streams: cryogenic distillation; fluorocarbon absorption; and adsorption on solid sorbents. Use of solid adsorbents is the least developed of these methods, but offers the potential advantages of enhanced safety and lower operating costs. An experimental laboratory program was developed that will be used to investigate systematically many solid adsorbents (such as zeolites, i.e., mordenites) for trapping krypton in air. The objective of this investigation is to find an adsorbent that is more economical than silver-exchanged mordenite. Various physical and chemical characteristics such as adsorption isotherms, decontamination factors, co-adsorption, regeneration, and the mechanism and kinetics of noble gas adsorption were used to characterize the adsorbents. In the experimental program, a gas chromatograph using a helium ionization detector was used to measure the krypton in air before and after the adsorbent bed. This method can determine directly decontamination factors greater than 100

  7. Testing of a Liquid Oxygen/Liquid Methane Reaction Control Thruster in a New Altitude Rocket Engine Test Facility

    Science.gov (United States)

    Meyer, Michael L.; Arrington, Lynn A.; Kleinhenz, Julie E.; Marshall, William M.

    2012-01-01

    A relocated rocket engine test facility, the Altitude Combustion Stand (ACS), was activated in 2009 at the NASA Glenn Research Center. This facility has the capability to test with a variety of propellants and up to a thrust level of 2000 lbf (8.9 kN) with precise measurement of propellant conditions, propellant flow rates, thrust and altitude conditions. These measurements enable accurate determination of a thruster and/or nozzle s altitude performance for both technology development and flight qualification purposes. In addition the facility was designed to enable efficient test operations to control costs for technology and advanced development projects. A liquid oxygen-liquid methane technology development test program was conducted in the ACS from the fall of 2009 to the fall of 2010. Three test phases were conducted investigating different operational modes and in addition, the project required the complexity of controlling propellant inlet temperatures over an extremely wide range. Despite the challenges of a unique propellant (liquid methane) and wide operating conditions, the facility performed well and delivered up to 24 hot fire tests in a single test day. The resulting data validated the feasibility of utilizing this propellant combination for future deep space applications.

  8. Bonding xenon and krypton on the surface of uranium dioxide single crystal

    Directory of Open Access Journals (Sweden)

    Dąbrowski Ludwik

    2014-08-01

    Full Text Available We present density functional theory (DFT calculation results of krypton and xenon atoms interaction on the surface of uranium dioxide single crystal. A pseudo-potential approach in the generalised gradient approximation (GGA was applied using the ABINIT program package. To compute the unit cell parameters, the 25 atom super-cell was chosen. It has been revealed that close to the surface of a potential well is formed for xenon and krypton atom due to its interaction with the atoms of oxygen and uranium. Depth and shape of the well is the subject of ab initio calculations in adiabatic approximation. The calculations were performed both for the case of oxygenic and metallic surfaces. It has been shown that the potential well for the oxygenic surface is deeper than for the metallic surface. The thermal stability of immobilising the atoms of krypton and xenon in the potential wells were evaluated. The results are shown in graphs.

  9. Development and Integration of the Janus Robotic Lander: A Liquid Oxygen-Liquid Methane Propulsion System Testbed

    Science.gov (United States)

    Ponce, Raul

    Initiatives have emerged with the goal of sending humans to other places in our solar system. New technologies are being developed that will allow for more efficient space systems to transport future astronauts. One of those technologies is the implementation of propulsion systems that use liquid oxygen and liquid methane (LO2-LCH4) as propellants. The benefits of a LO2-LCH4 propulsion system are plenty. One of the main advantages is the possibility of manufacturing the propellants at the destination body. A space vehicle which relies solely on liquid oxygen and liquid methane for its main propulsion and reaction control engines is necessary to exploit this advantage. At the University of Texas at El Paso (UTEP) MIRO Center for Space Exploration Technology Research (cSETR) such a vehicle is being developed. Janus is a robotic lander vehicle with the capability of vertical take-off and landing (VTOL) which integrates several LO2-LCH 4 systems that are being devised in-house. The vehicle will serve as a testbed for the parallel operation of these propulsion systems while being fed from common propellant tanks. The following work describes the efforts done at the cSETR to develop the first prototype of the vehicle as well as the plan to move forward in the design of the subsequent prototypes that will lead to a flight vehicle. In order to ensure an eventual smooth integration of the different subsystems that will form part of Janus, requirements were defined for each individual subsystem as well as the vehicle as a whole. Preliminary testing procedures and layouts have also been developed and will be discussed to detail in this text. Furthermore, the current endeavors in the design of each subsystem and the way that they interact with one another within the lander will be explained.

  10. Numerical Study of the Working Process in the Reducing Gas Generator of the Upper Stage Oxygen - Methane Engine

    Directory of Open Access Journals (Sweden)

    D. M. Yagodnikov

    2015-01-01

    Full Text Available This article deals with the problems of creating a reducing gas generator of the liquid rocket engine (LRE of upper stage using advanced fuel components, namely oxygen + liquid natural gas. Relevance of the work is justified by the need to create and develop of environmentally friendly missile systems for space applications using methane-based fuel (liquid natural gas. As compared to the currently used unsymmetrical dimethyl-hydrazine and kerosene, this fuel is environmentally safe, passive to corrosion, has better cooling properties and high energy characteristics in the re-generatively cooled chambers, as well as is advantageous for LRE of multiple start and use.The purpose of this work is a mathematical modeling, calculation of the working process efficiency, as well as study of gas-dynamic structure of the flow in the gas generator flow path. The object of study is the upper stage LRE gas generator, which uses the reducing scheme on the liquid propellants: oxygen + liquid methane. Research methods are based on numerical simulation.Computational studies allowed us to receive the velocity, temperatures, and concentrations of reactants and combustion products in the longitudinal section of gas generator. Analysis of the gas-dynamic structure of flow shows a complete equalization of the velocity field by 2/3 of the gas generator length. Thus, the same distance is not enough to equalize the temperature distribution of the gasification products and their concentrations in radius. Increasing the total excess oxidant ratio from 0.15 to 0.25 leads to a greater spread of the parameters at the exit of the gas generator by ~ 13 ÷ 17%. As a recommendation to reduce the size of the working area, is proposed a dual-zone gas generator-mixing scheme with fuel separately supplied to the first and second zones.

  11. Design documentation: Krypton encapsulation preconceptual design

    International Nuclear Information System (INIS)

    Knecht, D.A.

    1994-10-01

    US EPA regulations limit the release of Krypton-85 to the environment from commercial facilities after January 1, 1983. In order to comply with these regulations, Krypton-85, which would be released during reprocessing of commercial nuclear fuel, must be collected and stored. Technology currently exists for separation of krypton from other inert gases, and for its storage as a compressed gas in steel cylinders. The requirements, which would be imposed for 100-year storage of Krypton-85, have led to development of processes for encapsulation of krypton within a stable solid matrix. The objective of this effort was to provide preconceptual engineering designs, technical evaluations, and life cycle costing data for comparison of two alternate candidate processes for encapsulation of Krypton-85. This report has been prepared by The Ralph M. Parsons Company for the US Department of Energy

  12. Design documentation: Krypton encapsulation preconceptual design

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, D.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1994-10-01

    US EPA regulations limit the release of Krypton-85 to the environment from commercial facilities after January 1, 1983. In order to comply with these regulations, Krypton-85, which would be released during reprocessing of commercial nuclear fuel, must be collected and stored. Technology currently exists for separation of krypton from other inert gases, and for its storage as a compressed gas in steel cylinders. The requirements, which would be imposed for 100-year storage of Krypton-85, have led to development of processes for encapsulation of krypton within a stable solid matrix. The objective of this effort was to provide preconceptual engineering designs, technical evaluations, and life cycle costing data for comparison of two alternate candidate processes for encapsulation of Krypton-85. This report has been prepared by The Ralph M. Parsons Company for the US Department of Energy.

  13. Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2016-01-01

    chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

  14. Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad B. S.; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2017-01-01

    chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

  15. Immobilization technology for krypton in amorphous zeolite

    International Nuclear Information System (INIS)

    Takusagawa, Atsushi; Ishiyama, Keiichi

    1989-01-01

    Radioactive krypton recovered from the offgas of a reprocessing plant requires long-term storage on the order of 100 years. Immobilization technology for krypton into amorphous zeolite 5A is considered one of the best methods for long-term storage. In this report, conditions for immobilization treatment and stability of amorphous zeolite 5A loaded krypton against heat, radiation and water are discussed, and a treatment system using this technology is described. (author)

  16. Krypton retention on solid adsorbents

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.

    1982-01-01

    An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-40 0 to -80 0 C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite

  17. Long-term storage of recovered krypton

    International Nuclear Information System (INIS)

    Horii, Yuji; Yamamoto, Yoshimasa

    1983-01-01

    Various storage methods for krypton-85 recovered from a nuclear fuel reprocessing plant are under development in many countries. These methods include:(1) direct storage in pressurized cylinders, (2) storage of krypton adsorbed on charcoal or zeolite in pressurized cylinders and (3) immobilization (encapsulation) in zeolite. A krypton storage facility using pressurized cylinders has been constructed in the krypton recovery pilot plant in Tokaimura and other methods are now under development. These three methods are evaluated and the features of the constructed facility are also reported. (author)

  18. Separation, storage and disposal of krypton-85

    International Nuclear Information System (INIS)

    1980-01-01

    Technical means available for the retention of 85 Kr and its immobilization, storage and disposal are reviewed. Cryogenic processes for the separation of krypton and xenon from diluting gases are discussed in more detail. Besides the cryogenic processes, a liquid adsorption process for reprocessing off-gases and charcoal adsorption and membrane processes for reactor off-gases are also dealt with. The retained krypton can be stored in pressurized containers with air or water cooling. The containers can be kept in engineered storage facilities for an intermediate period or until the 85 Kr has decayed. Alternatively, the krypton may be encapsulated in a solid. The injection of gases containing krypton into suitable geologic strata may also be possible. Much of the equipment required for the separation and storage of krypton, well known from ordinary technology, often needs some adaptation. Further R and D work is, however, needed to solve some problems which are specific to highly concentrated fission krypton. The subject is reviewed under the following headings: methods available for the separation of krypton from off-gases; separation of krypton from reactor off-gas; separation of krypton from reprocessing off-gas; conditioning methods; engineering storage; transportation; disposal

  19. An improved potential for krypton

    International Nuclear Information System (INIS)

    Aziz, R.A.

    1979-01-01

    An improved potential for krypton is presented. It has the simple but realistic form used by Aziz and Chen for argon based on the HFD potential suggested by Ahlrichs et.al. The potential, with known long-range behaviour, was fitted to second virial, viscosity and thermal conductivity data. The potential appears to have the best overall predictive ability for dilute gas, bulk and microscopic data. (author)

  20. Methane emission and oxygen consumption in the hydroelectric dam of Petit Saut in French Guyana

    International Nuclear Information System (INIS)

    Galy-Lacaux, C.; Jambert, C.; Delmas, R.; Dumestre, J.F.; Labroue, L.; Cerdan, P.; Richard, S.

    1996-01-01

    Methane emissions from the hydroelectric dam of Petit-Saut, in French Guyana, were measured over a 20-months period. Since the beginning of the reservoir filling (January 1994), 300 km 2 of tropical forest have been submerged. Biological CH 4 oxidation, in the surface water of the lake and in the river downstream of the dam, lead to an intense 0 2 consumption. Emissions of CH 4 by diffusion into the atmosphere or by degassing of the water released into the river as well as the stock of dissolved gas in the lake, and their temporal dynamics, were studied. Maximum emissions of 700 t (CH 4 ) per day were attained in February 1994, corresponding to maximum dissolved CH 4 concentrations of 14 mg l -1 in the water column. Total emissions since January 1994, were calculated from the whole data set. (authors). 7 refs., 2 figs., 1 tab

  1. Atmospheric krypton-85 during 1962 and 1963

    Energy Technology Data Exchange (ETDEWEB)

    Ehhalt, D.; Muennich, K. O.; Roether, W.; Schoelch, J.; Stich, W.

    1963-11-15

    The krypton-85 found in the atmosphere presumably originates from two different sources, namely fission bomb tests and processing of burned-out fuel elements from nuclear reactors. This paper discusses the impact of the sources of krypton in the atmosphere in greater detail.

  2. 气相色谱质谱联用法测定液氧中微量的氪和氙%Determination of trace krypton and xenon in liquid oxygen by Gas Chromatography/Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    唐轩; 陈鹰; 吴建军

    2013-01-01

    Trace krypton and xenon was determined by gas chromatography/mass spectrometry with selection ion monitoring mode (SIM). The ions m/z=84 and m/z=132 were chosen as quantitative ion for krypton and xenon respectively. The results show that it is a simple way to implement, rapid detection and good selectivity. The linear relation between the peak area and concentration was excellent within the range of (1.0~100)×10-6 V/V. Meanwhile, the minimum detectable concentration and repeatability was also detected.%利用气相色谱质谱联用技术中的选择离子监测(SIM)方式对液氧中的微量氪气和氙气进行了测定。选择m/z为84的离子作为氪的定量离子、m/z为132的离子作为氙的定量离子。方法简单、快速、选择性好,在浓度为(1.0~100)×10-6 V/V范围内,峰面积与浓度有良好的线性关系。同时考察了方法的最低检测浓度和重复性。

  3. Iridotomy with red krypton laser.

    Science.gov (United States)

    Yassur, Y; David, R; Rosenblatt, I; Marmour, U

    1986-01-01

    Iridotomy with red krypton laser instead of blue-green argon laser was performed on 68 eyes with various types of angle-closure glaucoma. Patent iridotomy was obtained in all the eyes, mostly in one working session. In eight eyes secondary closure by pigment needed reopening with a few applications at the iridotomy site. There were no immediate or late complications of importance, the main advantage of the technique being the avoidance of the corneal epithelial and endothelial burns which commonly occur during argon laser iridotomy, particularly when the anterior chamber is shallow. PMID:3964628

  4. Impacts of a massive release of methane and hydrogen sulfide on oxygen and ozone during the late Permian mass extinction

    Science.gov (United States)

    Kaiho, Kunio; Koga, Seizi

    2013-08-01

    The largest mass extinction of animals and plants in both the ocean and on land occurred in the late Permian (252 Ma), largely coinciding with the largest flood basalt volcanism event in Siberia and an oceanic anoxic/euxinic event. We investigated the impacts of a massive release of methane (CH4) from the Siberian igneous province and the ocean and/or hydrogen sulfide (H2S) from the euxinic ocean on oxygen and ozone using photochemical model calculations. Our calculations indicated that an approximate of 14% decrease in atmospheric O2 levels would have occurred in the case of a large combined CH4 and H2S flux to the atmosphere, whereas an approximate of 8 to 10% decrease would have occurred from the CH4 flux and oxidation of all H2S in the ocean. The slight decrease in atmospheric O2 levels may have contributed to the extinction event. We demonstrate for the first time that a massive release of CH4 from the Siberian igneous province and a coincident massive release of CH4 and H2S did not cause ozone collapse. A collapse of stratospheric ozone leading to an increase in UV is not supported by the maximum model input levels for CH4 and H2S. These conclusions on O2 and O3 are correspondent to every H2S release percentages from the ocean to the atmosphere.

  5. The mathematical model structural-parametric synthesis of working processes in an oxygen-methane steam generator with flow swirl

    Science.gov (United States)

    Timoshinova, T. S.; Shmatov, D. P.; Kretinin, A. V.; Drozdov, I. G.

    2017-11-01

    While formulating a mathematical model of the flow and interaction between oxygen-methane fuel combustion products with tangentially swirled ballast water injected in the end of the combustion chamber in CAE product Fluent, which integrated into the ANSYS Workbench platform, the problem of structural-parametric synthesis is solved for structure optimization of the model. Equations are selected from the catalogue of Fluent physical models. Also optimization helps to find “regime” model parameters that determine the specific implementation of the model inside the synthesized structure. As a result, such solutions which were developed during creation of a numerical algorithm, as the choice of a turbulence model and the state equation, the methods for determining the thermodynamic thermophysical characteristics of combustion products, the choice of the radiation model, the choice of the resistance law for drops, the choice of the expression which allows to evaluate swirling flows lateral force, determination of the turbulent dispersion strength, choice of the mass exchange law, etc. Fields of temperature, pressure, velocity and volume fraction of phases were obtained at different ballast water mass flows. Dependence of wall temperature from mass flow of ballast water is constructed, that allows us to compare results of the experiment and mathematical modeling.

  6. Ultra-Trace Analysis of Krypton-85

    International Nuclear Information System (INIS)

    Daerr, H.; Kalinowski, M.; Kohler, M.; Sahling, P.

    2010-01-01

    To strengthen the efficiency and effectiveness of nuclear safeguards for detecting undeclared nuclear material and activities we propose to use the radioactive krypton isotope Krypton-85 as a tracer for clandestine plutonium production. The main idea is to detect inexplicable atmospheric Kr85 concentration using the novel technology atom trap trace analysis (ATTA) in order to detect an undeclared reprocessing facility. The Additional Protocol (INFCIRC/540, 1997) establishes the possibility to take environmental samples. Krypton-85 has a combination of unique features which makes it an ideal tracer for plutonium separation activities anywhere in the world. It is always generated along with plutonium and 99.9% remains within the fuel cladding. Due to its half-life of 10.76 years, significant amounts of krypton-85 still remain in the spent fuel even after long cooling times. Krypton is not removed from the atmosphere by any processes like chemical reactions or wash-out. Furthermore, there are no other relevant sources of krypton-85 besides of reprocessing. The novel technology of atom trap trace analysis (ATTA) has been demonstrated by the physics group at Argonne National Laboratory in 1999. This is an ultra-sensitive trace analysis technique able to detect single krypton atoms. We are setting up an ATTA apparatus in our laboratory, which is designed to fulfill all requirements to detect clandestine plutonium production. Our goal is to determine Krypton-85 concentration of one liter samples of atmospheric air with an analysis time of 3 hours. This sample volume reduction is a significant step, since one liter can be taken as a grab sample by sucking it directly into pre-evacuated bottles at atmospheric pressure. The small samples size and the short analysis time of ATTA will make it possible to use krypton-85 as a tracer for clandestine plutonium production with routine operation. (author)

  7. Soot Formation in Laminar Premixed Methane/Oxygen Flames at Atmospheric Pressure

    Science.gov (United States)

    Xu, F.; Lin, K.-C.; Faeth, G. M.

    1998-01-01

    Flame structure and soot formation were studied within soot-containing laminar premixed mc1hane/oxygen flames at atmospheric pressure. The following measurements were made: soot volume fractions by laser extinction, soot temperatures by multiline emission, gas temperatures (where soot was absent) by corrected fine-wire thermocouples, soot structure by thermophoretic sampling and transmission electron microscope (TEM), major gas species concentrations by sampling and gas chromatography, and gas velocities by laser velocimetry. Present measurements of gas species concentrations were in reasonably good agreement with earlier measurements due to Ramer et al. as well as predictions based on the detailed mechanisms of Frenklach and co-workers and Leung and Lindstedt: the predictions also suggest that H atom concentrations are in local thermodynamic equilibrium throughout the soot formation region. Using this information, it was found that measured soot surface growth rates could be correlated successfully by predictions based on the hydrogen-abstraction/carbon-addition (HACA) mechanisms of both Frenklach and co-workers and Colket and Hall, extending an earlier assessment of these mechanisms for premixed ethylene/air flames to conditions having larger H/C ratios and acetylene concentrations. Measured primary soot particle nucleation rates were somewhat lower than the earlier observations for laminar premixed ethylene/air flames and were significantly lower than corresponding rates in laminar diffusion flames. for reasons that still must be explained.

  8. Krypton based adsorption type cryogenic refrigerator

    Science.gov (United States)

    Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

    1989-01-01

    Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

  9. Krypton-85 pollution and atmospheric electricity

    International Nuclear Information System (INIS)

    Harrison, R.G.; ApSimon, H.M.

    1994-01-01

    Krypton-86 is a chemically inert radioactive gas present in the atmosphere, concentrations of which have been greatly increased by nuclear reprocessing and weapons testing since 1945. The long half-life (10.7 yr), allows the gas to mix thoroughly in the atmosphere. Ionization caused by krypton-85 increases the electrical conductivity of atmospheric air. Further increases in krypton-85 emissions seem inevitable. The increase in air conductivity due to release of krypton-85 will vary with height, and be larger over the oceans than over the land. Increases in conductivity will produce uncertain effects on atmospheric phenomena, so changes are compared in magnitude with other factors perturbing the conductivity, such as combustion aerosol burdens, volcanic eruptions and nuclear weapons testing. Conductivity changes are expected to have the greatest significance for meteorological phenomena close to the source. (Author)

  10. Coil-On-Plug Ignition for Oxygen/Methane Liquid Rocket Engines in Thermal-Vacuum Environments

    Science.gov (United States)

    Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

    2017-01-01

    A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX)/liquid methane (LCH4) rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/LCH4 propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. A coil-on-plug ignition system has been developed to successfully demonstrate ignition reliability at these conditions while preventing corona discharge issues. The ICPTA uses spark plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp -2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, hot-fire testing at Plum Brook demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/LCH4 propulsion systems in future spacecraft.

  11. Liquid Krypton Calorimeter Calibration Software

    CERN Document Server

    Hughes, Christina Lindsay

    2013-01-01

    Calibration of the liquid krypton calorimeter (LKr) of the NA62 experiment is managed by a set of standalone programs, or an online calibration driver. These programs are similar to those used by NA48, but have been updated to utilize classes and translated to C++ while maintaining a common functionality. A set of classes developed to handle communication with hardware was used to develop the three standalone programs as well as the main driver program for online calibration between bursts. The main calibration driver has been designed to respond to run control commands and receive burst data, both transmitted via DIM. In order to facilitate the process of reading in calibration parameters, a serializable class has been introduced, allowing the replacement of standard text files with XML configuration files.

  12. Electromagnetic calorimeter on liquid krypton

    International Nuclear Information System (INIS)

    Bazzotti, M.; Bianco, G.L.; Lanni, F.; Maggi, B.; Palombo, F.; Sala, A.

    1990-01-01

    This paper reports on use of noble condensed gases as calorimeter media that is attractive due to the possibility to get not only good energy resolution (like in NaI and CsI calorimeters) but better space resolution for photons. Longitudinal segmentation can provide information for particle identification by dE/dx and also e/π-separation based on longitudinal structure of the shower. The best material for this aim is of course liquid Zenon, but it is impossible to get the necessary amount of it in reasonable time. Therefore, the authors have stopped their choice on the next candidate-liquid Krypton (LKr). Its sufficient amount can be obtained before to the beginning of the experiment

  13. Muonium localization in solid krypton

    International Nuclear Information System (INIS)

    Storchak, V.; Cox, S.F.J.; Brewer, J.H.; Morris, G.D.

    1995-06-01

    Muonium spin relaxation in zero, longitudinal and transverse magnetic fields has been studied in solid and liquid krypton in the temperature range from 2 K to 120 K. In the solid at low temperatures, the spin dynamics exhibit features characteristic of a magnetically dilute crystal, permitting measurements of exceptionally low muonium diffusion rates. At the lowest temperatures, a static Kubo-Toyabe relaxation function has been observed for the first time for the atomic muonium state, indicating strong interstitial localization in the Kr lattice at low temperatures; muonium is determined to be localized at the tetrahedral interstitial position. At high temperatures, muonium diffusion in solid Kr exhibits a non-classical behaviour. (author). 31 refs., 6 figs

  14. Krypton tagging velocimetry of an underexpanded jet.

    Science.gov (United States)

    Parziale, N J; Smith, M S; Marineau, E C

    2015-06-01

    In this work, we present the excitation/emission strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV). KTV is performed as follows: (i) seed a base flow with krypton; (ii) photosynthesize metastable krypton atoms with a frequency-doubled dye laser to form the tagged tracer; (iii) record the translation of the tagged metastable krypton by imaging the laser-induced fluorescence (LIF) that is produced with an additional dye laser. The principle strength of KTV, relative to other tagging velocimetry techniques, is the use of a chemically inert tracer. KTV results are presented for an underexpanded jet of three mixtures of varying Kr/N2 concentration. It is demonstrated that KTV can be used in gas mixtures of relatively low krypton mole fraction (0.5% Kr/99.5% N2), and the KTV data from that experiment are found to be in good agreement with an empirical fit found in the literature. We find that KTV is useful to perform instantaneous velocity measurements with metastable krypton as a chemically inert, dilute, long-lifetime tracer in gas-phase flows.

  15. Atomic structure investigation of ionized krypton

    International Nuclear Information System (INIS)

    Kotze, P.B.

    1981-12-01

    The experimental lifetimes of ionized Krypton are discussed. Theoretical, the Coulomb approximation proves to be a reliable tool for the performance of calculations in Krypton II, where in general good agreement between experimental and theoretical lifetimes is reached, but its vulnerability is exposed in the case of Krypton III, where only results concerning levels with a 4p 3 ( 4 S 0 ) parent core can be obtained. Although the single configuration Hartree-Fock approximation turns out to be an adequate way of obtaining wave functions of excited states in Krypton III, cancellation effects resulting from configuration-interaction mixing, make the calculated transition probabilities in Krypton II less reliable. Previous work on configuration-interaction effects in the spectrum of Krypton II (El 76a, El 76b) reveals that good agreement between experimental and theoretical results can be obtained. A systematic theoretical analysis based on the multi-configurarion Hartree-Fock approximation to account for configuration-interaction effects should contribute a great deal to the existing knowledge of the energy spectra of ionized atoms

  16. Preferential site occupancy observed in coexpanded argon-krypton clusters

    International Nuclear Information System (INIS)

    Lundwall, M.; Bergersen, H.; Lindblad, A.; Oehrwall, G.; Svensson, S.; Bjoerneholm, O.; Tchaplyguine, M.

    2006-01-01

    Free heterogeneous argon-krypton clusters have been produced by coexpansion and investigated by means of x-ray photoelectron spectroscopy. By examining cluster surface and bulk binding energy shifts, relative intensities, and peak widths, we show that in the mixed argon-krypton clusters the krypton atoms favor the bulk and argon atoms are pushed to the surface. Furthermore, we show that krypton atoms in the surface layer occupy high-coordination sites and that heterogeneous argon-krypton clusters produced by coexpansion show the same surface structure as argon host clusters doped with krypton. These observations are supported by site-dependent calculations of chemical shifts

  17. Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Oliveira, M. H.; Viana, G. A.; de Lima, M. M.; Cros, A.; Cantarero, A.; Marques, F. C.

    2010-12-01

    Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH4) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

  18. Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Oliveira, M. H. Jr.; Viana, G. A.; Marques, F. C.; Lima, M. M. Jr. de; Cros, A.; Cantarero, A.

    2010-01-01

    Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH 4 ) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

  19. Survey of analytical methods for environmental monitoring of krypton-85

    International Nuclear Information System (INIS)

    Jaquish, R.E.; Moghissi, A.A.

    1973-01-01

    Numerous methods have been developed for measuring krypton-85 in air as krypton ultimately accumulates in air once it is released into the environment. However, krypton-85 can be present in other media such as natural gas from wells stimulated with nuclear devices or in water when krypton-85 is used for aeration studies. Methods for the measurement of ambient levels of krypton-85 require a concentration of krypton from a large air sample of one m 3 or more. If elevated levels are to be measured, carrier krypton may be used provided the contamination of atmospheric krypton with krypton-85 does not interfere with the measurement. In certain cases, such as in the vicinity of nuclear fuel processing plants, direct measurement techniques may be used. A variety of techniques are employed for krypton-85 counting. At low levels, internal gas counting or organic scintillation is used to measure the beta emission of this radionuclide. At higher levels the gamma emission of krypton-85 may be measured using scintillation or solid state gamma spectroscopic methods. Techniques for collection of the sample, concentration of krypton, and radioactivity measurement of krypton-85 are discussed and various processes are critically evaluated and compared

  20. Irrigation with oxygen-nanobubble water can reduce methane emission and arsenic dissolution in a flooded rice paddy

    International Nuclear Information System (INIS)

    Minamikawa, Kazunori; Makino, Tomoyuki; Tago, Kanako; Hayatsu, Masahito; Takahashi, Masayoshi

    2015-01-01

    A remarkable feature of nanobubbles (<10 –6 m in diameter) is their long lifetime in water. Supplying oxygen-nanobubbles (NBs) to continuously flooded paddy soil may retard the development of reductive conditions, thereby reducing the emission of methane (CH 4 ), a potent greenhouse gas, and dissolution of arsenic, an environmental load. We tested this hypothesis by performing a pot experiment and measuring redox-related variables. The NBs were introduced into control water (with properties similar to those of river water) using a commercially available generator. Rice (Oryza sativa L.) growth did not differ between plants irrigated with NB water and those irrigated with control water, but NB water significantly (p < 0.05) reduced cumulative CH 4 emission during the rice-growing season by 21%. The amounts of iron, manganese, and arsenic that leached into the drainage water before full rice heading were also reduced by the NB water. Regardless of the water type, weekly-measured CH 4 flux was linearly correlated with the leached iron concentration during the rice-growing season (r = 0.74, p < 0.001). At the end of the experiment, the NB water significantly lowered the soil pH in the 0–5 cm layer, probably because of the raised redox potential. The population of methanogenic Archaea (mcrA copy number) in the 0–5 cm layer was significantly increased by the NB water, but we found no correlation between the mcrA copy number and the cumulative CH 4 emission (r = –0.08, p = 0.85). In pots without rice plants, soil reduction was not enhanced, regardless of the water type. The results indicate that NB water reduced CH 4 emission and arsenic dissolution through an oxidative shift of the redox conditions in the flooded soil. We propose the use of NB water as a tool for controlling redox conditions in flooded paddy soils. (letter)

  1. CERN: From Russia with krypton

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Full text: Arecent arrival at CERN is a cryostat built under the auspices of thelnternational Science and Technology Center (ISTC), a programme funded by the European Union, Japan, Russia, and the US which aims to promote the integration of former Soviet Union scientists and industry into global research and development activities. The new cryostat, built by Moscowbased Krunichev Enterprises, better known for its involvement in the ''Proton'' space rocket and the ''Mir'' space station, will form a vital part of the NA48 experiment at the SPS synchrotron. NA48, a Cagliari/Cambridge/CERN/ Dubna/Edinburgh/Ferrara/Mainz/Orsay/Perugia/Pisa/Saclay/Siegen/ Turin/Vienna collaboration, aims to study the small asymmetry in the properties of matter and antimatter known as CP violation, and should be fully ready to collect data next year. Through its links with Dubna's Joint Institute of Nuclear Research (JINR), near Moscow, NA48 has launched a number of initiatives designed to involve Russian physicists and industry in the experiment. The bargain 22 tonnes of krypton for NA48's energy-measuring calorimeter were manufactured at a specially- built factory in Russia. INTAS, the European Union-backed scheme for the promotion of cooperation with former Soviet Union scientists, provides funds for Dubna physicists to visit Western Europe. INTAS will also provide computing and networking infrastructure allowing the Russian physicists to participate fully in NA48's programme. As well as the cryostat, NA48's collaborating institutes have placed other orders with Russian suppliers. INFN Pisa has ordered 14,000 electrical feed-though contacts from the Budker Institute in Novosibirsk, whilst Saclay has placed contracts elsewhere for vacuum and other equipment. The new cryostat forms part of a joint project of INFN Pisa and CERN, involving scientists from Dubna, Edinburgh, and Saclay. The Russian part was built by Krunichev

  2. Sustained in situ measurements of dissolved oxygen, methane and water transport processes in the benthic boundary layer at MC118, northern Gulf of Mexico

    Science.gov (United States)

    Martens, Christopher S.; Mendlovitz, Howard P.; Seim, Harvey; Lapham, Laura; D'Emidio, Marco

    2016-07-01

    Within months of the BP Macondo Wellhead blowout, elevated methane concentrations within the water column revealed a significant retention of light hydrocarbons in deep waters plus corresponding dissolved oxygen (DO) deficits. However, chemical plume tracking efforts were hindered by a lack of in situ monitoring capabilities. Here, we describe results from in situ time-series, lander-based investigations of physical and biogeochemical processes controlling dissolved oxygen, and methane at Mississippi Canyon lease block 118 ( 18 km from the oil spill) conducted shortly after the blowout through April 2012. Multiple sensor arrays plus open-cylinder flux chambers (;chimneys;) deployed from a benthic lander collected oxygen, methane, pressure, and current speed and direction data within one meter of the seafloor. The ROVARD lander system was deployed for an initial 21-day test experiment (9/13/2010-10/04/2010) at 882 m depth before a longer 160-day deployment (10/24/2011-4/01/2012) at 884 m depth. Temporal variability in current directions and velocities and water temperatures revealed strong influences of bathymetrically steered currents and overlying along-shelf flows on local and regional water transport processes. DO concentrations and temperature were inversely correlated as a result of water mass mixing processes. Flux chamber measurements during the 160-day deployment revealed total oxygen utilization (TOU) averaging 11.6 mmol/m2 day. Chimney DO concentrations measured during the 21-day deployment exhibited quasi-daily variations apparently resulting from an interaction between near inertial waves and the steep topography of an elevated scarp immediately adjacent to the 21-day deployment site that modulated currents at the top of the chimney. Variability in dissolved methane concentrations suggested significant temporal variability in gas release from nearby hydrocarbon seeps and/or delivery by local water transport processes. Free-vehicle (lander) monitoring

  3. Potential for beneficial use of krypton-85

    International Nuclear Information System (INIS)

    Tingey, G.L.; Jensen, G.A.; McClanahan, E.D.; Lytle, J.M.; Rising, K.R.

    1983-03-01

    Large quantities of krypton-85 (about 42 MCi) are contained in stored power-reactor fuels and about 1 MCi/year in fuels processed at each of the Savannah River and Hanford defense fuel-processing plants. This nuclear byproduct could be a significant material resource if used in specialized applications. Recently a technique for implanting krypton in a growing sputter-deposited metallic film has been developed. This yields a stable, high-concentration source of krypton-85 which may have applications for small power generators. Metal deposits containing up to 14 at. % have been prepared that would give a heat source of 0.9 W/cm 3 if fully enriched krypton-85 were implanted. Potential applications for up to 10-W batteries include power for runway lighting and other specialized military applications in remote locations, power for telephone or radiocommunications in the far North, and power for monitoring equipment for tracking animals. Krypton-85 has the advantage of being environmentally the most acceptable heat-producing radioisotope available for power production. 1 figure

  4. The atmosphere of Mars - Detection of krypton and xenon

    Science.gov (United States)

    Owen, T.; Biemann, K.; Biller, J. E.; Lafleur, A. L.; Rushneck, D. R.; Howarth, D. W.

    1976-01-01

    Krypton and xenon have been discovered in the Martian atmosphere with the mass spectrometer on the second Viking lander. Krypton is more abundant than xenon. The relative abundances of the krypton isotopes appear normal, but the ratio of xenon-129 to xenon-132 is enhanced on Mars relative to the terrestrial value for this ratio. Some possible implications of these findings are discussed.

  5. Environmental behaviour and dosimetry of Krypton-85

    International Nuclear Information System (INIS)

    Patek, P.

    1980-12-01

    Although 85 Kr has only small influence on the total radiation burden to man, monitoring and safety considerations have to be done, especially regarding the operation of fuel reprocessing plants. The natural, military and civilian sources of 85 Kr are discussed and a survey is given on the possibilities of Krypton removal from off-gas streams. Regarding the environmental behaviour of the released Krypton-amounts it was shown, that only the atmospheric dispersion is of influence to the succeeding irradiation of the population. Krypton is transferred to man only by inhalation and remains with different halflives in the human body. The highest absorbed dose is caused by beta-rays to the skin and in the airways of the lungs. While the highest dose equivalent rates to the most exposed individuals are reached by local sources from fuel reprocessing plants, the highest collective effective dose equivalent commitment is reached for global dispersed 85 Kr. (author)

  6. Cylindrical ionization chamber with compressed krypton

    International Nuclear Information System (INIS)

    Kuz'minov, V.V.; Novikov, V.M.; Pomanskii, A.A.; Pritychenko, B.V.; Viyar, J.; Garcia, E.; Morales, A.; Morales, J.; Nunes-Lagos, R.; Puimedon, J.; Saens, K.; Salinas, A.; Sarsa, M.

    1993-01-01

    A cylindrical ionization chamber with a grid is used to search for double positron decay and atomic electron conversion to a positron in 78 Kr. Krypton is the working gas material of the chamber. The spectrometric characteristics of the chamber filled with krypton and xenon are presented. The energy resolution is 2.1% for an energy of 1.84 MeV (the source of γ-quanta is 88 Y) when the chamber is filled with a mixture of Kr+0.2% H 2 under a pressure of 25 atm

  7. Formation of actinide hexafluorides at ambient temperatures with krypton difluoride

    International Nuclear Information System (INIS)

    Asprey, L.B.; Eller, P.G.; Kinkead, S.A.

    1986-01-01

    A second low-temperature agent, krypton difluoride, for generating volatile plutonium hexafluoride is reported (dioxygen difluoride is the only other reported agent). Plutonium hexafluoride is formed at ambient or lower temperature by the treatment of various solid substrates with krypton difluoride. Volatilization of uranium and neptunium from solid substrates using gaseous krypton difluoride is also reported for the first time. The formation of actinide hexafluorides has been confirmed for the reaction of krypton difluoride in anhydrous HF with UO 2 and with uranium and neptunium fluorides at ambient temperatures. Treatment of americium dioxide with krypton difluoride did not yield americium hexafluoride under the conditions studied. 15 references, 2 figures

  8. Absorption process for removing krypton from the off-gas of an LMFBR fuel reprocessing plant

    International Nuclear Information System (INIS)

    Stephenson, M.J.; Dunthorn, D.I.; Reed, W.D.; Pashley, J.H.

    1975-01-01

    The Oak Ridge Gaseous Diffusion Plant selective absorption process for the collection and recovery of krypton and xenon is being further developed to demonstrate, on a pilot scale, a fluorocarbon-based process for removing krypton from the off-gas of an LMFBR fuel reprocessing plant. The new ORGDP selective absorption pilot plant consists of a primary absorption-stripping operation and all peripheral equipment required for feed gas preparation, process solvent recovery, process solvent purification, and krypton product purification. The new plant is designed to achieve krypton decontamination factors in excess of 10 3 with product concentration factors greater than 10 4 while processing a feed gas containing typical quantities of common reprocessing plant off-gas impurities, including oxygen, carbon dioxide, nitrogen oxides, water, xenon, iodine, and methyl iodide. Installation and shakedown of the facility were completed and some short-term tests were conducted early this year. The first operating campaign using a simulated reprocessing plant off-gas feed is now underway. The current program objective is to demonstrate continuous process operability and performance for extended periods of time while processing the simulated ''dirty'' feed. This year's activity will be devoted to routine off-gas processing with little or no deliberate system perturbations. Future work will involve the study of the system behavior under feed perturbations and various plant disturbances. (U.S.)

  9. Process and device for the adsorptive separation of krypton from a krypton/nitrogen gas mixture

    International Nuclear Information System (INIS)

    Ringel, H.; Messler, M.

    1985-01-01

    The gas mixture flows through an adsorption column, which is filled with a means of adsorbing Krypton and nitrogen. The adsorption column is desorbed after adsorption of the gas components by a gaseous flushing material, which flows through the adsorption column in the same direction as the gas mixture. In order to achieve a high degree of separation, the adsorption material is loaded with nitrogen and Krypton from the gas inlet, where Krypton is only absorbed over part of the length of the whole column by the adsorption material. The part of the length is such that on desorption of the adsorption column with the flushing material at first only nitrogen and later only Krypton is obtained at the outlet of the adsorption column. (Waste gas system of a reprocession plant). (orig./HP) [de

  10. Environmental consequences of atmospheric krypton-85

    International Nuclear Information System (INIS)

    Boeck, W.L.

    1978-01-01

    This project examines the thesis that atmospheric background ionization is relevant to the understanding of weather. Projections of future world-wide use of nuclear energy imply that sufficient krypton-85 will be produced and may be released to significantly alter the natural ionization background. The scope of the project includes an assessment of krypton-85 on the electrical aspects of the atmosphere as well as the consequences of an altered electrical state of the atmosphere. The results of a first approximation model for the effects of krypton-85 on the atmosphere show that the electric field at the surface of the ocean would be reduced by about 25 percent and at a continental station by about 15 percent. At about two kilometers altitude, the electric field would be reduced by about 14 percent over the oceans and 16 percent over the land. The effects decrease quickly with increasing altitude. Analytical studies of the equations for fair weather atmospheric electricity yield solutions suitable for the interpretation of time dependent phenomena with periods longer than a few seconds. A brief analysis shows that a perfect assessment is not necessary to make an error-free decision regarding krypton-85 control measures. From the viewpoint of a decision-maker, those aspects that could swing the decision from one alternative to another are priority areas for analysis

  11. Ambient krypton-85 air sampling at Hanford

    International Nuclear Information System (INIS)

    Trevathan, M.S.; Price, K.R.

    1984-10-01

    In the fall of 1982, the Environmental Evaluations Section of Pacific Northwest Laboratory (PNL) initiated a network of continuous krypton-85 air samplers located on and around the Hanford Site. This effort was in response to the resumption of operations at a nuclear fuel reprocessing plant located onsite where krypton-85 was to be released during fuel dissolution. Preoperational data were collected using noble gas samplers designed by the Environmental Protection Agency-Las Vegas (EPA-LV). The samplers functioned erratically resulting in excessive maintenance costs and prompted a search for a new sampling system. State of the art krypton-85 sampling methods were reviewed and found to be too costly, too complex and inappropriate for field application, so a simple bag collection system was designed and field tested. The system is composed of a reinforced, heavy plastic bag, connected to a variable flow pump and housed in a weatherproof enclosure. At the end of the four week sampling period the air in the bag is transferred by a compressor into a pressure tank for easy transport to the laboratory for analysis. After several months of operation, the air sampling system has proven its reliability and sensitivity to ambient levels of krypton-85. 3 references, 3 figures, 1 table

  12. Effect of oxygen and hydrogen on microstructure of pyrolytic carbon deposited from thermal decomposition of methane and ethanol

    Science.gov (United States)

    Ren, Biyun; Zhang, Shouyang; He, LiQun; Gu, Shengyue

    2018-05-01

    Chemical vapor infiltration (CVI) is the most extensive industrial preparation of carbon/carbon (C/C) composites. Precursor affects the CVI process considerably. In the present study, using carbon fiber bundles as preforms, methane and ethanol as precursors, the C/C composites were densified by decomposition of various gases in CVI. The thickness and texture of deposited pyrolytic carbon (PyC) were characterized by polarized light microscopy (PLM). The microstructure of PyC was analyzed by Raman spectroscopy. The morphologies of PyC were characterized by scanning electron microscopy (SEM). The composition of PyC was detected by X-ray photoelectron spectroscopy (XPS). Adding hydrogen in methane precursor resulted in a sharp decrease in the deposition rate and texture of PyC. Mixture of methane and ethanol as the precursor improved the deposition rate and texture remarkably. Besides, O element in ethanol was not remained as a constitution of PyC, and it was removed before the formation of PyC.

  13. Thermochemical Properties of the Lattice Oxygen in W,Mn-Containing Mixed Oxide Catalysts for the Oxidative Coupling of Methane

    Science.gov (United States)

    Lomonosov, V. I.; Gordienko, Yu. A.; Sinev, M. Yu.; Rogov, V. A.; Sadykov, V. A.

    2018-03-01

    Mixed NaWMn/SiO2 oxide, samples containing individual components (Na, W, Mn) and their double combinations (Na-W, Na-Mn, W-Mn) supported on silica were studied by temperature programmed reduction (TPR) and desorption (TPD), and heat flow calorimetry during their reoxidation with molecular oxygen in pulse mode. The NaWMn/SiO2 mixed oxide was shown to contain two different types of reactive lattice oxygen. The weakly-bonded oxygen can be reversibly released from the oxide in a flow of inert gas in the temperature range of 575‒900°C, while the strongly-bonded oxygen can be removed during the reduction of the sample with hydrogen at 700-900°C. The measured thermal effect of oxygen consumption for these two oxygen forms are 185 and 350 kJ/mol, respectively. The amount of oxygen removed at reduction ( 443 μmol/g) considerably exceeded the amount desorbed in an inert gas flow ( 56 μmol/g). The obtained results suggest that the reversible oxygen desorption is due to the redox process in which manganese ions are involved, while during the temperature programmed reduction, mainly oxygen bonded with tungsten is removed.

  14. The Thermal State Computational Research of the Low-Thrust Oxygen-Methane Gaseous-Propellant Rocket Engine in the Pulse Mode of Operation

    Directory of Open Access Journals (Sweden)

    O. A. Vorozheeva

    2014-01-01

    Full Text Available Currently promising development direction of space propulsion engineering is to use, as spacecraft controls, low-thrust rocket engines (RDTM on clean fuels, such as oxygen-methane. Modern RDTM are characterized by a lack regenerative cooling and pulse mode of operation, during which there is accumulation of heat energy to lead to the high thermal stress of RDTM structural elements. To get an idea about the thermal state of its elements, which further will reduce the number of fire tests is therefore necessary in the development phase of a new product. Accordingly, the aim of this work is the mathematical modeling and computational study of the thermal state of gaseous oxygen-methane propellant RDMT operating in pulse mode.In this paper we consider a model RDTM working on gaseous propellants oxygen-methane in pulse mode.To calculate the temperature field of the chamber wall of model RDMT under consideration is used the mathematical model of non-stationary heat conduction in a two-dimensional axisymmetric formulation that takes into account both the axial heat leakages and the nonstationary processes occurring inside the chamber during pulse operation of RDMT.As a result of numerical study of the thermal state of model RDMT, are obtained the temperature fields during engine operation based on convective, conductive, and radiative mechanisms of heat transfer from the combustion products to the wall.It is shown that the elements of flanges of combustion chamber of model RDMT act as heat sinks structural elements. Temperatures in the wall of the combustion chamber during the engine mode of operation are considered relatively low.Raised temperatures can also occur in the mixing head in the feeding area of the oxidant into the combustion chamber.During engine operation in the area forming the critical section, there is an intensive heating of a wall, which can result in its melting, which in turn will increase the minimum nozzle throat area and hence

  15. Flame structure of methane/oxygen shear coaxial jet with velocity ratio using high-speed imaging and OH*, CH* chemiluminescence

    Science.gov (United States)

    Shim, Myungbo; Noh, Kwanyoung; Yoon, Woongsup

    2018-06-01

    In this study, the effects of gaseous methane/oxygen injection velocity ratio on the shear coaxial jet flame structure are analyzed using high-speed imaging along with OH* and CH* chemiluminescence. The images show that, as the velocity ratio is increased, the visual flame length increases and wrinkles of the flame front are developed further downstream. The region near the equivalence ratio 1 condition in the flame could be identified by the maximum OH* position, and this region is located further downstream as the velocity ratio is increased. The dominant CH* chemiluminescence is found in the near-injector region. As the velocity ratio is decreased, the signal intensity is higher at the same downstream distance in each flame. From the results, as the velocity ratio is decreased, there is increased entrainment of the external jet, the mixing of the two jets is enhanced, the region near the stoichiometric mixture condition is located further upstream, and consequently, the flame length decreases.

  16. Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen

    DEFF Research Database (Denmark)

    Bruhn, Dan; Mikkelsen, Teis Nørgaard; Rolsted, M. M. M.

    2014-01-01

    to this, we demonstrated that the UV radiation-induced CH4 emission is independent of leaf area index above unity. Further, we observed that the presence of O2 in the atmosphere was necessary for achieving the highest rates of CH4 emission. Methane formation from leaf surface wax is supposedly a two...... investigated the potential of the leaf surface wax itself as a source of UV radiationinduced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation...

  17. Synthesis and Application of Cerium-Incorporated SBA-16 Supported Ni-Based Oxygen Carrier in Cyclic Chemical Looping Steam Methane Reforming

    Directory of Open Access Journals (Sweden)

    Maryam Meshksar

    2018-01-01

    Full Text Available Hydrogen, as a clean energy carrier, could be produced aided by cyclic oxidation-reduction of oxygen carriers (OCs in contact with carbonaceous fuel in chemical looping steam methane reforming (CL-SMR process. In this study, the cerium was incorporated into the SBA-16 support structure to synthesize the Ni/Ce-SBA-16 OC. The supports were synthesized using hydrothermal method followed by impregnation of Ni and characterized via low and wide angle X-ray diffraction (XRD, Brunauer-Emmett-Teller (BET, scanning electron microscopy (SEM, coupled with energy dispersive X-ray (EDX spectroscopy, and transmission electron micrograph (TEM techniques. In addition, the effect of various Si/Ce molar ratios (20–60 in the support structure, Ni loading (10–30 wt %, reaction temperature (500–750 °C, and life time of optimal oxygen carrier over 16 cycles were investigated. The results of wide angle XRD and SEM revealed that the incorporation of CeO2 in the channels of SBA-16 caused the formation of nickel metallic particles with smaller size and prevents the coke formation. The results showed that OC with 15 wt % Ni and Si/Ce molar ratio of 40 (15Ni/Ce-SBA-16(40 has the best performance when compared with other OCs in terms of catalytic activity and structural properties. The methane conversion of about 99.7% was achieved at 700 °C using 15Ni/Ce-SBA-16(40 OC. We anticipate that the strategy can be extended to investigate a variety of novel modified mesoporous silica as the supporting material for the Ni based OCs.

  18. Facility for the separation of krypton and recuperation of xenon

    International Nuclear Information System (INIS)

    Boell-Djoa, S.H.

    1977-01-01

    A facility is described by means of which the fission inert gases krypton 85 and xenon from spent fuel particles can be separated by fractionated freezing-out and subsequent distillation to such an extent that the xenon contains less than 1 ppb krypton 85. Then, in accordance with the stringent regulations, the krypton can be conveyed to definitive storage in special bottles, whereas the xenon can be released for industrial uses. (orig.) [de

  19. Radioactivity 85Kr in krypton enriched with light isotope

    International Nuclear Information System (INIS)

    Kuz'minov, V.V.; Novikov, V.M.; Pomanskij, A.A.

    1992-01-01

    85 Kr content in krypton enriched with 78 Kr is measured within the frames of experiment for search of binary position decay and conversion of atomic electron into 78 Kr. Voluminous activity in krypton enriched up to 98% 78 Kr equal to 0.206 -0.004 +0.001 Bq/L is obtained which is by 4000 less as compared to natural krypton. 7 refs.; 1 fig.; 1 tab

  20. Hyperpolarized krypton-83 as a contrast agent for magnetic resonance imaging.

    Science.gov (United States)

    Pavlovskaya, Galina E; Cleveland, Zackary I; Stupic, Karl F; Basaraba, Randall J; Meersmann, Thomas

    2005-12-20

    For the first time, magnetic resonance imaging (MRI) with hyperpolarized (hp) krypton-83 (83Kr) has become available. The relaxation of the nuclear spin of 83Kr atoms (I = 9/2) is driven by quadrupolar interactions during brief adsorption periods on surrounding material interfaces. Experiments in model systems reveal that the longitudinal relaxation of hp 83Kr gas strongly depends on the chemical composition of the materials. The relaxation-weighted contrast in hp 83Kr MRI allows for the distinction between hydrophobic and hydrophilic surfaces. The feasibility of hp 83Kr MRI of airways is tested in canine lung tissue by using krypton gas with natural abundance isotopic distribution. Additionally, the influence of magnetic field strength and the presence of a breathable concentration of molecular oxygen on longitudinal relaxation are investigated.

  1. Solubility of krypton in liquid CO2

    International Nuclear Information System (INIS)

    Notz, K.J.; Meservey, A.B.

    1976-06-01

    The solubility of krypton in liquid CO 2 was measured experimentally over essentially the entire liquid range of CO 2 , from -53 to 29 0 C. A tracer technique using 85 Kr was employed, and equilibrated gas-liquid samples were analyzed in situ with a collimated counter. Dilute concentrations of krypton were used, and the data are expressed as a distribution ratio, Y/sub Kr//X/sub Kr/, the log of which is nearly linear with respect to temperature from the lowest temperature to about 20 0 C, above which the values fall off rapidly toward a value of unity at the critical temperature. The numerical values obtained for the distribution ratio increase from 1.44 at 29 0 C to 29.4 at -53 0 C

  2. Surface temperature measurement with radioactive kryptonates

    International Nuclear Information System (INIS)

    Pruzinec, J.; Piatrik, M.

    1976-01-01

    The preparation and use of radioactive kryptonates is described for measuring surface temperatures within the region of 45 to 70 degC. Two samples each were prepared of kryptonated beechwood and hydroquinone on a paper carrier. One sample served as the standard which during the experiment was placed in a thermostat at a constant temperature of 45 degC. The second sample was placed in another thermostat where the temperature changed from 45 to 70 degC. Both samples were in the thermostat for 30 mins. The temperature was raised in steps of 2.5 degC and the time of measurement was constant in both samples. The dependences are given of the drop in activity on temperature for both types of samples. The difference was determined of the drop in activity between the standard and the second sample and the relation for measuring the temperature of the sample was determined therefrom. (J.B.)

  3. Immobilization of krypton in a metal matrix

    International Nuclear Information System (INIS)

    Whitmell, D.S.

    1987-01-01

    The report presents the work carried out on the immobilization of krypton in a metallic matrix by combined ion implantation and sputtering. The process has been successfully tested using 100 curies of fully active krypton in order to demonstrate that the process operates in the radiation levels which will be obtained with active gas at a reprocessing plant. A design study for a plant for fuel reprocessing has shown that the process can be simply operated, without requiring shielded cells. These results, which complete the development programme, indicate that the process is ideal for the containment of kripton arising from the processing of nuclear fuel and that the product will retain the gas under normal storage conditions and also during simulated accident conditions

  4. Occlusion and storage of krypton in solids

    International Nuclear Information System (INIS)

    Vansant, E.F.; Thijs, A.; Peeters, G.; Bievre, P. de; Verhaert, I.

    1984-01-01

    The modification process in order to change in a controlled way the effective pore size of zeolites was optimized by investigating the reaction conditions such as degree of chemisorption, reaction temperature, extent of primary/secondary reactions, type of modifying agent, type of substrate, etc. Different reaction and adsorption conditions have been tested to increase the thermal stability of encapsulated krypton in modified zeolites. The possibilities for zeolite modification have been enlarged by combining boranation and silanation with a thermal treatment of sepiolite, and by the formation of boron-nitrogen compounds in zeolites. Screening experiments, on a semi-industrial scale, of the krypton removal from air were carried out. Two kinds of Kr/air separation have been tested suscessfully on modified mordenite

  5. Ventilation studies of the lung with krypton-81m

    International Nuclear Information System (INIS)

    Klopper, J.F.; Baard, W.P.; Van Heerden, P.D.R.

    1981-01-01

    During a 2-year study period it was found that krypton-81m was useful in clinical practice. During this period 1563 technetium-99m perfusion studies and 807 krypton-81m ventilation studies were performed. A distinct advantage of krypton-81m was the ease with which multiple views could be obtained. These views could be directly compared with those of preceding perfusion studies. However, interruptions in the regular supply of rubidium-81/krypton-81m generators affected 17,1% of perfusion studies and xenon-127 should be a suitable substitute for these periods

  6. Charge state distribution of ionic kryptons after photoionization

    International Nuclear Information System (INIS)

    Cai Xiaohong

    1992-01-01

    Monochromatic X-rays from the 2.3 GeV synchrotron at University Bonn (Germany) are employed for inner shell excitation of krypton. Various ionic kryptons and a number of electrons are produced due to photoionization. In order to study the equilibrium charge state distribution of ionic kryptons, a time of flight mass spectrometer is set up and used to measure the resulting ionic charge spectra with photo energies near the L 1 - , L 2 - and L 3 - absorption edges of krypton. The energy dependence of relative probabilities is presented

  7. Excitation mechanisms in singly ionized krypton laser

    International Nuclear Information System (INIS)

    El-Sherbini, Th.M.

    1982-01-01

    Lifetimes for the low lying 4p 4 4d and 4p 4 5s levels of singly ionized krypton laser are calculated, taking into account configuration interaction effects. The results show that some of these levels are metastable. They also suggest a two step excitation from the ground state of the ion (or the atom) to the upper 4p 4 5p laser levels involving some intermediate metastable states as a possible excitation mechanism. (author)

  8. The NA48 liquid krypton calorimeter

    CERN Document Server

    Gorini, B

    1997-01-01

    The NA48 collaboration goal is to measure the CP violation parameter Re(ɛl/ɛ) at the level of 2 × 10−4. The neutral Kaon decays will be reconstructed by an electromagnetic liquid Krypton calorimeter with fine granularity and a volume almost totally sensible, to obtain excellent position and energy resolution, as well as time resolution. A description of the detector, results from tests of a prototype and the status of the final calorimeter are reported.

  9. Analysis of HARP TPC krypton data

    CERN Document Server

    Dydak, F

    2004-01-01

    This memo describes the procedure which was adopted to equalize the response of the 3972 pads of the HARP TPC, using radioactive 83mKr gas. The results obtained from the study of reconstructed krypton clusters in the calibration data taken in 2002 are reported. Two complementary methods were employed in the data analysis. Compatible results were obtained for channel-to-channel equalization constants. An estimate of the overall systematic uncertainty was derived.

  10. Report of the krypton club: availability of sup(81m)krypton in europe

    International Nuclear Information System (INIS)

    Clark, J.; Watson, I.

    1982-01-01

    An active group of producers of krypton 81m generators has been formed. They met in Liege 27th February 1981 to discuss the technical and logistics problems in making krypton 81m generators more widely available in Europe. A resume of that meeting was prepared and distributed at two major medicine meetings in 1981, Pisa and Berne, in an attempt to alert potential users to the current situation and encourage them to make contact with the production centre most favourably situated logistically. (Author)

  11. Study on the Enhancement Effect of Dielectric Barrier Discharge on the Premixed Methane/Oxygen/Helium Flame Velocity

    International Nuclear Information System (INIS)

    Mu Haibao; Yu Lin; Li Ping; Zhang Guanjun; Tang Chenglong; Wang Jinhua

    2015-01-01

    Recently, plasma-assisted combustion has become a potentially applicable technology in many combustion scenarios. In this paper, a dielectric barrier discharge (DBD) plasma generator is designed to explore the effect of plasma on the CH4 oxidation process, and several properties of combustion are considered. First, in the presence or absence of plasma discharge, physical appearance of the flame is examined and analyzed. Second, the flame propagation velocity is calculated by the flame front extracted from the imaging data with the Bunsen burner method. Finally, the main molecular components and their intensity variation in the flame and the plasma zones are identified with an emission spectrograph to analyze the effect of active species on the combustion process. We also discuss the possible kinetic regime of plasma-assisted combustion. Experimental results imply that plasma discharge applied to the premixed CH4/O2/He mixture significantly raises the flame speed with equivalence ratios ranging from 0.85 to 1.10, with the flame speed improved by 17% to 35%. It can be seen that plasma can improve methane oxidation efficiency in the premixed fuel/oxidizer, especially at a low equivalence ratio. (paper)

  12. Analysis of krypton-85 and krypton-81 in a few liters of air.

    Science.gov (United States)

    Tu, Le-Yi; Yang, Guo-Min; Cheng, Cun-Feng; Liu, Gu-Liang; Zhang, Xiang-Yang; Hu, Shui-Ming

    2014-04-15

    Long-lived radioactive krypton isotopes, (81)Kr (t1/2 = 229,000 year) and (85)Kr (t1/2 = 10.76 year), are ideal tracers. (81)Kr is cosmogenic and can be used for dating groundwater beyond the (14)C age. (85)Kr is a fission product and can be applied in atmospheric studies, nuclear safety inspections, and dating young groundwater. It has long been a challenge to analyze radio-krypton in small samples, in which the total number of such isotopes can be as low as 1 × 10(5). This work presents a system developed to analyze (81)Kr and (85)Kr from a few liters of air samples. A separation system based on cryogenic distillation and gas chromatographic separation is used to extract krypton gas with an efficiency of over 90% from air samples of 1-50 L. (85)Kr/Kr and (81)Kr/Kr ratios in krypton gases are determined from single-atom counting using a laser-based atom trap. In order to test the performance of the system, we have analyzed various samples collected from ambient air and extracted from groundwater, with a minimum size of 1 L. The system can be applied to analyze (81)Kr and (85)Kr in environmental samples including air, groundwater, and ices.

  13. Ionization relaxation in shock-heated krypton-argon mixtures

    International Nuclear Information System (INIS)

    Ezumi, Hiromichi; Kawamura, Masahiko; Yokota, Toshiaki.

    1977-01-01

    The ionization relaxation processes behind shock waves in pure krypton and krypton-argon mixtures have been investigated using a Mach-Zehnder interferometer technique. The incident shock velocity was fixed in the neighborhood of Us=2800 m/sec, and the initial pressure was fixed at 0.95 Torr. The experimental results were compared with theoretical values based on the two-step collisional ionization model taking into account of the wall boundary-layer effect. The slope constants of excitation cross section against relative kinetic energy between krypton atom-atom collisions, krypton atom-electron collisions, and krypton-argon atom-atom collisions were determined to be 4.2 x 10 -19 cm 2 /eV, 1.2 x 10 -17 cm 2 /eV, and 4.2 x 10 -19 cm 2 /eV, respectively. (auth.)

  14. Chromatographic determination of the relative retention of isotopic species of oxygen in methanol and methan-d3-ol

    International Nuclear Information System (INIS)

    Pauls, R.E.; Mahle, N.H.; Shepard, A.T.; Gaw, J.C.; Rogers, L.B.

    1976-08-01

    A high-precision gas chromatograph was used in conjunction with a quadrupole mass filter and an on-line computer to study the fractionation of oxygen isotopes by Porapak T and glycerol in CH 3 OH and CD 3 OH as a function of temperature. Values of relative retention on the order of 1.002 compared favorably with results for the vapor pressure ratio obtained by classical means. Differences from unity were much smaller for the activity-coefficient ratio than for the vapor-pressure ratio. Differential thermodynamic data were also reported

  15. Krypton ventilation imaging using dual-energy CT in chronic obstructive pulmonary disease patients: initial experience.

    Science.gov (United States)

    Hachulla, Anne-Lise; Pontana, François; Wemeau-Stervinou, Lidwine; Khung, Suonita; Faivre, Jean-Baptiste; Wallaert, Benoit; Cazaubon, Jean-François; Duhamel, Alain; Perez, Thierry; Devos, Patrick; Remy, Jacques; Remy-Jardin, Martine

    2012-04-01

    To evaluate the tolerance and level of enhancement achievable after inhalation of stable krypton. This study was approved by the institutional review board and the local ethics committee. Written informed consent was obtained from all subjects. The study was planned as a Fleming two-stage design, enabling one to assess the effectiveness of a newer treatment or technique on a small number of patients. At the end of each stage, the results are computed, and the trial can be stopped if the effectiveness is less than a minimum success rate or greater than an expected success rate. After informed consent was obtained, a total of 32 patients (ie, two successive series of 16 patients each) with severe emphysema underwent a dual-source, dual-energy chest computed tomographic (CT) examination after inhalation of a mixture of stable krypton (80%) and oxygen (20%), with reconstruction of diagnostic and ventilation images. For each patient, two regions of interest were selected on a diagnostic image, one in a region of severe emphysema (presumed to be poorly ventilated or not ventilated) and a second one in a region devoid of structural abnormalities (presumed to be normally ventilated), with measurements of attenuation values on the corresponding ventilation image. All examinations were successfully performed, without adverse effects. Differences in attenuation between normal lung and emphysematous areas were found in 28 patients (88%; 95% confidence interval: 71%, 96.5%). The maximal level of attenuation within normal lung was 18.5 HU. Krypton attenuation difference between normal and emphysematous lung was significant, with a median value of 51.8% (P krypton and its excellent clinical tolerance makes this gas eligible for ventilation CT examinations. © RSNA, 2012.

  16. Krypton-85 storage in sputter-deposited amorphous metals

    International Nuclear Information System (INIS)

    Tingey, G.L.; McClanahan, E.D.; Lytle, J.M.; Gordon, N.R.; Knoll, R.W.

    1982-06-01

    After comparing options for storing radioactive krypton gas, the United States Department of Energy selected ion implantation of the gas into a sputter-deposited metal matrix as the reference process. This technique is being developed with pilot-scale testing and further characterization of the deposited product. The process involves implanting krypton atoms into a growing deposit during the sputtering process. An amorphous metal deposit of nominal composition Ni 0 81 La 0 09 Kr 0 10 has been selected for further studies because of the high krypton loading, high sputtering yield, relatively low cost of the metallic components, resistance to corrosion, and stability of the product. The krypton release from this amorphous metal is described as an activated diffusion process which increases linearly with the square root of time. Studies of krypton release rate as a function of temperature were completed and an activation energy for the diffusion of 70 kcal/mole obtained. From these data, we estimated that the krypton release during the first ten years would be 0.5% for a maximum temperature of 350 0 C. The actual release of the krypton during storage was projected to be lower by a factor of 10 7 with the maximum temperature only 220 0 C. Thermal analysis studies show two energy releases occurring with krypton-containing alloys: one associated with recrystallization of the amorphous alloy and a second associated with krypton release. The total energy release between 100 and 800 0 C was less than 50 cal/g. Estimates are given for the cost of operation of the ion implantation process for solidification of the krypton-85 from a 2000-tonne heavy metal/year reprocessing plant. The present value costs, in 1981 dollars including capital and operating costs and assuming a 30-year life, are about $26M for the lifetime of the plant. Annual energy consumption of the process was estimated to be 3.9 M kWh/year

  17. The distribution, atmospheric transfer, and assessment of krypton-85; Distribution, transfert atmospherique et bilan du krypton-85

    Energy Technology Data Exchange (ETDEWEB)

    Pannetier, R [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-06-01

    Techniques for sampling and measuring krypton-85 have been developed which allowed to determine its geographical distribution. From its use as a tracer, an evaluation of the air masses which cross over the subtropical fronts has been derived. Besides, the stratospheric character of air pollution by krypton-85 at the level of the antarctic soil has been shown out. Levels of krypton-85 seem to point out to an underestimation of the assessment of nuclear explosion fission energies as adopted by the United Nations Scientific committee on the effects of atomic radiation and emphasize the need to set limits as soon as possible to the amounts of krypton-85 released to the atmosphere by fuel-reprocessing plants. (author) [French] La mise au point de techniques de prelevement et de mesure du krypton-85 atmospherique a permis de determiner sa repartition geographique. De son utilisation comme traceur on deduit une evaluation des masses d'air qui traversent les fronts subtropicaux. Par ailleurs, le caractere stratospherique de la pollution de l'air par le krypton-85 au niveau du sol antarctique est mis en evidence. Le bilan du krypton-85 semble reveler une sous-estimation du bilan des energies de fission des explosions adopte par le Comite scientifique des Nations Unies et souligne la necessite de limiter des que possible les quantites de krypton-85 rejetees dans l'atmosphere par les usines de traitement de combustibles irradies. (auteur)

  18. Theory of attosecond absorption spectroscopy in krypton

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Lindroth, Eva; Madsen, Lars Bojer

    2012-01-01

    A theory for time-domain attosecond pump–attosecond probe photoabsorption spectroscopy is formulated and related to the atomic response. The theory is illustrated through a study of attosecond absorption spectroscopy in krypton. The atomic parameters entering the formulation such as energies...... of the hole in this manner. In a second example, a hole is created in an inner shell by the first pulse, and the second probe pulse couples an even more tightly bound state to that hole. The hole decays in this example by Auger electron emission, and the absorption spectroscopy follows the decay of the hole...

  19. Nitrogen-fixing methane-utilizing bacteria

    NARCIS (Netherlands)

    Bont, de J.A.M.

    1976-01-01

    Methane occurs abundantly in nature. In the presence of oxygen this gas may be metabolized by bacteria that are able to use it as carbon and energy source. Several types of bacteria involved in the oxidation of methane have been described in literature. Methane-utilizing bacteria have in

  20. Solid state storage of radioactive krypton in a silica matrix

    International Nuclear Information System (INIS)

    Tingey, G.L.; Lytle, J.M.; Gray, W.J.; Wheeler, K.R.

    1980-12-01

    The feasibility of loading a low density SiO 2 glass with krypton for storage of radioactive 85 Kr has been demonstrated by studies using non-radioactive krypton. A 96% SiO 2 glass with 28% porosity was heated at an elevated pressure of Kr gas to a temperature of 850 to 900 0 C and held at that temperature to sinter the glass-krypton composite to a density of about 2 g/cm 3 . A krypton content of 30 cm 3 of Kr(STP)/cm 3 of glass has been demonstrated when loading pressures of 140 MPa are used. Krypton release rates from the glass are lower than reported for any other waste form considered currently. At 420 0 C a diffusion parameter, D/r 0 2 , of 8.66 x 10 -13 min -1 was determined which leads to a total release of 0.7% of the krypton in 10 years. Release rates increase moderately with increasing temperature up to 600 0 C and increase rapidly above 600 0 C. The lower loading pressures (about 40 MPa) may appear to yield a more favorable product from the point of view of krypton release than the high pressures. Advantages and disadvantages of the technique are given in the conclusions section

  1. Update and improvement of the global krypton-85 emission inventory.

    Science.gov (United States)

    Ahlswede, Jochen; Hebel, Simon; Ross, J Ole; Schoetter, Robert; Kalinowski, Martin B

    2013-01-01

    Krypton-85 is mainly produced in nuclear reactors by fission of uranium and plutonium and released during chopping and dissolution of spent fuel rods in nuclear reprocessing facilities. As noble gas it is suited as a passive tracer for evaluation of atmospheric transport models. Furthermore, research is ongoing to assess its quality as an indicator for clandestine reprocessing activities. This paper continues previous efforts to compile a comprehensive historic emission inventory for krypton-85. Reprocessing facilities are the by far largest emitters of krypton-85. Information on sources and calculations used to derive the annual krypton-85 emission is provided for all known reprocessing facilities in the world. In addition, the emission characteristics of two plants, Tokai (Japan) and La Hague (France), are analysed in detail using emission data with high temporal resolution. Other types of krypton-85 sources are power reactors, naval reactors and isotope production facilities. These sources contribute only little or negligible amounts of krypton-85 compared to the large reprocessing facilities. Taking the decay of krypton-85 into account, the global atmospheric inventory is estimated to about 5500 PBq at the end of 2009. The correctness if the inventory has been proven by meteorological simulations and its error is assumed to be in the range of a few percent. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Radioactive 85Kr in krypton enriched with a light isotope

    International Nuclear Information System (INIS)

    Kuz'minov, V.V.; Novikov, V.M.; Pomanskii, A.A.; Pritychenko, B.V.; Vieiar, J.; Garcia, E.; Morales, A.; Morales, J.; Nunes-Lagos, R.; Piumendon, J.

    1993-01-01

    Radioactive krypton 85, a product of nuclear power generation, is known to be accumulating in the atmosphere continuously. Its volumetric activity in natural krypton is 700-800 Bq/liter. This can cause difficulties, e.g., in the fabrication of nuclear radiation detector for high-mass krypton. Krypton with a reduced 85 Kr content can be obtained by isotope separation. As part of an experiment to look for two-positron decay and conversion of an atomic electron to a positron in 78 Kr, Saenz measured the 85 Kr content in 78 Kr-enriched krypton. A mixture of two 85 Kr samples was used as the working substance of a cylindrical ionization chamber. The useful volume (1.33 liter) of the chamber contained 35.3 liters of gas at ∼2.5 kPa. The energy resolution of the detector at an energy of 0.511 MeV was 3.8%. The measurements were made in a passive lead shield 20 cm thick in an underground laboratory at a depth of 675 m water equivalent. Results are presented for counting rates in low-energy regions, contribution of krypton-85 to background, and the volumetric activity of krypton-85

  3. Solubility of krypton in hydrofracture grout at elevated pressures

    International Nuclear Information System (INIS)

    Fitzgerald, C.L.; Mailen, J.C.

    1982-01-01

    The solubilities of krypton in water, simulated waste solution, and simulated grout at about 25 0 C and to pressures of 150 atm have been determined. The results of these studies show that preliminary calculations of krypton solubility based on the aqueous component of the hydrofracture grout were overly pessimistic. The volume of noble gas generated annually by the reference reprocessing plant would be soluble in the annual hydrofracture grout injection at ORNL at about 10 atm. The amount of krypton in the gas phase would depend on the amount of air in the hydrofracture grout mixture. At 34 atm, and with a small air volume relative to the injected krypton, the krypton would constitute about 30% of the gas bubbles. The disposal of krypton via injection with hydrofracture grout seems to be a viable process. The next logical steps would be to determine the krypton diffusion rate at injection conditions, and possibly to perform a test injection. At present, the schedule for future work is uncertain since funds for this project have been reduced significantly

  4. Update and improvement of the global krypton-85 emission inventory

    International Nuclear Information System (INIS)

    Ahlswede, Jochen; Hebel, Simon; Ross, J. Ole; Schoetter, Robert; Kalinowski, Martin B.

    2013-01-01

    Krypton-85 is mainly produced in nuclear reactors by fission of uranium and plutonium and released during chopping and dissolution of spent fuel rods in nuclear reprocessing facilities. As noble gas it is suited as a passive tracer for evaluation of atmospheric transport models. Furthermore, research is ongoing to assess its quality as an indicator for clandestine reprocessing activities. This paper continues previous efforts to compile a comprehensive historic emission inventory for krypton-85. Reprocessing facilities are the by far largest emitters of krypton-85. Information on sources and calculations used to derive the annual krypton-85 emission is provided for all known reprocessing facilities in the world. In addition, the emission characteristics of two plants, Tokai (Japan) and La Hague (France), are analysed in detail using emission data with high temporal resolution. Other types of krypton-85 sources are power reactors, naval reactors and isotope production facilities. These sources contribute only little or negligible amounts of krypton-85 compared to the large reprocessing facilities. Taking the decay of krypton-85 into account, the global atmospheric inventory is estimated to about 5500 PBq at the end of 2009. The correctness if the inventory has been proven by meteorological simulations and its error is assumed to be in the range of a few percent. - Highlights: ► Krypton-85 is mainly produced in nuclear reactors and released during reprocessing. ► Krypten-85 can be possibly used as an indicator for clandestine reprocessing. ► This work provides an up-to-date global krypton-85 emission inventory. ► The inventory includes emissions from all possible artificial sources.

  5. A method for measurement of the krypton-85-content in the atmosphere

    International Nuclear Information System (INIS)

    Stockburger, H.; Sittkus, A.

    1975-01-01

    To measure the Kr-85 content in the atmosphere we developed a simple method. Within a time internal of five to ten days (depending on the moisture of the air) five to ten m 3 of air (NTP) are pumped through activated carbon (pressure 300 torr, temperature 77 K). When sampling time is over, the carbon is heated to 470 K. This gives a gas sample of 4 l with more than 90% of the atmospherical krypton in 3 hours. With a further step of enrichment, the volume of the sample is reduced to 100 ml. The final separation of krypton from O 2 , N 2 , CO, CO 2 and Xe is made by gaschromatography at room temperature with methane as eluent gas (duration 25 min). The Kr-fraction is transported to a proportional counter (200 ml). The overall yield is 90%. The overall error of the Kr-85-content is near 1%. Data are given for the time of 15.6.1973 to 29.12.1974. (orig.) [de

  6. The Liquid Krypton Calorimeter Cryogenics for the NA48 Experiment

    CERN Document Server

    Bremer, J; Dauvergne, J P; Gonidec, A; Kesseler, G; Kubischta, Werner; Linser, G; Schinzel, D; Taureg, Hans; Wertelaers, Piet

    1998-01-01

    The NA48 cryogenic system has to provide stable thermal conditions (120 K) in a 9000 liter liquid krypton calorimeter, and has to ensure safe and loss free storage of the liquid during idle periods. Direct cooling of the krypton by nitrogen is used in emergency cases, while an intermediate cooler, containing saturated liquid argon at around 10 bar (117 K) is used under normal operation conditions when high thermal stability is needed. The krypton pressure is, during data taking, regulated to a value of (1.05 ± 0.01) bar for a period of about 8 months of continuous operation of the calorimeter.

  7. Technical feasibility of krypton-85 storage in sodalite

    International Nuclear Information System (INIS)

    Benedict, R.W.; Christensen, A.B.; Del Debbio, J.A.; Keller, J.H.; Knecht, D.A.

    1979-01-01

    Based on these experimental results, the process that is technically feasible for a reference 2000 metric ton of heavy metal (MTHM) per year reprocessing plant producing approx. 17 MCi or approx. 190 m 3 at STP would encapsulate krypton at approx. 20 cm 3 /g from krypton at temperatures greater than 575 0 C and pressures greater than 1600 atm with one batch a day in a 58-L high pressure vessel. Based on preliminary measurements at 500 0 C, the same process also would be feasible for a 70% krypton and 30% xenon mixture. 7 figures

  8. The study of radiochemical separation methods on gaseous Fission product krypton-88

    International Nuclear Information System (INIS)

    Yang Zhihong; Zhang Shengdong; Yang Lei; Ding Youqian; Sun Hongqing; Ma Peng

    2012-01-01

    Half-life of krypton-88 is 2.84 hours, high fission yields and a relatively large gamma branching ratio is had. The gas is short-lived fission products in burnup measurements. Only New fission products can extract from extraction in gas of fissile irradiation target. But krypton-88 with krypton-85, krypton-87, xenon -135, and xenon-138 is coexisted together, thus radiochemical separation must quickly taken. selected the irradiation time is 1-2 hours and cooling time is best 2 hours for sample preparation, krypton and xenon were separated using activated carbon adsorption, the ratio of krypton and xenon were measured by gamma spectroscopy. Then according to the ratio of krypton-85 and xenon-125 count rate coefficient around separation were calculated yield of krypton and decontamination factor of xenon and the final the yield of krypton-85 is calculated. (authors)

  9. The distribution, atmospheric transfer, and assessment of krypton-85

    International Nuclear Information System (INIS)

    Pannetier, R.

    1968-06-01

    Techniques for sampling and measuring krypton-85 have been developed which allowed to determine its geographical distribution. From its use as a tracer, an evaluation of the air masses which cross over the subtropical fronts has been derived. Besides, the stratospheric character of air pollution by krypton-85 at the level of the antarctic soil has been shown out. Levels of krypton-85 seem to point out to an underestimation of the assessment of nuclear explosion fission energies as adopted by the United Nations Scientific committee on the effects of atomic radiation and emphasize the need to set limits as soon as possible to the amounts of krypton-85 released to the atmosphere by fuel-reprocessing plants. (author) [fr

  10. Krypton excimer laser oscillation by discharge pumping

    International Nuclear Information System (INIS)

    Shirai, Takahiro; Tabe, Yoshitaka; Kubodera, Shoichi; Sasaki, Wataru; Kawanaka, Junji

    2001-01-01

    We have demonstrated vacuum ultraviolet (VUV) laser oscillation of the krypton excimer (Kr 2 *) excited by a compact self-sustained discharge device. We have observed a spectral narrowing of the Kr 2 * emission centered at 147.8 nm. A deconvoluted spectral width is 0.5 nm (FWHM), which reveals a contrast to a 13 nm spectral width of the spontaneous emission. The Kr 2 * intensity has increased one order of magnitude when a charging voltage was increased larger than 29 kV. The success of the lasing in the VUV spectral region has been attributed to the success of a stable glow discharge of Kr at 10 atm. The pulse width of the VUV laser radiation is 400 ns (FWHM). The maximum output energy measured is as large as 150 μJ. (author)

  11. Application of krypton-85 in groundwater dating

    International Nuclear Information System (INIS)

    Rozanski, K.

    1979-01-01

    The method for determination 85 Kr activity in groundwater and its application in isotope hydrology is presented. Various aspects of 85 Kr presence in the earth's ecosphere are discussed in the first part of the paper. The method for 85 Kr activity measurement in groundwater is presented in the second part of the paper. Analytical procedure consists of the following steps: extraction of the gases dissolved in water sample, separation of the Ar+Kr mixture from the gases, 85 Kr activity measurement in miniature proportional counter, mass spectrometry determination of the krypton gas volume in the proportional counter. About 7 days is necessary for complete analysis of one sample - the error of analysis not exceeds 10 per cent. The results of 85 Kr activity measurements (together with tritium and carbon 14 C determinations) in 14 different water samples allowed to verify usefulness of 85 Kr dating of young water. (author)

  12. Electron impact ionization of large krypton clusters

    Institute of Scientific and Technical Information of China (English)

    Li Shao-Hui; Li Ru-Xin; Ni Guo-Quan; Xu Zhi-Zhan

    2004-01-01

    We show that the detection of ionization of very large van der Waals clusters in a pulsed jet or a beam can be realized by using a fast ion gauge. Rapid positive feedback electron impact ionization and fragmentation processes,which are initially ignited by electron impact ionization of the krypton clusters with the electron current of the ion gauge, result in the appearance of a progressional oscillation-like ion spectrum, or just of a single fast event under critical conditions. Each line in the spectrum represents a correlated explosion or avalanche ionization of the clusters.The phenomena have been analysed qualitatively along with a Rayleigh scattering experiment of the corresponding cluster jet.

  13. Beam-foil level lifetimes in krypton III

    International Nuclear Information System (INIS)

    Coetzer, F.J.; Kotze, P.B.; Westhuizen, P. van der

    1982-01-01

    The radiative lifetimes of levels in doubly-ionized Krypton have been measured after foil excitation of a beam of Krypton particles in the wavelength range 120-500 nm. The results are compared with the experimental values obtained by Fink et al., as well as theoretical values resulting from Coulomb (C.A.) and single configuration Hartree-Fock (H.F.) calculations. (orig.)

  14. Climate aspects of radioactive trace gases, especially krypton-85

    International Nuclear Information System (INIS)

    Kollert, R.; Butzin, M.

    1990-01-01

    The amount of krypton 85 currently present in the atmosphere is 3.300 Peta Bq. This atmospheric krypton contamination stems from atom bomb tests of the past and from nuclear power plants as well as spent fuel reprocessing plants. The paper investigates the air-electric and air-chemical impact of Kr-85 on the atmosphere and makes a forecast of the future Kr-85 contamination. (DG) [de

  15. Desublimation of krypton from a noncondensable carrier gas

    International Nuclear Information System (INIS)

    Eby, R.S.

    1978-09-01

    A study was conducted to obtain column concentration profiles and point buildup rates for a cold trap freezing out krypton from a nitrogen carrier gas stream and to compare those experimentally obtained profiles with profiles generated from a theoretical model. Profiles were obtained over a range of flow conditions from 0.14 to 1.06 standard cubic feet per minute, krypton feed gas concentrations varied from 5.2 to 13.5%, and cold trap operating temperatures from -281 to -312 0 F. Gamma scintillation techniques using tracer amounts of krypton-85 provided the major analytical tool employed in the investigation. Data obtained from the experiments indicate that if values for the density and thermal conductivity of the krypton frost are known, the model can accurately predict krypton loading profiles in the cold trap. The frost density and frost conductivity appear to be functions of the freeze-out temperature and condensable krypton concentration. A discussion of cold trapping theory, a description of the experimental apparatus and tests performed, and an explanation of the usefulness of the model as a design tool for engineering use are included

  16. Spectra of heliumlike krypton from tokamak fusion test reactor plasmas

    International Nuclear Information System (INIS)

    Bitter, M.; Hsuan, H.; Bush, C.; Cohen, S.; Cummings, C.J.; Grek, B.; Hill, K.W.; Schivell, J.; Zarnstorff, M.; Smith, A.; Fraenkel, B.

    1993-04-01

    Krypton has been injected into ohmically-heated TFTR plasmas with peak electron temperatures of 6 key to study the effects of krypton on the plasma performance and to investigate the emitted krypton line radiation, which is of interest for future-generation tokamaks such as ITER, both as a diagnostic of the central ion temperature and for the control of energy release from the plasma by radiative cooling. The emitted radiation was monitored with a bolometer array, an X-ray pulse height analysis system, and a high-resolution Johann-type crystal spectrometer; and it was found to depend very sensitively on the electron temperature profile. Satellite spectra of heliumlike krypton, KrXXXV, near 0.95 Angstrom including lithiumlike, berylliumlike and boronlike features were recorded in second order Bragg reflection. Radiative cooling and reduced particle recycling at the plasma edge region were observed as a result of the krypton injection for all investigated discharges. The observations are in reasonable agreement with modeling calculations of the krypton ion charge state distribution including radial transport

  17. Physical properties and heat transfer characteristics of materials for krypton-85 storage

    International Nuclear Information System (INIS)

    Christensen, A.B.

    1977-09-01

    Krypton-85 decay results in heat generation, and the subsequent temperature increase in the krypton-85 storage media must be evaluated. This report compiles the physical properties of krypton and of potential krypton-85 storage materials which are required to calculate the maximum temperature developed during storage. Temperature calculations were made for krypton-85 stored as a gas or immobilized solid in steel storage cylinders. The effects of krypton-85 loading, cylinder radius, storage media properties, and exterior cooling on storage temperature were shown

  18. The releases of krypton-85 and tritium to the environment and tritium to krypton-85 ratios as source indicators

    International Nuclear Information System (INIS)

    Schroeder, K.J.P.; Roether, W.

    1975-01-01

    More than 95% of the krypton-85 that is at present observed in the environment on a global scale originates from the combined releases following nuclear-power generation and plutonium production, while atmospheric fusion-bomb testing accounts for the same percentage of the global tritium. The global inventories at the end of 1973 were 55 MCi (estimated uncertainty +- 10%) of krypton-85, and 2900 MCi (+- 25%) of tritium. From the excess of the global krypton-85 inventory over the amounts accounted for by the sources other than plutonium production, it is concluded that 130 tonnes of plutonium-239 have been produced up to 1970. Pronounced fractionation occurs between atmosphere and hydrosphere, in the sense that the concentration of krypton-85 is lowered, and that of tritium (being overwhelmingly in the form of a water molecule, HTO) is greatly increased, in the hydrosphere. Largely as a consequence of this fractionation, the environmental tritium to krypton-85 ratios cover a wide range, with values lowest in the troposphere (typical order of magnitude 10 -1 Ci/Ci) and highest in continental surface water (of the order of 10 5 ). Preliminary oceanic krypton-85 data are reported, which indicate that the concentration decrease with depth in the ocean is very similar for both nuclides. Effluents from nuclear power reactors and reprocessing plants have tritium to krypton-85 ratios that do not differ markedly from those found at present in the troposphere; on the other hand, the very high ratios that are typical of the hydrosphere may offer opportunities of detecting such effluents in the hydrosphere on the basis of tritium to krypton-85 ratios. Considerable uncertainties in the ratios of the effluents have, however, to be anticipated, arising from varying, and fluctuating, fractionation between the two nuclides in the release processes. (author)

  19. An evaluation of krypton propellant in Hall thrusters

    Science.gov (United States)

    Linnell, Jesse Allen

    Due to its high specific impulse and low price, krypton has long sparked interest as an alternate Hall thruster propellant. Unfortunately at the moment, krypton's relatively poor performance precludes it as a legitimate option. This thesis presents a detailed investigation into krypton operation in Hall thrusters. These findings suggest that the performance gap can be decreased to 4% and krypton can finally become a realistic propellant option. Although krypton has demonstrated superior specific impulse, the xenon-krypton absolute efficiency gap ranges between 2 and 15%. A phenomenological performance model indicates that the main contributors to the efficiency gap are propellant utilization and beam divergence. Propellant utilization and beam divergence have relative efficiency deficits of 5 and 8%, respectively. A detailed characterization of internal phenomena is conducted to better understand the xenon-krypton efficiency gap. Krypton's large beam divergence is found to be related to a defocusing equipotential structure and a weaker magnetic field topology. Ionization processes are shown to be linked to the Hall current, the magnetic mirror topology, and the perpendicular gradient of the magnetic field. Several thruster design and operational suggestions are made to optimize krypton efficiency. Krypton performance is optimized for discharge voltages above 500 V and flow rates corresponding to an a greater than 0.015 mg/(mm-s), where alpha is a function of flow rate and discharge channel dimensions (alpha = m˙alphab/Ach). Performance can be further improved by increasing channel length or decreasing channel width for a given flow rate. Also, several magnetic field design suggestions are made to enhance ionization and beam focusing. Several findings are presented that improve the understanding of general Hall thruster physics. Excellent agreement is shown between equipotential lines and magnetic field lines. The trim coil is shown to enhance beam focusing

  20. Adsorption of krypton from helium by low temperature charcoal

    International Nuclear Information System (INIS)

    Cooper, M.H.; Simmons, C.R.; Taylor, G.R.

    1975-01-01

    Adsorption of krypton from helium by charcoal at temperatures from -100 0 C to -140 0 C was experimentally investigated to verify adsorption system design methods and to determine effects of regeneration for the Gas Purification System of the Liquid-Metal Fast Breeder Reactor. Helium with two krypton concentrations, traced by krypton-85 at 0.0044 μCi/cm 3 , was passed through a 1/2-inch diameter, three-inch long trap packed with coconut charcoal. Breakthrough curves were measured by continuously recording the activity of the effluent gas using a sampler with a krypton-85 detection limit of about 5 x 10 -7 μCi/cm 3 . Experimental breakthrough curves with continuous feed for both concentrations and for superficial gas velocities of 5 to 28 cm/sec were closely fitted when the pore diffusion term was omitted from the Anzelius linear equilibrium adsorption model indicating that the adsorption process for this system was controlled by gas phase mass transport kinetics. Adsorption capacities determined in these experiments at -140 0 C agreed closely with published data. A discontinuity, however, was observed in the krypton adsorption coefficient between -100 and -120 0 C. This discontinuity may be caused by capillary condensation of krypton in the charcoal pores. Breakthrough times for pulse experiments at 400 ppM (vol.) krypton concentration were several times greater than breakthrough for continuous feed experiments at equivalent conditions. The differences in breakthrough times indicate that the adsorption isotherms are non-linear in this concentration range. Regeneration experiments showed that purging with helium at room temperature for 16 hours was inadequate, since lower breakthrough times were obtained after this treatment. Regeneration under vacuum at 100 0 C or 200 0 C for 16 hours resulted in satisfactory regeneration (i.e., no reduction in breakthrough times occurred in subsequent runs). (U.S.)

  1. Partitioning of krypton-85 in liquid scintillation cocktail

    International Nuclear Information System (INIS)

    Hohorst, F.A.; Sherlock, M.A.

    1994-12-01

    Krypton is one of the noble gases. As such, it forms compounds only with exceptionally strong oxidizing agents. The concentration of krypton in air is 1.139 parts per million by volume. In general, its behavior is best described as that of an ideal gas. Krypton-85 is the longest lived of the common radioactive noble gases with a half life of 10.72 years. Gamma radiation at 513.990 keV has an intensity of only 0.434%. Most decay is β - emission with a maximum energy of 687.0 keV and an average energy of 251.4 keV. The analytical chemistry of krypton-85 is driven by these factors. High concentrations may be gamma counted directly. Low levels are typically determined by more sensitive techniques such as liquid scintillation counting (LSC) where detection limits on the order of 1 picocurie (pCi) are routinely achieved. For a 5 standard cubic centimeter (scc) sample, this represents a concentration of 0.2 pCi/scc, well below the DOE Air Immersion Derived Concentration Guideline (G) of 3 pCi/scc. As a gas, krypton in a sealed LSC vial distributes itself between the liquid phase and the gas phase. Some past work has used gamma counting at levels many orders of magnitude greater than those now achievable by LSC to study the distribution of krypton. This effect is of interest in the analytical chemistry of krypton-85 because geometrical considerations influence how much of the material in the gas phase decays generating particles which then impact the liquid phase where they may be counted

  2. Shape Coexistence In Light Krypton Isotopes

    International Nuclear Information System (INIS)

    Clement, E.; Goergen, A.; Bouchez, E.; Chatillon, A.; Korten, W.; Le Coz, Y.; Theisen, Ch.; Huerstel, A.; Lucas, R.; Wilson, J.N.; Andreoiu, C.; Butler, P.; Herzberg, R.-D.; Iwanicki, J.; Jenkins, D.; Jones, G.; Becker, F.; Gerl, J.; Blank, B.; Hannachi, F.

    2005-01-01

    Shape coexistence in the light krypton isotopes was studied in a series of experiments at GANIL using various experimental techniques. A new low-lying 0+ state, a so-called shape isomer, was found in delayed conversion-electron spectroscopy after fragmentation reactions. The systematics of such low-lying 0+ states suggests that the ground states of the isotopes 78Kr and 76Kr have prolate deformation, while states with prolate and oblate shape are practically degenerate and strongly mixed in 74Kr, and that the oblate configuration becomes the ground state in 72Kr. This scenario was tested in experiments performing low-energy Coulomb excitation of radioactive 76Kr and 74Kr beams from the SPIRAL facility. Both transitional and diagonal electromagnetic matrix elements were extracted from the observed γ-ray yields. The results find the prolate shape for the ground-state bands in 76Kr and 74Kr and an oblate deformation for the excited 2 2 + state in 74Kr, confirming the proposed scenario of shape coexistence

  3. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Self-luminous products containing tritium, krypton-85, or..., krypton-85, or promethium-147. (a) Except for persons who manufacture, process, produce, or initially transfer for sale or distribution self-luminous products containing tritium, krypton-85, or promethium-147...

  4. Methane hydroxylation: a biomimetic approach

    International Nuclear Information System (INIS)

    Shilov, Aleksandr E; Shteinman, Al'bert A

    2012-01-01

    The review addresses direct methane oxidation — an important fundamental problem, which has attracted much attention of researchers in recent years. Analysis of the available results on biomimetic and bio-inspired methane oxygenation has demonstrated that assimilating of the experience of Nature on oxidation of methane and other alkanes significantly enriches the arsenal of chemistry and can radically change the character of the entire chemical production, as well as enables the solution of many material, energetic and environmental problems. The bibliography includes 310 references.

  5. Methane production from cheese whey

    Energy Technology Data Exchange (ETDEWEB)

    Yan, J Q; Liao, P H; Lo, K V

    1988-01-01

    Cheese whey was treated in a 17.5-litre laboratory-scale up-flow anaerobic sludge blanket reactor operated over a range of hydraulic retention times and organic loading rates. The reactor performance was determined in terms of methane production, volatile fatty acids conversion and chemical oxygen demand (COD) reduction. At a constant influent strength, the methane production rate decreased with decreasing hydraulic retention time. At constant hydraulic retention time the methane production rate increased as the influent strength was increased up to a concentration of 28.8 g COD litre/sup -1/. The methane production rate was similar for two influent concentrations studied at hydraulic retention times longer than 10 days. The effect of short hydraulic retention times on methane production rate was more pronounced for the higher influent concentration than for the lower influent concentration. The highest methane production rate of 9.57 litres CH/sub 4/ litre/sup -1/ feed day/sup -1/ was obtained at a loading rate of 5.96 g/sup -1/ COD litre/sup -1/ and an influent concentration of 28.8 g COD litre/sup -1/. A high treatment efficiency in terms of chemical oxygen demand reduction was obtained. In general, over 98% removal of chemical oxygen demand was achieved. The results indicated that anaerobic digestion of cheese whey using an upflow sludge blanket reactor could reduce pollution strength and produce energy for a cheese plant.

  6. GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

    Science.gov (United States)

    Hendricks, R. C.; Baron, A. K.; Peller, I. C.

    1975-01-01

    A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

  7. Separation of the fission product noble gases krypton and xenon from dissolver off-gas in reprocessing HTGR-fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bohnenstingl, J.; Djoa, S. H.; Laser, M.; Mastera, S.; Merz, E.; Morschl, P.

    1976-04-15

    This paper describes a process developed for the retainment and separation of volatile (3H, 129 +131I) and gaseous (85Kr, Xe) fission products from the off-gas produced during dissolution of HTGR-fuel. To prevent unnecessary dilution of liberated noble gases by surrounding atmosphere, a helium purge-gas cycle is applied to enable a coarse fractionating of krypton and xenon by cold-trapping at about 80 deg K after precleaning the gas stream. The process consists of the following steps: deposition of droplets and solid aerosols; chemisorption of iodine on silver impregnated silica gel; catalytic removal of nitrogen oxides and oxygen; drying of the process gas stream; final filtering of abraded solids; deposition of xenon in solid form at 80 deg K and low subpressure; deposition of krypton in solid form at 80 deg K after compression to about 6 bar; decontamination of 85krypton-containing xenon by batch distillation for eventual industrial utilization; and removal of nitrogen and argon enrichment during continuous operation in the purge-gas stream by inleaking air with charcoal. A continuously operating dissolver vessel, closed to the surrounding atmosphere, yields a very high content of noble gases, e.g., 0.35 vol % krypton and 2.0 vol % xenon. The presented off-gas treatment unit is operated in cold runs with 1/3 of the full capacity and can treat about 1 m3 STP/h helium, corresponding to a quantity of about 10,000 MW(e) HTGR-fuel reprocessing plant.

  8. Biocatalytic conversion of methane to methanol as a key step for development of methane-based biorefineries.

    Science.gov (United States)

    Hwang, In Yeub; Lee, Seung Hwan; Choi, Yoo Seong; Park, Si Jae; Na, Jeong Geol; Chang, In Seop; Kim, Choongik; Kim, Hyun Cheol; Kim, Yong Hwan; Lee, Jin Won; Lee, Eun Yeol

    2014-12-28

    Methane is considered as a next-generation carbon feedstock owing to the vast reserves of natural and shale gas. Methane can be converted to methanol by various methods, which in turn can be used as a starting chemical for the production of value-added chemicals using existing chemical conversion processes. Methane monooxygenase is the key enzyme that catalyzes the addition of oxygen to methane. Methanotrophic bacteria can transform methane to methanol by inhibiting methanol dehydrogenase. In this paper, we review the recent progress made on the biocatalytic conversion of methane to methanol as a key step for methane-based refinery systems and discuss future prospects for this technology.

  9. The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger

    CERN Document Server

    INSPIRE-00293812; Paoluzzi, Giovanni; Salamon, Andrea; Salina, Gaetano; Santovetti, Emanuele; Scarfi, Francesco M.; Bonaiuto, Vincenzo; Sargeni, Fausto

    2012-01-01

    The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

  10. Krypton red laser photocoagulation of the ocular fundus. 1982.

    Science.gov (United States)

    Yannuzzi, Lawrence A; Shakin, Jeffrey L

    2012-02-01

    The theoretical rationale, the histopathologic evidence, and the preliminary clinical studies related to krypton red laser (KRL) photocoagulation of the ocular fundus are reviewed. The authors report on their experience with currently available laser systems using this wavelength (647.1 nm) for photocoagulation of retinal vascular proliferative diseases and chorioretinal diseases associated with exudative manifestations. A histopathologic and clinical comparison of argon blue-green laser (ABGL), the pure argon green laser (AGL), and the krypton yellow laser (KYL), with reference to photocoagulation treatment of the ocular fundus is also discussed.

  11. Krypton and xenon in the atmosphere of Venus

    Science.gov (United States)

    Donahue, T. M.; Hoffman, J. H.; Hodges, R. R., Jr.

    1981-01-01

    The paper reports a determination by the Pioneer Venus large probe neutral mass spectrometer of upper limits to the concentration of krypton and xenon along with most of their isotopes in the atmosphere of Venus. The upper limit to the krypton mixing ratio is estimated at 47 ppb, with a very conservative estimate at 69 ppb. The probable upper limit to the sum of the mixing ratios of the isotopes Xe-128, Xe-129, Xe-130, Xe-131, and Xe-132 is 40 ppb by volume, with a very conservative upper limit three times this large.

  12. Experience gained in the cryodistillation unit for krypton removal

    International Nuclear Information System (INIS)

    Geens, L.; Collard, G.; Goossens, W.R.A.; Vaesen, P.J.

    1981-08-01

    This unit with a nominal gas throughput of 8.5 g.s -1 has been used to investigate the removal of krypton from reprocessing off-gases under non-radioactive conditions. During the investigation a total operation time of more than 13.000 hours was reached with an average availability factor of 99.36%. The trapping efficiency for krypton was higher than 99.9%. The operation experience acquired indicates some critical aspects for the design of such a unit. The experimental results obtained allow to show the influence of feed pressure and temperature, reflux flow rate and noble gas concentrations on the performance of the unit. (author)

  13. The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger

    CERN Document Server

    INSPIRE-00646848; Fucci, Adolfo; Paoluzzi, Giovanni; Salamon, Andrea; Salina, Gaetano; Santovetti, Emanuele; Scarfi, Francesco M.; Sargeni, Fausto

    2011-01-01

    The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

  14. Device for separating and concentrating rare gases containing krypton gas

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, S; Sugimoto, K

    1975-06-11

    In orer to highly concentrate krypton by means of adsorption and desorption of activated carbon, in a device for continuously separating and concentrating rare gases containing krypton gas by means of adsorbing and desorbing operation of activated carbon, the device includes adsorbers arranged in parallel and more than two stages of adsorbers arranged in series with the first mentioned adsorbers with the amount of activated carbon filled successively reduced, and a cooling mechanism for cooling the adsorbers when adsorbed and a heating mechanism for heating the adsorbers when desorbed.

  15. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

    Science.gov (United States)

    Oswald, Kirsten; Milucka, Jana; Brand, Andreas; Littmann, Sten; Wehrli, Bernhard; Kuypers, Marcel M. M.; Schubert, Carsten J.

    2015-01-01

    Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere. PMID:26193458

  16. Incineration of oxygenated volatile organic compounds. Experimental study and kinetic modeling of the oxidation of methyl ethyl ketone, ethyl acetate and butan-2-ol in methane flames; Incineration de composes organiques volatils oxygenes. Etude experimentale et modelisation cinetique de l'oxydation de la methyl ethyl cetone, de l'acetate d'ethyle et du butan-2-ol dans des flammes de methane

    Energy Technology Data Exchange (ETDEWEB)

    Decottignies, V

    2000-12-01

    This work deals with the low pressure (0.05 atm) degradation of three volatile organic compounds (VOCs): methyl-ethyl-ketone, ethyl acetate and butan-2-ol, in premixed stoichiometric laminar methane flames seeded with 1 to 3% of each VOC. Molar fraction profiles of species have been obtained using microprobe sampling coupled with a gas chromatography and a mass spectroscopy analysis. Temperature profiles have been obtained using the covered thermocouple technique in the presence of the microprobe. The addition of a VOC in the initial reagents mixture leads to an increase of the quantity of intermediate hydrocarbon compounds and in particular of some soot precursor species. The degradation of VOCs leads to the formation of oxygenated intermediates like methanol, dimethyl-ether, acetaldehyde, propanal, acetone and vinyl acetate, the type of VOC having an effect on the quantities produced. The degradation of a VOC can lead to the formation of more toxic or polluting compounds (methyl vinyl ketone, acetic acid and acrolein) than the VOC itself. In the conditions of the study, the intermediate compounds are totally destructed inside the reactional area of the flame front and are no more present in the burnt gases. Sub-mechanisms of VOC oxidation have been developed using experimental observations and the most recent recommendations of the literature. These sub-mechanisms comprise 49 species involved in 241 elementary reactions. Their validation has been performed by comparing the experiment with the kinetic modeling on the molar fraction profiles of the detected species. Experimental data are well reproduced by the model for most species. The addition of a VOC inside the initial reagents mixture creates an important reactivity increase, in particular in the case of butan-2-ol seeded flames. The analysis of reactional ways has permitted to draw out the main reactions responsible for the degradation of the 3 VOCs and the ways of formation and consumption of the

  17. Measurement of krypton-85 in the atmosphere with a portable apparatus

    International Nuclear Information System (INIS)

    Okai, T.

    1984-01-01

    A portable apparatus was developed for the rapid collection, separation and counting of krypton-85 in environmental air samples. The apparatus consists of a molecular sieve trap for the elimination of H 2 O and CO 2 , a charcoal trap for the collection of krypton, a chromatographic column for the isolation of krypton in the air sample and a vial for the disolution of krypton in the scintillation solution. With this apparatus, krypton can be collected from half a cubic meter of air with 94% recovery in about 3 hrs. The measurements of krypton-85 were done several time in Fukuoka area from Jan. 30 to Dec. 9, 1981. The krypton-85 concentration was found to be approximately 21 pCi/m 3 air. The results were compared with those obtained by foreign investigators. (author)

  18. Recovery of krypton-85 from dissolver off-gas streams

    International Nuclear Information System (INIS)

    Law, J.P.; Lamb, K.M.

    1988-01-01

    The Rare Gas Plant at the Idaho Chemical Processing Plant Recovers fission product krypton and xenon from dissolver off gas streams. Recently the system was upgraded to allow processing of hydrogen rich dissolver off-gas streams. A trickle bed hydrogen recombiner was installed and tested. The Rare Gas Plant can now safely process gas streams containing up to 80% hydrogen

  19. Selective adsorption-desorption method for the enrichment of krypton

    International Nuclear Information System (INIS)

    Yuasa, Y.; Ohta, M.; Watanabe, A.; Tani, A.; Takashima, N.

    1975-01-01

    Selective adsorption-desorption method has been developed as an effective means of enriching krypton and xenon gases. A seriesof laboratory-scale tests were performed to provide some basic data of the method when applied to off-gas streams of nuclear power plants. For the first step of the enrichment process of the experiments, krypton was adsorbed on solid adsorbents from dilute mixtures with air at temperatures ranging from -50 0 C to -170 0 C. After the complete breakthrough was obtained, the adsorption bed was evacuated at low temperature by a vacuum pump. By combining these two steps krypton was highly enriched on the adsorbents, and the enrichment factor for krypton was calculated as the product of individual enrichment factors of each step. Two types of adsorbents, coconut charcoal and molecular sieves 5A, were used. Experimental results showed that the present method gave the greater enrichment factor than the conventional method which used selective adsorption step only. (U.S.)

  20. Particle dynamics during electronic sputtering of solid krypton

    DEFF Research Database (Denmark)

    Dutkiewicz, L.; Pedrys, R.; Schou, Jørgen

    1995-01-01

    We have modeled electronic sputtering of solid krypton by excimer production with molecular dynamics. Both excimer evolution in the solid and deexcitation processes have been incorporated in the simulation. The excimer dynamics in the lattice has been analyzed: the excimers formed near the surface...

  1. Design and performance characteristics of a krypton chloride (λ ...

    Indian Academy of Sciences (India)

    2014-01-07

    Jan 7, 2014 ... Development of a discharge-pumped krypton chloride (KrCl) laser operating at 222 nm wavelength is demonstrated. In this paper the design, successful realization and operating characteristics of KrCl excimer laser are reported. The laser is driven by a simple and efficient excitation technique using ...

  2. Innovative method for ultra-sensitive measurement of krypton isotopes

    International Nuclear Information System (INIS)

    Lavielle, B.; Gilabert, E.; Thomas, B.; Rebeix, R.; Canchel, G.; Moulin, C.; Topin, S.; Pointurier, F.

    2015-01-01

    Kr 81 (T 1/2 = 2.29*10 5 y), that is produced in the atmosphere by cosmic rays and Kr 85 (T 1/2 = 10.77 y), that is produced in the fission of nuclear fuels, are considered as the right chronometer elements for the dating of underground waters, polar ice, of for tracking civil and military nuclear activities. The use of Kr 81 and Kr 85 implies the development of extracting lines and detection devices with so high accuracy that only a few thousands of krypton atoms can be detected. The approach developed aims at detecting Kr 81 and Kr 85 in 1 liter of air and 20 liters of water. 3 steps are necessary. The first step consists in separating and purifying the krypton. The extraction of gases from water is made by helium bubbling. Chemically active gases like N 2 , CO 2 , CH 4 and O 2 are eliminated by chemical traps while Ar si separated by cryogenics. The second step involves a double focus mass spectrometer designed to perform an important enrichment in Kr 81 and Kr 85 . The last step is the high-accuracy measurement of krypton isotopes performed with the new tool named FAKIR (Facility for Analyzing Krypton Isotopic Ratios) that is based on UV laser ionization and on the mass-discrimination of the ions through their time of flight

  3. Thermal stability of the krypton Hall effect thruster

    Directory of Open Access Journals (Sweden)

    Szelecka Agnieszka

    2017-03-01

    Full Text Available The Krypton Large IMpulse Thruster (KLIMT ESA/PECS project, which has been implemented in the Institute of Plasma Physics and Laser Microfusion (IPPLM and now is approaching its final phase, was aimed at incremental development of a ~500 W class Hall effect thruster (HET. Xenon, predominantly used as a propellant in the state-of-the-art HETs, is extremely expensive. Krypton has been considered as a cheaper alternative since more than fifteen years; however, to the best knowledge of the authors, there has not been a HET model especially designed for this noble gas. To address this issue, KLIMT has been geared towards operation primarily with krypton. During the project, three subsequent prototype versions of the thruster were designed, manufactured and tested, aimed at gradual improvement of each next exemplar. In the current paper, the heat loads in new engine have been discussed. It has been shown that thermal equilibrium of the thruster is gained within the safety limits of the materials used. Extensive testing with both gases was performed to compare KLIMT’s thermal behaviour when supplied with krypton and xenon propellants.

  4. An experimental investigation of proton-induced phenomena in krypton

    International Nuclear Information System (INIS)

    Mulders, J.J.L.

    1985-01-01

    In this thesis proton-induced phenomena in krypton gas are described. The considered reactions of protons on krypton are both nuclear and atomic. The nuclear conversion processes mainly result in the production of several Rb radioisotopes, such as 81 Rb that is used in 81 Rb-sup(81m)Kr generator systems for medical diagnostics. The irradiation of krypton gas (natural composition) with protons of about 26 MeV can be used for the routine production of 81 Rb from the direct production reaction 82 Kr(p,2n) 81 Rb and from the indirect reaction 82 Kr(p,2n)sup(81m)Rb → 81 Rb. To determine the scattering of protons in krypton gas targets a quantitative autoradiographic technique was developed. Proton profiles have been determined from the proton-induced activity distribution on a copper foil. For the on-line detection of produced Rb radioisotopes several optical detection techniques were investigated. (Auth.)

  5. Inertial fusion energy with krypton fluoride lasers

    International Nuclear Information System (INIS)

    Sethian, J.D.

    2010-01-01

    Complete text of publication follows. We are developing the science and technologies needed for a practical fusion energy source using high energy krypton fluoride (KrF) lasers. The physics basis for this work is a family of simulations that exploit the unique advantages of KrF lasers. KrF lasers provide uniform enough laser light to illuminate the capsule directly, greatly improving the laser-target coupling efficiency, as well as simplifying the target design. KrF's shorter wavelength allows higher ablation pressures and helps suppress laser-plasma instabilities. These advantages are being demonstrated on the NRL Nike KrF laser facility. A particularly promising approach is shock ignition, in which a high intensity laser pulse drives an intense shock at peak compression. Simulations with experimentally benchmarked codes predict a 1 MJ KrF laser can produce 200 MJ of pure fusion energy. We have similarly advanced the laser technology. We have developed a KrF laser, using technologies that scale to a reactor beamline, that fires 5 times per second for long duration runs and is projected be efficient enough for a reactor. The science and the technology for the key components are developed at the same time as part of a coherent system. A multi-institutional team from industry, national labs, and universities has developed credible solutions for these components. This includes methods to fabricate the spherical pellets on mass production basis, a means to repetitively inject the capsules into the chamber and precisely hit them with the laser, scaled tests to develop the laser optics, and designs for the reaction vessel. Based on these advances NRL and its collaborators have formulated a three stage plan that could lead to practical fusion energy on a much faster time scale than currently believed. Stage I develops full scale components: a laser beam line, target factory and injector, and chamber technologies. Stage II is the Fusion Test Facility (FTF). Simulations

  6. The reaction mechanism of the partial oxidation of methane to synthesis gas: a transient kinetic study over rhodium and a comparison with platinum

    NARCIS (Netherlands)

    Mallens, E.P.J.; Hoebink, J.H.B.J.; Marin, G.B.M.M.

    1997-01-01

    The partial oxidation of methane to synthesis gas over rhodium sponge has been investigated by admitting pulses of pure methane and pure oxygen as well as mixtures of methane and oxygen to rhodium sponge at temperatures from 873 to 1023 K. Moreover, pulses of oxygen followed by methane and vice

  7. Improving accuracy and precision of ice core δD(CH4 analyses using methane pre-pyrolysis and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

    Directory of Open Access Journals (Sweden)

    M. Bock

    2014-07-01

    Full Text Available Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4 or δ2H(CH4 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sample amount for δD(CH4 measurements in (ice core air. Pre-concentrated methane is focused in front of a high temperature oven (pre-pyrolysis trapping, and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping, both on a carbon-PLOT capillary at −196 °C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30 mL – at standard temperature and pressure (STP – of air with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4 of about 6 mL (STP or about 500 pmol of pure CH4.

  8. Solid sources of krypton-85; Sources solides de krypton-85; Tverdye istochniki kriptona-85; Fuentes solidas de cripton-85

    Energy Technology Data Exchange (ETDEWEB)

    Puig, J R; Sandier, J [Centre d' Etudes Nucleaires de Saclay (France)

    1962-01-15

    Krypton-85, a {beta}-emitter with a long half-life and low biological hazard, has considerable industrial potentialities. It is difficult, however, to manufacture sources since the element occurs in gaseous form and cannot be chemically fixed. The authors describe a method of krypton-fixation in a macromolecular matrix formed by mass polymerization of a liquid monomer containing krypton; they also give an account of the preparation of two types of source produced in this way-one enclosed in polystyrene, the other in polyvinyl acetate. Such sources lose krypton; the activity of the first decreases by 8 % daily, that of the second by 3 % daily. These apparent decays enable the diffusion coefficients of krypton in these polymers to be calculated. Diffusion appears to be prevented by the cross-linkages which exist in the polymers. (author) [French] Le krypton-85, emetteur {beta} de longue periode et de faible danger biologique, offre des avantages importants pour une utilisation industrielle. Mais la fabrication de sources est difficile du fait que cet element se presente sous forme gazeuse et qu'il ne peut etre fixe chimiquement. Les auteurs exposent une methode de fixation du krypton dans une matrice macromoleculaire formee par la polymerisation en masse d'un monomere liquide contenant le krypton, et decrivent les preparations de deux types de sources realisees sur ce principe - l'une enfermee dans du polystyrene, l'autre dans de l'acetate de polyvinyle. Les sources ainsi obtenues laissent echapper du krypton; leur activite diminue de 8% par jour pour la premiere et de 3% par jour pour la seconde. Ces decroissances apparentes permettent de calculer les coefficients de diffusion du krypton dans ces polymeres. Celle-ci parait empechee par les liaisons de pontage existant dans le polymere. (author) [Spanish] El cripton-85 es un emisor beta de periodo largo y poco peligroso desde el punto de vista biologico, que ofrece considerables ventajas para su empleo en la

  9. Immobilization of krypton-85 in zeolite 5A

    International Nuclear Information System (INIS)

    Christensen, A.B.; Del Debbio, J.A.; Knecht, D.A.; Tanner, J.E.; Cossel, S.C.

    1983-01-01

    This paper describes the technical feasibility and presents a summary of a preconceptual design and cost estimate for a process to immobilize krypton-85 by sintering in zeolite 5A at 700 0 C and 100 MPa for 2 to 4 h. Krypton loading of 30 to 60 m 3 at STP per m 3 solid can be achieved. The initial water concentration in zeolite 5A has a catalytic effect on the sintering rate and must be kept at about 1 wt% by heating prior to the encapsulation run. High initial water loadings and/or encapsulation times longer than 4 h must be avoided because the sintered zeolite 5A recrystallizes to an anorthite-type feldspar and releases the trapped krypton. Data are presented to show how the process conditions affect krypton encapsulation in zeolie 5A and how to assure the quality of the product. By adding a powdered glass frit to the commercial zeolite 5A 2 mm beads, a solid mass is formed during encapsulation, which can be further compacted using standard hot isotatic pressing techniques at 33 MPa and 600 0 C to form a fused glassy matrix enclosing the amorphous zeolite. A process for encapsulating the annual krypton-85 production at a commercial 2000 metric ton of heavy metal spent fuel reprocessing plant is developed. A hot isostatic press (HIP) with an isolated work zone of 8 or 16 L capacity is required to operate for 600 or 300 cycles per year, respectively. Existing HIP technology uses work zones from 1 to 3500 L capacity at similar production rates. A combined encapsulation/compaction cycle is proposed as an option to most effectively immobilize the krypton and the zeolite. A preconceptual design and cost estimate is given for a commercial-scale Kr encapsulation facility. The facility is designed to withstand a worst case rupture of the HIP. The maximum lease is estimated to result in an off-site dose well below accident protective action guidance levels

  10. Agricultural methanization

    International Nuclear Information System (INIS)

    2011-01-01

    After having briefly outlined the interest of the development of methanization of agricultural by-products in the context of struggle against climate change, and noticed that France is only now developing this sector as some other countries already did, this publication describes the methanization process also called anaerobic digestion, which produces a digestate and biogas. Advantages for the agriculture sector are outlined, as well as drawbacks and recommendations (required specific technical abilities, an attention to the use of energetic crops, an improved economic balance which still depends on public subsidies, competition in the field of waste processing). Actions undertaken by the ADEME are briefly evoked

  11. Empirical evaluation of the radiative cooling coefficient for krypton gas in the FTU plasma

    International Nuclear Information System (INIS)

    Fournier, K.B.; Pacella, D.; Mazzitelli, G.; Stutman, D.; Soukanovskii, V.; Goldstein, W.H.

    1997-01-01

    For future fusion reactors, a careful balance must be achieved between the cooling of the outer plasma via impurity radiation and the deleterious effects of inevitable core penetration by impurity ions. We have injected krypton gas into the Frascati Tokamak Upgrade (FTU) plasma. The measured visible bremsstrahlung and bolometric signals from krypton have been inverted and the resulting radial impurity density profile and power loss profile for krypton gas are extracted. Using the measured electron density and temperature profiles, the radiative cooling coefficient for krypton is derived. The level of intrinsic impurities (Mo, Cr, Mn and Fe) in the plasma during the krypton puffing is monitored with a VUV SPRED spectrometer. Models for krypton emissivity from the literature are compared to our measured results. 7 figs

  12. Study on immobilization technology of krypton gas by ion-implantation and sputtering process

    International Nuclear Information System (INIS)

    Hayashi, S.; Kamiya, S.; Ikeda, S.; Nakanishi, Y.

    1997-01-01

    At the Waste Technology Development Division of PNC''s Tokai Works, we have been carrying out the development of the recovering and storing technology of radioactive krypton to reduce the radioactive gaseous effluent released to the environment arising from reprocessing of nuclear spent fuels. As a part of this technical development, the method of storing radioactive krypton is an encapsulation in a metal matrix which appears to offer the most secure immobilization of krypton. From the result of the ion-implantation test used non-radioactive krypton and the evaluation of electrical characteristics, we have selected the metallic materials, they are Nickel and Yttrium, and designed the vessel and the apparatus which continuously immobilized the krypton into metal matrix. This article described the following experiment result. (1) The long-term immobilization technology was established with respect to handling a equipment and plasma controlling. (2) Stability of the krypton immobilized alloy was considered satisfactory because the release was tolerably small. (author)

  13. Determination of low levels of krypton in helium by gas chromatography

    International Nuclear Information System (INIS)

    Evans, D.L.; Mukherji, A.K.

    1980-01-01

    Krypton-helium mixture was used as an adsorbate for surface area measurement--. The surface area measurements depend on the accuracy with which the krypton concentration is known. Generally gas tanks supplied by Union Carbide provide a nominal value of 0.1% krypton in helium. The surface area measurements require, however, that the krypton concentraion be known to +- 0.001% or better. A standard plot of krypton volume in microliters vs the area under the curve as measured by a planimeter using the helium detector and Molecular Sieve 5A column was obtained. Results with a thermal conductivity detector using Molecular Sieve 5A and Carbon Molecular Sieve are also given. Low levels of krypton in helium can be measured with precision using either a helium or a thermal conductivity detector with Molecular Sieve 5A or Carbon Molecular Sieve columns. 2 figures, 1 table

  14. Electronic structure of the actinides and their dioxides. Application to the defect formation energy and krypton solubility in uranium dioxide

    International Nuclear Information System (INIS)

    Petit, T.; CEA Centre d'Etudes de Grenoble, 38

    1996-01-01

    Uranium dioxide is the standard nuclear fuel used in French h power plants. During irradiation, fission products such as krypton and xenon are created inside fuel pellets. So, gas release could become, at very high burnup, a limiting factor in the reactor exploitation. To study this subject, we have realised calculations using the Density Functional Theory (DFT) into the Local Density Approximation (LDA) and the Atomic Sphere Approximation (ASA). First, we have validated our approach by calculating cohesive properties of thorium, protactinium and uranium metals. The good agreement between our results and experimental values implies that 5f electrons are itinerant. Calculated lattice parameter, cohesive energy and bulk modulus for uranium and thorium dioxides are in very good agreement with experiment. We show that binding between uranium and oxygen atoms is not completely ionic but partially covalent. The question of the electrical conductivity still remains an open problem. We have been able to calculate punctual defect formation energies in uranium dioxide. Accordingly to experimental observations, we find that it is easier to create a defect in the oxygen sublattice than in the uranium sublattice. Finally, we have been able to predict a probable site of krypton atoms in nuclear fuel: the Schottky trio. Experiences of Extended X-ray Absorption Fine structure Spectroscopy (EXAFS) and X-ray Photoelectron Spectroscopy (XPS) on uranium dioxide doped by ionic implantation will help us in the comprehension of the studied phenomena and the interpretation of our calculations. (author)

  15. Landfill Methane

    Science.gov (United States)

    Landfill methane (CH4) accounts for approximately 1.3% (0.6 Gt) of global anthropogenic greenhouse gas emissions relative to total emissions from all sectors of about 49 Gt CO2-eq yr-1. For countries with a history of controlled landfilling, landfills can be one of the larger national sources of ant...

  16. Evaluation of activated charcoal for dynamic adsorption of krypton and xenon

    International Nuclear Information System (INIS)

    Khan, A.A.; Deshingkar, D.S.; Ramarathinam, K.; Kishore, A.G.

    1975-01-01

    From the standpoint of radiation safety, the release of radioactive krypton and xenon from power reactors should be kept as low as practicable. The decay of shortlived isotopes of krypton and xenon by adsorptive delay on activated charcoal has shown promising results for this purpose. The delay provided by activated charcoal is proportional to the dynamic adsorption coefficients of these gases which are characteristic of the adsorbent. These coefficients were determined for krypton and xenon on indigenous gas-adsorbing activated charcoal at different moisture contents of carrier air stream and activated charcoal, concentrations of krypton around ambient temperatures, to find its suitability for designing adsorber columns. (author)

  17. Global characteristics of an ATON stationary plasma thruster operating with krypton and xenon

    International Nuclear Information System (INIS)

    Bugrova, A.I.; Lipatov, A.S.; Solomatina, L.V.; Morozov, A.I.

    2002-01-01

    Paper contains the experimental results of operation of the ATON plasma thruster operating with krypton and xenon. It is shown that consumption of a working gas for consumption of a working gas the krypton base thrust is higher in contrast to xenon base one at lower efficiency. In case of krypton use one obtained the efficiency constituting ∼ 60% at specific pulse reaching 3000 s. Jet divergence in case of krypton use is ∼ ± 22 deg in contrast to ∼ ± 11 deg in case of xenon use [ru

  18. Electron impact excitation of autoionising states of krypton

    Science.gov (United States)

    Srivastava, S. K.; Trajmar, S.

    1978-01-01

    Energy-loss spectra of krypton in the region between 21 and 29 eV have been obtained at electron impact energies of 30, 60 and 100 eV. For each energy, the angular distribution of intensities has been measured at 5, 10 and 15 deg scattering angles. Assignments of spectral features found in this region are suggested and a comparison is made with previous measurements.

  19. Transscleral contact krypton laser cyclophotocoagulation for treatment of posttraumatic glaucoma.

    Science.gov (United States)

    Raivio, V E; Immonen, I J; Laatikainen, L T; Puska, P M

    2001-04-01

    To evaluate the usefulness of the krypton laser for transscleral contact cyclophotocoagulation in the treatment of posttraumatic glaucoma. A total of 18 eyes of 18 patients with therapy-resistant posttraumatic glaucoma treated with krypton laser cyclophotocoagulation from 1991 to 1996 were included in this review. The krypton laser was delivered by a fiberoptic probe with simultaneous compression of the sclera. The energy used was 3 to 5 J per application at the tip of the probe, with an exposure time of 10 seconds. The treatment covered 90 to 360 degrees of the ciliary body with approximately 10 applications per quadrant. With one or more cyclophotocoagulation treatments, the intraocular pressure decreased from the baseline mean (+/- standard deviation) of 32.6 +/- 12.8 mm Hg to 23.6 +/- 10.3 mm Hg (n = 17) at 1 month, to 21.8 +/- 7.5 mm Hg (n = 13) at 3 months, to 22.5 +/- 7.6 mm Hg (n = 13) at 6 months, and to 19.6 +/- 10.5 mm Hg (n = 18) at the last control visit (mean, 19.4 months; range, 3 weeks to 73 months) after cyclophotocoagulation but no other glaucoma procedure. At baseline, 17 (94%) of 18 patients were taking glaucoma medication, as were 15 (83%) of 18 patients at the last control visit. One (6%) case of phthisis occurred. Krypton laser cyclophotocoagulation is an effective and reasonably well tolerated means of lowering intraocular pressure in posttraumatic glaucoma. Because of the refractory nature of the disease, repeated treatments may be needed.

  20. Design for a Remote Monitoring Equipment of Krypton-85

    Institute of Scientific and Technical Information of China (English)

    LUXue-sheng; LIUGuo-rong; YEFeng; JINHui-min; TANGPei-jia

    2003-01-01

    A prototype equipment for monitoring Krypton-85 in situ is designed and set up. A series of relevant software is also developed for remote control, data acquirement and data analysis. Weight of the system is about 300 kg, which is composed of NaI(T1) detector, digi DART, Marillin measurement container and lead shield. The whole system is placed on a homemade go-cart.

  1. Photocoagulation of disciform macular lesions with krypton laser.

    Science.gov (United States)

    Bird, A C; Grey, R H

    1979-01-01

    Ten vascular disciform mucular lesions were treated by krypton laser photocoagulation. In 8 the lesion resolved after therapy, and in 7 the retina remained flat for 6 months. On those patients treated successfully 6 had a visual acuity of 6/12 or better. The morphology of the laser lesion differed from that of the argon lesion in that there is no evidence of thermal coagulation of the inner retina near the foveola. Images PMID:574396

  2. Krypton isotope analysis using near-resonant stimulated Raman spectroscopy

    International Nuclear Information System (INIS)

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1994-12-01

    A method for measuring low relative abundances of 85 Kr in one liter or less samples of air has been under development here at Pacific Northwest Laboratory. The goal of the Krypton Isotope Laser Analysis (KILA) method is to measure ratios of 10 -10 or less of 85 Kr to more abundant stable krypton. Mass spectrometry and beta counting are the main competing technologies used in rare-gas trace analysis and are limited in application by such factors as sample size, counting times, and selectivity. The use of high-resolution lasers to probe hyperfine levels to determine isotopic abundance has received much attention recently. In this study, we report our progress on identifying and implementing techniques for trace 85 Kr analysis on small gas samples in a static cell as well as limitations on sensitivity and selectivity for the technique. High-resolution pulsed and cw lasers are employed in a laser-induced fluorescence technique that preserves the original sample. This technique, is based on resonant isotopic depletion spectroscopy (RIDS) in which one isotope is optically depleted while preserving the population of a less abundant isotope. The KILA method consists of three steps. In the first step, the 1s 5 metastable level of krypton is populated via radiative cascade following two-photon excitation of the 2p 6 energy level. Next, using RBDS, the stable krypton isotopes are optically depleted to the ground state through the 1s 4 level with the bulk of the 85 Kr population being preserved. Finally, the remaining metastable population is probed to determine 85 Kr concentration. The experimental requirements for each of these steps are outlined below

  3. Trapping of deuterium in krypton-implanted nickel

    International Nuclear Information System (INIS)

    Frank, R.C.; McManus, S.P.; Rehn, L.E.; Baldo, P.

    1986-01-01

    Krypton ions with energy 600 keV were implanted in nickel to fluences of 2 x 10 16 cm -2 under three different conditions. Deuterium was subsequently introduced into the implanted regions by electrolysis at room temperature. After the diffusible deuterium was permitted to escape, the 2 H( 3 He, 1 H) 4 He nuclear reaction was used to analyze for the trapped deuterium during an isochronal annealing program. The region implanted at 100 0 C with no higher temperature anneal had the largest number of traps; the region implanted at 100 0 C and annealed for 100 min at 500 0 C had considerably less; the region implanted at 500 0 C had the least. Electron diffraction patterns confirmed the existence of solid crystalline krypton in all three regions. Transmission electron microscope studies revealed precipitates with an average diameter of 8 nm in the region implanted at 500 0 C. The two regions implanted at 100 0 C contained smaller precipitates. Trap binding enthalpies were obtained by math modeling. In addition to the traps with binding enthalpy of 0.55 eV reported earlier by other investigators for helium implanted in nickel, a smaller number of traps with binding enthalpies up to 0.83 eV were also found. The trapping of deuterium by various types of imperfections, including the solid krypton precipitates, is discussed

  4. Krypton laser membranotomy in the treatment of dense premacular hemorrhage.

    Science.gov (United States)

    Chen, Yung-Jen; Kou, His-Kung

    2004-12-01

    Neodymium:YAG (Nd:YAG) laser and argon laser membranotomy have been used in patients with premacular hemorrhage to drain premacular blood into the vitreous cavity and rapidly clear the hemorrhage. However, the Nd:YAG laser appears to be difficult to use, and argon laser energy may be more likely to be absorbed by the ocular media. We performed a study to evaluate the safety and effectiveness of krypton laser membranotomy in selected cases of premacular hemorrhage. Sixteen patients (17 eyes) with dense premacular hemorrhage for 2 weeks or less were enrolled from April 1998 to February 2004. The causes of premacular hemorrhage were proliferative diabetic retinopathy (PDR) in 12 eyes, Valsalva retinopathy in 3 eyes, leukemia in I eye and retinal arterial macroaneurysm in I eye. Krypton laser was used to create a membranotomy on the sloping edge of the premacular hemorrhage. Five eyes with PDR were treated with inferior panretinal photocoagulation and laser membranotomy simultaneously. After intravitreal dispersion of premacular blood, fundus examination was performed in all eyes and fluorescein angiography in five eyes to evaluate retinal damage. All eyes had visual improvement within 2 weeks postoperatively. No retinal damage was seen at the site of membranotomy in any eye. No eye needed vitrectomy postoperatively during a mean follow-up duration of 18.6 months. Krypton laser membranotomy appears to be a safe and simple alternative procedure for treating selected cases of premacular hemorrhage. Further trials are necessary to evaluate its benefit.

  5. Separation, storage, and disposal of krypton-85: status and projects

    Energy Technology Data Exchange (ETDEWEB)

    Laser, M.

    1976-09-15

    Despite the relatively small impact of 85Kr to man the separation of fission krypton from the off-gas of fuel reprocessing plants must be taken into account. Combined with other advantages also in power reactor stations the retention of 85Kr seems to be attractive. Cryogenic processes are favored worldwide, because the technology has been well proven during several decades in air liquefaction and separation plants. Relatively small modifications must be made to adjust these processes to fission gas separation plants. Some fundamental data however are necessary for the design of a plant. Besides cryogenic processes a liquid adsorption for reprocessing off-gases and charcoal adsorption processes for reactor off-gas are under discussion. The retained krypton can be stored under air or water cooling in usual pressurized steel cylinders. However, legal problems may arise. The steel cylinders can be stored in engineered storage facilities for an intermediate period or finally. In Europe, however, the final storage will be questionable. Therefore, the dumping of 85Kr into the deep sea has been proposed. For this reason a revision of the London Convention is necessary, because the dumping of 85/Kr has not been specified. The IAEA as competent authority is asked to define the conditions for dumping. Injection of krypton containing gases into porous geologic strata may also be possible, if a very small release can be guaranteed.

  6. Build up of Radioactive Krypton and Xenon Analysis System

    International Nuclear Information System (INIS)

    Lee, D. K.; Choi, C. S.; Chung, K. H.; Lee, W.; Cho, Y. H.; Lee, C. W.

    2008-03-01

    The objective of this project is to build up an analysis system to measure the activity of the atmospheric radioactive krypton and xenon in Korea. The work scopes of the project include the purchase and the installation of the analysis system to measure the activity of the radioactive krypton and xenon in air, and the establishment of the operation capability of the system through the training of the operator. The system consists of two air sampling systems, and one radioactivity analysis system, which incorporates the enrichment system, the gas chromatography to purify a mixture gas, and the gas proportional counter to count the activity of pure krypton and xenon gas. As planned originally, the establishment of the analysis system has been completed. At present, one air sampler is successfully being operated at a specific site of the South Korea to measure the background radioactivities of Kr-85 and Xe-133 in air. The other air sampler is being reserved at the KAERI in the Daejeon for a emergency like the second nuclear test of the North Korea. During the normal time, the reserved air sampler will be used to collect the air sample for the performance test of the analysis system and the cross analysis for the calibration of the system. The radioactivity analysis system has been installed at the KAERI, and is being used to measure the activity of Kr-85 and Xe-133 in the air sample from a domestic site

  7. Krypton-85 and other airborne radioactivity measurements throughout Ireland

    International Nuclear Information System (INIS)

    Smith, K.J.; Murray, M.; Wong, J.; Sequeira, S.; Long, S.C.; Rafferty, B.

    2004-01-01

    In compliance with articles 35 and 36 of the EURATOM Treaty, the Radiological Protection Institute of Ireland (RPII) undertakes a comprehensive programme of radioactivity monitoring in the Irish terrestrial environment. Radioactivity is present in the terrestrial environment due to natural processes, the testing of nuclear weapons in the atmosphere, accidents such as the Chernobyl accident and the routine discharge of radionuclides from nuclear installations. The RPII monitors airborne radioactivity concentrations at ten stations throughout Ireland, of which, nine are equipped with low volume particulate samplers and one, in Dublin, with a high volume particulate sampler. The low volume particulate samples are assessed for total beta activity and high volume samples for gamma emitting radionuclides such as caesium-137 and beryllium-7. In addition, air sampled at the RPII laboratory in Dublin, is monitored for krypton-85, a radioactive noble gas, released into the environment primarily as a result of the reprocessing of nuclear fuel at installations such as Sellafield in the UK and La Hague in France. Since the inception of the krypton measurements in 1993 a trend of increasing atmospheric concentrations has been observed. The results of the krypton-85 monitoring, as well as the airborne radioactivity concentration measurements, will be presented and discussed in this paper. (author)

  8. Krypton-81 dating of old groundwater. Chapter 5

    International Nuclear Information System (INIS)

    Purtschert, R.; Yokochi, R.; Sturchio, N.C.

    2013-01-01

    The abundance of krypton in the atmosphere has been quoted for nearly half a century as 1.14 ± 0.01 ppm, which corresponds to a total atmospheric inventory of 4.51 × 10 12 m 3 STP (Verniani (1966) [243]). A recent re-evaluation yielded a value of 1.099 ± 0.009 ppmv, which is about 4% lower than the previously used value (Aoki and M akide (2005) [244]). Krypton has six stable isotopes of which 84 Kr is the most abundant, comprising about 57% of natural Kr (Table 5.1). Eleven major radioactive isotopes of Krexist but only 81 Kr and 85 Kr, with halflives of 229 000 and 10.76 a, respectively, exceed 2 d and are, therefore, suitable for the investigation of environmental processes. Krypton-81 is produced in the atmosphere by cosmic ray induced spallation of heavier stable Krisotopes and by the nuclear reactions 80 Kr(n, γ) 81 Kr and 82 Kr(γ, n) 81 Kr.

  9. Accurate ab initio potential for the krypton dimer and transport properties of the low-density krypton gas.

    Science.gov (United States)

    Waldrop, Jonathan M; Song, Bo; Patkowski, Konrad; Wang, Xiaopo

    2015-05-28

    A new highly accurate potential energy curve for the krypton dimer was constructed using coupled-cluster calculations up to the singles, doubles, triples, and perturbative quadruples level, including corrections for core-core and core-valence correlation and for relativistic effects. The ab initio data points were fitted to an analytic potential which was used to compute the most important transport properties of the krypton gas. The viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor were calculated by the kinetic theory at low density and temperatures from 116 to 5000 K. The comparisons with literature experimental data as well as with values from other pair potentials indicate that our new potential is superior to all previous ones. The transport property values computed in this work are recommended as standard values over the complete temperature range.

  10. Separation of the fission product noble gases krypton and xenon from dissolver off-gas in reprocessing HTGR-fuel

    International Nuclear Information System (INIS)

    Bohnenstingl, J.; Djoa, S.H.; Laser, M.; Mastera, S.; Merz, E.; Morschl, P.

    1976-01-01

    This paper describes a process developed for the retainment and separation of volatile ( 3 H, 129+131 I) and gaseous ( 85 Kr, Xe) fission products from the off-gas produced during dissolution of HTGR-fuel. To prevent unnecessary dilution of liberated noble gases by surrounding atmosphere, a helium purge-gas cycle is applied to enable a coarse fractionating of krypton and xenon by cold-trapping at about 80 0 K after precleaning the gas stream. The process consists of the following steps: deposition of droplets and solid aerosols; chemisorption of iodine on silver impregnated silica gel; catalytic removal of nitrogen oxides and oxygen; drying of the process gas stream; final filtering of abraded solids; deposition of xenon in solid form at 80 0 K and low subpressure; deposition of krypton in solid form at 80 0 K after compression to about 6 bar; decontamination of 85 Kr-containing xenon by batch distillation for eventual industrial utilization; and removal of nitrogen and argon enrichment during continuous operation in the purge-gas stream by inleaking air with charcoal. A continuously operating dissolver vessel, closed to the surrounding atmosphere, yields a very high content of noble gases, i.e., 0.35 vol % krypton and 2.0 vol % xenon. The presented off-gas treatment unit is operated in cold runs with 1 / 3 of the full capacity and can treat about 1 m 3 STP/h helium, corresponding to a quantity of about 10,000 MW/sub e/ HTGR-fuel reprocessing plant

  11. Widespread Methane Leakage from the Seafloor on the Northern US Atlantic Margin

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Methane emissions from the sea floor affect methane inputs into the atmosphere, ocean acidification and de-oxygenation, the distribution of chemosynthetic...

  12. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer such...

  13. THE RETENTION OF KRYPTON IN POLYCRYSTALLINE SILICON DURING HIGH-TEMPERATURE ANNEALING

    NARCIS (Netherlands)

    GREUTER, MJW; NIESEN, L; VANVEEN, A; EVANS, JH

    1994-01-01

    In a study into the annealing behaviour of silicon containing a few atomic per cent of krypton, it was found that, even at 0.87 of the silicon melting temperature, approximately 90% of the original krypton was still present. This result is compared with analogous work on metals where copious inert

  14. Relativistic Multichannel Treatment of Krypton Spectra across the First Ionization Threshold

    Institute of Scientific and Technical Information of China (English)

    QU Yi-Zhi; PENG Yong-Lun

    2005-01-01

    @@ The relativistic multichannel theory has been extended to calculate both the eigen quantum defects μα, transformation matrix Uiα, and the eigen dipole matrix elements Dα of krypton. The Rydberg and autoionizationspectra of krypton across the first ionization threshold are calculated within the framework of multichannel quantum defect theory. Our calculated spectra are in agreement with the absolute measurement data.

  15. Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant

    International Nuclear Information System (INIS)

    Linnell, Jesse A.; Gallimore, Alec D.

    2006-01-01

    For krypton to become a realistic option for Hall thruster operation, it is necessary to understand the performance gap between xenon and krypton and what can be done to reduce it. A floating emissive probe is used with the Plasmadynamics and Electric Propulsion Laboratory's High-speed Axial Reciprocating Probe system to map the internal plasma potential structure of the NASA-173Mv1 Hall thruster [R. R. Hofer, R. S. Jankovsky, and A. D. Gallimore, J. Propulsion Power 22, 721 (2006); and ibid.22, 732 (2006)] using xenon and krypton propellant. Measurements are taken for both propellants at discharge voltages of 500 and 600 V. Electron temperatures and electric fields are also reported. The acceleration zone and equipotential lines are found to be strongly linked to the magnetic-field lines. The electrostatic plasma lens of the NASA-173Mv1 Hall thruster strongly focuses the xenon ions toward the center of the discharge channel, whereas the krypton ions are defocused. Krypton is also found to have a longer acceleration zone than the xenon cases. These results explain the large beam divergence observed with krypton operation. Krypton and xenon have similar maximum electron temperatures and similar lengths of the high electron temperature zone, although the high electron temperature zone is located farther downstream in the krypton case

  16. Coalbed Methane Outreach Program

    Science.gov (United States)

    Coalbed Methane Outreach Program, voluntary program seeking to reduce methane emissions from coal mining activities. CMOP promotes profitable recovery/use of coal mine methane (CMM), addressing barriers to using CMM instead of emitting it to atmosphere.

  17. Contribution to the study of the structure of silver krypton solid solutions; Contribution a l'etude de la structure des solutions solides argent-krypton

    Energy Technology Data Exchange (ETDEWEB)

    Levy, V; Tullairet, J; Delaplace, J; Antolin-Baudier, J; Adda, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The silver-krypton solid solutions formed by electrical discharge have been studied by X-rays, electrical resistivity and electronic transmission microscopy. The crystalline parameter and residual resistivity measurements have shown that the krypton atom behaves very differently to those of other elements of the periodic classification when dissolved in silver. The recovery of the crystalline parameter and of the electrical resistivity has been studied as a function of temperature. (authors) [French] Les solutions solides argent, krypton, realisees par decharges electrique ont ete etudiees par Rayons X, resistivite electrique et microscopie electronique en transmission. Les mesures de parametre cristallin et de resistivite residuelle ont montre que le comportement de l'atome de krypton est tres different de celui des autres elements de la classification periodique en solution dans l'argent. La restauration du parametre cristallin et de la resistivite electrique en fonction de la temperature a ete etudiee. (auteurs)

  18. Krypton calibration of time projection chambers of the NA61/SHINE experiment

    CERN Document Server

    Naskret, Michal

    The NA61/SHINE experiment at CERN is searching for the critical point in phase transition between quark-gluon plasma and hadronic matter. To do so we use the most precise apparatus - Time Projection Chamber. Its main task is to find trajectories of particles created in a relativistic collision. In order to improve efficiency of TPCs, we introduce calibration using radioactive krypton gas. Simulation of events in a TPC cham- ber through a decay of excited krypton atoms gives us a spectrum, which is later fitted to the model spectrum of krypton from a Monte-Carlo simulation. The data obtained in such a way serves us to determine malfunctioning electronics in TPCs. Thanks to the krypton calibration we can create a map of pad by pad gains. In this thesis I will de- scribe in detail the NA61 experimental setup, krypton calibration procedure, calibration algorithm and results for recent calibration runs

  19. [Effect of krypton-containing gas mixture on Japanese quail embryo development].

    Science.gov (United States)

    Kussmaul', A R; Gur'eva, T S; Dadasheva, O A; Pavlov, N B; Pavlov, B N

    2008-01-01

    Investigated were effects of gas mixture with up to 3.0 kgs/cm2 of krypton on the embryonic development of domesticated Japanese quail (Coturnix coturnix japonica dom.). Results demonstrated absence of a serious krypton effect on Japanese quail embryos. Development of embryos proceeded in due course; morphometrically the experimental embryos were essentially similar to controls. It should be noted that despite exposure to acute hypoxic hypoxia during the initial 12 hours of development in the krypton-containing gas mixture, viability of quail embryos was high enough which can be ascribed to the krypton protective action. Besides, an additional experiment showed that krypton partial pressure of 5-5.5 kgs/cm2 produces the narcotic effect on adult Japanese quails.

  20. Ice crystal growth under the presence of krypton and methane at low temperature

    Science.gov (United States)

    Kawauchi, Taizo; Yoda, Yoshitaka; Fukutani, Katsuyuki

    2018-02-01

    To investigate the influence of foreign gas inclusion on the crystallization of ice, we studied the low-temperature (74 0.2) of Kr and CH4 enhance the formation of ice Ih and increase the crystal size, while at high foreign gas contents (R ⩽ 0.2) that may develop Kr or CH4 crystals below 92 K, the crystal size and relative amount of ice decrease strongly. The maximum ice Ih crystal size in the order of 200 nm was observed with either Kr or CH4 at 92 K for R = 0.2. We propose that Kr and CH4 induce the crystallization of ice by acting as a surfactant.

  1. Methane release

    International Nuclear Information System (INIS)

    Seifert, M.

    1999-01-01

    The Swiss Gas Industry has carried out a systematic, technical estimate of methane release from the complete supply chain from production to consumption for the years 1992/1993. The result of this survey provided a conservative value, amounting to 0.9% of the Swiss domestic output. A continuation of the study taking into account new findings with regard to emission factors and the effect of the climate is now available, which provides a value of 0.8% for the target year of 1996. These results show that the renovation of the network has brought about lower losses in the local gas supplies, particularly for the grey cast iron pipelines. (author)

  2. Monitoring of air pollutants and greenhouse gases. Monitoring Krypton-85

    International Nuclear Information System (INIS)

    Novitchkov, V.

    1996-01-01

    Krypton-85 is an anthropogenic radioactive noble gas, a gaseous fission product which builds up in the atmosphere. The World Meteorological Organization (WMO) Global Atmospheric Watch (GAW) integrates many monitoring and research activities involving the measurements of atmospheric composition. Kr-85 represents one of the gases recommended by the WMO for monitoring. The collaborative program of the Moscow State Engineering Physics Institute (MEPI) and the US Air Resources Laboratory (ARL) NOAA activities is aimed at determining the possible future consequences of Krypton-85 content (trend) increasing in the earth's atmosphere. The research is conducted at the MEPI to study the character of KR-85 release into the atmosphere and its distribution in the atmosphere, to determine Kr-85 possible sources. If only the question of the direct impact of Kr-85 on climate would be considered, only the order of magnitude of the atmospheric concentration would be of interest. In this case almost any available detection method and a precision as low as some 10% would be acceptable. If however, Kr-85 is to be applied as a tracer for the improvement of our present knowledge of local, regional and global transport and mixing processes and the validation of global-scale transport and mixing models, a much higher precision is required (order of +1%). This high standard cannot be met without a permanent quality assurance programmer. It is within the framework of the WMO that MEPI and the Air Resources Laboratory NOAA USA proposes collaboration of Kr-85 scientific findings. The project MEPI open-quotes Monitoring Krypton-85close quotes is being financed through the International Science and Technology Center

  3. Krypton gas cylinders as a source of radiation.

    Science.gov (United States)

    Fischer, Helmut W; Bielefeld, Tom; Hettwig, Bernd

    2010-07-01

    A standard 40 foot shipping container with a cargo of pressurized krypton gas in 159 steel cylinders, which had triggered a radiation alarm, was investigated to address radiation safety and illicit nuclear trafficking concerns. The investigation included contamination and dose rate measurements as well as in situ high resolution gamma spectroscopy. The dose rate measurements gave a maximum value of 0.07 microSv h(-1) above background (0.08 to 0.11 microSv h(-1)) on the cylinder surface and no detectable increase above background at distances of 1 m and higher. Contamination monitor readings showed a similar relative increase (plus 8 cpm) above background (about 12 cpm) to the dose rate readings. Quantitative gamma spectroscopy revealed a contamination of the gas with 85Kr at a level of 3.5 x 10(5) Bq kg(-1). This value was found to be consistent with analytical and numerical estimates based on current data for atmospheric 85Kr, which is captured from ambient air together with stable krypton during the production process. This incident demonstrates an apparent lack of radiation-related knowledge by those who handle krypton gas, as well as by border control personnel and emergency responders. We therefore propose to improve labeling and documentation standards for such shipments. This effort may be facilitated by introducing the new category of "technically enhanced artificial radioactive material," or "TEARM" (similar to the existing "naturally occurring radioactive material" or "NORM" and "technically enhanced naturally occurring radioactive material" or "TENORM" categories).

  4. Development of krypton-85 measurement in ocean samples by beta counting and use of the krypton-85 as a tracer in oceanography

    International Nuclear Information System (INIS)

    Ternon, Jean-Francois

    1990-01-01

    Krypton-85 present in the environment has essentially an anthropogenic origin, and the knowledge of the evolution of its concentration in the atmosphere, and of its mode of penetration in the ocean by gaseous exchange at the surface, and its bio-geochemical stability in the environment make it a potential tool to trace movements of water masses in the ocean. This research thesis aims at being a contribution to the implementation of an experimental device which would allow very low concentrations of krypton-85 in the ocean to be measured. After a presentation of the general context, the author reports the development of the two last steps of krypton-85 measurement: the separation of krypton by gas chromatography, and the measurement of krypton-85 by low-level radioactive counting. Then, the author reports the study of the use of krypton-85 as a tracer in oceanography, and notably highlights its similarities with CFC which are widely used to study ocean circulation [fr

  5. Biochemical composition and methane production correlations

    OpenAIRE

    Charnier, Cyrille; Latrille, Eric; Moscoviz, Roman; Miroux, Jérémie; Steyer, Jean-Philippe

    2016-01-01

    Substrates for anaerobic digestion are composed of heterogeneous and complex organic matter. General parameters of the organic matter can be used to describe its composition such as sugar, protein and lipid contents, Chemical Oxygen Demand (COD), Biochemical Methane Potential (BMP) and kinetic of methane production. These parameters are required for the monitoring of digesters but their characterization are time consuming and expensive; thus, these parameters are rarely assessed all together....

  6. Krypton-81m imaging of the right ventricle

    International Nuclear Information System (INIS)

    Horn, M.; Wiztum, K.; Neveu, C.; Perkins, G.; Walsh, B.

    1985-01-01

    The authors report the development of a method for obtaining right-ventricular radionuclide angiograms using continuous peripheral intravenous infusion of the ultra-short-lived nuclide krypton-81m. This tracer has a half-life of 13 sec, emits a single 190-keV photon, and is extremely insoluble. During infusion into a peripheral vein, Kr-81m achieves stable count rates over the right heart, and it is essentially completely cleared by the lungs during its initial pulmonary transit. Thus no interfering activity is present in the systemic circulation. Initial studies provide excellent data on right-heart anatomy and function

  7. Conceptual design of krypton recovery plant by porous membrane method

    International Nuclear Information System (INIS)

    Yoshida, Hiroshi; Fujine, Sachio; Shimizu, Toku; Saito, Keiichiro; Ouchi, Misao

    1979-10-01

    A conceptual design of a krypton recovery plant by porous membrane method was made to study feasibility of treating fuel reprocessing off-gas. Specifications of the plant could be clarified, such as off-gas pretreatment system, first cascade system of gaseous diffusion Hertz cascade composed of two-compartment diffusers, storage system, shield and housing and operating conditions. Capital costs and operating costs of the plant were estimated for different operating conditions and cost parameters. Technical and economic feasibility of the method compares favorably with those of the cryogenic distillation or the solvent absorption method. (author)

  8. Dealuminization treatment effect of krypton gas adsorption on zeolite

    International Nuclear Information System (INIS)

    Shin, J. M.; Shin, S. W.; Park, J. J.; Lee, H. H.; Yang, M. S.

    2003-01-01

    During the OREOX process of DUPIC fuel fabrication, krypton is released as a noble fission gas. In order to treat Kr safely, adsorption method on solids havs been selected. In order to determine the optimum extraction conditions of zeolite for Kr adsorption, the preliminary experiments for the concentration of hydrochloric acid were conducted. It was found that zeolite treated with 2N hydrochloric acid solution is superior to the zeolite untreated with HCl solution. When the zeolite was treated with 2N hydrochloric acid, it was found that the surface area was decreased. The micropores and the pore volume were increased and the adsorption amount of Kr gas was increased

  9. Melting line of Krypton in extreme thermodynamic regimes

    Directory of Open Access Journals (Sweden)

    Giuffre', E

    2007-01-01

    Full Text Available We have performed extensive computer simulations of the thermodynamic and structural properties of the krypton rare gas modeled by the modified Buckingham exponential-6 interatomic potential. Using a new set of potential parameters, we have found a good agreement with the room temperature equation of state at very high pressure obtained by diamond anvil cell experiments. Moreover, the melting line of the model has been estimated through the Lindemann criterion; the agreement with the low-pressure experiments is excellent, whereas at higher pressure, the model poorly reproduces the typical softening of the experimental melting curve.

  10. Cooling process in separation devices of krypton gas

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, S; Sugimoto, K

    1975-06-11

    To prevent entry of impurities into purified gases and to detect leaks of heat exchanger in a separation and recovering device of krypton gas by means of liquefaction and distillation, an intermediate refrigerant having the same or slightly higher boiling point than that of gas to be cooled is used between the gas to be cooled (process gas) and refrigerant (nitrogen), and the pressure of the gas to be cooled is controlled to have a pressure higher than the intermediate refrigerant to cool the gas to be cooled.

  11. The adsorption of argon, krypton and xenon on activated charcoal

    International Nuclear Information System (INIS)

    Underhill, D.W.

    1996-01-01

    Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs

  12. Removal of methane from compressed natural gas fueled vehicle exhaust

    International Nuclear Information System (INIS)

    Subramanian, S.; Kudla, R.J.; Chattha, M.S.

    1992-01-01

    The objective of this paper is to investigate the modes of methane (CH 4 ) removal from simulated compressed natural gas (CNG) fueled vehicle exhaust under net oxidizing, net reducing, and stoichiometric conditions. Model reaction studies were conducted. The results suggest that the oxidation of methane with oxygen contributes to the removal of methane under net oxidizing conditions. In contrast, the oxidation of methane with oxygen as well as nitric oxide contributes to its removal under net reducing conditions. The steam reforming reaction does not significantly contribute to the removal of methane. The methane conversions under net reducing conditions are higher than those observed under net oxidizing conditions. The study shows that the presence of carbon monoxide in the feed gas leads to a gradual decrease in the methane conversion with increasing redox ratio, under net oxidizing conditions. a minimum in methane conversion is observed at a redox ratio of 0. 8. The higher activity for the methane-oxygen reaction resulting from a lowering in the overall oxidation state of palladium and the contribution of the methane-nitric oxide reaction toward the removal of CH 4 appear to account for the higher CH 4 conversions observed under net reducing conditions

  13. Rain increases methane production and methane oxidation in a boreal thermokarst bog

    Science.gov (United States)

    Neumann, R. B.; Moorberg, C.; Turner, J.; Wong, A.; Waldrop, M. P.; Euskirchen, E. S.; Edgar, C.; Turetsky, M. R.

    2017-12-01

    Bottom-up biogeochemical models of wetland methane emissions simulate the response of methane production, oxidation and transport to wetland conditions and environmental forcings. One reason for mismatches between bottom-up and top-down estimates of emissions is incomplete knowledge of factors and processes that control microbial rates and methane transport. To advance mechanistic understanding of wetland methane emissions, we conducted a multi-year field investigation and plant manipulation experiment in a thermokarst bog located near Fairbanks, Alaska. The edge of the bog is experiencing active permafrost thaw, while the center of the bog thawed 50 to 100 years ago. Our study, which captured both an average year and two of the wettest years on record, revealed how rain interacts with vascular vegetation and recently thawed permafrost to affect methane emissions. In the floating bog, rain water warmed and oxygenated the subsurface, but did not alter soil saturation. The warmer peat temperatures increased both microbial methane production and plant productivity at the edge of the bog near the actively thawing margin, but minimally altered microbial and plant activity in the center of the bog. These responses indicate processes at the edge of the bog were temperature limited while those in the center were not. The compounding effect of increased microbial activity and plant productivity at the edge of the bog doubled methane emissions from treatments with vascular vegetation during rainy years. In contrast, methane emissions from vegetated treatments in the center of the bog did not change with rain. The oxygenating influence of rain facilitated greater methane oxidation in treatments without vascular vegetation, which offset warming-induced increases in methane production at the edge of the bog and decreased methane emissions in the center of the bog. These results elucidate the complex and spatially variable response of methane production and oxidation in

  14. Long-term storage of compressed radioactive krypton in cylinders

    International Nuclear Information System (INIS)

    Niephaus, D.; Nommensen, O.; Bruecher, H.

    1982-01-01

    The recommendations of the German Radiation Protection Commission necessitate the separation of the radioactive noble gas krypton-85 (Kr-85) produced in large LWR reprocessing plants from the dissolver off-gas. A possible method of removal is a long-term storage of the compressed noble gas above ground in cylinders. The aim of the present study is to develop such a storage concept and evaluate its feasibility under the aspects of safety and cost. After having been filled, the gas cylinders are placed separately into transport racks serving to protect the cylinders. Following this, the cylinders are transferred out of the filling station in a transport cask, conveyed to the storage building and stored there. The storage building protects the gas cylinders against external impacts. The storage cells constitute a second barrier against the release of Kr-85. The heat produced during decay of the Kr-85 in the gas cylinders is carried off by natural convection of the air circulating in the storage cells. To study possible corrosion attack on special steels due to rubidium, experiments were conducted at 200 0 C during test periods up to 3500h. In order to compare properties at elevated temperatures, corrosion experiments were conducted at 500 0 C, which is far above the maximum licensed storage temperature of 200 0 C. Experiments were conducted concerning the adsorption of krypton on various adsorbents, thus reducing the pressure inside the gas cylinder during storage. A cost estimate based on 1980 prices

  15. Experimental Investigations of a Krypton Stationary Plasma Thruster

    Directory of Open Access Journals (Sweden)

    A. I. Bugrova

    2013-01-01

    Full Text Available Stationary plasma thrusters are attractive electric propulsion systems for spacecrafts. The usual propellant is xenon. Among the other suggested propellants, krypton could be one of the best candidates. Most studies have been carried out with a Hall effect thruster previously designed for xenon. The ATON A-3 developed by MSTU MIREA (Moscow initially defined for xenon has been optimized for krypton. The stable high-performance ATON A-3 operation in Kr has been achieved after optimization of its magnetic field configuration and its optimization in different parameters: length and width of the channel, buffer volume dimensions, mode of the cathode operation, and input parameters. For a voltage of 400 V and the anode mass flow rate of 2.5 mg/s the anode efficiency reaches 60% and the specific impulse reaches 2900 s under A-3 operating with Kr. The achieved performances under operation A-3 with Kr are presented and compared with performances obtained with Xe.

  16. Supershort avalanche electron beam in SF6 and krypton

    Science.gov (United States)

    Zhang, Cheng; Tarasenko, Victor F.; Gu, Jianwei; Baksht, Evgeni Kh.; Beloplotov, Dmitry V.; Burachenko, Alexander G.; Yan, Ping; Lomaev, Mikhail I.; Shao, Tao

    2016-03-01

    Runaway electrons play an important role in the avalanche formation in nanosecond- and subnanosecond- pulse discharges. In this paper, characteristics of a supershort avalanche electron beam (SAEB) generated at the subnanosecond and nanosecond breakdown in sulfur hexafluoride (SF6 ) in an inhomogeneous electric field were studied. One pulser operated at negative polarity with voltage pulse amplitude of ˜130 kV and rise time of 0.3 ns. The other pulser operated at negative polarity with voltage pulse amplitude of 70 kV and rise time of ˜1.6 ns . SAEB parameters in SF6 are compared with those obtained in krypton (Kr), nitrogen (N2 ), air, and mixtures of SF6 with krypton or nitrogen. Experimental results showed that SAEB currents appeared during the rise-time of the voltage pulse for both pulsers. Moreover, amplitudes of the SAEB current in SF6 and Kr approximately ranged from several to tens of milliamps at atmospheric pressure, which were smaller than those in N2 and air (ranging from hundreds of milliamps to several amperes). Furthermore, the concentration of SF6 additive could significantly reduce the SAEB current in N2-SF6 mixture, but it slightly affected the SAEB current in Kr -SF6 mixture because of the atomic/molecular ionization cross section of the gas had a much greater impact on the SAEB current rather than the electronegativity.

  17. Theoretical investigation of the secondary ionization in krypton and xenon

    International Nuclear Information System (INIS)

    Saffo, M.E.

    1986-01-01

    A theoretical investigation of the secondary ionization processes that responsible for the pre-breakdown ionization current growth in a uniform electric field was studied in krypton and xenon gases, especially at low values of E/P 0 which is corresponding to high values of pressure, since there are a number of possible secondary ionization processes. It is interesting to carry out a quantitative analysis for the generalized secondary ionization coefficient obtained previously by many workers in terms of the production of excited states and their diffusion to the cathode and their destruction rate in the gas body. From energy balance equation for the electrons in the discharge, the fractional percentage energy losses of ionization, excitation, and elastic collisions to the total energy gained by the electron from the field has been calculated for krypton and xenon, as a result of such calculations; the conclusion drawn is that at low values of E/P 0 the main energy loss of electrons are in excited collision. Therefore, we are adopting a theoretical calculation for W/α under the assumption that the photo-electron emission at the cathode is the predominated secondary ionization process. 14 tabs.; 12 figs.; 64 refs

  18. Supershort avalanche electron beam in SF_{6} and krypton

    Directory of Open Access Journals (Sweden)

    Cheng Zhang (章程

    2016-03-01

    Full Text Available Runaway electrons play an important role in the avalanche formation in nanosecond- and subnanosecond- pulse discharges. In this paper, characteristics of a supershort avalanche electron beam (SAEB generated at the subnanosecond and nanosecond breakdown in sulfur hexafluoride (SF_{6} in an inhomogeneous electric field were studied. One pulser operated at negative polarity with voltage pulse amplitude of ∼130  kV and rise time of 0.3 ns. The other pulser operated at negative polarity with voltage pulse amplitude of 70 kV and rise time of ∼1.6  ns. SAEB parameters in SF_{6} are compared with those obtained in krypton (Kr, nitrogen (N_{2}, air, and mixtures of SF_{6} with krypton or nitrogen. Experimental results showed that SAEB currents appeared during the rise-time of the voltage pulse for both pulsers. Moreover, amplitudes of the SAEB current in SF_{6} and Kr approximately ranged from several to tens of milliamps at atmospheric pressure, which were smaller than those in N_{2} and air (ranging from hundreds of milliamps to several amperes. Furthermore, the concentration of SF_{6} additive could significantly reduce the SAEB current in N_{2}-SF_{6} mixture, but it slightly affected the SAEB current in Kr-SF_{6} mixture because of the atomic/molecular ionization cross section of the gas had a much greater impact on the SAEB current rather than the electronegativity.

  19. Particle simulation of grid system for krypton ion thrusters

    Directory of Open Access Journals (Sweden)

    Maolin CHEN

    2018-04-01

    Full Text Available The transport processes of plasmas in grid systems of krypton (Kr ion thrusters at different acceleration voltages were simulated with a 3D-PIC model, and the result was compared with xenon (Xe ion thrusters. The variation of the screen grid transparency, the accelerator grid current ratio and the divergence loss were explored. It is found that the screen grid transparency increases with the acceleration voltage and decreases with the beam current, while the accelerator grid current ratio and divergence loss decrease first and then increase with the beam current. This result is the same with Xe ion thrusters. Simulation results also show that Kr ion thrusters have more advantages than Xe ion thrusters, such as higher screen grid transparency, smaller accelerator grid current ratio, larger cut-off current threshold, and better divergence loss characteristic. These advantages mean that Kr ion thrusters have the ability of operating in a wide range of current. Through comprehensive analyses, it can be concluded that using Kr as propellant is very suitable for a multi-mode ion thruster design. Keywords: Grid system, Ion thrusters, Krypton, Particle in cell method, Plasma

  20. Interdiffusion of krypton and xenon in high-pressure helium

    International Nuclear Information System (INIS)

    Campana, R.J.; Jensen, D.D.; Epstein, B.D.; Hudson, R.G.; Baldwin, N.L.

    1980-01-01

    The interdiffusion of gaseous fission products in high-pressure helium is an important factor in the control of radioactivity in gas-cooled fast breeder reactors (GCFRs). As presently conceived, GCFRs use pressure-equalized and vented fuel in which fission gases released from the solid matrix oxide fuel are transported through the fuel rod interstices and internal fission product traps to the fuel assembly vents, where they are swept away to external traps and storage. Since the predominant transport process under steady-state operating conditions is interdiffusion of gaseous fission products in helium, the diffusion properties of krypton-helium and xenon-helium couples have been measured over the range of GCFR temperature and pressure conditions ( -1 ) and expected temperature dependence to the 1.66 power (Tsup(1.66)) at lower pressures and temperatures. Additional work is in progress to measure the behaviour of the krypton-helium and xenon-helium couples in GCFR fuel rod charcoal delay traps. (author)

  1. Krypton-85 hydrofracture engineering feasibility and safety evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Peretz, F.J.; Muller, M.E.; Pan, P.Y.

    1981-07-01

    Engineering studies have been made to determine the hazards associated with the disposal of /sup 85/Kr using the hydrofracture process. To assess the hazards, an effort has been made to identify the equipment required to entrain and dissolve the noble gas into the grout stream at hydrofracture pressure (up to 350 bar). Off-the-shelf or slightly modified equipment has been identified for safe and effective compression and gas-grout mixing. Each monthly injection disposes of 1.6 x 10/sup 6/ Ci of /sup 85/Kr. By connecting only one gas cylinder to the injection system at a time, the maximum amount of krypton likely to be released as a result of equipment failure is limited to 128,000 Ci. An evaluation by Los Alamos Technical Associates shows that releasing this amount of gas in less than one hour under worst-case meteorological conditions through a 30-m stack would result in a whole-body dose of 170 millirem at a distance of 1 km from the facility. A krypton collection and recovery system can further reduce this dose to 17 millirem; increasing the distance to the site boundary to 3 km can also reduce the dose by a factor of ten. Lung and skin dose estimates are 1.6 and 120 times the whole-body dose, respectively. These are all worst-case values; releases under more typical conditions would result in a significantly lower dose. No insurmountable safety or engineering problems have been identified.

  2. Krypton-85 hydrofracture engineering feasibility and safety evaluation

    International Nuclear Information System (INIS)

    Peretz, F.J.; Muller, M.E.; Pan, P.Y.

    1981-07-01

    Engineering studies have been made to determine the hazards associated with the disposal of 85 Kr using the hydrofracture process. To assess the hazards, an effort has been made to identify the equipment required to entrain and dissolve the noble gas into the grout stream at hydrofracture pressure (up to 350 bar). Off-the-shelf or slightly modified equipment has been identified for safe and effective compression and gas-grout mixing. Each monthly injection disposes of 1.6 x 10 6 Ci of 85 Kr. By connecting only one gas cylinder to the injection system at a time, the maximum amount of krypton likely to be released as a result of equipment failure is limited to 128,000 Ci. An evaluation by Los Alamos Technical Associates shows that releasing this amount of gas in less than one hour under worst-case meteorological conditions through a 30-m stack would result in a whole-body dose of 170 millirem at a distance of 1 km from the facility. A krypton collection and recovery system can further reduce this dose to 17 millirem; increasing the distance to the site boundary to 3 km can also reduce the dose by a factor of ten. Lung and skin dose estimates are 1.6 and 120 times the whole-body dose, respectively. These are all worst-case values; releases under more typical conditions would result in a significantly lower dose. No insurmountable safety or engineering problems have been identified

  3. Pulmonary ventilation imaging and function studies with krypton-81m

    International Nuclear Information System (INIS)

    Kaplan, E.; Mayron, L.W.; Gergans, G.A.; Friedman, A.M.; Gindler, J.E.

    1976-01-01

    Chronic obstructive lung disease is a significant entity throughout the world. It is etiologically related to smoking, air pollution and mining. To arrest asymptomatic disease, early diagnosis is required, implying an efficacious, reliable and available methodology, which has the potential for screening suspect populations. Krypton-81m is a 13-second radionuclide that emits a 190 keV gamma ray; it may be produced from a rubidium-81-krypton-81m generator and delivery system, devised, produced and evaluated by the authors. The generator effluent, in gaseous form, may be continually inhaled by a subject while static equilibrium images and dynamic studies of ventilation are produced with a gamma scintillation camera system. The wash-in of /sup 81m/Kr produces heterogeneous images, the activity being proportional to regional ventilation due to rapid decay. Minimal ventilatory delays are detectable. Normal subjects and patients with obstructive lung disease have been evaluated by static equilibrium and dynamic studies. The sensitivity of /sup 81m/Kr studies is currently being compared with various other pulmonary function tests, to evaluate its potential as an appropriate screening technique

  4. Search for interstellar methane

    International Nuclear Information System (INIS)

    Knacke, R.F.; Kim, Y.H.; Noll, K.S.; Geballe, T.R.

    1990-01-01

    Researchers searched for interstellar methane in the spectra of infrared sources embedded in molecular clouds. New observations of several lines of the P and R branches of the nu 3 band of CH4 near 3.3 microns give column densities in the range N less than 1(-2) times 10 to the minus 16th power cm(-2). Resulting abundance ratios are (CH4)/(CO) less than 3.3 times 10 to the minus 2nd power toward GL961 in NGC 2244 and less than 2.4 times 10 to the minus 3rd power toward GL989 in the NGC 2264 molecular cloud. The limits, and those determined in earlier observations of BN in Orion and GL490, suggest that there is little methane in molecular clouds. The result agrees with predictions of chemical models. Exceptions could occur in clouds where oxygen may be depleted, for example by H2O freezing on grains. The present observations probably did not sample such regions

  5. Temporal variation of aerobic methane oxidation over a tidal cycle in a wetland of northern Taiwan.

    Science.gov (United States)

    Lee, T. Y.; Wang, P. L.; Lin, L. H.

    2017-12-01

    Aerobic methanotrophy plays an important role in controlling methane emitted from wetlands. However, the activity of aerobic methanotrophy regulated by temporal fluctuation of oxygen and methane supply in tidal wetlands is not well known. This study aims to examine the dynamics of methane fluxes and potential aerobic methane consumption rates in a tidal wetland of northern Taiwan, where the variation of environmental characteristics, such as sulfate and methane concentration in pore water has been demonstrated during a tidal cycle. Two field campaigns were carried out in December of 2016 and March of 2017. Fluxes of methane emission, methane concentrations in surface sediments and oxygen profiles were measured at different tidal phases. Besides, batch incubations were conducted on surface sediments in order to quantify potential microbial methane consumption rates and to derive the kinetic parameters for aerobic methanotrophy. Our results demonstrated temporal changes of the surface methane concentration and the methane emission flux during a tidal cycle, while the oxygen flux into the sediment was kept at a similar magnitude. The methane flux was low when the surface was exposed for both shortest and longest periods of time. The potential aerobic methane oxidation rate was high for sample collected from the surface sediments exposed the longest. No correlation could be found between the potential aerobic methane oxidation rate and either the oxygen downward flux or methane emission flux. The decoupled relationships between these observed rates and fluxes suggest that, rather than aerobic methanotrophy, heterotrophic respirations exert a profound control on oxygen flux, and the methane emission is not only been affected by methane consumption but also methane production at depths. The maximum potential rate and the half saturation concentration determined from the batch incubations were high for the surface sediments collected in low tide, suggesting that aerobic

  6. On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Schmitt

    2013-05-01

    Full Text Available Stable carbon isotope analysis of methane (δ13C of CH4 on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography (GC isotope ratio mass spectrometry (IRMS coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton (Kr can severely interfere during the mass spectrometric measurement, leading to significant biases in δ13C of CH4, if krypton is not sufficiently separated during the analysis. According to our experiments, the krypton interference is likely composed of two individual effects, with the lateral tailing of the doubly charged 86Kr peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups. Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to result from scattered ions of singly charged krypton. The introduced bias in the measured isotope ratios is dependent on the chromatographic separation, the krypton-to-CH4 mixing ratio in the sample, the focusing of the mass spectrometer as well as the detector configuration and can amount to up to several per mil in δ13C. Apart from technical solutions to avoid this interference, we present correction routines to a posteriori remove the bias.

  7. Radiometric titration of officinal radiopharmaceuticals using radioactive kryptonates as end-point indicators. I

    International Nuclear Information System (INIS)

    Toelgyessy, J.; Dillinger, P.; Harangozo, M.; Jombik, J.

    1980-01-01

    A method for the determination of salicylic, acetylsalicylic and benzoic acids in officinal pharmaceutical based on radiometric titration with 0.1 mol.l -1 NaOH was developed. The end-point was detected with the aid of radioactive glass kryptonate. After the end-point, the excess titrant attacks the glass surface layers and this results in releasing 85 Kr, and consequently, in decreasing the radioactivity of the kryptonate employed. The radioactive kryptonate used as an indicator was prepared by the bombardment of glass with accelerated 85 Kr ions. The developed method is simple, accurate and correct. (author)

  8. The mutual influence of krypton implantation and pre-existing stress states in polycrystalline alpha titanium

    Energy Technology Data Exchange (ETDEWEB)

    Nsengiyumva, S. [Department of Physics, University of Cape Town, Rondebosch 7701 (South Africa); Department of Physics, Kigali Institute of Education, P.O. Box 5039 Kigali (Rwanda)], E-mail: schadrack.nsengiyumva@uct.ac.za; Ntsoane, T.P. [Nuclear Energy Corporation of South Africa (NECSA), P.O. Box 582 (South Africa); Raji, A.T. [Department of Physics, University of Cape Town, Rondebosch 7701 (South Africa); Topic, M. [iThemba LABS, Somerset West 7129 (South Africa); Kellermann, G. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas (Brazil); Riviere, J.P. [Laboratoire de Physique des Materiaux UMR6630-CNRS, 86960 (France); Britton, D.T.; Haerting, M. [Department of Physics, University of Cape Town, Rondebosch 7701 (South Africa)

    2009-08-15

    The stress profile in polycrystalline titanium implanted with krypton ions at different fluences has been determined using synchrotron radiation diffraction. For each fluence, the krypton profile has been measured using Rutherford backscattering geometry. The results were compared to model calculations obtained from the SRIM 2008 computer code. A strong stress relaxation was found for high fluence implantation, whereas for low fluence implantation an additional source of tensile stress was introduced in the near surface region. The projected range of the implanted krypton was significantly reduced compared to the expected range. A possible cause of this discrepancy is the drift of implanted ions under the influence of the pre-existing stress gradient.

  9. The mutual influence of krypton implantation and pre-existing stress states in polycrystalline alpha titanium

    International Nuclear Information System (INIS)

    Nsengiyumva, S.; Ntsoane, T.P.; Raji, A.T.; Topic, M.; Kellermann, G.; Riviere, J.P.; Britton, D.T.; Haerting, M.

    2009-01-01

    The stress profile in polycrystalline titanium implanted with krypton ions at different fluences has been determined using synchrotron radiation diffraction. For each fluence, the krypton profile has been measured using Rutherford backscattering geometry. The results were compared to model calculations obtained from the SRIM 2008 computer code. A strong stress relaxation was found for high fluence implantation, whereas for low fluence implantation an additional source of tensile stress was introduced in the near surface region. The projected range of the implanted krypton was significantly reduced compared to the expected range. A possible cause of this discrepancy is the drift of implanted ions under the influence of the pre-existing stress gradient.

  10. Effects of pulmonary inhalation on hyperpolarized krypton-83 magnetic resonance T1 relaxation.

    Science.gov (United States)

    Stupic, K F; Elkins, N D; Pavlovskaya, G E; Repine, J E; Meersmann, T

    2011-07-07

    The (83)Kr magnetic resonance (MR) relaxation time T(1) of krypton gas in contact with model surfaces was previously found to be highly sensitive to surface composition, surface-to-volume ratio, and surface temperature. The work presented here explored aspects of pulmonary (83)Kr T(1) relaxation measurements in excised lungs from healthy rats using hyperpolarized (hp) (83)Kr with approximately 4.4% spin polarization. MR spectroscopy without spatial resolution was applied to the ex vivo lungs that actively inhale hp (83)Kr through a custom designed ventilation system. Various inhalation schemes were devised to study the influence of anatomical dead space upon the measured (83)Kr T(1) relaxation times. The longitudinal (83)Kr relaxation times in the distal airways and the respiratory zones were independent of the lung inhalation volume, with T(1) = 1.3 s and T(1) = 1.0 s, depending only on the applied inhalation scheme. The obtained data were highly reproducible between different specimens. Further, the (83)Kr T(1) relaxation times in excised lungs were unaffected by the presence of up to 40% oxygen in the hp gas mixture. The results support the possible importance of (83)Kr as a biomarker for evaluating lung function.

  11. Crenothrix are major methane consumers in stratified lakes.

    Science.gov (United States)

    Oswald, Kirsten; Graf, Jon S; Littmann, Sten; Tienken, Daniela; Brand, Andreas; Wehrli, Bernhard; Albertsen, Mads; Daims, Holger; Wagner, Michael; Kuypers, Marcel Mm; Schubert, Carsten J; Milucka, Jana

    2017-09-01

    Methane-oxidizing bacteria represent a major biological sink for methane and are thus Earth's natural protection against this potent greenhouse gas. Here we show that in two stratified freshwater lakes a substantial part of upward-diffusing methane was oxidized by filamentous gamma-proteobacteria related to Crenothrix polyspora. These filamentous bacteria have been known as contaminants of drinking water supplies since 1870, but their role in the environmental methane removal has remained unclear. While oxidizing methane, these organisms were assigned an 'unusual' methane monooxygenase (MMO), which was only distantly related to 'classical' MMO of gamma-proteobacterial methanotrophs. We now correct this assignment and show that Crenothrix encode a typical gamma-proteobacterial PmoA. Stable isotope labeling in combination swith single-cell imaging mass spectrometry revealed methane-dependent growth of the lacustrine Crenothrix with oxygen as well as under oxygen-deficient conditions. Crenothrix genomes encoded pathways for the respiration of oxygen as well as for the reduction of nitrate to N 2 O. The observed abundance and planktonic growth of Crenothrix suggest that these methanotrophs can act as a relevant biological sink for methane in stratified lakes and should be considered in the context of environmental removal of methane.

  12. Methane emission by adult ostriches (Struthio camelus).

    Science.gov (United States)

    Frei, Samuel; Dittmann, Marie T; Reutlinger, Christoph; Ortmann, Sylvia; Hatt, Jean-Michel; Kreuzer, Michael; Clauss, Marcus

    2015-02-01

    Ostriches (Struthio camelus) are herbivorous birds with a digestive physiology that shares several similarities with that of herbivorous mammals. Previous reports, however, claimed a very low methane emission from ostriches, which would be clearly different from mammals. If this could be confirmed, ostrich meat would represent a very attractive alternative to ruminant-and generally mammalian-meat by representing a particularly low-emission agricultural form of production. We individually measured, by chamber respirometry, the amount of oxygen consumed as well as carbon dioxide and methane emitted from six adult ostriches (body mass 108.3±8.3 kg) during a 24-hour period when fed a pelleted lucerne diet. While oxygen consumption was in the range of values previously reported for ostriches, supporting the validity of our experimental setup, methane production was, at 17.5±3.2 L d(-1), much higher than previously reported for this species, and was of the magnitude expected for similar-sized, nonruminant mammalian herbivores. These results suggest that methane emission is similar between ostriches and nonruminant mammalian herbivores and that the environmental burden of these animals is comparable. The findings furthermore indicate that it appears justified to use currently available scaling equations for methane production of nonruminant mammals in paleo-reconstructions of methane production of herbivorous dinosaurs. Copyright © 2014. Published by Elsevier Inc.

  13. LOX/Methane Regeneratively-Cooled Rocket Engine Development

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this project is to advance the technologies required to build a subcritical regeneratively cooled liquid oxygen/methane rocket combustion chamber for...

  14. Optimization of krypton yields for rp-process studies at ISOLDE (CERN)

    CERN Document Server

    Kankainen, Anu Kristiina; Fraile-Prieto, L M; Jokinen, A; Leitner, M S; Oinonen, M; Peräjärvi, K; Ravn, H L

    2004-01-01

    The production of neutron-deficient krypton isotopes having astrophysical importance has been studied at the ISOLDE PBS facility at CERN. To investigate several effects on the yield a Monte Carlo code has been extensively applied.

  15. A review of ''The potential effects of release of krypton-85''

    International Nuclear Information System (INIS)

    Saunders, C.P.R.

    1993-06-01

    A Report into the potential effects of the release of Krypton-85 from the Thermal Oxide Reprocessing Plant (THORP) at Sellafield, was commissioned by British Nuclear Fuels Ltd. The report dealt with the atmospheric impact of the release of Krypton-85 and considered specifically the areas of atmospheric electricity, ionisation, aerosols and conductivity, in terms of the releases of Krypton-85 from THORP. This present review has three objectives: to consider the atmospheric effects of the proposed discharges from THORP, to comment upon the magnitude of the postulated effects from Krypton-85 discharges compared with those from other sources of radioactivity in the atmosphere, and, to comment on the conclusions drawn by the authors of the report. This review was conducted under the aegis of the United Kingdom Inspectorate of Pollution. (author)

  16. Operation and technology development of the radioactive xenon and krypton detection equipment

    International Nuclear Information System (INIS)

    Lee, Wanno; Choi, Sangdo; Ji, Youngyong; Lim, Jong Myoung; Cho, Young Hyun; Kang, Han Beul; Lee, Hoon; Kang, Moon Ja; Choi, Kun Sik

    2013-03-01

    Operation and technology development of the radioactive xenon and krypton detection equipment - Advancement, independence of operation technology for BfS-IAR system(the simultaneous analysis of xenon and krypton) installed after North Korea nuclear tests in 2006 and establishment of background base-line for xenon and krypton radioactivity. - Enhanced detection and analysis capabilities for neighborhood nuclear activities through advanced research of noble gas detection technology. Results of the Project · The operation of xenon and krypton analysis system (BfS-IAR) · Operation of fixed adsorption system. · Operation of portable adsorption system · Exercise of emergency response and proficiency test with SAUNA. · Measurement of noble gas background at specific region in Korea. - Radioxenon levels at Dongdu Cheon is approximately 1.6 mBq/m 3 · Development of automation filling system for absorber cooling

  17. Spin asymmetries for elastic scattering in krypton at intermediate energies

    International Nuclear Information System (INIS)

    Went, M R; McEachran, R P; Lohmann, Birgit; MacGillivray, W R

    2002-01-01

    Measurements of the spin asymmetry for elastic scattering of spin-polarized electrons from krypton are presented, for incident energies in the range 20-200 eV. The measured spin asymmetries are generally small, and do not exceed 0.25 in magnitude at any energy or angle. The experimental results are compared with calculated values of the Sherman function, obtained by solution of the Dirac-Fock equations. The calculations have been performed with the inclusion of polarization and dynamic distortion potentials, and with the addition of an absorption potential to model inelastic processes. For incident energies of 50, 60 and 65 eV, the calculated values of the Sherman function are shown to be extremely sensitive to the details of the model, with the addition of the absorption potential producing dramatically different results

  18. Two-photon resonant, stimulated processes in krypton and xenon

    International Nuclear Information System (INIS)

    Miller, J.C.

    1988-11-01

    Both on-axis and conical emissions have been observed following two-photon pumping of the 5p states of krypton and the 6p', 7p, 8p, and 4f states of xenon. In the former case, coherent emissions from the 5p states to the 5s are observed, and in the latter case, many p→s, d→p, and f→d cascade emissions are observed. By analogy to the well-studied alkali and alkaline earth examples, the emissions are discussed in terms of amplified spontaneous emission (ASE), stimulated hyper-Raman scattering, and parametric four-wave mixing. The physical processes responsible for the conical emission and for intensity anomalies in the xenon p→s emissions are not understood at present. Interference effects due to coherent cancellation between competing excitation pathways may be occurring. 4 refs., 3 figs

  19. The evaluation of right ventricular performance using krypton-81m

    International Nuclear Information System (INIS)

    Ham, H.R.; Piepsz, A.; Vandevivere, J.; Guillaume, M.; Goethals, P.; Lenaers, A.

    1983-01-01

    The availability of krypton-81m suitable for intravenous injection provides an easy means for assessing right ventricular function. The superimposition of the other heart chambers does not constitute a problem. The activity in the left heart is negligible and the study can be performed in the right anterior oblique position to obtain optimal separation between the right atrium and the right ventricle. Lung activity is quite high and should be corrected before computing the right ventricular ejection fraction. This correction can be accomplished by performing Tc-99m MAA perfusion scintigraphy. The measurement of the right ventricular ejection fraction appears to be reproducible with very small inter-and intraobserver variability. Good quality phase and amplitude images can be obtained with such high count rates

  20. Ultrafast quantum control of ionization dynamics in krypton.

    Science.gov (United States)

    Hütten, Konrad; Mittermair, Michael; Stock, Sebastian O; Beerwerth, Randolf; Shirvanyan, Vahe; Riemensberger, Johann; Duensing, Andreas; Heider, Rupert; Wagner, Martin S; Guggenmos, Alexander; Fritzsche, Stephan; Kabachnik, Nikolay M; Kienberger, Reinhard; Bernhardt, Birgitta

    2018-02-19

    Ultrafast spectroscopy with attosecond resolution has enabled the real time observation of ultrafast electron dynamics in atoms, molecules and solids. These experiments employ attosecond pulses or pulse trains and explore dynamical processes in a pump-probe scheme that is selectively sensitive to electronic state of matter via photoelectron or XUV absorption spectroscopy or that includes changes of the ionic state detected via photo-ion mass spectrometry. Here, we demonstrate how the implementation of combined photo-ion and absorption spectroscopy with attosecond resolution enables tracking the complex multidimensional excitation and decay cascade of an Auger auto-ionization process of a few femtoseconds in highly excited krypton. In tandem with theory, our study reveals the role of intermediate electronic states in the formation of multiply charged ions. Amplitude tuning of a dressing laser field addresses different groups of decay channels and allows exerting temporal and quantitative control over the ionization dynamics in rare gas atoms.

  1. The NA62 Liquid Krypton calorimeter data acquisition upgrade

    CERN Document Server

    Hallgren, Bjorn; Piccini, Mauro; Wendler, Helmut; 10.1109/NSSMIC.2008.4774802

    2009-01-01

    The NA62 experiment at CERN, aiming to start data taking in 2011, intends to measure the branching ratio of extremely rare kaon decays. The existing Liquid Krypton (LKr) calorimeter of the NA48 experiment will play an essential role in the new experiment. For this reason a program for the consolidation of the LKr read-out system was launched in 2006. The first part of the program consists of updating the existing data acquisition system to a modern more reliable technology using Gigabit Ethernet and PC-farm. In the second stage the readout event rate has to be increased from 13 kHz to 1 MHz. Methods to do this, while keeping much of the existing analog system, are discussed.

  2. Incineration of oxygenated volatile organic compounds. Experimental study and kinetic modeling of the oxidation of methyl ethyl ketone, ethyl acetate and butan-2-ol in methane flames; Incineration de composes organiques volatils oxygenes. Etude experimentale et modelisation cinetique de l'oxydation de la methyl ethyl cetone, de l'acetate d'ethyle et du butan-2-ol dans des flammes de methane

    Energy Technology Data Exchange (ETDEWEB)

    Decottignies, V.

    2000-12-01

    This work deals with the low pressure (0.05 atm) degradation of three volatile organic compounds (VOCs): methyl-ethyl-ketone, ethyl acetate and butan-2-ol, in premixed stoichiometric laminar methane flames seeded with 1 to 3% of each VOC. Molar fraction profiles of species have been obtained using microprobe sampling coupled with a gas chromatography and a mass spectroscopy analysis. Temperature profiles have been obtained using the covered thermocouple technique in the presence of the microprobe. The addition of a VOC in the initial reagents mixture leads to an increase of the quantity of intermediate hydrocarbon compounds and in particular of some soot precursor species. The degradation of VOCs leads to the formation of oxygenated intermediates like methanol, dimethyl-ether, acetaldehyde, propanal, acetone and vinyl acetate, the type of VOC having an effect on the quantities produced. The degradation of a VOC can lead to the formation of more toxic or polluting compounds (methyl vinyl ketone, acetic acid and acrolein) than the VOC itself. In the conditions of the study, the intermediate compounds are totally destructed inside the reactional area of the flame front and are no more present in the burnt gases. Sub-mechanisms of VOC oxidation have been developed using experimental observations and the most recent recommendations of the literature. These sub-mechanisms comprise 49 species involved in 241 elementary reactions. Their validation has been performed by comparing the experiment with the kinetic modeling on the molar fraction profiles of the detected species. Experimental data are well reproduced by the model for most species. The addition of a VOC inside the initial reagents mixture creates an important reactivity increase, in particular in the case of butan-2-ol seeded flames. The analysis of reactional ways has permitted to draw out the main reactions responsible for the degradation of the 3 VOCs and the ways of formation and consumption of the

  3. Auger measurements on the two-dimensional adsorption of krypton on graphite

    International Nuclear Information System (INIS)

    Kramer, H.M.; Suzanne, J.

    1975-01-01

    The adsorption of krypton on a (0001) plane of graphite was studied by means of Auger Electron Spectroscopy. The spectrum of krypton in the energy range from 5eV to 11eV and from 30eV to 70eV is reported. By means of LEED a √3x√3 superstructure is found for the adsorbed monolayer of Kr [fr

  4. Radiometric titration of officinal radiopharmaceuticals using radioactive kryptonates as end-point indicators. II

    International Nuclear Information System (INIS)

    Harangozo, M.; Jombik, J.; Schiller, P.; Toelgyessy, J.

    1981-01-01

    A method for the determination of citric, tartaric and undecylenic acids based on radiometric titration with 0.1 or 0.05 mole.l -1 NaOH was developed. As an indicator of the end point, radioactive kryptonate of glass was used. Experimental technique, results of determinations as well as other possible applications of the radioactive kryptonate of glass for end point determination in alkalimetric analyses of officinal pharmaceuticals are discussed. (author)

  5. Contribution to the study of the structure of silver krypton solid solutions

    International Nuclear Information System (INIS)

    Levy, V.; Tullairet, J.; Delaplace, J.; Antolin-Baudier, J.; Adda, Y.

    1964-01-01

    The silver-krypton solid solutions formed by electrical discharge have been studied by X-rays, electrical resistivity and electronic transmission microscopy. The crystalline parameter and residual resistivity measurements have shown that the krypton atom behaves very differently to those of other elements of the periodic classification when dissolved in silver. The recovery of the crystalline parameter and of the electrical resistivity has been studied as a function of temperature. (authors) [fr

  6. The place of krypton-81m ventilation in the scintigraphic investigation of the lung

    International Nuclear Information System (INIS)

    Hoefnagel, C.A.; Marcuse, H.R.

    1983-01-01

    Fairly recently krypton-81m gas became available for diagnostic purposes. Its advantages and ways to use are surveyed especially for the diagnosis of lung emboli and lung diseases. The combination of perfusion and ventilation scintigrams is the best for specifying the diagnosis. Krypton-81m gas improves the specificity and sensitivity of the examination which is non-invasive and carries no burden for the patient. (Auth.)

  7. Status of the NA62 liquid krypton electromagnetic calorimeter Level 0 trigger processor

    CERN Document Server

    Bonaiuto, V; Fucci, A; Paoluzzi, G; Salamon, A; Salina, G; Santovetti, E; Sargeni, F; Venditti, S

    2013-01-01

    The NA62 experiment at the CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K(+)→π(+)νbar nu collecting O(100) events with a 10% background in two years of data taking. To reject the K(+)→π(+)π(0) background the NA48 liquid krypton calorimeter will be used in the 1-10 mrad angular region. The status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger is presented.

  8. Determination of Krypton Diffusion Coefficients in Uranium Dioxide Using Atomic Scale Calculations.

    Science.gov (United States)

    Vathonne, Emerson; Andersson, David A; Freyss, Michel; Perriot, Romain; Cooper, Michael W D; Stanek, Christopher R; Bertolus, Marjorie

    2017-01-03

    We present a study of the diffusion of krypton in UO 2 using atomic scale calculations combined with diffusion models adapted to the system studied. The migration barriers of the elementary mechanisms for interstitial or vacancy assisted migration are calculated in the DFT+U framework using the nudged elastic band method. The attempt frequencies are obtained from the phonon modes of the defect at the initial and saddle points using empirical potential methods. The diffusion coefficients of Kr in UO 2 are then calculated by combining this data with diffusion models accounting for the concentration of vacancies and the interaction of vacancies with Kr atoms. We determined the preferred mechanism for Kr migration and the corresponding diffusion coefficient as a function of the oxygen chemical potential μ O or nonstoichiometry. For very hypostoichiometric (or U-rich) conditions, the most favorable mechanism is interstitial migration. For hypostoichiometric UO 2 , migration is assisted by the bound Schottky defect and the charged uranium vacancy, V U 4- . Around stoichiometry, migration assisted by the charged uranium-oxygen divacancy (V UO 2- ) and V U 4- is the favored mechanism. Finally, for hyperstoichiometric or O-rich conditions, the migration assisted by two V U 4- dominates. Kr migration is enhanced at higher μ O , and in this regime, the activation energy will be between 4.09 and 0.73 eV depending on nonstoichiometry. The experimental values available are in the latter interval. Since it is very probable that these values were obtained for at least slightly hyperstoichiometric samples, our activation energies are consistent with the experimental data, even if further experiments with precisely controlled stoichiometry are needed to confirm these results. The mechanisms and trends with nonstoichiometry established for Kr are similar to those found in previous studies of Xe.

  9. Could Methane Oxidation in Lakes Be Enhanced by Eutrophication?

    Science.gov (United States)

    Van Grinsven, S.; Villanueva, L.; Harrison, J.; S Sinninghe Damsté, J.

    2017-12-01

    Climate change and eutrophication both affect aquatic ecosystems. Eutrophication is caused by high nutrient inputs, leading to algal blooms, oxygen depletion and disturbances of the natural balances in aquatic systems. Methane, a potent greenhouse gas produced biologically by anaerobic degradation of organic matter, is often released from the sediments of lakes and marine systems to overlying water and the atmosphere. Methane oxidation, a microbial methane consumption process, can limit methane emission from lakes and reservoirs by 50-80%. Here, we studied methane oxidation in a seasonally stratified reservoir: Lacamas Lake in Washington, USA. We found this lake has a large summer storage capacity of methane in its deep water layer, with a very active microbial community capable of oxidizing exceptionally high amounts of methane. The natural presence of terminal electron acceptors is, however, too low to support these high potential rates. Addition of eutrophication-related nutrients such as nitrate and sulfate increased the methane removal rates by 4 to 7-fold. The microbial community was studied using 16S rRNA gene amplicon sequencing and preliminary results indicate the presence of a relatively unknown facultative anaerobic methane oxidizer of the genus Methylomonas, capable of using nitrate as an electron donor. Experiments in which anoxic and oxic conditions were rapidly interchanged showed this facultative anaerobic methane oxidizer has an impressive flexibility towards large, rapid changes in environmental conditions and this feature might be key to the unexpectedly high methane removal rates in eutrophied and anoxic watersheds.

  10. Using zeolites for fixation and long-term storage of krypton

    International Nuclear Information System (INIS)

    Pirogova, G.N.; Voronin, Yu.V.; Pribylov, A.A.; Serpinskii, V.V.; Mirskii, Ya.V.; Almazova, B.B.; Golitsina, V.V.

    1993-01-01

    It is known that large quantities of 85 Kr are liberated during the operation of nuclear power plants and, in particular, during the processing of nuclear fuel. At the present time, there are several methods of its fixation (accumulation), viz., storage in high-pressure gas balloons, adsorption, plasma-aided implantation into metals, introduction into clathrate compounds, and obtaining kryptonates. Encapsulation in zeolites is one of the most promising methods. The merits of this method include safety during storage, a favorable volume-to-mass ratio, the possibility of separating krypton from a mixture of different gases, and purity of the encapsulated gas. The encapsulation technique has been developed quite recently. Several recent reports established the possibility of encapsulating krypton in the 3A-type zeolites. However, most of the investigators observed leakage during the storage of the zeolite-gas system and complete liberation of krypton from the zeolite during prolonged storage. This paper deals with a study of the encapsulation process of krypton in the zeolites obtained by cation exchange from NaA. The experimental specimens were characterized by the degree of exchange of sodium into potassium and cesium. It is known that the introduction of cesium into the structure (body) of a zeolite reduces the size of the window of entrance. All the synthesized specimens were used in their granulated form. The aim of this study was to develop zeolite specimens for carrying out long-term storage of krypton

  11. Treatment of Proliferative Diabetic Retinopathy: a Comparison of Krypton Green, Krypton Yellow and Krypton Red Lasers%三种波长氪离子激光治疗增殖期糖尿病性视网膜病变的疗效比较

    Institute of Scientific and Technical Information of China (English)

    王洁; 李军; 韩素珍

    2011-01-01

    目的 比较氪绿激光、氪黄激光和氪红激光治疗增殖期糖尿病性视网膜病变(PDR)的疗效.方法 PDR患者167例243只眼,随机分为氪绿激光、氪黄激光和氪红激光治疗组,行标准全视网膜光凝.比较三组患眼视力、新生血管的变化.结果 三组患者视力比较差异无显著意义(P>0.05).新生血管消退比较,氪绿激光组与氪红激光组比较差异无显著意义(P>0.05).氪黄激光组与氪绿激光组、氪红激光组比较差异有显著意义(P<0.05).结论 氪绿激光、氪黄激光和氪红激光对PDR均有治疗作用,氪绿激光和氪红激光的疗效较好.%Objective To investigate the therapeutic effect of the krypton green, krypton yellow or krypton red laser in the treatnent of proliferative diabetic retinopathy(PDR) .Methods Two hundred and forty-three eyes of 167 PDR patients were assigned randomly to receive either krypton green, krypton yellow or krypton red laser treatment, to investigate the changes in the vision and neovessels.Results There was no statistical difference among krypton green, krypton yellow and krypton red laser treatment for PDR(P>0. 05)in visual improvement, and also between krypton green with krypton red laser in neovessels loss, but there was statistical difference between krypton yellow with krypton green or krypton red laser in it.Conclusions The three kinds of krypton lasers all have therapeutic effect on PDR, but the krypton green and krypton red lasers should be preferred.

  12. [Effects of xenon and krypton-containing breathing mixtures on clinical and biochemical blood indices in animals].

    Science.gov (United States)

    Kussmaul', A R; Bogacheva, M A; Shkurat, T P; Pavlov, B N

    2007-01-01

    Effects of 24-hr breathing air mixtures containing xenon (XBM) and krypton (KBM) were compared in terms of hormonal status, and blood biochemical indices and morphology in laboratory animals. Some changes observed in blood and hormone indices could be a nonspecific adaptive response. Hence, we should elicit whether these effects are quickly reversible or long. For several indices krypton was a more favorable factor than xenon. However, some of its effects invite to delve into effects of different krypton concentrations on organism.

  13. Global Methane Initiative

    Science.gov (United States)

    The Global Methane Initiative promotes cost-effective, near-term methane recovery through partnerships between developed and developing countries, with participation from the private sector, development banks, and nongovernmental organizations.

  14. Accurate virial coefficients of gaseous krypton from state-of-the-art ab initio potential and polarizability of the krypton dimer

    Science.gov (United States)

    Song, Bo; Waldrop, Jonathan M.; Wang, Xiaopo; Patkowski, Konrad

    2018-01-01

    We have developed a new krypton-krypton interaction-induced isotropic dipole polarizability curve based on high-level ab initio methods. The determination was carried out using the coupled-cluster singles and doubles plus perturbative triples method with very large basis sets up to augmented correlation-consistent sextuple zeta as well as the corrections for core-core and core-valence correlation and relativistic effects. The analytical function of polarizability and our recently constructed reference interatomic potential [J. M. Waldrop et al., J. Chem. Phys. 142, 204307 (2015)] were used to predict the thermophysical and electromagnetic properties of krypton gas. The second pressure, acoustic, and dielectric virial coefficients were computed for the temperature range of 116 K-5000 K using classical statistical mechanics supplemented with high-order quantum corrections. The virial coefficients calculated were compared with the generally less precise available experimental data as well as with values computed from other potentials in the literature {in particular, the recent highly accurate potential of Jäger et al. [J. Chem. Phys. 144, 114304 (2016)]}. The detailed examination in this work suggests that the present theoretical prediction can be applied as reference values in disciplines involving thermophysical and electromagnetic properties of krypton gas.

  15. AKUT: a process for the separation of aerosols, krypton, and tritium from burner off-gas in HTR-fuel reprocessing

    International Nuclear Information System (INIS)

    Laser, M.; Barnert-Wiemer, H.; Beaujean, H.; Merz, E.; Vygen, H.

    1975-01-01

    The AKUT process consists of the following process steps: (1) aerosol retention by an electrostatic separator followed by HEPA filters, (2) oxidation of CO with O 2 or reaction of excess O 2 with CO, respectively, (3) compression, (4) scrubbing and/or liquefaction, (5) separation of krypton by distillation, and (6) separation of tritiated water and iodine by adsorption or chemical reaction. Liquefied off-gas with low permanent gas content resulting from graphite burning with oxygen may be distilled at ambient temperature. Off-gas with higher permanent gas content from burning with oxygen enriched air must be processed at lower temperature. The ambient temperature flow sheet is preferable from an economic as well as safety point of view. (U.S.)

  16. Relativistic configuration interaction treatment of generalized oscillator strength for krypton

    International Nuclear Information System (INIS)

    Wang Huangchun; Qu Yizhi; Liu Chunhua

    2007-01-01

    A fully relativistic configuration interaction method is developed to investigate the transition energies and general oscillator strengths of the lower lying states of krypton, for both optically allowed and optically forbidden transitions. The calculated results are in agreement with the recent experimental measurements. The calculated transition energies for the 5s and 5s' transitions are 9.970 and 10.717 eV, which agree with the experimental data of 10.033 and 10.643 eV. The calculated oscillator strengths are 0.211 and 0.170, comparable with the experimental results 0.214(±0.012) and 0.194 (±0.012), respectively. The momentum transfer positions (K 2 in a.u.) of the minimum and maximum GOSs in the 4s 2 4p 6 →4s 2 4p 5 (5s + 5s') transitions are 1.105 and 2.225, comparable with the measurements results 1.24 and 2.97. (authors)

  17. Amorphization, morphological instability and crystallization of krypton ion irradiated germanium

    International Nuclear Information System (INIS)

    Wang, L.M.; Birtcher, R.C.

    1991-01-01

    Krypton ion irradiation of crystalline Ge and subsequent thermal annealing were both carried out with in situ transmission electron microscopy observations. The temperature dependence of the amorphization dose, effect of foil thickness, morphological changes during continuous irradiation of the amorphous state as well as the effect of implanted gas have been determined. The dose of 1.5 MeV Kr required for amorphization increases with increasing temperature. At a fixed temperature, the amorphization dose is higher for thicker regions of the specimen. Continuous irradiation of amorphous Ge at room temperature results in a high density of small cavities which grow with increasing dose. Cavities do not coalesce during growth but develop into irregular-shaped holes that eventually transform the amorphous Ge into a sponge-like material. Formation of the spongy structure is independent of Kr implantation. The crystallization temperature and the morphology of recrystallized Ge depend on the Kr + dose. Voids are expelled from recrystallized Ge, while the sponge-like structure is retained after crystallization. (author)

  18. First Detection of Krypton and Xenon in a White Dwarf

    Science.gov (United States)

    Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

    2012-01-01

    We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 KrVI-VII and Xe VI-VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 plus or minus 0.5 and log Xe = -4.2 plus or minus 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the-precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and thaI the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell nash or a binary white dwarf merger.

  19. Detection of tobacco smoke deposition by hyperpolarized krypton-83 MRI.

    Science.gov (United States)

    Cleveland, Zackary I; Pavlovskaya, Galina E; Stupic, Karl F; Wooten, Jan B; Repine, John E; Meersmann, Thomas

    2008-02-01

    Despite the importance of the tobacco smoke particulate matter in the lungs to the etiology of pulmonary disease in cigarette smokers, little is currently known about the spatial distribution of particle deposition or the persistence of the resulting deposits in humans, and no satisfactory technique currently exists to directly observe tobacco smoke condensate in airways. In this proof-of-principle work, hyperpolarized (hp) 83Kr MRI and NMR spectroscopy are introduced as probes for tobacco smoke deposition in porous media. A reduction in the hp-83Kr longitudinal (T1) relaxation of up to 95% under near-ambient humidity, pressure and temperature conditions was observed when the krypton gas was brought into contact with surfaces that had been exposed to cigarette smoke. This smoke-induced acceleration of the 83Kr self-relaxation was observed for model glass surfaces that, in some experiments, were coated with bovine lung surfactant extract. However, a similar effect was not observed with hp-(129)Xe indicating that the 83Kr sensitivity to smoke deposition was not caused by paramagnetic species but rather by quadrupolar relaxation due to high adsorption affinity for the smoke deposits. The 83Kr T1 differences between smoke-treated and untreated surfaces were sufficient to produce a strong contrast in variable flip angle FLASH hp-83Kr MRI, suggesting that hp-83Kr may be a promising contrast agent for in vivo pulmonary MRI.

  20. High-energy krypton fluoride lasers for inertial fusion.

    Science.gov (United States)

    Obenschain, Stephen; Lehmberg, Robert; Kehne, David; Hegeler, Frank; Wolford, Matthew; Sethian, John; Weaver, James; Karasik, Max

    2015-11-01

    Laser fusion researchers have realized since the 1970s that the deep UV light from excimer lasers would be an advantage as a driver for robust high-performance capsule implosions for inertial confinement fusion (ICF). Most of this research has centered on the krypton-fluoride (KrF) laser. In this article we review the advantages of the KrF laser for direct-drive ICF, the history of high-energy KrF laser development, and the present state of the art and describe a development path to the performance needed for laser fusion and its energy application. We include descriptions of the architecture and performance of the multi-kilojoule Nike KrF laser-target facility and the 700 J Electra high-repetition-rate KrF laser that were developed at the U.S. Naval Research Laboratory. Nike and Electra are the most advanced KrF lasers for inertial fusion research and energy applications.

  1. Relativistic Configuration Interaction Treatment of Generalized Oscillator Strength for Krypton

    Institute of Scientific and Technical Information of China (English)

    WANG Huang-Chun; QU Yi-Zhi; LIU Chun-Hua

    2007-01-01

    A fully relativistic configuration interaction method is developed to investigate the transition energies and general oscillator strengths of the lower lying states of krypton, for both optically allowed and optically forbidden transitions. The calculated results are in agreement with the recent experimental measurements. The calculated transition energies for the 5s and 5s' transitions are 9.970 and 10.717eV, which agree with the experimental data of 10.033 and 10.643 eV. The calculated oscillator strengths are 0.211 and 0.170, comparable with the experimental results 0.214(±0.012) and 0.194 (±0.012), respectively. The momentum transfer positions ( K2 in a.u.) of the minimum and maximum GOSs in the 4s24p6 → 4s24p5 (5s + 5s') transitions are 1.105 and 2.225, comparable with the measurements results 1.24 and 2.97 [Phys. Rev. A 67 (2003) 062708].

  2. Radioactive Iodine and Krypton Control for Nuclear Fuel Reprocessing Facilities

    Directory of Open Access Journals (Sweden)

    Nick R. Soelberg

    2013-01-01

    Full Text Available The removal of volatile radionuclides generated during used nuclear fuel reprocessing in the US is almost certain to be necessary for the licensing of a reprocessing facility in the US. Various control technologies have been developed, tested, or used over the past 50 years for control of volatile radionuclide emissions from used fuel reprocessing plants. The US DOE has sponsored, since 2009, an Off-gas Sigma Team to perform research and development focused on the most pressing volatile radionuclide control and immobilization problems. In this paper, we focus on the control requirements and methodologies for 85Kr and 129I. Numerous candidate technologies have been studied and developed at laboratory and pilot-plant scales in an effort to meet the need for high iodine control efficiency and to advance alternatives to cryogenic separations for krypton control. Several of these show promising results. Iodine decontamination factors as high as 105, iodine loading capacities, and other adsorption parameters including adsorption rates have been demonstrated under some conditions for both silver zeolite (AgZ and Ag-functionalized aerogel. Sorbents, including an engineered form of AgZ and selected metal organic framework materials (MOFs, have been successfully demonstrated to capture Kr and Xe without the need for separations at cryogenic temperatures.

  3. Large area electron beam pumped krypton fluoride laser amplifier

    International Nuclear Information System (INIS)

    Sethian, J.D.; Obenschain, S.P.; Gerber, K.A.; Pawley, C.J.; Serlin, V.; Sullivan, C.A.; Webster, W.; Deniz, A.V.; Lehecka, T.; McGeoch, M.W.; Altes, R.A.; Corcoran, P.A.; Smith, I.D.; Barr, O.C.

    1997-01-01

    Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm x 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high x 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier has been fully integrated into the Nike system and is used on a daily basis for laser-target experiments. copyright 1997 American Institute of Physics

  4. Noble Liquid (Xenon or Krypton) Totally Active Calorimetry

    CERN Multimedia

    2002-01-01

    Main Goals\\\\ \\\\ Determine ionization and scintillation yields in liquid Xenon (LXe) or Krypton.\\\\ \\\\ Determine the electron lifetime and photon mean free path in LXe or LKr. \\\\ \\\\ Determine energy resolution of LXe or LKr via ionization or scintillation.\\\\ \\\\ Determine correlation of fluctuations between ionization and scintillation. Summary of Results \\\\ \\\\ -~measured the electron lifetime in LXe, ($\\tau$~$>$~400 $\\mu$s).\\\\ \\\\ -~measured the energy to create an ionization electron in LXe, W=9.8 eV.\\\\ \\\\ -~measured the energy to create a LXe scintillation photon, W$ _{s} $~=~14.2~eV. \\\\ \\\\ -~measured the anticorrelation of scintillation and ionization yields. \\\\ \\\\ -~measured the energy resolution in LXe via ionization, $ sigma _{E} / $E=0.07\\%/$\\sqrt$E(GeV). \\\\ \\\\ -~measured resolution in LXe via scintillation $ sigma _{E} / $E=0.24\\%/$\\sqrt$E(GeV)+0.26\\%. \\\\ \\\\ -~measured electron drift velocity in LXe:~neat (2.5 mm/$\\mu$s), doped (4.4~mm/$\\mu$s). \\\\ \\\\ -~measured the photon mean free path in LXe vs $ lambd...

  5. Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake

    DEFF Research Database (Denmark)

    Deutzmann, Joerg S.; Stief, Peter; Brandes, Josephin

    2014-01-01

    Anaerobic methane oxidation coupled to denitrification, also known as “nitrate/nitrite-dependent anaerobic methane oxidation” (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments......, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques...... in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were...

  6. Neutron production with mixture of deuterium and krypton in Sahand Filippov type plasma focus facility

    International Nuclear Information System (INIS)

    Mohammadi, M.A.; Sobhanian, S.; Rawat, R.S.

    2011-01-01

    This Letter reports the order of magnitude enhancement in neutron yield from Sahand plasma focus device with krypton seeded deuterium operation. The highest average neutron yield of 2.2x10 9 neutrons per shot was achieved at 1.00 Torr deuterium with 3% krypton which is higher than the best average neutron yield of 3.18x10 8 neutrons per shot for pure deuterium operation. Estimation of average neutron energy showed that the maximum and minimum average energies are 2.98±0.6 MeV at 16 kV in 0.25 Torr deuterium with 3% Kr and 2.07±0.2 MeV at 18 kV operation in 0.5 Torr deuterium with 3% Kr, respectively. The anisotropy of neutron emission from Sahand DPF showed that the neutrons are produced mainly by beam-target mechanisms. -- Highlights: → The highest average neutron yield of 2.2x10 9 neutrons per shot was achieved at mixture of deuterium and krypton. → In the krypton seeding of deuterium also anisotropy of neutron emission deuterium is found. → The krypton seeding of deuterium made the neutron emission more reliable over wider operating pressure ranges.

  7. Variability of atmospheric krypton-85 activity concentrations observed close to the ITCZ in the southern hemisphere.

    Science.gov (United States)

    Bollhöfer, A; Schlosser, C; Ross, J O; Sartorius, H; Schmid, S

    2014-01-01

    Krypton-85 activity concentrations in surface air have been measured at Darwin, which is located in northern Australia and is influenced by seasonal monsoonal activity. Measurements between August 2007 and May 2010 covered three wet seasons. The mean activity concentration of krypton-85 measured during this period was 1.31±0.02Bqm(-3). A linear model fitted to the average monthly data, using month and monsoon as predictors, shows that krypton-85 activity concentration measured during the sampling period has declined by 0.01Bqm(-3) per year. Although there is no statistically significant difference in mean activity concentration of krypton-85 between wet and dry season, the model implies that activity concentration is higher by about 0.015Bqm(-3) during months influenced by the monsoon when a north westerly flow prevails. Backward dispersion runs using the Lagrangian particle dispersion model Hysplit4 highlight possible source regions during an active monsoon located deep in the northern hemisphere, and include reprocessing facilities in Japan and India. However, the contribution of these facilities to krypton-85 activity concentrations in Darwin would be less than 0.003Bqm(-3). Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  8. Krypton separation from ambient air for application in collinear fast beam laser spectroscopy.

    Science.gov (United States)

    Mohamed, Tarek; Strohaber, James; Nava, Ricardo; Kolomenskii, Alexandre; Thonnard, Norbert; Schuessler, Hans A

    2012-07-01

    A portable apparatus for the separation of krypton from environmental air samples was tested. The apparatus is based on the cryogenic trapping of gases at liquid nitrogen temperature followed by controlled releases at higher temperatures. The setup consists of a liquid nitrogen trap for the removal of H(2)O and CO(2), followed by charcoal-filled coils that sequentially collect and release krypton and other gases providing four stages of gas chromatography to achieve separation and purification of krypton from mainly N(2), O(2), and Ar. Residual reactive gases remaining after the final stage of chromatography are removed with a hot Ti sponge getter. A thermal conductivity detector is used to monitor the characteristic elution times of the various components of condensed gases in the traps during step-wise warming of the traps from liquid nitrogen temperatures to 0 °C, and then to 100 °C. This allows optimizing the switching times of the valves between the stages of gas chromatography so that mainly krypton is selected and loaded to the next stage while exhausting the other gases using a He carrier. A krypton separation efficiency of ~80 % was determined using a quadrupole mass spectrometer.

  9. A biomimetic methane-oxidising catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Dalton, H [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

    1997-12-31

    The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

  10. A biomimetic methane-oxidising catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Dalton, H. [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

    1996-12-31

    The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

  11. Study of Krypton-Silver, Krypton-gold, Krypton-thorium interactions at 27 and 43 MeV/n in terms of global variables

    International Nuclear Information System (INIS)

    Lemiere, J.

    1992-07-01

    The determination of desexcitation mechanism of hot and compressed nuclear systems formed after heavy ions collisions at intermediate energies asks for and exclusive and complete detection of the products of the reaction and so the use of multidetectors with large angular coverage. In this work, we study fragment production (Z>8) in nuclear collisions of krypton projectiles accelerated at 27 MeV/uma and 43 MeV/uma with silver, gold and thorium target with the help of the measurements provided by two gaseous multidetectors DELF and XYZT at GANIL. We observed events with a multiplicity of fragments up to 5 and 6 at 27 and 43 MeV/uma respectively (whatever the nature of target). We restricted our study to central collisions with at least 3 heavy fragments detected by separating peripheral collisions which had kept the memory of entrance channel. The recoil velocity of fragments for central events indicates high excitation energy which is comparable to total binding energy of the system. In order to normalize and compact the information which represent the velocities and charges of the 3, 4 or 5 detected fragments, we used several global variables as flow angle and isotropy ratio. We tested if these variables were no too modified by the limitations of the experimental setup by using Monte Carlo simulations. We observed some important differences between the systems we used: first, more events with large flow angle or isotropy ratio for the gold target than for the silver one, second relatively more events with large isotropy ratio for 43 MeV/uma than for 27 MeV/uma. Events with small flow angle has a weak memory of the entrance channel, but the events with large flow angle do not, this indicates the flow angle to be an estimation of impact parameter. The difference between gold and silver target has been assumed to be due to the difference of overlap cross section of the Kr-Au and Kr-Ag systems

  12. Answers to questions about removing krypton from the Three Mile Island, Unit 2 reactor building. Public information report

    International Nuclear Information System (INIS)

    1980-05-01

    This document presents answers to frequently asked questions about the probable effects of controlled releases of the krypton presently contained within the reactor building of Three Mile Island, Unit 2. Also answered are questions about alternative means for removing the krypton

  13. Determination of SO2 in the atmosphere using radioactive iodine kryptonate as impregnation medium of chromatographic paper

    International Nuclear Information System (INIS)

    Pruzinec, J.

    1975-01-01

    Chromatographic paper was impregnated with radioiodine kryptonate using the macrodiffusion technique. The decrease with time of the activity of the kryptonate-impregnated paper exposed to SO 2 -contaminated air was measured. From the decrease in chromatographic paper activity, the concentration of SO 2 was determined in the range 300 to 700 ppm. (A.K.)

  14. A mechanistic model on methane oxidation in the rice rhizosphere

    NARCIS (Netherlands)

    Bodegom, van P.M.; Leffelaar, P.A.; Goudriaan, J.

    2001-01-01

    A mechanistic model is presented on the processes leading to methane oxidation in rice rhizosphere. The model is driven by oxygen release from a rice root into anaerobic rice soil. Oxygen is consumed by heterotrophic and methanotrophic respiration, described by double Monod kinetics, and by iron

  15. Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics.

    Science.gov (United States)

    Murialdo, Maxwell; Stadie, Nicholas P; Ahn, Channing C; Fultz, Brent

    2015-07-28

    Krypton adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric enthalpy of adsorption, rising by up to 1.4 kJ mol(-1) as a function of coverage. This increase is a result of enhanced adsorbate-adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate-adsorbate interactions is made by comparing the measured isosteric enthalpies of adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases.

  16. Doses from radioactive methane

    International Nuclear Information System (INIS)

    Phipps, A.W.; Kendall, G.M.; Fell, T.P.; Harrison, J.D.

    1990-01-01

    A possible radiation hazard arises from exposure to methane labelled with either a 3 H or a 14 C nuclide. This radioactive methane could be released from a variety of sources, e.g. land burial sites containing radioactive waste. Standard assumptions adopted for vapours would not apply to an inert alkane like methane. This paper discusses mechanisms by which radioactive methane would irradiate tissues and provides estimates of doses. Data on skin thickness and metabolism of methane are discussed with reference to these mechanisms. It is found that doses are dominated by dose from the small fraction of methane which is inhaled and metabolised. This component of dose has been calculated under rather conservative assumptions. (author)

  17. Continuous determination of regional myocardial blood flow with intracoronary krypton-81m in coronary artery disease

    International Nuclear Information System (INIS)

    Remme, W.J.; Krauss, X.H.; van Hoogenhuyze, D.C.; Cox, P.H.; Storm, C.J.; Kruyssen, D.A.

    1985-01-01

    Pacing-induced changes in regional coronary flow were studied continuously with krypton-81m by intracoronary infusion in 25 patients: 21 with 50% or greater diameter narrowing of 1 or more left coronary arteries (group I) and 4 with less than 50% diameter reduction of a left coronary artery (group II). No changes occurred in group II. In group I, krypton-81m perfusion decreased progressively in all areas with more than 70% diameter narrowing, with a simultaneous increase in normal regions. At the end of pacing during angina, krypton-81m perfusion was reduced to 81 +/- 4% of control in areas with 71 to 90% diameter reduction (n = 8) and to 69 +/- 6% in areas with more than 90% diameter narrowing (n = 15). In contrast, in regions with 50 to 70% diameter reduction changes were variable (decrease in 4 regions, increase in 2 and an unchanged distribution in 1 region). Krypton-81m perfusion decreased early, before general signs of ischemia in areas with more than 90% diameter reduction, whereas this decrease occurred later in regions with 71 to 90% diameter narrowing, concurrently with ST-segment changes but before anginal pain. Although all signs of ischemia had disappeared between 2 and 5 minutes after pacing, changes in krypton-81m distribution persisted in most areas for 5 to 15 minutes after pacing. It is concluded that the functional significance of coronary arterial narrowing can be assessed with a continuous intracoronary infusion of krypton-81m. Changes in regional distribution persisted after cessation of pacing-induced ischemia, indicating an ongoing decrease in regional myocardial blood flow

  18. Methane yield enhancement via electroporation of organic waste.

    Science.gov (United States)

    Safavi, Seyedeh Masoumeh; Unnthorsson, Runar

    2017-08-01

    An experimental study with pulsed electric field (PEF) pre-treatment was conducted to investigate its effect on methane production. PEF pre-treatment converts organic solids into soluble and colloidal forms, increasing bioavailability for anaerobic microorganisms participating in methane generation process. The substrates tested were landfill leachate and fruit/vegetable. Three treatment intensities of 15, 30, and 50kWh/m 3 were applied to investigate the influence of pre-treatment on methane production via biochemical methane potential test. Threshold treatment intensity was found to be around 30kWh/m 3 for landfill leachate beyond which the methane production enhanced linearly with increase in intensity. Methane production of the landfill leachate significantly increased up to 44% with the highest intensity. The result of pulsed electric field pre-treatment on fruit/vegetable showed that 15kWh/m 3 was the intensity by which the highest amount of methane (up to 7%) was achieved. Beyond this intensity, the methane production decreased. Chemical oxygen demand removals were increased up to 100% for landfill leachate and 17% for fruit/vegetable, compared to the untreated slurries. Results indicate that the treatment intensity has a significant effect on the methane production and biosolid removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. X-ray spectroscopic measurements of dielectronic recombination of highly charged krypton ions

    International Nuclear Information System (INIS)

    Biedermann, C.; Fuchs, T.; Liebisch, P.; Radtke, R.; Behar, E.; Doron, R.

    1999-01-01

    We have performed X-ray spectroscopic measurements of the dielectronic recombination (DR) resonance strengths for the KLn (n = 2, .., 5) series of He-, Li-, and Be-like krypton ions. The ions were produced with an electron beam ion trap, and the strengths were obtained from a fit procedure that compares the experimental excitation function for DR to theory. The results agree well with the predictions. By looking at the KLL resonance, the time evolution of different krypton charge states was measured with this technique and compared with a model of the trap inventory. (orig.)

  20. Generalized oscillator strengths for some higher valence-shell excitations of krypton atom

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence-shell excitations in 4d, 4f, 5p, 5d, 6s, 6p, 7s ← 4p of krypton atom have been determined. Their profiles are discussed, and the generalized oscillator strengths for the electric monopole and quadrupole excitations in 5p ← 4p are compared with the calculations of Amusia et al. (Phys. Rev. A 67 022703 (2003)). The differences between the experimental results and theoretical calculations show that more studies are needed.

  1. Immobilization of krypton-85 in zeolite 5A and porous glass

    International Nuclear Information System (INIS)

    Christensen, A.B.; DelDebbio, J.A.; Knecht, D.A.; Tanner, J.E.; Cossel, S.C.

    1981-12-01

    This report demonstrates the technical and economic feasibility for immobilizing krypton-85 by high pressure/high temperature encapsulation in zeolite 5A or thirsty Vyco porous glass. Data are presented to show how process conditions affect the encapsulation and how to compact the zeolite beads with glass frit or other additives to form a fused mass with low dispersibility potential. Krypton specific loadings of 30 and 50 m 3 STP gas per m 3 solid are readily achieved at 100 MPa in porous glass at 900 0 C and zeolite 5A at 700 0 C. Krypton is encapsulated by a sintering process where the porous glass and zeolite 5A voids are sealed. With zeolite 5A, the initial water concentration has a catalytic effect on the sintering, resulting in a transition from crystalline zeolite 5A to an amorphous aluminosilicate. Krypton leakage experiments are used to predict leakage rates from glass or zeolite of less than 0.03% and 0.3% for 10-y storage at 300 and 400 0 C, respectively. Heating the loaded zeolite at 600 to 700 0 C for 4 h removes 0.1% of the total krypton which is loosely held and reduces the subsequent leakage rates at 300 to 400 0 C. Zeolite 5A is chosen as the preferred material to immobilize krypton-85. A preconceptual design and cost estimate is given for a facility to encapsulate 110% of the krypton production of a 2000 metric ton of heavy metal per year reprocessing plant, or 230 m 3 of gas containing 19 MCi of krypton-85. A hot isostatic press (HIP) with an isolated work zone of 8 or 16 L capacity is required to operate for 600 or 300 cycles per year, respectively. Existing HIP technology uses work zones from 1 to 3500 L capacity at similar production rates. A preliminary safety evaluation shows that an incredible worst case accident could be contained and the maximum off-site dose would be well below accident protective action guidance levels

  2. Extreme-ultraviolet wavelength and lifetime measurements in highly ionized krypton

    CERN Document Server

    Kukla, K W; Vogt, C M V; Berry, H G; Dunford, R W; Curtis, L J; Cheng, S

    2005-01-01

    We have studied the spectrum of highly ionized krypton in the extreme-ultraviolet wavelength region (50-300 Aa), using beam-foil excitation of fast krypton ions at the Argonne ATLAS accelerator facility. We report measurements of transition wavelengths and excited-state lifetimes for n=2 states in the lithiumlike, berylliumlike, and boronlike ions, Kr/sup 31+,32+,33+/. Excited state lifetimes ranging from 10 ps to 3 ns were measured by acquiring time- of-flight-delayed spectra with a position-sensitive multichannel detector.

  3. Radiation protection problems in using krypton 81 m in pulmonary ventilation scintiscanning

    International Nuclear Information System (INIS)

    Spesshardt, K.

    1982-01-01

    The experience gained in using the krypton-81 generator as regards radiation protection is briefly outlined by means of measurements, carried through in the framework of the operation licensing procedure. It turned out that while krypton is a very helpful substance in clinical investigations on account of its favourable gamma energy and very short half-life, it does create some radiation protection problems. The radiation protection measures carried through at the inhalation system can be described as satisfactory. Improvements are due at the filter system between generator and breathing mask. (orig./DG) [de

  4. Krypton separation from waste gas of a reprocessing plant by low temperature rectification

    International Nuclear Information System (INIS)

    1987-01-01

    6 lectures at this seminar describe and evaluate the results of the research and development work on low temperature krypton separation from the waste gas of the reprocessing of nuclear fuels. They are used for making decisions for the process to be used in the future on a large scale at the Wackersdorf reprocessing plant. 2 further lectures deal with alternatives to this process, which were also developed: the freon washing and low temperature adsorption of krypton. All the lectures were included separately in the INIS and ENERGY databases. (RB) [de

  5. The dielectronic satellites to the 2s-3p Ne-like krypton resonance lines

    International Nuclear Information System (INIS)

    Khakhalin, S.Ya.; Dyakin, V.M.; Faenov, A.Ya.; Fiedorowicz, H.; Bartnik, A.; Parys, P.; Nilsen, J.; Osterheld, A.

    1994-01-01

    We present an analysis of dielectronic satellite spectra of 2p 6 -2s2p 6 3p Ne-like krypton resonance lines. The satellite structure was registered with high (better than λ/Δλ > 3500) spectral resolution in the emission of a laser irradiated gas puff target. We perform an unambiguous identification of satellite lines caused by radiative transitions from autoionizing states of sodium-like krypton ions. A total of about 20 spectral features are identified, most of them for the first time. Very good agreement between the satellite structure calculations and experimental emission spectra is obtained. (orig.)

  6. The effect of annealing unimplanted and krypton implanted uranium dioxide using positrons

    International Nuclear Information System (INIS)

    Evans, H.E.; Rice-Evans, P.; Smith, D.L.; Smith, C.; Evans, J.H.

    1992-01-01

    Previous studies examining the response of variable energy positrons to metals implanted with krypton ions have been extended to UO 2 . The behaviour of two Kr-implanted samples (one implanted at 300 K, the other at 870 K) during annealing up to 1350 K has been followed, together with an unimplanted, as-polished sample. There are several features of interest in the results although in these initial studies the interpretation is not always clear. Defect recovery and krypton effects can be identified but at high temperatures some suggestion of a sensitivity of positrons to stoichiometry is present

  7. The dielectronic satellites to the 2s-3p Ne-like krypton resonance lines

    Energy Technology Data Exchange (ETDEWEB)

    Khakhalin, S.Ya. (MISDC, NPO ' ' VNIIFTRI' ' , Mendeleevo (Russian Federation)); Dyakin, V.M. (MISDC, NPO ' ' VNIIFTRI' ' , Mendeleevo (Russian Federation)); Faenov, A.Ya. (MISDC, NPO ' ' VNIIFTRI' ' , Mendeleevo (Russian Federation)); Fiedorowicz, H. (Inst. of Optoelectronics, Warsaw (Poland)); Bartnik, A. (Inst. of Optoelectronics, Warsaw (Poland)); Parys, P. (Inst. of Plasma Physics and Laser Microfusion, Warsaw (Poland)); Nilsen, J. (Lawrence Livermore National Lab., Livermore, CA (United States)); Osterheld, A. (Lawrence Livermore National Lab., Livermore, CA (United States))

    1994-08-01

    We present an analysis of dielectronic satellite spectra of 2p[sup 6]-2s2p[sup 6]3p Ne-like krypton resonance lines. The satellite structure was registered with high (better than [lambda]/[Delta][lambda] > 3500) spectral resolution in the emission of a laser irradiated gas puff target. We perform an unambiguous identification of satellite lines caused by radiative transitions from autoionizing states of sodium-like krypton ions. A total of about 20 spectral features are identified, most of them for the first time. Very good agreement between the satellite structure calculations and experimental emission spectra is obtained. (orig.).

  8. Self-Associating Behavior of Acetone in Liquid Krypton.

    Science.gov (United States)

    De Beuckeleer, Liene I; Herrebout, Wouter A

    2016-02-18

    Acetone molecules are inclined to self-associate through dipole-dipole interactions because of their large dipole moment. Infrared spectroscopy of compounds dissolved in liquid noble gases supported by high level ab initio calculations allows investigating the self-associating behavior and determining the thermodynamical properties. In this study, infrared spectra of various concentrations of acetone dissolved in liquid krypton are recorded at constant temperature. Overlapping monomer and dimer spectra are separated by analyzing the obtained data sets with numerical methods based on least-squares fitting. Although acetone is known to self-associate, only a few spectral features have been presented in literature before. In this study, the application of new numerical approaches succeeds in resolving overlapping spectra and allows observing isolated acetone dimer absorption bands for the complete mid infrared spectrum. By use of data sets of spectra recorded at temperatures between 134 and 142 K, the experimental standard dimerization enthalpy was determined to be -10.8 kJ mol(-1). MP2/aug-cc-pVDZ calculations predicted a stacked and planar dimer geometry of which the stacked geometry is more stable. Combining MP2 energies and single point corrections involving CCSD(T) calculations and complete basis set extrapolations based on the MP2/aug-cc-pVDZ equilibrium geometry lead to complexation energy of -28.4 kJ mol(-1) for the stacked geometry and -15.1 kJ mol(-1) for the planar geometry. The corresponding values for the complexation enthalpies in solution, obtained by combining these values with corrections for thermal and solvent influences are -13.7 and -5.8 kJ mol(-1).

  9. Utilization of coalbed methane

    Energy Technology Data Exchange (ETDEWEB)

    Gustavson, J.B. [Gustavson Associates Inc., Boulder, CO (United States)

    1996-02-01

    Substantial progress has been made in capturing coalbed methane (CBM gas), which constitutes a valuable source of clean burning energy. It is of importance to study the various potential uses of coalbed methane and to understand the various technologies required, as well as their economics and any institutional constraints. In industrialised countries, the uses of coalbed methane are almost solely dependent on microeconomics; coalbed methane must compete for a market against natural gas and other energy sources - and frequently, coalbed methane is not competitive against other energy sources. In developing countries, on the other hand, particularly where other sources of energy are in short supply, coalbed methane economics yield positive results. Here, constraints to development of CBM utilization are mainly lack of technology and investment capital. Sociological aspects such as attitude and cultural habits, may also have a strong negative influence. This paper outlines the economics of coalbed methane utilization, particularly its competition with natural gas, and touches upon the many different uses to which coalbed methane may be applied. 24 refs., 4 figs.

  10. Direct Activation Of Methane

    KAUST Repository

    Basset, Jean-Marie; Sun, Miao; Caps, Valerie; Pelletier, Jeremie; Abou-Hamad, Edy

    2013-01-01

    Heteropolyacids (HPAs) can activate methane at ambient temperature (e.g., 20.degree. C.) and atmospheric pressure, and transform methane to acetic acid, in the absence of any noble metal such as Pd). The HPAs can be, for example, those with Keggin

  11. Methane and Climate Change

    NARCIS (Netherlands)

    Reay, D.; Smith, P.; Amstel, van A.R.

    2010-01-01

    Methane is a powerful greenhouse gas and is estimated to be responsible for approximately one-fifth of man-made global warming. Per kilogram, it is 25 times more powerful than carbon dioxide over a 100-year time horizon -- and global warming is likely to enhance methane release from a number of

  12. Quenching of the resonance 5s({sup 3}P{sub 1}) state of krypton atoms in collisions with krypton and helium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Zayarnyi, D A; L' dov, A Yu; Kholin, I V [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2014-11-30

    The processes of collision quenching of the resonance 5s[3/2]{sub 1}{sup o}({sup 3}P{sub 1}) state of the krypton atom are studied by the absorption probe method in electron-beam-excited high-pressure He – Kr mixtures with a low content of krypton. The rate constants of plasmochemical reactions Kr* + Kr + He → Kr*{sub 2} + He [(4.21 ± 0.42) × 10{sup -33} cm{sup 6} s{sup -1}], Kr* + 2He → HeKr* + He [(4.5 ± 1.2) × 10{sup -36} cm{sup 6} s{sup -1}] and Kr* + He → products + He [(2.21 ± 0.22) × 10{sup -15} cm{sup 3} s{sup -1}] are measured for the first time. The rate constants of similar reactions are refined for krypton in the metastable 5s[3/2]{sub 2}{sup o} ({sup 3}P{sub 2}) state. (laser applications and other topics in quantum electronics)

  13. Preliminary safety evaluation of a commercial-scale krypton-85 encapsulation facility

    International Nuclear Information System (INIS)

    Christensen, A.B.; Tanner, J.E.; Knecht, D.A.

    1980-01-01

    This paper demonstrates that a commercial-scale facility for encapsulating krypton-85 in zeolite-5A or glass at a 2000 MTHM per year nuclear fuel reprocessing plant can be designed to contain fragments and the 340 to 850 kCi krypton-85 inventory from an assumed catastrophic failure of the high pressure vessel. The vessel failure was assumed as a worst case and was not based on a detailed design evaluation or operating experience. The process design is based on existing commercial hot isostatic pressing technology operated at up to 40 times the scale required for krypton encapsulation. From the calculated process gas inventory in the pressure vessel and vessel design, the maximum explosive energy of 8.4 kg TNT and resulting vessel plug and fragment velocities were calculated. The facility Containment Cell housing the high pressure vessel was designed to contain the gases, fragments, and the shock wave energy calculated for a hypothetical vessel failure. The Access Cell located directly above the Containment Cell was designed to be a tertiary confinement of krypton-85, should the access hatch be breached. 3 figures, 2 tables

  14. Effects of control technology on the projected krypton-85 environmental inventory

    International Nuclear Information System (INIS)

    Oscarson, E.E.

    1973-01-01

    Growth projections for the USA nuclear power industry may be used to make projections of future radioactive material inventories available for potential release to the environment. Since krypton-85 is produced in reactors, the potential routes of release to the environment are at the reactors or the fuel reprocessing plants. The present generation of reactors and fuel reprocessing plants do not use any systems to limit the release of krypton-85 into the biosphere. Clean-up systems are currently being designed and could be introduced when necessary. The cumulative inventory of krypton-85 in the environment is dependent upon the time of introduction of these clean-up systems and their efficiencies, in addition to the total quantity produced. Annual and cumulative inventories of krypton-85 are projected to increase dramatically over the next 50 years. If controls are assumed to be initiated at various years, a series of graphs of different cumulative environmental inventories and the associated doses and health effects are drawn. Varying the year of introduction and the efficiency of these systems allows one to speculate as to the optimum time for control implementation

  15. Use of krypton laser stimulation in the treatment of dry eye syndrome

    Science.gov (United States)

    Kecik, Tadeusz; Switka-Wieclawska, Iwona; Ciszewska, Joanna; Portacha, Lidia

    1991-08-01

    We''d like to present the use of krypton laser stimulation in the treatment of dry eye syndrom. 10 patients with dry eye syndrom were treated with irradiation of the lacrimal gland. Schirmer test and break up time were performed before and after therapy. After 10 days of treatment we observed higher value of secreted tear amount.

  16. Production and recombination of radiation defects in argon and krypton crystals

    International Nuclear Information System (INIS)

    Giersberg, E.J.

    1981-01-01

    Relative changes in the lattice constants of argon and krypton crystals have been measured by X-ray diffraction. As a result X-ray irradiation is found to produce stable defects. The recombination behaviour of these defects can be determined by isochronous and isothermal annealing. The creation of primary defects can be explained by exciton excitation and double-ionisation. (orig.) [de

  17. Environmental consequences of atmosphereic krypton-85. Final report, January 1, 1977-September 30, 1979

    International Nuclear Information System (INIS)

    Boeck, W.L.

    1979-01-01

    Krypton-85 is a radioactive inert gas produced during normal operations of the nuclear fuel cycle. The quantities of krypton-85, that will be produced in the next century, are sufficient, if released, to alter the electrical state of the atmosphere. The principal hypothesis is that an anthropogenic alteration of the electric state of the atmosphere could alter other meterological phenomena and lead to significant environmental impacts. The goal of this project was to explore some areas of basic science related to the evaluation of that hypothesis. The approach was primarily theoretical. The following topics were addressed: a first approximation model to estimate the effects of krypton-85 on the electrical state of the atmosphere; an analysis of the pathways between krypton-85 production and the atmosphere; an analytical model for fair weather atmospheric electricity; and a dipole model for atmospheric electricity. The results will provide a framework on which detailed models can be built. The results should provide better understanding of some topics in atmospheric electricity

  18. Resonance ionization spectroscopy of argon, krypton, and xenon using vacuum ultraviolet light

    International Nuclear Information System (INIS)

    Kramer, S.D.

    1984-04-01

    Resonant, single-photon excitation of ground state inert gases requires light in the vacuum ultraviolet spectral region. This paper discusses methods for generating this light. Efficient schemes for ionizing argon, krypton, and xenon using resonant, stepwise single-photon excitation are presented

  19. Krypton-85 Monitoring at BfS in Germany and Technical Solutions for Safeguards

    International Nuclear Information System (INIS)

    Schlosser, C.; Klingberg, F.

    2015-01-01

    The radioactive noble gas isotope krypton-85 with a half-life of 10.76 years is produced by nuclear fission. The main source of krypton-85 in the atmosphere are releases from reprocessing plants for nuclear fuel in the Northern Hemisphere. This volatile isotope is not retained in such plants and thus a very good indicator for the processing of irradiated nuclear fuel. This includes reprocessing for military purposes. Additionally, Kr-85 could be used as tracer for the validation of Atmospheric Transport Models. The German Federal Office for Radiation Protection (BfS) operates a noble gas laboratory and a global network which continuously monitors the krypton-85 activity concentrations in ground level air since the 1970s. The atmospheric activity concentration has continuously been increasing since the installation of reprocessing plants for nuclear fuels in the early 1950s until 2003. In the first decades it came mostly from military applications and later from civil reprocessing. Since 2003 the atmospheric krypton-85 background level in the Northern Hemisphere is nearly constant with a value of around 1.5 Bq/m 3 in Central Europe. The baseline is superimposed by spikes as a result from discharges of two European reprocessing plants of nuclear fuel, Sellafield and La Hague. The laboratory of the BfS and the techniques used will be presented. Long time series will be discussed and the use of ATM for source location demonstrated. (author)

  20. Calculation of partial enthalpies in argon-krypton mixtures by NPT molecular dynamics

    NARCIS (Netherlands)

    Sindzingre, P.; Massobrio, C.; Ciccotti, G.; Frenkel, D.

    1989-01-01

    In an earlier paper, we have indicated how, by using a particle-insertion technique, partial molar enthalpies and related quantities can be evaluated from simulations on a single state point. In the present paper we apply this method to a Lennard-Jones argon-krypton mixture. For this particular

  1. Study of structural and transport properties of argon, krypton, and their binary mixtures at different temperatures.

    Science.gov (United States)

    Ghimire, Sunil; Adhikari, Narayan Prasad

    2017-03-01

    Molecular dynamics simulation of argon, krypton, and their binary mixtures were performed at different temperatures and constant pressure (P = 1.013 bar) using GROMACS - Groningen Machine for Chemical Simulations. The gases are modeled by Lennard-Jones pair potential, with parameters taken from the literature. The study of radial distribution functions (RDFs) shows a single peak which indicates that there is no packing effect in gaseous state for argon, krypton, and their binary mixtures. The self-diffusion coefficients of argon and krypton is determined by using mean-square displacement(MSD) method and the mutual diffusion coefficients of binary mixtures are determined using Darken's relation. The values of simulated diffusion coefficients are compared with their corresponding theoretical values, numerical estimation, and experimental data. A good agreement between these sets of data is found. The diffusion coefficients obey Arrhenius behavior to a good extent for both pure components and binary mixtures. The values of simulated diffusion coefficient are used to estimate viscosities and thermal conductivities which agree with theoretical values, numerical estimation, and experimental data within 10 %. These results support that the LJ potential is sufficient for description of molecular interactions in argon and krypton.

  2. In Situ Measurement of Atmospheric Krypton and Xenon on Mars with Mars Science Laboratory

    Science.gov (United States)

    Conrad, P. G.; Malespin, C. A.; Franz, H. B.; Pepin, R. O.; Trainer, M. G.; Schwenzer, S. P.; Atreya, S. K.; Freissinet, C.; Jones, J. H.; Manning, H.; hide

    2016-01-01

    Mars Science Laboratorys Sample Analysis at Mars (SAM) investigation has measured all of the stable isotopes of the heavy noble gases krypton and xenon in the martian atmosphere, in situ, from the Curiosity Rover at Gale Crater, Mars. Previous knowledge of martian atmospheric krypton and xenon isotope ratios has been based upon a combination of the Viking missions krypton and xenon detections and measurements of noble gas isotope ratios in martian meteorites. However, the meteorite measurements reveal an impure mixture of atmospheric, mantle, and spallation contributions. The xenon and krypton isotopic measurements reported here include the complete set of stable isotopes, unmeasured by Viking. The new results generally agree with Mars meteorite measurements but also provide a unique opportunity to identify various non-atmospheric heavy noble gas components in the meteorites. Kr isotopic measurements define a solar-like atmospheric composition, but deviating from the solar wind pattern at 80Kr and 82Kr in a manner consistent with contributions originating from neutron capture in Br. The Xe measurements suggest an intriguing possibility that isotopes lighter than 132Xe have been enriched to varying degrees by spallation and neutron capture products degassed to the atmosphere from the regolith, and a model is constructed to explore this possibility. Such a spallation component, however, is not apparent in atmospheric Xe trapped in the glassy phases of martian meteorites.

  3. Liquid--vapor isotope fractionation factors in argon--krypton binary mixtures

    International Nuclear Information System (INIS)

    Lee, M.W.; Neufeld, P.; Bigeleisen, J.

    1977-01-01

    An equilibrium isotope effect has been studied as a continuous function of the potential field acting on the atom undergoing isotopic exchange. This has been accomplished through a study of the liquid vapor isotope fractionation factors for both, 36 Ar/ 40 Ar and 80 Kr/ 84 Kr in a series of binary mixtures which span the range between the pure components at 117.5 0 K. The 36 Ar/ 40 Ar fractionation factor increases (linearly) from (lnα)2.49 x 10 -3 in pure liquid argon to 2.91 x 10 -3 in an infinitely dilute solution in liquid krypton. Conversely, the 80 Kr/ 84 Kr fractionation factor decreases (linearly) from (lnα)0.98 x 10 -3 in pure liquid krypton to 0.64 x 10 -3 in an infinetely dilute solution in pure liquid argon. The mean force constants 2 U>/sub c/ on both argon and krypton atoms in the mixtures are derived from the respective isotope fractionation factors.The mean force constants for argon and krypton as a function of composition have been calculated by a modified corresponding states theory which uses the pure liquids as input parameters. The discrepancy is 8 percent at X/sub Ar/ + O. A systematic set of calculations has been made of 2 U> (Ar) and 2 U> (Kr) as a function of composition using radial distribution functions generated by the Weeks--Chandler--Anderson perturbation theory

  4. Preliminary safety evaluation of a commercial-scale krypton-85 encapsulation facility

    International Nuclear Information System (INIS)

    Christensen, A.B.; Tanner, J.E.; Knecht, D.A.

    1980-09-01

    This report demonstrates that a commercial-scale facility for encapsulating krypton-85 in zeolite-5A or glass at a 2000 MTHM per year nuclear fuel reprocessing plant can be designed to contain fragments and the 340 to 850 kCi krypton-85 inventory from an assumed catastrophic failure of the high pressure vessel. The vessel failure was assumed as a worst case and was not based on a detailed design evaluation or operating experience. The process design is based on existing commercial hot isostatic pressing technology operated at up to 40 times the scale required for krypton encapsulation. From the calculated process gas inventory in the pressure vessel and vessel design, the explosive energy of 8.4 kg TNT and vessel plug and fragment velocities were calculated. The facility Containment Cell housing the high pressure vessel was designed to contain the gases, fragments, and the shock wave energy calculated for vessel failure. The Access Cell located directly above the Containment Cell was designed to be a tertiary confinement of krypton-85, should the access hatch be breached

  5. Immobilization of krypton in a metallic matrix by combined ion implantation and sputtering

    International Nuclear Information System (INIS)

    Whitmell, D.S.

    1980-01-01

    With the increase in nuclear power, it may be necessary to contain for 100 to 200 years the radioactive 85 krypton released during fuel reprocessing. The ideal method of immobilizing radioactive materials is in the form of stable, monolithic solids which are resistant to the effects of the environment or accidents, and which can retain the radioactivity under all envisaged conditions. Since krypton is a rare gas, not forming thermally stable compounds, conventional methods of storage are not possible. A process is being developed to immobilize the krypton in the form of small gas bubbles in a metal matrix by implanting the gas into a metal layer from a glow discharge and then burying the implanted layer by sputter deposition. By repeating the process, a thick layer of deposit is built up with the krypton dispersed throughout the matrix as bubbles of diameter less than 20 A. This process offers an ideal form of storage since gas in bubbles is not thermally released until the temperature of the matrix is close to the melting point, and also leakage of gas by corrosion or mechanical damage will be small. A pilot plant is being built in order to demonstrate the process on a scale comparable with that required for a reprocessing plant. The efficiency of the process is dependent upon the amount of gas which can be implanted at low energy into a thin layer and its subsequent retention. (author)

  6. Effective and accurate approach for modeling of commensurate-incommensurate transition in krypton monolayer on graphite.

    Science.gov (United States)

    Ustinov, E A

    2014-10-07

    Commensurate-incommensurate (C-IC) transition of krypton molecular layer on graphite received much attention in recent decades in theoretical and experimental researches. However, there still exists a possibility of generalization of the phenomenon from thermodynamic viewpoint on the basis of accurate molecular simulation. Recently, a new technique was developed for analysis of two-dimensional (2D) phase transitions in systems involving a crystalline phase, which is based on accounting for the effect of temperature and the chemical potential on the lattice constant of the 2D layer using the Gibbs-Duhem equation [E. A. Ustinov, J. Chem. Phys. 140, 074706 (2014)]. The technique has allowed for determination of phase diagrams of 2D argon layers on the uniform surface and in slit pores. This paper extends the developed methodology on systems accounting for the periodic modulation of the substrate potential. The main advantage of the developed approach is that it provides highly accurate evaluation of the chemical potential of crystalline layers, which allows reliable determination of temperature and other parameters of various 2D phase transitions. Applicability of the methodology is demonstrated on the krypton-graphite system. Analysis of phase diagram of the krypton molecular layer, thermodynamic functions of coexisting phases, and a method of prediction of adsorption isotherms is considered accounting for a compression of the graphite due to the krypton-carbon interaction. The temperature and heat of C-IC transition has been reliably determined for the gas-solid and solid-solid system.

  7. Krypton-85 disposal program. Semiannual report, August 15, 1977--March 31, 1978

    International Nuclear Information System (INIS)

    Klett, R.D.

    1979-02-01

    The first 7.5 months of the Krypton-85 disposal program are summarized. Included are task definitions and initial progress in geologic disposal system studies, SURF compatibility, augmented heat dissipation, material qualification, exterior canister compatibility, ceramic liners for canisters, and geologic transport. Feasibility studies indicate that Kr-85 can be disposed of at SURF facility or in near-surface geologic repositories

  8. Nuclear reactions and application to production rates of krypton in extraterrestrial materials

    International Nuclear Information System (INIS)

    Lavielle, B.

    1982-01-01

    Noble gases have been largely outgassed from most solar system materials through several heating processes. Consequently, their cosmogenic component, produced by cosmic-ray-induced nuclear reactions near the surface of atmosphere-free planetary objects, is detectable in meteorites and lunar samples. This work deals with the production of cosmogenic Krypton in the four main targets Zr, Y, Sr and Rb. Excitation functions of Krypton isotopes with A = 78, 80, 81, 82, 83, 84, 85 and 86 were mass-spectrometrically measured in Y and Zr targets bombarded with 0.059, 0.075, 0.168, 0.200, 1.0, 2.5 and 24 GeV protons. Also the Krypton relative cross sections were measured in Sr at 0.168 GeV. The results, combined with a general survey of nuclear reactions in Ga to Nb targets, permitted the development of new systematics in order to estimate unknown cross-sections in Rb and Sr. Measured and estimated excitation functions allowed to calculate the concentrations and isotopic ratios of cosmogenic Krypton in same well-documented lunar samples. Compared to observed values in 9 rocks, 83 Kr is predicted with a precision better than 33% and the production ratios sup(i)Kr/ 83 Kr are predicted to better than 25%. Also it is concluded that the cosmogenic ratios 86 Kr/ 83 Kr and 81 Kr/ 83 Kr are dependent on the main target elements concentrations [fr

  9. The K Auger spectrum of krypton from the 83Rb decay

    International Nuclear Information System (INIS)

    Kovalik, A.; Gorozhankin, V.M.; Novgorodov, A.F.

    1990-01-01

    The K Auger spectrum of krypton was analyzed at the instrumental resolution of 6.5 eV using the evaporated 83 Rb source. The energies and relative intensities of the KLL-, KLX-, and KMX- Auger transitions were determined as well as the natural energy widths some of them. The results were compared with the theoretical predictions. 31 refs.; 3 figs.; 6 tabs

  10. An experimental study of the trapping and release of krypton in nickel

    International Nuclear Information System (INIS)

    Donnelly, S.E.; Ingram, D.C.; Armour, D.G.

    1979-01-01

    An experimental study is reported of the trapping and release of krypton implanted into nickel at low energies ( + incident on Ni (110) the maximum quantity of gas retained in the target was found to be approximately 2.5 x 10 15 ions cm -2 . (author)

  11. Phase transitions in the argon, krypton and xenon in generalized Van der Waals theory

    International Nuclear Information System (INIS)

    Cavalcanti, H.M.

    1977-01-01

    Fluid-solid like phase transitions for three monoatomic substances, argon, krypton and xenon are treated, using the extension of the Van der Waals theory to the crystalline state. The method utilized is based on 'Maxwell construction' of identical areas [pt

  12. Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake.

    Science.gov (United States)

    Deutzmann, Joerg S; Stief, Peter; Brandes, Josephin; Schink, Bernhard

    2014-12-23

    Anaerobic methane oxidation coupled to denitrification, also known as "nitrate/nitrite-dependent anaerobic methane oxidation" (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were very abundant at deep-water sites (profundal sediment). In profundal sediment, the vertical distribution of M. oxyfera-like bacteria showed a distinct peak in anoxic layers that coincided with the zone of methane oxidation and nitrate consumption, a strong indication for n-damo carried out by M. oxyfera-like bacteria. Both potential n-damo rates calculated from cell densities (660-4,890 µmol CH4⋅m(-2)⋅d(-1)) and actual rates calculated from microsensor profiles (31-437 µmol CH4⋅m(-2)⋅d(-1)) were sufficiently high to prevent methane release from profundal sediment solely by this process. Additionally, when nitrate was added to sediment cores exposed to anoxic conditions, the n-damo zone reestablished well below the sediment surface, completely preventing methane release from the sediment. We conclude that the previously overlooked n-damo process can be the major methane sink in stable freshwater environments if nitrate is available in anoxic zones.

  13. Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake

    Science.gov (United States)

    Deutzmann, Joerg S.; Stief, Peter; Brandes, Josephin; Schink, Bernhard

    2014-01-01

    Anaerobic methane oxidation coupled to denitrification, also known as “nitrate/nitrite-dependent anaerobic methane oxidation” (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were very abundant at deep-water sites (profundal sediment). In profundal sediment, the vertical distribution of M. oxyfera-like bacteria showed a distinct peak in anoxic layers that coincided with the zone of methane oxidation and nitrate consumption, a strong indication for n-damo carried out by M. oxyfera-like bacteria. Both potential n-damo rates calculated from cell densities (660–4,890 µmol CH4⋅m−2⋅d−1) and actual rates calculated from microsensor profiles (31–437 µmol CH4⋅m−2⋅d−1) were sufficiently high to prevent methane release from profundal sediment solely by this process. Additionally, when nitrate was added to sediment cores exposed to anoxic conditions, the n-damo zone reestablished well below the sediment surface, completely preventing methane release from the sediment. We conclude that the previously overlooked n-damo process can be the major methane sink in stable freshwater environments if nitrate is available in anoxic zones. PMID:25472842

  14. Radiometric titration of officinal radiopharmaceuticals using radioactive kryptonates as end-point indicators. I. Salicylic, acetylosalicylic, benzoic acids

    Energy Technology Data Exchange (ETDEWEB)

    Toelgyessy, J; Dillinger, P [Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia). Chemickotechnologicka Fakulta; Harangozo, M; Jombik, J [Komenskeho Univ., Bratislava (Czechoslovakia). Farmaceuticka Fakulta

    1980-01-01

    A method for the determination of salicylic, acetylsalicylic and benzoic acids in officinal pharmaceutical based on radiometric titration with 0.1 mol.l/sup -1/ NaOH was developed. The end-point was detected with the aid of radioactive glass kryptonate. After the end-point, the excess titrant attacks the glass surface layers and this results in releasing /sup 85/Kr, and consequently, in decreasing the radioactivity of the kryptonate employed. The radioactive kryptonate used as an indicator was prepared by the bombardment of glass with accelerated /sup 85/Kr ions. The developed method is simple, accurate and correct.

  15. Chemical Looping Combustion of Hematite Ore with Methane and Steam in a Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Samuel Bayham

    2017-08-01

    Full Text Available Chemical looping combustion is considered an indirect method of oxidizing a carbonaceous fuel, utilizing a metal oxide oxygen carrier to provide oxygen to the fuel. The advantage is the significantly reduced energy penalty for separating out the CO2 for reuse or sequestration in a carbon-constrained world. One of the major issues with chemical looping combustion is the cost of the oxygen carrier. Hematite ore is a proposed oxygen carrier due to its high strength and resistance to mechanical attrition, but its reactivity is rather poor compared to tailored oxygen carriers. This problem is further exacerbated by methane cracking, the subsequent deposition of carbon and the inability to transfer oxygen at a sufficient rate from the core of the particle to the surface for fuel conversion to CO2. Oxygen needs to be readily available at the surface to prevent methane cracking. The purpose of this work was to demonstrate the use of steam to overcome this issue and improve the conversion of the natural gas to CO2, as well as to provide data for computational fluid dynamics (CFD validation. The steam will gasify the deposited carbon to promote the methane conversion. This work studies the performance of hematite ore with methane and steam mixtures in a 5 cm fluidized bed up to approximately 140 kPa. Results show an increased conversion of methane in the presence of steam (from 20–45% without steam to 60–95% up to a certain point, where performance decreases. Adding steam allows the methane conversion to carbon dioxide to be similar to the overall methane conversion; it also helped to prevent carbon accumulation from occurring on the particle. In general, the addition of steam to the feed gas increased the methane conversion. Furthermore, the addition of steam caused the steam methane reforming reaction to form more hydrogen and carbon monoxide at higher steam and methane concentrations, which was not completely converted at higher concentrations and

  16. Combined gas-phase oxidation of methane and ethylene

    International Nuclear Information System (INIS)

    Pogosyan, N.M.; Pogosyan, M.D.

    2009-01-01

    It is established that depending on the reaction conditions combined oxidation of methane and ethylene may result in ethylene and propylene oxides with high selectivity with respect to the process, where in the initial reaction mixture methane is replaced by the same quantity of nitrogen. The formed additional methyl radicals increase the yield of all reaction products except CO. At low temperatures methyl radicals react with oxygen resulting in methyl peroxide radicals, which in turn, reacting with ethylene provide its epoxidation and formation of other oxygen-containing products. At high temperatures as a result of addition reaction between methyl radicals and ethylene, propyl radicals are formed that, in turn yield propylene. Alongside with positive influence on the yield of reaction products, methane exerts negative influence upon the conversion, that is it decreases the rate of ethylene and oxygen conversion, simultaneously decreasing significantly the yield of CO

  17. Dense ceramic membranes for methane conversion

    Energy Technology Data Exchange (ETDEWEB)

    Bouwmeester, Henny J.M. [Laboratory for Inorganic Materials Science, Department of Science and Technology and MESA Research Institute, University of Twente, 7500 AE Enschede (Netherlands)

    2003-07-30

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor, this technology is expected to significantly reduce the capital costs of conversion of natural gas to liquid added-value products. The present survey is mainly concerned with the material properties that govern the performance of the mixed-conducting membranes in real operating conditions and highlights significant developments in the field.

  18. Simulations of Atmospheric Krypton-85 to Assess the Detectability of Clandestine Nuclear Reprocessing

    International Nuclear Information System (INIS)

    Ross, O.; Ahlswede, J.; Annewandter, R.; Kalinowski, M.B.; Rast, S.; Schluenzen, K.H.

    2010-01-01

    The results of this study were achieved in the project 'Simulation of Atmospheric Noble Gas Concentrations to Assess Sampling Procedures for the Detection of Clandestine Nuclear Reprocessing' (IAEA GER 1643) in the joint programme of IAEA and Federal Government of Germany. In the first year of the project the detectability of additional krypton-85 sources was investigated using atmospheric transport modelling. Krypton-85 is released into the air during reprocessing of spent nuclear fuel rods. Therefore the krypton-85 signature can possibly be used for the detection of undeclared plutonium separation. First, the global krypton-85 background produced by known reprocessing facilities from 1971 until 2006 was simulated with the atmospheric general circulation model ECHAM5 using annual emission data. The model results were evaluated by extensive comparison with measurements performed by the German Federal Office for Radiation Protection. Of particular interest for an assessment of the detectability of unknown sources is the background variability. The variability of concentrations is very high over central Europe, where the large reprocessing plants La Hague and Sellafield are located, and it is very low on the Southern Hemisphere, where no nuclear reprocessing takes place. The analysis of concentration time series on various time scales allows partly a distinction between fluctuations caused by the variability of the sources from variations due to atmospheric dynamics. Furthermore the detection sensitivity to a set of arbitrarily specified source locations is analysed with a Lagrangian particle dispersion model. This, in combination with the location specific background variability, is giving first benchmarks on the capability of using krypton-85 for IAEA Safeguards based on the Additional Protocols foreseeing environmental sampling. (author)

  19. Immobilisation of krypton in a metallic matrix by combined ion implantation and sputtering

    International Nuclear Information System (INIS)

    Whitmell, D.S.

    1980-01-01

    With the increase in nuclear power, it may be necessary to contain for 100 to 200 years the radioactive 85 krypton released during fuel reprocessing. The ideal method of immobilising radioactive materials is in the form of stable, monolithic solids which are resistant to the effects of the environment or accidents, and which can retain the radioactivity under all envisaged conditions. Since krypton is a rare gas, not forming thermally stable compounds, conventional methods of storage are not possible. A process is being developed to immobilise the krypton in the form of small gas bubbles in a metal matrix by implanting the gas into a metal layer from a glow discharge and then burying the implanted layer by sputter deposition. By repeating the process, a thick layer of deposit is built up with the krypton dispersed throughout the matrix as bubbles of diameter less than 20 A. This process offers an ideal form of storage since gas in bubbles is not thermally released until the temperature of the matrix is close to the melting point, and also leakage of gas by corrosion or mechanical damage will be small. A pilot plant is being built in order to demonstrate the process on a scale comparable with that required for a reprocessing plant. The efficiency of the process is dependent upon the amount of gas which can be implanted at low energy into a thin layer and its subsequent retention. More information is required on the processes occurring when krypton ions are implanted close to the surface, in particular, the retention and re-emission of the gas, and the formation of clusters and bubbles. (author)

  20. Mechanics of coalbed methane production

    Energy Technology Data Exchange (ETDEWEB)

    Creel, J C; Rollins, J B [Crawley, Gillespie and Associates, Inc. (United Kingdom)

    1994-12-31

    Understanding the behaviour of coalbed methane reservoirs and the mechanics of production is crucial to successful management of coalbed methane resources and projects. This paper discusses the effects of coal properties and coalbed methane reservoir characteristics on gas production rates and recoveries with a review of completion techniques for coalbed methane wells. 4 refs., 17 figs.

  1. Analysis of Decomposition for Structure I Methane Hydrate by Molecular Dynamics Simulation

    Science.gov (United States)

    Wei, Na; Sun, Wan-Tong; Meng, Ying-Feng; Liu, An-Qi; Zhou, Shou-Wei; Guo, Ping; Fu, Qiang; Lv, Xin

    2018-05-01

    Under multi-nodes of temperatures and pressures, microscopic decomposition mechanisms of structure I methane hydrate in contact with bulk water molecules have been studied through LAMMPS software by molecular dynamics simulation. Simulation system consists of 482 methane molecules in hydrate and 3027 randomly distributed bulk water molecules. Through analyses of simulation results, decomposition number of hydrate cages, density of methane molecules, radial distribution function for oxygen atoms, mean square displacement and coefficient of diffusion of methane molecules have been studied. A significant result shows that structure I methane hydrate decomposes from hydrate-bulk water interface to hydrate interior. As temperature rises and pressure drops, the stabilization of hydrate will weaken, decomposition extent will go deep, and mean square displacement and coefficient of diffusion of methane molecules will increase. The studies can provide important meanings for the microscopic decomposition mechanisms analyses of methane hydrate.

  2. Reactions of O/1D/ with methane and ethane.

    Science.gov (United States)

    Lin, C.-L.; Demore, W. B.

    1973-01-01

    Mixtures of nitrous oxide and methane and mixtures of nitrous oxide and ethane were photolyzed with 1849-A light. The reaction products were analyzed chromatographically. It was found that the reaction of the excited atomic oxygen with methane gives mainly CH3 and OH radicals as initial products, along with about 9% of formaldehyde and molecular hydrogen. The reaction of the excited atomic oxygen with ethane gives C2H5, OH, CH3 and CH2OH as major initial products, with only a few per cent of molecular hydrogen.

  3. Methane monitoring from space

    Science.gov (United States)

    Stephan, C.; Alpers, M.; Millet, B.; Ehret, G.; Flamant, P.

    2017-11-01

    Methane is one of the strongest anthropogenic greenhouse gases. It contributes by its radiative forcing significantly to the global warming. For a better understanding of climate changes, it is necessary to apply precise space-based measurement techniques in order to obtain a global view on the complex processes that control the methane concentration in the atmosphere. The MERLIN mission is a joint French-German cooperation, on a micro satellite mission for space-based measurement of spatial and temporal gradients of atmospheric methane columns on a global scale. MERLIN will be the first Integrated Path Differential Absorption LIDAR for greenhouse gas monitoring from space. In contrast to passive methane missions, the LIDAR instrument allows measurements at alllatitudes, all-seasons and during night.

  4. Methane prediction in collieries

    CSIR Research Space (South Africa)

    Creedy, DP

    1999-06-01

    Full Text Available The primary aim of the project was to assess the current status of research on methane emission prediction for collieries in South Africa in comparison with methods used and advances achieved elsewhere in the world....

  5. Phytoremediation of Atmospheric Methane

    Science.gov (United States)

    2013-04-15

    REPORT Phytoremediation of Atmospheric Methane 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We have transformed a plant, Arabidopsis thaliana, with the...298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - 31-Mar-2012 Phytoremediation of Atmospheric Methane Report Title ABSTRACT We have transformed a...DD882) Scientific Progress See attachment Technology Transfer 1    Final Report for DARPA project W911NF1010027  Phytoremediation  of Atmospheric

  6. Terrestrial plant methane production

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Møller, Ian M.

    We evaluate all experimental work published on the phenomenon of aerobic methane (CH4) generation in terrestrial plants. We conclude that the phenomenon is true. Four stimulating factors have been observed to induce aerobic plant CH4 production, i.e. cutting injuries, increasing temperature...... the aerobic methane emission in plants. Future work is needed for establishing the relative contribution of several proven potential CH4 precursors in plant material....

  7. Methanation of Carbon Dioxide

    OpenAIRE

    Goodman, Daniel Jacob

    2013-01-01

    The emission of greenhouse gases into the atmosphere has been linked to global warming. Carbon dioxide's (CO2) one of the most abundant greenhouse gases. Natural gas, mainly methane, is the cleanest fossil fuel for electricity production helping meet the United States ever growing energy needs. The methanation of CO2 has the potential to address both of these problems if a catalyst can be developed that meets the activity, economic and environmental requirements to industrialize the process. ...

  8. Radiometric titration of officinal radiopharmaceuticals using radioactive kryptonates as end-point indicators. II. Citric, tartaric, undecylenic acids

    Energy Technology Data Exchange (ETDEWEB)

    Harangozo, M.; Jombik, J.; Schiller, P. (Komenskeho Univ., Bratislava (Czechoslovakia). Farmaceuticka Fakulta); Toelgyessy, J. (Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia). Chemickotechnologicka Fakulta)

    1981-01-01

    A method for the determination of citric, tartaric and undecylenic acids based on radiometric titration with 0.1 or 0.05 mole.l/sup -1/ NaOH was developed. As an indicator of the end point, radioactive kryptonate of glass was used. Experimental technique, results of determinations as well as other possible applications of the radioactive kryptonate of glass for end point determination in alkalimetric analyses of officinal pharmaceuticals are discussed.

  9. High-Pressure Reactivity of Kr and F2—Stabilization of Krypton in the +4 Oxidation State

    Directory of Open Access Journals (Sweden)

    Dominik Kurzydłowski

    2017-10-01

    Full Text Available Since the synthesis of the first krypton compound, several other Kr-bearing connections have been obtained. However, in all of them krypton adopts the +2 oxidation state, in contrast to xenon which forms numerous compounds with an oxidation state as high as +8. Motivated by the possibility of thermodynamic stabilization of exotic compounds with the use of high pressure (exceeding 1 GPa = 10 kbar, we present here theoretical investigations into the chemistry of krypton and fluorine at such large compression. In particular we focus on krypton tetrafluoride, KrF4, a molecular crystal in which krypton forms short covalent bonds with neighboring fluorine atoms thus adopting the +4 oxidation state. We find that this hitherto unknown compound can be stabilized at pressures below 50 GPa. Our results indicate also that, at larger compressions, a multitude of other KrmFn fluorides should be stable, among them KrF which exhibits covalent Kr–Kr bonds. Our results set the stage for future high-pressure synthesis of novel krypton compounds.

  10. Enrichment Conditions of Krypton Onto Activated Carbons%活性炭对氪的富集条件

    Institute of Scientific and Technical Information of China (English)

    陈莉云; 曾宝珠; 张昌云; 武山; 刘龙波; 杨静; 韦冠一

    2012-01-01

    In order to monitor radioactive krypton distribution in the environment, active charcoal is used to enrich krypton before the sample can be submitted to further laboratory analysis. The importance and method of krypton enrichment were presented. The absorption behavior of krypton by charcoal was analyzed. The experimental setup was designed to investigate effects of working temperature, linear velocities, partial-pressure of krypton on the enrichment of krypton by charcoal. The micro-structure parameters of the absorbing material to characterize its absorbing property was used, and the experimental data with theoretical analysis to conclude that for CF-1450 was fitted. The saturation absorption capacity at 191 K is 32. 9 mL/g.%从环境监测角度,叙述了开展活性炭对氪富集条件研究的重要意义.以氪在活性炭上的动态吸附实验为基础,研究了活性炭、温度、气体线流速和氪的分压对氪富集的影响,利用吸附材料的微结构,通过吸附理论模型拟合实验数据,得到CF-1450活性炭在191 K下对氪的饱和吸附量为32.9 mL/g.

  11. State-of-the-art ab initio potential energy curve for the krypton atom pair and thermophysical properties of dilute krypton gas.

    Science.gov (United States)

    Jäger, Benjamin; Hellmann, Robert; Bich, Eckard; Vogel, Eckhard

    2016-03-21

    A new reference krypton-krypton interatomic potential energy curve was developed by means of quantum-chemical ab initio calculations for 36 interatomic separations. Highly accurate values for the interaction energies at the complete basis set limit were obtained using the coupled-cluster method with single, double, and perturbative triple excitations as well as t-aug-cc-pV5Z and t-aug-cc-pV6Z basis sets including mid-bond functions, with the 6Z basis set being newly constructed for this study. Higher orders of coupled-cluster terms were considered in a successive scheme up to full quadruple excitations. Core-core and core-valence correlation effects were included. Furthermore, relativistic effects were studied not only at a scalar relativistic level using second-order direct perturbation theory, but also utilizing full four-component and Gaunt-effect computations. An analytical pair potential function was fitted to the interaction energies, which is characterized by a depth of 200.88 K with an estimated standard uncertainty of 0.51 K. Thermophysical properties of low-density krypton were calculated for temperatures up to 5000 K. Second and third virial coefficients were obtained from statistical thermodynamics. Viscosity and thermal conductivity as well as the self-diffusion coefficient were computed using the kinetic theory of gases. The theoretical results are compared with experimental data and with results for other pair potential functions from the literature, especially with those calculated from the recently developed ab initio potential of Waldrop et al. [J. Chem. Phys. 142, 204307 (2015)]. Highly accurate experimental viscosity data indicate that both the present ab initio pair potential and the one of Waldrop et al. can be regarded as reference potentials, even though the quantum-chemical methods and basis sets differ. However, the uncertainties of the present potential and of the derived properties are estimated to be considerably lower.

  12. Non Thermal Plasma Assisted Catalytic Reactor for CO2 Methanation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In situ production of methane as propellant and oxygen as life support consumables from the atmospheric CO2 and water on Mars is a key enabling technology required...

  13. Evidence of sulfate-dependent anaerobic methane oxidation... Wolfe & Wilkin data table vers 1

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data file (.csv) including data plotted in manuscript figures: methane and sulfate concentrations, and stable isotope data for carbon, hydrogen, sulfur, and oxygen....

  14. Atmospheric Ozone and Methane in a Changing Climate

    Directory of Open Access Journals (Sweden)

    Ivar S. A. Isaksen

    2014-07-01

    Full Text Available Ozone and methane are chemically active climate-forcing agents affected by climate–chemistry interactions in the atmosphere. Key chemical reactions and processes affecting ozone and methane are presented. It is shown that climate-chemistry interactions have a significant impact on the two compounds. Ozone, which is a secondary compound in the atmosphere, produced and broken down mainly in the troposphere and stratosphre through chemical reactions involving atomic oxygen (O, NOx compounds (NO, NO2, CO, hydrogen radicals (OH, HO2, volatile organic compounds (VOC and chlorine (Cl, ClO and bromine (Br, BrO. Ozone is broken down through changes in the atmospheric distribution of the afore mentioned compounds. Methane is a primary compound emitted from different sources (wetlands, rice production, livestock, mining, oil and gas production and landfills.Methane is broken down by the hydroxyl radical (OH. OH is significantly affected by methane emissions, defined by the feedback factor, currently estimated to be in the range 1.3 to 1.5, and increasing with increasing methane emission. Ozone and methane changes are affected by NOx emissions. While ozone in general increase with increases in NOx emission, methane is reduced, due to increases in OH. Several processes where current and future changes have implications for climate-chemistry interactions are identified. It is also shown that climatic changes through dynamic processes could have significant impact on the atmospheric chemical distribution of ozone and methane, as we can see through the impact of Quasi Biennial Oscillation (QBO. Modeling studies indicate that increases in ozone could be more pronounced toward the end of this century. Thawing permafrost could lead to important positive feedbacks in the climate system. Large amounts of organic material are stored in the upper layers of the permafrost in the yedoma deposits in Siberia, where 2 to 5% of the deposits could be organic material

  15. Oxygen Effects in Anaerobic Digestion

    Directory of Open Access Journals (Sweden)

    Deshai Botheju

    2009-10-01

    Full Text Available Interaction of free oxygen in bio-gasification is a sparsely studied area, apart from the common argument of oxygen being toxic and inhibitory for anaerobic micro-cultures. Some studies have, however, revealed increased solubilisation of organic matter in the presence of some free oxygen in anaerobic digestion. This article analyses these counterbalancing phenomena with a mathematical modelling approach using the widely accepted biochemical model ADM 1. Aerobic oxidation of soluble carbon and inhibition of obligatory anaerobic organisms are modelled using standard saturation type kinetics. Biomass dependent first order hydrolysis kinetics is used to relate the increased hydrolysis rate with oxygen induced increase in biomass growth. The amended model, ADM 1-Ox (oxygen, has 25 state variables and 22 biochemical processes, presented in matrix form. The computer aided simulation tool AQUASIM 2.1 is used to simulate the developed model. Simulation predictions are evaluated against experimental data obtained using a laboratory batch test array comprising miniature anaerobic bio-reactors of 100 ml total volume each, operated under different initial air headspaces giving rise to the different oxygen loading conditions. The reactors were initially fed with a glucose solution and incubated at 35 Celsius, for 563 hours. Under the oxygen load conditions of 22, 44 and 88 mg/L, the ADM1-Ox model simulations predicted the experimental methane potentials quite adequately. Both the experimental data and the simulations suggest a linear reduction of methane potential with respect to the increase in oxygen load within this range.

  16. Significance of dissolved methane in effluents of anaerobically ...

    Science.gov (United States)

    The need for energy efficient Domestic Wastewater (DWW) treatment is increasing annually with population growth and expanding global energy demand. Anaerobic treatment of low strength DWW produces methane which can be used to as an energy product. Temperature sensitivity, low removal efficiencies (Chemical Oxygen Demand (COD), Suspended Solids (SS), and Nutrients), alkalinity demand, and potential greenhouse gas (GHG) emissions have limited its application to warmer climates. Although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10–30 °C), lower temperatures increase methane solubility leading to increased energy losses in the form of dissolved methane in the effluent. Estimates of dissolved methane losses are typically based on concentrations calculated using Henry's Law but advection limitations can lead to supersaturation of methane between 1.34 and 6.9 times equilibrium concentrations and 11–100% of generated methane being lost in the effluent. In well mixed systems such as AnMBRs which use biogas sparging to control membrane fouling, actual concentrations approach equilibrium values. Non-porous membranes have been used to recover up to 92.6% of dissolved methane and well suited for degassing effluents of Upflow Anaerobic Sludge Blanket (UASB) reactors which have considerable solids and organic contents and can cause pore wetting and clogging in microporous membrane modules. Micro

  17. Coalbed methane: new frontier

    Energy Technology Data Exchange (ETDEWEB)

    Eaton, S.

    2003-02-01

    There are large numbers of stacked coal seams permeated with methane or natural gas in the Western Canadian Sedimentary Basin, and approximately 20 coalbed methane pilot projects are operating in the area, and brief descriptions of some of them were provided. Coalbed methane reserves have a long life cycle. A definition of coalbed methane can be a permeability challenged reservoir. It is not uncommon for coalbed methane wells to flow water for periods varying from 2 to 6 months after completion before the production of natural gas. A made-in-Canada technological solution is being developed by CDX Canada Inc., along with its American parent company. The techniques used by CDX are a marriage between coal mining techniques and oil and gas techniques. A brief description of coalification was provided. Nexen is participating in the production of gas from an Upper Mannville coal at 1 000-metres depth in a nine-well pilot project. The Alberta Foothills are considered prime exploration area since older coal is carried close to the surface by thrusting. CDX Canada uses cavitation completion in vertical wells. Cavitation consists in setting the casing above the coal seam and drilling ahead under balanced. The design of wells for coalbed methane gas is based on rock and fluid mechanics. Hydraulic fracturing completions is also used, as are tiltmeters. An enhanced coalbed methane recovery pilot project is being conducted by the Alberta Research Council at Fenn-Big Valley, located in central Alberta. It injects carbon dioxide, which shows great potential for the reduction of greenhouse gas emissions. 1 figs.

  18. Experimental studies on the krypton absorption in liquid CO2 (KALC) process

    International Nuclear Information System (INIS)

    Glass, R.W.; Beaujean, H.W.R.; Fowler, V.L.; Gilliam, T.M.; Inman, D.J.; Levins, D.M.

    1976-01-01

    Results are presented for a series of experiments to quantify krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing off-gas by the KALC process. The Experimental Engineering Section Off-Gas Decontamination Facility used in the campaign provides engineering-scale experiments with nominal gas and liquid flows of 5 scfm and 0.5 gpm respectively. Equilibrium and nonequilibrium mass transfer experiments for the CO 2 --O 2 --Kr system are described. Data analysis indicates values of HTU for krypton on the order of 0.5 ft for decontamination factors from 100 to 10,000. Recent flooding information for the packed columns is combined with previous data and is shown to be well represented by an empirical flooding equation

  19. S-process krypton of variable isotopic composition in the Murchison meteorite

    Science.gov (United States)

    Ott, Urlich; Begemann, Friedrich; Yang, Yongmann; Epstein, Samuel

    1988-01-01

    Data are reported which, for the first time, permit the derivation of the full isotopic spectrum of s-process krypton with reasonable precision. It is shown that this s-Kr in a residue from the Murchison meteorite did not originate in one single s-process but rather is a mixture of contributions from stellar environments where the density of free neutrons was not the same. The astrophysical conditions under which this krypton was produced were distinct from those that have been invoked to explain the solar system s-process abundance. Similar to the C-13-rich carbon component in an aliquot of the same residue, the s-process Kr from different astrophysical sites has retained its identity during the accumulation and subsequent history of the meteorite.

  20. AA stacking, tribological and electronic properties of double-layer graphene with krypton spacer.

    Science.gov (United States)

    Popov, Andrey M; Lebedeva, Irina V; Knizhnik, Andrey A; Lozovik, Yurii E; Potapkin, Boris V; Poklonski, Nikolai A; Siahlo, Andrei I; Vyrko, Sergey A

    2013-10-21

    Structural, energetic, and tribological characteristics of double-layer graphene with commensurate and incommensurate krypton spacers of nearly monolayer coverage are studied within the van der Waals-corrected density functional theory. It is shown that when the spacer is in the commensurate phase, the graphene layers have the AA stacking. For this phase, the barriers to relative in-plane translational and rotational motion and the shear mode frequency of the graphene layers are calculated. For the incommensurate phase, both of the barriers are found to be negligibly small. A considerable change of tunneling conductance between the graphene layers separated by the commensurate krypton spacer at their relative subangstrom displacement is revealed by the use of the Bardeen method. The possibility of nanoelectromechanical systems based on the studied tribological and electronic properties of the considered heterostructures is discussed.

  1. S-process krypton of variable isotopic composition in the Murchison meteorite

    International Nuclear Information System (INIS)

    Ott, U.; Begemann, F.; Yang, J.; Epstein, S.

    1988-01-01

    We report data that allow us to derive with reasonable precision the full isotopic spectrum of s-process krypton. We show that this s-Kr in a residue from Murchison meteorite did not originate in one single s-process but rather is a mixture of contributions from stellar environments where the density of free neutrons was not the same. The astrophysical conditions under which this krypton has been produced were distinct from those that have been invoked to explain the Solar System s-process abundance. Similar to the 13 C-rich carbon component in an aliquot of the same residue, the s-process Kr from different astrophysical sites has retained its identify during the accumulation and subsequent history of the meteorite. (author)

  2. Kilo-electron-volt neutron capture cross sections of the krypton isotopes

    International Nuclear Information System (INIS)

    Walter, G.; Leugers, B.; Kappeler; Bao, Z.Y.; Reffo, G.; Fabbri, F.

    1986-01-01

    The neutron capture cross sections of the stable krypton isotopes were determined in the energy interval from 4 to 250 keV using a C/sub 6/D/sub 6/-detector system in conjunction with the time-of-flight technique. The energy resolution of the measurement was 4% at 20 keV and 6% at 100 keV, and the experimental uncertainties were typically 6 to 10%. The measurements were complemented by statistical model calculations of all krypton isotopes in the mass range 78 < A < 86 to also obtain reliable cross sections for the unstable nuclei /sup 79,81,85/Kr. These calculations were based on local systematics for all relevant parameters, and the results were estimated to show uncertainties of 20 to 25%. Maxwellian average cross sections were calculated for kT=30 keV

  3. Photochemistry of the ozone-water complex in cryogenic neon, argon, and krypton matrixes.

    Science.gov (United States)

    Tsuge, Masashi; Tsuji, Kazuhide; Kawai, Akio; Shibuya, Kazuhiko

    2013-12-12

    The photochemistry of ozone-water complexes and the wavelength dependence of the reactions were studied by matrix isolation FTIR spectrometry in neon, argon, and krypton matrixes. Hydrogen peroxide was formed upon the irradiation of UV light below 355 nm. Quantitative analyses of the reactant and product were performed to evaluate the matrix cage effect of the photoreaction. In argon and krypton matrixes, a bimolecular O((1)D) + H2O → H2O2 reaction was found to occur to form hydrogen peroxide, where the O((1)D) atom generated by the photolysis of ozone diffused in the cryogenic solids to encounter water. In a neon matrix, hydrogen peroxide was generated through intracage photoreaction of the ozone-water complex, indicating that a neon matrix medium is most appropriate to study the photochemistry of the ozone-water complex.

  4. Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure

    Science.gov (United States)

    Barr, G. D.; Bruschini, C.; Bocquet, C.; Buchholz, P.; Cundy, D.; Doble, N.; Funk, W.; Gatignon, L.; Gonidec, A.; Hallgren, B.; Kesseler, G.; Lacourt, A.; Laverrière, G.; Linser, G.; Martini, M.; Norton, A.; Schinzel, D.; Seidl, W.; Sozzi, M. S.; Taureg, H.; Vossnack, O.; Wahl, H.; Wertelaers, P.; Weterings, J.; Ziolkowski, M.; Kalinin, A.; Kekelidze, V.; Kozhevnikov, Yu.; Bertolotto, L.; Carassiti, V.; Duclos, J.; Gianoli, A.; Frabetti, P. L.; Savriè, M.; Zeitnitz, O.; Calvetti, M.; Lubrano, P.; Pepe, M.; Calafiura, P.; Cerri, C.; Costantini, F.; Fantechi, R.; Gorini, B.; Mannelli, I.; Marzulli, V.; Bédérède, D.; Debu, P.; Givernaud, A.; Gosset, L.; Heitzmann, J.; Mazzucato, E.; Peyaud, B.; Turlay, R.; Biino, C.; Ceccucci, A.; Maas, P.; Palestini, S.; Cagliari-Cambridge-CERN-Dubna-Edinburgh-Ferrara-Mainz-Orsay-Perugia-Pisa-Saclay-Siegen-Torino-Vienna Collaboration

    1996-02-01

    The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K 0- overlineK 0 system with an accuracy of 2 × 10 -4 in the parameter Re(ɛ'/ɛ). Decays in two π0's will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of {≃3.5%}/{√E} with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV.

  5. Removing krypton from xenon by cryogenic distillation to the ppq level

    Science.gov (United States)

    Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; Di Gangi, P.; Di Giovanni, A.; Diglio, S.; Duchovni, E.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Franco, D.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Grandi, L.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Huhmann, C.; Itay, R.; Kaminsky, B.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Calloch, M. Le; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Manfredini, A.; Maris, I.; Undagoitia, T. Marrodán; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Meng, Y.; Messina, M.; Micheneau, K.; Miguez, B.; Molinario, A.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Piro, M.-C.; Pizzella, V.; Plante, G.; Priel, N.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rosendahl, S.; Rupp, N.; Saldanha, R.; Santos, J. M. F. dos; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Lavina, L. Scotto; Selvi, M.; Shagin, P.; Shockley, E.; Silva, M.; Simgen, H.; Sivers, M. v.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Upole, N.; Wang, H.; Wei, Y.; Weinheimer, C.; Wulf, J.; Ye, J.; Zhang, Y.; Cristescu, I.

    2017-05-01

    The XENON1T experiment aims for the direct detection of dark matter in a detector filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. One major contributor is the β -emitter ^{85}Kr which is present in the xenon. For XENON1T a concentration of natural krypton in xenon ^{nat}Kr/Xe McCabe-Thiele approach is described. The system demonstrated a krypton reduction factor of 6.4\\cdot 10^5 with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of ^{nat}Kr/Xe<26 ppq is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN.

  6. Carbon dioxide-krypton separation and radon removal from nuclear-fuel-reprocessing off-gas streams

    International Nuclear Information System (INIS)

    Hirsch, P.M.; Higuchi, K.Y.; Abraham, L.

    1982-07-01

    General Atomic Company (GA) is conducting pilot-plant-scale tests that simulate the treatment of radioactive and other noxious volatile and gaseous constituents of off-gas streams from nuclear reprocessing plants. This paper reports the results of engineering-scale tests performed on the CO 2 /krypton separation and radon holdup/decay subsystems of the GA integrated off-gas treatment system. Separation of CO 2 from krypton-containing gas streams is necessary to facilitate subsequent waste processing and krypton storage. Molecular sieve 5A achieved this separation in dissolver off-gas streams containing relatively low krypton and CO 2 concentrations and in krypton-rich product streams from processes such as the krypton absorption in liquid carbon dioxide (KALC) process. The CO 2 /krypton separation unit is a 30.5-cm-diameter x 1.8-m-long column containing molecular sieve 5A. The loading capacity for CO 2 was determined for gas mixtures containing 250 ppM to 2.2% CO 2 and 170 to 750 ppM krypton in either N 2 or air. Gas streams rich in CO 2 were diluted with N 2 to reduce the temperature rise from the heat of adsorption, which would otherwise affect loading capacity. The effluent CO 2 concentration prior to breakthrough was less than 10 ppM, and the adsorption capacity for krypton was negligible. Krypton was monitored on-line with a time-of-flight mass spectrometer and its concentration determined quantitatively by a method of continuous analysis, i.e., selected-ion monitoring. Radon-220 was treated by holdup and decay on a column of synthetic H-mordenite. The Rn-220 concentration was monitored on-line with flow-through diffused-junction alpha detectors. Single-channel analyzers were utilized to isolate the 6.287-MeV alpha energy band characteristic of Rn-220 decay from energy bands due to daughter products

  7. Destruction of fast H(2S) atoms in collisions with neon, krypton, xenon, and molecular hydrogen

    International Nuclear Information System (INIS)

    Roussel, F.; Pradel, P.; Spiess, G.

    1977-01-01

    Measurements are reported for the total quenching of metastable hydrogen atoms by neon, krypton, xenon, and molecular hydrogen, in the energy range 0.052--3 keV. The cross sections are found to be on the order of 5 x 10 -15 cm 2 at the lowest energies, and decrease to approximately 2 x 10 -15 cm 2 at the highest energies. The data at low energy are analyzed using a simple theoretical model

  8. Purification of cyclotron-produced 81Rb for the preparation of small krypton-81m generators

    International Nuclear Information System (INIS)

    Andersen, P.; Haasbroek, F.J.; Venter, S.S.J.; Strelow, F.W.E.

    1981-01-01

    A method is described for the separation of 81 Rb from sodium bromide targets. Ammonium molybdophosphate columns are used and the separation takes only about 20 minutes. More than 90% of the 81 Rb is recovered. The purified 81 Rb enables small Rubidium-81/Krypton-81m generators to be prepared with Bio-Rad 50W-X8 ion-exchange resin (200-400 mesh) [af

  9. Effect of flow rate on the adsorption coefficient of radioactive krypton on activated carbon

    International Nuclear Information System (INIS)

    Sun, L.S.C.; Underhill, D.W.

    1981-01-01

    For some time, there have been questions relative to the effect of carrier gas velocity on the adsorption coefficient for radioactive noble gases on activated charcoal. Resolution of these questions is particularly important in terms of developing standard procedures for determining such coefficients under laboratory conditions. Studies at the Harvard Air Cleaning Laboratory appear to confirm that the adsorption coefficient for radioactive krypton on activated charcoal is independent of the velocity of the carrier gas

  10. Adsorption and pore condensation of krypton on mesoporous silicas at 77 K

    Czech Academy of Sciences Publication Activity Database

    Zukal, Arnošt

    2006-01-01

    Roč. 92, 1-3 (2006), s. 220-226 ISSN 1387-1811 R&D Projects: GA ČR GA203/05/0197; GA MPO FT-TA/040 Institutional research plan: CEZ:AV0Z40400503 Keywords : adsorption of krypton at 77 K * capillary condensation * stability condition * restriction of mesopore filling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.796, year: 2006

  11. Thermophysical properties of krypton-helium gas mixtures from ab initio pair potentials.

    Science.gov (United States)

    Jäger, Benjamin; Bich, Eckard

    2017-06-07

    A new potential energy curve for the krypton-helium atom pair was developed using supermolecular ab initio computations for 34 interatomic distances. Values for the interaction energies at the complete basis set limit were obtained from calculations with the coupled-cluster method with single, double, and perturbative triple excitations and correlation consistent basis sets up to sextuple-zeta quality augmented with mid-bond functions. Higher-order coupled-cluster excitations up to the full quadruple level were accounted for in a scheme of successive correction terms. Core-core and core-valence correlation effects were included. Relativistic corrections were considered not only at the scalar relativistic level but also using full four-component Dirac-Coulomb and Dirac-Coulomb-Gaunt calculations. The fitted analytical pair potential function is characterized by a well depth of 31.42 K with an estimated standard uncertainty of 0.08 K. Statistical thermodynamics was applied to compute the krypton-helium cross second virial coefficients. The results show a very good agreement with the best experimental data. Kinetic theory calculations based on classical and quantum-mechanical approaches for the underlying collision dynamics were utilized to compute the transport properties of krypton-helium mixtures in the dilute-gas limit for a large temperature range. The results were analyzed with respect to the orders of approximation of kinetic theory and compared with experimental data. Especially the data for the binary diffusion coefficient confirm the predictive quality of the new potential. Furthermore, inconsistencies between two empirical pair potential functions for the krypton-helium system from the literature could be resolved.

  12. Self-compression of femtosecond deep-ultraviolet pulses by filamentation in krypton.

    Science.gov (United States)

    Adachi, Shunsuke; Suzuki, Toshinori

    2017-05-15

    We demonstrate self-compression of deep-ultraviolet (DUV) pulses by filamentation in krypton. In contrast to self-compression in the near-infrared, that in the DUV is associated with a red-shifted sub-pulse appearing in the pulse temporal profile. The achieved pulse width of 15 fs is the shortest among demonstrated sub-mJ deep-ultraviolet pulses.

  13. High-Power Krypton Hall Thruster Technology Being Developed for Nuclear-Powered Applications

    Science.gov (United States)

    Jacobson, David T.; Manzella, David H.

    2004-01-01

    The NASA Glenn Research Center has been performing research and development of moderate specific impulse, xenon-fueled, high-power Hall thrusters for potential solar electric propulsion applications. These applications include Mars missions, reusable tugs for low-Earth-orbit to geosynchronous-Earth-orbit transportation, and missions that require transportation to libration points. This research and development effort resulted in the design and fabrication of the NASA-457M Hall thruster that has been tested at input powers up to 95 kW. During project year 2003, NASA established Project Prometheus to develop technology in the areas of nuclear power and propulsion, which are enabling for deep-space science missions. One of the Project-Prometheus-sponsored Nuclear Propulsion Research tasks is to investigate alternate propellants for high-power Hall thruster electric propulsion. The motivation for alternate propellants includes the disadvantageous cost and availability of xenon propellant for extremely large scale, xenon-fueled propulsion systems and the potential system performance benefits of using alternate propellants. The alternate propellant krypton was investigated because of its low cost relative to xenon. Krypton propellant also has potential performance benefits for deep-space missions because the theoretical specific impulse for a given voltage is 20 percent higher than for xenon because of krypton's lower molecular weight. During project year 2003, the performance of the high-power NASA-457M Hall thruster was measured using krypton as the propellant at power levels ranging from 6.4 to 72.5 kW. The thrust produced ranged from 0.3 to 2.5 N at a discharge specific impulse up to 4500 sec.

  14. Encapsulation of krypton-85 in zeolite molecular sieve with a hot isostatic press

    International Nuclear Information System (INIS)

    Christensen, A.B.; DelDebbio, J.A.; Knecht, D.A.; Tanner, J.E.

    1986-01-01

    This paper describes pilot and full-scale experiments which demonstrated the feasibility of immobilizing Kr-85 in a zeolite 5A/glass mixture and compacting it before disposal. The full volume of a one-liter hot isostatic press (HIP) was used to trap argon in zeolite 5A. For radioactive krypton the HIP was modified to isolate the Kr-85 in the work zone. Details of the HIP modifications, experimental procedure, and sample analysis are reported

  15. Identification of krypton Kr XVIII to Kr XXIX spectra excited in TFR Tokamak plasmas

    International Nuclear Information System (INIS)

    Wyart, J.F.

    1985-02-01

    The emission spectrum of krypton (injected into TFR tokamak plasmas) has been recorded photographically in the 15-300 A spectral range by means of a 2m grazing incidence spectrograph. Preliminary identification work, based on isoelectronic regularities from known spectra of other ions and ionization equilibrium calculations, has allowed 48 lines (belonging to the O I, F I, Na I, Mg I, Al I, Ar I and K I sequences) to be identified

  16. Study on the possibility of sea-disposal of krypton-85

    International Nuclear Information System (INIS)

    Dalen, A. van; Vons, L.H.; Verkerk, B.

    1980-01-01

    Results of a feasibility study, performed under a contract with the Commission of the European Communities, regarding technical and radiological aspects of sea-disposal of all krypton-85 retained in a large fuel reprocessing facility, are presented. The design of a double-walled, essentially spherical container is described that provides both double containment of the compressed gas and permanent 'disposable' radiation shielding. Three sizes have been studied, i.e. with internal volumes of 0.01, 0.05 and 0.1 m 3 , each designed to hold 0.1 m 3 (STP) of krypton, and each containing approximately 400 TBq of 85 Kr per 0.001 m 3 sphere volume. This results in an internal heat production of 17.5 kW/m 3 . Calculations of temperatures and stresses that would result from the conditions of the required fire test for B(U) transport packages showed that the design would allow the containers to pass this test. Radiological consequences have been considered for disposal of petabecquerel amounts of 85 Kr as a function of undamaged container lifetime on the sea bed. Finally, an indication is given of the necessary amendments to the London Convention in order to allow sea-disposal of these large amounts of radioactive krypton. (author)

  17. Dynamic-Stability Characteristics of Premixed Methane Oxy-Combustion

    KAUST Repository

    Shroll, Andrew P.; Shanbhogue, Santosh J.; Ghoniem, Ahmed F.

    2012-01-01

    This work explores the dynamic stability characteristics of premixed CH 4/O 2/CO 2 mixtures in a 50 kW swirl stabilized combustor. In all cases, the methane-oxygen mixture is stoichiometric, with different dilution levels of carbon dioxide used

  18. Methane of the coal

    International Nuclear Information System (INIS)

    Vasquez, H.

    1997-01-01

    In the transformation process of the vegetable material to the coal (Carbonization), the products that are generated include CH 4, CO2, N2 and H2. The methane is generated by two mechanisms: below 50 centigrade degree, as product of microbial decomposition, the methanogenic is generated; and above 50 centigrade degree, due to the effects of the buried and increase of the range of the coal, the thermogenic methane is detachment, as a result of the catagenic. The generated methane is stored in the internal surfaces of the coal, macro and micro pores and in the natural fractures. The presence of accumulations of gas of the coal has been known in the entire world by many years, but only as something undesirable for its danger in the mining exploitation of the coal

  19. Comparison in the analytical performance between krypton and argon glow discharge plasmas as the excitation source for atomic emission spectrometry.

    Science.gov (United States)

    Wagatsuma, Kazuaki

    2009-04-01

    The emission characteristics of ionic lines of nickel, cobalt, and vanadium were investigated when argon or krypton was employed as the plasma gas in glow discharge optical emission spectrometry. A dc Grimm-style lamp was employed as the excitation source. Detection limits of the ionic lines in each iron-matrix alloy sample were compared between the krypton and the argon plasmas. Particular intense ionic lines were observed in the emission spectra as a function of the discharge gas (krypton or argon), such as the Co II 258.033 nm for krypton and the Co II 231.707 nm for argon. The explanation for this is that collisions with the plasma gases dominantly populate particular excited levels of cobalt ion, which can receive the internal energy from each gas ion selectively, for example, the 3d(7)4p (3)G(5) (6.0201 eV) for krypton and the 3d(7)4p (3)G(4) (8.0779 eV) for argon. In the determination of nickel as well as cobalt in iron-matrix samples, more sensitive ionic lines could be found in the krypton plasma rather than the argon plasma. Detection limits in the krypton plasma were 0.0039 mass% Ni for the Ni II 230.299-nm line and 0.002 mass% Co for the Co II 258.033-nm line. However, in the determination of vanadium, the argon plasma had better analytical performance, giving a detection limit of 0.0023 mass% V for the V II 309.310-nm line.

  20. Catalytic aromatization of methane.

    Science.gov (United States)

    Spivey, James J; Hutchings, Graham

    2014-02-07

    Recent developments in natural gas production technology have led to lower prices for methane and renewed interest in converting methane to higher value products. Processes such as those based on syngas from methane reforming are being investigated. Another option is methane aromatization, which produces benzene and hydrogen: 6CH4(g) → C6H6(g) + 9H2(g) ΔG°(r) = +433 kJ mol(-1) ΔH°(r) = +531 kJ mol(-1). Thermodynamic calculations for this reaction show that benzene formation is insignificant below ∼600 °C, and that the formation of solid carbon [C(s)] is thermodynamically favored at temperatures above ∼300 °C. Benzene formation is insignificant at all temperatures up to 1000 °C when C(s) is included in the calculation of equilibrium composition. Interestingly, the thermodynamic limitation on benzene formation can be minimized by the addition of alkanes/alkenes to the methane feed. By far the most widely studied catalysts for this reaction are Mo/HZSM-5 and Mo/MCM-22. Benzene selectivities are generally between 60 and 80% at methane conversions of ∼10%, corresponding to net benzene yields of less than 10%. Major byproducts include lower molecular weight hydrocarbons and higher molecular weight substituted aromatics. However, carbon formation is inevitable, but the experimental findings show this can be kinetically limited by the use of H2 or oxidants in the feed, including CO2 or steam. A number of reactor configurations involving regeneration of the carbon-containing catalyst have been developed with the goal of minimizing the cost of regeneration of the catalyst once deactivated by carbon deposition. In this tutorial review we discuss the thermodynamics of this process, the catalysts used and the potential reactor configurations that can be applied.

  1. Mixed oxygen ion/electron-conducting ceramics for oxygen separation

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-08-01

    Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.

  2. Direct Activation Of Methane

    KAUST Repository

    Basset, Jean-Marie

    2013-07-15

    Heteropolyacids (HPAs) can activate methane at ambient temperature (e.g., 20.degree. C.) and atmospheric pressure, and transform methane to acetic acid, in the absence of any noble metal such as Pd). The HPAs can be, for example, those with Keggin structure: H.sub.4SiW.sub.12O.sub.40, H.sub.3PW.sub.12O.sub.40, H.sub.4SiMo.sub.12O.sub.40, or H.sub.3PMo.sub.12O.sub.40, can be when supported on silica.

  3. Methanization - Technical sheet

    International Nuclear Information System (INIS)

    Bastide, Guillaume

    2015-02-01

    This document explains fundamentals of methanization such as biological reactions and conditions suitable for biogas production (temperature, pH, anaerobic medium, and so on). It also proposes an overview of available techniques, of the present regulation, of environmental impacts, and of costs and profitability of methanization installations. Examples of installations are provided, as well as a set of questions and answers. Perspectives of development are finally discussed in terms of sector development potential, of regulatory evolution, of new perspectives for gas valorisation, of need of acquisition of reference data due to the relatively low number of existing installations, and of research and development

  4. Australian methane fluxes

    International Nuclear Information System (INIS)

    Williams, D.J.

    1990-01-01

    Estimates are provided for the amount of methane emitted annually into the atmosphere in Australia for a variety of sources. The sources considered are coal mining, landfill, motor vehicles, natural gas suply system, rice paddies, bushfires, termites, wetland and animals. This assessment indicates that the major sources of methane are natural or agricultural in nature and therefore offer little scope for reduction. Nevertheless the remainder are not trival and reduction of these fluxes could play a significant part in any Australian action on the greenhouse problem. 19 refs., 7 tabs., 1 fig

  5. Methane oxidation in anoxic lake waters

    Science.gov (United States)

    Su, Guangyi; Zopfi, Jakob; Niemann, Helge; Lehmann, Moritz

    2017-04-01

    Freshwater habitats such as lakes are important sources of methante (CH4), however, most studies in lacustrine environments so far provided evidence for aerobic methane oxidation only, and little is known about the importance of anaerobic oxidation of CH4 (AOM) in anoxic lake waters. In marine environments, sulfate reduction coupled to AOM by archaea has been recognized as important sinks of CH4. More recently, the discorvery of anaerobic methane oxidizing denitrifying bacteria represents a novel and possible alternative AOM pathway, involving reactive nitrogen species (e.g., nitrate and nitrite) as electron acceptors in the absence of oxygen. We investigate anaerobic methane oxidation in the water column of two hydrochemically contrasting sites in Lake Lugano, Switzerland. The South Basin displays seasonal stratification, the development of a benthic nepheloid layer and anoxia during summer and fall. The North Basin is permanently stratified with anoxic conditions below 115m water depth. Both Basins accumulate seasonally (South Basin) or permanently (North Basin) large amounts of CH4 in the water column below the chemocline, providing ideal conditions for methanotrophic microorganisms. Previous work revealed a high potential for aerobic methane oxidation within the anoxic water column, but no evidence for true AOM. Here, we show depth distribution data of dissolved CH4, methane oxidation rates and nutrients at both sites. In addition, we performed high resolution phylogenetic analyses of microbial community structures and conducted radio-label incubation experiments with concentrated biomass from anoxic waters and potential alternative electron acceptor additions (nitrate, nitrite and sulfate). First results from the unamended experiments revealed maximum activity of methane oxidation below the redoxcline in both basins. While the incubation experiments neither provided clear evidence for NOx- nor sulfate-dependent AOM, the phylogenetic analysis revealed the

  6. Process for producing ethane and/or ethylene from methane. Verfahren zur Herstellung von Ethan und bzw. oder Ethylen aus Methan

    Energy Technology Data Exchange (ETDEWEB)

    Baerns, M.; Hinsen, W.

    1984-04-12

    According to the invention, methane is converted into hydrocarbons with oxygen with high selectivity. This is done in the presence of a catalyst fluidized in a fluidized bed - preferably lead oxide or a mixture of this with antimony oxide - at temperatures between 600 and 800/sup 0/C and at oxygen partial pressures preferably below 0.1-0.2 bar. The ratio of methane partial pressure to oxygen partial pressure should be greater than 2 to 5 if possible. The reactor is operated with gas feedback, in order to raise the selectivity even more.

  7. Permafrost slowly exhales methane

    Science.gov (United States)

    Herndon, Elizabeth M.

    2018-04-01

    Permafrost soils store vast quantities of organic matter that are vulnerable to decomposition under a warming climate. Recent research finds that methane release from thawing permafrost may outpace carbon dioxide as a major contributor to global warming over the next century.

  8. Methane pellet moderator development

    International Nuclear Information System (INIS)

    Foster, C.A.; Schechter, D.E.; Carpenter, J.M.

    2004-01-01

    A methane pellet moderator assembly consisting of a pelletizer, a helium cooled sub-cooling tunnel, a liquid helium cooled cryogenic pellet storage hopper and a 1.5L moderator cell has been constructed for the purpose demonstrating a system for use in high-power spallation sources. (orig.)

  9. Methane emissions from grasslands

    NARCIS (Netherlands)

    Pol - van Dasselaar, van den A.

    1998-01-01

    Introduction

    Methane (CH 4 ) is an important greenhouse gas. The concentration of greenhouse gases in the atmosphere has been increasing since pre-industrial times, mainly due to human activities. This increase gives concern,

  10. Direct Aromaization of Methane

    Energy Technology Data Exchange (ETDEWEB)

    George Marcelin

    1997-01-15

    The thermal decomposition of methane offers significant potential as a means of producing higher unsaturated and aromatic hydrocarbons when the extent of reaction is limited. Work in the literature previous to this project had shown that cooling the product and reacting gases as the reaction proceeds would significantly reduce or eliminate the formation of solid carbon or heavier (Clo+) materials. This project studied the effect and optimization of the quenching process as a means of increasing the amount of value added products during the pyrolysis of methane. A reactor was designed to rapidly quench the free-radical combustion reaction so as to maximize the yield of aromatics. The use of free-radical generators and catalysts were studied as a means of lowering the reaction temperature. A lower reaction temperature would have the benefits of more rapid quenching as well as a more feasible commercial process due to savings realized in energy and material of construction costs. It was the goal of the project to identify promising routes from methane to higher hydrocarbons based on the pyrolysis of methane.

  11. Simultaneous detection of xenon and krypton in equine plasma by gas chromatography-tandem mass spectrometry for doping control.

    Science.gov (United States)

    Kwok, Wai Him; Choi, Timmy L S; So, Pui-Kin; Yao, Zhong-Ping; Wan, Terence S M

    2017-02-01

    Xenon can activate the hypoxia-inducible factors (HIFs). As such, it has been allegedly used in human sports for increasing erythropoiesis. Krypton, another noble gas with reported narcosis effect, can also be expected to be a potential and less expensive erythropoiesis stimulating agent. This has raised concern about the misuse of noble gases as doping agents in equine sports. The aim of the present study is to establish a method for the simultaneous detection of xenon and krypton in equine plasma for the purpose of doping control. Xenon- or krypton-fortified equine plasma samples were prepared according to reported protocols. The target noble gases were simultaneously detected by gas chromatography-triple quadrupole mass spectrometry using headspace injection. Three xenon isotopes at m/z 129, 131, and 132, and four krypton isotopes at m/z 82, 83, 84, and 86 were targeted in selected reaction monitoring mode (with the precursor ions and product ions at identical mass settings), allowing unambiguous identification of the target analytes. Limits of detection for xenon and krypton were about 19 pmol/mL and 98 pmol/mL, respectively. Precision for both analytes was less than 15%. The method has good specificity as background analyte signals were not observed in negative equine plasma samples (n = 73). Loss of analytes under different storage temperatures has also been evaluated. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Present and future potential of krypton-85 for the detection of clandestine reprocessing plants for treaty verification.

    Science.gov (United States)

    Schoeppner, Michael; Glaser, Alexander

    2016-10-01

    Burnup calculations are applied to determine the amount of krypton-85 that is produced during the irradiation of nuclear fuel. Since krypton-85 is most likely released into the atmosphere during reprocessing to separate plutonium, atmospheric transport modeling is used to calculate the worldwide distribution of krypton-85 concentrations stemming from emissions from declared reprocessing plants. The results are the basis for scenarios in which emissions from clandestine reprocessing facilities have to be detected against various background levels. It is concluded that today's background imposes heavily on the ability to detect small and medium plutonium separation rates; only high separation rates of 1 SQ per week and higher have a chance to be detected with feasible outlay. A fixed network of monitoring stations seems too costly; instead the high number of samples that are required rather calls for mobile sampling procedures, where air samples are collected at random locations over the world and are analyzed in regional laboratories for their krypton-85 concentration. Further, it is argued that krypton-85 emissions from declared reprocessing activities have to be significantly lowered to enable a worldwide verification of the absence of even smaller clandestine reprocessing. For each scenario the number of samples that have to be taken for probable detection is calculated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Krypton 81m and xenon 133 for complementary ventilation imaging in pulmonary perfusion studies: a clinical comparison. Chapter 12

    International Nuclear Information System (INIS)

    Weber, P.M.; Remedios, L.V.dos.

    1978-01-01

    Twenty-four patients with suspected pulmonary embolism were studied to determine the relative usefulness of 133 Xe and 81 Krsup(m) as indicators of pulmonary ventilation in complementing perfusion studies. In most cases, where krypton produced results superior to xenon, this could be attributed to better resolution of the 190 keV photon and to the fact that multiple views could be obtained, with each view paired precisely with a corresponding perfusion image, the direct result of the ease of use of krypton and its short 13 second half-life. This was well demonstrated in both of the patients with presumed pulmonary embolism and co-existing other pulmonary disease in which the results with xenon and krypton differed. In each case the mis-match was obscured by closely related areas of delayed xenon wash-out. In those patients where xenon demonstrated greater sensitivity in identifying areas of pulmonary disease, the lesions noted on wash-out appeared as areas of positive activity, while with krypton the defects were always photogenic and, when small probably obscured by scatter from adjacent normal activity. In the patient who might have been improperly categorized as a mis-match without the krypton study, the xenon study may have been normal because of inadequate equilibration time. (author)

  14. A survey of methods for separating and immobilizing krypton-85 arising from a nuclear fuel reprocessing plant

    International Nuclear Information System (INIS)

    Taylor, P.

    1990-12-01

    This report reviews the literature on methods to separate and immobilize krypton-85 arising from dissolution or prior treatment of nuclear fuel in a reprocessing plant. It was prepared as part of a broader review of fuel reprocessing waste management methods that might find future applications in Canada. Cryogenic distillation is the most fully demonstrated method of separation of krypton from off-gases, but it is complex. In particular, it requires pretreatment of the gas stream to eliminate several other components before the final distillation. The most highly developed alternative process is fluorocarbon adsorption, while several other processes have been investigated on a bench scale. The simplest method of storing radioactive krypton is in compressed-gas cylinders, but the risks of accidental release are increased by the corrosive nature of the decay product, rubidium. Encapsulation in either a metal matrix or a hydrothermally vitrified zeolite appears to offer the most secure immobilization of krypton. Processes for both types of material have been demonstrated inactively on a scale approaching that required for treatment of off-gases from a commercial-scale fuel reprocessing plant. Low-operating temperatures and pressures of the metal encapsulation process, compared with encapsulation in zeolites, represent a definite advantage, but electrical power requirements for the former process are relatively high. It appears that suitable technology is available for separation and immobilization of radioactive krypton, should the need arise in Canada in the future

  15. Methane emissions from natural wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J.L. [Georgia Univ., Athens, GA (United States); Burke, R.A. Jr. [Environmental Protection Agency, Athens, GA (United States). Environmental Research Lab.

    1993-09-01

    Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

  16. [Agroindustrial wastes methanization and bacterial composition in anaerobic digestion].

    Science.gov (United States)

    González-Sánchez, María E; Pérez-Fabiel, Sergio; Wong-Villarreal, Arnoldo; Bello-Mendoza, Ricardo; Yañez-Ocampo, Gustavo

    2015-01-01

    The tons of organic waste that are annually generated by agro-industry, can be used as raw material for methane production. For this reason, it is important to previously perform biodegradability tests to organic wastes for their full scale methanization. This paper addresses biodegradability, methane production and the behavior of populations of eubacteria and archaeabacteria during anaerobic digestion of banana, mango and papaya agroindustrial wastes. Mango and banana wastes had higher organic matter content than papaya in terms of their volatile solids and total solid rate (94 and 75% respectively). After 63 days of treatment, the highest methane production was observed in banana waste anaerobic digestion: 63.89ml CH4/per gram of chemical oxygen demand of the waste. In the PCR-DGGE molecular analysis, different genomic footprints with oligonucleotides for eubacteria and archeobacteria were found. Biochemical methane potential results proved that banana wastes have the best potential to be used as raw material for methane production. The result of a PCR- DGGE analysis using specific oligonucleotides enabled to identify the behavior of populations of eubacteria and archaeabacteria present during the anaerobic digestion of agroindustrial wastes throughout the process. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Effect of hemicellulolytic enzymes on mesophilic methane fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Oi, S; Matsui, Y; Iizuka, M; Yamamoto, T

    1977-01-01

    Mesophilic methane fermentation was examined using soybean seed coat, a waste from soybean processing for oil manufacture, with or without treatment with hemicellulolytic enzymes of Aspergillus niger, and the following results were obtained: (1) The methane fermentation bacteria acclimated to soybean seed coat medium were shown to consume monosaccharides and evolve methane in the following decreasing order: glucose, fructose, mannose > xylose, galactose, glucosamine, galacturonic acid > arabinose. The bacteria were also shown to form methane from a gas mixture of hydrogen and carbon dioxide. (2) In fermentation of soybean seed coat treated with the fungal enzyme, about 70% of the total sugar content as consumed in four weeks, and the gas evolution was about twice that without the fungal enzyme. The gas evolved was composed of 60% methane and 36% carbon dioxide. In general, vigorous evolution of hydrogen and carbon dioxide occurred at a very early stage of fermentation, and was followed by formation of methane. The maximum gas evolution of the enzyme-treated mash took place in 6 days while that of untreated mash occurred one week later. Chemical oxygen demand of the supernatant of the former mash was decreased by fermentation to 7.0% of the initial level.

  18. Generation of Multicharged Krypton Ions in Nanosecond Laser Ionization of Krypton Beam%纳秒激光电离产生Kr17+的研究

    Institute of Scientific and Technical Information of China (English)

    罗晓琳; 孔祥蕾; 牛冬梅; 渠洪波; 李海洋

    2004-01-01

    Up to Kr17+ muhicharged krypton ions have been observed in time-of-flight mass spectrum by a 25 ns Nd-YAG 1. 064 μm laser at laser intensity about 1012 W/cm2. Experimental results indicate that the muhicharged ions appear only when the laser interacts with the middle part of the pulsed beam, and the intensities of the multi charged ions increase dramatically by increasing the backing pressure of Kr gas, which indicates that the clusters in the beam is essential to the production of muhicharged ions. From the experimental results, it is concluded that the cluster is ionized via multiphoton ionization and forms a nanoplasma ball, which can absorb the laser resonantly to further ionize the single charge ion to the high charge state.

  19. Design and construction of a cryogenic distillation device for removal of krypton for liquid xenon dark matter detectors.

    Science.gov (United States)

    Wang, Zhou; Bao, Lei; Hao, Xihuan; Ju, Yonglin

    2014-01-01

    Liquid xenon (Xe) is one of the commendable detecting media for the dark matter detections. However, the small content of radioactive krypton-85 ((85)Kr) always exists in the commercial xenon products. An efficient cryogenic distillation system to remove this krypton (Kr) from commercial xenon products has been specifically designed, developed, and constructed in order to meet the requirements of the dark matter experiments with high- sensitivity and low-background. The content of krypton in regular commercial xenon products can be reduced from 10(-9) to 10(-12), with 99% xenon collection efficiency at maximum flow rate of 5 kg/h (15SLPM). The purified xenon gases produced by this distillation system can be used as the detecting media in the project of Panda X, which is the first dark matter detector developed in China.

  20. Trends for Methane Oxidation at Solid Oxide Fuel Cell Conditions

    DEFF Research Database (Denmark)

    Kleis, Jesper; Jones, Glenn; Abild-Pedersen, Frank

    2009-01-01

    First-principles calculations are used to predict a plausible reaction pathway for the methane oxidation reaction. In turn, this pathway is used to obtain trends in methane oxidation activity at solid oxide fuel cell (SOFC) anode materials. Reaction energetics and barriers for the elementary...... the Ni surfaces to other metals of interest. This allows the reactivity over the different metals to be understood in terms of two reactivity descriptors, namely, the carbon and oxygen adsorption energies. By combining a simple free-energy analysis with microkinetic modeling, activity landscapes of anode...

  1. Production of Methane and Water from Crew Plastic Waste

    Science.gov (United States)

    Captain, Janine; Santiago, Eddie; Parrish, Clyde; Strayer, Richard F.; Garland, Jay L.

    2008-01-01

    Recycling is a technology that will be key to creating a self sustaining lunar outpost. The plastics used for food packaging provide a source of material that could be recycled to produce water and methane. The recycling of these plastics will require some additional resources that will affect the initial estimate of starting materials that will have to be transported from earth, mainly oxygen, energy and mass. These requirements will vary depending on the recycling conditions. The degredation products of these plastics will vary under different atmospheric conditions. An estimate of the the production rate of methane and water using typical ISRU processes along with the plastic recycling will be presented.

  2. Feasibility of Single Scan for Simultaneous Evaluation of Regional Krypton and Iodine Concentrations with Dual-Energy CT: An Experimental Study.

    Science.gov (United States)

    Hong, Sae Rom; Chang, Suyon; Im, Dong Jin; Suh, Young Joo; Hong, Yoo Jin; Hur, Jin; Kim, Young Jin; Choi, Byoung Wook; Lee, Hye-Jeong

    2016-11-01

    Purpose To evaluate the feasibility of a simultaneous single scan of regional krypton and iodine concentrations by using dual-energy computed tomography (CT). Materials and Methods The study was approved by the institutional animal experimental committee. An airway obstruction model was first made in 10 beagle dogs, and a pulmonary arterial occlusion was induced in each animal after 1 week. For each model, three sessions of dual-energy CT (80% krypton ventilation [krypton CT], 80% krypton ventilation with iodine enhancement [mixed-contrast agent CT], and iodine enhancement [iodine CT]) were performed. Krypton maps were made from krypton and mixed-contrast agent CT, and iodine maps were made from iodine and mixed-contrast agent CT. Observers measured overlay Hounsfield units of the diseased and contralateral segments on each map. Values were compared by using the Wilcoxon signed-rank test. Results In krypton maps of airway obstruction, overlay Hounsfield units of diseased segments were significantly decreased compared with those of contralateral segments in both krypton and mixed-contrast agent CT (P = .005 for both). However, the values of mixed-contrast agent CT were significantly higher than those of krypton CT for both segments (P = .005 and .007, respectively). In iodine maps of pulmonary arterial occlusion, values were significantly lower in diseased segments than in contralateral segments for both iodine and mixed-contrast agent CT (P = .005 for both), without significant difference between iodine and mixed-contrast agent CT for both segments (P = .126 and .307, respectively). Conclusion Although some limitations may exist, it might be feasible to analyze regional krypton and iodine concentrations simultaneously by using dual-energy CT. © RSNA, 2016.

  3. Krypton K-shell X-ray spectra recorded by the HENEX spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Seely, J.F. [Naval Research Laboratory, Space Science Division, Washington DC 20375 (United States)]. E-mail: john.seely@nrl.navy.mil; Back, C.A. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Constantin, C. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Lee, R.W. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Chung, H.-K. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Hudson, L.T. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Szabo, C.I. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Henins, A. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Holland, G.E. [SFA Inc., 9315 Largo Drive West Suite 200, Largo MD 20774 (United States); Atkin, R. [Tiger Innovations, L.L.C., 3610 Vacation Lane, Arlington VA 22207 (United States); Marlin, L. [Naval Research Laboratory, Space Science Division, Washington DC 20375 (United States)

    2006-05-15

    High-resolution X-ray spectra were recorded by the High-Energy Electronic X-ray (HENEX) spectrometer from a variety of targets irradiated by the Omega laser at the Laboratory for Laser Energetics. The HENEX spectrometer utilizes four reflection crystals covering the 1-20keV energy range and one quartz(10-11) transmission crystal (Laue geometry) covering the 11-40keV range. The time-integrated spectral images were recorded on five CMOS X-ray detectors. In the spectra recorded from krypton-filled gasbag and hohlraum targets, the helium-like K-shell transitions n=1-2, 1-3, and 1-4 appeared in the 13-17keV energy range. A number of additional spectral features were observed at energies lower than the helium-like n=1-3 and n=1-4 transitions. Based on computational simulations of the spectra using the FLYCHK/FLYSPEC codes, which included opacity effects, these additional features are identified to be inner-shell transitions from the Li-like through N-like krypton charge states. The comparisons of the calculated and observed spectra indicate that these transitions are characteristic of the plasma conditions immediately after the laser pulse when the krypton density is 2x10{sup 18}cm{sup -3} and the electron temperature is in the range 2.8-3.2keV. These spectral features represent a new diagnostic for the charge state distribution, the density and electron temperature, and the plasma opacity. Laboratory experiments indicate that it is feasible to record K-shell spectra from gold and higher Z targets in the >60keV energy range using a Ge(220) transmission crystal.

  4. A review of the separation and immobilisation of krypton arising from nuclear fuel reprocessing plant

    International Nuclear Information System (INIS)

    Judd, S.J.

    1992-01-01

    The techniques for the separation and immobilisation of 85 Kr are reviewed. Particular attention is paid to processes currently available or undergoing development on the technical to industrial scale. Of the separation processes, cryogenic distillation has reached the most advanced stage of development, with a pilot facility already undergoing radioactive demonstration. The PNC Kr-recovery pilot plant, which has a off-gas flow capacity of 110 m 3 hr -1 (approximately 1/4 the scale of THORP), is currently undergoing tests at Tokai Mura. Low-temperature absorption and adsorption processes have also reached the pilot plant stage but have yet to undergo radiological tests. The separated krypton has been conventionally stored as the compressed gas in cylinders, but progress made in encapsulation techniques suggest that more secure immobilisation can be achieved by encapsulation within a metal or zeolite matrix. Processes based on the implantation of krypton in a metal or metal alloy have been demonstrated on the technical scale with the radioactive gas. It is concluded that the technology for the separation, isolation and immobilisation of radioactive krypton is available only on a reduced scale compared with THORP. The investment cost of a 85 Kr management facility for THORP, based on cryogenic distillation followed by immobilisation by implantation in metal and assuming a 20 year plant life, is estimated at 51-57M pounds. The cost of prepurification of the off-gas stream is included in this figure. Accompanying operating costs, including those incurred by disposal of the encapsulate in geological formations, are estimated at 2.2-3.3 M pounds per annum. Further development work under radioactive conditions is still required prior to the application of existing technology to full-scale fuel reprocessing plant. (author)

  5. Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.

    Science.gov (United States)

    Wang, David T; Gruen, Danielle S; Lollar, Barbara Sherwood; Hinrichs, Kai-Uwe; Stewart, Lucy C; Holden, James F; Hristov, Alexander N; Pohlman, John W; Morrill, Penny L; Könneke, Martin; Delwiche, Kyle B; Reeves, Eoghan P; Sutcliffe, Chelsea N; Ritter, Daniel J; Seewald, Jeffrey S; McIntosh, Jennifer C; Hemond, Harold F; Kubo, Michael D; Cardace, Dawn; Hoehler, Tori M; Ono, Shuhei

    2015-04-24

    Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect of biological processes on methane's clumped isotopologue signature is poorly constrained. We show that methanogenesis proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic control on (13)CH3D abundances and results in anomalously elevated formation-temperature estimates. We demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry can therefore provide constraints on the generation of methane in diverse settings, including continental serpentinization sites and ancient, deep groundwaters. Copyright © 2015, American Association for the Advancement of Science.

  6. Process and apparatus for separating and recovering krypton-85 from exhaust gas of nuclear reactor or the like

    International Nuclear Information System (INIS)

    Yusa, H.; Kamiya, K.; Murata, T.; Yamaki, H.; Hisatomi, S.

    1975-01-01

    An apparatus is described for separating and recovering radioactive krypton-85 contained in an exhaust gas of a nuclear reactor or the like, which comprises a plurality of adsorption beds connected in parallel with respect to a passageway for the exhaust gas, each being packed with activated carbon, wherein adsorption and desorption of krypton-85 in each of the beds are alternatively and repeatedly performed by operating valves disposed between each of the beds and means for reducing pressure in the beds to be desorbed in accordance with a predetermined time schedule. The adsorption and concentration efficiencies are markedly increased by combining the above adsorption apparatus and a distillation apparatus

  7. Methane from dairy waste

    Energy Technology Data Exchange (ETDEWEB)

    1982-10-22

    This short article describes a facility which will incorporate features to allow for the recovery of the methane gas that is produced in the manufacture of cheese and spray-dried whey powder at the site. The dairy plant is expected to produce about 1,385 m/sup 3//day of methane which will supplement the operation of oil burners and replace the annual consumption of 4,000 bbl of heavy fuel oil. In addition, development of the treatment system would eliminate the consumption of 7,200 kWh/day of electrical energy that would otherwise be required to operate an aerobic disposal system. Total annual energy savings, when the project is fully operational in the spring of 1984, are expected to reach $321,000.

  8. Methanation: reality or fiction?

    International Nuclear Information System (INIS)

    Gay, Michel

    2015-01-01

    The author discusses whether it is possible to partly replace oil and natural gas by electricity-based gas, i.e. to produce methane from water by electrolysis, or by using molecule cracking in dedicated nuclear reactors, and carbon dioxide. He outlines the benefits of this perspective in terms of reduction of imports, and of national electricity production optimisation. He also discusses the drawbacks: it will be difficult to produce the huge required quantity of CO 2 ; it will be even more difficult to produce the required quantity of electricity; the e-methane production cost is much higher than that of the currently imported natural gas. In appendix, the author discusses some key figures related to energy in France (consumption, shares, imports, crucial role of nuclear energy for the future)

  9. Pulmonary dynamics and functional imaging with krypton-81m as related to generator delivery characteristics

    International Nuclear Information System (INIS)

    Kaplan, E.

    1985-01-01

    Krypton-81m supplied from a generator by continuous elution with air is used with a gamma-camera computer system to produce a sequence of images from multiple breaths, which reconstructed the time-activity images of the breathing human lung. Functional images are produced by subsequent derivation to show specific variables of the dynamic sequences. The dynamic, quantitative, and regional aspects of the respiratory cycle are thus made available in a single study. The need for the delivery of a constant ratio of /sub 81m/Kr to air is required to accurately produce these various studies

  10. Thermodynamic consistency of vapor pressure and calorimetric data for argon, krypton, and xenon

    International Nuclear Information System (INIS)

    Schwalbe, L.A.; Crawford, R.K.; Chen, H.H.; Aziz, R.A.

    1977-01-01

    A new two-parameter vapor pressure equation has been derived which, unlike the Salter equation, is shown to be equally applicable to quantum or classical solids and even liquids. The condensed phase enthalpies and entropies are given directly by the fitted parameters with accuracies comparable to those which have been claimed for existing independent calorimetric measurements. Recent vapor pressure data for the solid and liquid phases of argon, krypton, and xenon are analyzed in this manner, and the results are compared with the available calorimetric data. New values for the cohesive energy at T=0 are also derived for these substances

  11. Study of production by cosmic radiation of krypton and xenon in the Saint-Severin meteorite

    International Nuclear Information System (INIS)

    Lavielle, B.

    1987-01-01

    The concentrations of Kr and Xe isotropes have been measured by a high sensitivity mass spectrometry technique in 11 samples from a core of the Saint-Severin meteorite. On the basis of our results, we were able to show the role of the shielding depth on the production of Kr and Xe by cosmic ray bombardment. More-over, the experimental results for krypton were compared with calculated values obtained by the Reedy and Arnold model (1972) adapted to cosmic ray irradiation of small spherical objects. Our elaboration of a new systematics of nuclear reactions has lead to a good agreement between experiments and calculations within this model [fr

  12. Comparison of iodine, krypton, and xenon retention efficiencies for various silver loaded adsorption media

    International Nuclear Information System (INIS)

    Huchton, R.L.; Tkachyk, J.W.; Taylor, J.T.; Motes, B.G.

    1985-03-01

    A comparison was made among various silver impregnated adsorption media to determine their iodine, krypton, and xenon retention efficiencies. The program consisted of three components. First, laboratory measurements of the noble gas retention efficiencies of commercially available adsorption media were determined as a function of relative humidity, sample duration, test cartridge geometry, and ambient air purge. Second, a literature survey was performed to evaluate the iodine species retention efficiencies of the selected media. Third, data associated with a media previously proposed for an emergency response air sampler were incorporated to enlarge the data base. 41 refs., 6 figs., 14 tabs

  13. Vacuum ultraviolet emission from argon, krypton, and xenon in a radial-viewed theta pinch

    International Nuclear Information System (INIS)

    Engleman, R. Jr.; Thomson, D.B.; Monaghan, D.A.

    1976-03-01

    Vacuum ultraviolet line emission from argon, krypton, and xenon (5 percent in deuterium) has been observed from a plasma (approximately 50 eV and N/sub e/ approximately 10 17 /cm 3 ) produced by the Scyllar linear theta-pinch device. More than 50 emission lines in the 30- to 500-A region have been measured for each gas mixture. Some lines have been identified as due to Ar VII through XI, Kr IX and X, and Xe IX, but many lines remain unassigned

  14. Angular distribution of Auger electrons due to 3d-shell ionization of krypton

    Science.gov (United States)

    Omidvar, K.

    1977-01-01

    Cross sections for electron impact ionization of krypton due to ejection of a 3rd shell electron have been calculated using screened hydrogenic and Hartree-Slater wave functions for target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3rd electrons, is widely different in the two approximations. The angular distribution due to Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

  15. Angular distribution of Auger electrons due to 3d-shell impact ionization of krypton

    Science.gov (United States)

    Omidvar, K.

    1977-01-01

    Cross sections for electron impact ionization of krypton due to ejection of a 3d-shell electron have been calculated using screened hydrogenic and Hartree-Slater wavefunctions for the target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3d electrons, are widely different in the two approximations. The angular distribution due to the Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

  16. Kratom alkaloids and O-desmethyltramadol in urine of a "Krypton" herbal mixture consumer.

    Science.gov (United States)

    Arndt, Torsten; Claussen, Ulrich; Güssregen, Brunhilde; Schröfel, Stefanie; Stürzer, Birgit; Werle, Annika; Wolf, Gerald

    2011-05-20

    A drug and alcohol withdrawal rehabilitation centre requested an analysis for "Krypton" in urine of a former opiate-addictive woman. She showed an altered clinical picture and behaviour with miosis, itchiness, agitation, and moderate euphoria after 3 months of until than successful treatment. Literature search revealed that "Krypton" is said to contain "Kratom" (leaves of Mitragyna speciosa), but could also contain O-desmethyltramadol (European Monitoring Centre for Drugs and Drug Addiction thematic paper "Spice"). Immunological drug screenings were done with test strips (nal von minden, Regensburg, Germany) and with cloned enzyme donor immunoassay (Microgenics, Passau, Germany). "Kratom" alkaloids and tramadol (metabolites) were analyzed by LC-MS/MS (ThermoFisher Scientific Quantum Ultra Triple Quadrupole mass spectrometer). Immunoassays were negative for amphetamines, barbiturates, benzodiazepines, benzoylecgonine, buprenorphine, ethylglucuronide, methadone (metabolite), opiates, oxycodone, and THC-COOH, and test strips were negative for tramadol and its metabolites (cut-off 10 mg/L for O-desmethyltramadol). LC-MS/MS detected the "Kratom" alkaloids mitragynine, speciociliatine, speciogynine, mitraciliatine, and paynantheine and approximately 9mg/L O-desmethyltramadol, but no tramadol and N-desmethyltramadol. The detection of M. speciosa alkaloids is a proof of "Kratom" abuse. Confronted with the analysis data, the patient admitted to have consumed 3-4 infusions of "Krypton". The origin of the O-desmethyltramadol is unclear. Tramadol abuse is unlikely since tramadol and N-desmethyltramadol (physiologically occurring in urine after tramadol intake) were not detectable. Consumption of a "Krypton" product spiked with O-desmethyltramadol could explain our findings and the patient's clinical picture. This would be in agreement with a most recent report about spiking apparently natural herbal mixtures with the synthetic opioid O-desmethyltramadol. Analysis of "Kratom

  17. Krypton laser photocoagulation induces retinal vascular remodeling rather than choroidal neovascularization.

    Science.gov (United States)

    Behar-Cohen, F; Benezra, D; Soubrane, G; Jonet, L; Jeanny, J C

    2006-08-01

    The purpose of this study is to analyze the retina and choroid response following krypton laser photocoagulation. Ninety-two C57BL6/Sev129 and 32 C57BL/6J, 5-6-week-old mice received one single krypton (630 nm) laser lesion: 50 microm, 0.05 s, 400 mW. On the following day, every day thereafter for 1 week and every 2-3 days for the following 3 weeks, serial sections throughout the lesion were systematically collected and studied. Immunohistology using specific markers or antibodies for glial fibrillary acidic protein (GFAP) (astrocytes, glia and Muller's cells), von Willebrand (vW) (vascular endothelial cells), TUNEL (cells undergoing caspase dependent apoptosis), PCNA (proliferating cell nuclear antigen) p36, CD4 and F4/80 (infiltrating inflammatory and T cells), DAPI (cell nuclei) and routine histology were carried out. Laser confocal microscopy was also performed on flat mounts. Temporal and spatial observations of the created photocoagulation lesions demonstrate that, after a few hours, activated glial cells within the retinal path of the laser beam express GFAP. After 48 h, GFAP-positive staining was also detected within the choroid lesion center. "Movement" of this GFAP-positive expression towards the lasered choroid was preceded by a well-demarcated and localized apoptosis of the retina outer nuclear layer cells within the laser beam path. Later, death of retinal outer nuclear cells and layer thinning at this site was followed by evagination of the inner nuclear retinal layer. Funneling of the entire inner nuclear and the thinned outer nuclear layers into the choroid lesion center was accompanied by "dragging" of the retinal capillaries. Thus, from days 10 to 14 after krypton laser photocoagulation onward, well-formed blood capillaries (of retinal origin) were observed within the lesion. Only a few of the vW-positive capillary endothelial cells stained also for PCNA p36. In the choroid, dilatation of the vascular bed occurred at the vicinity of the

  18. Generation of spectrally stable 6.5-fs visible pulses via filamentation in krypton

    Institute of Scientific and Technical Information of China (English)

    Keisuke Kaneshima; Kengo Takeuchi; Nobuhisa Ishii; Jiro Itatani

    2016-01-01

    We produced 5-μJ, 6.5-fs visible pulses at a repetition rate of 1 kHz using filamentation in a gas cell filled with krypton followed by spectral selection and phase compensation by a combination of dielectric mirrors. The visible pulses have a smooth spectrum from 520 to 650 nm with a shot-to-shot stability in each spectral component of better than 2%(standard deviation). This pulse compression scheme is simple and robust, and can be easily integrated into intense ultrashort-pulse laser systems.

  19. Comparison of Medium Power Hall Effect Thruster Ion Acceleration for Krypton and Xenon Propellants

    Science.gov (United States)

    2016-09-14

    Pumping is provided by four single-stage cryogenic panels (single-stage cold heads at 25 K) and one 50 cm two stage cryogenic pump (12 K). This vacuum...test chamber has a mea- sured pumping speed of 36 kL/s on xenon. The Hall thruster used in this study is a medium power laboratory Hall effect...The first compo- nent passes through a krypton opto-galvanic cell and is terminated by a beam dump . The opto-galvanic cell current is capacitively

  20. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    Energy Technology Data Exchange (ETDEWEB)

    Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

    2014-01-29

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

  1. The sputtering of the deformed gold under irradiation with krypton swift heavy ions

    International Nuclear Information System (INIS)

    Didyk, A.Yu.; Semina, V.K.; Hofman, A.

    2002-01-01

    The results about sputtering yield of gold irradiated by 86 Kr ions with high inelastic energy losses up to a fluence of 10 14 ion/cm 2 are presented. It was shown that the sputtering (evaporation) yield strongly depends on the initial defect concentration in gold. The sputtering yield begins to grow very strongly with the increasing of damage created by heavy ion elastic and inelastic energy losses. The temperature on the surface in the area around krypton ion trajectory is much higher than the melting and evaporation temperatures for gold as follows from calculations with the various expressions and models

  2. Method of determining paper-deposited materials, eg. lead, by their reaction with radioactive krypton

    International Nuclear Information System (INIS)

    Tolgyessy, J.; Pruzinec, J.

    1976-01-01

    The invention claims a method of determining substances on a paper carrier based on the substance reaction with 85 Kr gas and the measurement of radioactivity of the kryptonate formed. Lead is shown as an example. Different amounts of lead acetate were deposited on Whatman 2 chromatographic paper as was an unknown sample of Pb salt. The paper was exposed to a 2.5 mCi 85 Kr atmosphere for 48 hours. The activity of the individual spots was then measured, a calibration curve established and the amount of lead in the analyzed sample read-out. (Ha)

  3. Project identification for methane reduction options

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, T.

    1996-12-31

    This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of the projects, and additional gains which come from the projects.

  4. Lithium chemistry of lithium doped magnesium oxide catalysts used in the oxidative coupling of methane

    NARCIS (Netherlands)

    Korf, S.J.; Roos, J.A.; de Bruijn, N.A.; van Ommen, J.G.; Ross, J.R.H.

    1990-01-01

    Active sites are created on the surface of a Li/MgO catalyst used for the selective oxidation of methane by the gradual loss of carbon dioxide from surface carbonate species in the presence of oxygen. Decomposition of the carbonate species in the absence of oxygen is detrimental to the activity of

  5. Photofragment imaging of methane

    International Nuclear Information System (INIS)

    Heck, A.J.; Zare, R.N.; Chandler, D.W.

    1996-01-01

    The photolysis of methane is studied using photofragment imaging techniques. Our study reveals that the photolysis of methane proceeds via many different pathways. The photofragment imaging technique is used to resolve and characterize these various pathways and provides therefore unique insight into the dynamical processes that govern this photodissociation. The formation of H-atom photofragments following absorption of a Lyman-α photon, and H 2 photofragments following absorption of two ultraviolet photons (λ=210 endash 230 nm) are studied. The measured H-atom photofragment images reveal that a channel that produces fast H atoms concomitant with methyl fragments is dominant in the Lyman-α photolysis of methane. This channel leads to an anisotropic recoil of the fragments. A secondary channel is observed leading to the formation of somewhat slower H atoms, but an unique identification of this second channel is not possible from the data. At least part of these slower H atoms are formed via a channel that produces H atoms concomitant with CH and H 2 photofragments. The recoil of these slower H atoms appears to be isotropic. The measured, state-resolved H 2 (v,J), photofragment images reveal that two channels lead to H 2 photofragments from the two-photon photolysis of methane: a channel that leads to H 2 products concomitant with methylene fragments; and a channel that leads to H 2 products concomitant with CH and H fragments. H 2 (v,J) rotational and vibrational distributions are measured for each of these two channels separately. The H 2 products formed via the H 2 +CH 2 channel are rotationally and vibrationally highly excited, whereas those formed via the H 2 +CH+H channel are rotationally and vibrationally cooler. Rotational distributions of H 2 formed via the H 2 +CH+H channel are well reproduced by Boltzmann distributions. (Abstract Truncated)

  6. Coal Bed Methane Primer

    Energy Technology Data Exchange (ETDEWEB)

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  7. Genomic selection for methane emission

    DEFF Research Database (Denmark)

    de Haas, Yvette; Pryce, Jennie E; Wall, Eileen

    2016-01-01

    Climate change is a growing area of international concern, and it is well established that the release of greenhouse gases (GHG) is a contributing factor. Of the various GHG produced by ruminants, enteric methane (CH4 ) is the most important contributor. One mitigation strategy is to reduce methane...... emission through genetic selection. Our first attempt used beef cattle and a GWAS to identify genes associated with several CH4 traits in Angus beef cattle. The Angus population consisted of 1020 animals with phenotypes on methane production (MeP), dry matter intake (DMI), and weight (WT). Additionally......, two new methane traits: residual genetic methane (RGM) and residual phenotypic methane (RPM) were calculated by adjusting CH4 for DMI and WT. Animals were genotyped using the 800k Illumina Bovine HD Array. Estimated heritabilities were 0.30, 0.19 and 0.15 for MeP, RGM and RPM respectively...

  8. In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests

    International Nuclear Information System (INIS)

    Smith, R.L.; Howes, B.L.; Garabedian, S.P.

    1991-01-01

    Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluoroethane) tracers and was confirmed by the appearance of 13 C-enriched carbon dioxide in experiments in which 13 C-enriched methane was used as the tracer. A V max for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional advection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The K m values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 μM for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems

  9. Methanization of industrial liquid effluents

    International Nuclear Information System (INIS)

    Frederic, S.; Lugardon, A.

    2007-01-01

    In a first part, this work deals with the theoretical aspects of the methanization of the industrial effluents; the associated reactional processes are detailed. The second part presents the technological criteria for choosing the methanization process in terms of the characteristics of the effluent to be treated. Some of the methanization processes are presented with their respective advantages and disadvantages. At last, is described the implementation of an industrial methanization unit. The size and the main choices are detailed: the anaerobic reactor, the control, the valorization aspects of the biogas produced. Some examples of industrial developments illustrate the different used options. (O.M.)

  10. Methane emissions from coal mining

    International Nuclear Information System (INIS)

    Boyer, C.M.; Kelafant, J.R.; Kuuskraa, V.A.; Manger, K.C.; Kruger, D.

    1990-09-01

    The report estimates global methane emissions from coal mining on a country specific basis, evaluates the technologies available to degasify coal seams and assesses the economics of recovering methane liberated during mining. 33 to 64 million tonnes were liberated in 1987 from coal mining, 75 per cent of which came from China, the USSR, Poland and the USA. Methane emissions from coal mining are likely to increase. Emission levels vary between surface and underground mines. The methane currently removed from underground mines for safety reasons could be used in a number of ways, which may be economically attractive. 55 refs., 19 figs., 24 tabs

  11. Oxygen toxicity

    Directory of Open Access Journals (Sweden)

    C. A. van der Westhuizen

    1990-07-01

    Full Text Available Oxygen has been discovered about 200 years ago. Since then the vital physiological involvement of oxygen in various biologi­cal processes, mainly energy production, has been established. However, in the body molecular oxygen can be converted to toxic oxygen metabolites such as superoxide anion, hydrogen peroxide, the hydroxyl radical and singlet oxygen. These toxic metabolites are produced mainly in the mitochondria, plasma membranes and endoplasmic reticulum.

  12. Laser-optogalvanic studies of the 4p5 ns and nd autoionizing resonances in krypton

    International Nuclear Information System (INIS)

    Baig, M A; Hanif, M; Aslam, M

    2008-01-01

    We report new measurements of the odd-parity autoionizing resonances in krypton using resonant two-photon excitation from the 4p 5 5s[3/2] 2 metastable level in a mild DC discharge and an optogalvanic detection technique. We have observed the 4p 5 ns [1/2] 0,1 , 4p 5 nd [3/2] 2 and 4p 5 nd [5/2] 2,3 autoionizing resonances excited from three intermediate levels 4p 5 5p' [1/2] 1 , 4p 5 5p' [3/2] 1 and 4p 5 5p' [3/2] 2 . The spectra are notable for the absence of the broad autoionizing 4p 5 nd [3/2] 1 series which dominates in the photo-absorption spectrum from the ground state. The prominent transitions follow ΔK = ΔJ = Δl selection rules of the JK-coupling scheme. We report nearly 100 new energy levels in krypton besides the quantum defects and the reduced widths Γ r Γ(ν) 3 of the nd' [3/2] 2 , nd' [5/2] 2 and nd' [5/2] 3 Rydberg states

  13. All-optical atom trap trace analysis for rare krypton isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Woelk, Pablo; Kohler, Markus; Sieveke, Carsten; Hebel, Simon; Sahling, Peter [Carl Friedrich von Weizsaecker Centre for Science and Peace Research, University of Hamburg (Germany); Becker, Christoph; Sengstock, Klaus [Institut fuer Laser-Physik, University of Hamburg (Germany)

    2016-07-01

    The isotope Krypton-85 is an excellent indicator for the detection of nuclear reprocessing activities. However, for the analysis of atmospheric air samples, sensitive measuring methods down to the single atom level are required because of the small concentrations. Furthermore, for a practical and effective detection of clandestine reprocessing, small sample sizes and a high sample throughput rate are desirable. Established methods using Atom Trap Trace Analysis (ATTA) allow high sensitivity but have a limited throughput of about 200 samples per year, since the vacuum chambers have to be flushed for several hours after each measurement to avoid cross contamination due to the RF-driven excitation of metastable states. Here we present an enhanced ATTA apparatus, which in contrast to the established methods, produces metastable Kr all-optically. This avoids cross contamination, therefore allowing a much higher throughput rate. The apparatus is based on a self-made VUV-lamp and a 2D-3D magneto-optical trap setup. In the 2D trap metastable krypton is produced and a beam of atoms is formed by Doppler-cooling simultaneously.

  14. Four-body interaction energy for compressed solid krypton from quantum theory.

    Science.gov (United States)

    Tian, Chunling; Wu, Na; Liu, Fusheng; Saxena, Surendra K; Zheng, Xingrong

    2012-07-28

    The importance of the four-body contribution in compressed solid krypton was first evaluated using the many-body expansion method and the coupled cluster theory with full single and double excitations plus perturbative treatment of triples. All different four-atom clusters existing in the first- and second-nearest neighbor shells of face-centered cubic krypton were considered, and both self-consistent-field Hartree-Fock and correlation parts of the four-body interaction were accurately determined from the ambient conditions up to eightfold volume compression. We find that the four-body interaction energy is negative at compression ratio lower than 2, where the dispersive forces play a dominant role. With increasing the compression, the four-body contribution becomes repulsive and significantly cancels the over-softening effects of the three-body potential. The obtained equation of state (EOS) was compared with the experiments and the density-functional theory calculations. It shows that combination of the four-body effects with two- and three-body interactions leads to an excellent agreement with EOS measurements throughout the whole experimental range 0-130 GPa, and extends the prediction to 300 GPa.

  15. L-shell spectroscopic diagnostics of radiation from krypton HED plasma sources

    Energy Technology Data Exchange (ETDEWEB)

    Petkov, E. E., E-mail: emilp@unr.edu; Safronova, A. S.; Kantsyrev, V. L.; Shlyaptseva, V. V. [University of Nevada, Reno, Nevada 89557 (United States); Rawat, R. S.; Tan, K. S. [National Institute of Education, Nanyang Technological University, Singapore 637616 (Singapore); Beiersdorfer, P.; Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, 96049 Bamberg (Germany)

    2016-11-15

    X-ray spectroscopy is a useful tool for diagnosing plasma sources due to its non-invasive nature. One such source is the dense plasma focus (DPF). Recent interest has developed to demonstrate its potential application as a soft x-ray source. We present the first spectroscopic studies of krypton high energy density plasmas produced on a 3 kJ DPF device in Singapore. In order to diagnose spectral features, and to obtain a more comprehensive understanding of plasma parameters, a new non-local thermodynamic equilibrium L-shell kinetic model for krypton was developed. It has the capability of incorporating hot electrons, with different electron distribution functions, in order to examine the effects that they have on emission spectra. To further substantiate the validity of this model, it is also benchmarked with data gathered from experiments on the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory, where data were collected using the high resolution EBIT calorimeter spectrometer.

  16. Energy-momentum structure of the krypton valence shell by electron-momentum spectroscopy

    International Nuclear Information System (INIS)

    Nicholson, R.; Braidwood, S.W.; McCathy, I.E.; Weigold, E.; Brunger, M.J.

    1996-03-01

    Momentum distributions and spectroscopic factors are obtained in a high resolution electron-momentum spectroscopy study of krypton at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in good agreement with the results of calculations made within the distorted-wave impulse approximation (DWIA) framework. The DWIA describes the relative magnitudes of the 4p and 4s manifolds as well as giving a good representation of the shapes of the respective 4p and 4s cross sections. Results for the momentum profiles belonging to excited 2 P o and 2 S e manifolds are also presented. Spectroscopic factors for transitions belonging to the 2 p o and 2 S e manifolds are assigned up to a binding energy of 42 eV. The spectroscopic factor for the lowest 4s transition is 0.51 ± 0.01, whereas that for the ground-state 4p transition is 0.98± 0.01. Comparisons of the present binding energies and spectroscopic factors are made against the results of several many-body calculations and photoelectron spectroscopy (PES) results. In addition, a new procedure is outlined, utilising the experimental 4p and 4s manifold cross sections, that provides information on possible initial state configuration interaction effects in krypton. 50 refs., 2 tabs., 10 figs

  17. Removing krypton from xenon by cryogenic distillation to the ppq level

    Energy Technology Data Exchange (ETDEWEB)

    Aprile, E.; Anthony, M.; De Perio, P.; Gao, F.; Goetzke, L.W.; Greene, Z.; Messina, M.; Plante, G.; Rizzo, A.; Zhang, Y. [Columbia University, Physics Department, New York, NY (United States); Aalbers, J.; Breur, P.A.; Brown, A.; Colijn, A.P.; Decowski, M.P.; Hogenbirk, E.; Tiseni, A. [Nikhef and the University of Amsterdam, Science Park, Amsterdam (Netherlands); Agostini, F. [INFN-Laboratori Nazionali del Gran Sasso (Italy); Gran Sasso Science Institute, L' Aquila (Italy); University of Bologna, Department of Physics and Astrophysics, Bologna (Italy); INFN-Bologna (Italy); Alfonsi, M.; Geis, C.; Grignon, C.; Oberlack, U.; Scheibelhut, M.; Schindler, S. [Johannes Gutenberg-Universitaet Mainz, Institut fuer Physik and Exzellenzcluster PRISMA, Mainz (Germany); Amaro, F.D.; Cardoso, J.M.R.; Lopes, J.A.M.; Orrigo, S.E.A.; Santos, J.M.F. dos; Silva, M. [University of Coimbra, Department of Physics, Coimbra (Portugal); Arneodo, F.; Benabderrahmane, M.L.; Di Giovanni, A.; Maris, I. [New York University Abu Dhabi, Abu Dhabi (United Arab Emirates); Barrow, P.; Baudis, L.; Franco, D.; Galloway, M.; Kessler, G.; Kish, A.; Mayani, D.; Pakarha, P.; Piastra, F.; Wei, Y.; Wulf, J. [Physik-Institut, University of Zurich, Zurich (Switzerland); Bauermeister, B. [Johannes Gutenberg-Universitaet Mainz, Institut fuer Physik and Exzellenzcluster PRISMA, Mainz (Germany); Stockholm University, AlbaNova, Oskar Klein Centre, Department of Physics, Stockholm (Sweden); Berger, T.; Brown, E.; Piro, M.C. [Rensselaer Polytechnic Institute, Department of Physics, Applied Physics and Astronomy, Troy, NY (United States); Bruenner, S.; Cichon, D.; Eurin, G.; Hasterok, C.; Lindemann, S.; Lindner, M.; Undagoitia, T.M.; Pizzella, V.; Rauch, L.; Rupp, N.; Schreiner, J.; Simgen, H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Bruno, G.; Gallo Rosso, A.; Molinario, A. [INFN-Laboratori Nazionali del Gran Sasso (Italy); Gran Sasso Science Institute, L' Aquila (Italy); Budnik, R.; Duchovni, E.; Itay, R.; Landsman, H.; Lellouch, D.; Levinson, L.; Manfredini, A.; Priel, N. [Weizmann Institute of Science, Department of Particle Physics and Astrophysics, Rehovot (Israel); Buetikofer, L.; Coderre, D.; Kaminsky, B.; Schumann, M.; Sivers, M. v. [Universitaet Freiburg, Physikalisches Institut, Freiburg (Germany); Calven, J.; Conrad, J.; Ferella, A.D.; Pelssers, B. [Stockholm University, AlbaNova, Oskar Klein Centre, Department of Physics, Stockholm (Sweden); Cervantes, M.; Lang, R.F.; Masson, D.; Pienaar, J.; Reichard, S.; Reuter, C. [Purdue University, Department of Physics and Astronomy, West Lafayette, IN (United States); Cussonneau, J.P.; Diglio, S.; Le Calloch, M.; Masbou, J.; Micheneau, K.; Persiani, R.; Thers, D. [Universite de Nantes, SUBATECH, Ecole des Mines de Nantes, CNRS/In2p3, Nantes (France); Di Gangi, P.; Garbini, M.; Massoli, F.V.; Sartorelli, G.; Selvi, M. [University of Bologna, Department of Physics and Astrophysics, Bologna (Italy); INFN-Bologna (Italy); Fei, J.; Ni, K.; Ye, J. [University of California, Department of Physics, San Diego, CA (United States); Fieguth, A.; Huhmann, C.; Murra, M.; Rosendahl, S.; Weinheimer, C. [Westfaelische Wilhelms-Universitaet Muenster, Institut fuer Kernphysik, Muenster (Germany); Fulgione, W. [INFN-Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, L' Aquila (Italy); INFN-Torino (Italy); Osservatorio Astrofisico di Torino, Torino (Italy); Grandi, L.; Saldanha, R.; Shockley, E.; Upole, N. [University of Chicago, Department of Physics and Kavli Institute of Cosmological Physics, Chicago, IL (United States); Lin, Q. [Laboratori Nazionali del Gran Sasso, Assergi (Italy); Meng, Y.; Stein, A.; Wang, H. [University of California, Physics and Astronomy Department, Los Angeles, CA (United States); Miguez, B.; Trinchero, G. [INFN-Torino (Italy); Osservatorio Astrofisico di Torino, Torino (Italy); Naganoma, J.; Shagin, P. [Rice University, Department of Physics and Astronomy, Houston, TX (United States); Lavina, L.S. [LPNHE, Universite Pierre et Marie Curie, Universite Paris Diderot, CNRS/IN2P3, Paris (France); Tunnell, C. [Nikhef and the University of Amsterdam, Science Park, Amsterdam (Netherlands); University of Chicago, Department of Physics and Kavli Institute of Cosmological Physics, Chicago, IL (United States); Cristescu, I. [Karlsruhe Institute of Technology, Tritium Laboratory Karlsruhe, Eggenstein-Leopoldshafen (Germany); Collaboration: XENON Collaboration

    2017-05-15

    The XENON1T experiment aims for the direct detection of dark matter in a detector filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. One major contributor is the β-emitter {sup 85}Kr which is present in the xenon. For XENON1T a concentration of natural krypton in xenon {sup nat}Kr/Xe < 200 ppq (parts per quadrillion, 1 ppq = 10{sup -15} mol/mol) is required. In this work, the design, construction and test of a novel cryogenic distillation column using the common McCabe-Thiele approach is described. The system demonstrated a krypton reduction factor of 6.4 . 10{sup 5} with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of {sup nat}Kr/Xe < 26 ppq is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN. (orig.)

  18. Electron excitation coefficients of neutral and ionic levels of krypton in Townsend discharges

    International Nuclear Information System (INIS)

    Malovic, G.N.; Strinic, A.I.; Petrovic, Z.Lj.; Sadeghi, N.

    2006-01-01

    In this paper, we present experimental results for excitation coefficients of krypton atoms to several Kr and Kr + excited levels for E/N (electric field to gas particle number density ratio usually in units of Townsend, 1 Td = 10 -21 V m 2 ) values from 7 x 10 -20 V m 2 to above 1 x 10 -17 V m 2 . The data have been obtained in two different parallel plate self-sustained Townsend discharge drift tubes. The spatial distribution of the emission intensities were recorded and then normalized to give excitation coefficients at the anode, by using the electron flux at this point. The values of these coefficients are placed on an absolute scale by using a standard tungsten ribbon lamp calibrated against a primary blackbody radiation standard. The ionization rates at different E/N are obtained from the spatial emission profiles. The data for atomic krypton levels 2p 2 , 2p 3 , 2p 5 , 2p 6 , 2p 7 , 2p 8 , 3p 5 and 3p 6 (in Paschen notation) were converted to excitation coefficients by using quenching coefficients from the literature. The emission coefficients of eight 4s 2 4p 4 ( 3 P)5p levels of Kr + have also been measured for E/N values from about 1 x 10 -18 V m 2 up to nearly 8 x 10 -18 V m 2

  19. Photon W value for krypton in the M-shell transition region.

    Science.gov (United States)

    Saito, N; Suzuki, I H

    2001-09-01

    Absolute W values for krypton have been measured for incident X rays with energies in the range of 85 to 1000 eV, using monochromatic synchrotron radiation and a multiple-electrode ion chamber technique that yields the absolute intensity of the X-ray beam and the photoabsorption cross section. To improve the purity of the incident X rays, the electron storage ring was operated at an energy lower than the normal mode, and thin filters were used. The W values are derived from the measured photon intensity and photoabsorption cross section, using the mean charges of the residual ions obtained in previous work. A considerable oscillation of the W values with the photon energy was found in the region near the krypton 3d electron ionization edge. The results are discussed and compared with data in the literature for low-energy electrons and with the calculations from a model that includes multiple photoionization effects related to inner-shell ionization.

  20. L-shell spectroscopic diagnostics of radiation from krypton HED plasma sources.

    Science.gov (United States)

    Petkov, E E; Safronova, A S; Kantsyrev, V L; Shlyaptseva, V V; Rawat, R S; Tan, K S; Beiersdorfer, P; Hell, N; Brown, G V

    2016-11-01

    X-ray spectroscopy is a useful tool for diagnosing plasma sources due to its non-invasive nature. One such source is the dense plasma focus (DPF). Recent interest has developed to demonstrate its potential application as a soft x-ray source. We present the first spectroscopic studies of krypton high energy density plasmas produced on a 3 kJ DPF device in Singapore. In order to diagnose spectral features, and to obtain a more comprehensive understanding of plasma parameters, a new non-local thermodynamic equilibrium L-shell kinetic model for krypton was developed. It has the capability of incorporating hot electrons, with different electron distribution functions, in order to examine the effects that they have on emission spectra. To further substantiate the validity of this model, it is also benchmarked with data gathered from experiments on the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory, where data were collected using the high resolution EBIT calorimeter spectrometer.

  1. Short wavelength laser calculations for electron pumping in neon-like krypton (Kr XXVII)

    Science.gov (United States)

    Feldman, U.; Bhatia, A. K.; Suckewer, S.

    1983-01-01

    Calculations of electron impact collision strengths and spontaneous radiative decay rates are made for neon-like krypton (Kr XXVII) for the 2s2 2p6, 2s2 2p5 3s, 2s2 2p5 3p, and 2s2 2p5 3d configurations. From these atomic data, the level populations as a function of the electron density are calculated at two temperatures, 1 x 10 to the 7th K and 3 x 10 to the 7th K. An analysis of level populations reveals that a volume of krypton in which a significant number of the ions are in the Kr XXVII degree of ionization can produce a significant gain in transition between the 2s2 2p5 3s and 2s2 2p5 3p configurations. At an electron density of 1 x 10 to the 19th/cu cm the plasma length has to be of the order of 1 m; at a density of 1 x 10 to the 21st/cu cm the length is reduced to approximately 0.5 cm; and at an electron density of 1 x 10 to the 22nd/cu cm the length of the plasma is further reduced to approximately 1 mm.

  2. Krypton yellow laser for the treatment of macular hole in high myopia without retinal detachment.

    Science.gov (United States)

    Cai, Ji-Ping; Cheng, Jin-Wei; Ma, Xiao-Ye; Li, Yu-Zhen; Li, You; Wei, Rui-Li

    2008-12-01

    To evaluate the prophylactic effect of krypton yellow laser for the treatment of macular holes in high myopic eyes in order to reduce the risk of retinal detachment. Twenty-seven eyes of 27 patients with high myopia and macular holes were randomly assigned to two groups. Fifteen patients (group A, 15 eyes) were subject to laser photocoagulation around the hole margin along with an oral placebo (vitamin B1), while 12 patients (group B, 12 eyes) were only given the oral placebo (vitamin B1). The incident rate of retinal detachment due to macular hole and the mean best-corrected visual acuity of the two groups before and after treatment were measured. The data were statistically tested by X2 test and Student's t test. The incident rates of retina1 detachment in group A and group B were 20%(3/15) and 58.3%(7/12), respectively (X2=4.201, P0.05). The mean BCVA of group B on the initial examination was 24/200, while the mean BCVA at the final follow-up was 30/200 (P>0.05). No significant difference in initial visual acuity (P>0.05) or final visual acuity (P>0.05) was found between the two groups. Krypton yellow laser photocoagulation could reduce the incidence of retinal detachment due to a macular hole in high myopia with acceptable functional results in this study.

  3. A GCMC simulation and experimental study of krypton adsorption/desorption hysteresis on a graphite surface.

    Science.gov (United States)

    Prasetyo, Luisa; Horikawa, Toshihide; Phadungbut, Poomiwat; Johnathan Tan, Shiliang; Do, D D; Nicholson, D

    2016-09-15

    Adsorption isotherms and isosteric heats of krypton on a highly graphitized carbon black, Carbopack F, have been studied with a combination of Monte Carlo simulation and high-resolution experiments at 77K and 87K. Our investigation sheds light on the microscopic origin of the experimentally observed, horizontal hysteresis loop in the first layer, and the vertical hysteresis-loop in the second layer, and is found to be in agreement with our recent Monte Carlo simulation study (Diao et al., 2015). From detailed analysis of the adsorption isotherm, the latter is attributed to the compression of an imperfect solid-like state in the first layer, to form a hexagonally packed, solid-like state, immediately following the first order condensation of the second layer. To ensure that capillary condensation in the confined spaces between microcrystallites of Carbopack F does not interfere with these hysteresis loops, we carried out simulations of krypton adsorption in the confined space of a wedge-shaped pore that mimics the interstices between particles. These simulations show that, up to the third layer, any such interference is negligible. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. An experimental study on choroidal neovascularization induced by Krypton laser in rat model.

    Science.gov (United States)

    Cui, Jing; Liu, Yuanyuan; Zhang, Jingkai; Yan, Hua

    2014-01-01

    The purpose of this work was to study the efficacy and safety of choroidal neovascularization (CNV) formation induced by Krypton laser in Brown Norway (BN) rats, and observe the trend of the change of CNV after laser photocoagulation. Twenty-five male BN rats were involved in this study. Two eyes of one rat without any laser photocoagulation were randomly selected as the control group, and the other 48 eyes of 24 rats were selected as the experimental group. Eight eyes of four rats were randomly selected to receive the examinations of fundus fluorescein angiography (FFA), histopathology, and transmission electron microscopy 3, 7, 14, 21, 28, and 56 days after laser photocoagulation. After laser photocoagulation, the leakage appeared in burns on day 7 (59%), reached the peak on day 21 (84%), (p0.05). The thickness of CNV increased from day 7 to day 21 (p0.05). The experimental model of CNV can be successfully induced by Krypton laser in rats with a stable, long-lasting, and high success rate. After laser photocoagulation, the leakages appear on day 7, reach the peak on day 21, and remain stable after day 21.

  5. Prototype tests for the liquid Krypton, Calorimeter of the CP-violation Experiment NA48

    CERN Document Server

    Viehauser, Georg

    This work 1s the result of a one year stay as a technical student in the NA48 group at the European Center for Nuclear Research CERN from May 1992 to May 1993. The NA48 experiment is a fixed target experiment at the CERN Super Proton Synchrotron (SPS) to study direct CP violation in neutral kaon decays. The aim of the experiment is the measurement of the ratio of the CP violation parameters £ '/£. Chapter 1 will explain the origin of these parameters and our current knowledge of their size. Chapter 2 will give a description of the NA48 experiment. A crucial part of the experiment will be a photon calorimeter filled with liquid krypton. It has to meet very ambitious demands concerning the high rate capability and the energy, space and time resolutions. In chapter 3 the principles of electromagnetic calorimetry and ionization chambers are reviewed. In 1992 two test beam exposures of a prototype of the liquid krypton calorimeter were performed. A description of these tests will be given in chapter 4. During th...

  6. Effective and accurate approach for modeling of commensurate–incommensurate transition in krypton monolayer on graphite

    International Nuclear Information System (INIS)

    Ustinov, E. A.

    2014-01-01

    Commensurate–incommensurate (C-IC) transition of krypton molecular layer on graphite received much attention in recent decades in theoretical and experimental researches. However, there still exists a possibility of generalization of the phenomenon from thermodynamic viewpoint on the basis of accurate molecular simulation. Recently, a new technique was developed for analysis of two-dimensional (2D) phase transitions in systems involving a crystalline phase, which is based on accounting for the effect of temperature and the chemical potential on the lattice constant of the 2D layer using the Gibbs–Duhem equation [E. A. Ustinov, J. Chem. Phys. 140, 074706 (2014)]. The technique has allowed for determination of phase diagrams of 2D argon layers on the uniform surface and in slit pores. This paper extends the developed methodology on systems accounting for the periodic modulation of the substrate potential. The main advantage of the developed approach is that it provides highly accurate evaluation of the chemical potential of crystalline layers, which allows reliable determination of temperature and other parameters of various 2D phase transitions. Applicability of the methodology is demonstrated on the krypton–graphite system. Analysis of phase diagram of the krypton molecular layer, thermodynamic functions of coexisting phases, and a method of prediction of adsorption isotherms is considered accounting for a compression of the graphite due to the krypton–carbon interaction. The temperature and heat of C-IC transition has been reliably determined for the gas–solid and solid–solid system

  7. Evaluation of target power supplies for krypton storage in sputter-deposited metals

    International Nuclear Information System (INIS)

    Greenwell, E.N.; McClanahan, E.D.; Moss, R.W.

    1986-04-01

    Implantation of 85 Kr in a growing sputtered metal deposit has been studied for the containment of 85 Kr recovered from the reprocessing of spent nuclear fuel. PNL, as part of DOE's research program for 85 Kr storage, has developed krypton trapping storage devices (KTSDs) in a range of sizes for ''cold'' and radioactive testing. The KTSD is a stainless steel canister that contains a sputtering target for depositing an amorphous rare-earth transition metal on the inner wall and simultaneously implanting low-energy krypton ions in the growing deposit. This report covers the design requirements for the target power supply and the description, testing and evaluation of three basic designs. The designs chosen for evaluation were: (1) a standard commercial power supply with an external PNL-designed current interrupter, (2) a commercially manufactured power supply with an integral series-type interrupter, and (3) a commercially manufactured power supply with an integral shunt-type interrupter. The units were compared on the basis of performance, reliability, and life-cycle cost. 8 refs., 9 figs., 2 tabs

  8. Automated Sampling and Extraction of Krypton from Small Air Samples for Kr-85 Measurement Using Atom Trap Trace Analysis

    International Nuclear Information System (INIS)

    Hebel, S.; Hands, J.; Goering, F.; Kirchner, G.; Purtschert, R.

    2015-01-01

    Atom-Trap-Trace-Analysis (ATTA) provides the capability of measuring the Krypton-85 concentration in microlitre amounts of krypton extracted from air samples of about 1 litre. This sample size is sufficiently small to allow for a range of applications, including on-site spot sampling and continuous sampling over periods of several hours. All samples can be easily handled and transported to an off-site laboratory for ATTA measurement, or stored and analyzed on demand. Bayesian sampling methodologies can be applied by blending samples for bulk measurement and performing in-depth analysis as required. Prerequisite for measurement is the extraction of a pure krypton fraction from the sample. This paper introduces an extraction unit able to isolate the krypton in small ambient air samples with high speed, high efficiency and in a fully automated manner using a combination of cryogenic distillation and gas chromatography. Air samples are collected using an automated smart sampler developed in-house to achieve a constant sampling rate over adjustable time periods ranging from 5 minutes to 3 hours per sample. The smart sampler can be deployed in the field and operate on battery for one week to take up to 60 air samples. This high flexibility of sampling and the fast, robust sample preparation are a valuable tool for research and the application of Kr-85 measurements to novel Safeguards procedures. (author)

  9. The determination of surface of powders by BET method using nitrogen and krypton with computer calculation of the results

    International Nuclear Information System (INIS)

    Dembinski, W.; Zlotowski, T.

    1973-01-01

    A computer program written in FORTRAN language for calculations of final results of specific surface analysis based on BET theory has been described. Two gases - nitrogen and krypton were used. A technical description of measuring apparaturs is presented as well as theoretical basis of the calculations together with statistical analysis of the results for uranium compounds powders. (author)

  10. Methane from wood

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, T. F.; Barreto, L.; Kypreos, S.; Stucki, S

    2005-07-15

    The role of wood-based energy technologies in the Swiss energy system in the long-term is examined using the energy-system Swiss MARKAL model. The Swiss MARKAL model is a 'bottom-up' energy-systems optimization model that allows a detailed representation of energy technologies. The model has been developed as a joint effort between the Energy Economics Group (EEG) at Paul Scherrer Institute PSI) and the University of Geneva and is currently used at PSI-EEG. Using the Swiss MARKAL model, this study examines the conditions under which wood-based energy technologies could play a role in the Swiss energy system, the most attractive pathways for their use and the policy measures that could support them. Given the involvement of PSI in the ECOGAS project, especial emphasis is put on the production of bio-SNG from wood via gasification and methanation of syngas and on hydrothermal gasification of woody biomass. Of specific interest as weIl is the fraction of fuel used in passenger cars that could be produced by locally harvested wood. The report is organized as follows: Section 2 presents a brief description of the MARKAL model. Section 3 describes the results of the base case scenario, which represents a plausible, 'middle-of-the-road' development of the Swiss energy system. Section 4 discusses results illustrating the conditions under which the wood-based methanation technology could become competitive in the Swiss energy market, the role of oil and gas prices, subsidies to methanation technologies and the introduction of a competing technology, namely the wood-based Fischer-Tropsch synthesis. FinaIly, section 5 outlines some conclusions from this analysis. (author)

  11. Methane from wood

    International Nuclear Information System (INIS)

    Schulz, T. F.; Barreto, L.; Kypreos, S.; Stucki, S.

    2005-07-01

    The role of wood-based energy technologies in the Swiss energy system in the long-term is examined using the energy-system Swiss MARKAL model. The Swiss MARKAL model is a 'bottom-up' energy-systems optimization model that allows a detailed representation of energy technologies. The model has been developed as a joint effort between the Energy Economics Group (EEG) at Paul Scherrer Institute PSI) and the University of Geneva and is currently used at PSI-EEG. Using the Swiss MARKAL model, this study examines the conditions under which wood-based energy technologies could play a role in the Swiss energy system, the most attractive pathways for their use and the policy measures that could support them. Given the involvement of PSI in the ECOGAS project, especial emphasis is put on the production of bio-SNG from wood via gasification and methanation of syngas and on hydrothermal gasification of woody biomass. Of specific interest as weIl is the fraction of fuel used in passenger cars that could be produced by locally harvested wood. The report is organized as follows: Section 2 presents a brief description of the MARKAL model. Section 3 describes the results of the base case scenario, which represents a plausible, 'middle-of-the-road' development of the Swiss energy system. Section 4 discusses results illustrating the conditions under which the wood-based methanation technology could become competitive in the Swiss energy market, the role of oil and gas prices, subsidies to methanation technologies and the introduction of a competing technology, namely the wood-based Fischer-Tropsch synthesis. FinaIly, section 5 outlines some conclusions from this analysis. (author)

  12. Methanogenesis and methane genes

    International Nuclear Information System (INIS)

    Reeve, J.N.; Shref, B.A.

    1991-01-01

    An overview of the pathways leading to methane biosynthesis is presented. The steps investigated to date by gene cloning and DNA sequencing procedures are identified and discussed. The primary structures of component C of methyl coenzyme M reductase encoded by mcr operons in different methanogens are compared. Experiments to detect the primary structure of the genes encoding F420 reducing hydrogenase (frhABG) and methyl hydrogen reducing hydrogenase (mvhDGA) in methanobacterium thermoautotrophicum strain H are compared with each other and with eubacterial hydrogenase encoding genes. A biotechnological use for hydrogenases from hypermorphillic archaebacteria is suggested. (author)

  13. In situ measurements of krypton in xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed

    International Nuclear Information System (INIS)

    Brown, E; Rosendahl, S; Huhmann, C; Weinheimer, C; Kettling, H

    2013-01-01

    A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of 330±200 ppt.

  14. Reaction of methane with coal

    Energy Technology Data Exchange (ETDEWEB)

    Yang, K.; Batts, B.D.; Wilson, M.A.; Gorbaty, M.L.; Maa, P.S.; Long, M.A.; He, S.J.X.; Attala, M.I. [Macquarie University, Macquarie, NSW (Australia). School of Chemistry

    1997-10-01

    A study of the reactivities of Australian coals and one American coal with methane or methane-hydrogen mixtures, in the range 350-400{degree}C and a range of pressures (6.0-8.3 MPa, cold) is reported. The effects of aluminophosphates (AIPO) or zeolite catalysts, with and without exchanged metals, on reactivity have also been examined. Yields of dichloromethane extractable material are increased by using a methane rather than a nitrogen atmosphere and different catalysts assist dissolution to various extends. It appears that surface exchanged catalysts are effective, but incorporating metals during AIPO lattice formation is detrimental. Aluminium phosphate catalysts are unstable to water produced during coal conversion, but are still able to increase extraction yields. For the American coal, under methane-hydrogen and a copper exchanged zeolite, 51.5% conversion was obtained, with a product selectivity close to that obtained under hydrogen alone, and with only 2% hydrogen consumption. The conversion under methane-hydrogen was also to that obtained under hydrogen alone, while a linear dependence of conversion on proportion of methane would predict a 43% conversion under methane-hydrogen. This illustrates a synergistic effect of the methane-hydrogen atmosphere for coal liquefaction using this catalyst systems. 31 refs., 5 figs., 7 tabs.

  15. Methane adsorption on activated carbon

    NARCIS (Netherlands)

    Perl, Andras; Koopman, Folkert; Jansen, Peter; de Rooij, Marietta; van Gemert, Wim

    2014-01-01

    Methane storage in adsorbed form is a promising way to effectively and safely store fuel for vehicular transportation or for any other potential application. In a solid adsorbent, nanometer wide pores can trap methane by van der Waals forces as high density fluid at low pressure and room

  16. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    DEFF Research Database (Denmark)

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram

    2012-01-01

    oxidation of methane, the catalyst reduced from the end to the beginning of the catalyst bed and oxidized again toward the end as soon as the entire catalyst bed was reduced. On an entirely oxidized catalyst bed, only total oxidation of methane was observed and consumed the oxygen until the conditions...... of the Pd particles at increasing age of the catalyst was observed, which leads to a lower oscillation frequency. Effects of particle size, oven temperature, and oxygen/methane ratio on the oscillation behavior were studied in detail. The deactivation period (reoxidation of Pd) was much less influenced...... by the oven temperature than the ignition behavior of the catalytic partial oxidation of methane. This indicates that deactivation is caused by an autoreduction of the palladium at the beginning of the catalyst bed due to the high temperature achieved by total oxidation of methane....

  17. Numerical study of effect of oxygen fraction on local entropy ...

    Indian Academy of Sciences (India)

    This study considers numerical simulation of the combustion of methane with air, including oxygen and nitrogen, in a burner and the numerical solution of local entropy generation rate due to high temperature and velocity gradients in the combustion chamber. The effects of equivalence ratio () and oxygen percentage () ...

  18. Cleansing, methanation is democratizing; Depollution, la methanisation se democratise

    Energy Technology Data Exchange (ETDEWEB)

    Aumond, N.

    2005-06-01

    The French company Naskeo is developing a biological treatment method for small industrial pollutant sources. With a treatment capacity of 36 kg COD (chemical oxygen demand) per m{sup 3} and per day, this process is two times more efficient than todays commercialized anaerobic stations. The method involves the classical methanation process and uses the Provae technology developed by the national institute of agronomical research (Inra), which combines the fixed bed and fluidized bed technologies. Short paper. (J.S.)

  19. Oxygen Therapy

    Science.gov (United States)

    ... their breathing to dangerously low levels. Will I need oxygen when I sleep? Usually if you use supplemental oxygen during the ... your health care provider tells you you only need to use oxygen for exercise or sleep. Even if you feel “fine” off of your ...

  20. Methane production and methane consumption: a review of processes underlying wetland methane fluxes.

    NARCIS (Netherlands)

    Segers, R.

    1998-01-01

    Potential rates of both methane production and methane consumption vary over three orders of magnitude and their distribution is skew. These rates are weakly correlated with ecosystem type, incubation temperature, in situ aeration, latitude, depth and distance to oxic/anoxic interface. Anaerobic

  1. Simplifiying global biogeochemistry models to evaluate methane emissions

    Science.gov (United States)

    Gerber, S.; Alonso-Contes, C.

    2017-12-01

    Process-based models are important tools to quantify wetland methane emissions, particularly also under climate change scenarios, evaluating these models is often cumbersome as they are embedded in larger land-surface models where fluctuating water table and the carbon cycle (including new readily decomposable plant material) are predicted variables. Here, we build on these large scale models but instead of modeling water table and plant productivity we provide values as boundary conditions. In contrast, aerobic and anaerobic decomposition, as well as soil column transport of oxygen and methane are predicted by the model. Because of these simplifications, the model has the potential to be more readily adaptable to the analysis of field-scale data. Here we determine the sensitivity of the model to specific setups, parameter choices, and to boundary conditions in order to determine set-up needs and inform what critical auxiliary variables need to be measured in order to better predict field-scale methane emissions from wetland soils. To that end we performed a global sensitivity analysis that also considers non-linear interactions between processes. The global sensitivity analysis revealed, not surprisingly, that water table dynamics (both mean level and amplitude of fluctuations), and the rate of the carbon cycle (i.e. net primary productivity) are critical determinants of methane emissions. The depth-scale where most of the potential decomposition occurs also affects methane emissions. Different transport mechanisms are compensating each other to some degree: If plant conduits are constrained, methane emissions by diffusive flux and ebullition compensate to some degree, however annual emissions are higher when plants help to bypass methanotrophs in temporally unsaturated upper layers. Finally, while oxygen consumption by plant roots help creating anoxic conditions it has little effect on overall methane emission. Our initial sensitivity analysis helps guiding

  2. Oxidative coupling of methane using inorganic membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.H.; Moser, W.R.; Dixon, A.G. [Worcester Polytechnic Institute, MA (United States)] [and others

    1995-12-31

    The goal of this research is to improve the oxidative coupling of methane in a catalytic inorganic membrane reactor. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and relatively higher yields than in fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for formation of CO{sub x} products. Such gas phase reactions are a cause for decreased selectivity in oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Modeling work which aimed at predicting the observed experimental trends in porous membrane reactors was also undertaken in this research program.

  3. Methane Recycling During Burial of Methane Hydrate-Bearing Sediments

    Science.gov (United States)

    You, K.; Flemings, P. B.

    2017-12-01

    We quantitatively investigate the integral processes of methane hydrate formation from local microbial methane generation, burial of methane hydrate with sedimentation, and methane recycling at the base of the hydrate stability zone (BHSZ) with a multiphase multicomponent numerical model. Methane recycling happens in cycles, and there is not a steady state. Each cycle starts with free gas accumulation from hydrate dissociation below the BHSZ. This free gas flows upward under buoyancy, elevates the hydrate saturation and capillary entry pressure at the BHSZ, and this prevents more free gas flowing in. Later as this layer with elevated hydrate saturation is buried and dissociated, the large amount of free gas newly released and accumulated below rapidly intrudes into the hydrate stability zone, drives rapid hydrate formation and creates three-phase (gas, liquid and hydrate) equilibrium above the BHSZ. The gas front retreats to below the BHSZ until all the free gas is depleted. The shallowest depth that the free gas reaches in one cycle moves toward seafloor as more and more methane is accumulated to the BHSZ with time. More methane is stored above the BHSZ in the form of concentrated hydrate in sediments with relatively uniform pore throat, and/or with greater compressibility. It is more difficult to initiate methane recycling in passive continental margins where the sedimentation rate is low, and in sediments with low organic matter content and/or methanogenesis reaction rate. The presence of a permeable layer can store methane for significant periods of time without recycling. In a 2D system where the seafloor dips rapidly, the updip gas flow along the BHSZ transports more methane toward topographic highs where methane gas and elevated hydrate saturation intrude deeper into the hydrate stability zone within one cycle. This could lead to intermittent gas venting at seafloor at the topographic highs. This study provides insights on many phenomenon associated with

  4. High-temperature conversion of methane on a composite gadolinia-doped ceria-gold electrode

    DEFF Research Database (Denmark)

    Marina, O.A.; Mogensen, Mogens Bjerg

    1999-01-01

    Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials such as n......Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials...... such as nickel and platinum. CG4 was found to exhibit a low electrocatalytic activity for methane oxidation as well as no significant reforming activity implying that the addition of an electrocatalyst or cracking catalyst to the CG4 anode is required for SOFC operating on methane. The methane conversion...... observed at the open-circuit potential and low anodic overpotentials seems to be due to thermal methane cracking in the gas phase and on the alumina surfaces in the cell housing. At high anodic overpotentials, at electrode potentials where oxygen evolution was expected to take place, the formation of CO(2...

  5. Methane Hydrates: Chapter 8

    Science.gov (United States)

    Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

    2008-01-01

    Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

  6. Titan's methane clock

    Science.gov (United States)

    Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

    2010-04-01

    Measurements of the 12C/13C and D/H isotopic ratios in Titan's methane show intriguing differences from the values recorded in the giant planets. This implies that either (1) the atmosphere was differently endowed with material at the time of formation, or (2) evolutionary processes are at work in the moon's atmosphere - or some combination of the two. The Huygens Gas Chromatograph Mass Spectrometer Instrument (GCMS) found 12CH4/13CH4 = 82 +/- 1 (Niemann et al. 2005), some 7% lower than the giant planets' value of 88 +/- 7 (Sada et al. 1996), which closely matches the terrestrial inorganic standard of 89. The Cassini Composite Infrared Spectrometer (CIRS) has previously reported 12CH4/13CH4 of 77 +/-3 based on nadir sounding, which we now revise upwards to 80 +/- 4 based on more accurate limb sounding. The CIRS and GCMS results are therefore in agreement about an overall enrichment in 13CH4 of ~10%. The value of D/H in Titan's CH4 has long been controversial: historical measurements have ranged from about 8-15 x 10-5 (e.g. Coustenis et al. 1989, Coustenis et al. 2003). A recent measurement based on CIRS limb data by Bezard et al. (2007) puts the D/H in CH4 at (13 +/- 1) x 10-5, very much greater than in Jupiter and Saturn, ~2 x 10-5 (Mahaffy et al. 1998, Fletcher et al. 2009). To add complexity, the 12C/13C and D/H vary among molecules in Titan atmosphere, typically showing enhancement in D but depletion in 13C in the daughter species (H2, C2H2, C2H6), relative to the photochemical progenitor, methane. Jennings et al. (2009) have sought to interpret the variance in carbon isotopes as a Kinetic Isotope Effect (KIE), whilst an explanation for the D/H in all molecules remains elusive (Cordier et al. 2008). In this presentation we argue that evolution of isotopic ratios in Titan's methane over time forms a ticking 'clock', somewhat analogous to isotopic ratios in geochronology. Under plausible assumptions about the initial values and subsequent replenishment, various

  7. Irradiation temperature memorization by retention of krypton-85. Application to the temperature determination for the internal cladding surface of fuel elements in PWR

    International Nuclear Information System (INIS)

    Fremiot, Claude

    1977-01-01

    The temperature of the inner surface of the cladding fuel elements, which can not be measured directly, can be determined after irradiation. During its stage within the reactor, the cladding is bombarded by krypton-85 fission product, which is trapped in the metallic lattice defects. The experience shows that the krypton release during postirradiation heating takes place at the irradiation temperature. This method was applied for PWR fuel element. A very simple model for retention and release of the krypton is proposed. The krypton trap-energy in zircaloy partakes in this model. This technique can be ordered amongst the Hot'Lab' control methods and expert appraisements. It is pointed out that the principal interest in that method is the fact that it does not need any fuel element instrumentation. At the present, this method is being used by CEA for routine-control. [fr

  8. Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

    Energy Technology Data Exchange (ETDEWEB)

    Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)

    2013-12-15

    Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

  9. 99Tcm-Technegas and krypton-81 m ventilation scintigraphy: a comparison in known respiratory disease

    International Nuclear Information System (INIS)

    James, J.M.; Lloyd, J.J.; Leahy, B.C.; Church, S.; Hardy, C.C.; Shields, R.A.; Prescott, M.C.; Testa, H.J.

    1992-01-01

    The new radiopharmaceutical 99 Tc m -Technegas, a suspension of ultrafine technetium-99m labelled carbon particles, produces high-quality images of ventilation and has the advantage of continuous availability. Technegas was compared with krypton-81m gas in 40 patients with a variety of established respiratory diseases. Disparities were seen in five patients in five diagnostic groups and may be a consequence of differing physical properties of the two agents and the different inhalation techniques used. In addition, on the Technegas images, (1) Hot spots were seen in 50% of patients, particularly in those with a degree of airways obstruction; (2) preferential basal deposition of activity was seen in 30%, particularly in patients with idiopathic pulmonary fibrosis. Both features were significantly associated with parameters of pulmonary function indicating obstructive lung disease in the former case and restrictive lung disease in the latter. (author)

  10. Deactivation of tracer-flo equipment thru retrieval of its radioactive Krypton-85 gas

    International Nuclear Information System (INIS)

    Domondon, D.B.; Rara, R.B.; Borras, A.M.

    1994-01-01

    Tracer-flo equipment must be cleared of Krypton-85 before these can be transported. The rules and regulations on safe transport of radioactive materials require Kr-85 gas to be transported in an approved container. A new innovative technique/procedure in deactivating tracer-flo equipment i.e., without separation of the Kr-85 from the nitrogen was developed by the authors. The developed procedure was successfully applied in four tracer-flo equipment of three (3) semiconductor firms. In the process, the three firms have saved about US$ 28,000.00 (P 800,000.00) if the deactivation were undertaken by a foreign service company. The Philippine Nuclear Research Institute (PNRI) retrieved about P 382,000.00 worth of Kr-85 that could be used in industrial applications such as leak tracing of buried pipes, etc. (author). 1 ref.; 5 figs

  11. Generalized oscillator strengths for 5s, 5s', and 5p excitations of krypton

    International Nuclear Information System (INIS)

    Li Wenbin; Zhu Linfan; Yuan Zhensheng; Sun Jianmin; Cheng Huadong; Xu Kezun; Zhong Zhiping; Liu Xiaojing

    2003-01-01

    The absolute generalized oscillator strengths (GOSs) for 5s, 5s ' , 5p [5/2] 3,2 , 5p [3/2] 1,2 , and 5p [1/2] 0 transitions of krypton have been determined in a large K 2 region at a high electron-impact energy of 2500 eV. The positions of the minima and maxima of these GOSs have been determined. The present results show that the angular resolution and pressure effect have great influence on the position and the amplitude of the minimum for the GOS of 5s+5s ' transitions. When these effects are considered, the measured minimum position for the GOS of 5s+5s ' transitions is in excellent agreement with the calculation of Chen and Msezane [J. Phys. B 33, 5397 (2000)

  12. Review of the adsorption of radioactive krypton and xenon on activated charcoal

    International Nuclear Information System (INIS)

    Underhill, D.W.; Moeller, D.W.

    1981-01-01

    This report summarizes the results of a critical review of the published literature on the adsorption of radioactive krypton and xenon on activated charcoal. This review, which was supported by the Advisory Committee on Reactor Safeguards, US Nuclear Regulatory Commission, showed that (a) individual charcoals have a wide range of adsoprtion coefficients and therefore the performance of a given bed is heavily dependent on the quality of the charcoal it contains; (b) because of the detrimental effects of mass transfer on noble gas adsorption, consideration should be given to including this factor in developing technical specifications for adsorption beds; and (c) additional research is needed on the determination of the inter-relationship of moisture and temperature and their effects on adsorption bed performance

  13. Pilot plant development for adsorptive krypton separation from dissolver off-gas

    International Nuclear Information System (INIS)

    Ringel, H.; Printz, R.

    1987-01-01

    In view of hot cell application a separation process was investigated for the retention of Kr-85 from gaseous effluents. In the flow sheet only adsorption beds are applied. The most efficient process scheme is adsorption of the noble gas on activated charcoal and thereafter separation of the coadsorbed gas species like N 2 , O 2 , Xe and CO 2 from the krypton by gas chromatography. Adsorption is at normal pressure and low temperatures of up to -160 0 C, whereas desorption is at elevated temperatures and under helium purge. Influences on the process operation like off-gas composition, adsorption temperatures and adsorbent are experimentally investigated, as well as the behavior of trace impurities in the adsorption columns. On the basis of pilot plant operation the main components for a full scale facility are being designed

  14. The Upgrade of the Control System for the CERN/NA62 Liquid Krypton Detector

    CERN Document Server

    Moraux, A; Bremer, J; Falaleev, V; Gonidec, A; Passardi, Giorgio; Pezzetti, M

    2009-01-01

    The NA62 experiment is a continuation of the CERN kaon research program and particularly of the NA48 experiment which was designed in the early 90’s to measure the direct CP violation with a very high precision. An important component of the experimental setup is an electromagnetic calorimeter filled with 9000 liters of high-purity liquid krypton at 120 K. Its associated cryogenic system aims at providing a very high reliability and stable thermal conditions with temperature stabilization better than 0.1 K. The upgrade of the cryogenic control system was motivated by the need of ensuring its durability and standardization for the long term fixed-target physics program at the CERN Super Proton Synchrotron (SPS). This paper describes the adopted technical solutions to minimize the control shutdown and emphasizes the related safety issues.

  15. Femtosecond two-photon laser-induced fluorescence of krypton for high-speed flow imaging.

    Science.gov (United States)

    Wang, Yejun; Capps, Cade; Kulatilaka, Waruna D

    2017-02-15

    Ultrashort-pulse (femtosecond-duration) two-photon laser-induced fluorescence (fs-TPLIF) of an inert gas tracer krypton (Kr) is investigated. A detailed spectroscopic study of fluorescence channels followed by the 5p'←←4p excitation of Kr at 204.1 nm is reported. The experimental line positions in the 750-840 nm emission region agree well with the NIST Atomic Spectra Database. The present work provides an accurate listing of relative line strengths in this spectral region. In the range of laser pulse energies investigated, a quadratic dependence was observed between the Kr-TPLIF signal and the laser pulse energy. The single-laser-shot 2D TPLIF images recorded in an unsteady jet demonstrate the potential of using fs excitation at 204.1 nm for mixing and flow diagnostic studies using Kr as an inert gas tracer.

  16. Monitoring and assay procedures for krypton-85 used in circulatory tests

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Jr., J. M.; Williams, K. D.

    1963-11-15

    During the past five years, krypton-85 has been used extensively at the National Institutes of health and by the heart Catheterization laboratory in the identification of circulatory shunts. Several methods of assaying the incoming shipments of radioactive gas are given. These consist of ionization chamber measurements, gamma ray spectrometry, and gross photon counting of the cylinder surface with an end-window Geiger-Mueller tube. A device (consisting of a log-count-rate meter, recorder, and G.M. tube) is used to continuously monitor the laboratory. The method of calibrating this device is presented. A means for removing contaminated air from the vicinity of the operating table was devised. The results of air clearance studies of the room are included. (auth)

  17. Cyclotron production of krypton-77 for regional cerebral blood flow measurement

    International Nuclear Information System (INIS)

    Houdayer, A.J.; Meyer, E.; Yamamoto, Y.L.

    1977-01-01

    Krypton-77 has favourable decay characteristics for use in studies of regional cerebral blood flow, and the gas may be administered by inhalation. A description is given of the preparation and separation of radioactive sources of 77 Kr gas of strength between 1 and 5 mCi. The sources were produced via the reaction 79 Br(p,3n) 77 Kr induced by 30 MeV protons in targets of NaBr powder enriched to 99.75% 79 Br. A simple and rapid separation of the other contaminants produced in the target was achieved by means of cold traps. The fresh product showed no gamma ray spectra other than those of 77 Kr and 79 Kr, and only traces of 79 Kr were present. (U.K.)

  18. Separation of krypton from dissolver off-gas of a reprocessing plant using preparative gas chromatography

    International Nuclear Information System (INIS)

    Matoni, M.

    1984-02-01

    Kr-85 can be separated from the pre-purified purge air in the final processing step of the purification phase for dissolver off-gases of a reprocessing plant with the aid of preparative gas chromatography. Activated carbon adsorbers in combination with helium as carrier gas permits maximum gas mixture through-flow. A separation temperature of 30 0 C is considered optimal. An adsorbent volume of 40 dm 3 is necessary for processing the residual gas flow of 2.5 Nm 3 /h; the adsorbent is divided between 2 columns linked in series each of which are 2 m long with an internal diameter of 100 mm. The helium flow required is five times greater than the off-gas flow. The degree of purity for krypton is greater than 90% for a decontamination factor of greater than 1000. (orig./HP) [de

  19. High resolution krypton M/sub 4,5/ x-ray emission spectra

    International Nuclear Information System (INIS)

    Perera, R.C.C.; Hettrick, M.C.; Lindle, D.W.

    1987-10-01

    High resolution M/sub 4,5/ (3d → 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme ultraviolet and soft x-ray wave lengths. The nominal resolving power of the instrument, E/ΔE, is about 300 in this energy range (∼80 eV). Three dipole-allowed 3d → 4p emission lines were observed at 80.98 eV, 80.35 eV and 79.73 eV. A broad peak at about 82.3 eV is tentatively assigned to transitions resulting from Kr 2+ , and effects of excitation energy on M/sub 4,5/ x-ray emission were observed. 9 refs., 3 figs., 1 tab

  20. Oxygen Therapy

    Directory of Open Access Journals (Sweden)

    Bonnie Solmes

    2000-01-01

    Full Text Available LTOT is prescribed for people with chronic lung disease in whom there is a decrease in the ability of the lungs to supply enough oxygen to the body. The heart is obliged to pump faster to meet the body's oxygen requirements. This may place undue stress on the heart, resulting in palpitations, dizziness and fatigue. A low oxygen level in arterial blood is also harmful to the heart, the brain and the pulmonary blood vessels. Oxygen therapy is used to break this cycle. A person with low blood oxygen will often be able to accomplish more with less fatigue with the help of supplemental oxygen therapy. Shortness of breath is a mechanical problem resulting from the effects of chronic obstructive pulmonary disease. Oxygen therapy may or may not reduce shortness of breath, but it will help the lungs and heart to function with less stress.